WorldWideScience

Sample records for aqueous mineral carbonation

  1. Cost evaluation of CO2 sequestration by aqueous mineral carbonation

    International Nuclear Information System (INIS)

    A cost evaluation of CO2 sequestration by aqueous mineral carbonation has been made using either wollastonite (CaSiO3) or steel slag as feedstock. First, the process was simulated to determine the properties of the streams as well as the power and heat consumption of the process equipment. Second, a basic design was made for the major process equipment, and total investment costs were estimated with the help of the publicly available literature and a factorial cost estimation method. Finally, the sequestration costs were determined on the basis of the depreciation of investments and variable and fixed operating costs. Estimated costs are 102 and 77 euro/ton CO2 net avoided for wollastonite and steel slag, respectively. For wollastonite, the major costs are associated with the feedstock and the electricity consumption for grinding and compression (54 and 26 euro/ton CO2 avoided, respectively). A sensitivity analysis showed that additional influential parameters in the sequestration costs include the liquid-to-solid ratio in the carbonation reactor and the possible value of the carbonated product. The sequestration costs for steel slag are significantly lower due to the absence of costs for the feedstock. Although various options for potential cost reduction have been identified, CO2 sequestration by current aqueous carbonation processes seems expensive relative to other CO2 storage technologies. The permanent and inherently safe sequestration of CO2 by mineral carbonation may justify higher costs, but further cost reductions are required, particularly in view of (current) prices of CO2 emission rights. Niche applications of mineral carbonation with a solid residue such as steel slag as feedstock and/or a useful carbonated product hold the best prospects for an economically feasible CO2 sequestration process

  2. Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing organic additives.

    OpenAIRE

    Bonfils, Benjamin; Julcour-Lebigue, Carine; Guyot, François; Bodénan, Françoise; Chiquet, Pierre; Bourgeois, Florent

    2012-01-01

    Direct aqueous mineral carbonation using organic anions has been presented by many as a promising strategy for mineral carbonation, on the basis that additives such as oxalate increase the rate and extent of dissolution of magnesium silicates several folds. Through geochemical modelling and detailed solid characterization, this paper discusses and extends our current understanding of this process. The role of disodium oxalate as a dissolution enhancing agent for olivine is thoroughly examined...

  3. Energy consumption and net CO2 sequestration of aqueous mineral carbonation

    International Nuclear Information System (INIS)

    Aqueous mineral carbonation is a potentially attractive sequestration technology to reduce CO2 emissions. The energy consumption of this technology, however, reduces the net amount of CO2 sequestered. Therefore, the energetic CO2 sequestration efficiency of aqueous mineral carbonation was studied in dependence of various process variables using either wollastonite (CaSiO3) or steel slag as feedstock. For wollastonite, the maximum energetic CO2 sequestration efficiency within the ranges of process conditions studied was 75% at 200C, 20 bar CO2, and a particle size of <38μm. The main energy-consuming process steps were the grinding of the feedstock and the compression of the CO2 feed. At these process conditions, a significantly lower efficiency was determined for steel slag (69%), mainly because of the lower Ca content of the feedstock. The CO2 sequestration efficiency might be improved substantially for both types of feedstock by, e.g., reducing the amount of process water applied and further grinding of the feedstock. The calculated energetic efficiencies warrant a further assessment of the (energetic) feasibility of CO2 sequestration by aqueous mineral carbonation on the basis of a pilot-scale process

  4. Mineral sequestration of CO2 by aqueous carbonation of coal combustion fly-ash

    International Nuclear Information System (INIS)

    The increasing CO2 concentration in the Earth's atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. A technology that could possibly contribute to reducing carbon dioxide emissions is the in-situ mineral sequestration (long term geological storage) or the ex-situ mineral sequestration (controlled industrial reactors) of CO2. In the present study, we propose to use coal combustion fly-ash, an industrial waste that contains about 4.1 wt.% of lime (CaO), to sequester carbon dioxide by aqueous carbonation. The carbonation reaction was carried out in two successive chemical reactions, first, the irreversible hydration of lime. CaO + H2O → Ca(OH)2 second, the spontaneous carbonation of calcium hydroxide suspension. Ca(OH)2 + CO2 → CaCO3 + H2O A significant CaO-CaCO3 chemical transformation (approximately 82% of carbonation efficiency) was estimated by pressure-mass balance after 2 h of reaction at 30 deg. C. In addition, the qualitative comparison of X-ray diffraction spectra for reactants and products revealed a complete CaO-CaCO3 conversion. The carbonation efficiency of CaO was independent on the initial pressure of CO2 (10, 20, 30 and 40 bar) and it was not significantly affected by reaction temperature (room temperature '20-25', 30 and 60 deg. C) and by fly-ash dose (50, 100, 150 g). The kinetic data demonstrated that the initial rate of CO2 transfer was enhanced by carbonation process for our experiments. The precipitate calcium carbonate was characterized by isolated micrometric particles and micrometric agglomerates of calcite (SEM observations). Finally, the geochemical modelling using PHREEQC software indicated that the final solutions (i.e. after reaction) are supersaturated with respect to calcium carbonate (0.7 ≤ saturation index ≤ 1.1). This experimental study demonstrates that 1 ton of fly-ash could sequester up to 26 kg of CO2, i.e. 38.18 ton of fly-ash per ton of CO2 sequestered. This confirms the

  5. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Brent Constantz; Randy Seeker; Martin Devenney

    2010-06-30

    Calera's innovative Mineralization via Aqueous Precipitation (MAP) technology for the capture and conversion of CO{sub 2} to useful materials for use in the built environment was further developed and proven in the Phase 1 Department of Energy Grant. The process was scaled to 300 gallon batch reactors and subsequently to Pilot Plant scale for the continuous production of product with the production of reactive calcium carbonate material that was evaluated as a supplementary cementitious material (SCM). The Calera SCM{trademark} was evaluated as a 20% replacement for ordinary portland cement and demonstrated to meet the industry specification ASTM 1157 which is a standard performance specification for hydraulic cement. The performance of the 20% replacement material was comparable to the 100% ordinary portland cement control in terms of compressive strength and workability as measured by a variety of ASTM standard tests. In addition to the performance metrics, detailed characterization of the Calera SCM was performed using advanced analytical techniques to better understand the material interaction with the phases of ordinary portland cement. X-ray synchrotron diffraction studies at the Advanced Photon Source in Argonne National Lab confirmed the presence of an amorphous phase(s) in addition to the crystalline calcium carbonate phases in the reactive carbonate material. The presence of carboaluminate phases as a result of the interaction of the reactive carbonate materials with ordinary portland cement was also confirmed. A Life Cycle Assessment was completed for several cases based on different Calera process configurations and compared against the life cycle of ordinary portland cement. In addition to the materials development efforts, the Calera technology for the production of product using an innovative building materials demonstration plant was developed beyond conceptual engineering to a detailed design with a construction schedule and cost estimate.

  6. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Devenney, Martin; Gilliam, Ryan; Seeker, Randy

    2014-06-01

    The objective of this project is to demonstrate an innovative process to mineralize CO2 from flue gas directly to reactive carbonates and maximize the value and versatility of its beneficial use products. The program scope includes the design, construction, and testing of a CO2 Conversion to Material Products (CCMP) Pilot Demonstration Plant utilizing CO2 from the flue gas of a power production facility in Moss Landing, CA as well as flue gas from coal combustion. This topical report covers Phase 2b, which is the construction phase of pilot demonstration subsystems that make up the integrated plant. The subsystems included are the mineralization subsystem, the Alkalinity Based on Low Energy (ABLE) subsystem, the waste calcium oxide processing subsystem, and the fiber cement board production subsystem. The fully integrated plant is now capable of capturing CO2 from various sources (gas and coal) and mineralizing into a reactive calcium carbonate binder and subsequently producing commercial size (4ftx8ft) fiber cement boards. The topical report provides a description of the “as built” design of these subsystems and the results of the commissioning activities that have taken place to confirm operability. At the end of Phase 2b, the CCMP pilot demonstration is fully ready for testing.

  7. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Devenney, Martin; Gilliam, Ryan; Seeker, Randy

    2013-08-01

    The objective of this project is to demonstrate an innovative process to mineralize CO2 from flue gas directly to reactive carbonates and maximize the value and versatility of its beneficial use products. The program scope includes the design, construction, and testing of a CO2 Conversion to Material Products (CCMP) Pilot Demonstration Plant utilizing CO2 from the flue gas of a power production facility in Moss Landing, CA. This topical report covers Subphase 2a which is the design phase of pilot demonstration subsystems. Materials of construction have been selected and proven in both lab scale and prototype testing to be acceptable for the reagent conditions of interest. The target application for the reactive carbonate material has been selected based upon small-scale feasibility studies and the design of a continuous fiber board production line has been completed. The electrochemical cell architecture and components have been selected based upon both lab scale and prototype testing. The appropriate quality control and diagnostic techniques have been developed and tested along with the required instrumentation and controls. Finally the demonstrate site infrastructure, NEPA categorical exclusion, and permitting is all ready for the construction and installation of the new units and upgrades.

  8. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas. Phase I. Final Topical Report

    International Nuclear Information System (INIS)

    Calera's innovative Mineralization via Aqueous Precipitation (MAP) technology for the capture and conversion of CO2 to useful materials for use in the built environment was further developed and proven in the Phase 1 Department of Energy Grant. The process was scaled to 300 gallon batch reactors and subsequently to Pilot Plant scale for the continuous production of product with the production of reactive calcium carbonate material that was evaluated as a supplementary cementitious material (SCM). The Calera SCM(trademark) was evaluated as a 20% replacement for ordinary portland cement and demonstrated to meet the industry specification ASTM 1157 which is a standard performance specification for hydraulic cement. The performance of the 20% replacement material was comparable to the 100% ordinary portland cement control in terms of compressive strength and workability as measured by a variety of ASTM standard tests. In addition to the performance metrics, detailed characterization of the Calera SCM was performed using advanced analytical techniques to better understand the material interaction with the phases of ordinary portland cement. X-ray synchrotron diffraction studies at the Advanced Photon Source in Argonne National Lab confirmed the presence of an amorphous phase(s) in addition to the crystalline calcium carbonate phases in the reactive carbonate material. The presence of carboaluminate phases as a result of the interaction of the reactive carbonate materials with ordinary portland cement was also confirmed. A Life Cycle Assessment was completed for several cases based on different Calera process configurations and compared against the life cycle of ordinary portland cement. In addition to the materials development efforts, the Calera technology for the production of product using an innovative building materials demonstration plant was developed beyond conceptual engineering to a detailed design with a construction schedule and cost estimate.

  9. Accelerating Mineral Carbonation Using Carbonic Anhydrase.

    Science.gov (United States)

    Power, Ian M; Harrison, Anna L; Dipple, Gregory M

    2016-03-01

    Carbonic anhydrase (CA) enzymes have gained considerable attention for their potential use in carbon dioxide (CO2) capture technologies because they are able to catalyze rapidly the interconversion of aqueous CO2 and bicarbonate. However, there are challenges for widespread implementation including the need to develop mineralization process routes for permanent carbon storage. Mineral carbonation of highly reactive feedstocks may be limited by the supply rate of CO2. This rate limitation can be directly addressed by incorporating enzyme-catalyzed CO2 hydration. This study examined the effects of bovine carbonic anhydrase (BCA) and CO2-rich gas streams on the carbonation rate of brucite [Mg(OH)2], a highly reactive mineral. Alkaline brucite slurries were amended with BCA and supplied with 10% CO2 gas while aqueous chemistry and solids were monitored throughout the experiments (hours to days). In comparison to controls, brucite carbonation using BCA was accelerated by up to 240%. Nesquehonite [MgCO3·3H2O] precipitation limited the accumulation of hydrated CO2 species, apparently preventing BCA from catalyzing the dehydration reaction. Geochemical models reproduce observed reaction progress in all experiments, revealing a linear correlation between CO2 uptake and carbonation rate. Data demonstrates that carbonation in BCA-amended reactors remained limited by CO2 supply, implying further acceleration is possible. PMID:26829491

  10. Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas

    Energy Technology Data Exchange (ETDEWEB)

    Devenney, Martin [Calera Corporation, Moss Landing, CA (United States); Gilliam, Ryan [Calera Corporation, Moss Landing, CA (United States); Seeker, Randy [Calera Corporation, Moss Landing, CA (United States)

    2015-06-30

    The objective of this project was to demonstrate an innovative process to mineralize CO2 from flue gas directly to reactive carbonates and maximize the value and versatility of its beneficial use products. The program scope includes the design, construction, and testing of a CO2 Conversion to Material Products (CCMP) Pilot Demonstration Plant utilizing CO2 from the flue gas of a power production facility in Moss Landing, CA as well as flue gas from coal combustion. This final report details all development, analysis, design and testing of the project. Also included in the final report are an updated Techno-Economic Analysis and CO2 Lifecycle Analysis. The subsystems included in the pilot demonstration plant are the mineralization subsystem, the Alkalinity Based on Low Energy (ABLE) subsystem, the waste calcium oxide processing subsystem, and the fiber cement board production subsystem. The fully integrated plant was proven to be capable of capturing CO2 from various sources (gas and coal) and mineralizing it into a reactive calcium carbonate binder and subsequently producing commercial size (4ftx8ft) fiber cement boards. The final report provides a description of the “as built” design of these subsystems and the results of the commissioning activities that have taken place to confirm operability. The report also discusses the results of the fully integrated operation of the facility. Fiber cement boards have been produced in this facility exclusively using reactive calcium carbonate from captured CO2 from flue gas. These boards meet all US and China appropriate acceptance standards. Use demonstrations for these boards are now underway.

  11. Microbially mediated mineral carbonation

    Science.gov (United States)

    Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2010-12-01

    Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O → (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily

  12. On the effect of aqueous Ca on magnesite growth - Insight into trace element inhibition of carbonate mineral precipitation

    Science.gov (United States)

    Berninger, Ulf-Niklas; Jordan, Guntram; Lindner, Michael; Reul, Alexander; Schott, Jacques; Oelkers, Eric H.

    2016-04-01

    Motivated by the strong effect of aqueous Mg on calcite growth rates, this study used hydrothermal atomic force microscopy (HAFM) and hydrothermal mixed-flow reactor (HMFR) experiments to explore the effect of aqueous Ca on magnesite growth kinetics at 100 °C and pH ∼7.7. Obtuse step velocities on (1 0 4) surfaces during magnesite growth were measured to be 4 ± 3 nm/s at fluid saturation states, equal to the ion activity quotient divided by the equilibrium constant for the magnesite hydrolysis reaction, of 86-117. These rates do not vary systematically with aqueous Ca concentration up to 3 × 10-3 mol/kg. Magnesite growth rates determined by HAFM are found to be negligibly affected by the presence of aqueous Ca at these saturation states and are largely consistent with those previously reported in aqueous Ca-free systems by Saldi et al. (2009) and Gautier et al. (2015). Similarly, magnesite growth rates measured by HMFR exhibit no systematic variation on aqueous Ca concentrations. Rates in this study, however, were extended to higher degrees of fluid supersaturation with respect to magnesite than previous studies. All measured HMFR rates can be accurately described taking account the combined effects of both the spiral growth and two dimensional nucleation/growth mechanisms. Despite the lack of a clear effect of aqueous Ca on magnesite growth rates, Raman spectroscopy confirmed the incorporation of up to 8 mol percent of Ca2+ into the growing magnesite structure.

  13. Carbon dioxide sequestration by mineral carbonation

    OpenAIRE

    Huijgen, W.J.J.

    2007-01-01

    The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept behind mineral CO2 sequestration is the mimicking of natural weathering processes in which calcium or magnesium containing minerals react with gaseous CO2 and form solid calcium or magnesium carbonate...

  14. Beneficial role of ZnO photocatalyst supported with porous activated carbon for the mineralization of alizarin cyanin green dye in aqueous solution

    OpenAIRE

    P. Muthirulan; M. Meenakshisundararam; Kannan, N

    2013-01-01

    The present investigation depicts the development of a simple and low cost method for the removal of color from textile dyeing and printing wastewater using ZnO as photocatalyst supported with porous activated carbon (AC). Photocatalytic degradation studies were carried out for water soluble toxic alizarin cyanin green (ACG) dye in aqueous suspension along with activated carbon (AC) as co-adsorbent. Different parameters like concentration of ACG dye, irradiation time, catalyst concentration a...

  15. Beneficial role of ZnO photocatalyst supported with porous activated carbon for the mineralization of alizarin cyanin green dye in aqueous solution

    Directory of Open Access Journals (Sweden)

    P. Muthirulan

    2013-11-01

    Full Text Available The present investigation depicts the development of a simple and low cost method for the removal of color from textile dyeing and printing wastewater using ZnO as photocatalyst supported with porous activated carbon (AC. Photocatalytic degradation studies were carried out for water soluble toxic alizarin cyanin green (ACG dye in aqueous suspension along with activated carbon (AC as co-adsorbent. Different parameters like concentration of ACG dye, irradiation time, catalyst concentration and pH have also been studied. The pseudo first order kinetic equation was found to be applicable in the present dye-catalyst systems. It was observed that photocatalytic degradation by ZnO along with AC was a more effective and faster mode of removing ACG from aqueous solutions than the ZnO alone.

  16. Carbon dioxide sequestration by mineral carbonation

    NARCIS (Netherlands)

    Huijgen, W.J.J.

    2007-01-01

    The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept beh

  17. Evaluating the seismic risk of mineral carbon sequestration

    Science.gov (United States)

    Balcerak, Ernie

    2013-04-01

    Geologic carbon sequestration, in which carbon is captured and stored underground, has been proposed as one way to mitigate the climatic effects of carbon dioxide emissions. One method of geologic carbon sequestration is to inject carbon dioxide in aqueous solution into rocks. However, as the solution fills the pore space in the rocks, the fluid pressure on the rocks increases, potentially increasing the risk of earthquakes. Another option would be to inject carbon dioxide solutions into mafic rocks; the silicate minerals in these rocks react with the carbon dioxide, leaving solid carbonate reaction products, which decrease the amount of pore fluid.

  18. A Novel Approach To Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. McKelvy; Andrew V. G. Chizmeshya; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

    2006-06-21

    Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. Herein, we report our second year progress in exploring a novel approach that offers the potential to substantially enhance carbonation reactivity while bypassing pretreatment activation. As our second year progress is intimately related to our earlier work, the report is presented in that context to provide better overall understanding of the progress made. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly

  19. Ultrasound-Intensified Mineral Carbonation

    OpenAIRE

    Santos, Rafael; François, Davy; Mertens, Gilles; Elsen, Jan; Van Gerven, Tom

    2013-01-01

    Several aspects of ultrasound-assisted mineral carbonation were investigated in this work. The objectives were to intensify the CO2 sequestration process to improve reaction kinetics and maximal conversion. Stainless steel slags, derived from the Argon Oxygen Decarburization (AOD) and Continuous Casting / Ladle Metallurgy (CC/LM) refining steps, were used for assessing the technical feasibility of this concept, as they are potential carbon sinks and can benefit from reduction in alkalinity (p...

  20. Novel biological approaches to carbon mineralization

    Science.gov (United States)

    Power, Ian; Kenward, Paul; Harrison, Anna; Dipple, Gregory; Raudsepp, Mati; Wilson, Siobhan; Southam, Gordon

    2015-04-01

    Innovative approaches for accelerating and manipulating fundamental geochemical processes are necessary to develop carbon mineralization as a viable strategy for the mitigation of greenhouse gas emissions. Mg-carbonate formation is of interest for both ex situ and in situ CO2 sequestration strategies1. Accordingly, we have investigated approaches to accelerate these water-rock reactions that produce Mg-carbonate minerals using biological approaches. For instance, CO2-limited conditions are encountered in many systems relevant to CO2 sequestration and represent a severe limitation on carbon mineralization. In carbonation experiments, the supply of CO2 was increased with the use of carbonic anhydrase, an enzyme that catalyzes the hydration of aqueous CO2. The presence of carbonic anhydrase had a dramatic impact on carbonation rates of brucite [Mg(OH)2]2, a mineral of interest for carbon sequestration3. In a CO2-rich aqueous environment, cyanobacteria were able to induce hydrated Mg-carbonate precipitation in microcosm experiments through the alkalinization of their microenvironment and concentration of cations on their cell membranes, which also provide regularly spaced, chemically identical sites for mineral nucleation4. In both lines of investigation, the resulting precipitates were metastable hydrated Mg-carbonate minerals rather then magnesite [MgCO3], the most stable Mg-carbonate and therefore the preferred product forsequestering CO2. Consequently, we have investigated approaches to improve magnesite precipitation rate in these low temperature environments. Inopportunely, rates of magnesite precipitation are severely limited at temperatures below 60 ° C due to the strong hydration of Mg2+ ions in solution5. Yet, carboxyl functional groups (R-COOH) are able to cause desolvation of Mg2+ ions6,7. In microcosm experiments using polystyrene microspheres with a high density of carboxyl groups, we were able to precipitate magnesite at room temperature from slightly

  1. mineral sequestration by wollastonite carbonation

    Science.gov (United States)

    Ding, Wenjin; Fu, Liangjie; Ouyang, Jing; Yang, Huaming

    2014-07-01

    In this paper, we demonstrated a new approach to CO2 mineral sequestration using wollastonite carbonation assisted by sulfuric acid and ammonia. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and 29Si nuclear magnetic resonance. The change in Gibbs free energy from -223 kJ/mol for the leaching reaction of wollastonite to -101 kJ/mol for the carbonation reaction indicated that these two reactions can proceed spontaneously. The leached and carbonated wollastonite showed fibrous bassanite and granular calcium carbonate, respectively, while the crystal structure of pristine wollastonite was destroyed and the majority of the Ca2+ in pristine wollastonite leached. The chemical changes in the phases were monitored during the whole process. A high carbonation rate of 91.1 % could be obtained under the action of sulfuric acid and ammonia at 30 °C at normal atmospheric pressure, indicating its potential use for CO2 sequestration.

  2. Ultrasound-intensified mineral carbonation

    International Nuclear Information System (INIS)

    Several aspects of ultrasound-assisted mineral carbonation were investigated in this work. The objectives were to intensify the CO2 sequestration process to improve reaction kinetics and maximal conversion. Stainless steel slags, derived from the Argon Oxygen Decarburization (AOD) and Continuous Casting/Ladle Metallurgy (CC/LM) refining steps, were used for assessing the technical feasibility of this concept, as they are potential carbon sinks and can benefit from reduction in alkalinity (pH) by mineral carbonation. Ultrasound was applied by use of an ultrasound horn into the reaction slurry, where mineral carbonation reaction took place at 50 °C for up to 4 h; comparison was made to solely mechanically mixed process. It was found that sonication increases the reaction rate after the initial stage, and permits achieving higher carbonate conversion and lower pH. AOD slag conversion increased from 30% to 49%, and pH decreased from 10.6 to 10.1; CC slag conversion increased from 61% to 73% and pH decreased from 10.8 to 9.9. The enhancement effect of ultrasound was attributed to the removal of passivating layers (precipitated calcium carbonate and depleted silica) that surround the unreacted particle core and inhibit mass transfer. Significant particle size reduction was observed for sonicated powders, compared to particle size growth in the case of stirring-only; D[4,3] values increased without sonication by 74% and 50%, and decreased with sonication by 64% and 52%, respectively for AOD and CC slags. Considerations on scale-up of this technology, particularly with regards to energy efficiency, are also discussed. Highlights: ► Ultrasound increased CaO, AOD and CC slags mineral carbonation rates and conversions. ► Enhancement effect linked to removal of mass transfer inhibiting passivating layers. ►Carbonated particle size grew with stirring-only, and decreased with sonication. ► Lower pH of slags with greater carbonation extent can reduce heavy metal leaching

  3. A Novel Approach to Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost

    Energy Technology Data Exchange (ETDEWEB)

    Andrew V. G. Chizmeshya; Michael J. McKelvy; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

    2007-06-21

    Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly-stirred/circulating carbonation. We are exploring the mechanisms that govern carbonation reactivity and the impact that (1) modeling/controlling the slurry fluid-flow conditions, (2) varying the aqueous ion species/size and concentration (e.g., Li+, Na+, K+, Rb+, Cl-, HCO{sub 3}{sup -}), and (3) incorporating select sonication offer to enhance exfoliation and carbonation. Thus

  4. Observations on the Solubility of Skeletal Carbonates in Aqueous Solutions.

    Science.gov (United States)

    Chave, K E; Deffeyes, K S; Weyl, P K; Garrels, R M; Thompson, M E

    1962-07-01

    Carbonate skeletal materials of marine organisms exhibit a wide range of solubilities in aqueous solutions. In most cases, the dissolution of the carbonate mineral is irreversible and therefore the material can have no true equilibrium solubility. Relative solubilities have been measured in distilled water and in sea water. The least soluble mineral appears to be calcite with low magnesium content; the most soluble is calcite containing 20 to 30 percent MgCO(3) in solid solution. Aragonite has an intermediate solubility. PMID:17774123

  5. Carbon dioxide sequestration by mineral carbonation. Literature Review

    International Nuclear Information System (INIS)

    promising route available seems to be the direct aqueous route, for which reasonable reaction rates at feasible process conditions have been shown. Important aspects of mineral CO2 sequestration are the transport of the materials involved and the fate of the products. Transport costs can be minimised by transporting the carbon dioxide towards a mineral sequestration plant situated near the feedstock mine. The carbonated products can be used for mine reclamation and construction applications. Unfortunately, only few rough cost estimates have been published and detailed cost analyses of the most promising process routes are absent in the literature. Therefore, at present, there is insufficient knowledge to conclude whether a cost-effective and energetically acceptable process will be feasible. Mineral carbon sequestration is a longer-term option compared to other sequestration routes, but its fundamental advantages justify further research. Major issues that need to be resolved in order to enable large-scale implementation are the energy consumption of the process, the reaction rates and the environmental impact of mineral CO2 sequestration. Finally, the use of alkaline solid wastes as an alternative feedstock for calcium or magnesium is acknowledged and warrants further research

  6. Integrating Steel Production with Mineral Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Klaus Lackner; Paul Doby; Tuncel Yegulalp; Samuel Krevor; Christopher Graves

    2008-05-01

    The objectives of the project were (i) to develop a combination iron oxide production and carbon sequestration plant that will use serpentine ores as the source of iron and the extraction tailings as the storage element for CO2 disposal, (ii) the identification of locations within the US where this process may be implemented and (iii) to create a standardized process to characterize the serpentine deposits in terms of carbon disposal capacity and iron and steel production capacity. The first objective was not accomplished. The research failed to identify a technique to accelerate direct aqueous mineral carbonation, the limiting step in the integration of steel production and carbon sequestration. Objective (ii) was accomplished. It was found that the sequestration potential of the ultramafic resource surfaces in the US and Puerto Rico is approximately 4,647 Gt of CO2 or over 500 years of current US production of CO2. Lastly, a computer model was developed to investigate the impact of various system parameters (recoveries and efficiencies and capacities of different system components) and serpentinite quality as well as incorporation of CO2 from sources outside the steel industry.

  7. Mineralization of Carbon Dioxide: Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, V; Soong, Y; Carney, C; Rush, G; Nielsen, B; O' Connor, W

    2015-01-01

    CCS research has been focused on CO2 storage in geologic formations, with many potential risks. An alternative to conventional geologic storage is carbon mineralization, where CO2 is reacted with metal cations to form carbonate minerals. Mineralization methods can be broadly divided into two categories: in situ and ex situ. In situ mineralization, or mineral trapping, is a component of underground geologic sequestration, in which a portion of the injected CO2 reacts with alkaline rock present in the target formation to form solid carbonate species. In ex situ mineralization, the carbonation reaction occurs above ground, within a separate reactor or industrial process. This literature review is meant to provide an update on the current status of research on CO2 mineralization. 2

  8. Microbially mediated carbon mineralization: Geoengineering a carbon-neutral mine

    Science.gov (United States)

    Power, I. M.; McCutcheon, J.; Harrison, A. L.; Wilson, S. A.; Dipple, G. M.; Southam, G.

    2013-12-01

    Ultramafic and mafic mine tailings are a potentially valuable feedstock for carbon mineralization, affording the mining industry an opportunity to completely offset their carbon emissions. Passive carbon mineralization has previously been documented at the abandoned Clinton Creek asbestos mine, and the active Diavik diamond mine and Mount Keith nickel mine, yet the majority of tailings remain unreacted. Examples of microbe-carbonate interactions at each mine suggest that biological pathways could be harnessed to promote carbon mineralization. In suitable environmental conditions, microbes can mediate geochemical processes to accelerate mineral dissolution, increase the supply of carbon dioxide (CO2), and induce carbonate precipitation, all of which may accelerate carbon mineralization. Tailings mineralogy and the availability of a CO2 point source are key considerations in designing tailings storage facilities (TSF) for optimizing carbon mineralization. We evaluate the efficacy of acceleration strategies including bioleaching, biologically induced carbonate precipitation, and heterotrophic oxidation of waste organics, as well as abiotic strategies including enhancing passive carbonation through modifying tailings management practices and use of CO2 point sources (Fig. 1). With the aim of developing carbon-neutral mines, implementation of carbon mineralization strategies into TSF design will be driven by economic incentives and public pressure for environmental sustainability in the mining industry. Figure 1. Schematic illustrating geoengineered scenarios for carbon mineralization of ultramafic mine tailings. Scenarios A and B are based on non-point and point sources of CO2, respectively.

  9. A literature review of actinide-carbonate mineral interactions

    International Nuclear Information System (INIS)

    Chemical retardation of actinides in groundwater systems is a potentially important mechanism for assessing the performance of the Waste Isolation Pilot Plant (WIPP), a facility intended to demonstrate safe disposal of transuranic waste. Rigorous estimation of chemical retardation during transport through the Culebra Dolomite, a water-bearing unit overlying the WIPP, requires a mechanistic understanding of chemical reactions between dissolved elements and mineral surfaces. This report represents a first step toward this goal by examining the literature for pertinent experimental studies of actinide-carbonate interactions. A summary of existing models is given, along with the types of experiments on which these models are based. Articles pertaining to research into actinide interactions with carbonate minerals are summarized. Select articles involving trace element-carbonate mineral interactions are also reviewed and may serve as templates for future research. A bibliography of related articles is included. Americium(III), and its nonradioactive analog neodymium(III), partition strongly from aqueous solutions into carbonate minerals. Recent thermodynamic, kinetic, and surface studies show that Nd is preferentially removed from solution, forming a Nd-Ca carbonate solid solution. Neptunium(V) is rapidly removed from solution by carbonates. Plutonium incorporation into carbonates is complicated by multiple oxidation states. Little research has been done on the radium(H) and thorium(IV) carbonate systems. Removal of uranyl ion from solution by calcite is limited to monolayer surface coverage

  10. Cyanobacteria as Biocatalysts for Carbonate Mineralization

    OpenAIRE

    Christer Jansson; Ajo-Franklin, Caroline M.; Kamennaya, Nina A.; Trent Northen

    2012-01-01

    Microbial carbonate mineralization is widespread in nature and among microorganisms, and of vast ecological and geological importance. However, our understanding of the mechanisms that trigger and control processes such as calcification, i.e., mineralization of CO2 to calcium carbonate (CaCO3), is limited and literature on cyanobacterial calcification is oftentimes bewildering and occasionally controversial. In cyanobacteria, calcification may be intimately associated with the carbon dioxide-...

  11. Cyanobacteria as Biocatalysts for Carbonate Mineralization

    Directory of Open Access Journals (Sweden)

    Christer Jansson

    2012-10-01

    Full Text Available Microbial carbonate mineralization is widespread in nature and among microorganisms, and of vast ecological and geological importance. However, our understanding of the mechanisms that trigger and control processes such as calcification, i.e., mineralization of CO2 to calcium carbonate (CaCO3, is limited and literature on cyanobacterial calcification is oftentimes bewildering and occasionally controversial. In cyanobacteria, calcification may be intimately associated with the carbon dioxide-(CO2 concentrating mechanism (CCM, a biochemical system that allows the cells to raise the concentration of CO2 at the site of the carboxylating enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco up to 1000-fold over that in the surrounding medium. A comprehensive understanding of biologically induced carbonate mineralization is important for our ability to assess its role in past, present, and future carbon cycling, interpret paleontological data, and for evaluating the process as a means for biological carbon capture and storage (CCS. In this review we summarize and discuss the metabolic, physiological and structural features of cyanobacteria that may be involved in the reactions leading to mineral formation and precipitation, present a conceptual model of cyanobacterial calcification, and, finally, suggest practical applications for cyanobacterial carbonate mineralization.

  12. Impacts of Nickel Nanoparticles on Mineral Carbonation

    Directory of Open Access Journals (Sweden)

    Marius Bodor

    2014-01-01

    Full Text Available This work presents experimental results regarding the use of pure nickel nanoparticles (NiNP as a mineral carbonation additive. The aim was to confirm if the catalytic effect of NiNP, which has been reported to increase the dissolution of CO2 and the dissociation of carbonic acid in water, is capable of accelerating mineral carbonation processes. The impacts of NiNP on the CO2 mineralization by four alkaline materials (pure CaO and MgO, and AOD and CC steelmaking slags, on the product mineralogy, on the particle size distribution, and on the morphology of resulting materials were investigated. NiNP-containing solution was found to reach more acidic pH values upon CO2 bubbling, confirming a higher quantity of bicarbonate ions. This effect resulted in acceleration of mineral carbonation in the first fifteen minutes of reaction time when NiNP was present. After this initial stage, however, no benefit of NiNP addition was seen, resulting in very similar carbonation extents after one hour of reaction time. It was also found that increasing solids content decreased the benefit of NiNP, even in the early stages. These results suggest that NiNP has little contribution to mineral carbonation processes when the dissolution of alkaline earth metals is rate limiting.

  13. Aqueous solution dispersement of carbon nanotubes

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  14. Silicate production and availability for mineral carbonation.

    Science.gov (United States)

    Renforth, P; Washbourne, C-L; Taylder, J; Manning, D A C

    2011-03-15

    Atmospheric carbon dioxide sequestered as carbonates through the accelerated weathering of silicate minerals is proposed as a climate change mitigation technology with the potential to capture billions of tonnes of carbon per year. Although these materials can be mined expressly for carbonation, they are also produced by human activities (cement, iron and steel making, coal combustion, etc.). Despite their potential, there is poor global accounting of silicates produced in this way. This paper presents production estimates (by proxy) of various silicate materials including aggregate and mine waste, cement kiln dust, construction and demolition waste, iron and steel slag, and fuel ash. Approximately 7-17 billion tonnes are produced globally each year with an approximate annual sequestration potential of 190-332 million tonnes C. These estimates provide justification for additional research to accurately quantify the contemporary production of silicate minerals and to determine the location and carbon capture potential of historic material accumulations. PMID:21332128

  15. Estimation of palaeohydrochemical conditions using carbonate minerals

    Science.gov (United States)

    Amamiya, H.; Mizuno, T.; Iwatsuki, T.; Yuguchi, T.; Murakami, H.; Saito-Kokubu, Y.

    2014-12-01

    The long-term evolution of geochemical environment in deep underground is indispensable research subject for geological disposal of high-level radioactive waste, because the evolution of geochemical environment would impact migration behavior of radionuclides in deep underground. Many researchers have made efforts previously to elucidate the geochemical environment within the groundwater residence time based on the analysis of the actual groundwater. However, it is impossible to estimate the geochemical environment for the longer time scale than the groundwater residence time in this method. In this case, analysis of the chemical properties of secondary minerals are one of useful method to estimate the paleohydrochemical conditions (temperature, salinity, pH and redox potential). In particular, carbonate minerals would be available to infer the long-term evolution of hydrochemical for the following reasons; -it easily reaches chemical equilibrium with groundwater and precipitates in open space of water flowing path -it reflects the chemical and isotopic composition of groundwater at the time of crystallization We reviewed the previous studies on carbonate minerals and geochemical conditions in deep underground and estimated the hydrochemical characteristics of past groundwater by using carbonate minerals. As a result, it was found that temperature and salinity of the groundwater during crystallization of carbonate minerals were evaluated quantitatively. On the other hand, pH and redox potential can only be understood qualitatively. However, it is suggested that the content of heavy metal elements such as manganese, iron and uranium, and rare earth elements in the carbonate minerals are useful indicators for estimating redox potential. This study was carried out under a contract with METI (Ministry of Economy, Trade and Industry) as part of its R&D supporting program for developing geological disposal technology.

  16. Mineral Carbonation Employing Ultramafic Mine Waste

    Science.gov (United States)

    Southam, G.; McCutcheon, J.; Power, I. M.; Harrison, A. L.; Wilson, S. A.; Dipple, G. M.

    2014-12-01

    Carbonate minerals are an important, stable carbon sink being investigated as a strategy to sequester CO2 produced by human activity. A natural playa (Atlin, BC, CAN) that has demonstrated the ability to microbially-accelerate hydromagnesite formation was used as an experimental model. Growth of microbial mats from Atlin, in a 10 m long flow-through bioreactor catalysed hydromagnesite precipitation under 'natural' conditions. To enhance mineral carbonation, chrysotile from the Clinton Creek Asbestos Mine (YT, CAN) was used as a target substrate for sulphuric acid leaching, releasing as much as 94% of the magnesium into solution via chemical weathering. This magnesium-rich 'feedstock' was used to examine the ability of the microbialites to enhance carbonate mineral precipitation using only atmospheric CO2 as the carbon source. The phototrophic consortium catalysed the precipitation of platy hydromagnesite [Mg5(CO3)4(OH)2·4H2O] accompanied by magnesite [MgCO3], aragonite [CaCO3], and minor dypingite [Mg5(CO3)4(OH)2·5H2O]. Scanning Electron Microscopy-Energy Dispersive Spectroscopy indicated that cell exteriors and extracellular polymeric substances (EPS) served as nucleation sites for carbonate precipitation. In many cases, entire cyanobacteria filaments were entombed in magnesium carbonate coatings, which appeared to contain a framework of EPS. Cell coatings were composed of small crystals, which intuitively resulted from rapid crystal nucleation. Excess nutrient addition generated eutrophic conditions in the bioreactor, resulting in the growth of a pellicle that sealed the bioreactor contents from the atmosphere. The resulting anaerobic conditions induced fermentation and subsequent acid generation, which in turn caused a drop in pH to circumneutral values and a reduction in carbonate precipitation. Monitoring of the water chemistry conditions indicated that a high pH (> 9.4), and relatively high concentrations of magnesium (> 3000 ppm), compared with the natural

  17. On Serpentinization and Mineral Carbonation of Serpentinite (Invited)

    Science.gov (United States)

    Klein, F.; Garrido, C. J.

    2010-12-01

    Mineral carbonation of serpentinite is chiefly controlled by temperature, protolith composition, and solute activities of intergranular fluids. Despite the enormous carbonation potential of serpentinite, to date the mutual relations of these parameters have received relatively little attention. We present new activity-activity diagrams and geochemical reaction path models to improve our understanding of heterogeneous phase equilibria during mineral carbonation of serpentinite and dunite in a wide range of temperatures (100 to 400 °C). Our calculations highlight the pivotal roles that the activities of aqueous carbon dioxide (aCO2,aq) and silica (aSiO2,aq) play. At low temperatures there is ample thermodynamic driving force for mineral carbonation as the gradients in aCO2,aq and aSiO2,aq set by quartz-magnesite (listvenite) and serpentine-brucite (serpentinite) phase equilibria are extremely steep. With increasing temperature the gradients in aSiO2,aq and aCO2,aq diminish because the stability fields of brucite, serpentine and talc expand towards higher aCO2,aq. Accordingly, the stability field of magnesite contracts. Moreover, the solubility of quartz increases with increasing temperature, which shifts the quartz-magnesite equilibrium to higher aCO2,aq. The combined of effects of both, shrinking geochemical potential gradients and increasing quartz solubility hamper mineral carbonation of serpentinite above 300 °C. Field observations of carbonated serpentinite reveal a rather simple sequence of arrested carbonation reactions, which is typically fossilized as spatially distinct metasomatic zones. A zone of serpentinized peridotite is followed by a zone of serpentine + carbonate, then talc + carbonate and finally quartz + carbonate. Our modeling results are consistent with these observations and suggest that quartz-carbonate alteration is limited to rather low or moderate alteration temperatures while talc-carbonate alteration can take place at much higher

  18. Biomimetic mineralization: encapsulation in calcium carbonate shells

    OpenAIRE

    Oliveira, Susana Costa de

    2015-01-01

    Calcium carbonate biomineralization is a self-assembly process that has been studied to be applied in the biomedical field to encapsulate biomolecules. Advantages of engineering mineral capsules include improved drug loading efficiencies and protection against external environment. However, common production methods result in heterogeneous capsules and subject biomolecules to heat and vibration which cause irreversible damage. To overcome these issues, a microfluidic device was designed, m...

  19. Thermodynamic constraints on mineral carbonation of serpentinized peridotite

    Science.gov (United States)

    Klein, Frieder; Garrido, Carlos J.

    2011-10-01

    Carbonation of serpentinite appears to be a promising process to mitigate rising concentrations of atmospheric CO 2. However, given that chemical affinities of mineral carbonation reactions in serpentinized peridotite change drastically with temperature, protolith and the activities of dissolved constituents, this process is incompletely understood. In this report numerical models are used to investigate the heterogeneous phase equilibria and the speciation of intergranular fluids during mineral carbonation of serpentinite/dunite at 100, 200, 300 and 400 °C. The results suggest that temperature-dependent activity gradients of both aqueous carbon dioxide (aCO 2,aq) and aqueous silica (aSiO 2,aq) determine the carbonation potential of serpentinite. At low to moderate temperatures there is ample thermodynamic driving force for the carbonation of serpentinite, as the gradients in aSiO 2,aq and aCO 2,aq set between talc-quartz-magnesite and serpentine-brucite equilibria are steepest. With increasing temperature these activity gradients become smaller because the stability fields of brucite, serpentine and talc expand toward higher aCO 2,aq and aSiO 2,aq while the stability field of magnesite contracts. In addition, the enhanced solubility of quartz toward higher temperatures shifts the talc-quartz-magnesite equilibrium to very high aCO 2,aq. Field observations of carbonated serpentinite reveal a rather simple sequence of arrested carbonation reactions, which is typically fossilized as spatially distinct metasomatic zones. A zone of serpentinized peridotite is followed by a zone of serpentine + carbonate, then talc + carbonate and finally quartz + carbonate. Our modeling results not only reproduce these observations, they also suggest that complete carbonation is favored at low to moderate temperatures. Since complete carbonation of serpentinite is achieved at relatively small fluid to rock ratios at temperatures ≤ 200 °C, prolonged fluid influx at low temperatures

  20. Aqueous suspensions of natural swelling clay minerals. 2. Rheological characterization.

    Science.gov (United States)

    Paineau, Erwan; Michot, Laurent J; Bihannic, Isabelle; Baravian, Christophe

    2011-06-21

    We report in this article a comprehensive investigation of the viscoelastic behavior of different natural colloidal clay minerals in aqueous solution. Rheological experiments were carried out under both dynamic and steady-state conditions, allowing us to derive the elasticity and yield stress. Both parameters can be renormalized for all sizes, ionic strength, and type of clay using in a first approach only the volume of the particles. However, applying such a treatment to various clays of similar shapes and sizes yields differences that can be linked to the repulsion strength and charge location in the swelling clays. The stronger the repulsive interactions, the better the orientation of clay particles in flows. In addition, a master linear relationship between the elasticity and yield stress whose value corresponds to a critical deformation of 0.1 was evidenced. Such a relationship may be general for any colloidal suspension of anisometric particles as revealed by the analysis of various experimental data obtained on either disk-shaped or lath- and rod-shaped particles. The particle size dependence of the sol-gel transition was also investigated in detail. To understand why suspensions of larger particles gel at a higher volume fraction, we propose a very simplified view based on the statistical hydrodynamic trapping of a particle by an another one in its neighborhood upon translation and during a short period of time. We show that the key parameter describing this hydrodynamic trapping varies as the cube of the average diameter and captures most features of the sol-gel transition. Finally, we pointed out that in the high shear limit the suspension viscosity is still closely related to electrostatic interactions and follows the same trends as the viscoelastic properties. PMID:21591697

  1. Atom probe tomography (APT) of carbonate minerals.

    Science.gov (United States)

    Pérez-Huerta, Alberto; Laiginhas, Fernando; Reinhard, David A; Prosa, Ty J; Martens, Rich L

    2016-01-01

    Atom probe tomography (APT) combines the highest spatial resolution with chemical data at atomic scale for the analysis of materials. For geological specimens, the process of field evaporation and molecular ion formation and interpretation is not yet entirely understood. The objective of this study is to determine the best conditions for the preparation and analysis by APT of carbonate minerals, of great importance in the interpretation of geological processes, focusing on the bulk chemical composition. Results show that the complexity of the mass spectrum is different for calcite and dolomite and relates to dissimilarities in crystalochemical parameters. In addition, APT bulk chemistry of calcite closely matches the expected stoichiometry but fails to provide accurate atomic percentages for elements in dolomite under the experimental conditions evaluated in this work. For both calcite and dolomite, APT underestimates the amount of oxygen based on their chemical formula, whereas it is able to detect small percentages of elemental substitutions in crystal lattices. Overall, our results demonstrate that APT of carbonate minerals is possible, but further optimization of the experimental parameters are required to improve the use of atom probe tomography for the correct interpretation of mineral geochemistry. PMID:26519815

  2. Carbon dioxide sequestration by mineral carbonation. Feasibility of enhanced natural weathering as a CO2 emission reduction technology

    International Nuclear Information System (INIS)

    /or thermal activation). The only available pre-treatment option that has proven to be energetically and potentially economically feasible is conventional grinding. In Chapter 2 the mechanisms of aqueous steel slag carbonation are studied experimentally. Process variables, such as particle size, temperature, and carbon dioxide pressure are systematically varied and their influence on the carbonation rate is investigated. In Chapter 3 the mechanisms of aqueous steel slag carbonation are further investigated, together with the environmental properties of the (carbonated) steel slag. In Chapter 4, the mechanisms of aqueous wollastonite carbonation as a possible carbon dioxide sequestration process are investigated experimentally by systematic variation of the reaction temperature, CO2 pressure, particle size, reaction time, liquid-to-solid ratio, and agitation power. The obtained insight in the reaction mechanisms in Chapter 2 - 4 is used as the (experimental) basis for the energetic and economic assessment of CO2 sequestration by mineral carbonation in Chapters 5 and 6. The energy consumption of a mineral carbonation plant causes extra CO2 emissions and, thereby, reduces the net amount of CO2 sequestered by the process. Chapter 5 studies the energetic CO2 sequestration efficiency of the aqueous mineral carbonation in dependence of various process variables using either wollastonite or steel slag as feedstock. A flowsheet of a mineral carbonation plant is designed and the process is simulated to determine the properties of streams as well as the power and heat consumption of the process equipment. In Chapter 6 a cost evaluation of CO2 sequestration by aqueous mineral carbonation is presented, using either wollastonite or steel slag as feedstock. On the basis of a basic design of the major process equipment, the total investment costs are estimated with the help of publicly available literature and a factorial cost estimation method. Subsequently, the sequestration costs are

  3. SkyMine Carbon Mineralization Pilot Project

    Energy Technology Data Exchange (ETDEWEB)

    Christenson, Norm; Walters, Jerel

    2014-12-31

    This Topical Report addresses accomplishments achieved during Phase 2b of the SkyMine® Carbon Mineralization Pilot Project. The primary objectives of this project are to design, construct, and operate a system to capture CO2 from a slipstream of flue gas from a commercial coal-fired cement kiln, convert that CO2 to products having commercial value (i.e., beneficial use), show the economic viability of the CO2 capture and conversion process, and thereby advance the technology to the point of readiness for commercial scale demonstration and deployment. The overall process is carbon negative, resulting in mineralization of CO2 that would otherwise be released into the atmosphere. The project will also substantiate market opportunities for the technology by sales of chemicals into existing markets, and identify opportunities to improve technology performance and reduce costs at the commercial scale. The project is being conducted in two phases. The primary objectives of Phase 1 were to evaluate proven SkyMine® process chemistry for commercial pilot-scale operation and complete the preliminary design for the pilot plant to be built and operated in Phase 2, complete a NEPA evaluation, and develop a comprehensive carbon life cycle analysis. The objective of Phase 2b was to build the pilot plant to be operated and tested in Phase 2c.

  4. Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

    Science.gov (United States)

    Wilcox, J.; Kirchofer, A.

    2014-12-01

    Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency

  5. Adsorption of Carboxylic Acids on Reservoir Minerals from Organic and Aqueous Phase

    DEFF Research Database (Denmark)

    Madsen, Lene; Lind, Ida

    1998-01-01

    Adsorption of organic acids onto North Sea chalk and pure minerals from a hydrocarbon phase and an aqueous phase show that the maximum adsorption is larger for calcite than for silicate surfaces in the hydrocarbon phase. The opposite is observed, however, in the aqueous phase. This suggests that...

  6. Molecular simulation of carbon dioxide, brine, and clay mineral interactions and determination of contact angles.

    Science.gov (United States)

    Tenney, Craig M; Cygan, Randall T

    2014-01-01

    Capture and subsequent geologic storage of CO2 in deep brine reservoirs plays a significant role in plans to reduce atmospheric carbon emission and resulting global climate change. The interaction of CO2 and brine species with mineral surfaces controls the ultimate fate of injected CO2 at the nanoscale via geochemistry, at the pore-scale via capillary trapping, and at the field-scale via relative permeability. We used large-scale molecular dynamics simulations to study the behavior of supercritical CO2 and aqueous fluids on both the hydrophilic and hydrophobic basal surfaces of kaolinite, a common clay mineral. In the presence of a bulk aqueous phase, supercritical CO2 forms a nonwetting droplet above the hydrophilic surface of kaolinite. This CO2 droplet is separated from the mineral surface by distinct layers of water, which prevent the CO2 droplet from interacting directly with the mineral surface. Conversely, both CO2 and H2O molecules interact directly with the hydrophobic surface of kaolinite. In the presence of bulk supercritical CO2, nonwetting aqueous droplets interact with the hydrophobic surface of kaolinite via a mixture of adsorbed CO2 and H2O molecules. Because nucleation and precipitation of minerals should depend strongly on the local distribution of CO2, H2O, and ion species, these nanoscale surface interactions are expected to influence long-term mineralization of injected carbon dioxide. PMID:24410258

  7. Real Time Pore Structure Evolution during Olivine Mineral Carbonation

    Science.gov (United States)

    Zhu, W.; Fusseis, F.; Lisabeth, H. P.; Xiao, X.

    2014-12-01

    Aqueous carbonation of ultramafic rocks has been proposed as a promising method for long-term, secure sequestration of carbon dioxide. While chemical kinetics data indicate that carbonation reaction in olivine is one of the fastest among the mg-bearing minerals, in practice, the factors that limit the extent and rate of carbonation in ultramafic rocks are fluid supply and flux. On the one hand, reaction products could produce passivating layer that prohibits further reactions. On the other hand, the increases in solid volume during carbonation could lead to cracking and create new fluid paths. Whether carbonation in ultramafic rocks is self-limiting or self-sustaining has been hotly debated. Experimental evidence of precipitation of reaction products during olivine carbonation was reported. To date, reaction-driven cracking has not been observed. In this paper, we present the first real-time pore structure evolution data using the x-ray synchrotron microtomography. Sodium bicarbonate (NaHCO3) solution was injected into porous olivine aggregates and in-situ pore structure change during olivine carbonation at a constant confining pressure (12 MPa) and a temperature of 200oC was captured at 30 min. interval for ~160 hours. Shortly after the experiment started, filling-in of the existing pores by precipitation of reaction products was visible. The size of the in-fills kept increasing as reactions continued. After ~48 hours, cracking around the in-fill materials became visible. After ~60 hours, these cracks started to show a clear polygonal pattern, similar to the crack patterns usually seen on the surface of drying mud. After ~72 hours, some of the cracks coalesced into large fractures that cut-through the olivine aggregates. New fractures continued to develop and at the end of the experiment, the sample was completely disintegrated by these fractures. We also conducted nanotomography experiments on a sub-volume of the reacted olivine aggregate. Orthogonal sets of

  8. Photochemical processing of aqueous atmospheric brown carbon

    Science.gov (United States)

    Zhao, R.; Lee, A. K. Y.; Huang, L.; Li, X.; Yang, F.; Abbatt, J. P. D.

    2015-06-01

    Atmospheric brown carbon (BrC) is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report on a series of laboratory studies of photochemical processing of BrC in the aqueous phase, by direct photolysis and OH oxidation. Solutions of ammonium sulfate mixed with glyoxal (GLYAS) or methylglyoxal (MGAS) are used as surrogates for a class of secondary BrC mediated by imine intermediates. Three nitrophenol species, namely 4-nitrophenol, 5-nitroguaiacol and 4-nitrocatechol, were investigated as a class of water-soluble BrC originating from biomass burning. Photochemical processing induced significant changes in the absorptive properties of BrC. The imine-mediated BrC solutions exhibited rapid photo-bleaching with both direct photolysis and OH oxidation, with atmospheric half-lives of minutes to a few hours. The nitrophenol species exhibited photo-enhancement in the visible range during direct photolysis and the onset of OH oxidation, but rapid photo-bleaching was induced by further OH exposure on an atmospheric timescale of an hour or less. To illustrate the atmospheric relevance of this work, we also performed direct photolysis experiments on water-soluble organic carbon extracted from biofuel combustion samples and observed rapid changes in the optical properties of these samples as well. Overall, these experiments indicate that atmospheric models need to incorporate representations of atmospheric processing of BrC species to accurately model their radiative impacts.

  9. Microtribology of aqueous carbon nanotube dispersions

    KAUST Repository

    Kristiansen, Kai De Lange

    2011-09-23

    The tribological behavior of carbon nanotubes (CNTs) in aqueous humic acid (HA) solutions was studied using a surface forces apparatus (SFA) and shows promising lubricant additive properties. Adding CNTs to the solution changes the friction forces between two mica surfaces from "adhesion controlled" to "load controlled" friction. The coefficient of friction with either single-walled (SW) or multi-walled (MW) CNT dispersions is in the range 0.30-0.55 and is independent of the load and sliding velocity. More importantly, lateral sliding promotes a redistribution or accumulation, rather than squeezing out, of nanotubes between the surfaces. This accumulation reduced the adhesion between the surfaces (which generally causes wear/damage of the surfaces), and no wear or damage was observed during continuous shearing experiments that lasted several hours even under high loads (pressures â∼10 MPa). The frictional properties can be understood in terms of the Cobblestone Model where the friction force is related to the fraction of the adhesion energy dissipated during impacts of the nanoparticles. We also develop a simple generic model based on the van der Waals interactions between particles and surfaces to determine the relation between the dimensions of nanoparticles and their tribological properties when used as additives in oil- or water-based lubricants. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Nanokin: a geochemical computer model for dissolution, nucleation and growth of clay minerals in aqueous solutions

    International Nuclear Information System (INIS)

    A recent evolution of Water-Rock Interaction models including complex mineral phases like clay minerals: Clay minerals simulated as solid solution s The recent evolution of water-rock interaction models takes into account the ability of clay minerals to change their chemical composition along water-clay interaction processes, in relation with the possible variations of the aqueous chemical composition of natural fluids. The concept of solid solution has been used in our geochemical code KINDIS and coupled transport/ reaction model KIRMAT. Clay minerals are represented by generalized n-end-member solid solutions. The two codes are now producing mineral phases as solid solutions of n-end-members, at equilibrium with the aqueous reaction phase or under kinetic control if rate laws are available from experimental approach, or can be estimated. (authors)

  11. Adsorption of Acrylonitrile on Some Soils and Minerals from Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    WUDE-YI; N.MATSUE; 等

    1993-01-01

    Equilibrium and kinetic studies have been made on the adsorption of acrylonitrile(CH2=CHCN) on three soils and four minerals from aqueous solutions.It was shown that the organic matter was the major factor affecting the adsorption process in the soils.The conformity of the equilibrium data to linear type(one soil) and Langmuir type(two soils) isotherms indicated that different mechanisms were involved in the adsorption.This behavior appears bo be related to the hydrophobicity of soil organic matter due to their composition and E4/E6 ratio of humic acids.The adsorption kinetics were also different among the soils,indicating the difference in porosity of organic matter among the soils,and the kinetics strongly affected the adsorption capacity of soils for acrylonitrile.Acrylonitrile was slightly adsorbed from aqueous solutions on pyrophyllite with electrically neutral and hydrophobic nature,and practically not on montmorillonite and kaolinite saturated with Ca.However,much higher adsorption occurred on the zeolitized coal ash,probably caused by high organic carbon content(107g/kg).

  12. SkyMine Carbon Mineralization Pilot Project

    Energy Technology Data Exchange (ETDEWEB)

    Joe Jones; Clive Barton; Mark Clayton; Al Yablonsky; David Legere

    2010-09-30

    This Topical Report addresses accomplishments achieved during Phase 1 of the SkyMine{reg_sign} Carbon Mineralization Pilot Project. The primary objectives of this project are to design, construct, and operate a system to capture CO{sub 2} from a slipstream of flue gas from a commercial coal-fired cement kiln, convert that CO{sub 2} to products having commercial value (i.e., beneficial use), show the economic viability of the CO{sub 2} capture and conversion process, and thereby advance the technology to a point of readiness for commercial scale demonstration and proliferation. The project will also substantiate market opportunities for the technology by sales of chemicals into existing markets, and identify opportunities to improve technology performance and reduce costs at commercial scale. The primary objectives of Phase 1 of the project were to elaborate proven SkyMine{reg_sign} process chemistry to commercial pilot-scale operation and complete the preliminary design ('Reference Plant Design') for the pilot plant to be built and operated in Phase 2. Additionally, during Phase 1, information necessary to inform a DOE determination regarding NEPA requirements for the project was developed, and a comprehensive carbon lifecycle analysis was completed. These items were included in the formal application for funding under Phase 2. All Phase 1 objectives were successfully met on schedule and within budget.

  13. Mineral protection of soil carbon counteracted by root exudates

    Science.gov (United States)

    Keiluweit, Marco; Bougoure, Jeremy J.; Nico, Peter S.; Pett-Ridge, Jennifer; Weber, Peter K.; Kleber, Markus

    2015-06-01

    Multiple lines of existing evidence suggest that climate change enhances root exudation of organic compounds into soils. Recent experimental studies show that increased exudate inputs may cause a net loss of soil carbon. This stimulation of microbial carbon mineralization (`priming’) is commonly rationalized by the assumption that exudates provide a readily bioavailable supply of energy for the decomposition of native soil carbon (co-metabolism). Here we show that an alternate mechanism can cause carbon loss of equal or greater magnitude. We find that a common root exudate, oxalic acid, promotes carbon loss by liberating organic compounds from protective associations with minerals. By enhancing microbial access to previously mineral-protected compounds, this indirect mechanism accelerated carbon loss more than simply increasing the supply of energetically more favourable substrates. Our results provide insights into the coupled biotic-abiotic mechanisms underlying the `priming’ phenomenon and challenge the assumption that mineral-associated carbon is protected from microbial cycling over millennial timescales.

  14. Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

    Science.gov (United States)

    Ming, Douglas W.; Morris, R. V.; Golden, D. C.

    2011-01-01

    involved. The style of aqueous alteration (hydrolytic vs. acid sulfate) impacts which phases will form (e.g., oxides, oxysulfates, and oxyhydroxides). Knowledge on the formation processes of SRO phases in basaltic materials on Earth has allowed significant enhancement in our understanding of the aqueous processes at work on Mars. The 2011 Mars Science Laboratory (MSL) will provide an instrument suite that should improve our understanding of the mineralogical and chemical compositions of SRO phases. CheMin is an X-ray diffraction instrument that may provide broad X-ray diffraction peaks for SRO phases; e.g., broad peaks around 0.33 and 0.23 nm for allophane. Sample Analysis at Mars (SAM) heats samples and detects evolved gases of volatile-bearing phases including SRO phases (i.e., carbonates, sulfates, hydrated minerals). The Alpha Particle X-ray Spectrometer (APXS) and ChemCam element analyzers will provide chemical characterization of samples. The identification of SRO phases in surface materials on MSL will be challenging due to their nanocrystalline properties; their detection and identification will require utilizing the MSL instrument suite in concert. Ultimately, sample return missions will be required to definitively identify and fully characterize SRO minerals with state-of-the-art laboratory instrumentation back on Earth.

  15. Experimental Investigation and Simplistic Geochemical Modeling of CO2 Mineral Carbonation Using the Mount Tawai Peridotite

    OpenAIRE

    Omeid Rahmani; James Highfield; Radzuan Junin; Mark Tyrer; Amin Beiranvand Pour

    2016-01-01

    In this work, the potential of CO2 mineral carbonation of brucite (Mg(OH)2) derived from the Mount Tawai peridotite (forsterite based (Mg)2SiO4) to produce thermodynamically stable magnesium carbonate (MgCO3) was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor) were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The ...

  16. Effect of Additives and pH on the Formation of Carbonate Mineral by CO2 Sequestration of Cement Paste

    Science.gov (United States)

    Lee, J. H.; Hwang, J.; Lee, H.; Son, B. S.; Oh, J.

    2015-12-01

    CO2 in the atmosphere causes a global warming that is a big issue nowadays. Many studies of CO2 capture and storage (CCS) technologies have been studied all over the world. Waste cement is a good source for aqueous carbonation because it is rich in calcium. Therefore, this study was performed to develop the aqueous carbonation method for waste cement powder. Cement paste was made with water/cement ratio of 6:4 and cured for 28 days in water bath. The cement paste was pulverized into a fine powder sizing less than 0.15 mm. To study effect of additives and pH on the formation of carbonate minerals, aqueous carbonation experiments were conducted. The mineral compositions and morphology of carbonate mineral were identified by XRD and SEM/EDS analysis. 1.0 M NaCl and 0.25 M MgCl2 were applied as additives. Aqueous carbonation experiment was conducted with injecting pure CO2 gas (99.9%) to a reactor containing 200 ㎖ of reacting solution. The pH of reacting solution was controled to determine formational condition of carbonate minerals. In 0.25 M MgCl2 solution, calcite was dominant mineral at high pH. More aragonite, however, formed as decreasing pH of solution with injection of CO2. The presence of Mg2+ in solution makes aragonite more dominant than calcite. Aragonite was mainly formed at the high pH of solution with 1.0 M NaCl additive, whereas calcite was more preponderant mineral than aragonite as falling pH. It show that unstable aragonite transformed to calcite as decreasing pH. In no additive solution, vaterite was dominantly formed at the initial stage of experiement, but unstable vaterite transformed to well crystallized calcite with further carbonation.

  17. Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water

    International Nuclear Information System (INIS)

    Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. 14C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals’ surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly. - Graphical abstract: The stability of multi-walled carbon nanotubes in an aqueous system containing kaolinite, smectite or shale as model soil minerals is investigated using the 14C-labeling technique. Highlights: ► The interactions between MWCNTs and kaolinite, smectite, or shale were probed. ► Surface potential and hydrophobicity of the particles governs their interactions. ► EDLVO can be used to interpret the interactions. ► Insoluble organic materials in shale strongly sorb MWCNTs.

  18. Adsorption of EDTA on activated carbon from aqueous solutions

    International Nuclear Information System (INIS)

    In this study, the adsorption of EDTA on activated carbon from aqueous solutions has been investigated in a batch stirred cell. Experiments have been carried out to investigate the effects of temperature, EDTA concentration, pH, activated carbon mass and particle size on EDTA adsorption. The experimental results manifest that the EDTA adsorption rate increases with its concentration in the aqueous solutions. EDTA adsorption also increases with temperature. The EDTA removal from the solution increases as activated carbon mass increases. The Langmuir and Freundlich equilibrium isotherm models are found to provide a good fitting of the adsorption data, with R2 = 0.9920 and 0.9982, respectively. The kinetic study shows that EDTA adsorption on the activated carbon is in good compliance with the pseudo-second-order kinetic model. The thermodynamic parameters (Ea, ΔG0, ΔH0, ΔS0) obtained indicate the endothermic nature of EDTA adsorption on activated carbon.

  19. The Black Lake (Quebec, Canada) mineral carbonation experimental station: CO2 capture in mine waste

    Science.gov (United States)

    Beaudoin, G.; Constantin, M.; Duchesne, J.; Dupuis, C.; Entrazi, A.; Gras, A.; Huot, F.; Fortier, R.; Hebert, R.; Larachi, F.; Lechat, K.; Lemieux, J. M.; Molson, J. W. H.; Maldague, X.; Therrien, R.; Assima, G. P.

    2014-12-01

    Passive mineral carbonation of chrysotile mining and milling waste was discovered at the Black Lake mine, southern Québec, 10 years ago. Indurated crusts were found at the surface and within waste piles where mineral and rock fragments are cemented by hydrated magnesium carbonates. A long-term research program has yielded significant insight into the process of CO2 capture from the atmosphere, and how it can be implemented during mining operations. Laboratory experiments show that the waste mineralogy is crucial, brucite being more reactive than serpentine. Partial water saturation, circa 40%, is also critical to dissolve magnesium from minerals, and transport aqueous CO2 to precipitation sites. Grain armoring by iron oxidation induced by dissolved oxygen prevents further reaction. Two experimental cells constructed with milling waste and fitted with various monitoring probes (T, H2O content, leachate) and gas sampling ports, have been monitored for more than 3 years, along with environmental conditions. The interstitial gas in the cells remains depleted in CO2 indicating continuous capture of ambient atmospheric CO2 at rates faster than advection to reaction sites. The energy released by the exothermic mineral carbonation reactions has been observed both in laboratory experiments (up to 4 °C) and in the field. Warm air, depleted to 10 ppmv CO2, vents at the surface of the waste piles, indicating reaction with atmospheric CO2 deep inside the piles. A thermal anomaly, detected by airborne infrared and coincident with a known venting area, was selected for locating a 100 m deep borehole fitted with sensor arrays to monitor active mineral carbonation within the pile. The borehole has intersected areas where mineral carbonation has indurated the milling waste. The borehole will be monitored for the next 3 years to better understand the mineral carbonation process, and its potential to yield recoverable geothermal energy in mining environments.

  20. Interface Induced Carbonate Mineralization: A Fundamental Geochemical Process Relevant to Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Teng, H. Henry [PI, The George Washington University; Xu, Huifang [Co-PI, University of Wisconsin-Madison

    2013-07-17

    We have approached the long-standing geochemical question why anhydrous high-Mg carbonate minerals (i.e., magnesite and dolomite) cannot be formed at ambient conditions from a new perspective by exploring the formation of MgCO{sub 3} and Mg{sub x}Ca{sub (1-x)}CO{sub 3} in non-aqueous solutions. Data collected from our experiments in this funding period suggest that a fundamental barrier, other than cation hydration, exists that prevents Mg{sup 2+} and CO{sub 3}{sup 2-} ions from forming long-range ordered structures. We propose that this barrier mainly stems from the lattice limitation on the spatial configuration of CO{sub 3} groups in magnesite crystals. On the other hand, the measured higher distribution coefficients of Mg between magnesian calcites formed in the absence and presence of water give us a first direct proof to support and quantify the cation hydration effect.

  1. The efficiency of magnetic carbon activated by iron oxide nanoparticles in removing of Cu (II) from aqueous solutions

    OpenAIRE

    Salehe Salehnia; Behnam Barikbin; Hadighe Dorri

    2016-01-01

    Background and Aim: Copper ions, due to forming complexes with organic and mineral compounds, can have worrying effects on health and environment. In the present study, the effect of powdered magnetic carbon activated by iron-oxide nanoparticles in removing of CU (V; II) from aqueous solutions was assessed. Materials and Methods: This experimental study aimed at determining the effect of powdered magnetic carbon activated  by iron-oxide nanoparticles  parameters including PH, co...

  2. Mineral carbonation: energy costs of pretreatment options and insights gained from flow loop reaction studies

    International Nuclear Information System (INIS)

    Sequestration of carbon as a stable mineral carbonate has been proposed to mitigate environmental concerns that carbon dioxide may with time escape from its sequestered matrix using alternative sequestration technologies. A method has been developed to prepare stable carbonate products by reacting CO2 with magnesium silicate minerals in aqueous bicarbonate/chloride media at high temperature and pressure. Because this approach is inherently expensive due to slow reaction rates and high capital costs, studies were conducted to improve the reaction rates through mineral pretreatment steps and to cut expenses through improved reactor technology. An overview is given for the estimated cost of the process including sensitivity to grinding and heating as pretreatment options for several mineral feedstocks. The energy costs are evaluated for each pretreatment in terms of net carbon avoided. New studies with a high-temperature, high-pressure flow-loop reactor have yielded information on overcoming kinetic barriers experienced with processing in stirred autoclave reactors. Repeated tests with the flow-loop reactor have yielded insights on wear and failure of system components, on challenges to maintain and measure flow, and for better understanding of the reaction mechanism

  3. Carbonated aqueous media for quench heat treatment of steels

    Science.gov (United States)

    Nayak, U. Vignesh; Rao, K. M. Pranesh; Pai, M. Ashwin; Prabhu, K. Narayan

    2016-07-01

    Distilled water and polyalkylene glycol (PAG)-based aqueous quenchants of 5 and 10 vol.% with and without carbonation were prepared and used as heat transfer media during immersion quenching. Cooling curves were recorded during quenching of an inconel 600 cylindrical probe instrumented with multiple thermocouples. It was observed that the vapor stage duration was prolonged and the wetting front ascended uniformly for quenching with carbonated media. The cooling data were analyzed by determining the critical cooling parameters and by estimating the spatially dependent probe/quenchant interfacial heat flux transients. The study showed significantly reduced values of heat transfer rate for carbonated quenchants compared to quenchants without carbonation. Further, the reduction was more pronounced in the case of PAG-based carbonated quenchants than carbonated distilled water. The results also showed the dependence of heat transfer characteristics of the carbonated media on polymer concentration. The effect of quench uniformity on the microstructure of the material was assessed.

  4. Cesium removal from aqueous solution by natural mineral clinoptilolite

    Directory of Open Access Journals (Sweden)

    Nenadović Snežana S.

    2014-01-01

    Full Text Available The aim of this study was to investigate the Cs+ ions sorption on natural minerals clinoptilolite. The analysis of clinoptilolite and clinoptilolite with adsorbed Cs+ ion was con- ducted by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and gamma spectrometry. The specific activity of naturally occurring radionuclides in clinoptilolite was determined by gamma spectrometry by using the HPGe semiconductor detector. Obtained activity concentrations ranged from 49 Bq/kg to 810 Bq/kg for 40K, 5.7 Bq/kg to 10 Bq/kg for 238U, 5.8 Bq/kg to 70 Bq/kg for 232Th(228Ac, and the presence of artificial radionuclides was not detected (137Cs < 0.02 Bq/kg. The study of the thermal decomposition of raw clinoptilolite and Cs adsorbed clinoptilolite by differential thermal analysis is presented in this paper. The activation energy of the reaction phase transformation of raw clinoptilolite is 156.7 kJ/mol, while Cs adsorbed clinoptilolite is 121.7 kJ/mol. The lower value of activation energy reaction of the phase transformation Cs adsorbed clinoptilolite indicates that Cs which is adsorbed destabilizes the crystal structure of clinoptilolite and thus facilitates the transition to the amorphous state. [Projekat Ministarstva nauke Republike Srbije, br. 45012

  5. Solubility of carbon dioxide in aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W. J.; Dijkstra, H. B. S.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    In the present work, new experimental data are presented on the solubility of carbon dioxide in aqueous piperazine solutions, for concentrations of 0.2 and 0.6 molar piperazine and temperatures of 25, 40, and 70°C respectively. The present data, and other data available in the literature, were corr

  6. Minerals from Macedonia IV.Discrimination between some carbonate minerals by FTIR spectroscopy

    OpenAIRE

    Jovanovski, Gligor; Stefov, Viktor; Shoptrajanov, Bojan; Boev, Blazo

    2002-01-01

    The use of FTIR spectroscopy to distinguish between some geologically im­portant carbonate minerals (calcite - CaCO3), aragonite - CaCO3, siderite - FeCO3, magnesite - MgCO3, and dolomite - CaMg(CO3)2 originating from Macedonia and to detect mineral impurities in them is considered. 1t was shown that the series of the studied isomorphous calcite type minerals is an ideal test case for the evaluating the in­fluence of the corresponding cation upon the band frequencies or the carbonate ...

  7. Controls on carbon mineralization in ultramafic mine tailings

    Science.gov (United States)

    Harrison, A. L.; Power, I. M.; Dipple, G. M.; Mayer, K. U.; Wilson, S. A.

    2013-12-01

    Carbon mineralization in ultramafic mine tailings provides the opportunity to offset a significant portion of CO2 emissions from mining operations if passive mineralization rates are accelerated. To help design acceleration strategies, it is important to determine the controls on carbon mineralization in tailings, and to capture these effects using a reactive transport model to provide better estimation of the rates that could be achieved at different mine sites. For instance, it is likely that climatic variables influence rates of passive carbon mineralization. We use the reactive transport model MIN3P [1] to investigate the degree to which temperature, rainfall, and evaporation control passive carbon mineralization rates, as constrained with field observations from a mine site. Preliminary results suggest that hot and dry climates are most suitable. In addition, experimental evidence suggests that passive carbon mineralization is largely limited by the rate of CO2 supply into pore waters [2]. Acceleration could be achieved in part by supplying CO2-rich gas streams into tailings to carbonate highly reactive low abundance (< ~15 wt.%) phases such as brucite [Mg(OH)2] [3]. Column experiments containing brucite were supplied with 10 vol.% CO2 gas streams to assess the controls on carbon mineralization when the CO2 supply is increased. The influence of heterogeneous water content along the flow path and brucite grain size on carbon mineralization efficiency was investigated. Because water acts as both a reaction medium for CO2 and brucite dissolution and as a reactant to form hydrated carbonate minerals that sequester CO2, the extent of carbon mineralization was found to mimic the water content distribution. At low water content (<15% saturation), the extent of carbonation was extremely limited by the lack of available water. Variations in water content from the pore to the field scale therefore complicate the assessment of the carbon mineralization potential of a

  8. Tracing low-temperature aqueous metal migration in mineralized watersheds with Cu isotope fractionation

    International Nuclear Information System (INIS)

    Highlights: • Cu isotope fractionation of ores and waters identifies copper sulfide weathering. • Redox reactions cause isotopic shift measured in areas of sulfide weathering. • Consistent isotope signature in different deposit, climate, or concentration. - Abstract: Copper isotope signatures in waters emanating from mineralized watersheds provide evidence for the source aqueous copper in solution. Low-temperature aqueous oxidation of Cu sulfide minerals produces significant copper isotopic fractionation between solutions and residues. Abiotic experimental data of fractionation (defined as Δliquid–solid ‰ = δ65Culiquid − δ65Cusolid) are on the order of 1–3‰ and are unique for copper rich-sulfide minerals. Data presented here from ores and waters within defined boundaries of porphyry copper, massive sulfide, skarn, and epithermal ore deposits mimic abiotic experiments. Thus, the oxidation of sulfide minerals appears to cause the signatures in the waters although significant biological, temperature, and pH variations exist in the fluids. Regardless of the deposit type, water type, concentration of Cu in solution, or location, the data provide a means to trace sources of metals in solutions. This relationship allows for tracking sources and degree of metal migration in low temperature aqueous systems and has direct application to exploration geology and environmental geochemistry

  9. Stability of mineral matter in aqueous media of the Chernobyl Unit-4 Shelter: Thermodynamic evaluation

    International Nuclear Information System (INIS)

    A special geochemical environment exists within the Shelter (Sarcophagus) erected in 1986 over the destroyed Unit-4 of Chernobyl nuclear power plant (NPP). Based upon the available in situ and compositional data, thermodynamic models of solid-aqueous interactions were developed to clarify the leaching behavior of various materials within the Shelter. The Selektor-A code, based on a convex programming approach to Gibbs free energy minimization, was used for the calculations. A built-in flexible hybrid thermodynamic database for the system Na-K-Ca-Mg-Cl-S-N-H-O-Si-P-Fe-Al-Sr-Cs was extended with the critically selected and matched parameters for aqueous species and solid phases in the U-Zr-Si-O-H subsystem, secondary U-minerals, mineral phases of fully hydrated Portland cements and U-bearing zircons. Modeling results show that the Shelter Waters can selectively leach a significant quantity of U and Si from the fuel-containing masses, while Zr, Fe, Ca, Mg and some other components are rather insoluble. Serpentinite, assemblages of fully-hydrated phases of Portland cements, and oxidation products of steel structural elements are estimated to be sufficiently stable in the aqueous environment of the Shelter. Calculations also define some feasible pathways for secondary mineral formation from evaporation of Shelter water solutions and interactions between these waters with the mineral matter inside the Shelter

  10. Carbon Mineralization Using Phosphate and Silicate Ions

    Science.gov (United States)

    Gokturk, H.

    2013-12-01

    ions would enhance the absorption of CO2 into the aerosol even more than the singly or doubly charged ions. Ion containing aerosols also help to catalyze reactions between water and CO2. Hydrated phosphate and silicate ions tend to attract hydrogen atoms from neighboring water molecules to reduce the charged state. When there is CO2 in the vicinity of the ion, the remainder of the water molecule which loses the hydrogen(s) reacts with CO2 to form carbonates. (PO4---) + H2O + CO2 -> (HPO3--) + (HCO3-) (SiO4----) + H2O + CO2 -> (HSiO4---) + (HCO3-) (SiO4----) + H2O + CO2 -> (H2SiO4--) + (CO3--) In conclusion, highly charged phosphate and silicate ions dissolved in water and aerosolized into small droplets can facilitate both the capture and the mineralization of CO2. This method would be especially effective in a CO2 rich environment such as the exhaust gas of a combustion process. [1] H. Gokturk, "Geoengineering with Charged Droplets," AGU Fall Meeting, San Francisco 2011 [2] H. Gokturk, "Atomistic Simulation of Sea Spray Particles," AGU Fall Meeting, San Francisco 2012

  11. Methanogenesis-induced pH–Eh shifts drives aqueous metal(loid) mobility in sulfide mineral systems under CO2 enriched conditions

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Omar R.; Qafoku, Nikolla; Cantrell, Kirk J.; Wilkins, Michael J.; Brown, Christopher F.

    2016-01-15

    Accounting for microbially-mediated CO2 transformation is pivotal to assessing geochemical implications for elevated CO2 in subsurface environments. A series of batch-reactor experiments were conducted to decipher links between autotrophic methanogenesis, CO2 dynamics and aqueous Fe, As and Pb concentrations in the presence of sulfide minerals. Microbially-mediated solubility-trapping followed by pseudo-first order reduction of HCO3- to CH4 (k’ = 0.28-0.59 d-1) accounted for 95% of the CO2 loss from methanogenic experiments. Bicarbonate-to-methane reduction was pivotal in the mitigation of CO2-induced acidity (~1 pH unit) and enhancement of reducing conditions (Eh change from -0.215 to -0.332V ). Methanogenesis-associated shifts in pH-Eh values showed no significant effect on aqueous Pb but favored, 1) increased aqueous As as a result of microbially-mediated dissolution of arsenopyrite and 2) decreased aqueous Fe due to mineral-trapping of CO2-mobilized Fe as Fe-carbonate. Its order of occurrence (and magnitude), relative to solubility- and mineral-trapping, highlighted the potential for autotrophic methanogenesis to modulate both carbon sequestration and contaminant mobility in CO2-impacted subsurface environments.

  12. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail: cschi@kookmin.ac.kr

    2006-09-25

    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  13. Kinetics of Aqueous Leaching and Carbonization of Steelmaking Slag

    Science.gov (United States)

    Lekakh, S. N.; Rawlins, C. H.; Robertson, D. G. C.; Richards, V. L.; Peaslee, K. D.

    2008-02-01

    Sequestration of carbon dioxide by steelmaking slag was studied in an atmospheric three-phase system containing industrial slag particles, water, and CO2 gas. Batch-type reactors were used to measure the rate of aqueous alkaline leaching and slag particle carbonization independently. Four sizes of slag particles were tested for the Ca leaching rate in deionized water at a constant 7.5 pH in an argon atmosphere and for carbonate conversion with CO2 bubbled through an aqueous suspension. Conversion data (fraction of Ca leached or converted to carbonate) were evaluated to determine the rate-limiting step based on the shrinking core model. For Ca leaching, the chemical reaction is the controlling mechanism during the initial period of time, which then switches to diffusion through the developed porous layer as the rate-limiting step. Carbonate conversion proceeded much slower than leaching conversion and was found to be limited by diffusion through the product calcium carbonate layer. The calculated value of diffusivity was found to be 5 × 10-9 cm2/s, which decreased by an order of magnitude with increasing carbonization conversion as a result of changing density of the product layer. The experimental data fit the shrinking core model well after correction for the particle specific surface area.

  14. Spectroscopic Identification of Carbonate Minerals in the Martian Dust

    Science.gov (United States)

    Bandfield, Joshua L.; Glotch, Timothy D.; Christensen, Philip R.

    2003-08-01

    Thermal infrared spectra of the martian surface indicate the presence of small concentrations (~2 to 5 weight %) of carbonates, specifically dominated by magnesite (MgCO3). The carbonates are widely distributed in the martian dust, and there is no indication of a concentrated source. The presence of small concentrations of carbonate minerals in the surface dust and in martian meteorites can sequester several bars of atmospheric carbon dioxide and may have been an important sink for a thicker carbon dioxide atmosphere in the martian past.

  15. Sorption of a mixture of phenols in aqueous solution with activated carbon

    International Nuclear Information System (INIS)

    The main objective of this work is the sorption of an aqueous mixture of phenol-4 chloro phenol of different concentrations in a molar relationship 1:1 in activated carbon of mineral origin of different nets (10, 20 and 30) and to diminish with it its presence in water. The experimental results show that the removal capacity depends so much of the surface properties of the sorbent like of the physical and chemical properties of the sorbate. In all the cases it was observed that in the aqueous systems of low concentration the 4-chloro phenol are removed in an approximate proportion of 1.2-4 times greater to than phenol, however to concentrations but high both they are removed approximately in the same proportion. (Author)

  16. The utilisation of fly ash in CO2 mineral carbonation

    Directory of Open Access Journals (Sweden)

    Jaschik Jolanta

    2016-03-01

    Full Text Available The fixation of CO2 in the form of inorganic carbonates, also known as mineral carbonation, is an interesting option for the removal of carbon dioxide from various gas streams. The captured CO2 is reacted with metal-oxide bearing materials, usually naturally occurring minerals. The alkaline industrial waste, such as fly ash can also be considered as a source of calcium or magnesium. In the present study the solubility of fly ash from conventional pulverised hard coal fired boilers, with and without desulphurisation products, and fly ash from lignite fluidised bed combustion, generated by Polish power stations was analysed. The principal objective was to assess the potential of fly ash used as a reactant in the process of mineral carbonation. Experiments were done in a 1 dm3 reactor equipped with a heating jacket and a stirrer. The rate of dissolution in water and in acid solutions was measured at various temperatures (20 - 80ºC, waste-to-solvent ratios (1:100 - 1:4 and stirrer speeds (300 - 1100 min-1. Results clearly show that fluidised lignite fly ash has the highest potential for carbonation due to its high content of free CaO and fast kinetics of dissolution, and can be employed in mineral carbonation of CO2.

  17. Aqueous dissolution, solubilities and thermodynamic stabilities of common aluminosilicate clay minerals: Kaolinite and smectites

    Science.gov (United States)

    May, Howard M.; Klnniburgh, D.G.; Helmke, P.A.; Jackson, M.L.

    1986-01-01

    Determinations of the aqueous solubilities of kaolinite at pH 4, and of five smectite minerals in suspensions set between pH 5 and 8, were undertaken with mineral suspensions adjusted to approach equilibrium from over- and undersaturation. After 1,237 days, Dry Branch, Georgia kaolinite suspensions attained equilibrium solubility with respect to the kaolinite, for which Keq = (2.72 ?? 0.35) ?? 107. The experimentally determined Gibbs free energy of formation (??Gf,2980) for the kaolinite is -3,789.51 ?? 6.60 kj mol-1. Equilibrium solubilities could not be determined for the smectites because the composition of the solution phase in the smectite suspensions appeared to be controlled by the formation of gibbsite or amorphous aluminum hydroxide and not by the smectites, preventing attempts to determine valid ??Gf0 values for these complex aluminosilicate clay minerals. Reported solubility-based ??Gf0 determinations for smectites and other variable composition aluminosilicate clay minerals are shown to be invalid because of experimental deficiencies and of conceptual flaws arising from the nature of the minerals themselves. Because of the variable composition of smectites and similar minerals, it is concluded that reliable equilibrium solubilities and solubility-derived ??Gf0 values can neither be rigorously determined by conventional experimental procedures, nor applied in equilibriabased models of smectite-water interactions. ?? 1986.

  18. Bioleaching of serpentine group mineral by fungus Talaromyces flavus: application for mineral carbonation

    Science.gov (United States)

    Li, Z.; Lianwen, L.; Zhao, L.; Teng, H.

    2011-12-01

    Many studies of serpentine group mineral dissolution for mineral carbonation have been published in recent years. However, most of them focus mainly on either physical and chemical processes or on bacterial function, rather than fungal involvement in the bioleaching of serpentine group mineral. Due to the excessive costs of the magnesium dissolution process, finding a lower energy consumption method will be meaningful. A fungal strain Talaromyces flavus was isolated from serpentinic rock of Donghai (China). No study of its bioleaching ability is currently available. It is thus of great significance to explore the impact of T. flavus on the dissolution of serpentine group mineral. Serpentine rock-inhabiting fungi belonging to Acremonium, Alternaria, Aspergillus, Botryotinia, Cladosporium, Clavicipitaceae, Cosmospora, Fusarium, Monascus, Paecilomyces, Penicillium, Talaromyces, Trichoderma were isolated. These strains were chosen on the basis of resistance to magnesium and nickel characterized in terms of minimum inhibiting concentration (MIC). Specifically, the strain Talaromyces flavus has a high tolerance to both magnesium (1 mol/L) and nickel (10 mM/L), and we examine its bioleaching ability on serpentine group mineral. Contact and separation experiments (cut-off 8 000-14 000 Da), as well as three control experiments, were set up for 30 days. At least three repeated tests were performed for each individual experiment. The results of our experiments demonstrate that the bioleaching ability of T. flavus towards serpentine group mineral is evident. 39.39 wt% of magnesium was extracted from lizardite during the bioleaching period in the contact experiment, which showed a dissolution rate at about a constant 0.126 mM/d before reaching equilibrium in 13 days. The amount of solubilized Mg from chrysotile and antigorite were respectively 37.79 wt% and 29.78 wt% in the contact experiment. These results make clear the influence of mineral structure on mineral bioleaching

  19. Accelerated mineral carbonation of stainless steel slags for CO2 storage and waste valorization: effect of process parameters on geochemical properties

    OpenAIRE

    Santos, Rafael; Van Bouwel, Jens; Vandevelde, Ellen; Mertens, Gilles; Elsen, Jan; Van Gerven, Tom

    2013-01-01

    This work explores the mineral carbonation of stainless steel slags in search for a technically and economically feasible treatment solution that steers these waste residues away from costly disposal in landfills and into valuable applications. Argon Oxygen Decarburization (AOD) and Continuous Casting (CC) slags prove ideal for mineral carbonation as their powdery morphology forgoes the need for milling and provides sufficient surface area for high reactivity towards direct aqueous carbonatio...

  20. Simultaneous leaching and carbon sequestration in constrained aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, Tommy Joe [ORNL; Moon, Ji Won [ORNL; Roh, Yul [Chonnam National University, Gwangju; Cho, Kyu Seong [ORNL

    2011-01-01

    The behavior of metal ions leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO(2)/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO(2) capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals.

  1. Mineral sequestration of carbon dioxide in San Carlos olivine: An atomic level reaction study

    Science.gov (United States)

    Nunez, Ryan

    Since the late 19th century, atmospheric carbon dioxide (CO2) levels have been steadily on the rise. Approximately one third of all human emissions come from fossil fuel power plants. As countries become more dependent on electrical energy and bring on line new power plants, these atmospheric CO2 levels will continue to rise, generating strong environmental concern. Potential avenues to address this problem convert the CO2 from the gaseous phase to a liquid, supercritical fluid, or solid state and store it. Oceans, subsurface reservoirs such as depleted oil fields, and terrestrial carbon pools have all been suggested. The essential problem with all of these possible solutions is the issue of permanency. Mineral sequestration of CO2 is a candidate technology for reducing the amount of anthropogenic CO2 that is being released into the atmosphere. Olivine (e.g. forsterite, Mg2SiO4) is a widely available mineral that reacts with CO2 to form magnesite (MgCO3) and silica (SiO2). Magnesite is capable of immobilizing CO2 over geological time periods. Thus the issue of permanency has been addressed. The most promising mineral sequestration process developed to date is aqueous solution mineral carbonation. The solid/aqueous solution reaction interface provides insight to the mechanisms that govern the carbonation reactivity of olivine. Study of these mechanisms at the atomic level is critically important to facilitate engineering new processes that will enhance the reactivity of olivine with CO2 bearing media and to lower process costs. The study of the olivine carbonation reaction herein can be divided into three separate areas of research. The first area is a comprehensive study of olivine under conditions of electron irradiation. Analyzing radiation damage is critical to the verification and reliability of data collected from the samples using electron beam techniques. The next area of research is the analysis of the reaction layer composition and structure using High

  2. Experimental Investigation and Simplistic Geochemical Modeling of CO₂ Mineral Carbonation Using the Mount Tawai Peridotite.

    Science.gov (United States)

    Rahmani, Omeid; Highfield, James; Junin, Radzuan; Tyrer, Mark; Pour, Amin Beiranvand

    2016-01-01

    In this work, the potential of CO₂ mineral carbonation of brucite (Mg(OH)2) derived from the Mount Tawai peridotite (forsterite based (Mg)₂SiO4) to produce thermodynamically stable magnesium carbonate (MgCO3) was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor) were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO₃ is ~99%, which occurred at temperatures between 150 and 175 °C. It was also found that the reduction of particle size range from >200 to <75 µm enhanced the leaching rate significantly. In addition, the results showed the essential role of water vapor in promoting effective carbonation. By increasing water vapor concentration from 5 to 10 vol %, the mineral carbonation rate increased by 30%. This work has also numerically modeled the process by which CO₂ gas may be sequestered, by reaction with forsterite in the presence of moisture. In both experimental analysis and geochemical modeling, the results showed that the reaction is favored and of high yield; going almost to completion (within about one year) with the bulk of the carbon partitioning into magnesite and that very little remains in solution. PMID:26999082

  3. Experimental Investigation and Simplistic Geochemical Modeling of CO2 Mineral Carbonation Using the Mount Tawai Peridotite

    Directory of Open Access Journals (Sweden)

    Omeid Rahmani

    2016-03-01

    Full Text Available In this work, the potential of CO2 mineral carbonation of brucite (Mg(OH2 derived from the Mount Tawai peridotite (forsterite based (Mg2SiO4 to produce thermodynamically stable magnesium carbonate (MgCO3 was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO3 is ~99%, which occurred at temperatures between 150 and 175 °C. It was also found that the reduction of particle size range from >200 to <75 µm enhanced the leaching rate significantly. In addition, the results showed the essential role of water vapor in promoting effective carbonation. By increasing water vapor concentration from 5 to 10 vol %, the mineral carbonation rate increased by 30%. This work has also numerically modeled the process by which CO2 gas may be sequestered, by reaction with forsterite in the presence of moisture. In both experimental analysis and geochemical modeling, the results showed that the reaction is favored and of high yield; going almost to completion (within about one year with the bulk of the carbon partitioning into magnesite and that very little remains in solution.

  4. Review of Distribution Coefficients for Radionuclides in Carbonate Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M

    2009-08-14

    An understanding of the transport of radionuclides in carbonate minerals is necessary to be able to predict the fate of (and potentially remediate) radionuclides in the environment. In some environments, carbonate minerals such as calciate, aragonite, dolomite and limestone are present and an understanding of the sorption of radionuclides in these carbonate minerals is therefore advantageous. A list of the radionuclides of interest is given in Table 1. The distribution coefficient, K{sub d} is defined as the ratio of the contaminant concentration bound on the solid phase to the contaminant concentration remaining in the liquid phase at equilibrium. Some authors report distribution coefficients and other report partition coefficients, the data presented in this work assumes equality between these two terms, and data are presented and summarized in this work as logarithmic distribution coefficient (log K{sub D}). Published literature was searched using two methods. Firstly, the JNC Sorption Database, namely Shubutani et al (1999), and Suyama and Sasamoto (2004) was used to select elements of interest and a number of carbonate minerals. Secondly, on-line literature search tools were used to locate relevant published articles from 1900 to 2009. Over 300 data points covering 16 elements (hydrogen, carbon, calcium, nickel, strontium, technetium, palladium, iodine, cesium, samarium, europium, holmium, uranium, neptunium, plutonium and americium) were used to calculate an average and range of log K{sub d} values for each element. Unfortunately, no data could be found for chlorine, argon, krypton, zirconium, niobium, tin, thorium and curium. A description of the data is given below, together with the average, standard deviation, minimum, maximum and number of inputs for radionuclide K{sub d} values for calcite, aragonate, limestone, dolomite and unidentified carbonate rocks in Table 2. Finally, the data are condensed into one group (carbonate minerals) of data for each

  5. Review of Distribution Coefficients for Radionuclides in Carbonate Minerals

    International Nuclear Information System (INIS)

    An understanding of the transport of radionuclides in carbonate minerals is necessary to be able to predict the fate of (and potentially remediate) radionuclides in the environment. In some environments, carbonate minerals such as calciate, aragonite, dolomite and limestone are present and an understanding of the sorption of radionuclides in these carbonate minerals is therefore advantageous. A list of the radionuclides of interest is given in Table 1. The distribution coefficient, Kd is defined as the ratio of the contaminant concentration bound on the solid phase to the contaminant concentration remaining in the liquid phase at equilibrium. Some authors report distribution coefficients and other report partition coefficients, the data presented in this work assumes equality between these two terms, and data are presented and summarized in this work as logarithmic distribution coefficient (log KD). Published literature was searched using two methods. Firstly, the JNC Sorption Database, namely Shubutani et al (1999), and Suyama and Sasamoto (2004) was used to select elements of interest and a number of carbonate minerals. Secondly, on-line literature search tools were used to locate relevant published articles from 1900 to 2009. Over 300 data points covering 16 elements (hydrogen, carbon, calcium, nickel, strontium, technetium, palladium, iodine, cesium, samarium, europium, holmium, uranium, neptunium, plutonium and americium) were used to calculate an average and range of log Kd values for each element. Unfortunately, no data could be found for chlorine, argon, krypton, zirconium, niobium, tin, thorium and curium. A description of the data is given below, together with the average, standard deviation, minimum, maximum and number of inputs for radionuclide Kd values for calcite, aragonate, limestone, dolomite and unidentified carbonate rocks in Table 2. Finally, the data are condensed into one group (carbonate minerals) of data for each element of interest in Table

  6. Black Carbon, The Pyrogenic Clay Mineral?

    Science.gov (United States)

    Most soils contain significant amounts of black carbon, much of which is present as discrete particles admixed with the coarse clay fraction (0.2–2.0 µm e.s.d.) and can be physically separated from the more abundant diffuse biogenic humic materials. Recent evidence has shown that naturally occurring...

  7. Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions

    Science.gov (United States)

    Matter, Juerg M.; Stute, Martin; Snæbjörnsdottir, Sandra Ó.; Oelkers, Eric H.; Gislason, Sigurdur R.; Aradottir, Edda S.; Sigfusson, Bergur; Gunnarsson, Ingvi; Sigurdardottir, Holmfridur; Gunnlaugsson, Einar; Axelsson, Gudni; Alfredsson, Helgi A.; Wolff-Boenisch, Domenik; Mesfin, Kiflom; Taya, Diana Fernandez de la Reguera; Hall, Jennifer; Dideriksen, Knud; Broecker, Wallace S.

    2016-06-01

    Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2. This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. We find that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years. This result contrasts with the common view that the immobilization of CO2 as carbonate minerals within geologic reservoirs takes several hundreds to thousands of years. Our results, therefore, demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated.

  8. Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions.

    Science.gov (United States)

    Matter, Juerg M; Stute, Martin; Snæbjörnsdottir, Sandra Ó; Oelkers, Eric H; Gislason, Sigurdur R; Aradottir, Edda S; Sigfusson, Bergur; Gunnarsson, Ingvi; Sigurdardottir, Holmfridur; Gunnlaugsson, Einar; Axelsson, Gudni; Alfredsson, Helgi A; Wolff-Boenisch, Domenik; Mesfin, Kiflom; Taya, Diana Fernandez de la Reguera; Hall, Jennifer; Dideriksen, Knud; Broecker, Wallace S

    2016-06-10

    Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2 This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. We find that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years. This result contrasts with the common view that the immobilization of CO2 as carbonate minerals within geologic reservoirs takes several hundreds to thousands of years. Our results, therefore, demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated. PMID:27284192

  9. Enhancement of Mineral Carbonation of Various Ultramafic Mine Tailings

    Science.gov (United States)

    Tremblay, J.; Duchesne, J.; Beaudoin, G.; Constantin, M.; Hébert, R.; Larachi, F.; Lemieux, J.; Molson, J. W.

    2011-12-01

    Capture of atmospheric CO2 in minerals to form magnesium and/or calcium carbonates is a process for permanent sequestration of CO2. Mineral carbonation occurs naturally in some ultramafic mining waste forming cemented crusts at surface, whereas reaction within the waste piles vents CO2-depleted air at the top of the piles. The purpose of this research is to kinetically enhance the mineral carbonation of different ultramafic mine tailings by addition of neutral organic salts and pH adjustments in order to reach a compromise between solubility of magnesium ions and carbonate precipitation. Real time monitoring of CO2 uptake at atmospheric conditions was performed using the Laval eudiometers, which allows calculation of the rate of the mineral carbonation reaction. Tests were conducted by varying the concentration of CO2 in the gas phase, the tailing water content and the material porosity to determine the optimal carbonation conditions. Subsequently, carbonation tests with different pH and various concentrations of organic salts (or chelate) such as sodium EDTA, sodium oxalate and sodium citrate were evaluated. Preliminary results indicate that CO2 reacts with the total mass of the sample and not only with the layer in contact with the gas phase. The water content for optimal carbonation reaction ranged from 20% and 60% according to the type of tailing investigated. Interstitial water is necessary as solvent for dissolution of Mg ions, but saturated pores reduce diffusion of CO2. A linear relationship was obtained between the CO2 concentration in the gas mixture and the CO2 absorption rate of the mine tailings. Increase of tailings porosity by addition of inert aluminum oxide enhances the carbonation reaction probably by facilitating CO2 diffusion in increased pore space. CO2 uptake was increased by 60% over distilled water, using a saturated solution of sodium citrate (1.5 M) and NaHCO3, by 14 to 19% using a saturated solution of sodium EDTA (0.2 M) and NaHCO3 and

  10. Co-mineralization of alkaline-earth carbonates and silica

    OpenAIRE

    Kellermeier, Matthias

    2011-01-01

    This thesis is concerned with the manifold interactions that occur when alkaline-earth metal carbonates are crystallized in the presence of dissolved silica as an additive. The described work subdivides into two main lines of research. On the one hand, an understanding of the potential roles of silica during crystallization was sought on a fundamental level. That is, the mineral - in this case calcium carbonate - was directly precipitated from silica-containing solutions and the effect on gro...

  11. Dynamic response of porous calcium carbonate minerals

    International Nuclear Information System (INIS)

    A theoretical study of the shock-loaded response of calcium carbonate materials is presented in which both dry and water-saturated samples with porosities up to 50 percent are considered. Data are presented for the unloading response from 15.0 and 18.5 GPa, and calculations from a mixture model using a Mie-Grueneisen equation of state with volume-dependent parameters are compared to both the Hugoniot and the isentropic unloading response

  12. Kinetics of carbonate dissolution in CO2-saturated aqueous system at reservoir conditions

    Science.gov (United States)

    Peng, Cheng; Crawshaw, John P.; Maitland, Geoffrey; Trusler, J. P. Martin

    2014-05-01

    In recent years, carbon capture and storage (CCS) has emerged as a key technology for limiting anthropogenic CO2 emissions while allowing the continued utilisation of fossil fuels. The most promising geological storage sites are deep saline aquifers because the capacity, integrity and injection economics are most favourable, and the environmental impact can be minimal. Many rock-fluid chemical reactions are known to occur both during and after CO2 injection in saline aquifers. The importance of rock-fluid reactions in the (CO2 + H2O) system can be understood in terms of their impact on the integrity and stability of both the formation rocks and cap rocks. The chemical interactions between CO2-acidified brines and the reservoir minerals can influence the porosity and permeability of the formations, resulting in changes in the transport processes occurring during CO2 storage. Since carbonate minerals are abundant in sedimentary rocks, one of the requirements to safely implement CO2 storage in saline aquifers is to characterise the reactivity of carbonate minerals in aqueous solutions at reservoir conditions. In this work, we reported measurements of the intrinsic rate of carbonate dissolution in CO2-saturated water under high-temperature high-pressure reservoir conditions extending up to 373 K and 14 MPa. The rate of carbonate dissolution in CO2-free HCl(aq) was also measured at ambient pressure at temperatures up to 353 K. Various pure minerals and reservoir rocks were investigated in this study, including single-crystals of calcite and magnesite, and samples of dolomite, chalks and sandstones. A specially-designed batch reactor system, implementing the rotating disc technique, was used to obtain the intrinsic reaction rate at the solid/liquid interface, free of mass transfer effects. The effective area and mineralogy of the exposed surface was determined by a combination of surface characterisation techniques including XRD, SEM, EDX and optical microscopy. The

  13. Treated Carbon Nanofibers for Storing Energy in Aqueous KOH

    Science.gov (United States)

    Firsich, David W.

    2004-01-01

    A surface treatment has been found to enhance the performances of carbon nanofibers as electrode materials for electrochemical capacitors in which aqueous solutions of potassium hydroxide are used as the electrolytes. In the treatment, sulfonic acid groups are attached to edge plane sites on carbon atoms. The treatment is applicable to a variety of carbon nanofibers, including fibrils and both single- and multiple-wall nanotubes. The reason for choosing nanofibers over powders and other forms of carbon is that nanofibers offer greater power features. In previous research, it was found that the surface treatment of carbon nanofibers increased energy-storage densities in the presence of acid electrolytes. Now, it has been found that the same treatment increases energy-storage densities of carbon nanofibers in the presence of alkaline electrolytes when the carbon is paired with a NiOOH electrode. This beneficial effect varies depending on the variety of carbon substrate to which it is applied. It has been conjectured that the sulfonic acid groups, which exist in a deprotonated state in aqueous KOH solutions, undergo reversible electro-chemical reactions that are responsible for the observed increases in energystorage capacities. The increases can be considerable: For example, in one case, nanofibers exhibited a specific capacitance of 34 Farads per gram before treatment and 172 Farads per gram (an increase of about 400 percent) after treatment. The most promising application of this development appears to lie in hybrid capacitors, which are devices designed primarily for storing energy. These devices are designed to be capable of (1) discharge at rates greater than those of batteries and (2) storing energy at densities approaching those of batteries. A hybrid capacitor includes one electrode like that of a battery and one electrode like that of an electrochemical capacitor. For example, a hybrid capacitor could contain a potassium hydroxide solution as the electrolyte

  14. A Numerical Study on Combining CO2 Mineral Carbonation and Geothermal Energy Development

    Science.gov (United States)

    Wan, Y.; Xu, T.; Pruess, K.

    2010-12-01

    There is growing interest in the novel concept of operating Enhanced Geothermal Systems (EGS) with CO2 instead of water as heat transmission fluid. Initial studies have suggested that CO2 may achieve larger rates of heat extraction, and can offer geologic storage of carbon as an ancillary benefit. A fully developed EGS with CO2 would consist of three distinct zones, (1) a central zone or “core” in which all aqueous phase has been removed by dissolution into the flowing CO2 stream, so that the reservoir fluid is a single supercritical CO2 phase; (2) a surrounding intermediate zone, in which the reservoir fluid consists of a two-phase water-CO2 mixture; and (3) an outer or peripheral zone, in which the reservoir fluid is a single aqueous phase with dissolved CO2. Fluid-rock interactions in EGS operated with CO2 are expected to be vastly different in zones with an aqueous phase present, as compared to the central reservoir zone with anhydrous supercritical CO2. We have performed chemically reactive transport (TOUGHREACT ) modeling to investigate fluid-rock interactions and CO2 mineral carbonation of an EGS operated with CO2. The quartz monzodiorite unit at the Enhanced Geothermal Systems (EGS) site at Desert Peak (Nevada) was taken as an example. A geothermal injection well system with supercritical CO2 injection was simulated to (1) investigate mineral dissolution/precipitation and associated porosity changes, and (2) impacts on reservoir growth and longevity, with ramifications for sustaining energy recovery, for estimating CO2 loss rates, and for figuring tradeoffs between power generation and CO2 mineralization (geologic storage).

  15. Application of Ozone Related Processes to Mineralize Tetramethyl Ammonium Hydroxide in Aqueous Solution

    OpenAIRE

    Chyow-San Chiou; Kai-Jen Chuang; Ya-Fen Lin; Hua-Wei Chen; Chih-Ming Ma

    2013-01-01

    Tetramethyl ammonium hydroxide (TMAH) is an anisotropic etchant used in the wet etching process of the semiconductor industry and is hard to degrade by biotreatments when it exists in wastewater. This study evaluated the performance of a system combined with ultraviolet, magnetic catalyst (SiO2/Fe3O4) and O3, denoted as UV/O3, to TMAH in an aqueous solution. The mineralization efficiency of TMAH under various conditions follows the sequence: UV/O3 > UV/H2O2/O3 > H2O2/SiO2/Fe3O4/O3 > H2O2/O3 >...

  16. Direct Use of Mineral Carbonate for Autotrophy Among Euendolithic Cyanobacteria

    Science.gov (United States)

    Guida, B. S.

    2015-12-01

    Cyanobacteria are oxygenic photoautotrophs, and arguably the most important primary producers on the planet, fixing carbon from dissolved inorganic carbon (DIC) in the aquatic environment, and directly from atmospheric CO2 in terrestrial systems. Euendolithic cyanobacteria occupy a very specific niche, inside rocks, which can potentially preclude them from easily accessing those carbon pools, and yet, natural euendolithic communities can support food webs in habitats where they are prominent, such as in marine carbonate platforms and desert carbonate outcrops. In a recently proposed model describing the mechanism of cyanobacterial carbonate boring, we postulated that as the organism dissolves the mineral, liberated CO32- anions will be quickly converted to HCO3- and assimilated directly, making the cyanobacterium independent of external DIC pools for autotrophy. We used natural abundance and tracer stable carbon (13C) isotope analyses accompanied by nanoSIMS imaging in model laboratory systems of cultivated cyanobacteria and in natural mixed communities of marine euendoliths to study the ultimate source of carbon in their biomass. Our results clearly demonstrate that endolithic biomass of these cyanobacteria is significantly derived from mineral carbonate, as opposed to free-living or epilithic biomass, where the source is mixed or coming from the dissolved pool, this holds for model cultures as well as natural communities. In fact, we can increase the lifestyle preference of cultures for endolithic growth versus planktonic or benthic growth, by simply imposing an external DIC limitation in the presence of a carbonate substrate. Our results predict that benthic communities (extant or fossil) that rely heavily on primary production by euendolithic primary producers may show 13C signatures that mimic those of the surrounding carbonate substrate rather than from those of the local seawater.

  17. THERAPEUTIC EFFECTS OF CARBONATED MINERAL WATERS IN CARDIOVASCULAR REHABILITATION

    Directory of Open Access Journals (Sweden)

    Dogaru Gabriela

    2015-02-01

    Full Text Available Carbonated water baths represent a method used for the prevention and treatment of cardiovascular diseases in some spa resorts in Romania. Carbonated mineral waters are the result of the filtration of depth waters through volcanic soils that contain carbon dioxide. The most important effect is the direct effect of carbon dioxide, which is absorbed through the skin, with an absorption coefficient of 30-35 ml/min/sqm body surface area. An excitation of vascular receptors and a dilation of dermal papillae, responsible for skin erythema, occur. The effects of the carbonated water bath on the cardiovascular system are the following: decrease of peripheral resistance by the direct action of carbon dioxide on arterioles and arteriovenous anastomoses; increase of both systolic and diastolic cardiac output, not by central mechanism as in the case of hot baths, but initially, by passive peripheral vasodilation, without increased venous return; subsequently, by accumulation in the cutaneous venous system, venous return towards the right heart will be increased, with a higher diastolic filling and a higher stroke volume. Carbonated water baths increase arteriolar blood flow in the skin, the vasodilator effect being directly proportional to the carbon dioxide concentration in the mineral bath. The effect of external carbonated water treatment is based on mechanical and thermal action, as well as on the chemical properties of carbon dioxide, its influence being either local or postabsorptive. Carbonated water baths are a therapeutic method that is also used in the treatment facilities of the Baile Tusnad spa resort, under the supervision of qualified medical experts, in a pleasant environment close to nature.

  18. Complete mineralization of perfluorooctanoic acid (PFOA) by γ-irradiation in aqueous solution

    Science.gov (United States)

    Zhang, Ze; Chen, Jie-Jie; Lyu, Xian-Jin; Yin, Hao; Sheng, Guo-Ping

    2014-12-01

    Decomposition of perfluorooctanoic acid (C7F15COOH, PFOA) has been gaining increasing interests because it is a ubiquitous environmental contaminant and resistant to the most conventional treatment processes. In this work, the rapid and complete mineralization of PFOA and simultaneous defluorination were achieved by γ-ray irradiation with a 60Co source. The degradation rate of PFOA by γ-ray irradiation would be high, and a pseudo-first-order kinetic rate constant of 0.67 h-1 could be achieved in the N2 satured condition at pH 13.0. The experimental results and quantum chemical calculation confirmed that two radicals, i.e., hydroxyl radical (.OH) and aqueous electrons (eaq-), were responsible for the degradation of PFOA, while only either eaq- or .OH might not be able to accomplish complete mineralization of PFOA. The synergistic effects of .OH and eaq- involved in the cleavage of C-C and C-F bonds, and therefore complete mineralization of PFOA were achieved. The intermediate products were identified and the degradation pathway was also proposed. The results of this study may offer a useful, high-efficient approach for complete mineralizing fluorochemicals and other persistent pollutants.

  19. In situ analysis of aqueous structure and adsorption at fluorocarbon, hydrocarbon and mineral surfaces

    Science.gov (United States)

    Hopkins, Adam Justin

    Altering and controlling the properties of solid surfaces in aqueous or other liquid phase environments has been a sought after objective for decades. With the discovery of chemisorbed self-assembled monolayers, this dream has become a reality. Oxide and metal surfaces can now be readily coated with an array of commercially available products to produce a desired fnctionality. The presence of these coatings on solid surfaces affects properties of the interfacial region by altering interfacial electrostatic fields, changing the structure of interfacial water molecules and altering the interactions of adsorbed species. This dissertation reports on in situ studies of adsorption at several solid/aqueous interfaces using vibrational sum-frequency spectroscopy, a surface specific technique. These studies are augmented by the use of atomic force microscopy and contact angle goniometry to characterize the prepared surfaces and their interactions with adsorbates. The studies investigate how changes in the surface structure and chemistry, as well as the bulk aqueous phase, affect interfacial structure. The studies within are primarily focused on the interactions of water with bare and functionalized fused silica and the relationship between the aqueous phase composition and the structure of fluorocarbon and hydrocarbon self-assembled monolayers. The variations in aqueous structure are then examined in detail using ionic strength controlled experiments to understand the direct interactions of water hydrophobically coated silica. This analysis is followed by an investigation of the competitive adsorption of methanol and water at fluorocarbon and hydrocarbon monolayers which show spectroscopic signatures of the interaction strength between fluorocarbons and hydrocarbons. Further studies are performed using butylammonium chloride to verify these spectroscopic signatures and reveal different molecular structures of adsorbed species at chemically different hydrophobic surfaces

  20. Electrosorption of inorganic salts from aqueous solution using carbon aerogels.

    Science.gov (United States)

    Gabelich, Christopher J; Tran, Tri D; Suffet, I H Mel

    2002-07-01

    Capacitive deionization (CDI) with carbon aerogels has been shown to remove various inorganic species from aqueous solutions, though no studies have shown the electrosorption behavior of multisolute systems in which ions compete for limited surface area. Several experiments were conducted to determine the ion removal capacity and selectivity of carbon aerogel electrodes, using both laboratory and natural waters. Although carbon aerogel electrodes have been treated as electrical double-layer capacitors, this study showed that ion sorption followed a Langmuir isotherm, indicating monolayer adsorption. The sorption capacity of carbon aerogel electrodes was approximately 1.0-2.0 x 10(-4) equiv/g aerogel, with ion selectivity being based on ionic hydrated radius. Monovalent ions (e.g., sodium) with smaller hydrated radii were preferentially removed from solution over multivalent ions (e.g., calcium) on a percent or molar basis. Because of the relatively small average pore size (4-9 nm) of the carbon aerogel material, only 14-42 m2/g aerogel surface area was available for ion sorption. Natural organic matter may foul the aerogel surface and limit CDI effectiveness in treating natural waters. PMID:12144279

  1. Electrochemical Properties of Nanoporous Carbon Material in Aqueous Electrolytes.

    Science.gov (United States)

    Rachiy, Bogdan I; Budzulyak, Ivan M; Vashchynsky, Vitalii M; Ivanichok, Nataliia Ya; Nykoliuk, Marian O

    2016-12-01

    The paper is devoted to the study of the behavior of capacitor type electrochemical system in the К(+)-containing aqueous electrolytes. Nanoporous carbon material (NCM) was used as the electrode material, obtained by carbonization of plant raw materials with the following chemical activation. Optimization of pore size distribution was carried out by chemical-thermal method using potassium hydroxide as activator. It is shown that obtained materials have high values of capacitance which is realized by charge storage on the electrical double layer and by pseudocapacitive ion storage on the surface of the material. It is established that based on NCM, electrochemical capacitors are stable in all range of current density and material capacity essentially depends on appropriate choice of electrolyte. PMID:26759354

  2. Temperature sensitivity of organic carbon mineralization in contrasting lake sediments

    OpenAIRE

    Gudasz, Cristian; Sobek, Sebastian; Bastviken, David; Koehler, Birgit; Tranvik, Lars J.

    2015-01-01

    Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contribut...

  3. Does soil fauna increase carbon mineralization or carbon sequestration in soil

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan

    České Budějovice : Institute of Soil Biology BC AS CR, 2009. s. 22. [Central European Workshop on Soil Zoology /10./. 21.04.2009-24.04.2009, České Budějovice] Institutional research plan: CEZ:AV0Z60660521 Keywords : soil fauna * carbon mineralization * carbon sequestration Subject RIV: EH - Ecology, Behaviour

  4. Supercritical aqueous fluids in subduction zones carrying carbon and sulfur: oxidants for the mantle wedge?

    Science.gov (United States)

    Sverjensky, Dimitri; Manning, Craig

    2014-05-01

    Much speculation surrounds the nature of aqueous fluids in subduction zones. Aqueous fluids likely trigger partial melting in the mantle wedge, influencing the chemistry of the magmas that erupt in island arcs. They also may play a role in transporting elements that could metasomatize and oxidize the overlying mantle wedge, most importantly C, S and Fe. However, full coupling of aqueous fluid chemistry with the silicate, carbonate, C, sulfide and sulfate minerals has remained limited to pressures of 0.5 GPa because of limitations on the HKF aqueous ion equation of state. Recent progress in developing a Deep Earth Water model (Sverjensky et al., 2014), calibrated with new experimental data, now enables a detailed evaluation of the evolution of aqueous fluid chemistry to a pressure of 6 GPa, well into subduction zone conditions. We report aqueous speciation models for eclogitic aqueous fluids constrained by model mineral assemblages that give preliminary indications of the solubilities of elements that could contribute to mass transfer and redox changes in the mantle wedge. For example, at 600 °C and 2.5 GPa, an aqueous fluid in equilibrium with jadeite, paragonite, muscovite, quartz, lawsonite, almandine, talc, magnesite and pyrite at QFM oxidation state with 0.1 molal total Cl, contains 5.5 molal C, 0.04 molal S, and 9 micromolal Fe. The fluid has a pH of 4.7, much greater than the neutral pH of 3.3; the predominant species and molalities are CO2 (5.0), Na+ (0.44), Si(OH)4 (0.36), HCO3- (0.26), H3SiO4- (0.23), CaHCO3+ (0.18), silica dimer (0.10), Cl- (0.09), K+ (0.08), HCOO- (0.06), H2S (0.03). Calculations for model eclogitic fluids at the higher pressures and temperatures of subarc conditions also show that the solubility of C is much greater than either S or Fe at QFM. However, in subarc eclogitic fluids of higher oxidation state (QFM +3 to +4) in equilibrium with hematite, anhydrite, jadeite, kyanite, phlogopite, coesite, lawsonite, almandine-pyrope, and

  5. Sorption of a phenols mixture in aqueous solution with activated carbon

    International Nuclear Information System (INIS)

    The constant population growth and the quick industrialization have caused severe damages to our natural aquifer resources for a great variety of organic and inorganic pollutants. Among these they are those phenol compounds that are highly toxic, resistant (to the degradation chemistry) and poorly biodegradable. The phenolic compounds is used in a great variety of industries, like it is the production of resins, nylon, plastifiers, anti-oxidants, oil additives, drugs, pesticides, colorants, explosives, disinfectants and others. The disseminated discharges or effluents coming from the industrial processes toward lakes and rivers are causing a growing adverse effect in the environment, as well as a risk for the health. Numerous studies exist on the phenols removal and phenols substituted for very varied techniques, among them they are the adsorption in activated carbon. This finishes it has been used successfully for the treatment of residual waters municipal and industrial and of drinking waters and it is considered as the best technique available to eliminate organic compounds not biodegradable and toxic present in aqueous solution (US EPA, 1991). However a little information exists on studies carried out in aqueous systems with more of a phenolic compound. The activated carbon is broadly used as adsorbent due to its superficial properties in the so much treatment of water as of aqueous wastes, adsorbent for the removal of organic pollutants. The main objective of this work is the adsorption of a aqueous mixture of phenol-4 chloro phenol of different concentrations in activated carbon of mineral origin of different meshes and to diminish with it their presence in water. The experiments were carried out for lots, in normal conditions of temperature and pressure. The experimental results show that the removal capacity depends so much of the superficial properties of the sorbent like of the physical properties and chemical of the sorbate. The isotherms were carried

  6. A review of mineral carbonation technologies to sequester CO2.

    Science.gov (United States)

    Sanna, A; Uibu, M; Caramanna, G; Kuusik, R; Maroto-Valer, M M

    2014-12-01

    Carbon dioxide (CO2) capture and sequestration includes a portfolio of technologies that can potentially sequester billions of tonnes of CO2 per year. Mineral carbonation (MC) is emerging as a potential CCS technology solution to sequester CO2 from smaller/medium emitters, where geological sequestration is not a viable option. In MC processes, CO2 is chemically reacted with calcium- and/or magnesium-containing materials to form stable carbonates. This work investigates the current advancement in the proposed MC technologies and the role they can play in decreasing the overall cost of this CO2 sequestration route. In situ mineral carbonation is a very promising option in terms of resources available and enhanced security, but the technology is still in its infancy and transport and storage costs are still higher than geological storage in sedimentary basins ($17 instead of $8 per tCO2). Ex situ mineral carbonation has been demonstrated on pilot and demonstration scales. However, its application is currently limited by its high costs, which range from $50 to $300 per tCO2 sequestered. Energy use, the reaction rate and material handling are the key factors hindering the success of this technology. The value of the products seems central to render MC economically viable in the same way as conventional CCS seems profitable only when combined with EOR. Large scale projects such as the Skyonic process can help in reducing the knowledge gaps on MC fundamentals and provide accurate costing and data on processes integration and comparison. The literature to date indicates that in the coming decades MC can play an important role in decarbonising the power and industrial sector. PMID:24983767

  7. The efficiency of CO{sub 2} sequestration via carbonate mineralization with simulated wastewaters of high salinity

    Energy Technology Data Exchange (ETDEWEB)

    Mignardi, S., E-mail: silvano.mignardi@uniroma1.it [Dipartimento di Scienze della Terra, Sapienza Universita di Roma, P.le Aldo Moro 5, I-00185 Roma (Italy); De Vito, C.; Ferrini, V. [Dipartimento di Scienze della Terra, Sapienza Universita di Roma, P.le Aldo Moro 5, I-00185 Roma (Italy); Martin, R.F. [Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, QC H3A 2A7 (Canada)

    2011-07-15

    Salinity generally strongly affects the solubility of carbon dioxide in aqueous solution. This would seem to involve a reduction of the efficiency of the carbonate mineralization process with the objective to sequester this greenhouse gas. On the contrary, we demonstrate here that with a more concentrated solution of magnesium chloride, the residence time of CO{sub 2} is enhanced in the aqueous medium because of a reduced tendency to produce CO{sub 2(g)}. Experiments intended to simulate more closely the Mg-rich wastewaters that are industrially available have been carried out using solutions differing in Mg concentration (7, 16, 32 g L{sup -1} Mg). A comparison of the efficiency of the CO{sub 2} mineralization process among sets of experiments shows that the reduction of the efficiency, to about 65%, was lower than that expected, as the low degree of CO{sub 2} degassing results in the enhanced availability of carbonic ions to react with Mg ions to form stable carbonate minerals over a longer time.

  8. Effects of carbon substrate lability on carbon mineralization dynamics of tropical peat

    Science.gov (United States)

    Jauhiainen, Jyrki; Silvennoinen, Hanna; Könönen, Mari; Limin, Suwido; Vasander, Harri

    2016-04-01

    Extensive draining at tropical ombrotrophic peatlands in Southeast Asia has made them global 'hot spots' for greenhouse gas emissions. Management practises and fires have led to changed substrate status, which affects microbial processes. Here, we present the first data on how management practises affect carbon (C) mineralization processes at these soils. We compared the carbon mineralization potentials of pristine forest soils to those of drained fire affected soils at various depths, with and without additional labile substrates (glucose, glutamate and NO3-N) and in oxic and anoxic conditions by dedicated ex situ experiments. Carbon mineralization (CO2 and CH4 production) rates were higher in the pristine site peat, which contains more labile carbon due to higher input via vegetation. Production rates decreased with depth together with decreasing availability of labile carbon. Consequently, the increase in production rates after labile substrate addition was relatively modest from pristine site as compared to the managed site and from the top layers as compared to deeper layers. Methanogenesis had little importance in total carbon mineralization. Adding labile C and N enhanced heterotrophic CO2 production more than the sole addition of N. Surprisingly, oxygen availability was not an ultimate requirement for substantial CO2 production rates, but anoxic respiration yielded comparable rates, especially at the pristine soils. Flooding of these sites will therefore reduce, but not completely cease, peat carbon loss. Reintroduced substantial vegetation and fertilization in degraded peatlands can enrich recalcitrant peat with simple C and N compounds and thus increase microbiological activity.

  9. Removal of phosphate ions from aqueous solution using Tunisian clays minerals and synthetic zeolite

    Institute of Scientific and Technical Information of China (English)

    Noureddine Hamdi; Ezzeddine Srasra

    2012-01-01

    Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water.From the environmental point of view,the management of such contaminant and valuable resource is very important.The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent.The pH effect and adsorption kinetic were studied.It was found that phosphate could be efficiently removed at acidic pH (between 4 and 6) and the second order model of kinetics is more adopted for all samples.The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake (52.9 mg P/g).Equilibrium data were well fitted with Langmuir and Freundlich isotherm.

  10. A method for monitoring mineralization of 14C-labeled compounds in aqueous samples

    International Nuclear Information System (INIS)

    Previously reported laboratory methods for measuring the rate of 14CO2 release from an aqueous sample require a series of replicate growth flasks. At chosen times, some of these are sacrificed in order to quantitate the 14CO2 released. The method presented here requires only one culture flask containing 200 ml of sample with labeled substrate, and one control-replacement flask containing 200 ml of sterile sample with labeled substrate. At each sampling time, 1/40th of the liquid and headspace gas is removed from the modified 500 ml Erlenmeyer culture flask for 14CO2 recovery. This method was used to study the mineralization of labeled amino acids, starch, n-hexadecane and anthracene by micro-organisms in river water, and of n-hexadecane and n-hexadecanoic acid by microorganisms in sewage effluent. (author)

  11. Removal of phosphate ions from aqueous solution using Tunisian clays minerals and synthetic zeolite.

    Science.gov (United States)

    Hamdi, Noureddine; Srasra, Ezzeddine

    2012-01-01

    Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valuable resource is very important. The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent. The pH effect and adsorption kinetic were studied. It was found that phosphate could be efficiently removed at acidic pH (between 4 and 6) and the second order model of kinetics is more adopted for all samples. The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake (52.9 mg P/g). Equilibrium data were well fitted with Langmuir and Freundlich isotherm. PMID:22894095

  12. Ternary diffusion of carbon dioxide in alkaline solutions of aqueous sodium hydroxide and aqueous sodium carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Leaist, D.G.

    1985-07-01

    Carbon dioxide dissolved in alkaline solutions diffuses as bicarbonate and carbonate ions produced by the reactions CO/sub 2/+OH/sup -/=HCO/sub 3//sup -/ and CO/sub 2/+2OH/sup -/=CO/sub 3//sup 2 -/+H/sub 2/O. Ternary diffusion coefficients of the systems NaHCO/sub 3/+Na/sub 2/CO/sub 3/+H/sub 2/O and Na/sub 2/CO/sub 3/+NaOH+H/sub 2/O have been measured by a conductimetric technique at 298.15 K. The mixed electrolyte data are transformed by use of the solution equilibria to ternary diffusion coefficients of the systems CO/sub 2/+Na/sub 2/CO/sub 3/+H/sub 2/O and CO/sub 2/+NaOH+H/sub 2/O. Unlike the binary diffusivity of CO/sub 2/ in water (1.9 . 10/sup -9/ m/sup 2/ s/sup -1/), the ternary diffusivity of CO/sub 2/ in alkaline solutions is sensitive to concentration and varies from 0.9 . 10/sup -9/ to 3.5 . 10/sup -9/ m/sup 2/ s/sup -1/ at 298.15 K. Expressions are derived to estimate the transport coefficients of the components from the concentrations and diffusion coefficients of the constituent ions. At high pH values hydroxide-coupled transport leads to rapid diffusion of CO/sub 2/ as CO/sub 3//sup 2 -/. The results are consistent with the Onsager reciprocal relation for isothermal ternary diffusion.

  13. Permanent storage of carbon dioxide in geological reservoirs by mineral carbonation

    Science.gov (United States)

    Matter, Jürg M.; Kelemen, Peter B.

    2009-12-01

    Anthropogenic greenhouse-gas emissions continue to increase rapidly despite efforts aimed at curbing the release of such gases. One potentially long-term solution for offsetting these emissions is the capture and storage of carbon dioxide. In principle, fluid or gaseous carbon dioxide can be injected into the Earth's crust and locked up as carbonate minerals through chemical reactions with calcium and magnesium ions supplied by silicate minerals. This process can lead to near-permanent and secure sequestration, but its feasibility depends on the ease and vigour of the reactions. Laboratory studies as well as natural analogues indicate that the rate of carbonate mineral formation is much higher in host rocks that are rich in magnesium- and calcium-bearing minerals. Such rocks include, for example, basalts and magnesium-rich mantle rocks that have been emplaced on the continents. Carbonate mineral precipitation could quickly clog up existing voids, presenting a challenge to this approach. However, field and laboratory observations suggest that the stress induced by rapid precipitation may lead to fracturing and subsequent increase in pore space. Future work should rigorously test the feasibility of this approach by addressing reaction kinetics, the evolution of permeability and field-scale injection methods.

  14. Experimental studies on removal of carbon dioxide by aqueous ammonia fine spray

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Experimental studies on carbon dioxide capture in a spray scrubber were carried out.Fine spray of aqueous ammonia was used as CO2 absorbent.Effects of different operating and design parameters on CO2 removal efficiency including concentration of aqueous ammonia,liquid flow rate,total gas flow rate,initial temperature and concentration of carbon dioxide were investigated.

  15. Temperature sensitivity of organic carbon mineralization in contrasting lake sediments

    Science.gov (United States)

    Gudasz, Cristian; Sobek, Sebastian; Bastviken, David; Koehler, Birgit; Tranvik, Lars J.

    2015-07-01

    Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21°C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (Ea). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32 years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.

  16. Soil Organic Carbon Loss: An Overlooked Factor in the Carbon Sequestration Potential of Enhanced Mineral Weathering

    Science.gov (United States)

    Dietzen, Christiana; Harrison, Robert

    2016-04-01

    Weathering of silicate minerals regulates the global carbon cycle on geologic timescales. Several authors have proposed that applying finely ground silicate minerals to soils, where organic acids would enhance the rate of weathering, could increase carbon uptake and mitigate anthropogenic CO2 emissions. Silicate minerals such as olivine could replace lime, which is commonly used to remediate soil acidification, thereby sequestering CO2 while achieving the same increase in soil pH. However, the effect of adding this material on soil organic matter, the largest terrestrial pool of carbon, has yet to be considered. Microbial biomass and respiration have been observed to increase with decreasing acidity, but it is unclear how long the effect lasts. If the addition of silicate minerals promotes the loss of soil organic carbon through decomposition, it could significantly reduce the efficiency of this process or even create a net carbon source. However, it is possible that this initial flush of microbial activity may be compensated for by additional organic matter inputs to soil pools due to increases in plant productivity under less acidic conditions. This study aimed to examine the effects of olivine amendments on soil CO2 flux. A liming treatment representative of typical agricultural practices was also included for comparison. Samples from two highly acidic soils were split into groups amended with olivine or lime and a control group. These samples were incubated at 22°C and constant soil moisture in jars with airtight septa lids. Gas samples were extracted periodically over the course of 2 months and change in headspace CO2 concentration was determined. The effects of enhanced mineral weathering on soil organic matter have yet to be addressed by those promoting this method of carbon sequestration. This project provides the first data on the potential effects of enhanced mineral weathering in the soil environment on soil organic carbon pools.

  17. IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg

    Science.gov (United States)

    De Visscher, Alex; Vanderdeelen, Jan; Königsberger, Erich; Churagulov, Bulat R.; Ichikuni, Masami; Tsurumi, Makoto

    2012-03-01

    The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO3), nesquehonite (MgCO3.3H2O), and lansfordite (MgCO3.5H2O), a critical evaluation is presented based on curve fits to empirical and/or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO2 with Sechenov parameters, and for various equilibria in the aqueous phase including the dissociation constants of CO2(aq) and the stability constant of the ion pair MCO30(aq) (M = alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consistent with two thermodynamic model variants are proposed. The model variant that describes the Mg2+-HCO3- ion interaction with Pitzer parameters was more consistent with the solubility data and with other thermodynamic data than the model variant that described the interaction with a stability constant.

  18. Measurement of contact angles of aqueous solutions on some rock forming minerals

    Science.gov (United States)

    Takakura, M.; Katsura, M.; Nakashima, S.

    2007-12-01

    Wetting properties of fluids on earth's materials are controlling fluid flows and dynamics of the geological systems. Although the wetting behavior of industrial materials have been widely examined often by contact angle measurements, contact angles of rock-forming materials have not been commonly measured. Therefore, we have been measuring contact angles of some representative rock-forming minerals. The surfaces of solid samples were polished successively by emery papers then by grinding powders (alumina: up to \\sharp3000: grain size about 5 micrometers). Water droplet from a micro-syringe needle are placed on solid surfaces by moving up the sample stage. Images of water drops on the solid surfaces are captured from the horizontal direction with a CCD camera. Contact angles can be determined from the height and the length of the images by assuming them to be parts of circles. Over 60 measurements of contact angles of pure water on (101) and (011) faces plates cut from a natural quartz single crystal were repeated. The average contact angles of pure water on (101) and (011) faces of quartz were 48 ± 5 degrees and 52 ± 3 degrees, respectively. Contact angles of pure water on a natural calcite single crystal was also measured in the same way to be 37 ± 8 degrees. Contact angles of various aqueous solutions such as NaCl and NaHCO3 on these minerals will also be measured in order to evaluate wetting properties of natural rock-water systems.

  19. Carbon Mineralization in Acidic, Xeric Forest Soils: Induction of New Activities †

    OpenAIRE

    Tate, Robert L.

    1985-01-01

    Carbon mineralization was examined in Lakehurst and Atsion sands collected from the New Jersey Pinelands and in Pahokee muck from the Everglades Agricultural Area. Objectives were (i) to estimate the carbon mineralization capacities of acidic, xeric Pinelands soils in the absence of exogenously supplied carbon substrate (nonamended carbon mineralization rate) and to compare these activities with those of agriculturally developed pahokee muck, and (ii) to measure the capacity for increased car...

  20. Ethylbenzene Removal by Carbon Nanotubes from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Bijan Bina

    2012-01-01

    Full Text Available The removal of ethylbenzene (E from aqueous solution by multiwalled, single-walled, and hybrid carbon nanotubes (MWCNTs, SWCNTs, and HCNTs was evaluated for a nanomaterial dose of 1 g/L, concentration of 10–100 mg/L, and pH 7. The equilibrium amount removed by SWCNTs (E: 9.98 mg/g was higher than by MWCNTs and HCNTs. Ethylbenzene has a higher adsorption tendency on CNTs, so that more than 98% of it adsorbed in first 14 min, which is related to the low water solubility and the high molecular weight. The SWCNTs performed better for ethylbenzene sorption than the HCNTs and MWCNTs. Isotherms study indicates that the BET isotherm expression provides the best fit for ethylbenzene sorption by SWCNTs. Carbon nanotubes, specially SWCNTs, are efficient and rapid adsorbents for ethylbenzene which possess good potential applications to maintain high-quality water. Therefore, it could be used for cleaning up environmental pollution to prevent ethylbenzene borne diseases.

  1. The efficiency of magnetic carbon activated by iron oxide nanoparticles in removing of Cu (II from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Salehe Salehnia

    2016-04-01

    Full Text Available Background and Aim: Copper ions, due to forming complexes with organic and mineral compounds, can have worrying effects on health and environment. In the present study, the effect of powdered magnetic carbon activated by iron-oxide nanoparticles in removing of CU (V; II from aqueous solutions was assessed. Materials and Methods: This experimental study aimed at determining the effect of powdered magnetic carbon activated  by iron-oxide nanoparticles  parameters including PH, contact time, absorbing dose, and initial concentration on copper(II removal .from aqueous solutions; through an indirect current. In order to assess the qualities of the synthetized adsorbent, TGA, FT-IR and SEM tests were applied. Residual concentration of copper was measured at 324nm wavelength by means of atomic absorption spectrometry flame. The obtained data was analyzed using Langmuir and Freundlich isotherm model. Result: It was found that synthetic nanoparticles(PH=10, with the adsorbent dosage of 1gr/l, can remove more than 96% of copper ions from aqueous solutions at 2 minutes. Also, the results showed that copper absorption pattern is more in accord with Langmuir model.  Conclusion: Based on the current findings , magnetic synthesized nanoparticles coated with carbon. are in sporadic form in aqueous solutions. and can easily be separated using external magnetic environment. Moreover, because of existant active carbon sites absorption in iron oxide structure suferficial absorbtion capacity increases and and these nanoparticles reveal to have a high performance in the removing process of copper pollutants from aqueous solutions.

  2. Strategies for enhancing the performance of carbon/carbon supercapacitors in aqueous electrolytes

    International Nuclear Information System (INIS)

    Presented paper describes and critically comments major recent strategies for improving electrochemical capacitor performance. Particularly, carbon based electrodes and aqueous electrolytes have been considered. A novel concept of redox active electrolytes as a source of pseudocapacitance effect as well as profits and cons of such system have been discussed. The electrochemical performance of capacitor operating in such electrolyte solution is reported. Furthermore, some advantageous features of bio-inspired system based on bromine-cerium solution acting as oscillator are also presented

  3. Fundamental Science for Geologic Carbon Sequestration: Molecular Probes for Understanding Wet CO2 Interaction with Caprock Minerals (Invited)

    Science.gov (United States)

    Rosso, K. M.; White, D.; Murphy, E. M.; Hu, J.; Hoyt, D. W.; Wang, Z.; Lea, A. S.; Schaef, H. T.; McGrail, P.

    2009-12-01

    Capture and storage of carbon dioxide and other greenhouse gases in deep geologic formations represents one of the most promising options for minimizing the impacts of greenhouse gases on climate change. A critical issue is to demonstrate in a scientifically defensible manner that CO2 will remain stored over the long-term in the geological formation where it is injected. With regards to mineral-fluid interaction, the majority of previous research has focused on mineral reactivity in aqueous solutions containing CO2. However, at the caprock-fluid interface, interaction with the supercritical CO2 (scCO2) phase itself may become more important as the buoyant plume slowly displaces or dessicates residual aqueous solution. Mechanisms of mineral interfacial reactions with wet or water-saturated CO2 are unknown. The measurement of kinetic and thermodynamic data for mineral transformation reactions in these fluids present unique challenges. New experimental tools under development at Pacific Northwest National Laboratory are enabling in situ characterization of mineral transformation processes in scCO2/H2O fluids with molecular resolution. 29Si and 13C magic angle sample spinning nuclear magnetic resonance spectroscopy of metal carbonation reactions of model magnesium silicate minerals (e.g., Mg2SiO4 forsterite) in scCO2 shows initial transformation to MgCO3 magnesite within 20 hours at 80 atm and 80°C only when water is present for nucleophilic attack on Mg-O-Si. High pressure infrared spectroscopy detects unique spectral signatures for H2O and D2O dissolved in trace quantities (mineral surfaces in contact with scCO2 fluids. High-pressure x-ray diffraction will enable phase identification in situ. Collectively, this set of capabilities provides a unique platform for elucidating the role of water for catalyzing mineral transformation to metal carbonates and provides a means for determining effective kinetic constants. Understanding and accurately representing chemical

  4. Sorption recovery of 137Cs and 90Sr with carbonate-containing natural mineral tripolite

    International Nuclear Information System (INIS)

    Sorption characteristics of a carbonate-containing mineral (tripolite) were studied on model aqueous solutions and real waste water in a wide range of pH in the presence of isotopic and nonisotopic carriers and organic impurities. Sorption of 137Cs and 90Sr is adequately described by a power function. Analysis of 137Cs sorption isotherms suggests that radiocesium is adsorbed by ion-exchange mechanism, during which Cs+ ions from the solution exchange mainly with bivalent ions of the sorbent, whereas in 90Sr sorption trivalent ions of the sorbent also participate in the process. Saturation capacity of tripolite with respect to cesium and strontium was evaluated to be 0.3 and 1.0 mg-equiv./g respectively

  5. Mineral Influence on Microbial Survival During Carbon Sequestration

    Science.gov (United States)

    Santillan, E. U.; Shanahan, T. M.; Wolfe, W. W.; Bennett, P.

    2012-12-01

    CO2 sequestered in a deep saline aquifer will perturb subsurface biogeochemistry by acidifying the groundwater and accelerating mineral diagenesis. Subsurface microbial communities heavily influence geochemistry through their metabolic processes, such as with dissimilatory iron reducing bacteria (DIRB). However, CO2 also acts as a sterilant and will perturb these communities. We investigated the role of mineralogy and its effect on the survival of microbes at high PCO2 conditions using the model DIRB Shewanella oneidensis MR-1. Batch cultures of Shewanella were grown to stationary phase and exposed to high PCO2 using modified Parr reactors. Cell viability was then determined by plating cultures after exposure. Results indicate that at low PCO2 (2 bar), growth and iron reduction are decreased and cell death occurs within 1 hour when exposed to CO2 pressures of 10 bar or greater. Further, fatty acid analysis indicates microbial lipid degradation with C18 fatty acids being the slowest lipids to degrade. When cultures were grown in the presence of rocks or minerals representative of the deep subsurface such as carbonates and silicates and exposed to 25 bar CO2, survival lasted beyond 2 hours. The most effective protecting substratum was quartz sandstone, with cultures surviving beyond 8 hours of CO2 exposure. Scanning electron microscope images reveal biofilm formation on the mineral surfaces with copious amounts of extracellular polymeric substances (EPS) present. EPS from these biofilms acts as a reactive barrier to the CO2, slowing the penetration of CO2 into cells and resulting in increased survival. When biofilm cultures were grown with Al and As to simulate the release of toxic metals from minerals such as feldspars and clays, survival time decreased, indicating mineralogy may also enhance microbial death. Biofilms were then grown on iron-coated quartz sand to determine conversely what influence biofilms may have on mineral dissolution during CO2 perturbation

  6. Influence of the particle size of activated mineral carbon on the phenol and chlorophenol adsorption

    International Nuclear Information System (INIS)

    Water pollution by phenolic compounds is a problem that requires a solution since these phenolic compounds are not completely biodegradable, they accumulate through the food chains and they are quite toxic when enter in contact with living organisms. In human beings, ingestion or contact of the skin with this type of compounds produces irritation and damages mainly to the liver and kidneys. In fact, the Environmental Protection Agency of the United States (EPA assigned nine phenolic compounds among the 275 most toxic substances in 1991. Phenols are found in wastewater from agriculture and industry, because phenolic compounds are used as pesticides and in diverse industrial activities. The treatment of this type of water is not simple because they are generally composed of a mixture of residuals with different chemical nature A useful method for the removal of phenols is the adsorption by activated carbon, since this material has a great surface area and it can be regenerated. The adsorption process depends, among other factors, on the activated carbon characteristics. When they are modified, their capacity to remove pollutants from the water changes. The effect of activated carbon particle size on the removal of phenolic compounds has not been completely studied. Therefore, the aim of this work was to determine the influence of the mineral activated carbon particle size on the phenol and 4-chloro phenol adsorption in aqueous solution, on adsorption column system. The results of the present work indicate that the mineral activated carbon particle size has a very important influence on the adsorption of phenol and 4-chloro phenol. When the particles were smaller, the retention quantities of phenol and 4-chloro phenol increased. This behavior was related to the particle characteristics of the mineral activated carbon such as surface area and pore volume, while other factors such as elementary composition of the activated carbon did not influence the adsorption process

  7. Development of a Rapid, Nondestructive Method to Measure Aqueous Carbonate in High Salinity Brines Using Raman Spectroscopy

    Science.gov (United States)

    McGraw, L.; Phillips-Lander, C. M.; Elwood Madden, A. S.; Parnell, S.; Elwood Madden, M.

    2015-12-01

    Traditional methods of quantitative analysis are often ill-suited to determining the bulk chemistry of high salinity brines due to their corrosive and clogging properties. Such methods are also often difficult to apply remotely in planetary environments. However, Raman spectroscopy can be used remotely without physical contact with the fluid and is not affected by many ionic brines. Developing methods to study aqueous carbonates is vital to future study of brines on Mars and other planetary bodies, as they can reveal important information about modern and ancient near-surface aqueous processes. Both sodium carbonate standards and unknown samples from carbonate mineral dissolution experiments in high salinity brines were analyzed using a 532 nm laser coupled to an inVia Renishaw spectrometer to collect carbonate spectra from near-saturated sodium chloride and sodium sulfate brines. A calibration curve was determined by collecting spectra from solutions of known carbonate concentrations mixed with a pH 13 buffer and a near-saturated NaCl or Na2SO4 brine matrix. The spectra were processed and curve fitted to determine the height ratio of the carbonate peak at 1066 cm-1 to the 1640 cm-1 water peak. The calibration curve determined using the standards was then applied to the experimental data after accounting for dilutions. Concentrations determined based on Raman spectra were compared against traditional acid titration measurements. We found that the two techniques vary by less than one order of magnitude. Further work is ongoing to verify the method and apply similar techniques to measure aqueous carbonate concentrations in other high salinity brines.Traditional methods of quantitative analysis are often ill-suited to determining the bulk chemistry of high salinity brines due to their corrosive and clogging properties. Such methods are also often difficult to apply remotely in planetary environments. However, Raman spectroscopy can be used remotely without physical

  8. Direct mineral carbonation of steelmaking slag for CO2 sequestration at room temperature.

    Science.gov (United States)

    Rushendra Revathy, T D; Palanivelu, K; Ramachandran, A

    2016-04-01

    Rapid increase of CO2 concentration in the atmosphere has forced the international community towards adopting actions to restrain from the impacts of climate change. Moreover, in India, the dependence on fossil fuels is projected to increase in the future, implying the necessity of capturing CO2 in a safe manner. Alkaline solid wastes can be utilized for CO2 sequestration by which its disposal issues in the country could also be met. The present work focuses to study direct mineral carbonation of steelmaking slag (SS) at room temperature and low-pressure conditions (carbonation of SS was carried out in a batch reactor with pure CO2 gas. The process parameters that may influence the carbonation of SS, namely, CO2 gas pressure, liquid to solid ratio (L/S) and reaction time were also studied. The results showed that maximum sequestration of SS was attained in the aqueous route with a capacity of 82 g of CO2/kg (6 bar, L/S ratio of 10 and 3 h). In the gas-solid route, maximum sequestration capacity of about 11.1 g of CO2/kg of SS (3 bar and 3 h) was achieved indicating that aqueous route is the better one under the conditions studied. These findings demonstrate that SS is a promising resource and this approach could be further developed and used for CO2 sequestration in the country. The carbonation process was evidenced using FT-IR, XRD, SEM and TG analysis. PMID:26681331

  9. Numerical models of carbonate hosted gold mineralization, Great Basin Nevada

    Science.gov (United States)

    Person, M.; Hofstra, A.; Gao, Y.; Sweetkind, D.; Banerjee, A.

    2006-12-01

    The Great Basin, Nevada contains many modern hydrothermal system and world class gold deposits hosted within Paleozoic carbonate rocks. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern geothermal and fossil hydrothermal systems associated with gold mineralization share many common features including the absence of a clear magmatic source, flow restricted to fault zones, and remarkably high temperatures at shallow depth. While the plumbing of these systems is not well understood, geochemical and isotopic data suggest that fluid circulation along fault zones is relatively deep (greater than 5 km) and comprised of relatively unexchanged Pleistocene meteoric water with small (less than 2.5 per mill) shifts from the MWL. Many fossil ore-forming systems were also dominated by meteoric water, but are usually exhibit shifts of 5 to 15 per mill from the MWL. Here we present two-dimensional numerical models to reconstruct the plumbing of modern geothermal and Tertiary hydrothermal systems in the Great Basin. Multiple tracers are used in our models, including O- and C-isotopic compositions of fluids/rocks, silica transport/ precipitation, and temperature anomalies, to constrain the plumbing of these systems. Our results suggest that both fossil hydrothermal and modern geothermal systems were probably driven by natural convection cells associated with localized high basal heating. We conclude that the fault controlled flow systems responsible for the genesis of Carlin gold mineralization and modern geothermal systems had to be transient in nature. Permeability changes within the carbonate reservoir was probably associated with extensional tectonic events.

  10. Modeling of induced seismicity during mineral carbon sequestration

    Science.gov (United States)

    Yarushina, V.; Bercovici, D. A.

    2013-12-01

    Rapidly developing carbon capture and storage (CCS) technologies are a promising way of reducing the climate impact of greenhouse gases. These technologies involve injecting large amounts of CO2-bearing fluids underground, which potentially leads to high pore pressure and the conditions for seismic activity in the proximity of the injection site. Previously, we developed a simple conceptual model to estimate the seismic risk of mineral or mafic CCS operations (Yarushina & Bercovici, GRL vol.40, doi:10.1002/grl.50196, 2013). In this model, the storage reservoir is treated as a porous rock with grains that evolve during carbonation reactions. Seismic triggering occurs when local stresses at grain-grain contacts reach the Mohr-Coulomb failure criterion. We showed that injection of CO2 into reactive mafic or ultramafic rocks potentially reduces seismic risk since carbonation reactions increase the contact area between the rock grains and reduce the local stresses. Here we further develop this model and consider the effect of fluid injection flux and pressure gradients along grain boundaries on induced seismicity. Grain evolution not only changes the stress support but also alters the matrix permeability, which in turn affects the driving pressure gradients and the associated deviatoric stresses. The resulting coupled porous flow, chemical reactive grain-growth and failure model is an important step in understanding the seismic risks of carbon sequestration.

  11. Mineral Carbonation for Long-term CO2 Storage: an Exergy Analysis

    OpenAIRE

    Zevenhoven, Ron; Kavaliauskaite, Inga

    2004-01-01

    Magnesium oxide-based minerals (serpentine, olivine) may be used for long-term storage of CO2, from combustion of fossil fuels or industrial processes in the form of magnesium carbonate. Large resources of suitable minerals appear to exist in Finland and at many other locations worldwide. The efficiency of mineral carbonation processing can be evaluated using exergy analysis, which will allow for comparing different mineral types characterised by different composition and quality. Other impor...

  12. Sulfate Mineral Formation from Acid-weathered Phyllosilicates: Implications for the Aqueous History of Mars

    Science.gov (United States)

    Craig, Patricia; Ming, Douglas; Rampe, Elizabeth

    2014-11-01

    Phyllosilicates on Mars are common in Noachian terrains whereas sulfates are found in the younger Hesperian terrains and suggest alteration under more acidic conditions. Phyllosilicates that formed during the Noachian era would have been exposed to the prevailing acidic conditions during the Hesperian. The purpose of this project is to characterize the effects of acid-weathering on phyllosilicates to better understand the aqueous history of Mars. Nontronite, montmorillonite, and saponite were exposed to H2SO4 solutions at water-rock (WR) ratios of 50 and 25.X-ray diffraction (XRD) patterns of all three acid-treated minerals showed progressive collapse of the phyllosilicate basal spacing with increasing acid concentration. Bassanite formed as an intermediate phase in weathered nontronite and montmorillonite from extracted interlayer Ca. The octahedral cation determined which sulfate formed at high acid concentration: rhomboclase from nontronite, alunogen from montmorillonite, hexahydrite and kieserite from saponite. Gypsum and anhydrite also formed as intermediate phases in nontronite treated at WR=25, showing a change in sulfate hydration state with changing acid concentration (i.e. water activity). Scanning electron microscopy analyses detected phases not identified by XRD. Al-sulfate was found in nontronite weathered at WR=25 and Ca-sulfate in weathered saponite. Near-infrared reflectance spectra of the weathered samples showed decreasing intensity of the hydration/hydroxylation bands and a change or disappearance of metal-OH bands indicating dehydration and dissociation of the interlayers and octahedral layers, respectively, with increased acid weathering.Sulfate mineral formation from acid-weathered phyllosilicates may explain the presence of phyllosilicates and sulfates in close proximity to each other on Mars, such as in Gale Crater. The CheMin XRD instrument on Curiosity may find evidence for acid-weathered phyllosilicates in Mt. Sharp by comparing the 001

  13. Mineral carbonation in water-unsaturated porous media

    Science.gov (United States)

    Harrison, A. L.; Dipple, G. M.; Mayer, K. U.; Power, I. M.

    2014-12-01

    Ultramafic mine tailings have an untapped capacity to sequester CO2 directly from air or CO2-rich gas streams via carbonation of tailings minerals [1]. The CO2 sequestration capacity of these sites could be exploited simply by increasing the supply of CO2 into tailings, such as through circulation of air or flue gas from mine site power plants [1,2]. Mine tailings storage facilities typically have heterogeneously distributed pore water [1], affecting both the reactive capacity of the porous medium and the exposure of reactive phases to CO2 [3]. We examine the physical reaction processes that govern carbonation efficiency in variably saturated porous media using meter-scale column experiments containing the tailings mineral, brucite [Mg(OH)2], that were supplied with 10% CO2 gas streams. The experiments were instrumented with water content and gas phase CO2 sensors to track changes in water saturation and CO2concentration with time. The precipitation of hydrated Mg-carbonates as rinds encasing brucite particles resulted in passivation of brucite surfaces and an abrupt shut down of the reaction prior to completion. Moreover, the extent of reaction was further limited at low water saturation due to the lack of water available to form hydrated Mg-carbonates, which incorporate water into their crystal structures. Reactive transport modeling using MIN3P-DUSTY [4] revealed that the instantaneous reaction rate was not strongly affected by water saturation, but the reactive capacity was reduced significantly. Surface passivation and water-limited reaction resulted in a highly non-geometric evolution of reactive surface area. The extent of reaction was also limited at high water content because viscous fingering of the gas streams injected at the base of the columns resulted in narrow zones of highly carbonated material, but left a large proportion of brucite unreacted. The implication is that carbonation efficiency in mine tailings could be maximized by targeting an

  14. Ultrasound-assisted mineralization of organic compounds in aqueous liquid wastes

    International Nuclear Information System (INIS)

    Full text of publication follows: The rinsing of the nuclear installations used for the reprocessing of fuel irradiated before their final shutdown dismantling is considered by use of surface-active compounds diluted in nitric acid medium. In order to comply with the industrial vitrification specifications (carbon concentration in solution), mineralization (carbon decomposition into CO2) of liquid wastes has to be performed. An oxidation using H2O2 with nickel nitrate used as catalyst (Fenton reaction) is an efficient method for organics compounds destruction but it involves an important dilution because of added amounts of H2O2. Ultrasound associated or not with the Fenton reaction could be interesting with an aim of reducing H2O2 consumption. Indeed, it is known that water sono-lysis generates H2O2 involving radicals formation which may oxidize organics compounds. Laboratory tests have shown poor carbon oxidation performances even if associated with Fenton reaction. Efficiency is limited by nitrous acid, formed from nitric acid sono-lysis, enhancing H2O2 consumption. However, reaction mechanisms are complex and further tests, still in progress, will involve an anti nitrous agent in order to neutralize all nitrous acid and so let H2O2 operate on the organics compounds. (authors)

  15. Aqueous adsorption and removal of organic contaminants by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jin-Gang, E-mail: yujg@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Zhao, Xiu-Hui; Yang, Hua [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Chen, Xiao-Hong [Collaborative Innovation Center of Resource-conserving and Environment-friendly Society and Ecological Civilization, Changsha, Hunan 410083 (China); Yang, Qiaoqin [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada); Yu, Lin-Yan [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Jiang, Jian-Hui [College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Chen, Xiao-Qing, E-mail: xqchen@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China)

    2014-06-01

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. - Highlights: • We summarize the most recent research progress of CNTs for removal of organics. • Adsorption mechanisms between CNTs and organics were elucidated in detail. • The developing trends and prospects of CNTs for removal of organics were discussed.

  16. Aqueous adsorption and removal of organic contaminants by carbon nanotubes

    International Nuclear Information System (INIS)

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. - Highlights: • We summarize the most recent research progress of CNTs for removal of organics. • Adsorption mechanisms between CNTs and organics were elucidated in detail. • The developing trends and prospects of CNTs for removal of organics were discussed

  17. Application of Two Exponential Equations in the Study of Soil Organic Carbon Mineralization in Natural Forests

    Directory of Open Access Journals (Sweden)

    Pang Huan

    2014-10-01

    Full Text Available This study respective using the exponential equation and double exponential equation which are widely used were fitted Pinus massoniana, evergreen broad leaved forest, deciduous oak forest, pine-oak forest, Pinus koraiensis and Pinus tabulaeformis and other six kinds of typical natural forest soil organic carbon mineralization process, it also by fitting curves and cumulative release of CO2 mineralization process analysis and correlation of inert carbon content of soil measured and fitted values of t-test analysis, the two exponential equations in natural forest soil organic carbon mineralization process the application results were evaluated. The results show that the double exponential equation on soil organic carbon mineralization has a better fitting description effect can be more realistically reflect the changes in soil organic carbon mineralization characteristics of the fitting results of insert soil carbon content and measured values a significant difference is not level, the soil can be more accurately reflect the changes of the inert carbon.

  18. Removal of methylene blue from aqueous solution by fibrous clay minerals

    International Nuclear Information System (INIS)

    Kinetics and equilibrium processes of the methylene blue (MB) retention from aqueous solution by a mixture of fibrous clay minerals, which was isolated from a naturally occurring clay, were investigated. For these purposes, the effects of contact time, initial adsorbate concentration, adsorbent content, pH and ionic strength were determined. The results show that the MB retention obeys a pseudo-first order equation and the process is a diffusion controlled solid-state reaction. Moreover, the isotherm data fitted the Langmuir equation and the MB binding process became more energetic with the increase of the adsorbent concentration. In addition, the augmentation of the clay content or the initial MB concentration reduced the adsorption capacity, presumably because of the clay particles microaggregation and/or the occurrence of MB deriving species. On the other hand, it is observed that the MB uptake limit is reduced in low acid pH, particularly below the PZC, as well as in ionic strengthen solutions. These facts are linked to the silanol group protonation and to the reduction of the electrostatic forces induced by the clay particles, respectively

  19. Organic carbon production, mineralization and preservation on the Peruvian margin

    Directory of Open Access Journals (Sweden)

    A. W. Dale

    2014-09-01

    Full Text Available Carbon cycling in Peruvian margin sediments (11° S and 12° S was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC content was lowest on the inner shelf and at the deep oxygenated stations (< 5% and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%. The organic carbon burial efficiency (CBE was unexpectedly low on the inner shelf (< 20% when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%. Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09. Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

  20. A Quantitative Investigation of CO2 Sequestration by Mineral Carbonation

    CERN Document Server

    Mohammad, Muneer

    2015-01-01

    Anthropogenic activities have led to a substantial increase in carbon dioxide (CO2), a greenhouse gas (GHG), contributing to heightened concerns of global warming. In the last decade alone CO2 emissions increased by 2.0 ppm/yr. globally. In the year 2009, United States and China contributed up to 43.4% of global CO2 emissions. CO2 capture and sequestration have been recognized as promising solutions to mitigate CO2 emissions from fossil fuel based power plants. Typical techniques for carbon capture include post-combustion capture, pre-combustion capture and oxy-combustion capture, which are under active research globally. Mineral carbonation has been investigated as a suitable technique for long term storage of CO2. Sequestration is a highly energy intensive process and the additional energy is typically supplied by the power plant itself. This leads to a reduction in net amount of CO2 captured because of extra CO2 emitted. This paper presents a quantitative analysis of the energy consumption during sequestra...

  1. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    Science.gov (United States)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  2. Isotopic Fractionation of Mg2+(aq), Ca2+(aq), and Fe2+(aq) with Carbonate Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-15

    Density functional electronic structure calculations are used to compute the equilibrium constant (the isotope fractionation factor) for 26Mg/24Mg and 44Ca/40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 103ln(K) at 25 °C, of -5.3, -1.1, and +1.1 for 26Mg/24Mg exchange between calcite (CaCO3), magnesite (MgCO3), and dolomite (Ca0.5Mg0.5CO3), respectively, and Mg2+(aq), with positive values indicating enrichment in the mineral phase. For 44Ca/40Ca exchange between calcite and Ca2+(aq), the calculations predict values of +1.5 for Ca2+(aq) in six-fold coordination and +4.1 for Ca2+(aq) in seven-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO3)610- and M2+(H2O)6 embedded in a set of fixed atoms representing the 2nd shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using 2 the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe3+-hematite and Fe2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe3+(aq) and Fe2+(aq) species.

  3. Stability of Soil Carbon Fractions - Aggregation Versus Mineral Association

    Science.gov (United States)

    Mueller, C. W.; Koegel-Knabner, I.

    2007-12-01

    of CO2-C (70%) in the recombined fraction is the clay fraction. Nevertheless the recalcitrance of mineral bound C is restricting the positive effects of aggregate disruption on the C turnover. The small fast decomposing C pool of the sand fraction is of minor importance to the total soil respiration balance. CO2-13C signatures showed higher values of the silt and clay fractions in contrast to the sand fraction, indicating a lower bioavailability of 13C-depleted carbon sources in the small fractions. The analyses of CO2-14C showed a shift to the utilization of older C sources with time.

  4. Sorption of a mixture of phenols in aqueous solution with activated carbon; Sorcion de una mezcla de fenoles en solucion acuosa con carbon activado

    Energy Technology Data Exchange (ETDEWEB)

    Mejia M, D.; Lopez M, B.E.; Iturbe G, J.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    The main objective of this work is the sorption of an aqueous mixture of phenol-4 chloro phenol of different concentrations in a molar relationship 1:1 in activated carbon of mineral origin of different nets (10, 20 and 30) and to diminish with it its presence in water. The experimental results show that the removal capacity depends so much of the surface properties of the sorbent like of the physical and chemical properties of the sorbate. In all the cases it was observed that in the aqueous systems of low concentration the 4-chloro phenol are removed in an approximate proportion of 1.2-4 times greater to than phenol, however to concentrations but high both they are removed approximately in the same proportion. (Author)

  5. Synthesis of iron-based chemical looping sorbents integrated with pH swing carbon mineral sequestration.

    Science.gov (United States)

    Kim, Hyung Ray; Lee, Dong Hyun; Fan, Liang-Shih; Park, Ah-Hyung Alissa

    2009-12-01

    The previously developed pH swing carbon mineral sequestration immobilizes the gaseous CO2 into a thermodynamically stable solid, MgCO3, using Mg-bearing minerals such as serpentine. This mineral carbonation technology is particularly promising since it generates value-added solid products: high surface area silica, iron oxide, and magnesium carbonate, while providing a safe and permanent storage option for CO2. By carefully controlling the pH of the system, these solids products can be produced with high purity. This study focuses on the synthesis of iron oxide particles as a chemical looping sorbent in order to achieve the integration between carbon capture and storage technologies. Since the solubility of Fe in aqueous phase is relatively low at neutral pH, the effect of the weak acid and chelating agents on the extraction of Fe from serpentine was investigated. The synthesized iron-based chemical looping sorbent was found to be as effective as commercially available iron oxide nanoparticles at converting syngas into high purity H2, while producing a sequestration-ready CO2 stream. PMID:19908801

  6. Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

    Science.gov (United States)

    Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2016-09-01

    Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

  7. Ex-situ and in-situ mineral carbonation as a means to sequester carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Gerdemann, Stephen J.; Dahlin, David C.; O' Connor, William K.; Penner, Larry R.; Rush, G.E.

    2004-01-01

    The U. S. Department of Energy's Albany Research Center is investigating mineral carbonation as a method of sequestering CO2 from coal-fired-power plants. Magnesium-silicate minerals such as serpentine [Mg3Si2O5(OH)4] and olivine (Mg2SiO4) react with CO2 to produce magnesite (MgCO3), and the calcium-silicate mineral, wollastonite (CaSiO3), reacts to form calcite (CaCO3). It is possible to carry out these reactions either ex situ (above ground in a traditional chemical processing plant) or in situ (storage underground and subsequent reaction with the host rock to trap CO2 as carbonate minerals). For ex situ mineral carbonation to be economically attractive, the reaction must proceed quickly to near completion. The reaction rate is accelerated by raising the activity of CO2 in solution, heat (but not too much), reducing the particle size, high-intensity grinding to disrupt the crystal structure, and, in the case of serpentine, heat-treatment to remove the chemically bound water. All of these carry energy/economic penalties. An economic study illustrates the impact of mineral availability and process parameters on the cost of ex situ carbon sequestration. In situ carbonation offers economic advantages over ex situ processes, because no chemical plant is required. Knowledge gained from the ex situ work was applied to long-term experiments designed to simulate in situ CO2 storage conditions. The Columbia River Basalt Group (CRBG), a multi-layered basaltic lava formation, has potentially favorable mineralogy (up to 25% combined concentration of Ca, Fe2+, and Mg cations) for storage of CO2. However, more information about the interaction of CO2 with aquifers and the host rock is needed. Core samples from the CRBG, as well as samples of olivine, serpentine, and sandstone, were reacted in an autoclave for up to 2000 hours at elevated temperatures and pressures. Changes in core porosity, secondary mineralizations, and both solution and solid chemistry were measured.

  8. Shungites: origin and classification of a new carbon mineral resource

    Energy Technology Data Exchange (ETDEWEB)

    Ivankin, P.F.; Galdobina, L.P.; Kalinin, Yu.K.

    1987-10-01

    The discovery of a new mineral resource in Karelia-shungite- and the confirmation of the finding in the geological literature have a long history. In 1876, local peasants found black stones near the village of Shun'ga, which were taken to be coal and called Olenets anthracite. A discussion began on the nature of this strange anthracite, which did not burn in furnaces. The found of the Karelian geological school, A.A. Inostrantsev, was the first to doubt that Olenets anthracite was really coal, and he named it shungite. Shungites, very unusual, barely combustible high-carbon rocks, have a variety of potential uses. Although details remain obscure, the authors propose a metasomatic origin involving migration and reduction of carbonaceous compounds driven by igneous intrusions. 10 references.

  9. Carbon Mineralizability Determines Interactive Effects on Mineralization of Pyrogenic Organic Matter and Soil Organic Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Whitman, Thea L.; Zhu, Zihua; Lehmann, Johannes C.

    2014-10-31

    Soil organic carbon (SOC) is a critical and active pool in the global C cycle, and the addition of pyrogenic organic matter (PyOM) has been shown to change SOC cycling, increasing or decreasing mineralization rates (often referred to as priming). We adjusted the amount of easily mineralizable C in the soil, through 1-day and 6-month pre-incubations, and in PyOM made from maple wood at 350°C, through extraction. We investigated the impact of these adjustments on C mineralization interactions, excluding pH and nutrient effects and minimizing physical effects. We found short-term increases (+20-30%) in SOC mineralization with PyOM additions in the soil pre-incubated for 6 months. Over the longer term, both the 6-month and 1-day pre-incubated soils experienced net ~10% decreases in SOC mineralization with PyOM additions. This was possibly due to stabilization of SOC on PyOM surfaces, suggested by nanoscale secondary ion mass spectrometry. Additionally, the duration of pre-incubation affected priming interactions, indicating that there may be no optimal pre-incubation time for SOC mineralization studies. We show conclusively that relative mineralizability of SOC in relation to PyOM-24 C is an important determinant of the effect of PyOM additions on SOC mineralization.

  10. Adsorption of arsenic from aqueous media using lateritic minerals. Equilibrium, kinetic and thermodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Khalid, Nasir; Daud, Muhammad [Pakistan Institute of Nuclear Science and Technology, Islamabad (Pakistan). Chemistry Div.

    2014-07-01

    The sorption behavior of arsenic on minerals from a lateritic weathering has been investigated to evaluate its potential for the decontamination of arsenic ions from aqueous media. Various physicochemical parameters such as pH, equilibration time, adsorbent dose, concentration of adsorbate, effect of diverse ions and temperature were studied in order to simulate the best conditions under which this material can be used as an adsorbent, employing batch method and radiotracer technique. Maximum adsorption was observed in buffer solutions having pH of 2.0 and 8-9, using 0.5 g of adsorbent for 6.674 x 10{sup -5} mol L{sup -1} arsenic concentration in 10 min equilibration time. The sorption data followed the pseudo-second order reaction kinetics. The adsorption data fit both the Freundlich and Dubinin-Radushkevich isotherm equations over the range of 3.195 x 10{sup -5} to 3.195 x 10{sup -3} mol L{sup -1} arsenic concentration. The characteristic Freundlich constants i.e. 1/n = 0.427 ± 0.009 and K = 3.04 x 10{sup -4} ± 1.46 x 10{sup -5} mol g{sup -1} have been computed for the sorption system. The sorption mean free energy from the Dubinin-Radushkevich isotherm is 12.00 ± 0.38 kJ mol{sup -1} indicating ion-exchange mechanism of chemisorption. The uptake of arsenic increases with the rise in temperature (278.16-323.16 K). Thermodynamic quantities i.e.ΔG, ΔS and ΔH have also been calculated for the system. The sorption process was found to be endothermic. (orig.)

  11. Laser-induced breakdown spectroscopy analysis of minerals: Carbonates and silicates

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy (LIBS) provides an alternative chemical analytical technique that obviates the issues of sample preparation and sample destruction common to most laboratory-based analytical methods. This contribution explores the capability of LIBS analysis to identify carbonate and silicate minerals rapidly and accurately. Fifty-two mineral samples (18 carbonates, 9 pyroxenes and pyroxenoids, 6 amphiboles, 8 phyllosilicates, and 11 feldspars) were analyzed by LIBS. Two composite broadband spectra (averages of 10 shots each) were calculated for each sample to produce two databases each containing the composite LIBS spectra for the same 52 mineral samples. By using correlation coefficients resulting from the regression of the intensities of pairs of LIBS spectra, all 52 minerals were correctly identified in the database. If the LIBS spectra of each sample were compared to a database containing the other 51 minerals, 65% were identified as a mineral of similar composition from the same mineral family. The remaining minerals were misidentified for two reasons: 1) the mineral had high concentrations of an element not present in the database; and 2) the mineral was identified as a mineral with similar elemental composition from a different family. For instance, the Ca-Mg carbonate dolomite was misidentified as the Ca-Mg silicate diopside. This pilot study suggests that LIBS has promise in mineral identification and in situ analysis of minerals that record geological processes

  12. CO2 Sequestraion by Mineral Carbonation of Cement Material

    Science.gov (United States)

    Jo, H.; Jang, Y.

    2010-12-01

    CO2 sequestration by mineral carbonation with cement materials was investigated in this study. Ca extraction and CO2 injection tests were conducted on three different materials (lime, Portland cement, waste concrete) using different extract reagents (NH4Cl, CH3COOH, HCl, and Deionized water) under ambient temperature and pressure conditions. CO2 gas (99.9%) was injected to either supernatant without solids or suspension with solids obtained from extraction tests at 4 ml/min of flow rate. Ca concentrations were measured from filtered solutions before and after CO2 injection. The chemical and mineralogical composition of raw materials and precipitates were determined using X-ray fluorescence and X-ray diffraction, respectively. The morphology and chemical composition of precipitates were analyzed with Field Emission Scanning Electron Microscopy equipped with the Energy Dispersive X-ray analysis. For the extraction tests, Ca concentrations of the extracts were related with the CaO content and type of CaO bearing minerals of the materials, regardless of the extraction solutions. Lime had a higher Ca concentration ranging between 942.7 and 39945.0 mg/L in the extracts than waste concrete (188.4 ~ 2978.1 mg/L) in the extracts due to its higher content of CaO (CaO : 24.5% and waste concrete : 20.3%). In contrast, the Portland cement (6346.0 and 28903.5 mg/L) had lower Ca concentrations than lime (94.27 ~ 39945.0 mg/L), even though the Portland cement (56.3%) had a higher CaO content than lime (24.5%). For a given extraction solution, lime had the highest CO2 carbonation efficiency. In addition, for a given material, the CO2 carbonation efficiency was the highest when NH4Cl solution was used as an extraction solution. Results of material analyses indicate that precipitates from the CO2 injection tests consisted of mostly CaCO3, regardless of types of materials and extraction solutions.

  13. Heat optimisation of a staged gas-solid mineral carbonation process for long-term CO2 storage

    International Nuclear Information System (INIS)

    Carbonation of magnesium silicates offers an interesting option for CO2 emission mitigation in Finland, a country with large resources of serpentine-type minerals. Wet processes using aqueous solutions show reasonable chemical kinetics combined with poor energy economy. A dry, gas-solid process with slower chemical kinetics (demonstrated previously), but better energy economy could be an alternative. This paper addresses the energy economy of a two- or three-stage gas-solid process for magnesium silicate carbonation. It involves production of reactive magnesium as magnesium oxide or hydroxide in an atmospheric pressure step, followed by carbonation at elevated pressures that allow for reasonable carbonation reaction kinetics under conditions where magnesium carbonate is thermodynamically stable. For a feasible large-scale process the kinetics in the individual reactors must be fast enough, while the heat produced in the carbonation step must be sufficient to compensate for energy inputs to the preceding step(s). Results give reactor temperature combinations that allow for operation at a negative or zero energy input, for given carbonation reactor pressure and degree of carbonation conversion, and other process energy requirements. Softwares used were HSC and Aspen Plus. Also, some results from gas-solid kinetics studies with magnesium oxide-based materials at the pressures considered are included. (author)

  14. A fast and simple method for the determination of radium-226 in aqueous samples (drinking water, mineral water)

    International Nuclear Information System (INIS)

    A method is described which allows direct determination of the radium-226 content in aqueous samples within a few hours. An exchanger for specific ions on a PAC basis is used in a special application. The evaluation is based on the measurement of the 4.78 MeV α-particles of radium-226. The method is described, and its application to over 200 samples of drinking water and mineral water in the Federal Republic of Germany is reported. The average radium-226 concentration in drinking water from the Saarland is appr. 0.12 pCi of radium-226 per litre, and appr. 1.8 pCiof radium-226 per litre in mineral water from German mineral springs. (orig.)

  15. Sulfates on Mars as Markers of Aqueous Processes: An Integrated Multidisciplinary Study of Minerals, Mars Analog sites and Recent Mission Data

    Science.gov (United States)

    Bishop, J. L.; Lane, M. D.; Dyar, M. D.; Brown, A. J.; Parente, M.

    2006-01-01

    Our analyses of sulfate minerals, analog sites, and Martian spectra and spectral images is focused on characterization of the Martian surface and in particular identification of aqueous processes there.

  16. Preparation of pure calcium carbonate by mineral carbonation using industrial byproduct FGD gypsum

    Science.gov (United States)

    Song, K.; Kim, W.; Bang, J. H.; Park, S.; Jeon, C. W.

    2015-12-01

    Mineral carbonation is one of the geological approaches for the sequestration of anthropogenic CO2 gas. Its concept is based on the natural weathering processes in which silicate minerals containing divalent cations such as Ca or Mg are carbonated to CaCO3 or MgCO3 in the reaction with CO2gas. Raw materials for the mineral carbonation have been extended to various industrial solid wastes such as steel slag, ashes, or FGD (flue gas desulfurization) gypsum which are rich in divalent cations. These materials have economic advantages when they are produced in CO2 emission sites. Flue gas desulfurization (FGD) gypsum is such a byproduct obtained in at coal-fired power plants. Recently, we carried out a research on the direct mineral carbonation of FGD gypsum for CO2sequestration. It showed high carbonation reactivity under ambient conditions and the process can be described as follows: CaSO4·2H2O + CO2(g) + 2NH4OH(aq) → CaCO3(s) + (NH4)2SO4(aq) (1) At the early stage of the process, calcium carbonate (CaCO3) exists as a dissolved ion pair during the induction period. High-purity CaCO3 could be precipitated from dissolved calcium carbonate solution extracted during the induction period. The effect of experimental parameters on pure CaCO3 was evaluated: CO2 flow rate (1-3 L/min), ammonia content (4-12%), and solid-to-liquid (S/L) ratio (5-300 g/L). FE-SEM (field-emission scanning electron microscopy) and XRD (X-ray diffraction) study revealed that the precipitated CaCO3 was round-shaped vaterite crystals. The induction time was inversely proportional to the CO2 flow rate and the yield for pure CaCO3 increased with the ammonia content. The formation efficiency for pure CaCO3 decreased with S/L (solid/liquid) ratio. It was 90% (mol/mol) when the S/L ratio was 5 g/L. However, S/L ratio didn't affect the maximum solubility limit of dissolved CaCO3.

  17. Decomposition and Mineralization of Dimethyl Phthalate in an Aqueous Solution by Wet Oxidation

    Directory of Open Access Journals (Sweden)

    Dar-Ren Ji

    2015-01-01

    Full Text Available Dimethyl phthalate (DMP was treated via wet oxygen oxidation process (WOP. The decomposition efficiency ηDMP of DMP and mineralization efficiency ηTOC of total organic carbons were measured to evaluate the effects of operation parameters on the performance of WOP. The results revealed that reaction temperature T is the most affecting factor, with a higher T offering higher ηDMP and ηTOC as expected. The ηDMP increases as rotating speed increases from 300 to 500 rpm with stirring enhancement of gas liquid mass transfer. However, it exhibits reduction effect at 700 rpm due to purging of dissolved oxygen by overstirring. Regarding the effects of pressure PT, a higher PT provides more oxygen for the forward reaction with DMP, while overhigh PT increases the absorption of gaseous products such as CO2 and decomposes short-chain hydrocarbon fragments back into the solution thus hindering the forward reaction. For the tested PT of 2.41 to 3.45 MPa, the results indicated that 2.41 MPa is appropriate. A longer reaction time of course gives better performance. At 500 rpm, 483 K, 2.41 MPa, and 180 min, the ηDMP and ηTOC are 93 and 36%, respectively.

  18. Comparison of two electrolyte models for the carbon capture with aqueous ammonia

    DEFF Research Database (Denmark)

    Darde, Victor; Thomsen, Kaj; van Well, Willy J.M.;

    2012-01-01

    Post-combustion carbon capture is attracting much attention due to the fact that it can be retrofitted on existing coal power plants. Among the most interesting technologies is the one that employs aqueous ammonia solutions to absorb the generated carbon dioxide. The evaluation of such process...

  19. Temperature Sensitivity of Soil Organic Carbon Mineralization along an Elevation Gradient in the Wuyi Mountains, China

    OpenAIRE

    Guobing Wang; Yan Zhou; Xia Xu; Honghua Ruan; Jiashe Wang

    2013-01-01

    Soil organic carbon (SOC) actively participates in the global carbon (C) cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC) mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0-10 cm) from evergreen broad-leaf forest (EBF), coniferous forest (CF), sub-alpine dwarf forest (SDF), and alpine meadow (AM) along an elevational gradient in the Wuyi Mountai...

  20. The role of multivalent metal cations and organic complexing agents in bitumen-mineral interactions in aqueous solutions

    Science.gov (United States)

    Gan, Weibing

    A systematic investigation was carried out to study the interactions between bitumen (or hexadecane) and minerals (quartz, kaolinite and illite) in aqueous solutions containing multivalent metal cations Ca2+, Mg2+ and Fe2+/Fe3+, in the absence and presence of organic complexing agents (oxalic acid, EDTA and citric acid). A range of experimental techniques, including coagulation measurement, visualization of bitumen-mineral attachment, metal ion adsorption measurement, zeta potential measurement, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopic analyses, were employed in the investigation. Free energy changes of adsorption of metal cations on the minerals and bitumen were evaluated using the James & Healy thermodynamic model. Total interaction energies between the minerals and bitumen were calculated using classical DLVO theory. It was observed that while the tested minerals showed varying degrees of mutual-coagulation with bitumen (or hexadecane), the presence of the multivalent metal cations could prominently increase the mutual coagulation. It was also found that such enhancement of the mutual coagulation was only significant when the metal cations formed first-order hydroxyl complexes (such as CaOH +, MgOH+, etc.) or metal hydroxides (such as Fe(OH) 3, Mg(OH)2, etc.). Therefore, the increase of the bitumen-mineral mutual coagulation by the metal cations was strongly pH dependent. Organic complexing agents (oxalic acid, citric acid and EDTA) used in this study, citric acid in particular, significantly reduced or virtually eliminated the mutual coagulation between bitumen (or hexadecane) and minerals caused by metal cations Ca2+, Mg2+, Fe 2+ and Fe3+. Due to its ability to substantially lower the mutual coagulation between bitumen and mineral particles, citric acid was found the most effective in improving bitumen-mineral liberation in solutions containing the multivalent metal cations at pH 8--10. In small scale flotation experiments

  1. Arsenic(III) adsorption from aqueous solutions on novel carbon cryogel/ceria nanocomposite

    OpenAIRE

    Tamara Minović Arsić; Ana Kalijadis; Branko Matović; Milovan Stoiljković; Jelena Pantić; Jovan Jovanović; Rada Petrović; Bojan Jokić; Biljana Babić

    2016-01-01

    Carbon cryogel/ceria composite, with 10 wt.% of ceria, was synthesized by mixing of ceria and carbon cryogel (CC). The sample was characterized by field emission scanning electron microscopy, nitrogen adsorption and X-ray diffraction. The adsorption of arsenic(III) ions from aqueous solutions on carbon cryogel/ceria nanocomposite was studied as a function of time, solution pH and As(III) ion concentration. The results are correlated with previous investigations of adsorption mechanism of arse...

  2. HYDROPHOBIC AGGLOMERATION OF MINERAL FINES IN AQUEOUS SUSPENSIONS AND ITS APPLICATION IN FLOTATION: A REVIEW

    OpenAIRE

    BINGQIAO YANG; SHAOXIAN SONG

    2014-01-01

    Hydrophobic agglomeration is originated from the hydrophobic attraction between particles, which is essentially different from electrolyte coagulation and polymer flocculation. It is applied to mineral processing in floc-flotation process to improve the recovery of mineral fines. In this paper, the applications of this phenomenon in mineral fines were summarized, including the origin of hydrophobic agglomeration, the main factors affect hydrophobic agglomeration (particle hydrophobicity, shea...

  3. Mechanisms of aqueous wollastonite carbonation as a possible CO2 sequestration process

    International Nuclear Information System (INIS)

    The mechanisms of aqueous wollastonite carbonation as a possible carbon dioxide sequestration process were investigated experimentally by systematic variation of the reaction temperature, CO2 pressure, particle size, reaction time, liquid to solid ratio and agitation power. The carbonation reaction was observed to occur via the aqueous phase in two steps: (1) Ca leaching from the CaSiO3 matrix and (2) CaCO3 nucleation and growth. Leaching is hindered by a Ca-depleted silicate rim resulting from incongruent Ca-dissolution. Two temperature regimes were identified in the overall carbonation process. At temperatures below an optimum reaction temperature, the overall reaction rate is probably limited by the leaching rate of Ca. At higher temperatures, nucleation and growth of calcium carbonate is probably limiting the conversion, due to a reduced (bi)carbonate activity. The mechanisms for the aqueous carbonation of wollastonite were shown to be similar to those reported previously for an industrial residue and a Mg-silicate. The carbonation of wollastonite proceeds rapidly relative to Mg-silicates, with a maximum conversion in 15 min of 70% at 200C, 20 bar CO2 partial pressure and a particle size of <38 μm. The obtained insight in the reaction mechanisms enables the energetic and economic assessment of CO2 sequestration by wollastonite carbonation, which forms an essential next step in its further development

  4. A disconnect between O horizon and mineral soil carbon - Implications for soil C sequestration

    Science.gov (United States)

    Garten, Charles T., Jr.

    2009-03-01

    Changing inputs of carbon to soil is one means of potentially increasing carbon sequestration in soils for the purpose of mitigating projected increases in atmospheric CO 2 concentrations. The effect of manipulations of aboveground carbon input on soil carbon storage was tested in a temperate, deciduous forest in east Tennessee, USA. A 4.5-year experiment included exclusion of aboveground litterfall and supplemental litter additions (three times ambient) in an upland and a valley that differed in soil nitrogen availability. The estimated decomposition rate of the carbon stock in the O horizon was greater in the valley than in the upland due to higher litter quality (i.e., lower C/N ratios). Short-term litter exclusion or addition had no effect on carbon stock in the mineral soil, measured to a depth of 30 cm, or the partitioning of carbon in the mineral soil between particulate- and mineral-associated organic matter. A two-compartment model was used to interpret results from the field experiments. Field data and a sensitivity analysis of the model were consistent with little carbon transfer between the O horizon and the mineral soil. Increasing aboveground carbon input does not appear to be an effective means of promoting carbon sequestration in forest soil at the location of the present study because a disconnect exists in carbon dynamics between O horizon and mineral soil. Factors that directly increase inputs to belowground soil carbon, via roots, or reduce decomposition rates of organic matter are more likely to benefit efforts to increase carbon sequestration in forests where carbon dynamics in the O horizon are uncoupled from the mineral soil.

  5. Non-aqueous formation of the calcium carbonate polymorph vaterite: astrophysical implications

    CERN Document Server

    Day, Sarah J; Parker, Julia E; Evans, Aneurin

    2013-01-01

    We study the formation of calcium carbonate, through the solid-gas interaction of amorphous Ca-silicate with gaseous CO2, at elevated pressures, and link this to the possible presence of calcium carbonate in a number of circumstellar and planetary environments. We use in-situ synchrotron X-Ray powder diffraction to obtain detailed structural data pertaining to the formation of the crystalline calcium carbonate phase vaterite and its evolution with temperature. We found that the metastable calcium carbonate phase vaterite was formed alongside calcite, at elevated CO2 pressure, at room temperature and subsequently remained stable over a large range of temperature and pressure. We report the formation of the calcium carbonate mineral vaterite whilst attempting to simulate carbonate dust grain formation in astrophysical environments. This suggests that vaterite could be a mineral component of carbonate dust and also presents a possible method of formation for vaterite and its polymorphs on planetary surfaces.

  6. Some results from a study of carbon minerals by the thermal method

    Energy Technology Data Exchange (ETDEWEB)

    Otakuziyev, E.; Kasymov, A.K.; Miralimova, N.M.

    1979-01-01

    Using the optimum technique of thermal analysis in carbon-containing shales and hornfels of ancient deposits of the Kyzylkum and Zirabulak-Ziaetdinsk mountains, four groups are revealed of mineral form of carbon, corresponding to the kerite-oxykeriteanthraxolite-shungite-graphite series. Interpretation of the thermograms obtained shows the varying degree of metamorphism of the carbon-containing rock of the areas studied.

  7. Delineation of Magnesium-rich Ultramafic Rocks Available for Mineral Carbon Sequestration in the United States

    Science.gov (United States)

    Krevor, S.C.; Graves, C.R.; Van Gosen, B. S.; McCafferty, A.E.

    2009-01-01

    The 2005 Intergovernmental Panel on Climate Change report on Carbon Dioxide Capture and Storage suggested that a major gap in mineral carbon sequestration is locating the magnesium-silicate bedrock available to sequester CO2. It is generally known that silicate minerals with high concentrations of magnesium are suitable for mineral carbonation. However, no assessment has been made covering the entire United States detailing their geographical distribution and extent, or evaluating their potential for use in mineral carbonation. Researchers at Columbia University and the U.S. Geological Survey have developed a digital geologic database of ultramafic rocks in the continental United States. Data were compiled from varied-scale geologic maps of magnesium-silicate ultramafic rocks. These rock types are potentially suitable as source material for mineral carbon-dioxide sequestration. The focus of the national-scale map is entirely on suitable ultramafic rock types, which typically consist primarily of olivine and serpentine minerals. By combining the map with digital datasets that show non-mineable lands (such as urban areas and National Parks), estimates on potential depth of a surface mine, and the predicted reactivities of the mineral deposits, one can begin to estimate the capacity for CO2 mineral sequestration within the United States. ?? 2009 Elsevier Ltd. All rights reserved.

  8. Refinements of water parameters for molecular dynamics: Simulations of adsorption at the clay mineral/aqueous solution interface

    DEFF Research Database (Denmark)

    Schäfer, L.; Yu, C.; Teppen, B.J.;

    1999-01-01

    In the context of a long-term program involving molecular dynamics simulations of adsorption phenomena at the clay mineral/aqueous solution interface, we are testing the viability of combining a force field that we developed specificially for clays with other, independently derived potential...... parameters for molecular species which are important in clay adsorption. For the current study the importance of variations in the potential parameters of water were investigated and polarization effects on oxygen studied as a function of intermolecular interactions. For this purpose ab initio MP2/6-311GG...... hydrated clays is described....

  9. Mineral carbonation of phosphogypsum waste for production of useful carbonate and sulfate salts

    Directory of Open Access Journals (Sweden)

    Hannu-Petteri eMattila

    2015-11-01

    Full Text Available Phosphogypsum (CaSO4·2H2O waste is produced in large amounts during phosphoric acid (H3PO4 production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred Mt of carbon dioxide (CO2. For example, when gypsum is converted to ammonium sulfate ((NH42SO4 with ammonia (NH3 and CO2, also solid calcium carbonate (CaCO3 is generated. The ammonium sulfate can be utilized as a fertilizer or in other mineral carbonation processes that use magnesium silicate-based rock as feedstock, while calcium carbonate has various uses as e.g. filler material. The reaction extent of the described process was studied by thermodynamic modeling and experimentally as a function of reactant concentrations and temperature. Other essential properties such as purity and quality of the solid products are also followed. Conversion efficiencies of >95% calcium from phosphogypsum to calcium carbonate are obtained. Scalenohedral, rhombohedral and prismatic calcite particles can be produced, though the precipitates contain certain contaminants such as rare earth metals and sulfur from the gypsum. A reverse osmosis membrane cartridge is also tested as an alternative and energy-efficient method of concentrating the ammonium sulfate salt solution instead of the traditional evaporation of the process solution.

  10. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    OpenAIRE

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B; Henry, Drew

    2015-01-01

    “Clumped-isotope” thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of ^(13)C and ^(18)O isotopes bound to each other within carbonate minerals in ^(13)C^(18)O^(16)O_2^(2−) groups (heavy isotope “clumps”). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solutio...

  11. Adsorption of methylene blue and Congo red from aqueous solution by activated carbon and carbon nanotubes.

    Science.gov (United States)

    Szlachta, M; Wójtowicz, P

    2013-01-01

    This study was conducted to determine the adsorption removal of dyes by powdered activated carbon (PAC, Norit) and multi-walled carbon nanotubes (MWCNTs, Chinese Academy of Science) from an aqueous solution. Methylene blue (MB) and Congo red (CR) were selected as model compounds. The adsorbents tested have a high surface area (PAC 835 m(2)/g, MWCNTs 358 m(2)/g) and a well-developed porous structure which enabled the effective treatment of dye-contaminated waters and wastewaters. To evaluate the capacity of PAC and MWCNTs to adsorb dyes, a series of batch adsorption experiments was performed. Both adsorbents exhibited a high adsorptive capacity for MB and CR, and equilibrium data fitted well with the Langmuir model, with the maximum adsorption capacity up to 400 mg/g for MB and 500 mg/g for CR. The separation factor, RL, revealed the favorable nature of the adsorption process under experimental conditions. The kinetics of adsorption was studied at various initial dye concentrations and solution temperatures. The pseudo-second-order model was used for determining the adsorption kinetics of MB and CR. The data obtained show that adsorption of both dyes was rapid in the initial stage and followed by slower processing to reach the plateau. The uptake of dyes increased with contact time, irrespective of their initial concentration and solution temperature. However, changes in the solution temperature did not significantly influence dye removal. PMID:24292474

  12. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    International Nuclear Information System (INIS)

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA–MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species. (papers)

  13. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    Science.gov (United States)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  14. Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

    Science.gov (United States)

    Ruiz, B.; Cabrita, I.; Mestre, A. S.; Parra, J. B.; Pires, J.; Carvalho, A. P.; Ania, C. O.

    2010-06-01

    The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.

  15. Thermal properties of carbon black aqueous nanofluids for solar absorption

    Directory of Open Access Journals (Sweden)

    Han Dongxiao

    2011-01-01

    Full Text Available Abstract In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency.

  16. Roles of Mineralogical Phases in Aqueous Carbonation of Steelmaking Slag

    Directory of Open Access Journals (Sweden)

    Huining Zhang

    2016-05-01

    Full Text Available Mineralogical phases of steelmaking slags have significant influences on the carbonation of the slags. In this paper, the effects of temperature and reaction time on the conversion of calcium-related phases and the carbonation degree of a slag sample were studied. The experimental conditions were a liquid-to-solid ratio of 20 mL/g, a carbon dioxide flow rate of 1 L/min and a slag particle size of 38–75 μm. The results show that the optimum carbonation temperature and reaction time are 60 °C and 90 min, respectively, and calcite phase content is about 26.78% while the conversion rates of Ca3Al2O6, CaSiO3, Ca2SiO4 and free CaO are about 40%, 42.46%, 51% and 100%, respectively, and the carbon dioxide sequestration efficiency is about 170 g/kg slag.

  17. Research on determining organic carbon in rock and mineral samples by gas chromatography

    International Nuclear Information System (INIS)

    The authors introduce results of research on transformation mechanism, temperature and time of organic carbon during analysis of rock and mineral samples by gas chromatography, as well as conditions for eliminating carbonate constituent that may produce carbon dioxide gas. The research has solved the problem of connecting the chemical processing and instrument determination. The newly-established method is characterized by high sensitivity, good exactitude, simple and fast operation, and may be applied to the determination of organic carbon in rock, mineral, as well as sediment samples

  18. Heterogeneous Photocatalytic Mineralization of Chlorobenzene by Paratungstate-loaded Titania Catalysts in an Aqueous Medium

    Institute of Scientific and Technical Information of China (English)

    YUE Bin; JIANG Lei; HU Chang-wen; CHEN Jian-min; HE He-yong

    2005-01-01

    Paratungstate-loaded titania catalysts were prepared via the addition of a series of aqueous solutions of paratungstate(denoted as W7) into an isopropanol solution of Ti[OCH(CH3)2]4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstate-loaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400 ℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.

  19. Sorption of a phenols mixture in aqueous solution with activated carbon; Sorcion de una mezcla de fenoles en solucion acuosa con carbon activado

    Energy Technology Data Exchange (ETDEWEB)

    Mejia M, D

    2004-07-01

    The constant population growth and the quick industrialization have caused severe damages to our natural aquifer resources for a great variety of organic and inorganic pollutants. Among these they are those phenol compounds that are highly toxic, resistant (to the degradation chemistry) and poorly biodegradable. The phenolic compounds is used in a great variety of industries, like it is the production of resins, nylon, plastifiers, anti-oxidants, oil additives, drugs, pesticides, colorants, explosives, disinfectants and others. The disseminated discharges or effluents coming from the industrial processes toward lakes and rivers are causing a growing adverse effect in the environment, as well as a risk for the health. Numerous studies exist on the phenols removal and phenols substituted for very varied techniques, among them they are the adsorption in activated carbon. This finishes it has been used successfully for the treatment of residual waters municipal and industrial and of drinking waters and it is considered as the best technique available to eliminate organic compounds not biodegradable and toxic present in aqueous solution (US EPA, 1991). However a little information exists on studies carried out in aqueous systems with more of a phenolic compound. The activated carbon is broadly used as adsorbent due to its superficial properties in the so much treatment of water as of aqueous wastes, adsorbent for the removal of organic pollutants. The main objective of this work is the adsorption of a aqueous mixture of phenol-4 chloro phenol of different concentrations in activated carbon of mineral origin of different meshes and to diminish with it their presence in water. The experiments were carried out for lots, in normal conditions of temperature and pressure. The experimental results show that the removal capacity depends so much of the superficial properties of the sorbent like of the physical properties and chemical of the sorbate. The isotherms were carried

  20. Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

    Science.gov (United States)

    Ehlmann, B. L.; Bish, D. L.; Ruff, S. W.; Mustard, J. F.

    2012-10-01

    We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars.

  1. Metallic and semiconducting carbon nanotubes separation using an aqueous two-phase separation technique: a review

    Science.gov (United States)

    Tang, Malcolm S. Y.; Ng, Eng-Poh; Juan, Joon Ching; Ooi, Chien Wei; Ling, Tau Chuan; Woon, Kai Lin; Loke Show, Pau

    2016-08-01

    It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.

  2. Experimental measurement and modeling of the rate of absorption of carbon dioxide by aqueous ammonia

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J.M.; Fosbøl, Philip Loldrup;

    2011-01-01

    In this work, the rate of absorption of carbon dioxide by aqueous ammonia solvent has been studied by applying a newly built wetted wall column. The absorption rate in aqueous ammonia was measured at temperatures from 279 to 304K for 1 to 10wt% aqueous ammonia with loadings varying from 0 to 0.8mol......CO2/molNH3. The absorption rate in 30wt% aqueous mono-ethanolamine (MEA) was measured at 294 and 314K with loadings varying from 0 to 0.4 as comparison.It was found that at 304K, the rate of absorption of carbon dioxide by 10wt% NH3 solvent was comparable to the rates for 30wt% MEA at 294 and 314K (a.......The rate of absorption decreases strongly with decreasing ammonia concentrations and increasing CO2 loadings.The rate of absorption of carbon dioxide by aqueous ammonia solvent was modeled using the measurements of the unloaded solutions and the zwitter-ion mechanism. The model could successfully predict...

  3. Integrated Experimental and Modeling Studies of Mineral Carbonation as a Mechanism for Permanent Carbon Sequestration in Mafic/Ultramafic Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhengrong [Yale Univ., New Haven, CT (United States); Qiu, Lin [Yale Univ., New Haven, CT (United States); Zhang, Shuang [Yale Univ., New Haven, CT (United States); Bolton, Edward [Yale Univ., New Haven, CT (United States); Bercovici, David [Yale Univ., New Haven, CT (United States); Ague, Jay [Yale Univ., New Haven, CT (United States); Karato, Shun-Ichiro [Yale Univ., New Haven, CT (United States); Oristaglio, Michael [Yale Univ., New Haven, CT (United States); Zhu, Wen-Iu [Univ. of Maryland, College Park, MD (United States); Lisabeth, Harry [Univ. of Maryland, College Park, MD (United States); Johnson, Kevin [Univ. of Hawaii, Honolulu, HI (United States)

    2014-09-30

    A program of laboratory experiments, modeling and fieldwork was carried out at Yale University, University of Maryland, and University of Hawai‘i, under a DOE Award (DE-FE0004375) to study mineral carbonation as a practical method of geologic carbon sequestration. Mineral carbonation, also called carbon mineralization, is the conversion of (fluid) carbon dioxide into (solid) carbonate minerals in rocks, by way of naturally occurring chemical reactions. Mafic and ultramafic rocks, such as volcanic basalt, are natural candidates for carbonation, because the magnesium and iron silicate minerals in these rocks react with brines of dissolved carbon dioxide to form carbonate minerals. By trapping carbon dioxide (CO2) underground as a constituent of solid rock, carbonation of natural basalt formations would be a secure method of sequestering CO2 captured at power plants in efforts to mitigate climate change. Geochemical laboratory experiments at Yale, carried out in a batch reactor at 200°C and 150 bar (15 MPa), studied carbonation of the olivine mineral forsterite (Mg2SiO4) reacting with CO2 brines in the form of sodium bicarbonate (NaHCO3) solutions. The main carbonation product in these reactions is the carbonate mineral magnesite (MgCO3). A series of 32 runs varied the reaction time, the reactive surface area of olivine grains and powders, the concentration of the reacting fluid, and the starting ratio of fluid to olivine mass. These experiments were the first to study the rate of olivine carbonation under passive conditions approaching equilibrium. The results show that, in a simple batch reaction, olivine carbonation is fastest during the first 24 hours and then slows significantly and even reverses. A natural measure of the extent of carbonation is a quantity called the carbonation fraction, which compares the amount of carbon removed from solution, during a run, to the maximum amount

  4. Carbon-mineral adsorbents prepared by pyrolysis of waste materials in the presence of tetrachloromethane.

    Science.gov (United States)

    Leboda, Roman; Charmas, Barbara; Skubiszewska-Zieba, Jadwiga; Chodorowski, Stanislaw; Oleszczuk, Patryk; Gun'ko, Vladimir M; Pokrovskiy, Valery A

    2005-04-01

    Natural bentonite spent in the process of plant oil bleaching was used as an initial material for preparation of carbon-mineral adsorbents. The spent bleaching earth was treated using four procedures: T (thermal treatment); H (hydrothermal treatment); C (thermal treatment with addition of CCl4 vapor); M (modification of porous structure). Raw bentonite, RB (raw bleaching earth), and carbon materials prepared using plant oil were compared. The physicochemical characteristics of the adsorbents were determined using different methods: nitrogen adsorption/desorption, XRD, TEM, and MS-TPD. Carbon-mineral adsorbents contain from 5.23 to 19.92% C (w/w) and carbon adsorbents include from 84.2 to 91.18% C (w/w). Parallel processes of organic substance carbonization, porous structure modification, sublimation or evaporation of metal chlorides, and removal of hydrogen chloride take place during pyrolysis of waste mineral materials in the CCl4 atmosphere. PMID:15752782

  5. Separation of Th from aqueous solutions using activated carbon

    International Nuclear Information System (INIS)

    Since the last century, thorium has been extensively used in a variety of applications. These applications produce various gaseous, liquid and solid wastes containing isotopes of thorium. Liquid wastes are freed into the surface or the underground waters of mines. Solid and liquid wastes are also produced during nuclear fuel production. Direct toxicity of thorium is low due to its stability at ambient temperatures; however thorium fine powder is self-ignitable to thorium oxide. When thorium nitrate enters living organisms it is mainly localized in liver, spleen and marrow and it precipitates in a hydroxide form. Investigations concerning the removal or minimization of the thorium concentration in the waste waters are of considerable importance environmental point of view. Adsorption is an important technique in separation and purification processes. Among many types of adsorbent materials, activated carbons are the most widely used, because of their large adsorptive capacity and low cost. Activated carbons are unique adsorbents because of their extended surface area, microporous structure, high adsorption capacity and high degree of surface reactivity. Separation and purification processes based on adsorption technique are also important in nuclear industry where activated carbon is often used for the separation of metal ions from solutions, due to its selective adsorption, high radiation stability and high purity. The activated carbons used in this study were prepared by the chemical activation of acrylic fiber. The chemical composition of acrylic fiber is a copolymer of acrylonitrile-vinyl acetate is called also poliacrylonitryl fiber. The effects of carbonization conditions resulting activated carbon were examined. Precursor/activating agent (KOH and ZnCl2) ratio and carbonization temperature were investigated for the preparation of adsorbent. Adsorption experiments were carried out by a batch technique. The adsorption of thorium was studied as a function of

  6. Mineralization of carbon dioxide sequestered in volcanogenic sandstone reservoir rocks

    OpenAIRE

    Zhang, Shuo

    2014-01-01

    We proposed to use volcanogenic sandstones for CO2 sequestration. Such sandstones with a relatively high percentage of volcanic rock fragments (VRF) could be a promising target for CO2 sequestration in that they have a sufficient percentage of reactive minerals to allow substantial mineralization of injected scCO2, which provides the most secure form of CO2 storage, but can also be porous and permeable enough to allow injection at acceptable rates. The limitation in using volcanogenic sandsto...

  7. Performance of multiwall carbon nanotubes for removal phenol from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Mohamad Hadi Dehghani

    2013-05-01

    Conclusion: It is concluded that carbon nanotubes being effective in a wide range of pH, short time to reach equilibrium and the absence of competing ions on the absorption process can be used effectively in removing phenol from aqueous solution.

  8. Temperature sensitivity of soil organic carbon mineralization along an elevation gradient in the Wuyi Mountains, China.

    Directory of Open Access Journals (Sweden)

    Guobing Wang

    Full Text Available Soil organic carbon (SOC actively participates in the global carbon (C cycle. Despite much research, however, our understanding of the temperature sensitivity of soil organic carbon (SOC mineralization is still very limited. To investigate the responses of SOC mineralization to temperature, we sampled surface soils (0-10 cm from evergreen broad-leaf forest (EBF, coniferous forest (CF, sub-alpine dwarf forest (SDF, and alpine meadow (AM along an elevational gradient in the Wuyi Mountains, China. The soil samples were incubated at 5, 15, 25, and 35°C with constant soil moisture for 360 days. The temperature sensitivity of SOC mineralization (Q(10 was calculated by comparing the time needed to mineralize the same amount of C at any two adjacent incubation temperatures. Results showed that the rates of SOC mineralization and the cumulative SOC mineralized during the entire incubation significantly increased with increasing incubation temperatures across the four sites. With the increasing extent of SOC being mineralized (increasing incubation time, the Q(10 values increased. Moreover, we found that both the elevational gradient and incubation temperature intervals significantly impacted Q(10 values. Q(10 values of the labile and recalcitrant organic C linearly increased with elevation. For the 5-15, 15-25, and 25-35°C intervals, surprisingly, the overall Q(10 values for the labile C did not decrease as the recalcitrant C did. Generally, our results suggest that subtropical forest soils may release more carbon than expected in a warmer climate.

  9. Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization.

    Science.gov (United States)

    Ren, Dongni; Li, Zhuo; Gao, Yonghua; Feng, Qingling

    2010-10-01

    Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH2 and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH2 and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different. PMID:20844320

  10. Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Ren Dongni; Li Zhuo; Gao Yonghua; Feng Qingling, E-mail: biomater@mail.tsinghua.edu.c [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2010-10-01

    Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH{sub 2} and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH{sub 2} and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different.

  11. Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization

    International Nuclear Information System (INIS)

    Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH2 and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH2 and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different.

  12. Influence of the particle size of activated mineral carbon on the phenol and chlorophenol adsorption; Influencia del tamano de particula de carbon mineral activado sobre la adsorcion de fenol y clorofenol

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, A

    2001-07-01

    Water pollution by phenolic compounds is a problem that requires a solution since these phenolic compounds are not completely biodegradable, they accumulate through the food chains and they are quite toxic when enter in contact with living organisms. In human beings, ingestion or contact of the skin with this type of compounds produces irritation and damages mainly to the liver and kidneys. In fact, the Environmental Protection Agency of the United States (EPA assigned nine phenolic compounds among the 275 most toxic substances in 1991. Phenols are found in wastewater from agriculture and industry, because phenolic compounds are used as pesticides and in diverse industrial activities. The treatment of this type of water is not simple because they are generally composed of a mixture of residuals with different chemical nature A useful method for the removal of phenols is the adsorption by activated carbon, since this material has a great surface area and it can be regenerated. The adsorption process depends, among other factors, on the activated carbon characteristics. When they are modified, their capacity to remove pollutants from the water changes. The effect of activated carbon particle size on the removal of phenolic compounds has not been completely studied. Therefore, the aim of this work was to determine the influence of the mineral activated carbon particle size on the phenol and 4-chloro phenol adsorption in aqueous solution, on adsorption column system. The results of the present work indicate that the mineral activated carbon particle size has a very important influence on the adsorption of phenol and 4-chloro phenol. When the particles were smaller, the retention quantities of phenol and 4-chloro phenol increased. This behavior was related to the particle characteristics of the mineral activated carbon such as surface area and pore volume, while other factors such as elementary composition of the activated carbon did not influence the adsorption process

  13. Molecular Simulations of the Diffusion of Uranyl Carbonate Species in Nanosized Mineral Fractures

    Science.gov (United States)

    Kerisit, S.; Liu, C.

    2010-12-01

    water and that of the electrolyte ions differ significantly from those in bulk aqueous solutions. We will then present MD simulations of the diffusion of a series of alkaline-earth uranyl carbonate species in aqueous solutions [7]. The MD simulations show that the alkaline-earth uranyl carbonate complexes have distinct water exchange dynamics, which could lead to different reactivities. Finally, we will present recent results on the diffusion and adsorption of uranyl carbonate species in intragrain micropores, modeled with the feldspar-water interfaces mentioned in the above, to help interpret the diffusion behavior of uranium in contaminated sediments. [1] Liu C. et al. Geochim. Cosmochim. Acta 68 4519 (2004) [2] McKinley J. P. et al. Geochim. Cosmochim. Acta 70 1873 (2006) [3] Liu C. et al. Water Resour. Res. 42 W12420 (2006) [4] Ilton E. S. et al. Environ. Sci. Technol. 42 1565 (2009) [5] Kerisit S. et al. Geochim. Cosmochim. Acta 72 1481 (2008) [6] Kerisit S. and Liu C. Environ. Sci. Technol. 43 777 (2009) [7] Kerisit S. and Liu C. Geochim. Cosmochim. Acta 74 4937 (2010)

  14. Sugars as the optimal biosynthetic carbon substrate of aqueous life throughout the universe

    Science.gov (United States)

    Weber, A. L.

    2000-01-01

    Our previous analysis of the energetics of metabolism showed that both the biosynthesis of amino acids and lipids from sugars, and the fermentation of organic substrates, were energetically driven by electron transfer reactions resulting in carbon redox disproportionation (Weber, 1997). Redox disproportionation--the spontaneous (energetically favorable) direction of carbon group transformation in biosynthesis--is brought about and driven by the energetically downhill transfer of electron pairs from more oxidized carbon groups (with lower half-cell reduction potentials) to more reduced carbon groups (with higher half-cell reduction potentials). In this report, we compare the redox and kinetic properties of carbon groups in order to evaluate the relative biosynthetic capability of organic substrates, and to identify the optimal biosubstrate. This analysis revealed that sugars (monocarbonyl alditols) are the optimal biosynthetic substrate because they contain the maximum number of biosynthetically useful high energy electrons/carbon atom while still containing a single carbonyl group needed to kinetically facilitate their conversion to useful biosynthetic intermediates. This conclusion applies to aqueous life throughout the Universe because it is based on invariant aqueous carbon chemistry--primarily, the universal reduction potentials of carbon groups.

  15. Nanoporous carbon synthesized from sol-gel template for adsorbing gibberellic acid in aqueous solution

    International Nuclear Information System (INIS)

    A novel method, based on dynamic carbonization and silica template formed by sol-gel, was developed to prepare nanoporous carbon materials with tailored pore structures. The effects of the sol-gel reaction and carbonization process on the final nanoporous carbon product were investigated by pore features such as specific surface area, the total pore volume, and pore size distribution, which were systemically characterized by iodine index, transmission electron microscopy, and nitrogen adsorption. The experimental results indicate that the pore structures of the prepared nanoporous carbon are tunable on the nano-scale by controlling the preparation process in the proposed method. The nanoporous carbon prepared under the optimal conditions has a high total pore volume of 1.26 cm3/g, a large specific surface area of 1744 m2/g, and a maximal adsorption capacity of 9.2 mg/g to gibberellic acid in aqueous solution, which is nearly 6 times that of commercial activated carbon. Highlights: → Silica formed by sol-gel as template for nanoporous carbon preparation. → Pore structures are tunable on the nano-scale. → High total pore volume and large specific surface developing. → Adsorption of gibberellic acid in aqueous solution carrying out.

  16. The extent of carbon mineralization in boreal soils controls compositional changes

    Science.gov (United States)

    Mercier Quideau, S.; Oh, S.; Paré, D.

    2013-12-01

    Almost twenty percent of global carbon stocks in vegetation and soil are found in boreal soils, making them the largest terrestrial carbon storehouse in the world. Yet, despite their importance in the global carbon budget, very little is known about the exact nature and decomposition pathways of organic matter in these soils. The overall objective of this study was to examine the effects of vegetation and disturbance (fire and harvest) on: 1) soil organic matter composition, and 2) decomposition-induced changes in composition from a range of representative boreal forest and peatland ecosystems. Forest floor and peat samples (0-10 cm) were obtained from 17 sites along an east-west transect from New Brunswick to British Columbia, Canada. Carbon mineralization rates were measured during a 1-year laboratory incubation at 10 °C. Carbon chemistry in pre- and post-incubation samples was characterized by solid-state ramped-cross-polarization (RAMP-CP) 13C nuclear magnetic resonance (NMR). The percentage of carbon mineralized during incubation ranged from 1 to 24%, and corresponded to significant increases in aromatic, phenolic, and carbonyl carbons. As expected, significant differences in carbon composition pre-incubation were found among vegetation types regardless of disturbance and sampling location. May be more interestingly, comparable differences among samples persisted post-incubation. In addition, decomposition-induced changes in carbon chemistry significantly differed among vegetation types. Samples from Jack pine and Douglas fir stands, which experienced the highest carbon mineralization, also showed the greatest increase in aromatic, phenolic, and carbonyl carbons. Overall, changes in carbon chemistry were significantly correlated to the percentage of carbon mineralized; i.e., the extent of decomposition that the samples underwent.

  17. Aqueous alteration of potassium-bearing aluminosilicate minerals: from mechanism to processing

    OpenAIRE

    Skorina, Taisiya; Allanore, Antoine

    2014-01-01

    The anticipated increase in demand for potassium fertilizers and alumina from developing nations experiencing a high-rate of population growth brings a global sustainability concern. Most of these countries do not have economically viable resources for both commodities; and the environmental footprint of existing technologies may compromise local ecosystems. Alternatives, both in terms of resources and extraction technologies, are therefore needed. Aqueous alteration of potassium-bearing alum...

  18. Immobilization of aqueous radioactive cesium wastes by conversion to aluminosilicate minerals

    International Nuclear Information System (INIS)

    Radioactive cesium (primarily 137Cs) is a major toxic constituent of liquid wastes from nuclear fuel processing plants. Because of the long half-life, highly penetrating radiation, and mobility of 137Cs, it is necessary to convert wastes containing this radioisotope into a solid form which will prevent movement to the biosphere during long-term storage. A method for converting cesium wastes to solid, highly insoluble, thermally stable aluminosilicate minerals is described. Aluminum silicate clays (bentonite, kaolin, or pyrophyllite) or hydrous aluminosilicate gels are reacted with basic waste solutions to form pollucite, cesium zeolite (Cs-D), Cs-F, cancrinite, or nepheline. Cesium is trapped in the aluminosilicate crystal lattice of the mineral and is permanently immobilized. The identity of the mineral product is dependent on the waste composition and the SiO2/Al2O3 ratio of the clay or gel. The stoichiometry and kinetics of mineral formation reactions are described. The products are evaluated with respect to leachability, thermal stability, and crystal morphology. (U.S.)

  19. Decolorization and mineralization of Allura Red AC aqueous solutions by electrochemical advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Thiam, Abdoulaye; Sirés, Ignasi; Garrido, José A.; Rodríguez, Rosa M.; Brillas, Enric, E-mail: brillas@ub.edu

    2015-06-15

    Highlights: • Quicker degradation of Allura Red AC in the order EO-H{sub 2}O{sub 2} < EF < PEF with Pt or BDD anode. • Almost total mineralization achieved by the most powerful PEF process with BDD. • Similar decolorization and mineralization rate in SO{sub 4}{sup 2−}, ClO{sub 4}{sup −} and NO{sub 3}{sup −} media. • In Cl{sup −} medium, only slightly larger decolorization rate but strong inhibition of mineralization. • Identification of aromatic products, carboxylic acids and released NH{sub 4}{sup +}, NO{sub 3}{sup −} and SO{sub 4}{sup 2−} ions. - Abstract: The decolorization and mineralization of solutions containing 230 mg L{sup −1} of the food azo dye Allura Red AC at pH 3.0 have been studied upon treatment by electrochemical oxidation with electrogenerated H{sub 2}O{sub 2} (EO-H{sub 2}O{sub 2}), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed with a stirred tank reactor containing a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode to generate H{sub 2}O{sub 2}. The main oxidants were hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between H{sub 2}O{sub 2} and added Fe{sup 2+}. The oxidation ability increased in the sequence EO-H{sub 2}O{sub 2} < EF < PEF and faster degradation was always obtained using BDD. PEF process with BDD yielded almost total mineralization following similar trends in SO{sub 4}{sup 2−}, ClO{sub 4}{sup −} and NO{sub 3}{sup −} media, whereas in Cl{sup −} medium, mineralization was inhibited by the formation of recalcitrant chloroderivatives. GC–MS analysis confirmed the cleavage of the −N=N− bond with formation of two main aromatics in SO{sub 4}{sup 2−} medium and three chloroaromatics in Cl{sup −} solutions. The effective oxidation of final oxalic and oxamic acids by BDD along with the photolysis of Fe(III)-oxalate species by UVA light accounted for the superiority of PEF with BDD. NH{sub 4

  20. Decolorization and mineralization of Allura Red AC aqueous solutions by electrochemical advanced oxidation processes

    International Nuclear Information System (INIS)

    Highlights: • Quicker degradation of Allura Red AC in the order EO-H2O2 < EF < PEF with Pt or BDD anode. • Almost total mineralization achieved by the most powerful PEF process with BDD. • Similar decolorization and mineralization rate in SO42−, ClO4− and NO3− media. • In Cl− medium, only slightly larger decolorization rate but strong inhibition of mineralization. • Identification of aromatic products, carboxylic acids and released NH4+, NO3− and SO42− ions. - Abstract: The decolorization and mineralization of solutions containing 230 mg L−1 of the food azo dye Allura Red AC at pH 3.0 have been studied upon treatment by electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed with a stirred tank reactor containing a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode to generate H2O2. The main oxidants were hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between H2O2 and added Fe2+. The oxidation ability increased in the sequence EO-H2O2 < EF < PEF and faster degradation was always obtained using BDD. PEF process with BDD yielded almost total mineralization following similar trends in SO42−, ClO4− and NO3− media, whereas in Cl− medium, mineralization was inhibited by the formation of recalcitrant chloroderivatives. GC–MS analysis confirmed the cleavage of the −N=N− bond with formation of two main aromatics in SO42− medium and three chloroaromatics in Cl− solutions. The effective oxidation of final oxalic and oxamic acids by BDD along with the photolysis of Fe(III)-oxalate species by UVA light accounted for the superiority of PEF with BDD. NH4+, NO3− and SO42− ions were released during the mineralization

  1. Formation of isomers of anionic hemiesters of sugars and carbonic acid in aqueous medium.

    Science.gov (United States)

    Dos Santos, Vagner B; Vidal, Denis T R; Francisco, Kelliton J M; Ducati, Lucas C; do Lago, Claudimir L

    2016-06-16

    Hemiesters of carbonic acid can be freely formed in aqueous media containing HCO3(-)/CO2 and mono- or poly-hydroxy compounds. Herein, (13)C NMR spectroscopy was used to identify isomers formed in aqueous solutions of glycerol (a prototype compound) and seven carbohydrates, as well as to estimate the equilibrium constant of formation (Keq). Although both isomers are formed, glycerol 1-carbonate corresponds to 90% of the product. While fructose and ribose form an indistinct mixture of isomers, the anomers of d-glucopyranose 6-carbonate correspond to 74% of the eight isomers of glucose carbonate that were detected. The values of Keq for the disaccharides sucrose (4.3) and maltose (4.2) are about twice the values for the monosaccharides glucose (2.0) and fructose (2.3). Ribose (Keq = 0.89)-the only sugar without a significant concentration of a species containing a -CH2OH group in an aqueous solution-resulted in the smallest Keq. On the basis of the Keq value and the concentrations of HCO3(-) and glucose in blood, one can anticipate a concentration of 2-4 µmol L(-1) for glucose 6-carbonate, which corresponds to ca. of 10% of its phosphate counterpart (glucose 6-phosphate). PMID:27111726

  2. Kinetics of carbon dioxide removal by aqueous diamines

    Energy Technology Data Exchange (ETDEWEB)

    Bindwal, A.B.; Vaidya, P.D.; Kenig, E.Y. [Inst. of Chemical Technology, Bombay (India). Dept. of Chemical Engineering

    2011-05-01

    Because of the presence of one or more primary or secondary amino groups, solvents containing diamines have a good potential for CO{sub 2} capture. In the present work, the CO{sub 2} reactions with two diamines, namely N-(2-aminoethyl)ethanolamine (AEEA) and piperazine (PZ), in aqueous solutions are investigated using a stirred-cell reactor. The reaction pathways are described using the zwitterion and the termolecular mechanism. Solution densities and viscosities are measured. The investigated reactions belong to the fast reaction regime systems. It is found that the CO{sub 2} reaction with AEEA is of the second order with respect to AEEA within the temperature range 298-308 K and amine concentration range 1.5-3 kmol/m{sup 3}. At 303 K. the reaction rate constant equals 8530 m{sup 6}/(kmol{sup 2} s). The value of the second-order rate constant for the CO{sub 2} reaction with PZ is found to be 25.800 m{sup 3}/(kmol s) at 303 K.

  3. Electrical double layer at the mineral-aqueous solution interface as probed by XPS with fast-frozen samples

    International Nuclear Information System (INIS)

    The electrical double layer (EDL) at the mineral-aqueous solution interface is a typical example of intrinsic charging effects. As a key feature of the interface, the EDL determines its chemical composition and electrical field. The ability of the XPS technique to probe this phenomenon on fast-frozen samples is presented. It allows the quantification of counter-ions and the direct observation of interface chemical processes, such as ion pairing, specific adsorption and ligand exchange reactions. It is also shown that binding energy shifts arising due to water removal provide an experimental possibility to estimate surface potentials and their distribution within the EDL. Future directions and perspectives of the technique are shortly discussed.

  4. Ab initio prediction of equilibrium boron isotope fractionation between minerals and aqueous fluids at high P and T

    CERN Document Server

    Kowalski, Piotr M; Jahn, Sandro

    2012-01-01

    Over the last decade experimental studies have shown a large B isotope fractionation between materials carrying boron incorporated in trigonally and tetrahedrally coordinated sites, but the mechanisms responsible for producing the observed isotopic signatures are poorly known. In order to understand the boron isotope fractionation processes and to obtain a better interpretation of the experimental data and isotopic signatures observed in natural samples, we use first principles calculations based on density functional theory in conjunction with ab initio molecular dynamics and a new pseudofrequency analysis method to investigate the B isotope fractionation between B-bearing minerals (such as tourmaline and micas) and aqueous fluids containing H_3BO_3 and H_4BO_4- species. We confirm the experimental finding that the isotope fractionation is mainly driven by the coordination of the fractionating boron atoms and have found in addition that the strength of the produced isotopic signature is strongly correlated w...

  5. Physicochemical characterization of the retardation of aqueous Cs+ ions by natural kaolinite and clinoptilolite minerals

    OpenAIRE

    Shahwan, Talal; Akar, Dilek; Eroğlu, Ahmet E.

    2005-01-01

    The aim of this study was to carry out kinetic, thermodynamic, and surface characterization of the sorption of Cs+ ions on natural minerals of kaolinite and clinoptilolite. The results showed that sorption followed pseudo-second-order kinetics. The activation energies were 9.5 and 13.9 kJ/mol for Cs+ sorption on kaolinite and clinoptilolite, respectively. Experiments performed at four different initial concentrations of the ion revealed that the percentage sorption of Cs+ on clinoptilolite ra...

  6. Physicochemical characterization of the retardation of aqueous Cs+ ions by natural kaolinite and clinoptilolite minerals.

    Science.gov (United States)

    Shahwan, T; Akar, D; Eroğlu, A E

    2005-05-01

    The aim of this study was to carry out kinetic, thermodynamic, and surface characterization of the sorption of Cs+ ions on natural minerals of kaolinite and clinoptilolite. The results showed that sorption followed pseudo-second-order kinetics. The activation energies were 9.5 and 13.9 kJ/mol for Cs+ sorption on kaolinite and clinoptilolite, respectively. Experiments performed at four different initial concentrations of the ion revealed that the percentage sorption of Cs+ on clinoptilolite ranged from 90 to 95, compared to 28 to 40 for the kaolinite case. At the end of a 1 week period, the percentage of Cs+ desorption from clinoptilolite did not exceed 7%, while it amounted to more than 30% in kaolinite, indicating more stable fixation by clinoptilolite. The sorption data were best described using Freundlich and D-R isotherm models. Sorption showed spontaneous and exothermic behavior on both minerals, with deltaH(0) being -6.3 and -11.4 kJ/mol for Cs+ uptake by kaolinite and clinoptilolite, respectively. Expanding the kaolinite interlayer space from 0.71 to 1.12 nm using DMSO intercalation, did not yield a significant enhancement in the sorption capacity of kaolinite, indicating that the surface and edge sites of the clay are more energetically favored. EDS mapping and elemental analysis of the surface of kaolinite and clinoptilolite revealed more intense signals on the surface of the latter with an even distribution of sorbed Cs+ onto the surfaces of both minerals. PMID:15797389

  7. Effect of sulfate and carbonate minerals on particle-size distributions in arid soils

    Science.gov (United States)

    Goossens, Dirk; Buck, Brenda J.; Teng, Yuazxin; Robins, Colin; Goldstein, Harland L.

    2014-01-01

    Arid soils pose unique problems during measurement and interpretation of particle-size distributions (PSDs) because they often contain high concentrations of water-soluble salts. This study investigates the effects of sulfate and carbonate minerals on grain-size analysis by comparing analyses in water, in which the minerals dissolve, and isopropanol (IPA), in which they do not. The presence of gypsum, in particular, substantially affects particle-size analysis once the concentration of gypsum in the sample exceeds the mineral’s solubility threshold. For smaller concentrations particle-size results are unaffected. This is because at concentrations above the solubility threshold fine particles cement together or bind to coarser particles or aggregates already present in the sample, or soluble mineral coatings enlarge grains. Formation of discrete crystallites exacerbates the problem. When soluble minerals are dissolved the original, insoluble grains will become partly or entirely liberated. Thus, removing soluble minerals will result in an increase in measured fine particles. Distortion of particle-size analysis is larger for sulfate minerals than for carbonate minerals because of the much higher solubility in water of the former. When possible, arid soils should be analyzed using a liquid in which the mineral grains do not dissolve, such as IPA, because the results will more accurately reflect the PSD under most arid soil field conditions. This is especially important when interpreting soil and environmental processes affected by particle size.

  8. Marine meiofauna, carbon and nitrogen mineralization in sandy and soft sediments of Disko Bay, West Greenland

    DEFF Research Database (Denmark)

    Rysgaard, S.; Christensen, P.B.; Sørensen, Martin Vinther; Funch, P.; Berg, P.

    2000-01-01

    Organic carbon mineralization was studied in a shallow-water (4 m), sandy sediment and 2 comparatively deep-water (150 and 300 m), soft sediments in Disko Bay, West Greenland. Benthic microalgae inhabiting the shallow-water locality significantly affected diurnal O-2 conditions within the surface...... and was, together with organotrophic O-2 respiration, the most important pathway for carbon mineralization within these sediments. The obtained process rates were comparable to mineralization rates from much warmer localities, suggesting that benthic mineralization in arctic marine environments is...... belonging to Platyhelminthes, Rotifera, Gastrotricha, and Protodriloidae (Polychaeta) occurred only at the sandy locality, whereas Kinorhyncha, Foraminifera, and Cumacea (Crustacea) occurred only at the muddy stations. The larger number of meiofauna individuals at the sandy locality may in part be explained...

  9. Remediation of hexavalent chromium from aqueous solution using clay mineral Fe(II)-montmorillonite: Encompassing anion exclusion impact

    Science.gov (United States)

    Vinuth, Mirle; Bhojya Naik, Halehatty Seethya; Manjanna, Jayappa

    2015-12-01

    We have explored the highly efficient and environmentally benign clay mineral, Fe(II)-montmorillonite, for the reduction of Cr(VI) in aqueous solution. Fe(II)-Mt was treated with K2Cr2O7 solution at different pH, temperature and solid-to-liquid ratio. The [Cr2O7]2- was estimated by UV-vis spectra with a correction for anion exclusion impact. In general, the Cr(VI) reduction was rapid at acidic pH and increased with temperature up to 50 °C. A complete reduction occurred in about 5 min at pH 3-5. The time taken for complete reduction at 0 °C, RT (30 °C) and 40 °C are 12 min, 8 min and 5 min, respectively. The reduction followed by immobilization of Cr(III) on the spent clay mineral was well characterized by EDX and chemical extraction analysis. This remediation process could be easily scaled-up for real system applications.

  10. A carbon powder-nanotube composite cathode for non-aqueous lithium-air batteries

    International Nuclear Information System (INIS)

    Highlights: • A composite cathode made of carbon powder and nanotubes is proposed. • The new electrode enables a substantial increase in the capacity and cycle number. • The improved performance can be mainly attributed to the enlarged pore spaces. - Abstract: Carbon powder has been predominately used to form cathode electrodes for non-aqueous lithium-air batteries, mainly due to their large specific surface area. An issue, however, with carbon-powder based cathodes is the large oxygen transport resistance due to limited pore spaces resulting from the packing with nanosized spherical particles, leading to a practical discharge capacity much lower than the theoretical value. The present work addresses this issue by proposing a composite cathode made of carbon powder and nanotubes for non-aqueous lithium-air batteries. The discharge performance characterizations show that the discharge capacity of the cathode with mixed carbon materials increases with an increase in the ratio of carbon nanotubes to powder. At the ratio of 1:1, the highest volumetric and the gravimetric capacity are achieved, which are respectively 67.2% and 36.3% higher than those with the cathode made of pure carbon powder. It is further demonstrated that the battery with the composite cathode at a fixed capacity of 1.0 mA h/cm2 exhibits a cycle life of up to 50 cycles, which is nearly twice the cycle number of the battery with its cathode made of pure carbon powder. The mechanism leading to the improved performance can be mainly attributed to the improved oxygen transport as the result of enlarged pore spaces with an appropriate composition of spherical carbon powder and cylindrical carbon nanotubes

  11. Removal of Uranium From Aqueous Solution by Carbon Nanotubes.

    Science.gov (United States)

    Yu, Jing; Wang, Jianlong

    2016-10-01

    The adsorption of uranium onto carbon nanotubes (CNTs) was investigated. The effect of solution pH, contact time, initial uranium concentration, and temperature on the adsorption capacity of uranium was determined. CNTs were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD), Raman spectra, and the Fourier infrared spectra (FTIR). The diameters of the CNTs varied from 10 to 50 nm in diameter and 1 ~ 2 μm in length. FTIR spectra analysis indicated that carboxyl groups were involved in adsorption of U(VI) by CNTs. The experimental results showed that U(VI) adsorption onto CNTs reached equilibrium within 10 min, and the removal efficiency was 95% at pH = 5. The adsorption kinetics of U(VI) could be described by a pseudo first-order kinetic model. The adsorption isotherm conformed to the Slips model. The adsorption process was spontaneous and endothermic. PMID:27575349

  12. Complete mineralization of perfluorooctanoic acid (PFOA) by γ-irradiation in aqueous solution

    OpenAIRE

    Ze Zhang; Jie-Jie Chen; Xian-Jin Lyu; Hao Yin; Guo-Ping Sheng

    2014-01-01

    Decomposition of perfluorooctanoic acid (C7F15COOH, PFOA) has been gaining increasing interests because it is a ubiquitous environmental contaminant and resistant to the most conventional treatment processes. In this work, the rapid and complete mineralization of PFOA and simultaneous defluorination were achieved by γ-ray irradiation with a 60Co source. The degradation rate of PFOA by γ-ray irradiation would be high, and a pseudo-first-order kinetic rate constant of 0.67 h−1 could be achieved...

  13. Carbon and nitrogen mineralization of harvesting residues of Pinus sylvestris L. during aerobic laboratory incubation

    International Nuclear Information System (INIS)

    The carbon and nitrogen mineralization dynamics of Pinus sylvestris L. harvesting residues, when mixed with an acidic, nitrifying fen peat, were studied during aerobic, laboratory incubation at 20 deg C over 12 weeks. Green needle, brown needle and fine root showed a pattern of curvilinear decline in C mineralization rate with time. The total amounts of C mineralized from those residues, expressed as a percentage of their initial C content, were 52, 41 and 16%. Stem bark and stem wood mineralized more slowly; the value for stem bark was near zero. With the exception of stem bark, the harvesting residues enhanced the mineralization of added 14C- labelled glucose. During the early decomposition of the pine residues, the degree of net N immobilization of mineral N was related to the initial C/N ratio or total N concentration of the residues and net N mineralization was negatively correlated with mineralization of C. The remineralization rate of freshly immobilized N was estimated as seven times faster than the mineralization rate of the more recalcitrant native N from the fen peat. The added pine residues did not influence measurably the nitrification capacity of the fen peat. 40 refs, 3 figs, 7 tabs

  14. RICE BRAN CARBON: AN ALTERNATIVE TO COMMERCIAL ACTIVATED CARBON FOR THE REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS SOLUTION

    OpenAIRE

    Syed Hadi Hasan; Deeksha Ranjan

    2010-01-01

    Rice bran carbon (RBC) prepared from rice bran (an agricultural waste) was successfully utilized for the removal of hexavalent chromium from aqueous solution. The potentiality of RBC was tested and compared with commercial activated carbon (CAC), and it was found that RBC removed 95% of hexavalent chromium at pH 2, 1000 µM Cr(VI) concentration, temperature 30 oC, and adsorbent dose of 2 g/L. The maximum uptake of total chromium obtained by applying the Langmuir isotherm model was 138.88 mg/g ...

  15. Preliminary Nanosims Analysis of Carbon Isotope of Carbonates in Calcium-Aluminum-Rich Inclusions

    OpenAIRE

    Guan, Y.; Paque, J. M.; Burnett, D. S.; Eiler, J. M.

    2009-01-01

    Carbonate minerals observed in primitive meteorites are products of either terrestrial weathering or aqueous alteration in the early solar system. Most of the carbonate minerals in carbonaceous chondrites occur primarily as isolated grains in matrix, as crosscutting veins, or as replacement minerals in chondrules [e.g., 1, 2]. A few calcium-aluminum-rich inclusions (CAIs) have been reported containing carbonate minerals as well [2, 3]. The C and O isotopes of carbonates in c...

  16. Carbon, oxygen and sulfur isotope studies of hydrothermal mineralization in the Gavnunim valley, Makhtesh Ramon, Israel

    International Nuclear Information System (INIS)

    Quartz and sulfide mineral from polymetallic vein-type mineralization within the quartz syenites of the Gavnunim valley, Makhtesh Ramon, exhibit isotopic composition quite different from the hypothermal ore occurrence. Quartz samples have δ18O in the range 19.2 to 25.3 per mille and the δ34S of sulfides varies from 17.5 to -30.6 per mille. At mineral deposition temperatures of 200-350 degree Celsius this compositional ranges are strongly indicative of isotopic buffering of the fluids by sediments in contact with the intrusive rocks. The distribution of δ13C and δ18O in secondary carbonates is consistent with epigenetic remobilization. The mineralization phenomena in the Gavnunim valley are constraint to the later stages of magmatic activity, when circulating hypothermal fluids moving through the sediments infiltrated fractures within the roof of the igneous body and deposited primary sulfide and gangue minerals. (author)

  17. Characterization of surface processes on mineral surfaces in aqueous solutions. Annual report for fiscal year 1993

    International Nuclear Information System (INIS)

    Performance assessments by Los Alamos National Laboratory for the DOE's Yucca Mountain Site Characterization Project (YMP) are being done investigating the environmental risk related to long-term disposal of hazardous wastes resulting from the use of radioactive materials that must subsequently be isolated from the environment. The YMP site, located in southwestern Nevada, is intended for the storage of high-level wastes generated by nuclear energy-related activities, including spent fuel and waste from reprocessed fuel rods. The work covered by this contract is necessary for producing a defensible model and dataset, and may be critical for evaluation of repository compliance. This work, performed by the Environmental Engineering and Science research group at Stanford University, will quantify the adsorption of uranyl on various minerals. The project's principle objective is to provide sorption coefficients for uranyl and other ions of interest to predict radionuclide movements form the repository to accessible environments. This adsorption data is essential for the unambiguous interpretation of field experiments and observations. In this report, details of the activity and progress made with respect to the study of uranyl adsorption on mineral surfaces is presented and discussed

  18. Decolorisation of Reactive Red 120 Dye by Using Single-Walled Carbon Nanotubes in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Edris Bazrafshan

    2013-01-01

    Full Text Available Dyes are one of the most hazardous chemical compound classes found in industrial effluents and need to be treated since their presence in water bodies reduces light penetration, precluding the photosynthesis of aqueous flora. In the present study, single-walled carbon nanotubes (SWCNTs was used as an adsorbent for the successful removal of Reactive Red 120 (RR-120 textile dye from aqueous solutions. The effect of various operating parameters such as initial concentration of dye, contact time, adsorbent dosage and initial pH was investigated in order to find the optimum adsorption conditions. Equilibrium isotherms were used to identify the possible mechanism of the adsorption process. The optimum pH for removing of RR-120 dye from aqueous solutions was found to be 5 and for this condition maximum predicted adsorption capacity for RR-120 dye was obtained as 426.49 mg/g. Also, the equilibrium data were also fitted to the Langmuir, Freundlich and BET equilibrium isotherm models. It was found that the data fitted to BET (R2=0.9897 better than Langmuir (R2=0.9190 and Freundlich (R2=0.8819 model. Finally it was concluded that the single-walled carbon nanotubes can be used for dye removal from aqueous solutions.

  19. Migration of dissolved organic carbon in biochars and biochar-mineral complexes

    OpenAIRE

    Yun Lin; Paul Munroe; Stephen Joseph; Rita Henderson

    2012-01-01

    The objective of this work was to determine the contribution of dissolved organic carbon (DOC) from a biochar mineral complex (BMC), so as to better understand the interactions between DOC, biochar, clay, and minerals during thermal treatment, and the effects of BMC on amended soils. The BMC was prepared by heating a mixture of a H3PO4-treated saligna biochar from Acacia saligna, clays, other minerals, and chicken manure. The BMC was applied to a sandy loam soil in Western Australia, where wh...

  20. ATOMIC-LEVEL IMAGING OF CO2 DISPOSAL AS A CARBONATE MINERAL: OPTIMIZING REACTION PROCESS DESIGN; ANNUAL

    International Nuclear Information System (INIS)

    Fossil fuels, especially coal, can support the energy demands of the world for centuries to come, if the environmental problems associated with CO(sub 2) emissions can be overcome. Permanent and safe methods for CO(sub 2) capture and disposal/storage need to be developed. Mineralization of stationary-source CO(sub 2) emissions as carbonates can provide such safe capture and long-term sequestration. Mg-rich lamellar-hydroxide based minerals (e.g., brucite and serpentine) offer a class of widely available, low-cost materials, with intriguing mineral carbonation potential. Carbonation of such materials inherently involves dehydroxylation, which can disrupt the material down to the atomic level. As such, controlled dehydroxylation before and/or during carbonation may provide an important parameter for enhancing carbonation reaction processes. Mg(OH)(sub 2) was chosen as the model material for investigating lamellar hydroxide mineral dehydroxylation/carbonation mechanisms due to (i) its structural and chemical simplicity, (ii) interest in Mg(OH)(sub 2) gas-solid carbonation as a potentially cost-effective CO(sub 2) mineral sequestration process component, and (iii) its structural and chemical similarity to other lamellar-hydroxide-based minerals (e.g., serpentine-based minerals) whose carbonation reaction processes are being explored due to their low-cost CO(sub 2) sequestration potential. Fundamental understanding of the mechanisms that govern dehydroxylation/carbonation processes is essential for cost optimization of any lamellar-hydroxide-based mineral carbonation sequestration process

  1. Effects of additives on 2,4,6-trinitrotoluene (TNT) removal and its mineralization in aqueous solution by gamma irradiation

    International Nuclear Information System (INIS)

    The effects of additives (i.e., methanol, EDTA, mannitol, thiourea, nitrous oxide, oxygen and ozone) on gamma irradiation of 2,4,6-trinitrotoluene (TNT) were investigated to elucidate the initial reaction mechanism of TNT degradation and suggest an practical method for complete by-product removal. All additives, except thiourea, significantly increased the TNT removal efficiency by gamma irradiation. The overall results of the additive experiments implied that the TNT decomposition would be initiated by ·OH, eaq-, and HO2·/O2·-, and also implied that ·H did not have any direct effect on the TNT decomposition. Additions of methanol and nitrous oxide were more effective in TNT removal than the other additives, achieving complete removal of TNT at doses below 20 kGy. Total organic carbon (TOC) of the irradiated solution was analyzed to evaluate the degree of TNT mineralization under the additive conditions. TOC under the nitrous oxide addition was removed rapidly, and complete TNT mineralization was thus achieved at 50 kGy. Methanol addition was very effective in the TNT removal, but it was not effective in reduction in TOC. Trinitrobenzene (TNB), oxalic acid and glyoxalic acid were detected as radiolytic organic by-products, while ammonia and nitrate were detected as radiolytic inorganic by-products. The most efficient TNT removal and its mineralization by gamma irradiation would be achieved by supersaturating the solution with nitrous oxide before irradiation.

  2. Soil carbon mineralization following biochar addition associated with external nitrogen

    Directory of Open Access Journals (Sweden)

    Rudong Zhao

    2015-12-01

    Full Text Available Biochar has been attracting increasing attention for its potentials of C sequestration and soil amendment. This study aimed to understand the effects of combining biochar with additional external N on soil C mineralization. A typical red soil (Plinthudults was treated with two biochars made from two types of plantation-tree trunks (soil-biochar treatments, and was also treated with external N (soil-biochar-N treatments. All treatments were incubated for 42 d. The CO2-C released from the treatments was detected periodically. After the incubation, soil properties such as pH, microbial biomass C (MBC, and microbial biomass N (MBN were measured. The addition of biochar with external N increased the soil pH (4.31-4.33 compared to the soil treated with external N only (4.21. This was not observed in the comparison of soil-biochar treatments (4.75-4.80 to soil only (4.74. Biochar additions (whether or not they were associated with external N increased soil MBC and MBN, but decreased CO2-C value per unit total C (added biochar C + soil C according to the model fitting. The total CO2-C released in soil-biochar treatments were enhanced compared to soil only (i.e., 3.15 vs. 2.57 mg and 3.23 vs. 2.45 mg, which was attributed to the labile C fractions in the biochars and through soil microorganism enhancement. However, there were few changes in soil C mineralization in soil-biochar-N treatments. Additionally, the potentially available C per unit total C in soil-biochar-N treatments was lower than that observed in the soil-biochar treatments. Therefore, we believe in the short term, that C mineralization in the soil can be enhanced by biochar addition, but not by adding external N concomitantly.

  3. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    OpenAIRE

    Fei Yu; Jie Ma; Sheng Han

    2014-01-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kin...

  4. Effective Degradation of Aqueous Tetracycline Using a Nano-TiO2/Carbon Electrocatalytic Membrane

    OpenAIRE

    Zhimeng Liu; Mengfu Zhu; Zheng Wang; Hong Wang; Cheng Deng; Kui Li

    2016-01-01

    In this work, an electrocatalytic membrane was prepared to degrade aqueous tetracycline (TC) using a carbon membrane coated with nano-TiO2 via a sol-gel process. SEM, XRD, EDS, and XPS were used to characterize the composition and structure of the electrocatalytic membrane. The effect of operating conditions on the removal rate of tetracycline was investigated systematically. The results show that the chemical oxygen demand (COD) removal rate increased with increasing residence time while it ...

  5. Slow reactivation of lyophilized bovine carbonic anhydrase upon dissolution in aqueous solution studied by radiotracer techniques

    International Nuclear Information System (INIS)

    Carbonic anhydrase undergoes reversible denaturation upon lyophilization. Full reactivation requires 30-60 min equilibration time following dissolution in aqueous buffers. The recombination of the Zn2+ cofactor with the active site, investigated by 65Zn tracer studies, is clearly shown to account for only the initial stage of the reactivation process and amounts to only a few per cent of the total reactivation. (author)

  6. A Quantitative Investigation of CO2 Sequestration by Mineral Carbonation

    OpenAIRE

    Mohammad, Muneer; Ehsani, Mehrdad

    2015-01-01

    Anthropogenic activities have led to a substantial increase in carbon dioxide (CO2), a greenhouse gas (GHG), contributing to heightened concerns of global warming. In the last decade alone CO2 emissions increased by 2.0 ppm/yr. globally. In the year 2009, United States and China contributed up to 43.4% of global CO2 emissions. CO2 capture and sequestration have been recognized as promising solutions to mitigate CO2 emissions from fossil fuel based power plants. Typical techniques for carbon c...

  7. Effect of sterilization on mineralization of straw and black carbon

    DEFF Research Database (Denmark)

    Bobul'ská, Lenka; Bruun, Sander; Fazekašová, Danica

    2013-01-01

    The study was aimed at investigating the role of microorganisms in the degradation of BC (black carbon). CO evolution was measured under sterilized and non-sterilized soil using BC and straw amendments. Black carbon and straw were produced from homogenously C labelled roots of barley (Hordeum...... resistance of BC to microbial degradation. The difference between soil respiration in sterilized and non-sterilized soil with plant material was visible from the beginning of the experiment, unlike with BC amendments where differences only occurred after some days. In addition, the CO evolution from...

  8. Mineral replacements during carbonation of peridotite: implications for carbon dioxide sequestration in ultramafic rocks

    Science.gov (United States)

    Beinlich, Andreas; Hövelmann, Jörn; Plümper, Oliver; Austrheim, Hâkon

    2010-05-01

    , together with poorly crystalline serpentine and extremely fine grained talc. Hydrothermal batch experiments (130-160 bar PCO2; 200° C; 1-3 weeks reaction time) show that the alteration product after olivine is the favorable site of reaction presumably due to the large reactive surface area. In contrast, the olivine relicts have reacted to a significantly lesser extend, whereas the serpentine veins remain virtually unreacted. The dissolution of the compartment fillings is followed by nucleation and growth of calcite crystals also revealing that precipitation of calcite is strongly favored over magnesite as soon as the system contains Ca. The preferred precipitation of calcite is also supported by geochemical modeling (using Phreeqc), which shows that the Mg-bearing carbonates (dolomite, magnesite) only form if the fluid is sufficiently depleted in Ca. The compositional and textural differences between different samples as well as different run products from experiments indicate that the described clasts evolved from peridotite due to extreme mobilization of Mg, development of secondary porosity, and infill of carbonates. Mg removed from the clasts is partly consumed by replacement reactions in the vicinity of the clasts where Fe-minerals (almandine) are altered to Mg-minerals (talc). For basins containing abundant peridotite clasts, the outlined process will influence the CO2 and MgO budget. References: IPCC Special report: Carbon Dioxide Capture and Storage, Summary for Policymakers, 2005.

  9. Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery.

    Science.gov (United States)

    Faulconer, Emily K; von Reitzenstein, Natalia V Hoogesteijn; Mazyck, David W

    2012-01-15

    Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 μg/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury-carbon contact chamber with mixing and constant N(2) (g) headspace flow to an oxidizing trap. Mercury adsorption was performed using spiked ultrapure water (100 μg/L Hg). Mercury concentrations were obtained using EPA method 245.1 and cold vapor atomic absorption spectroscopy. MPAC synthesis was optimized for Hg removal and sorbent recovery according to the variables: C:Fe, thermal oxidation temperature and time. The 3:1 C:Fe preserved most of the original sorbent surface area. As indicated by XRD patterns, thermal oxidation reduced the amorphous characteristic of the iron oxides but did not improve sorbent recovery and damaged porosity at higher oxidation temperatures. Therefore, the optimal synthesis variables, 3:1 C:Fe mass ratio without thermal oxidation, which can achieve 92.5% (± 8.3%) sorbent recovery and 96.3% (± 9%) Hg removal. The mass balance has been closed to within approximately ± 15%. PMID:22104766

  10. Fullerene-containing phases obtained from aqueous dispersions of carbon nanoparticles

    Science.gov (United States)

    Rozhkov, S. P.; Kovalevskii, V. V.; Rozhkova, N. N.

    2007-06-01

    The hydration of fullerenes and shungite carbon nanoclusters in aqueous dispersions at various carbon concentrations is studied on frozen samples by EPR with spin probes. It is found that, for stable dispersions of both substances (at carbon concentrations of 0.1 mg/ml), the probe rotation frequency versus 1/T dependences exhibit a plateau in the range 243 257 K, which is probably associated with the peculiarities of freezing of water localized near hydrophobic structures of carbon nanoclusters. Solid phases isolated from supersaturated aqueous dispersions of fullerenes and shungites by slow evaporation of water at temperatures higher than 0°C are examines by electron diffraction and electron microscopy. It is established that obtained films of fullerenes contain at least two phases: fullerite with a face-centered cubic lattice and a phase similar in interplanar spacing and radically different in distribution of intensities of diffraction peaks. It is concluded that this phase is formed by the interaction of fullerenes and water (an analogous phase is found in shungite carbon films). It is found that the morphology of the new crystal phase is characterized by globules of size 20 to 70 nm, for fullerenes, and 10 to 400 nm for shungites. It is established that processes of crystallization of fullerites and fullerene-containing phases are very sensitive to temperature: a decrease in the temperature (within the range from 40 to 1°C) is accompanied by an increase in the new phase content.

  11. Comparison of capacitive behavior of activated carbons with different pore structures in aqueous and nonaqueous systems

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shao-yun; LI Xin-hai; WANG Zhi-xing; GUO Hua-jun; PENG Wen-jie

    2008-01-01

    The pore structures of two activated carbons from sawdust with KOH activation and coconut-shell with steam activation for supercapacitor were analyzed by N2 adsorption method. The electrochemical properties of both activated carbons in 6mol/L KOH solution and 1mol/L Et4NPF4/PC were compared, and the effect of pore structure on the capacitance was investigated by cyclic voltammetry, AC impedance and charge-discharge measurements. The results indicate that the capacitance mainly depends on effective surface area, but the power property mainly depends on mesoporosity. At low specific current (1A/g), the maximum specific capacitances of 276.3F/g in aqueous system and 123.9F/g in nonaqueous system can be obtained from sawdust activated carbon with a larger surface area of 1808m2/g, but at a high specific current, the specific capacitance of coconut-shell activated carbon with a higher mesoporosity of 75.1% is more excellent. Activated carbon by KOH activation is fitter for aqueous system and that by steam activation is fitter for nonaqueous system.

  12. Microbial Contribution to Organic Carbon Sequestration in Mineral Soil

    Science.gov (United States)

    Soil productivity and sustainability are dependent on soil organic matter (SOM). Our understanding on how organic inputs to soil from microbial processes become converted to SOM is still limited. This study aims to understand how microbes affect carbon (C) sequestration and the formation of recalcit...

  13. Effect of Ginkgo biloba Leaves Aqueous Extract on Carbon

    Directory of Open Access Journals (Sweden)

    Hala A.H. Khattab

    2012-07-01

    Full Text Available Bachground: Oxidative stress plays a pivotal role in the pathogenesis and progression of various liver diseases. Ginkgo biloba leaves extract (GbE have been proved to be an effective antioxidant, thereby can contribute to the prevention and treatment of diseases associated with oxidative stress. The present study aimed to investigate the hepatoprotective effect of GbE on acute liver injury induced using carbon tetrachloride (CCl4 in rats. Material and Methods: Hepatotoxicity was induced in male rats by intraperitoneal (i.p injection of CCl4 1mL/ kg body weight (b.w. for every 72 h for 14 days, GbE was administered orally at a dose of 150 mg/kg b.w., daily started two weeks prior to CCl4 injection and continued until the end of the experiment. Results: CCl4 caused acute liver damage in rats, as evidenced by significant increase serum enzymes activities of aspartate and alanine aminotransferase (ALT & AST and alkaline phosphatase (ALP, and hepatic malondialdehyde (MDA, as well as significant decrease in weight gain percent, serum total protein (TP, high-density lipoprotein cholesterol (HDL-C, and hepatic reduced glutathione (GSH. Pretreatment with GbE prior to CCl4 injection elicited hepatoprotetcive activity by significant decreased the activities of liver enzymes and hepatic MDA, and significant increased the levels of TP, and hepatic GSH, as well as induced significant ameliorated in weight gain percent and lipid profile parameters as compared with CCl4 group. Histopathological examination of the liver tissues of CCl4 group represented the presence of hepatic necrosis associated with cells infiltration and vacuolar degeneration of hepatocytes, while the pretreatment with GbE overcome these changes, the majority of the cells tend to be normal.Conclusion: The present findings indicated that the hepatoprotective effect of GbE against CCl4-induced oxidative damage may be due to its potent antioxidant activity. Therefore, GbE could be of potential

  14. Enhanced U(VI) release from autunite mineral by aerobic Arthrobacter sp. in the presence of aqueous bicarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Katsenovich, Yelena; Carvajal, Denny A.; Wellman, Dawn M.; Lagos, Leonel

    2012-04-20

    The bacterial effect on U(VI) leaching from the autunite mineral (Ca[(UO{sub 2})(PO{sub 4})]{sub 2} {center_dot} 3H{sub 2}O) was investigated to provide a more comprehensive understanding into important microbiological processes affecting autunite stability within subsurface bicarbonate-bearing environments. Experiments were performed in a culture of G975 Arthrobacter oxydans strain, herein referred to as G975, a soil bacterium previously isolated from Hanford Site soil. 91 mg of autunite powder and 50 mL of phosphorus-limiting sterile media were amended with bicarbonate ranging between 1-10 mM in glass reactor bottles and inoculated with G975 strain after the dissolution of autunite was at steady state. SEM observations indicated G975 formed a biofilm on the autunite surface and penetrated the mineral cleavages. The mineral surface colonization by bacteria tended to increase concomitantly with bicarbonate concentrations. Additionally, a sterile cultureware with inserts was used in non-contact bioleaching experiments where autunite and bacteria cells were kept separately. The data suggest the G975 bacteria is able to enhance U(VI) leaching from autunite without the direct contact with the mineral. In the presence of bicarbonate, the damage to bacterial cells caused by U(VI) toxicity was reduced, yielding similar values for total organic carbon (TOC) degradation and cell density compared to U(VI)-free controls. The presence of active bacterial cells greatly enhanced the U(VI) bioleaching from autunite in bicarbonate-amended media.

  15. Minerals

    Directory of Open Access Journals (Sweden)

    Vaquero, M. P.

    1998-08-01

    Full Text Available The possible changes in the mineral composition of food during frying could be the consequence of losses by leaching, or changes in concentrations caused by exchanges between the food and culinary fat of other compounds. The net result depends on the type of food, the frying fat used and the frying process. Moreover, the modifications that frying produces in other nutrients could indirectly affect the availability of dietary minerals. The most outstanding ones are those that can take place in the fat or in the protein. With respect to the interactions between frying oils and minerals, we have recent knowledge concerning the effects of consuming vegetable oils used in repeated fryings of potatoes without turnover, on the nutritive utilization of dietary minerals. The experiments have been carried out in pregnant and growing rats, which consumed diets containing, as a sole source of fat, the testing frying oils or unused oils. It seems that the consumption of various frying oils, with a polar compound content lower or close to the maximum limit of 25% accepted for human consumption, does not alter the absorption and metabolism of calcium, phosphorous, iron or copper. Magnesium absorption from diets containing frying oils tends to increase but the urinary excretion of this element increases, resulting imperceptible the variations in the magnesium balance. The urinary excretion of Zn also increased although its balance remained unchanged. Different studies referring to the effects of consuming fried fatty fish on mineral bioavailability will also be presented. On one hand, frying can cause structural changes in fish protein, which are associated with an increase in iron absorption and a decrease in body zinc retention. The nutritive utilization of other elements such as magnesium, calcium and copper seems to be unaffected. On the other hand; it has been described that an excess of fish fatty acids in the diet produces iron depletion, but when fatty

  16. Reduction of CO2 emissions by mineral carbonation : steelmaking slags as rawmaterial with a pure calcium carbonate end product

    OpenAIRE

    Eloneva, Sanni

    2010-01-01

    Mineral carbonation is one of the options that can contribute to the reduction of carbon dioxide emissions for climate change mitigation purposes. Steel manufacturing, which is one of the biggest industrial sources of CO2 emissions, could benefit from this option by utilizing its own by-products, i.e., steelmaking slags, to combine with CO2. Additional benefits would be achieved if the end product was a pure and marketable calcium carbonate. The utilization of CaCO3 derived from steelmaking s...

  17. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    Science.gov (United States)

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

    2015-10-01

    "Clumped-isotope" thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope "clumps"). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two

  18. Carbon dioxide exchange of a perennial bioenergy crop cultivation on a mineral soil

    OpenAIRE

    Lind, S. E.; Shurpali, N. J.; O. Peltola; Mammarella, I.; N. Hyvönen; Maljanen, M.; M. Räty; Virkajärvi, P.; Martikainen, P J

    2015-01-01

    One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinaceae L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 ...

  19. Carbon dioxide exchange of a perennial bioenergy crop cultivation on a mineral soil

    OpenAIRE

    Lind, Saara E.; Shurpali, Narasinha J.; Peltola, Olli; Mammarella, Ivan; Hyvönen, Niina; Maljanen, Marja; Räty, Mari; Virkajärvi, Perttu; Martikainen, Pertti J.

    2016-01-01

    One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinacea L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 ex...

  20. Influence of Substrate Mineralogy on Bacterial Mineralization of Calcium Carbonate: Implications for Stone Conservation

    OpenAIRE

    Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-01-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carb...

  1. Ab initio prediction of equilibrium boron isotope fractionation between minerals and aqueous fluids at high P and T

    Science.gov (United States)

    Kowalski, Piotr M.; Wunder, Bernd; Jahn, Sandro

    2013-01-01

    Over the last decade experimental studies have shown a large B isotope fractionation between materials carrying boron incorporated in trigonally and tetrahedrally coordinated sites, but the mechanisms responsible for producing the observed isotopic signatures are poorly known. In order to understand the boron isotope fractionation processes and to obtain a better interpretation of the experimental data and isotopic signatures observed in natural samples, we use first principles calculations based on density functional theory in conjunction with ab initio molecular dynamics and a new pseudofrequency analysis method to investigate the B isotope fractionation between B-bearing minerals (such as tourmaline and micas) and aqueous fluids containing HBO and HBO4- species. We confirm the experimental finding that the isotope fractionation is mainly driven by the coordination of the fractionating boron atoms and have found in addition that the strength of the produced isotopic signature is strongly correlated with the Bsbnd O bond length. We also demonstrate the ability of our computational scheme to predict the isotopic signatures of fluids at extreme pressures by showing the consistency of computed pressure-dependent β factors with the measured pressure shifts of the Bsbnd O vibrational frequencies of HBO and HBO4- in aqueous fluid. The comparison of the predicted with measured fractionation factors between boromuscovite and neutral fluid confirms the existence of the admixture of tetrahedral boron species in neutral fluid at high P and T found experimentally, which also explains the inconsistency between the various measurements on the tourmaline-mica system reported in the literature. Our investigation shows that the calculated equilibrium isotope fractionation factors have an accuracy comparable to the experiments and give unique and valuable insight into the processes governing the isotope fractionation mechanisms on the atomic scale.

  2. Geology of carbonate aggregate resources of Illinois, Illinois mineral notes

    Science.gov (United States)

    Goodwin, J. H.

    Carbonate rocks ranging in age from Pennsylvanian through Ordovician provide the principal resources for crushed stone production in Illinois. In the northern third of Illinois, dolomite and calcareous dolomite of the Silurian and Ordovician Systems from the bedrock surface are the basis of a large quarrying industry. One of the largest quarries in the United States wins stone from Silurian reefal dolomite at Thornton, near Chicago. Aggregate for skid-resistant asphalt pavement is produced from Devonian chert in extreme southern Illinois.

  3. Organic carbon concentrations and stocks in Romanian mineral forest soils

    OpenAIRE

    Lucian C. Dincă; Gheorghe Spârchez; Maria Dincă; Viorel N. B. Blujdea

    2012-01-01

    Estimating soils organic carbon stock and its change in time is an actual concern for scientists and climate change policy makers. The present article firstly focus on determination of C stocks in Romania on forest soil types, as well as development of the spatial distribution mapping using a Geographic Information System (GIS) and also the secondly on the quantification of uncertainty associated with currently available data on C concentration on forest soils geometrical layers. Determinatio...

  4. On the neutralization of acid rock drainage by carbonate and silicate minerals

    Science.gov (United States)

    Sherlock, E. J.; Lawrence, R. W.; Poulin, R.

    1995-02-01

    The net result of acid-generating and-neutralizing reactions within mining wastes is termed acid rock drainage (ARD). The oxidation of sulfide minerals is the major contributor to acid generation. Dissolution and alteration of various minerals can contribute to the neutralization of acid. Definitions of alkalinity, acidity, and buffer capacity are reviewed, and a detailed discussion of the dissolution and neutralizing capacity of carbonate and silicate minerals related to equilibium conditions, dissolution mechanism, and kinetics is provided. Factors that determine neutralization rate by carbonate and silicate minerals include: pH, PCO 2, equilibrium conditions, temperature, mineral composition and structure, redox conditions, and the presence of “foreign” ions. Similar factors affect sulfide oxidation. Comparison of rates shows sulfides react fastest, followed by carbonates and silicates. The differences in the reaction mechanisms and kinetics of neutralization have important implications in the prediction, control, and regulation of ARD. Current static and kinetic prediction methods upon which mine permitting, ARD control, and mine closure plans are based do not consider sample mineralogy or the kinetics of the acid-generating and-neutralizing reactions. Erroneous test interpretations and predictions can result. The importance of considering mineralogy for site-specific interpretation is highlighted. Uncertainty in prediction leads to difficulties for the mine operator in developing satisfactory and cost-effective control and remediation measures. Thus, the application of regulations and guidelines for waste management planning need to beflexible.

  5. Capture and mineralization of carbon dioxide from coal combustion flue gas emissions

    Science.gov (United States)

    Attili, Viswatej

    (Proprietary information: PCT/US/2006/49411 and WO/2007/ 081561A) Enormous amounts of carbon dioxide (CO2) released by human activity (anthropogenic), may lead to climate changes that could spread diseases, ruin crops, cause intense droughts and floods, and dramatically raise the sea levels, thereby submerging the low lying coastal regions. The objective of this study was to test whether CO2 and sulfur dioxide (SO2) from flue gases can be directly captured and converted into carbonate and sulfate minerals respectively through the mineralization process of alkaline solid wastes. A flow-through carbonation process was designed to react flue gases directly with alkaline fly ash, under coal combustion power plant conditions. For the first time, CO2 levels in the flue gas were reduced from 13.6% to 9.7% after the reaction with alkaline fly ash in a reaction time of less than 1 minute. Using a combination of Orion RTM plus multi-gas detector, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques, flue gas CO2 mineralization on fly ash particles was detected. This method can simultaneously help in separate, capture, and mineralize anthropogenic CO2 and SO2. Moreover, this process may be environmentally safe and a stable storage for anthropogenic CO2. Capturing anthropogenic CO2 using this mineralization process is an initial step towards developing more efficient methods of reducing industrial point source CO2 emissions into the atmosphere.

  6. Microbially Accelerated Carbonate Mineral Precipitation as a Strategy for in Situ Carbon Sequestration and Rehabilitation of Asbestos Mine Sites.

    Science.gov (United States)

    McCutcheon, Jenine; Wilson, Siobhan A; Southam, Gordon

    2016-02-01

    A microbially accelerated process for the precipitation of carbonate minerals was implemented in a sample of serpentinite mine tailings collected from the abandoned Woodsreef Asbestos Mine in New South Wales, Australia as a strategy to sequester atmospheric CO2 while also stabilizing the tailings. Tailings were leached using sulfuric acid in reaction columns and subsequently inoculated with an alkalinity-generating cyanobacteria-dominated microbial consortium that was enriched from pit waters at the Woodsreef Mine. Leaching conditions that dissolved 14% of the magnesium from the serpentinite tailings while maintaining circumneutral pH (1800 ppm, pH 6.3) were employed in the experiment. The mineralogy, water chemistry, and microbial colonization of the columns were characterized following the experiment. Micro-X-ray diffraction was used to identify carbonate precipitates as dypingite [Mg5(CO3)4(OH)2·5H2O] and hydromagnesite [Mg5(CO3)4(OH)2·4H2O] with minor nesquehonite (MgCO3·3H2O). Scanning electron microscopy revealed that carbonate mineral precipitates form directly on the filamentous cyanobacteria. These findings demonstrate the ability of these organisms to generate localized supersaturating microenvironments of high concentrations of adsorbed magnesium and photosynthetically generated carbonate ions while also acting as nucleation sites for carbonate precipitation. This study is the first step toward implementing in situ carbon sequestration in serpentinite mine tailings via microbial carbonate precipitation reactions. PMID:26720600

  7. CO2 mitigation potential of mineral carbonation with industrial alkalinity sources in the United States.

    Science.gov (United States)

    Kirchofer, Abby; Becker, Austin; Brandt, Adam; Wilcox, Jennifer

    2013-07-01

    The availability of industrial alkalinity sources is investigated to determine their potential for the simultaneous capture and sequestration of CO2 from point-source emissions in the United States. Industrial alkalinity sources investigated include fly ash, cement kiln dust, and iron and steel slag. Their feasibility for mineral carbonation is determined by their relative abundance for CO2 reactivity and their proximity to point-source CO2 emissions. In addition, the available aggregate markets are investigated as possible sinks for mineral carbonation products. We show that in the U.S., industrial alkaline byproducts have the potential to mitigate approximately 7.6 Mt CO2/yr, of which 7.0 Mt CO2/yr are CO2 captured through mineral carbonation and 0.6 Mt CO2/yr are CO2 emissions avoided through reuse as synthetic aggregate (replacing sand and gravel). The emission reductions represent a small share (i.e., 0.1%) of total U.S. CO2 emissions; however, industrial byproducts may represent comparatively low-cost methods for the advancement of mineral carbonation technologies, which may be extended to more abundant yet expensive natural alkalinity sources. PMID:23738892

  8. Carbon Mineralization in Two Ultisols Amended with Different Sources and Particle Sizes of Pyrolyzed Biochar

    Science.gov (United States)

    Biochar produced during pyrolysis has the potential to enhance soil fertility and reduce greenhouse gas emissions. The influence of biochar properties (e.g., particle size) on both short- and long-term carbon (C) mineralization of biochar remains unclear. There is minimal informa...

  9. Organic carbon concentrations and stocks in Romanian mineral forest soils

    Directory of Open Access Journals (Sweden)

    Lucian C. Dincă

    2012-11-01

    Full Text Available Estimating soils organic carbon stock and its change in time isan actual concern for scientists and climate change policy makers. Thepresent article firstly focus on determination of C stocks in Romania on forest soil types, as well as development of the spatial distribution mapping using a Geographic Information System (GIS and also the secondly on the quantification of uncertainty associated with currently available data on C concentration on forest soils geometrical layers. Determination of C stock was done based on forest management plans database created over 2000-2006. Unlike original database, the data for this study was harmonized on following depths: 0-10 cm, 10-20 cm, 20-40 cm, and > 40 cm. Then, the obtained values were grouped by soil types, resulting average values for the main forest soils from Romania. A soil area weighted average value of 137 t/ha is calculated for Romania, in the range of estimationsfor other European geographic and climatic areas. The soils that have the largest amount of organic carbon are andosols, vertisols, entic and haplic podzols, whereas the ones that have the smallest values of organic carbon are solonetz and solonchaks. Although current assessment relies on very large number of samples from the forest management planning database, the variability of C concentration remains very large, ~40-50% for coefficient the variation and ~100% of the average, when defining the range of 95% of entire soil population, rather showing the variability than uncertainty of the average estimated. Best fit for C concentration on geometric layersin any forest soil is asymmetric, associated with log-normal distributions.

  10. Organic carbon concentrations and stocks in Romanian mineral forest soils

    Directory of Open Access Journals (Sweden)

    Lucian C. Dincă

    2012-12-01

    Full Text Available Estimating soils organic carbon stock and its change in time is an actual concern for scientists and climate change policy makers. The present article firstly focus on determination of C stocks in Romania on forest soil types, as well as development of the spatial distribution mapping using a Geographic Information System (GIS and also the secondly on the quantification of uncertainty associated with currently available data on C concentration on forest soils geometrical layers. Determination of C stock was done based on forest management plans database created over 2000-2006. Unlike original database, the data for this study was harmonized on following depths: 0-10 cm, 10-20 cm, 20-40 cm, and > 40 cm. Then, the obtained values were grouped by soil types, resulting average values for the main forest soils from Romania. A soil area weighted average value of 137 t/ha is calculated for Romania, in the range of estimations for other European geographic and climatic areas. The soils that have the largest amount of organic carbon are andosols, vertisols, entic and haplic podzols, whereas the ones that have the smallest values of organic carbon are solonetz and solonchaks. Although current assessment relies on very large number of samples from the forest management planning database, the variability of C concentration remains very large, ~40-50% for coefficient the variation and ~100% of the average, when defining the range of 95% of entire soil population, rather showing the variability than uncertainty of the average estimated. Best fit for C concentration on geometric layers in any forest soil is asymmetric, associated with log-normal distributions.

  11. Controlling wear failure of graphite-like carbon film in aqueous environment: Two feasible approaches

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yongxin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Wang Liping, E-mail: lpwang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China); Xue Qunji [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China)

    2011-02-15

    Friction and wear behaviors of graphite-like carbon (GLC) films in aqueous environment were investigated by a reciprocating sliding tribo-meter with ball-on-disc contact. Film structures and wear scars were studied by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and a non-contact 3D surface profiler. A comprehensive wear model of the GLC film in aqueous environment was established, and two feasible approaches to control critical factor to the corresponding wear failure were discussed. Results showed that wear loss of GLC films in aqueous environment was characterized by micro-plough and local delamination. Due to the significant material loss, local delamination of films was critical to wear failure of GLC film in aqueous environment if the film was not prepared properly. The initiation and propagation of micro-cracks within whole films closely related to the occurrence of the films delamination from the interface between interlayer and substrate. The increase of film density by adjusting the deposition condition would significantly reduce the film delamination from substrate, meanwhile, fabricating a proper interlayer between substrate and GLC films to prevent the penetration of water molecules into the interface between interlayer and substrate could effectively eliminate the delamination.

  12. Interactions between diatom aggregates, minerals, particulate organic carbon, and dissolved organic matter: Further implications for the ballast hypothesis

    OpenAIRE

    De La Rocha, Christina,; Nowald, N.; Passow, Uta

    2008-01-01

    Correlations of particulate organic carbon (POC) and mineral fluxes into sediment traps in the deep sea have previously suggested that interactions between organic matter and minerals play a key role in organic matter flux to the deep. Here experiments were carried out in rolling tanks to observe the incorporation of suspended biogenic minerals ( calcium carbonate coccoliths or silica diatom frustules) into diatom aggregates and examine their influence on aggregate character. Addition of high...

  13. Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process.

    Science.gov (United States)

    Regmi, Pusker; Garcia Moscoso, Jose Luis; Kumar, Sandeep; Cao, Xiaoyan; Mao, Jingdong; Schafran, Gary

    2012-10-30

    Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g). PMID:22687632

  14. CO2 sequestration using waste concrete and anorthosite tailings by direct mineral carbonation in gas-solid-liquid and gas-solid routes.

    Science.gov (United States)

    Ben Ghacham, Alia; Cecchi, Emmanuelle; Pasquier, Louis-César; Blais, Jean-François; Mercier, Guy

    2015-11-01

    Mineral carbonation (MC) represents a promising alternative for sequestering CO2. In this work, the CO2 sequestration capacity of the available calcium-bearing materials waste concrete and anorthosite tailings is assessed in gas-solid-liquid and gas-solid routes using 18.2% flue CO2 gas. The objective is to screen for a better potential residue and phase route and as the ultimate purpose to develop a cost-effective process. The results indicate the possibility of removing 66% from inlet CO2 using waste concrete for the aqueous route. However, the results that were obtained with the carbonation of anorthosite were less significant, with 34% as the maximal percentage of CO2 removal. The difference in terms of reactivity could be explained by the accessibility to calcium. In fact, anorthosite presents a framework structure wherein the calcium is trapped, which could slow the calcium dissolution into the aqueous phase compared to the concrete sample, where calcium can more easily leach. In the other part of the study concerning gas-solid carbonation, the results of CO2 removal did not exceed 15%, which is not economically interesting for scaling up the process. The results obtained with waste concrete samples in aqueous phase are interesting. In fact, 34.6% of the introduced CO2 is converted into carbonate after 15 min of contact with the gas without chemical additives and at a relatively low gas pressure. Research on the optimization of the aqueous process using waste concrete should be performed to enhance the reaction rate and to develop a cost-effective process. PMID:26292776

  15. Computational Redox Potential Predictions: Applications to Inorganic and Organic Aqueous Complexes, and Complexes Adsorbed to Mineral Surfaces

    Directory of Open Access Journals (Sweden)

    Krishnamoorthy Arumugam

    2014-04-01

    reduction of actinides and their subsequent immobilization. Highly under-investigated is the role of redox-active semiconducting mineral surfaces as catalysts for promoting natural redox processes. Such knowledge is crucial to derive process-oriented mechanisms, kinetics, and rate laws for inorganic and organic redox processes in nature. In addition, molecular-level details still need to be explored and understood to plan for safer disposal of hazardous materials. In light of this, we include new research on the effect of iron-sulfide mineral surfaces, such as pyrite and mackinawite, on the redox chemistry of actinyl aqua complexes in aqueous solution.

  16. Water-rock interaction during mineral carbonation and volcanic ash weathering

    OpenAIRE

    Helgi Arnar Alfreðsson 1984

    2015-01-01

    The reduction of atmospheric carbon dioxide (CO2) is considered one of the greatest challenges of this century. Carbon capture and storage (CCS) is one of the means proposed to lower the atmospheric CO2 content. The aim of the CarbFix project in Iceland was to design and test a CO2 re-injection system, in which CO2 from the Hellisheidi geothermal power plant was injected, fully dissolved in water, into basaltic rocks. In this way the carbon is mineralized upon basalt dissolution by the precip...

  17. Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

    International Nuclear Information System (INIS)

    In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088 nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088 nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid

  18. Removal of Lead (II Ions from Aqueous Solutions onto Activated Carbon Derived from Waste Biomass

    Directory of Open Access Journals (Sweden)

    Murat Erdem

    2013-01-01

    Full Text Available The removal of lead (II ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS analysis after adsorption reveals the accumulation of lead (II ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2 mg g−1. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous.

  19. Dissolution and carbonation of a serpentinite: Inferences from acid attack and high P-T experiments performed in aqueous solutions at variable salinity

    International Nuclear Information System (INIS)

    Highlights: → In order to perform geological sequestration of CO2, serpentinite should be dissolved by acids or by aqueous solutions. → At atmospheric pressure serpentinite is efficaciously dissolved at 70 deg. C using acid attacks. → At higher P-T conditions, significant carbonation occurs at 30 MPa and 300 deg. C using CO2 saturated aqueous solutions. - Abstract: Dissolution experiments on a serpentinite were performed at 70 deg. C, 0.1 MPa, in H2SO4 solution, in open and closed systems, in order to evaluate the overall dissolution rate of mineral components over different times (4, 9 and 24 h). In addition, the serpentinite powder was reacted with a NaCl-bearing aqueous solution and supercritical CO2 for 24 h at higher pressures (9-30 MPa) and temperatures (250-300 deg. C) either in a stirred reactor or in an externally-heated pressure vessel to assess both the dissolution rate of serpentinite minerals and the progress of the carbonation reaction. Results show that, at 0.1 MPa, MgO extraction from serpentinite ranges from 82% to 98% and dissolution rate varies from 8.5 x 10-10 mole m-2 s-1 to 4.2 x 10-9 mole m-2 s-1. Attempts to obtain carbonates from the Mg-rich solutions by increasing their pH failed since Mg- and NH4- bearing sulfates promptly precipitated. On the other hand, at higher pressures, significant crystallization (5.0-10.4 wt%) of Ca- and Fe-bearing magnesite was accomplished at 30 MPa and 300 deg. C using 100 g L-1 NaCl aqueous solutions. The corresponding amount of CO2 sequestered by crystallization of carbonates is 9.4-15.9 mole%. Dissolution rate (from 6.3 x 10-11 mole m-2 s-1 to 1.3 x 10-10 mole m-2 s-1) is lower than that obtained at 0.1 MPa and 70 deg. C but it is related to pH values much higher (3.3-4.4) than that (-0.65) calculated for the H2SO4 solution. Through a thorough review of previous experimental investigations on the dissolution kinetics of serpentine minerals the authors propose adopting: (i) the log rate [mole m-2 s-1

  20. Dissolution and carbonation of a serpentinite: Inferences from acid attack and high P-T experiments performed in aqueous solutions at variable salinity

    Energy Technology Data Exchange (ETDEWEB)

    Orlando, Andrea, E-mail: orlando@igg.cnr.it [C.N.R., Istituto di Geoscienze e Georisorse, U.O.S. di Firenze, Via G. La Pira, 4, I-50121 Firenze (Italy); Borrini, Daniele [Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, Via G. La Pira, 4, I-50121 Firenze (Italy); Marini, Luigi [Consultant in Applied Geochemistry, Via A. Fratti 253, I-55049 Viareggio (Italy)

    2011-08-15

    Highlights: > In order to perform geological sequestration of CO{sub 2}, serpentinite should be dissolved by acids or by aqueous solutions. > At atmospheric pressure serpentinite is efficaciously dissolved at 70 deg. C using acid attacks. > At higher P-T conditions, significant carbonation occurs at 30 MPa and 300 deg. C using CO{sub 2} saturated aqueous solutions. - Abstract: Dissolution experiments on a serpentinite were performed at 70 deg. C, 0.1 MPa, in H{sub 2}SO{sub 4} solution, in open and closed systems, in order to evaluate the overall dissolution rate of mineral components over different times (4, 9 and 24 h). In addition, the serpentinite powder was reacted with a NaCl-bearing aqueous solution and supercritical CO{sub 2} for 24 h at higher pressures (9-30 MPa) and temperatures (250-300 deg. C) either in a stirred reactor or in an externally-heated pressure vessel to assess both the dissolution rate of serpentinite minerals and the progress of the carbonation reaction. Results show that, at 0.1 MPa, MgO extraction from serpentinite ranges from 82% to 98% and dissolution rate varies from 8.5 x 10{sup -10} mole m{sup -2} s{sup -1} to 4.2 x 10{sup -9} mole m{sup -2} s{sup -1}. Attempts to obtain carbonates from the Mg-rich solutions by increasing their pH failed since Mg- and NH{sub 4}- bearing sulfates promptly precipitated. On the other hand, at higher pressures, significant crystallization (5.0-10.4 wt%) of Ca- and Fe-bearing magnesite was accomplished at 30 MPa and 300 deg. C using 100 g L{sup -1} NaCl aqueous solutions. The corresponding amount of CO{sub 2} sequestered by crystallization of carbonates is 9.4-15.9 mole%. Dissolution rate (from 6.3 x 10{sup -11} mole m{sup -2} s{sup -1} to 1.3 x 10{sup -10} mole m{sup -2} s{sup -1}) is lower than that obtained at 0.1 MPa and 70 deg. C but it is related to pH values much higher (3.3-4.4) than that (-0.65) calculated for the H{sub 2}SO{sub 4} solution. Through a thorough review of previous experimental

  1. Theoretical constraints on the effects of pH, salinity, and temperature on clumped isotope signatures of dissolved inorganic carbon species and precipitating carbonate minerals

    OpenAIRE

    Hill, PS; Tripati, AK; Schauble, EA

    2014-01-01

    The use of carbonate 'clumped isotope' thermometry as a geochemical technique to determine temperature of formation of a carbonate mineral is predicated on the assumption that the mineral has attained an internal thermodynamic equilibrium. If true, then the clumped isotope signature is dependent solely upon the temperature of formation of the mineral without the need to know the isotopic or elemental composition of coeval fluids. However, anomalous signatures can arise under disequilibrium co...

  2. Non-selective oxidation of humic acid in heterogeneous aqueous systems: a comparative investigation on the effect of clay minerals.

    Science.gov (United States)

    Kavurmaci, Sibel Sen; Bekbolet, Miray

    2014-01-01

    Application of photocatalysis for degradation of natural organic matter (NOM) has received wide interest during the last decades. Besides NOM, model compounds more specifically humic acids (HAs) were also studied. As a continuation of the previous research, TiO2 photocatalytic degradation of HA was investigated in the presence of clay minerals, i.e., montmorillonite (Mt) and kaolinite (Kt). Degradation of HA was expressed by the pseudo-first-order kinetic modelling of dissolved organic carbon (DOC) and UV-VIS parameters (Colour436 and UV254). A slight rate enhancement was attained for Colour436 and UV254 in the presence of either Mt or Kt. The presence of clay particles did not significantly change the DOC degradation rate of HA. The effect of ionic strength (Ca2+ loading from 5 x 10(-4) M to 5 x 1(-3) M) was also assessed for the photocatalytic degradation of sole HA and HA in the presence of either Mt or Kt. Following photocatalytic treatment, molecular size distribution profiles of HA were presented. Besides the effective removal of higher molecular size fractions (100 and 30 kDa fractions), transformation to lower molecular size fractions (TiO2 and Mt or Kt both prior to and following photocatalysis. This study demonstrated that photocatalysis could be applicable for DOC degradation in the presence of clay minerals in natural waters. PMID:25145193

  3. What Are the Time Scales for Carbonate Mineral Sequestration in the Subsurface?

    Science.gov (United States)

    Steefel, C. I.; Landrot, G.; Bolton, E. W.; Pride, S. R.

    2013-12-01

    Mineral trapping of CO2 in the subsurface is acknowledged to be the most secure form of sequestration, but some studies have suggested that the process is extremely slow, perhaps on the order of 10,000 years or more. But what are the arguments for these long time scales based on? Certainly part of it has to do with the slow dissolution rates of silicates needed to provide a source of cations (Ca2+, Mg2+, and Fe2+) and alkalinity for carbonate precipitation. Rates of dissolution for many silicates are very slow (e.g., albitic plagioclase and chlorite), while other silicate minerals (anorthitic feldspar, olivine) dissolve appreciably faster. Determining which mineral is rate-limiting in the case of the faster dissolving silicates (is it the dissolving silicate or precipitating carbonate?), however, is not always straightforward without a careful analysis of dissolution and precipitation as a coupled process. We use micro-continuum modeling to address the issue of time scales for carbonate mineral trapping of CO2. Two sets of simulations have been carried out: 1) largely generic simulations at the centimeter scale that include heterogeneous distributions of both residually trapped scCO2 and reactive mineral phases (Ca-bearing plagioclase and chlorite), and 2) flow plus diffusion and pure diffusion simulations of the reactivity of a reservoir sandstone from a scCO2 pilot injection site at Cranfield, Mississippi. The first set of simulations are designed specifically to examine the assumption that the reservoir within which carbonate mineral precipitation might occur is well-mixed and therefore characterized everywhere by the low pH values typical of brine in equilibrium with supercritical CO2. Our analysis of physically and chemically heterogeneous subsurface materials, especially during the residual trapping stage, suggest that local chemical microenvironments can develop in which pH, alkalinity, and cation concentrations rise sufficiently high that substantial

  4. Modeling reaction-driven cracking during mineral carbonation in peridotite for CO2 sequestration

    Science.gov (United States)

    Paukert, A. N.; Sonnenthal, E. L.; Matter, J.; Kelemen, P. B.

    2013-12-01

    In situ mineral carbonation in mantle peridotite has been proposed as a mechanism for long-term, environmentally benign CO2 sequestration1,2. This process converts peridotite and CO2 to carbonate minerals, like magnesite, in the subsurface, providing permanent and safe storage of the CO2. The volume that can be sequestered in this manner is an open question as peridotite carbonation involves a positive volume change and peridotite aquifers have limited porosity and permeability to accommodate the addition of solid volume. Conversion of peridotite to magnesite results in a volume increase of ~44%, which will fill the existing pore space and could limit the extent of carbonation by reducing porosity and permeability, clogging fluid flow paths, and armoring the reactive surface area. Alternatively, the force of crystallization and changes in fluid pressure from carbonation could act as driving forces for mechanical deformation and fracture propagation within the peridotite, creating new porosity, permeability, and reactive surface area, allowing carbonation to continue3. Natural examples of peridotite that have been entirely converted to magnesite suggest that reactive cracking from mineral carbonation is possible given the right conditions, such as elevated temperature and pCO2 2. Results will be presented from a reactive transport model that has been developed for peridotite carbonation using TOUGHREACT v.24. This model evaluates water and CO2 flow through peridotite fractured at different scales using a multiple continuum mesh. The effect of fluid flow, chemical reactions, and porosity and permeability feedbacks on carbonation rate and extent are explored, as is the effect of temperature. Peridotite carbonation is exothermic, so the release of heat of reaction could be balanced with the fluid injection temperature to maintain the 185oC conditions that facilitate the fastest carbonation rate2. The effect of fluid temperature and flow rate on the rate of carbonation

  5. Phase transitions of aqueous atmospheric particles: Crystallization of ammonium salts promoted by oxide mineral constituents

    Science.gov (United States)

    Han, Jeong-Ho

    2001-09-01

    Knowledge of the hygroscopic response of aerosols is a fundamental factor necessary for the accurate quantitative modeling of visibility degradation, global warming, PM-10 health issues, cloud microphysics, and the oxidizing capacity of the troposphere. At the present time, however, our current understanding of phase transitions is insufficient to develop accurate quantitative models. The discrepancy between current atmospheric models and field measurements originates mainly from a lack of understanding of the efflorescence of real atmospheric particles. While there have been many studies on the homogeneous nucleation of the soluble organic, inorganic, or multi-component materials, many recent in situ field measurements with single-particle mass spectrometry reveal that the individual particles in the troposphere are primarily composed of more than one component. One of the common mixed component particle types contains both water- soluble and insoluble components. Through atmospheric processes, the soluble component can be expected to form a coating around the insoluble constituents. This type of atmospheric particles is very important because the insoluble constituent can play a role as a template for the crystallization of the soluble components by heterogeneous nucleation. In the atmosphere, the most prevalent insoluble constituents are mineral dusts, which have their origin from Saharan and Gobbi deserts. The existence of these coated particles has been supported by several field measurements as well as model studies. Therefore, it becomes imperative to simulate more realistic atmospheric particles for more exact (or realistic) understanding the phase transition of the ambient aerosol particles in the real world. In this context, a series of studies has been completed to solve the aforementioned problems in the phase transition study and to better understand the heterogeneous nucleation of these internally mixed particles. An in-line tube furnace has been

  6. Comparison of activated carbon and bottom ash removal of reactive dye from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, A.R.; Gunes, Y.; Karakaya, N.; Gunes, E. [Trakya University, Tekirdag (Turkey). Dept. of Environmental Engineering

    2007-03-15

    The adsorption of reactive dye from synthetic aqueous solution onto granular activated carbon (GAC) and coal-based bottom ash (CBBA) were studied under the same experimental conditions. As an alternative to GAC CBBA was used as adsorbent for dye removal from aqueous solution. The amount of Vertigo Navy Marine (VNM) adsorbed onto CBBA was lower compared with GAC at equilibrium and dye adsorption capacity increased from 0.71 to 3.82 mg g{sup -1}, and 0.73 to 6.35 mg g{sup -1} with the initial concentration of dye from 25 to 300 mg l{sup -1} respectively. The initial dye uptake of CBBA was not so rapid as in the case of GAC and the dye uptake was slow and gradually attained equilibrium.

  7. [Effects of different types of litters on soil organic carbon mineralization].

    Science.gov (United States)

    Shi, Xue-Jun; Pan, Jian-Jun; Chen, Jin-Ying; Yang, Zhi-Qiang; Zhang, Li-Ming; Sun, Bo; Li, Zhong-Pei

    2009-06-15

    Using litter incubation experiment in laboratory, decomposition discrepancies of four typical litters from Zijin Mountain were analyzed. The results show that organic carbon mineralization rates of soil with litters all involve fast and slow decomposition stages, and the differences are that the former has shorter duration,more daily decomposition quantity while the latter is opposite. Organic carbon mineralization rates of soil with litters rapidly reached maximum in the early days of incubation, and the order is soil with Cynodon dactylon litter (CK + BMD) (23.88 +/- 0.62) mg x d(-1), soil with Pinus massoniana litter (CK+ PML) (17.93 +/- 0.99) mg x d(-1), soil with Quercus acutissima litter (CK+ QAC) (15.39 +/- 0.16) mg x d(-1) and soil with Cyclobalanopsis glauca litter (CK + CGO) (7.26 +/- 0.34) mg x d(-1), and with significant difference between each other (p Power curve model can describe the trends of organic carbon mineralization rate and mineralized accumulation amount,which has a good correlation with their change. PMID:19662876

  8. Removal of Methylene Blue from Aqueous Solution by Activated Carbon Prepared from Pea Shells (Pisum sativum

    Directory of Open Access Journals (Sweden)

    Ünal Geçgel

    2013-01-01

    Full Text Available An activated carbon was prepared from pea shells and used for the removal of methylene blue (MB from aqueous solutions. The influence of various factors such as adsorbent concentration, initial dye concentration, temperature, contact time, pH, and surfactant was studied. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. The adsorption isotherm was found to follow the Langmuir model. The monolayer sorption capacity of activated carbon prepared from pea shell for MB was found to be 246.91 mg g−1 at 25 ∘C. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. Kinetic studies showed that the adsorption followed pseudo-second-order kinetic model. Various thermodynamic parameters such as , , and were evaluated. The results in this study indicated that activated carbon prepared from pea shell could be employed as an adsorbent for the removal of MB from aqueous solutions.

  9. Enhanced Oil Recovery from Oil-wet Carbonate Rock by Spontaneous Imbibition of Aqueous Surfactant Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Standnes, Dag Chun

    2001-09-01

    The main theme of this thesis is an experimental investigation of spontaneous imbibition (SI) of aqueous cationic surfactant solution into oil-wet carbonate (chalk- and dolomite cores). The static imbibition process is believed to represent the matrix flow of oil and water in a fractured reservoir. It was known that aqueous solution of C{sub 12}-N(CH{sub 3}){sub 3}Br (C12TAB) was able to imbibe spontaneously into nearly oil-wet chalk material, but the underlying mechanism was not understood. The present work was therefore initiated, with the following objectives: (1) Put forward a hypothesis for the chemical mechanism underlying the SI of C12TAB solutions into oil-wet chalk material based on experimental data and (2) Perform screening tests of low-cost commercially available surfactants for their ability to displace oil by SI of water into oil-wet carbonate rock material. It is essential for optimal use of the surfactant in field application to have detailed knowledge about the mechanism underlying the SI process. The thesis also discusses some preliminary experimental results and suggests mechanisms for enhanced oil recovery from oil-wet carbonate rock induced by supply of thermal energy.

  10. Abiotic CO2 reduction during geologic carbon sequestration facilitated by Fe(II)-bearing minerals

    Science.gov (United States)

    Nielsen, L. C.; Maher, K.; Bird, D. K.; Brown, G. E.; Thomas, B.; Johnson, N. C.; Rosenbauer, R. J.

    2012-12-01

    Redox reactions involving subsurface minerals and fluids and can lead to the abiotic generation of hydrocarbons from CO2 under certain conditions. Depleted oil reservoirs and saline aquifers targeted for geologic carbon sequestration (GCS) can contain significant quantities of minerals such as ferrous chlorite, which could facilitate the abiotic reduction of carbon dioxide to n-carboxylic acids, hydrocarbons, and amorphous carbon (C0). If such reactions occur, the injection of supercritical CO2 (scCO2) could significantly alter the oxidation state of the reservoir and cause extensive reorganization of the stable mineral assemblage via dissolution and reprecipitation reactions. Naturally occurring iron oxide minerals such as magnetite are known to catalyze CO2 reduction, resulting in the synthesis of organic compounds. Magnetite is thermodynamically stable in Fe(II) chlorite-bearing mineral assemblages typical of some reservoir formations. Thermodynamic calculations demonstrate that GCS reservoirs buffered by the chlorite-kaolinite-carbonate(siderite/magnesite)-quartz assemblage favor the reduction of CO2 to n-carboxylic acids, hydrocarbons, and C0, although the extent of abiotic CO2 reduction may be kinetically limited. To investigate the rates of abiotic CO2 reduction in the presence of magnetite, we performed batch abiotic CO2 reduction experiments using a Dickson-type rocking hydrothermal apparatus at temperatures (373 K) and pressures (100 bar) within the range of conditions relevant to GCS. Blank experiments containing CO2 and H2 were used to rule out the possibility of catalytic activity of the experimental apparatus. Reaction of brine-suspended magnetite nanoparticles with scCO2 at H2 partial pressures typical of reservoir rocks - up to 100 and 0.1 bars respectively - was used to investigate the kinetics of magnetite-catalyzed abiotic CO2 reduction. Later experiments introducing ferrous chlorite (ripidolite) were carried out to determine the potential for

  11. Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean

    OpenAIRE

    Kennedy, Martin J.; Wagner, Thomas

    2011-01-01

    The majority of carbon sequestration at the Earth’s surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m2 g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% ...

  12. Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery

    Energy Technology Data Exchange (ETDEWEB)

    Faulconer, Emily K., E-mail: emily.faulconer@yahoo.com [Department of Environmental Engineering Sciences, University of Florida, 217 Black Hall, P.O. Box 116450, Gainesville, FL 32611-645 (United States); Hoogesteijn von Reitzenstein, Natalia V.; Mazyck, David W. [Department of Environmental Engineering Sciences, University of Florida, 217 Black Hall, P.O. Box 116450, Gainesville, FL 32611-645 (United States)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Thermal oxidation of MPAC decreased the amorphous characteristic of iron oxides. Black-Right-Pointing-Pointer Thermal oxidation did not influence magnetic recovery or Hg removal performance. Black-Right-Pointing-Pointer At all thermal oxidation temperatures, the 3:1 MPAC achieved the highest Hg removal. - Abstract: Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 {mu}g/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury-carbon contact chamber with mixing and constant N{sub 2} (g) headspace flow to an oxidizing trap. Mercury adsorption was performed using spiked ultrapure water (100 {mu}g/L Hg). Mercury concentrations were obtained using EPA method 245.1 and cold vapor atomic absorption spectroscopy. MPAC synthesis was optimized for Hg removal and sorbent recovery according to the variables: C:Fe, thermal oxidation temperature and time. The 3:1 C:Fe preserved most of the original sorbent surface area. As indicated by XRD patterns, thermal oxidation reduced the amorphous characteristic of the iron oxides but did not improve sorbent recovery and damaged porosity at higher oxidation temperatures. Therefore, the optimal synthesis variables, 3:1 C:Fe mass ratio without thermal oxidation, which can achieve 92.5% ({+-}8.3%) sorbent recovery and 96.3% ({+-}9%) Hg removal. The mass balance has been closed to within approximately {+-}15%.

  13. Glucose-Derived Porous Carbon-Coated Silicon Nanowires as Efficient Electrodes for Aqueous Micro-Supercapacitors.

    Science.gov (United States)

    Devarapalli, Rami Reddy; Szunerits, Sabine; Coffinier, Yannick; Shelke, Manjusha V; Boukherroub, Rabah

    2016-02-24

    In this study, we report on carbon coating of vertically aligned silicon nanowire (SiNWs) arrays via a simple hydrothermal process using glucose as carbon precursor. Using this process, a thin carbon layer is uniformly deposited on the SiNWs. Under optimized conditions, the coated SiNWs electrode showed better electrochemical energy storage capacity as well as exceptional stability in aqueous system as compared to uncoated SiNWs. The as-measured capacitance reached 25.64 mF/cm(2) with a good stability up to 25000 charging/discharging cycles in 1 M Na2SO4 aqueous solution. PMID:26866275

  14. Synthesis of multiwalled carbon nanotubes from bamboo charcoal and the roles of minerals on their growth

    International Nuclear Information System (INIS)

    Multiwalled carbon nanotubes (MWCNTs) were synthesized from bamboo charcoals by chemical vapor deposition in the presence of ethanol vapor. Fresh bamboo culms were first heat treated at 1000–1500 °C to form charcoals. The elemental composition and structure of mineral phases in the bamboo charcoal treated at different temperatures were analyzed. The results showed that Mg2SiO4 and particularly calcium silicate were responsible for the nucleation and growth of MWCNTs at 1200–1400 °C. Transmission electron microscope and energy dispersive X-ray spectrometer observations indicated that the tips of nanotubes synthesized at 1200–1400 °C consist mainly of calcium silicate. Such silicate tips acted as effective catalysts for nanotubes. The growth of MWCNTs followed the vapor–liquid–solid model including an initial decomposition of ethanol vapor into carbon, dissolution of carbon inside molten silicate and final nucleation of nanotubes. -- Graphical abstract: Calcium silicate spheres formed on the surface of the bamboo charcoal after thermal treatments. Multiwalled carbon nanotubes were synthesized by ethanol chemical vapor deposition. The growth of CNTs follows the vapor–liquid–solid mechanism. Uploading of CNTs could increase the specific surface area and the N2 adsorption capacity. Highlights: ► The evolution of minerals in bamboo charcoal under heat treatment is found. ► The roles of minerals in bamboo charcoal in the growth of CNTs are proposed. ► The upload of CNTs increases the specific surface area and the adsorption capacity.

  15. Flue gas CO2 mineralization using thermally activated serpentine: from single- to double-step carbonation.

    Science.gov (United States)

    Werner, Mischa; Hariharan, Subrahmaniam; Mazzotti, Marco

    2014-12-01

    Carbon dioxide capture and utilization by mineralization seeks to combine greenhouse gas emission control with the production of value-added materials in the form of solid carbonates. This experimental work demonstrates that the world's most abundant mineralization precursor, the magnesium (Mg) silicate serpentine, in its thermally activated, partially dehydroxylated form can be carbonated without the use of chemical additives at process temperatures (T) below 90 °C and CO2 partial pressures (pCO2) below 1 bar. A first series of single-step batch experiments was performed varying the temperature and slurry density to systematically assess the precipitation regime of the relevant Mg-carbonates and the fate of silicon (Si) species in solution. The results suggested that the reaction progress was hindered by a passivating layer of re-precipitated silica or quartz, as well as by equilibrium limitations. Concurrent grinding proved effective in tackling the former problem. A double-step strategy proved successful in addressing the latter problem by controlling the pH of the solution. This is achieved by continuously removing the Mg from the dissolution reactor and letting it precipitate at a higher T and a lower pCO2 in a separate reactor, thus yielding a combined T-pCO2-swing-the working principle of a new flue gas mineralization route is presented herein. Simulations and experiments of the different individual steps of the process are reported, in order to make an assessment of its feasibility. PMID:25327589

  16. Kinetics of absorption of carbon dioxide into aqueous potassium salt of proline

    DEFF Research Database (Denmark)

    Paul, Subham; Thomsen, Kaj

    2012-01-01

    with KPr for the above mentioned concentration and temperature range. Following the reaction mechanism of CO2 with primary and secondary alkanolamies, the reaction of CO2 with KPr is also described using zwitterionic mechanism. Based on the pseudo-first-order condition for the CO2 absorption, the......The absorption of carbon dioxide (CO2) into aqueous solution of potassium prolinate (KPr) are studied at 303, 313, and 323K within the salt concentration range of 0.5–3.0kmolm−3 using a wetted wall column absorber. The experimental results are used to interpret the kinetics of the reaction of CO2...

  17. Mercury Removal from Aqueous Solution and Flue Gas by Adsorption on Activated Carbon Fibres

    OpenAIRE

    Nabais, Joao; Carrott, Peter; Ribeiro Carrott, Manuela

    2006-01-01

    The use of two activated carbon fibres, one laboratorial sample prepared from a commercial acrylic textile fibre and one commercial sample of Kynol1, as prepared/received and modified by reaction with powdered sulfur and H2S gas in order to increase the sulfur content were studied for the removal of mercury from aqueous solution and from flue gases from a fluidized bed combustor. The sulfur introduced ranged from 1 to 6 wt.% depending on the method used. The most important parameter ...

  18. Precipitation kinetics of Mg-carbonates, influence of organic ligands and consequences for CO2 mineral sequestration

    International Nuclear Information System (INIS)

    Forming magnesium carbonate minerals through carbonation of magnesium silicates has been proposed as a safe and durable way to store carbon dioxide, with a possibly high potential to offset anthropogenic CO2 emissions. To date however, chemical reactions involved in this process are facing strong kinetic limitations, which originate in the low reactivity of both Mg-silicates and Mg-carbonates. Numerous studies have focused on the dissolution of Mg-silicates, under the questionable hypothesis that this step limits the whole process. This thesis work focuses instead on the mechanisms and rates of formation of magnesium carbonates, which are the final products of carbonation reactions. The first part of the work is dedicated to studying the influence on magnesite precipitation kinetics of three organic ligands known to accelerate Mg-silicates dissolution rates: oxalate, citrate and EDTA. With help of mixed-flow reactor experiments performed between 100 and 150 C, we show that these ligands significantly reduce magnesite growth rates, through two combined mechanisms: (1) complexation of Mg2+ cations in aqueous solution, which was rigorously estimated from a thermodynamic database established through a critical review of the literature, and (2) adsorption of ligands to a limited number of surface sites, leading to a decrease of the precipitation rate constant. The observed growth inhibition is maximal with citrate. We then used hydrothermal atomic force microscopy to probe the origin of the documented growth inhibition. Our observations show that citrate and oxalate interact with the crystal growth process on magnesite surface, modifying the shape of growth hillocks as well as the step generation frequency through spiral growth. We also show that the ligands adsorb preferentially on different kink-sites, which is probably related to their different structures and chemical properties. We propose that the stronger magnesite growth inhibition caused by citrate is related

  19. Precipitation of calcium carbonate in aqueous solutions in presence of ethylene glycol and dodecane.

    Science.gov (United States)

    Natsi, Panagiota D.; Rokidi, Stamatia; Koutsoukos, Petros G.

    2015-04-01

    The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The

  20. Carbon cycling and mineral weathering in the Sava River catchment in Slovenia

    International Nuclear Information System (INIS)

    Global environmental change has been identified as one of the most urgent issues of earth science research. Much research effort has addressed the role of the terrestrial reservoir in modulating carbon storage, and in turn, how the rapid cycling of carbon at the earth's surface over the next few hundreds of years will affect earth's surface environment. The chemical interactions among carbonate minerals (calcite and dolomite), organic carbon and the natural hydrologic cycle link the atmospheric and terrestrial carbon reservoirs on short time scales. Among the minerals comprising surface rocks and soils, only carbonate minerals appear capable of maintaining equilibrium in the face of rising atmospheric CO2 injections from fossil fuel burning. Rapid carbonate mineral weathering reactions also largely regulate the pH and ionic strength of terrestrial aquatic systems and so have ecologic and environmental impacts. We are investigating the geochemical dynamics using major elemental, stable isotope, and hydrogeochemical parameters to better understand carbon mass transport of the Sava river drainages in Slovenia. Importantly, the Sava catchment is the largest catchment in Slovenia and at the same time one of the tributary streams of the Danube river, the second largest river in Europe. The weathering of the Danube river represents one of the largest carbon fluxes in the world. Rock weathering contributes a significant portion of HCO3- - to most rivers and thus has a strong influence on their carbon cycle. First results in the Sava River catchment indicate that the watershed exhibit typical 1:2 ratio of divalent cations to bicarbonate ion consistent with simple carbonate mineral dissolution in pure water. The Mg/Ca mole ratios are higher than 0.5 with 1 mol Ca for 0.5 mol Mg, the ratio predicted for equilibration in systems where calcite and dolomite dissolution proceed together. The concentration of DIC is high in the Sava River and lies well above the average

  1. Nanoscale carbon materials from hydrocarbons pyrolysis: Structure, chemical behavior, utilisation for non-aqueous supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • N-doped and regular carbon nanomaterials were obtained by pyrolitic technique. • Dynamic vapor sorption of different solvents reveals smaller SBET values. • Steric hindrance and specific chemical interactions are the reasons for this. • Nitrogen doping leads to raise of capacitance and coulombic efficiency with non-aqueous N-containing electrolyte. - Abstract: This work systematically studies adsorption properties of carbon nanomaterials that are synthesized through hydrocarbons that is a powerful technique to fabricate different kinds of carbon materials, e.g., nanotubes, nanoshells, onions, including nitrogen substituted. The adsorption properties of the as-synthesized carbons are achieved by low temperature nitrogen adsorption and organic vapors sorption. Heptane, acetonitrile, water, ethanol, benzene and 1-methylimidazole, which are of great importance for development of supercapacitors, are used as substrates. It is discovered that while nitrogen adsorption reveals a high specific surface area, this parameter for most of organic compounds is rather small depending not only on the size of its molecule but also on chemical interactions for a pair adsorbent–adsorbate. The experimental values of heat of adsorption for carbon and N-substituted structures, when Coulomb cross-coupling of nitrogen atoms in adsorbent and adsorbate takes place, confirms this supposition

  2. Nanoscale carbon materials from hydrocarbons pyrolysis: Structure, chemical behavior, utilisation for non-aqueous supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Savilov, Serguei V., E-mail: savilov@chem.msu.ru [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Strokova, Natalia E.; Ivanov, Anton S.; Arkhipova, Ekaterina A. [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Desyatov, Andrey V. [D. Mendeleyev University of Chemical Technology of Russia (Russian Federation); Hui, Xia [Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology (China); Aldoshin, Serguei M. [Lomonosov Moscow State University, Faculty of Fundamental Physical and Chemical Engineering (Russian Federation); Lunin, Valery V. [Lomonosov Moscow State University, Chemistry Department (Russian Federation)

    2015-09-15

    Highlights: • N-doped and regular carbon nanomaterials were obtained by pyrolitic technique. • Dynamic vapor sorption of different solvents reveals smaller S{sub BET} values. • Steric hindrance and specific chemical interactions are the reasons for this. • Nitrogen doping leads to raise of capacitance and coulombic efficiency with non-aqueous N-containing electrolyte. - Abstract: This work systematically studies adsorption properties of carbon nanomaterials that are synthesized through hydrocarbons that is a powerful technique to fabricate different kinds of carbon materials, e.g., nanotubes, nanoshells, onions, including nitrogen substituted. The adsorption properties of the as-synthesized carbons are achieved by low temperature nitrogen adsorption and organic vapors sorption. Heptane, acetonitrile, water, ethanol, benzene and 1-methylimidazole, which are of great importance for development of supercapacitors, are used as substrates. It is discovered that while nitrogen adsorption reveals a high specific surface area, this parameter for most of organic compounds is rather small depending not only on the size of its molecule but also on chemical interactions for a pair adsorbent–adsorbate. The experimental values of heat of adsorption for carbon and N-substituted structures, when Coulomb cross-coupling of nitrogen atoms in adsorbent and adsorbate takes place, confirms this supposition.

  3. Physical and electrochemical characteristics of supercapacitors based on carbide derived carbon electrodes in aqueous electrolytes

    Science.gov (United States)

    Eskusson, Jaanus; Jänes, Alar; Kikas, Arvo; Matisen, Leonard; Lust, Enn

    FIB-SEM, XPS and gas adsorption methods have been used for the characterisation of physical properties of microporous carbide derived carbon electrodes prepared from Mo 2C at 600 °C (noted as CDC-Mo 2C). Cyclic voltammetry, constant current charge/discharge, and electrochemical impedance spectroscopy have been applied to establish the electrochemical characteristics for supercapacitors consisting of the 1 M Na 2SO 4, KOH, tetraethyl ammonium iodide or 6 M KOH aqueous electrolyte and CDC-Mo 2C electrodes. The N 2 sorption values obtained have been correlated with electrochemical characteristics for supercapacitors in various aqueous electrolytes. The maximum gravimetric energy, E max, and gravimetric power, P max, for supercapacitors (taking into consideration the active material weight) have been obtained at cell voltage 0.9 V for 6 M KOH aqueous supercapacitor (E max = 5.7 Wh kg -1 and P max = 43 kW kg -1). For 1 M TEAI based SC somewhat higher E max (6.2 Wh kg -1) and comparatively low P max (7.0 kW kg -1) have been calculated.

  4. Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

    Directory of Open Access Journals (Sweden)

    L. M. Wehrmann

    2008-12-01

    Full Text Available Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.2 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC production, combined with sulfate reduction rates not exceeding 3 nmolS cm−3 d−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in –CH2O– groups and 43% carbon in –CH2– groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Iron reduction linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23-18 GC indicated diagenetic carbonate precipitation. This was consistent

  5. Carbon and nitrogen in forest floor and mineral soil under six common European tree species

    DEFF Research Database (Denmark)

    Vesterdal, Lars; Schmidt, Inger K.; Callesen, Ingeborg;

    2007-01-01

    after planting the six tree species had different profiles in terms of litterfall, forest floor and mineral soil C and N attributes. Three groups were identified: (1) ash, maple and lime, (2) beech and oak, and (3) spruce. There were significant differences in forest floor and soil C and N contents and......The knowledge of tree species effects on soil C and N pools is scarce, particularly for European deciduous tree species. We studied forest floor and mineral soil carbon and nitrogen under six common European tree species in a common garden design replicated at six sites in Denmark. Three decades...... C/N ratios, also among the five deciduous tree species. The influence of tree species was most pronounced in the forest floor, where C and N contents increased in the order ash = lime = maple mineral soil only in some of the sampled soil layers within 30...

  6. Biosorption Studies for the Removal of Malachite Green from its Aqueous Solution by Activated Carbon Prepared from Cassava Peel

    OpenAIRE

    Parvathi, C.; Maruthavanan, T.; S. Sivamani; Prakash, C

    2011-01-01

    The association of dyes with health related problems is not a new phenomenon. The effectiveness of carbon adsorption for dye removal from textile effluent has made it an ideal alternative to other expensive treatment methods. The preparation of activated carbon from agricultural waste could increase economic return and reduce pollution. Cassava peel has been used as a raw material to produce activated carbon. The study investigates the removal of malachite green dye from its aqueous solution....

  7. Removal of insecticide carbofuran from aqueous solutions by banana stalks activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Salman, J.M. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Hameed, B.H., E-mail: chbassim@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2010-04-15

    In this work, activated carbon was prepared from banana stalks (BSAC) waste to remove the insecticide carbofuran from aqueous solutions. The effects of contact time, initial carbofuran concentration, solution pH and temperature (30, 40 and 50 deg. C) were investigated. Adsorption isotherm, kinetics and thermodynamics of carbofuran on BSAC were studied. Equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherm models and the data best represented by the Langmuir isotherm. Thermodynamic parameters such as standard enthalpy ({Delta}H{sup o}), standard entropy ({Delta}S{sup o}) and standard free energy ({Delta}G{sup o}) were evaluated. Regeneration efficiency of spent BSAC was studied using ethanol as a solvent. The efficiency was found to be in the range of 96.97-97.35%. The results indicated that the BSAC has good regeneration and reusability characteristics and can be used as alternative to present commercial activated carbon.

  8. Enabling aqueous binders for lithium battery cathodes - Carbon coating of aluminum current collector

    Science.gov (United States)

    Doberdò, Italo; Löffler, Nicholas; Laszczynski, Nina; Cericola, Dario; Penazzi, Nerino; Bodoardo, Silvia; Kim, Guk-Tae; Passerini, Stefano

    2014-02-01

    In this manuscript a novel approach to enable aqueous binders for lithium ion battery (LIB) cathodes is reported. Producing LiNi1/3Mn1/3Co1/3O2 (NMC) electrodes using sodium-carboxymethylcellulose (CMC) as a binder and water as a solvent, in fact, results in serious aluminum corrosion during electrode manufacturing due to the high pH of the slurry. In order to prevent the direct contact of the corrosive slurry with aluminum foil, the latter is first coated with a thin carbon layer. The CMC-based electrodes formed on carbon coated aluminum foil show enhanced performance than those made using unprotected aluminum instead. In particular, electrodes using protected aluminum foil are able to deliver a capacity of 126 mAh g-1 at 1C rate, which is rather close to that delivered by polyvinylidene-di-fluoride (PVdF)-based electrode having the same composition.

  9. A Review of Spectral Methods for Dispersion Characterization of Carbon Nanotubes in Aqueous Suspensions

    Directory of Open Access Journals (Sweden)

    Jidraph Njuguna

    2015-01-01

    Full Text Available Characterization is a crucial step in the study of properties of nanomaterials to evaluate their full potential in applications. Carbon nanotube-based materials have properties that are sensitive to size, shape, concentration, and agglomeration state. It is therefore critical to quantitatively characterize these factors in situ, while the processing takes place. Traditional characterization techniques that rely on microscopy are often time consuming and in most cases provide qualitative results. Spectroscopy has been studied as an alternative tool for identifying, characterizing, and studying these materials in situ and in a quantitative way. In this paper, we provide a critical review of the spectroscopy techniques used to explore the surface properties (e.g., dispersion characteristics of carbon nanotubes in aqueous suspensions during the sonication process.

  10. RICE BRAN CARBON: AN ALTERNATIVE TO COMMERCIAL ACTIVATED CARBON FOR THE REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    Syed Hadi Hasan

    2010-06-01

    Full Text Available Rice bran carbon (RBC prepared from rice bran (an agricultural waste was successfully utilized for the removal of hexavalent chromium from aqueous solution. The potentiality of RBC was tested and compared with commercial activated carbon (CAC, and it was found that RBC removed 95% of hexavalent chromium at pH 2, 1000 µM Cr(VI concentration, temperature 30 oC, and adsorbent dose of 2 g/L. The maximum uptake of total chromium obtained by applying the Langmuir isotherm model was 138.88 mg/g for RBC, which was found comparable to that obtained by utilizing CAC (116.28 mg/g at 40 oC. The removal of Cr(VI was found maximum at a proton to chromium ratio of 10 and chromium to carbon ratio of 0.052, and these ratios were found to be applicable over a range of Cr(VI concentrations. The removal of Cr(VI, at low pH (< 2.0, was not only due to sorption of Cr(VI but also because of reduction of Cr(VI into less toxic Cr(III, which was also adsorbed on the surface of the sorbent. The rate of reduction removal of Cr(VI followed pseudo-first order kinetics, whereas the sorption of total chromium followed pseudo-second order kinetics for both the types of activated carbons.

  11. Sequestration of carbon dioxide by indirect mineralization using Victorian brown coal fly ash

    International Nuclear Information System (INIS)

    Highlights: ► The indirect CO2 mineralization by brown coal fly ash has been tested. ► A large CO2 capture capacity of fly ash under mild conditions was achieved. ► The kinetic analysis confirmed a fast reaction rate with low activation energy. ► The fly ash based capture process is highly efficient and cost-effective. - Abstract: The use of an industry waste, brown coal fly ash collected from the Latrobe Valley, Victoria, Australia, has been tested for the post-combustion CO2 capture through indirect minersalization in acetic acid leachate. Upon the initial leaching, the majority of calcium and magnesium in fly ash were dissolved into solution, the carbonation potential of which was investigated subsequently through the use of a continuously stirred high-pressure autoclave reactor and the characterization of carbonation precipitates by various facilities. A large CO2 capture capacity of fly ash under mild conditions has been confirmed. The CO2 was fixed in both carbonate precipitates and water-soluble bicarbonate, and the conversion between these two species was achievable at approximately 60 °C and a CO2 partial pressure above 3 bar. The kinetic analysis confirmed a fast reaction rate for the carbonation of the brown coal ash-derived leachate at a global activation energy of 12.7 kJ/mol. It is much lower than that for natural minerals and is also very close to the potassium carbonate/piperazine system. The CO2 capture capacity of this system has also proven to reach maximum 264 kg CO2/tonne fly ash which is comparable to the natural minerals tested in the literature. As the fly ash is a valueless waste and requires no comminution prior to use, the technology developed here is highly efficient and energy-saving, the resulting carbonate products of which are invaluable for the use as additive to cement and in the paper and pulp industry.

  12. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    F. Dehairs

    2004-08-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1 cm typically showed more enriched δ13C values than deeper (up to 10 cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on these results and a compilation of literature data, we suggest that allochtonous carbon trapped in seagrass beds may often represent a significant fraction of the substrate for benthic mineralization - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that community respiration data systematically overestimate the role of mineralization in the overall seagrass C budget.

  13. Mineral Sequestration of Carbon Dixoide in a Sandstone-Shale System

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Apps, John A.; Pruess, Karsten

    2004-07-09

    A conceptual model of CO2 injection in bedded sandstone-shale sequences has been developed using hydrogeologic properties and mineral compositions commonly encountered in Gulf Coast sediments. Numerical simulations were performed with the reactive fluid flow and geochemical transport code TOUGHREACT to analyze mass transfer between sandstone and shale layers and CO2 immobilization through carbonate precipitation. Results indicate that most CO2 sequestration occurs in the sandstone. The major CO2 trapping minerals are dawsonite and ankerite. The CO2 mineral-trapping capacity after 100,000 years reaches about 90 kg per cubic meter of the medium. The CO2 trapping capacity depends on primary mineral composition. Precipitation of siderite and ankerite requires Fe+2 supplied mainly by chlorite and some by hematite dissolution and reduction. Precipitation of dawsonite requires Na+ provided by oligoclase dissolution. The initial abundance of chlorite and oligoclase therefore affects the CO2 mineral trapping capacity. The sequestration time required depends on the kinetic rate of mineral dissolution and precipitation. Dawsonite reaction kinetics is not well understood, and sensitivity regarding the precipitation rate was examined. The addition of CO2 as secondary carbonates results in decreased porosity. The leaching of chemical constituents from the interior of the shale causes slightly increased porosity. The limited information currently available for the mineralogy of natural high-pressure CO2 gas reservoirs is also generally consistent with our simulation. The ''numerical experiments'' give a detailed understanding of the dynamic evolution of a sandstone-shale geochemical system.

  14. Crystal chemical correlations between the mid and near-infrared in carbonate minerals

    Science.gov (United States)

    Hopkinson, Laurence; Rutt, Ken J.

    2016-06-01

    Near-infrared (NIR) spectra of carbonates have proved important in many disciplines including planetary exploration. Classically bands in the 4000-6000 cm- 1 (2.5-1.67 μm) region are assigned to [CO32-] internal mode combinations and overtones. However band assignments remain equivocal. This study examines three prominent bands ((ca 4505 cm- 1 (2.219 μm), 4900 cm- 1 (2.041 μm) and 5145 cm- 1 (1.944 μm)) from powdered calcite and aragonite group minerals. Results indicate that the bands originate from anharmonic coupling of degenerate internal mode(s) with external (lattice) modes. On this basis it is suggested that NIR data may provide an untapped source of detailed information on lattice mode frequencies and information on the type(s) of the environmental cation(s) in carbonate minerals.

  15. The growth of multi-walled carbon nanotubes on natural clay minerals (kaolinite, nontronite and sepiolite)

    International Nuclear Information System (INIS)

    The suitability of clay minerals - kaolinite, nontronite and sepiolite - is studied for synthesis of nanocomposites based on carbon nanotubes. Particles of iron were used as catalysts. Prior to synthesis, kaolinite and sepiolite were doped by the catalytically active metal, whereas in the case of nontronite the presence was used of this metal in the matrix of this mineral. Synthesis of CNTs was performed by hot filament chemical vapor deposition method. The produced nanocomposites were examined by transmission and scanning electron microscopies and energy dispersive X-ray spectroscopy. The experiment verified the potential of the three microcrystalline phyllosilicates for the growth of carbon nanotubes. Under the same technology conditions, the type of catalyst carrier affects the morphology and structure of the nanotube product markedly.

  16. Carbon mineralization and oxygen dynamics in sediments with deep oxygen penetration, Lake Superior

    DEFF Research Database (Denmark)

    Li, Jiying; Crowe, Sean Andrew; Miklesh, David;

    2012-01-01

    To understand carbon and oxygen dynamics in sediments with deep oxygen penetration, we investigated eight locations (160–318-m depth) throughout Lake Superior. Despite the 2–4 weight percent organic carbon content, oxygen penetrated into the sediment by 3.5 to > 12 cm at all locations. Such deep......, suggesting that temporal variability in deeply oxygenated sediments may be greater than previously acknowledged. The oxygen uptake rates (4.4–7.7 mmol m−2 d−1, average 6.1 mmol m−2 d−1) and carbon mineralization efficiency (∼ 90% of deposited carbon) were similar to those in marine hemipelagic and pelagic...... penetration is explained by low sedimentation rates (0.01–0.04 cm yr−1), high solubility of oxygen in freshwater, and a shallow (∼ 2 cm) bioturbation zone. In response mainly to oxygen variations in the bottom waters, the sediment oxygen penetration varied seasonally by as much as several centimeters...

  17. Natural abundance measurements of 13C indicate increased deep soil carbon mineralization after forest disturbance

    Science.gov (United States)

    Diochon, Amanda; Kellman, Lisa

    2008-07-01

    Northern forest soils represent globally important stores of carbon (C), yet there is no consensus about how they are altered by the widespread practice of harvesting that dominates many forested landscapes. Here we present the first study to systematically investigate the utility of δ 13C and C content depth profiles to infer temporal changes in belowground carbon cycling processes following disturbance in a pure C3 ecosystem. We document carbon concentration and δ 13C depth profile enrichment trends consistent with a kinetic fractionation arising from soil organic carbon (SOC) humification across a northern forest chronosequence (1, 15, 45, 80 and 125+ yrs). Reduced soil C storage that coincided with observed soil profile δ 13C-enrichment patterns which intensified following clearcut harvesting, pointed to losses of SOC in the deeper (>20 cm) mineral soil. This study suggests the δ 13C approach may assist in identifying mechanisms responsible for soil C storage changes in disturbed C3 forest ecosystems.

  18. Migration of dissolved organic carbon in biochars and biochar-mineral complexes

    Directory of Open Access Journals (Sweden)

    Yun Lin

    2012-05-01

    Full Text Available The objective of this work was to determine the contribution of dissolved organic carbon (DOC from a biochar mineral complex (BMC, so as to better understand the interactions between DOC, biochar, clay, and minerals during thermal treatment, and the effects of BMC on amended soils. The BMC was prepared by heating a mixture of a H3PO4-treated saligna biochar from Acacia saligna, clays, other minerals, and chicken manure. The BMC was applied to a sandy loam soil in Western Australia, where wheat was grown. Liquid chromatography-organic carbon detection (LC-OCD tests were carried out on water extracts from the untreated biochar, the BMC, the BMC-amended soil, and on a control soil to measure the DOC concentration. LC-OCD tests provide a fingerprint of the DOC, which allows the fractions of DOC to be determined. Thermal processing enhanced the reaction of the A. saligna biochar with manure, clays and minerals, and affected the distribution of the DOC fractions. Notably, the process leads to immobilization of hydrophobic DOC and to an increase in the concentration of low-molecular-weight neutrals in the BMC. The application of the BMC to soil increases the DOC in the amended soil, especially the biopolymer fraction.

  19. Calibrating the ChemCam LIBS for Carbonate Minerals on Mars

    Science.gov (United States)

    Wiens, Roger C.; Clegg, Samuel M.; Ollila, Ann M.; Barefield, James E.; Lanza, Nina; Newsom, Horton E.

    2009-01-01

    The ChemCam instrument suite on board the NASA Mars Science Laboratory (MSL) rover includes the first LIBS instrument for extraterrestrial applications. Here we examine carbonate minerals in a simulated martian environment using the LIDS technique in order to better understand the in situ signature of these materials on Mars. Both chemical composition and rock type are determined using multivariate analysis (MVA) techniques. Composition is confirmed using scanning electron microscopy (SEM) techniques. Our initial results suggest that ChemCam can recognize and differentiate between carbonate materials on Mars.

  20. Adsorption of cadmium from aqueous solutions on sulfurized activated carbon prepared from nut shells

    Energy Technology Data Exchange (ETDEWEB)

    Fouladi Tajar, Amir [Chemical Engineering Department, Amirkabir University of Technology, No.424, Hafez Avenue, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Kaghazchi, Tahereh, E-mail: kaghazch@aut.ac.ir [Chemical Engineering Department, Amirkabir University of Technology, No.424, Hafez Avenue, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Soleimani, Mansooreh [Chemical Engineering Department, Amirkabir University of Technology, No.424, Hafez Avenue, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2009-06-15

    Low-cost activated carbon, derived from nut shells, and its modified sample have been used as replacements for the current expensive methods of removing cadmium from aqueous solutions and waste waters. Adsorption of cadmium onto four kinds of activated carbons has been studied; prepared activated carbon (PAC), commercial activated carbon (CAC), and the sulfurized ones (SPAC and SCAC). The activated carbon has been derived, characterized, treated with sulfur and then utilized for the removal of Cd{sup 2+}. Sulfurizing agent (SO{sub 2} gas) was successfully used in adsorbents' modification process at the ambient temperature. Samples were then characterized and tested as adsorbents of cadmium. Effect of some parameters such as contact time, initial concentration and pH were examined. With increasing pH, the adsorption of cadmium ions was increased and maximum removal, 92.4% for SPAC, was observed in pH > 8.0 (C{sub 0} = 100 mg/L). The H-type adsorption isotherms, obtained for the adsorbents, indicated a favorable process. Adsorption data on both prepared and commercial activated carbon, before and after sulfurization, followed both the Frendlich and Langmuir models. They were better fitted by Frendlich isotherm as compared to Langmuir. The maximum adsorption capacities were 90.09, 104.17, 126.58 and 142.86 mg/g for CAC, PAC, SCAC and SPAC, respectively. Accordingly, surface modification of activated carbons using SO{sub 2} greatly enhanced cadmium removal. The reversibility of the process has been studied in a qualitative manner and it shows that the spent SPAC can be effectively regenerated for further use easily.

  1. Adsorption of cadmium from aqueous solutions on sulfurized activated carbon prepared from nut shells

    International Nuclear Information System (INIS)

    Low-cost activated carbon, derived from nut shells, and its modified sample have been used as replacements for the current expensive methods of removing cadmium from aqueous solutions and waste waters. Adsorption of cadmium onto four kinds of activated carbons has been studied; prepared activated carbon (PAC), commercial activated carbon (CAC), and the sulfurized ones (SPAC and SCAC). The activated carbon has been derived, characterized, treated with sulfur and then utilized for the removal of Cd2+. Sulfurizing agent (SO2 gas) was successfully used in adsorbents' modification process at the ambient temperature. Samples were then characterized and tested as adsorbents of cadmium. Effect of some parameters such as contact time, initial concentration and pH were examined. With increasing pH, the adsorption of cadmium ions was increased and maximum removal, 92.4% for SPAC, was observed in pH > 8.0 (C0 = 100 mg/L). The H-type adsorption isotherms, obtained for the adsorbents, indicated a favorable process. Adsorption data on both prepared and commercial activated carbon, before and after sulfurization, followed both the Frendlich and Langmuir models. They were better fitted by Frendlich isotherm as compared to Langmuir. The maximum adsorption capacities were 90.09, 104.17, 126.58 and 142.86 mg/g for CAC, PAC, SCAC and SPAC, respectively. Accordingly, surface modification of activated carbons using SO2 greatly enhanced cadmium removal. The reversibility of the process has been studied in a qualitative manner and it shows that the spent SPAC can be effectively regenerated for further use easily.

  2. Microbial carbon mineralization in tropical lowland and montane forest soils of Peru

    OpenAIRE

    Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P.; Nottingham, Andrew T.; Stott, Andrew W.; Bardgett, Richard D.; Salinas, Norma; Ccahuana, Adan J.Q.; Meir, Patrick

    2014-01-01

    Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g. ‘positive priming effects’ that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labelled substrates, as surrogates of plant inputs, to soils from ...

  3. Microbial carbon mineralization in tropical lowland and montane forest soils of Peru

    OpenAIRE

    Whitaker, Jeanette; Ostle, Nicholas; McNamara, Niall P.; Nottingham, Andrew T.; Stott, Andrew W.; Bardgett, Richard D.; Salinas, Norma; Ccahuana, Adan J.Q.; Meir, Patrick

    2014-01-01

    Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., “positive priming effects” that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labeled substrates, as surrogates of plant inputs, to soils from a...

  4. Carbon and nitrogen mineralization and persistence of organic residues under conservation and conventional tillage

    OpenAIRE

    Mulvaney, Michael J.; Wood, C.W.; Balkcom, K.S.; D. A. Shannon; Kemble, J.M.

    2010-01-01

    Metadata only record Combining high biomass cover crops with in situ organic mulches may achieve adequate weed control for no-till production, but the persistence and nutrient release rates from cover crops and mulches is unknown. This article describes carbon and nitrogen mineralization rates from three organic mulches (mimosa (Albizia julibrissin Durazz.), lespedeza (Lespedeza cuneata (Dum. Cours.) G. Don)), and oat (Avena sativa L.) straw) and one summer cover crop (soybean (Glycine max...

  5. Mineral Sequestration of Carbon Dixoide in a Sandstone-Shale System

    OpenAIRE

    Xu, Tianfu; Apps, John A.; Pruess, Karsten

    2004-01-01

    A conceptual model of CO2 injection in bedded sandstone-shale sequences has been developed using hydrogeologic properties and mineral compositions commonly encountered in Gulf Coast sediments. Numerical simulations were performed with the reactive fluid flow and geochemical transport code TOUGHREACT to analyze mass transfer between sandstone and shale layers and CO2 immobilization through carbonate precipitation. Results indicate that most CO2 sequestration occurs in the sandstone. The m...

  6. Revisiting carbonate quantification in apatite (bio)minerals: a validated FTIR methodology

    OpenAIRE

    Grunenwald, Anne; Keyser, Christine; Sautereau, Anne-Marie; Crubézy, Eric; Ludes, Bertrand; Drouet, Christophe

    2014-01-01

    International audience Carbonated apatites represent an important class of compounds encountered in many fields including anthropology, archeology, geology, medicine and biomaterials engineering. They constitute, in particular, the mineral part of bones and teeth, are found in sedimentary settings, and are used as biomimetic compounds for the development of bone tissue engineering scaffolds. Whether for assessing the degree of biomimetism of synthetic apatites or for better understanding d...

  7. Factors affecting the precipitation of pure calcium carbonate during the direct aqueous carbonation of flue gas desulfurization gypsum

    International Nuclear Information System (INIS)

    The mineral carbonation of FGD (flue gas desulfurization) gypsum was carried out through CO2 sorption into ammonia solution containing FGD gypsum. High-purity calcium carbonate was precipitated from DCC (dissolved calcium carbonate) solution which was extracted during the induction period. The factors affecting the preparation of pure calcium carbonate were examined under the following conditions: CO2 flow rate (1–3 L/min), ammonia content (4–12%), and S/L (solid-to-liquid) ratio (5–300 g/L). X-Ray diffraction study revealed that the PCC (precipitated calcium carbonate) was round-shaped vaterite. The induction time for PCC decreased as the CO2 flow rate increased. The maximum formation efficiency for pure PCC was seen to increase linearly with the ammonia content. The formation efficiency for pure PCC was the highest (90%) for S/L ratio of 5 g/L but it decreased as S/L ratio increased. On the other hand, S/L ratio didn't affect the maximum solubility limit of DCC. It is believed that the pure PCC would add an economic value to the FGD gypsum carbonation for industrial CO2 sequestration. - Highlights: • Pure and white CaCO3 was synthesized using induction period during direct carbonation of FGD gypsum. • Its formation efficiency was increased with ammonia content but decreased with solid-to-liquid ratio. • This method is expected to extend to other industrial CO2 sequestration for the enhanced economic value of precipitated CaCO3

  8. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    Science.gov (United States)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  9. Aqueous phase adsorption of different sized molecules on activated carbon fibers: Effect of textural properties.

    Science.gov (United States)

    Prajapati, Yogendra N; Bhaduri, Bhaskar; Joshi, Harish C; Srivastava, Anurag; Verma, Nishith

    2016-07-01

    The effect that the textural properties of rayon-based activated carbon fibers (ACFs), such as the BET surface area and pore size distribution (PSD), have on the adsorption of differently sized molecules, namely, brilliant yellow (BY), methyl orange (MO) and phenol (PH), was investigated in the aqueous phase. ACF samples with different BET areas and PSDs were produced by steam-activating carbonized fibers for different activation times (0.25, 0.5, and 1 h). The samples activated for 0.25 h were predominantly microporous, whereas those activated for relatively longer times contained hierarchical micro-mesopores. The adsorption capacities of the ACFs for the adsorbate increased with increasing BET surface area and pore volume, and ranged from 51 to 1306 mg/g depending on the textural properties of the ACFs and adsorbate size. The adsorption capacities of the hierarchical ACF samples followed the order BY > MO > PH. Interestingly, the number of molecules adsorbed by the ACFs followed the reverse order: PH > MO > BY. This anomaly was attributed to the increasing molecular weight of the PH, MO and BY molecules. The equilibrium adsorption data were described using the Langmuir isotherm. This study shows that suitable textural modifications to ACFs are required for the efficient aqueous phase removal of an adsorbate. PMID:27107386

  10. Mineral CO2 sequestration in basalts and ultra-basic rocks: impact of secondary silicated phases on the carbonation process

    International Nuclear Information System (INIS)

    The formation of carbonates constitutes a stable option for carbon dioxide (CO2) geological sequestration, and is prone to play a significant role in reducing emissions of anthropic origin. However, our comprehension of the carbonation mechanism, as well as of the kinetics limitations encountered during this chemical reaction, remains poorly developed. Though there is a large number of studies focusing on the dissolution kinetics of basic silicates and on the precipitation of carbonates, few have inquired about the impact that the formation of non-carbonated secondary phases can have on these reaction's kinetics. It is the approach chosen here, as only solid knowledge of the global carbonation mechanism can make this process predictive and efficient. Experimental data on dissolution and carbonation have therefore been determined in batch reactors, on relevant minerals and rocks. Firstly, we studied the carbonation of olivine (a major phase within peridotites and minor within basalts) at 90 deg. C and under pCO2 of 280 bars. The dissolution of San Carlos olivine (Mg1.76Fe0.24SiO4) is slowed down by the formation of a surface silica gel, when the fluid reaches equilibrium with amorphous silica. The transport of species to the reactive medium becomes the limiting step of the process, slowing down the dissolution process of San Carlos olivine by 5 orders of magnitude. However, this passivation doesn't occur during the alteration of Ca-olivine (Ca2SiO4), though a surface silica layer does form. This comparison suggests that it isn't the structure of the silicate but its chemical composition, which controls the transport properties through the interfacial layer. The second part explores the effects of organic ligands and of temperature variations on the formation of those phases. The addition of citrate at 90 deg. C increases the kinetics of San Carlos olivine by one order of magnitude, and allows the release of enough Mg in the aqueous medium to form carbonates, before

  11. Olivine alteration and H2 production in carbonate-rich, low temperature aqueous environments

    Science.gov (United States)

    Neubeck, Anna; Duc, Nguyen Thanh; Hellevang, Helge; Oze, Christopher; Bastviken, David; Bacsik, Zoltán; Holm, Nils G.

    2014-06-01

    Hydrous alteration of olivine is capable of producing molecular hydrogen (H2) under a wide variety of hydrothermal conditions. Although olivine hydrolysis (i.e., serpentinization) has commonly been assessed at elevated temperatures (>100 °C), the nature of these reactions in relation to H2 production at lower temperatures has not been systematically evaluated, especially with regard to carbonate-rich fluids. Specifically, carbonate formation may kinetically infringe on geochemical routes related to serpentinization and H2 production at lower temperatures. Here time-dependent interactions of solid, liquid, and gaseous phases with respect to olivine hydrolysis in a carbonate-rich solution (20 mM HCO3-) at 30, 50 and 70 °C for 315 days is investigated experimentally. Within the first two months, amorphous Si-rich (i.e., talc-like) and carbonate phases precipitated; however, no inhibition of olivine dissolution is observed at any temperature based on surface chemistry analyses. High-resolution surface analyses confirm that precipitates grew as spheroids or vertically to form topographic highs allowing further dissolution of the free olivine surfaces and exposing potential catalysts. Despite no magnetite (Fe3O4) being detected, H2 increased with time in experiments carried out at 70 °C, indicating an alternative coupled route for Fe oxidation and H2 production. Spectrophotometry analyses show that aqueous Fe(II) is largely converted to Fe(III) potentially integrating into other phases such as serpentine and talc, thus providing a viable pathway for H2 production. No increase in H2 production was observed in experiments carried out at 30 and 50 °C supporting observations that incorporation of Fe(II) into carbonates occurred faster than the intertwined processes of olivine hydrolysis and Fe(III) oxidation. Overall, carbonate formation is confirmed to be a major influence related to H2 production in low-temperature serpentinization systems. We studied low temperature

  12. Carbon-13 NMR characterization of actinyl(VI) carbonate complexes in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D.L.; Hobart, D.E.; Palmer, P.D. [Los Alamos National Lab., NM (United States); Sullivan, J.C. [Argonne National Lab., IL (United States); Stout, B.E. [Cincinnati Univ., OH (United States). Dept. of Chemistry

    1992-07-01

    The uranyl(VI) carbonate system has been re-examined using {sup 13}C NMR of 99.9% {sup 13}C-enriched U{sup VI}O{sub 2} ({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} in millimolar concentrations. By careful control of carbonate ion concentration, we have confirmed the existence of the trimer, and observed dynamic equilibrium between the monomer and the timer. In addition, the ligand exchange reaction between free and coordinated carbonate on Pu{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} and Am{sup VI}O{sub 2}({sup 13}CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR line-broadening techniques {sup 13}C NMR line-broadening techniques. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was written to allow for experimental determination of ligand exchange parameters for paramagnetic actinide complexes. Preliminary Eyring analysis has provided activation parameters of {Delta}G{sup {double_dagger}}{sub 295} = 56 kJ/M, {Delta}H{sup {double_dagger}} = 38 kJ/M, and {Delta}S{sup {double_dagger}} = {minus}60 J/M-K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl (VI) carbonate complex self-exchange reaction. Experiments for determination of the activation parameters for the americium (VI) carbonate system are in progress.

  13. Priming effects of leaves of Laurus nobilis L. and 1,8-cineole on carbon mineralization

    Directory of Open Access Journals (Sweden)

    Burak Kocak

    2016-03-01

    Full Text Available Plant secondary compounds can have stimulating effect on C cycling and change its rate in soils. We examined how leaves of bay laurel (Laurus nobilis L.; Lauraceae and 1,8-cineole (CIN, one of its constituents, affect soil C mineralization and its rate. Leaves and soil samples of bay laurel were taken from Cukurova University Campus (Adana, Turkey growing naturally under Mediterranean climate conditions. Leaves and CIN were considered as the two forms of organic C sources. After determining the level of 1,8-cineole in leaves by gas chromatography-mass spectrometry, soils were mixed with powdered leaves and 1,8-cineole based on their C contents at same and half doses of soil organic C level. Carbon mineralization of all soils was determined over 54 d (28 °C, 80% field capacity. While 1,8-cineole was found as a major constituent of leaves (65% of essential oil, all doses of leaves and CIN increased soil microbial activity. There were significant differences for C mineralization rate between control and all applications (P < 0.05. High C levels of all treatments decreased C mineralization rate compared to control soils. In summary, all treatments stimulated C mineralization and it is possible to conclude that soil microorganisms adapted to use CIN as an energy source.

  14. Pulse electrodeposition of Pt and Pt–Ru methanol-oxidation nanocatalysts onto carbon nanotubes in citric acid aqueous solutions

    International Nuclear Information System (INIS)

    In this study, platinum nanoparticle/carbon nanotube (Pt NP/CNT) and platinum–ruthenium nanoparticle (Pt–Ru NP/CNT) hybrid nanocatalysts were prepared by the pulse-electrodeposition method in different aqueous solutions containing citric acid (CA) or sulfuric acid (SA). The electrocatalytic properties of the Pt NP/CNT and Pt–Ru NP/CNT electrodes prepared using different aqueous solutions were investigated for methanol oxidation. The results show that the electrochemical mass activities of these hybrid nanocatalysts prepared in the CA aqueous solution were increased by factors of 1.46 and 2.77 for Pt NPs and Pt–Ru NPs, respectively, compared with those prepared in SA aqueous solutions using the same procedure. These increased mass activities are attributed to the CA playing dual roles as both a stabilizing agent and a particle size reducing agent in the aqueous solutions. The approach developed in this work enables further reductions in the particle sizes of noble-metal nanocatalysts. - Highlights: • Pulse-electrodeposition of Pt or Pt–Ru nanoparticles on carbon nanotubes • Carbon nanotubes used as a catalyst-supporting material • Citric acid used as reducing agent in the aqueous electrodeposition solutions • Electrochemical activity for methanol oxidation improved by a factor of 1.46 to 2.77

  15. Mineral Soil Carbon in Managed Hardwood Forests of the Northeastern US

    Science.gov (United States)

    Vario, C.; Friedland, A.; Hornig, C.

    2013-12-01

    New England is characterized by extensive forest cover and large reservoirs of soil carbon (C). In northern hardwood forests, mineral soil C can account for up to 50% of total ecosystem C. There has been an increasing demand for forests to serve both as a C sink and a renewable energy source, and effective management of the ecosystem C balance relies on accurate modeling of each compartment of the ecosystem. However, the dynamics of soil C storage with respect to forest use are variable and poorly understood, particularly in mineral soils. For example, current regional models assume C pools after forest harvesting do not change, while some studies suggest that belowground mineral soil C pools can be affected by disturbances at the soil surface. We quantified mineral soil C pools in previously clear-cut stands in seven research or protected forests across New York, New Hampshire, Massachusetts, and Vermont. The ages of the sites sampled ranged from recently cleared to those with no disturbance history, with 21 forest stands represented in the study. Within each research forest studied, physical parameters such as soil type, forest type, slope and land-use history (aside from forest harvest) did not vary between the stands of different ages. Soil samples were collected to a depth of 60 cm below the mineral-organic boundary using a gas-powered augur and 9.5-cm diameter drill bit. Samples were collected in 10-cm increments in shallow mineral soil and 15-cm increments from 30-60 cm depth. Carbon, nitrogen (N), pH, texture and soil mineralogy were measured across the regional sites. At Bartlett Experimental Forest (BEF) in New Hampshire, mineral soil biogeochemistry in cut and uncut sites was studied at a finer scale. Measurements included soil temperature to 55 cm depth, carbon compound analyses using Py-GCMS and soil microbial messenger RNA extractions from mineral soil. Finally, we simulated C dynamics after harvesting by building a model in Stella, with a particular

  16. Role of the surface chemistry of activated carbons in dye removal from aqueous solution

    Science.gov (United States)

    Zhou, Hua-lei; Zhen, Wen-juan; Zhu, Qian; Wu, Xiao-bin; Chang, Zhi-dong; Li, Wen-jun

    2015-07-01

    Commercial activated carbons were modified by a series of chemical or physical treatments using H2O2, NH3, and heating under N2 flow without notably changing their pore structures. The resultant carbons were characterized by N2 adsorption and Bohem titration and then used to remove Ponceau 4R, methyl orange and brilliant blue from aqueous solutions. Surface chemistry was found to play a significantly different role in removing these three compounds. The removal of anionic Ponceau 4R increases with increasing carbon surface basicity due to the predominant dispersive interaction mechanism. In contrast, surface chemistry has little effect on the removal of anionic methyl orange, which can be explained by two parallel mechanisms involving electrostatic and dispersive interactions due to the basic amine group in a dye molecule. The influence of surface chemistry on the removal of amphoteric brilliant blue dye can also be ignored due to a weak interaction between the carbons and dye molecules, which is resulted from strong cohesive energy from electrostatic forces inside amphoteric dye molecules.

  17. Carbonation of Artificial Silicate Minerals in Soils: Passive Removal of Atmospheric CO2

    Science.gov (United States)

    Washbourne, C.; Renforth, P.; Manning, D. A.

    2010-12-01

    Sequestration of CO2 in global soils is a widely recognised phenomenon, which is amenable to an environmental engineering approach. It is proposed that the use of direct soil engineering, promoting CO2 sequestration by accelerating the activity of reactive mineral substrates, has the potential to harness the significant carbon turnover of the global pedologic system (75 x 10^15 gC/yr [1]) [2][3][4]. Estimates of C capture potential through this process are 100-1000 MTa-1. This study focuses on the ambient carbonation of high-Ca residues as agents of mineral CCS. A synergy of contemporary field observations is presented, alongside data acquired from laboratory testing (acid digestion, optical petrography, SEM, IRMS) of carbonated material recovered from urban brown-field and former industrial sites in north east England. It is demonstrated that urban soils may accumulate ~30 kg/m2 (300 T/ha) of carbon over 10 years as inorganic calcium carbonate, approximately twice the typical organic C content of rural soils, ~17.5 kg/m2 in the UK. Stable isotope data (δ13C and δ18O) confirm that over 90% of the carbon is derived from the atmosphere. Economic and mechanical constraints on experimental performance in industrial batch reactor settings have strongly influenced the contemporary view on the efficacy of mineral CCS for large-scale environmental application [5][6][7]. Effective, low-energy field-scale implementation of mineral CCS through soil engineering would counter many of these concerns. Proof of principle for carbon capture efficacy of artificial silicates in soil engineering has been demonstrated [4]; proof of field scale feasibility will be demonstrated though continuing empirical field observation, engineered field cell construction and laboratory investigation. [1] Schlesinger, W. H., et al. (2000), Biogeochemistry, Vol. 48: 7-20. [2] Lal, R. (2003), Critical Reviews in Plant Sciences, 22, pp. 151-184. [3] Manning, D. A. C., (2008), Mineralogical Magazine

  18. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

    Science.gov (United States)

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-01

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm-2 at the current density of 6 mA cm-2 in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (~15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ~88% of the capacitance when the charging rate increased from 6 to 48 mA cm-2. Moreover, the activated CC electrode exhibited excellent cycling stability with ~97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm-2. A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors.Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as

  19. Factors contributing to the formation of carbonated mineral water systems in Serbia

    Directory of Open Access Journals (Sweden)

    Marinković Goran

    2012-01-01

    Full Text Available There are more than 65 occurrences of carbonated mineral water (CMW within the territory of Serbia. More than 93 % of these systems are found in the geotectonic unit referred to as the Vardar Zone and on the fringes of nearby units. To the east, west and north of the Vardar Zone, CMWs are either rare or nonexistent. The area featuring CMWs is characterized by Tertiary magmatism, a complex geology and deep neotectonic structures. Based on δ13C values of CO2 and HCO3 - in several CMWs in Serbia, and also in carbonates and CO2 from liquid inclusions in several hydrothermal deposits around the world, it was concluded that CO2 in the lithosphere of Serbia could originate from hydrothermal carbonates, and carbonates from sedimentary, metamorphic and magmatic rocks. The findings clearly showed that the main generators of CO2 are located in the Vardar Zone and that CO2 degasification is accomplished through temperature metamorphosis of carbonates (dolomite, calcite. Based on the carbonate transformation temperatures and the temperature conditions in the lithosphere of Serbia, the CO2 might be the result of temperature-induced carbonate transformation below a depth of 3 km. Therefore, the conclusion of the study of CMWs in Serbia is that the formation of CMW systems in the lithosphere depends on the geochemical, temperature, and the magmatic and structural-neotectonic conditions.

  20. Microbial and Chemical Enhancement of In-Situ Carbon Mineralization in Geological Formation

    Energy Technology Data Exchange (ETDEWEB)

    Matter, J.; Chandran, K.

    2013-05-31

    Predictions of global energy usage suggest a continued increase in carbon emissions and rising concentrations of CO{sub 2} in the atmosphere unless major changes are made to the way energy is produced and used. Various carbon capture and storage (CCS) technologies are currently being developed, but unfortunately little is known regarding the fundamental characteristics of CO{sub 2}-mineral reactions to allow a viable in-situ carbon mineralization that would provide the most permanent and safe storage of geologically-injected CO{sub 2}. The ultimate goal of this research project was to develop a microbial and chemical enhancement scheme for in-situ carbon mineralization in geologic formations in order to achieve long-term stability of injected CO{sub 2}. Thermodynamic and kinetic studies of CO{sub 2}-mineral-brine systems were systematically performed to develop the in-situ mineral carbonation process that utilizes organic acids produced by a microbial reactor. The major participants in the project are three faculty members and their graduate and undergraduate students at the School of Engineering and Applied Science and at the Lamont-Doherty Earth Observatory at Columbia University: Alissa Park in Earth and Environmental Engineering & Chemical Engineering (PI), Juerg Matter in Earth and Environmental Science (Co-PI), and Kartik Chandran in Earth and Environmental Engineering (Co-PI). Two graduate students, Huangjing Zhao and Edris Taher, were trained as a part of this project as well as a number of graduate students and undergraduate students who participated part-time. Edris Taher received his MS degree in 2012 and Huangjing Zhao will defend his PhD on Jan. 15th, 2014. The interdisciplinary training provided by this project was valuable to those students who are entering into the workforce in the United States. Furthermore, the findings from this study were and will be published in referred journals to disseminate the results. The list of the papers is given at

  1. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance.

    Science.gov (United States)

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-21

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm(-2) at the current density of 6 mA cm(-2) in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (∼15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ∼88% of the capacitance when the charging rate increased from 6 to 48 mA cm(-2). Moreover, the activated CC electrode exhibited excellent cycling stability with ∼97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm(-2). A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors. PMID:27141910

  2. Adsorption of copper, lead and cadmium from aqueous solutions by activated carbon prepared from saffron leaves

    Directory of Open Access Journals (Sweden)

    Shidvash Dowlatshahi

    2014-11-01

    Full Text Available Background: Industrial development has caused the release of various pollutants including heavy metals into the environment. These toxic compounds are extremely dangerous to living beings and the environment due to their non-biodegradability, severe toxicity, carcinogenicity, the ability to be accumulated in nature and the ability to contaminate groundwater and surface water. The aim of the present research was to provide an appropriate and cost-effective adsorbent to remove heavy metals from aqueous solutions. Methods: The activated carbon was produced from the dried. Batch experiments were performed on real and synthetic samples at room temperature. The effect of pH, adsorbent dose, initial concentration, and contact time were studied, and the adsorption isotherms of heavy metals were determined. The removal efficiency was evaluated on real wastewater. Results: The maximum removal efficiency of heavy metals (copper, cadmium and lead by activated carbon adsorbent prepared from saffron leaves was obtained in pH 7. The optimum amount of adsorbent was 0.6 g, and the optimum contact times were 45 min for copper and cadmium ions and 90 min for lead ion, respectively. In these optimum conditions the removal efficiencies were 76.36%, 91.25% and 97.5%, respectively. The removal efficiencies of heavy metals from actual samples (copper industry and the battery industry in the optimum conditions were 82.25%, 69.95% and 91.23%, respectively. The results obtained showed the highest correlation with Langmuir isotherm model. Conclusion: Based on the results obtained, the activated carbon produced from saffron leaves has a good capability in removal of the metal ions from the aqueous solutions. Considering the availability of saffron leaves in Khorasan, its cost-effectiveness, and high uptake capacity, it can be applied as a proper absorbent to remove the heavy metals from industrial wastewater.

  3. Redistributed water by saprotrophic fungi triggers carbon mineralization in dry soils

    Science.gov (United States)

    Guhr, Alexander; Borken, Werner; Matzner, Egbert

    2015-04-01

    Summer droughts are common in temperate forests and especially the upper soil horizons experience soil drought. Drought events can be accompanied by negative effects for forest ecosystems but many plants can reduce drought stress by hydraulic redistribution (HR). Similar processes were recently described for ectomycorrhizal networks but no information is available for mycelia networks of saprotrophic fungi. They strongly contribute to belowground nutrient cycling, C and N mineralization. We hypothesize that redistributed water by saprotrophic fungi triggers mineralization of organic matter in soils under drought conditions. The impact of HR by saprotrophic fungi on mineralization was determined using mesocosms comprising two chambers, separated by a 2 mm air gap to prevent bulk flow of water. After inoculation with fungal cultures and a growth phase, both chambers were desiccated. Subsequently, only chamber I was rewetted while chamber II was treated with 13C labelled plant material. CO2 samples were collected over 7 days after rewetting and analyzed for stable isotope ratio. In addition, enzymatic activity of chitinases and cellobiohydrolases in chamber II was determined after 7 days using the soil zymographie method with fluorogenic 4-Methylumbelliferyl-substrates. A negative control was provided by mesocosms in which hyphal connections between the chambers were severed before rewetting. Intact fungal connections between the chambers led to a strong increase in volumetric water content in chamber II after rewetting of chamber I and the CO2 had a higher enrichment in 13C than in the control mescosms with severed connections. Enrichment started 48 h after rewetting and continued for the rest of the experiment. This resulted in a more than two fold higher total carbon mineralization after 7 days in chamber II of mesocosms with intact hyphal connections. In addition, enzyme activities were also strongly increased compared to controls. In conclusion, mycelia networks

  4. Synthesis and Electrochemical Properties of Al doped Lithium Manganate Powders by Spray Pyrolysis Using Carbonate Aqueous Solution

    OpenAIRE

    HIROSE, Shoji; KODERA, Takayuki; Ogihara, Takashi

    2011-01-01

    Al doped LiMn2O4 powders were prepared by spray pyrolysis using the aqueous solution ofmanganese carbonate. The aqueous solution, in which manganese carbonate was uniformly dispersedby a surfactant, was used as the starting solution. Al2O3 nanopowders, Al(OH)3 and Al(NO3)3·9H2Owere used as the doping agent of Al. A scanning electron microscope photograph showed that Aldoped LiMn2O4 powders had spherical morphology with broad particle size distribution. X-raydiffraction revealed that crystal p...

  5. CO2 Energy Reactor - Integrated Mineral Carbonation: Perspectives on Lab-Scale Investigation and Products Valorization

    Directory of Open Access Journals (Sweden)

    Rafael M Santos

    2016-02-01

    Full Text Available To overcome the challenges of mineral CO2 sequestration, Innovation Concepts B.V. is developing a unique proprietary Gravity Pressure Vessel (GPV reactor technology, and has focussed on generating reaction products of high economic value. The GPV provides intense process conditions through hydrostatic pressurization and heat exchange integration that harvests exothermic reaction energy, thereby reducing energy demand of conventional reactor designs, in addition to offering other benefits. In this paper, a perspective on the status of this technology and outlook for the future is provided. To date, laboratory-scale tests of the envisioned process have been performed in a tubular rocking autoclave reactor. The mineral of choice has been olivine (~Mg1.6Fe2+0.4(SiO4 + ppm Ni/Cr, although asbestos, steel slags and oil shale residues are also under investigation. The effect of several process parameters on reaction extent and product properties have been tested: CO2 pressure, temperature, residence time, additives (buffers, lixiviants, chelators, oxidizers, solids loading, and mixing rate. The products (carbonates, amorphous silica and chromite have been physically separated (based on size, density and magnetic properties, characterized (for chemistry, mineralogy and morphology and tested in intended applications (as pozzolanic carbon-negative building material. Economically, it is found that product value is the main driver for mineral carbonation, rather than, or in addition to, the sequestered CO2. The approach of using a GPV and focusing on valuable reaction products could thus make CO2 mineralization a feasible and sustainable industrial process.

  6. Differential controls on soil carbon density and mineralization among contrasting forest types in a temperate forest ecosystem

    OpenAIRE

    Ye-Ming You; Juan Wang; Xiao-Lu Sun; Zuo-Xin Tang; Zhi-Yong Zhou; Osbert Jianxin Sun

    2016-01-01

    Understanding the controls on soil carbon dynamics is crucial for modeling responses of ecosystem carbon balance to global change, yet few studies provide explicit knowledge on the direct and indirect effects of forest stands on soil carbon via microbial processes. We investigated tree species, soil, and site factors in relation to soil carbon density and mineralization in a temperate forest of central China. We found that soil microbial biomass and community structure, extracellular enzyme a...

  7. Mineralization and carbon turnover in subarctic heath soil as affected by warming and additional litter

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Baath, Erland;

    2007-01-01

    carbon turnover (measured as changes in the pools during a growing-season-long field incubation of soil cores in situ). The mainly N limited bacterial communities had shifted slightly towards limitation by C and P in response to seven growing seasons of warming. This and the significantly increased...... bacterial growth rate under warming may partly explain the observed higher C loss from the warmed soil. This is furthermore consistent with the less dramatic increase in the contents of dissolved organic carbon (DOC) and dissolved organic N (DON) in the warmed soil than in the soil from ambient temperature...... during the field incubation. The added litter did not affect the carbon content, but it was a source of nutrients to the soil, and it also tended to increase bacterial growth rate and net mineralization of P. The inorganic N pool decreased during the field incubation of soil cores, especially in the...

  8. Snow Impurities on Central Asian Glaciers: Mineral Dust, Organic & Elemental Carbon

    Science.gov (United States)

    Schmale, J.; Kang, S.; Peltier, R.; Sprenger, M.; Guo, J.; Li, Y.; Zhang, Q.

    2014-12-01

    In Central Asia, 90 % of the population depend on water stored in glaciers and mountain snow cover. Accelerated melting can be induced by the deposition of e.g., mineral dust and black carbon that reduce the surface albedo. Data on source regions and chemical characteristics of snow impurities are however scarce in Central Asia. We studied aerosol deposited between summers of 2012 and 2013on three different glaciers in the Kyrgyz Republic. Samples were taken from two snow pits on the glacier Abramov in the northern Pamir and from one snow pit on Ak-Shiirak and Suek in the central Tien Shan. The snow was analyzed for elemental and total organic carbon, major ions and mineral dust. In addition, dissolved organic carbon was speciated by using the Aerodyne high-resolution time-of-flight aerosol spectrometer. Elevated mineral dust concentrations were found on all glaciers during summer and winter with lower annual average concentrations (20 mg l-1)in the northern Pamir (factor 5 to 6). Correlations between dust tracers varied, indicating different source regions. Average EC concentrations showed seasonal variation in the northern Pamir (> 100 μg l-1 in summer, 12) than in summer (glaciers ranged between 0.65 and 1.09, indicating a high degree of oxygenation which suggests long-range transport of the organic snow impurities. Marker substances such as potassium and mercury and their correlations suggest contribution from biomass burning emissions. Atmospheric measurements in August 2013 were conducted to obtain information on background aerosol characteristics in the remote high mountain areas. The average black carbon concentration was 0.26 μg/m³ (± 0.24 μg/m³).

  9. Sequestration of carbon dioxide by indirect mineralization using Victorian brown coal fly ash.

    Science.gov (United States)

    Sun, Yong; Parikh, Vinay; Zhang, Lian

    2012-03-30

    The use of an industry waste, brown coal fly ash collected from the Latrobe Valley, Victoria, Australia, has been tested for the post-combustion CO(2) capture through indirect minersalization in acetic acid leachate. Upon the initial leaching, the majority of calcium and magnesium in fly ash were dissolved into solution, the carbonation potential of which was investigated subsequently through the use of a continuously stirred high-pressure autoclave reactor and the characterization of carbonation precipitates by various facilities. A large CO(2) capture capacity of fly ash under mild conditions has been confirmed. The CO(2) was fixed in both carbonate precipitates and water-soluble bicarbonate, and the conversion between these two species was achievable at approximately 60°C and a CO(2) partial pressure above 3 bar. The kinetic analysis confirmed a fast reaction rate for the carbonation of the brown coal ash-derived leachate at a global activation energy of 12.7 kJ/mol. It is much lower than that for natural minerals and is also very close to the potassium carbonate/piperazine system. The CO(2) capture capacity of this system has also proven to reach maximum 264 kg CO(2)/ton fly ash which is comparable to the natural minerals tested in the literature. As the fly ash is a valueless waste and requires no comminution prior to use, the technology developed here is highly efficient and energy-saving, the resulting carbonate products of which are invaluable for the use as additive to cement and in the paper and pulp industry. PMID:22326240

  10. Pb2+ adsorption from aqueous solutions on activated carbons obtained from lignocellulosic residues

    Directory of Open Access Journals (Sweden)

    L. Giraldo

    2008-03-01

    Full Text Available Activated carbons obtained from cane sugar bagasse (ACB, African palm pit (ACP and sawdust (ACS were prepared through an impregnated with HNO3 and thermal treatment in an atmosphere in N2/steam water at 1173 K. Adsorption isotherms of N2 at 77 K and of CO2 at 273 K were determined for the activated carbons for which surface area and pore volume values were from 868 to 1100 m²g-1 and from 0.27 to 0.55cm³ g-1, respectively. These results were correlated, with the ones obtained for adsorption the adsorption isotherms of Pb2+ in aqueous solutions. Impregnation of the lignocellulosic materials with nitric acid produced acid-type activated carbons with total acid site contents between 4.13 and 6.93 mmol g-1 and pH at the point of zero charge values between 2.7 and 4.1, which were within range of the adsorption, at different pH values, since they determined, the surface charge of the activated carbons. Adsorption isotherms of Pb2+ at different pH values (2-8 at 298 K were determined. The ion adsorption capacity on ACB, ACP and ACS were 13.7, 15.2 and 17.5 mg.g-1, respectively. Experimental data were fitted to the Langmuir and Freundlich models and all cases the former fit better. The highest values for the quantity adsorbed on the monolayer, qm, were at pH 4, whereas the surface, charge of activated carbons was negative and the lead species mainly present was Pb2+. For higher pHs, the quantity of Pb2+ adsorbed decreased, and this had an important effect on adsorption, the surface characteristics of the solids and the hydroxilated lead species that were formed in the system.

  11. CarbFix I: Rapid CO2 mineralization in basalt for permanent carbon storage

    Science.gov (United States)

    Matter, J. M.; Stute, M.; Snæbjörnsdóttir, S.; Gíslason, S. R.; Oelkers, E. H.; Sigfússon, B.; Gunnarsson, I.; Aradottir, E. S.; Gunnlaugsson, E.; Broecker, W. S.

    2015-12-01

    Carbon dioxide mineralization via CO2-fluid-rock reactions provides the most permanent solution for geologic CO2 storage. Basalts, onshore or offshore, have the potential to store million metric tons of CO2 as (Ca, Mg, Fe) carbonates [1, 2]. However, as of today it was unclear how fast CO2 is converted to carbonate minerals in-situ in a basalt storage reservoir. The CarbFix I project in Iceland was designed to verify in-situ CO2 mineralization in basaltic rocks. Two injection tests were performed at the CarbFix I pilot injection site near the Hellisheidi geothermal power plant in 2012. 175 tons of pure CO2 and 73 tons of a CO2+H2S mixture were injection from January to March 2012 and in June 2013, respectively. The gases were injected fully dissolved in groundwater into a permeable basalt formation between 400 and 800 m depth using a novel CO2 injection system. Using conservative (SF6, SF5CF3) and reactive (14C) tracers, we quantitatively monitor and detect dissolved and chemically transformed CO2. Tracer breakthrough curves obtained from the first monitoring well indicate that the injected solution arrived in a fast short pulse and a late broad peak. Ratios of 14C/SF6, 14C/SF5CF3 or DIC/SF6 and DIC/SF5CF3 are significantly lower in the monitoring well compared to the injection well, indicating that the injected dissolved CO2 reacted. Mass balance calculations using the tracer data reveal that >95% of the injected CO2 has been mineralized over a period of two years. Evidence of carbonate precipitation has been found in core samples that were collected from the storage reservoir using wireline core drilling as well as in and on the submersible pump in the monitoring well. Results from the core analysis will be presented with emphasis on the CO2 mineralization. [1] McGrail et al. (2006) JGR 111, B12201; [2] Goldberg et al. (2008) PNAS 105(29), 9920-9925.

  12. Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

    Science.gov (United States)

    Fu, Qi; Socki, R. A.; Niles, Paul B.

    2011-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

  13. Removal of organic contaminants from aqueous solution by cattle manure compost (CMC) derived activated carbons

    International Nuclear Information System (INIS)

    The activated carbons (ACs) prepared from cattle manure compost (CMC) with various pore structure and surface chemistry were used to remove phenol and methylene blue (MB) from aqueous solutions. The adsorption equilibrium and kinetics of two organic contaminants onto the ACs were investigated and the schematic models for the adsorptive processes were proposed. The result shows that the removal of functional groups from ACs surface leads to decreasing both rate constants for phenol and MB adsorption. It also causes the decrement of MB adsorption capacity. However, the decrease of surface functional groups was found to result in the increase of phenol adsorption capacity. In our schematic model for adsorptive processes, the presence of acidic functional groups on the surface of carbon is assumed to act as channels for diffusion of adsorbate molecules onto small pores, therefore, promotes the adsorption rate of both phenol and MB. In phenol solution, water molecules firstly adsorb on surface oxygen groups by H-bonding and subsequently form water clusters, which cause partial blockage of the micropores, deduce electrons from the π-electron system of the carbon basal planes, hence, impede or prevent phenol adsorption. On the contrary, in MB solution, the oxygen groups prefer to combine with MB+ cations than water molecules, which lead to the increase of MB adsorption capacity.

  14. Lead and copper removal from aqueous solutions using carbon foam derived from phenol resin.

    Science.gov (United States)

    Lee, Chang-Gu; Jeon, Jun-Woo; Hwang, Min-Jin; Ahn, Kyu-Hong; Park, Chanhyuk; Choi, Jae-Woo; Lee, Sang-Hyup

    2015-07-01

    Phenolic resin-based carbon foam was prepared as an adsorbent for removing heavy metals from aqueous solutions. The surface of the produced carbon foam had a well-developed open cell structure and the specific surface area according to the BET model was 458.59m(2)g(-1). Batch experiments showed that removal ratio increased in the order of copper (19.83%), zinc (34.35%), cadmium (59.82%), and lead (73.99%) in mixed solutions with the same initial concentration (50mgL(-1)). The results indicated that the Sips isotherm model was the most suitable for describing the experimental data of lead and copper. The maximum adsorption capacity of lead and copper determined to Sips model were 491mgg(-1) and 247mgg(-1). The obtained pore diffusion coefficients for lead and copper were found to be 1.02×10(-6) and 2.42×10(-7)m(2)s(-1), respectively. Post-sorption characteristics indicated that surface precipitation was the primary mechanism of lead and copper removal by the carbon foam, while the functional groups on the surface of the foam did not affect metal adsorption. PMID:25819762

  15. Carbon nanohybrids used as catalysts and emulsifiers for reactions in biphasic aqueous/organic systems

    Institute of Scientific and Technical Information of China (English)

    Daniel E. Resasco

    2014-01-01

    This mini-review summarizes some novel aspects of reactions conducted in aqueous/organic emul-sions stabilized by carbon nanohybrids functionalized with catalytic species. Carbon nanohybrids represent a family of solid catalysts that not only can stabilize water-oil emulsions in the same fash-ion as Pickering emulsions, but also catalyze reactions at the liquid/liquid interface. Several exam-ples are discussed in this mini-review. They include (a) aldol condensation-hydrodeoxygenation tandem reactions catalyzed by basic (MgO) and metal (Pd) catalysts, respectively; (b) Fischer-Tropsch synthesis catalyzed by carbon-nanotube-supported Ru;and (c) emulsion polymerization of styrene for the production of conductive polymer composites. Conducting these reactions in emul-sion generates important advantages, such as increased liquid/liquid interfacial area that conse-quently means faster mass transfer rates of molecules between the two phases, effective separation of products from the reaction mixture by differences in the water-oil solubility, and significant changes in product selectivity that can be adjusted by modifying the emulsion characteristics.

  16. Carbon nanotubes dispersed in aqueous solution by ruthenium(ii) polypyridyl complexes.

    Science.gov (United States)

    Huang, Kewei; Saha, Avishek; Dirian, Konstantin; Jiang, Chengmin; Chu, Pin-Lei E; Tour, James M; Guldi, Dirk M; Martí, Angel A

    2016-07-21

    Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs. These studies show that the photoluminescence of both, that is, of the ruthenium complexes and of SWCNTs, are quenched when they interact with each other. Pump-probe transient absorption experiments were performed to shed light onto the nature of the photoluminescence quenching, showing carbon nanotube-based bands with picosecond lifetimes, but no new bands which could be unambigously assigned to photoinduced charge transfer process. Thus, from the spectroscopic data, we conclude that quenching of the photoluminescence of the ruthenium complexes is due to energy transfer to proximal SWCNTs. PMID:27353007

  17. Optimizing the electrochemical performance of aqueous symmetric supercapacitors based on an activated carbon xerogel

    Science.gov (United States)

    Calvo, E. G.; Lufrano, F.; Staiti, P.; Brigandì, A.; Arenillas, A.; Menéndez, J. A.

    2013-11-01

    A highly porous carbon xerogel was synthesized by means of physical activation. The activated carbon xerogel, which displayed a well-developed porous texture (micro- and meso-porosity), was employed as electrode material in different supercapacitors. In assessing the performance of the supercapacitors, special attention was paid to their dimensions and the type of electrolyte used. Both the method of electrode manufacture (rolling and punching of 1 cm2 pellets vs. casting by means of a film applicator to produce 4 cm2 electrodes) and the type of supercapacitor (Swagelok (R) system vs. cell with graphite plate current collectors) were evaluated. The results reveal that the cells with larger electrodes were able to store higher amounts of energy. In addition to the cells, the electrochemical characteristics in aqueous electrolytes with a different pH were studied (H2SO4, Na2SO4 and KOH, 1 M). The highest capacitance values were achieved with sulphuric acid (196 F g-1 as opposed to 140 and 106 F g-1 for Na2SO4 and KOH, respectively), probably due to its higher ionic conductivity and the basic nature of the oxygen functionalities found on the surface of the carbon xerogel. Nevertheless, because of the corrosive character of sulphuric acid, Na2SO4 would be a more suitable electrolyte.

  18. Sorption of lanthanum and erbium from aqueous solution by activated carbon prepared from rice husk

    International Nuclear Information System (INIS)

    A biomass agricultural waste material, rice husk (RH) was used for preparation of activated carbon by chemical activation using phosphoric acid. The effect of various factors, e.g. time, ph, initial concentration and temperature of carbon on the adsorption capacity of lanthanum and erbium were quantitatively determined. It was found that the monolayer capacity is 175.4 mg/g for La(III) and 250 mg/g for Er(III) . The calculated activation energy of La(III) adsorption on the activated carbon derived from rice husk was equal to 5.84 kJ/ mol while 14.6 kJ/ mol for Er(III), which confirm that the reaction is mainly particle-diffusion controlled. The kinetics of sorption was described by a model of a pseudo-second-order. External diffusion and intra-particular diffusion were examined. The experimental data show that the external diffusion and intra-particular diffusion are significant in the determination of the sorption rate. Therefore, the developed sorbent is considered as a better replacement technology for removal of La (III) and Er(III) ions from aqueous solution due to its low cost and good efficiency, fast kinetics, as well as easy to handle and thus no or small amount of secondary sludge is obtained in this application

  19. Mineral elements of subtropical tree seedlings in response to elevated carbon dioxide and nitrogen addition.

    Directory of Open Access Journals (Sweden)

    Wenjuan Huang

    Full Text Available Mineral elements in plants have been strongly affected by increased atmospheric carbon dioxide (CO2 concentrations and nitrogen (N deposition due to human activities. However, such understanding is largely limited to N and phosphorus in grassland. Using open-top chambers, we examined the concentrations of potassium (K, calcium (Ca, magnesium (Mg, aluminum (Al, copper (Cu and manganese (Mn in the leaves and roots of the seedlings of five subtropical tree species in response to elevated CO2 (ca. 700 μmol CO2 mol(-1 and N addition (100 kg N ha(-1 yr(-1 from 2005 to 2009. These mineral elements in the roots responded more strongly to elevated CO2 and N addition than those in the leaves. Elevated CO2 did not consistently decrease the concentrations of plant mineral elements, with increases in K, Al, Cu and Mn in some tree species. N addition decreased K and had no influence on Cu in the five tree species. Given the shifts in plant mineral elements, Schima superba and Castanopsis hystrix were less responsive to elevated CO2 and N addition alone, respectively. Our results indicate that plant stoichiometry would be altered by increasing CO2 and N deposition, and K would likely become a limiting nutrient under increasing N deposition in subtropics.

  20. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    Science.gov (United States)

    Yu, Fei; Ma, Jie; Han, Sheng

    2014-06-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kinetics of TC onto CNTs-3.2%O might be dependent on both intra-particle diffusion and boundary layer diffusion. The maximum adsorption capacity of TC on CNTs-3.2%O was achieved in the pH range of 3.3-8.0 due to formation of water clusters or H-bonds. Furthermore, the presence of Cu2+ could significantly enhanced TC adsorption at pH of 5.0. However, the solution ionic strength did not exhibit remarkable effect on TC adsorption. In addition, when pH is beyond the range (3.3-8.0), the electrostatic interactions caused the decrease of TC adsorption capacity. Our results indicate that surface properties and aqueous solution chemistry play important roles in TC adsorption on MWCNTs.

  1. Interaction of fragmented double-stranded DNA with carbon nanotubes in aqueous solution

    Science.gov (United States)

    Gladchenko, G. O.; Karachevtsev, M. V.; Leontiev, V. S.; Valeev, V. A.; Glamazda, A. Yu.; Plokhotnichenko, A. M.; Stepanian, S. G.

    Aqueous suspensions of ultrasonically fragmented double-stranded (fds-) DNA and single-walled carbon nanotubes (SWNTs) have been investigated by UV- and IR-absorption, NIR-emission and Raman spectroscopy. According to gel-electrophoresis, the lengths of the polymer fragments were 100-500 base pairs. Analysis of IR and UV data indicates the presence of both double-stranded (ds) and single-stranded (ss)-regions in the fragments. SWNT complex with DNA was revealed by NIR-emission and Raman spectroscopy. It turned out that fds-DNA is less efficient in holding nanotubes in the aqueous solution than ss-DNA. From the UV-data, the character of the helix-coil transition is seen to be like that for fds-DNA off and on nanotube, however, DNA thermostability increased in this latter case. The effective charge density on the DNA sugar-phosphate backbone of the fds-DNA:SWNT hybrid was less than that of DNA alone. Spectroscopic data can be explained by a model in which the formation of hybrids starts due to the interaction between untwisted ss-regions of DNA and the nanotube: the strands wrap on the tube and thus create an 'anchor' for the whole polymer. The ds-part of the polymer is located close to the nanotube.

  2. Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors

    Science.gov (United States)

    Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

    2014-11-01

    In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

  3. Studies on removal of NH4+-N from aqueous solution by using the activated carbons derived from rice husk

    International Nuclear Information System (INIS)

    Water pollution caused by ammonia nitrogen has attracted a great attention as its toxicity affects both the environment and human health. The objective of this paper was to investigate the adsorption behavior of NH4+-N from aqueous solution by activated carbons prepared from rice husk. The physico-chemical properties of the activated carbon were characterized by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that the NH4+-N adsorption on the rice husk derived carbons was dependent on adsorbent dosage and solution pH. The adsorption kinetics and isotherms of NH4+-N by rice husk carbon were also investigated, and good correlation coefficients were obtained for the pseudo-second order kinetic equation. Dubinin-Radushkevitch (D-R) adsorption isotherm model could better describe the adsorption behavior of NH4+-N on the rice husk carbon. Calculated by D-R model, the adsorption course of NH4+-N on the rice husk carbon was favored chemical ion-exchange mechanism. Moreover, the activated carbon adsorbed NH4+-N was highly fertilizer conservation especially for the nitrogen element. It was proposed that the amount of removed NH4+-N from aqueous solutions would increase evidently treated by rice husk carbon if combined with biological method. -- Highlights: ► The dosage of rice husk carbon and pH affected the removal of NH4+-N from aqueous solution. ► D-R model could better describe the adsorption behavior of NH4+-N on the rice husk carbon. ► The removing of NH4+-N would be risen by rice husk carbon if combined with biological method.

  4. Surface activated carbon nanospheres for fast adsorption of silver ions from aqueous solutions.

    Science.gov (United States)

    Song, Xianghua; Gunawan, Poernomo; Jiang, Rongrong; Leong, Susanna Su Jan; Wang, Kean; Xu, Rong

    2011-10-30

    We report the synthesis and activation of colloidal carbon nanospheres (CNS) for adsorption of Ag(I) ions from aqueous solutions. CNS (400-500 nm in diameter) was synthesized via simple hydrothermal treatment of glucose solution. The surface of nonporous CNS after being activated by NaOH was enriched with -OH and -COO(-) functional groups. Despite the low surface area (nanoparticles on the external surface of CNS. The kinetic data can be well fitted to the pseudo-second-order kinetics model. The adsorbed silver can be easily recovered by dilute acid solutions and the CNS can be reactivated by the same treatment with NaOH solution. The excellent adsorption performance and reusability have also been demonstrated in a continuous mode. The NaOH activated CNS reported here could represent a new type of low-cost and efficient adsorbent nanomaterials for removal of trace Ag(I) ions for drinking water production. PMID:21862215

  5. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    International Nuclear Information System (INIS)

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 3130K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 2980K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory

  6. Removal of uranium from drinking water and other aqueous systems using modified powdered activated carbon

    International Nuclear Information System (INIS)

    A simple, rapid and eco friendly method for removal of high concentration of Uranium (U) from ground water (>2500 ppb), Mine water(>1000 ppb) and other aqueous systems has been developed based on laboratory trials using 10 litres of mine water and ground water. The removal of uranium was greater than 95% with a contact time of 10 minutes with modified powdered activated carbon (MPAC) at the natural pH of water. The concentration of Uranium left behind in drinking water after MPAC treatment (if necessary twice) was less than 15 ppb and is below WHO/AERB permissible limits. The methodology is so simple that it could be applied at remote villages to produce uranium free drinking water at the natural pH of water

  7. Electrochemical Reduction of Carbon Monoxide in Aqueous Electrolytes at Gas Diffusion Hydrophobic Electrodes

    International Nuclear Information System (INIS)

    This paper investigates the influence of the material of the electro-catalyst, the electrode composition, the type and concentration of the electrolyte, the temperature and the potential of the electrode on the electroreduction of carbon monoxide in aqueous electrolytes. The following metal powders were used as electrocatalysts: Co, Ni, Fe, Nb, Pt, W, Cu, Cd, Pb, Zn, and Raney nickel. A large series of tests showed that no organic products were synthesized in the electroysis in the presence of CO on the metals Pt, Nb, Cd, W, Cu, Pb, and Zn. The only product in the whole potential range was hydrogen, derived from the decomposition of the electrolyte. Methane, ethane, and traces of ethylene were obtained on Ni, Co, Fe, and Raney nickel. With respect to the other hydrocarbons the methane content was equal to 95%. Best results were obtained on nickel electrodes

  8. ADSORPTION OF COPPER FROM AQUEOUS SOLUTION BY ELAIS GUINEENSIS KERNEL ACTIVATED CARBON

    Directory of Open Access Journals (Sweden)

    NAJUA DELAILA TUMIN

    2008-08-01

    Full Text Available In this study, a series of batch laboratory experiments were conducted in order to investigate the feasibility of Elais Guineensis kernel or known as palm kernel shell (PKS-based activated carbon for the removal of copper from aqueous solution by the adsorption process. Investigation was carried out by studying the influence of initial solution pH, adsorbent dosage and initial concentration of copper. The particle size of PKS used was categorized as PKS–M. All batch experiments were carried out at a constant temperature of 30°C (±2°C using mechanical shaker that operated at 100 rpm. The single component equilibrium data was analyzed using Langmuir, Freundlich, Redlich-Peterson, Temkin and Toth adsorption isotherms.

  9. Adsorption of a textile dye from aqueous solutions by carbon nanotubes

    International Nuclear Information System (INIS)

    Multi-walled and single-walled carbon nanotubes were used as adsorbents for the removal of Reactive Blue 4 textile dye from aqueous solutions. The adsorbents were characterised using Raman spectroscopy, N2 adsorption/desorption isotherms and scanning and transmission electron microscopy. The effects of pH, agitation time and temperature on adsorption capacity were studied. In the acidic pH region, the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 4 hours for both adsorbents. For Reactive Blue 4 dye, Liu isotherm model gave the best fit for the equilibrium data. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 502.5 and 567.7 mg g-1 for MWCNT and SWCNT, respectively. (author)

  10. Kinetic adsorption of application of carbon nanotubes for Pb(II) removal from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    Nassereldeen A Kabbashi; Muataz A Atieh; Abdullah Al-Mamun; Mohamed E S Mirghami; MD Z Alam; Noorahayu Yahya

    2009-01-01

    The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(II) was reach to maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of Pb(II) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). From this study, the results indicates that the highest percentage removal of Pb (96.03%) can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min.

  11. The accuracy and limitations of a new meter used to measure aqueous carbon dioxide

    DEFF Research Database (Denmark)

    Moran, Damian; Tirsgård, Bjørn; Steffensen, John F.

    2010-01-01

    The OxyGuard CO2 Analyzer is a novel meter that can directly measure aqueous CO2 gas pressure using a water-resistant gas-permeable membrane and infra-red absorption cell. The pCO2 is converted to a concentration via a solubility factor determined from the calibration procedure and a thermistor. We...... undertook to independently validate the precision and utility of this meter. Water flow over the probe membrane was a key determinant of the reaction time. At water velocities of ≥30 cm s−1 the time to 99% span was 6–7 min, while at 0 cm s−1 it was 55–60 min. Temperature and CO2(aq) concentration did...... where accurate pH and carbonate alkalinity determinations are difficult to obtain, such as saline waters and waters of high organic loadings....

  12. Carbon dioxide assist for non-aqueous sodium–oxygen batteries

    KAUST Repository

    Das, Shyamal K.

    2013-02-01

    We report a novel non-aqueous Na-air battery that utilizes a gas mixture of CO2 and O2. The battery exhibits a high specific energy of 6500-7000 Whkg- 1 (based on the carbon mass) over a range of CO2 feed compositions. The energy density achieved is higher, by 200% to 300%, than that obtained in pure oxygen. Ex-situ FTIR and XRD analysis reveal that Na2O2, Na2C2O 4 and Na2CO3 are the principal discharge products. The Na-CO2/O2 and Mg-CO2/O 2 battery platforms provide a promising, new approach for CO 2 capture and generation of electrical energy. © 2012 Elsevier B.V. All rights reserved.

  13. Molecular dynamics investigation of carbon nanotube junctions in non-aqueous solutions

    KAUST Repository

    Gkionis, Konstantinos

    2014-07-23

    The properties of liquids in a confined environment are known to differ from those in the bulk. Extending this knowledge to geometries defined by two metallic layers in contact with the ends of a carbon nanotube is important for describing a large class of nanodevices that operate in non-aqueous environments. Here we report a series of classical molecular dynamics simulations for gold-electrode junctions in acetone, cyclohexane and N,N-dimethylformamide solutions and analyze the structure and the dynamics of the solvents in different regions of the nanojunction. The presence of the nanotube has little effect on the ordering of the solvents along its axis, while in the transversal direction deviations are observed. Importantly, the orientational dynamics of the solvents at the electrode-nanotube interface differ dramatically from that found when only the electrodes are present.

  14. A Layout for the Carbon Capture with Aqueous Ammonia without Salt Precipitation

    DEFF Research Database (Denmark)

    Bonalumi, Davide; Valenti, Gianluca; Lillia, Stefano;

    2016-01-01

    Post-combustion carbon capture technologies seem to be necessary to realize the CO2 mitigation policies internationally shared for the next future, despite none of them appears to be ready for full-scale applications. This work considers the aqueous ammonia based process for a coal-fired Ultra...... Super Critical power plant. Two layouts are simulated with Aspen Plus employing the recently recalibrated Extended UNIQUAC thermodynamic model. The first one operates at chilling conditions, which yield to salt precipitation, and is taken as reference because already analyzed in previous studies......, a lower SPECCA of 2.58 MJ/kgco2. The latter layout is a better choice also from the perspective of the plant operation since it does not present the salt precipitation....

  15. Adsorptive removal of congo red dye from aqueous solution using bael shell carbon

    International Nuclear Information System (INIS)

    This study investigates the potential use of bael shell carbon (BSC) as an adsorbent for the removal of congo red (CR) dye from aqueous solution. The effect of various operational parameters such as contact time, temperature, pH, and dye concentration were studied. The adsorption kinetics was modeled by first-order reversible kinetics, pseudo-first-order kinetics, and pseudo-second-order kinetics. The dye uptake process obeyed the pseudo-second-order kinetic expression at pH 5.7, 7 and 8 whereas the pseudo-first-order kinetic model was fitted well at pH 9. Langmuir, Freundlich and Temkin adsorption models were applied to fit adsorption equilibrium data. The best-fitted data was obtained with the Freundlich model. Thermodynamic study showed that adsorption of CR onto BSC was endothermic in nature and favorable with the positive ΔHo value of 13.613 kJ/mol.

  16. Removal of dyes from aqueous solutions using activated carbon prepared from rice husk residue.

    Science.gov (United States)

    Li, Yaxin; Zhang, Xian; Yang, Ruiguang; Li, Guiying; Hu, Changwei

    2016-01-01

    The treatment of dye wastewater by activated carbon (AC) prepared from rice husk residue wastes was studied. Batch adsorption studies were conducted to investigate the effects of contact time, initial concentration (50-450 mg/L), pH (3-11) and temperature (30-70 °C) on the removal of methylene blue (MB), neutral red, and methyl orange. Kinetic investigation revealed that the adsorption of dyes followed pseudo-second-order kinetics. The results suggested that AC was effective to remove dyes, especially MB, from aqueous solutions. Desorption studies found that chemisorption by the adsorbent might be the major mode of dye removal. Fourier transform infrared results suggested that dye molecules were likely to combine with the O-H and P=OOH groups of AC. PMID:26942535

  17. Adsorption of a textile dye from aqueous solutions by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Fernando M.; Bergmann, Carlos P., E-mail: fernando.machado@hotmail.com.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Dept. de Materiais; Lima, Eder C.; Adebayo, Matthew A. [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Inst. de Quimica; Fagan, Solange B. [Centro Universitario Franciscano (UNIFRA), Santa Maria, RS (Brazil). Area de Ciencias Tecnologicas

    2014-08-15

    Multi-walled and single-walled carbon nanotubes were used as adsorbents for the removal of Reactive Blue 4 textile dye from aqueous solutions. The adsorbents were characterised using Raman spectroscopy, N{sub 2} adsorption/desorption isotherms and scanning and transmission electron microscopy. The effects of pH, agitation time and temperature on adsorption capacity were studied. In the acidic pH region, the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 4 hours for both adsorbents. For Reactive Blue 4 dye, Liu isotherm model gave the best fit for the equilibrium data. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 502.5 and 567.7 mg g{sup -1} for MWCNT and SWCNT, respectively. (author)

  18. Application of adsorption process by activated carbon derived from scrap tires for Pb+2 removal from aqueous solutions

    OpenAIRE

    Edris Hoseinzadeh; Ali Reza Rahmani; Ghorban Asgari; Mohamad Taghi Samadi; Ghodratollah Roshanaei; Mohammad Reza Zare

    2013-01-01

    Background and Aim: Heavy metals have been recognized as very poisonous elements and their discharge into water sources can cause damaging effects on human and environmental health. The present study aimed at producing activated carbon from scrap tires and using it in removing Pb+2 from synthetic aqueous solutions. Materials and Methods: In this experimental study, activated carbon powder was derived from scrap tires under laboratory conditions. The effect of Pb (II) ions wi...

  19. Preparation and Utilization of Kapok Hull Carbon for the Removal of Rhodamine-B from Aqueous Solution

    OpenAIRE

    P. S. Syed Shabudeen; R. Venckatesh; S. Pattabhi

    2006-01-01

    A carbonaceous sorbent prepared from the indegeneous agricultural waste (which is facing solid waste disposal problem) Kapok Hull, by acid treatment was tested for its efficiency in removing basic dyes. Batch kinetic and isotherm experiments were conducted to determine the sorption and desorption of the Rhodamine-B from aqueous solution with activated carbon. The factors affecting the rate processes involved in the removal of dye for initial dye concentration, agitation time, and carbon dose ...

  20. Carbonate Mineral Formation under the Influence of Limestone-Colonizing Actinobacteria: Morphology and Polymorphism

    Science.gov (United States)

    Cao, Chengliang; Jiang, Jihong; Sun, Henry; Huang, Ying; Tao, Faxiang; Lian, Bin

    2016-01-01

    Microorganisms and their biomineralization processes are widespread in almost every environment on earth. In this work, Streptomyces luteogriseus DHS C014, a dominant lithophilous actinobacteria isolated from microbial mats on limestone rocks, was used to investigate its potential biomineralization to allow a better understanding of bacterial contributions to carbonate mineralization in nature. The ammonium carbonate free-drift method was used with mycelium pellets, culture supernatant, and spent culture of the strain. Mineralogical analyses showed that hexagonal prism calcite was only observed in the sub-surfaces of the mycelium pellets, which is a novel morphology mediated by microbes. Hemispheroidal vaterite appeared in the presence of spent culture, mainly because of the effects of soluble microbial products (SMP) during mineralization. When using the culture supernatant, doughnut-like vaterite was favored by actinobacterial mycelia, which has not yet been captured in previous studies. Our analyses suggested that the effects of mycelium pellets as a molecular template almost gained an advantage over SMP both in crystal nucleation and growth, having nothing to do with biological activity. It is thereby convinced that lithophilous actinobacteria, S. luteogriseus DHS C014, owing to its advantageous genetic metabolism and filamentous structure, showed good biomineralization abilities, maybe it would have geoactive potential for biogenic carbonate in local microenvironments.

  1. Carbon sources supporting benthic mineralization in mangrove and adjacent seagrass sediments (Gazi Bay, Kenya

    Directory of Open Access Journals (Sweden)

    S. Bouillon

    2004-01-01

    Full Text Available The origin of carbon substrates used by in situ sedimentary bacterial communities was investigated in an intertidal mangrove ecosystem and in adjacent seagrass beds in Gazi bay (Kenya by δ13C analysis of bacteria-specific PLFA (phospholipid fatty acids and bulk organic carbon. Export of mangrove-derived organic matter to the adjacent seagrass-covered bay was evident from sedimentary total organic carbon (TOC and δ13CTOC data. PLFA δ13C data indicate that the substrate used by bacterial communities varied strongly and that exported mangrove carbon was a significant source for bacteria in the adjacent seagrass beds. Within the intertidal mangrove forest, bacterial PLFA at the surface layer (0-1cm typically showed more enriched δ13C values than deeper (up to 10cm sediment layers, suggesting a contribution from microphytobenthos and/or inwelled seagrass material. Under the simplifying assumption that seagrasses and mangroves are the dominant potential end-members, the estimated contribution of mangrove-derived carbon to benthic mineralization in the seagrass beds (16-74% corresponds fairly well to the estimated contribution of mangrove C to the sedimentary organic matter pool (21-71% across different seagrass sites. Based on the results of this study and a compilation of literature data, we suggest that trapping of allochtonous C is a common feature in seagrass beds and often represents a significant source of C for sediment bacteria - both in cases where seagrass C dominates the sediment TOC pool and in cases where external inputs are significant. Hence, it is likely that data on community respiration rates systematically overestimate the role of in situ mineralization as a fate of seagrass production.

  2. Sclerostin regulates release of bone mineral by osteocytes by induction of carbonic anhydrase 2.

    Science.gov (United States)

    Kogawa, Masakazu; Wijenayaka, Asiri R; Ormsby, Renee T; Thomas, Gethin P; Anderson, Paul H; Bonewald, Lynda F; Findlay, David M; Atkins, Gerald J

    2013-12-01

    The osteocyte product sclerostin is emerging as an important paracrine regulator of bone mass. It has recently been shown that osteocyte production of receptor activator of NF-κB ligand (RANKL) is important in osteoclastic bone resorption, and we reported that exogenous treatment of osteocytes with sclerostin can increase RANKL-mediated osteoclast activity. There is good evidence that osteocytes can themselves liberate mineral from bone in a process known as osteocytic osteolysis. In the current study, we investigated sclerostin-stimulated mineral dissolution by human primary osteocyte-like cells (hOCy) and mouse MLO-Y4 cells. We found that sclerostin upregulated osteocyte expression of carbonic anhydrase 2 (CA2/Car2), cathepsin K (CTSK/Ctsk), and tartrate-resistant acid phosphatase (ACP5/Acp5). Because acidification of the extracellular matrix is a critical step in the release of mineral from bone, we further examined the regulation by sclerostin of CA2. Sclerostin stimulated CA2 mRNA and protein expression in hOCy and in MLO-Y4 cells. Sclerostin induced a decrease in intracellular pH (pHi) in both cell types as well as a decrease in extracellular pH (pHo) and the release of calcium ions from mineralized substrate. These effects were reversed in the co-presence of the carbonic anhydrase inhibitor, acetozolamide. Car2-siRNA knockdown in MLO-Y4 cells significantly inhibited the ability of sclerostin to both reduce the pHo and release calcium from a mineralized substrate. Knockdown in MLO-Y4 cells of each of the putative sclerostin receptors, Lrp4, Lrp5 and Lrp6, using siRNA, inhibited the sclerostin induction of Car2, Catk and Acp5 mRNA, as well as pHo and calcium release. Consistent with this activity of sclerostin resulting in osteocytic osteolysis, human trabecular bone samples treated ex vivo with recombinant human sclerostin for 7 days exhibited an increased osteocyte lacunar area, an effect that was reversed by the co-addition of acetozolamide. These findings

  3. Microstructural and geo environmental influence of carbonate minerals on the heavy attenuation of Kaolinite

    International Nuclear Information System (INIS)

    The sorption characteristics of soils, which are fundamental to contaminant attenuation, depend on many soil-related and contaminant-related factors. The carbonate-rich soils in semi-arid regions provide the motivation for this study on the role of carbonates on contaminant attenuation. Previous reported studies have shown that carbonates exert considerable influence on the retention of heavy metals in soils. This study investigates kaolinite-calcite-contaminant interaction at different p H values and heavy metals concentrations. Particular attention is paid to the resultant effect on contaminant attenuation. To achieve the stated objectives, several batch equilibrium and XRD analyses were performed. p H control experiments were conducted to evaluate the influence of calcite content on sorption of Zn in the kaolinite-calcite mixtures. The interaction process of the clay fraction and carbonate was monitored through XRD analyses of the soil samples at various stages of the tests. It is concluded that the presence of carbonate minerals in clayey soils causes an increase in heavy metal attenuation of kaolinite

  4. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    Science.gov (United States)

    Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition

  5. Soil carbon and nitrogen mineralization under different tillage systems and Permanent Groundcover cultivation between Orange trees

    Directory of Open Access Journals (Sweden)

    Elcio Liborio Balota

    2011-06-01

    Full Text Available The objective of this work was to evaluate the alterations in carbon and nitrogen mineralization due to different soil tillage systems and groundcover species for intercropped orange trees. The experiment was established in an Ultisol soil (Typic Paleudults originated from Caiuá sandstone in northwestern of the state of Paraná, Brazil, in an area previously cultivated with pasture (Brachiaria humidicola. Two soil tillage systems were evaluated: conventional tillage (CT in the entire area and strip tillage (ST with a 2-m width, each with different groundcover vegetation management systems. The citrus cultivar utilized was the 'Pera' orange (Citrus sinensis grafted onto a 'Rangpur' lime rootstock. The soil samples were collected at a 0-15-cm depth after five years of experiment development. Samples were collected from under the tree canopy and from the inter-row space after the following treatments: (1 CT and annual cover crop with the leguminous Calopogonium mucunoides; (2 CT and perennial cover crop with the leguminous peanut Arachis pintoi; (3 CT and evergreen cover crop with Bahiagrass Paspalum notatum; (4 CT and cover crop with spontaneous B. humidicola grass vegetation; and (5 ST and maintenance of the remaining grass (pasture of B. humidicola. The soil tillage systems and different groundcover vegetation influenced the C and N mineralization, both under the tree canopy and in the inter-row space. The cultivation of B. humidicola under strip tillage provided higher potential mineralization than the other treatments in the inter-row space. Strip tillage increased the C and N mineralization compared to conventional tillage. The grass cultivation increased the C and N mineralization when compared to the others treatments cultivated in the inter-row space.

  6. Design of the passive personal dosimeter for miners using an allyl diglycol carbonate plastic. Phase 1

    International Nuclear Information System (INIS)

    The report summarizes the results of the feasibility study on the design and development of a passive personal dosimeter incorporating an allyl diglycol carbonate plastic (CR39) detector, for use by uranium miners. Based upon the feasibility study, a passive personal dosimeter using a capacitor-type electrostatic enhancement device has been designed. Preliminary tests indicate that the prototype could be used in the mine environment to differentiate radon and thoron daughters with a detection efficiency comparable to that of a typical active device. Further study is required, however, into the possible influence in the mine environment of local variations in charged fraction, upon the calibration of this dosimeter

  7. Topsoil organic carbon mineralization and CO2 evolution of three paddy soils from South China and the temperature dependence

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-hui; LI Lian-qing; PAN Gen-xing

    2007-01-01

    Carbon mineralization and its response to climatic warming have been receiving global attention for the last decade.Although the virtual influence of temperature effect is still in great debate,little is known on the mineralization of organic carbon(SOC) of paddy soils of China under warming.SOC mineralization of three major types of China's paddy soils is studied through laboratory incubation for 114 d under soil moisture regime of 70% water holding capacity at 20℃ and 25℃ respectively.The carbon that mineralized as CO2 evolved was measured every day in the first 32 d and every two days in the following days.Carbon mineralized during the 114 d incubation ranged from 3.51 to 9.22 mg CO2-C/gC at 20℃ and from 4.24 to 11.35 mg CO2-C/gC at 25℃ respectively;and a mineralizable C pool in the range of 0.24 to 0.59 gC/kg.varying with difierent soils.The whole course of C mineralization in the 114 d incubation could be divided into three stages of varying rates,representing the three subpools of the total mineralizable C:very actively mineralized C at 1-23 d,actively mineralized C at 24-74 d and a slowly mineralized pool with low and more or 1ess stabilized C mineralization rate at 75-114 d.The calculated Ω10 values ranged from 1.0 to 2.4,varying with the soil types and N status.Neither the total SOC pool nor the labile C pool could account for the total mineralization potential of the soils studied,despite a well correlation of labile C with the shortly and actively mineralized C,which were shown in sensitive response to soil wanning.However,the portion of microbial C pool and the soil C/N ratio controlled the C mineralization and the temperature dependence,Therefore,C sequestration may not result in an increase of C mineralization proportionally.The relative control of C bioavailability and microbial metabolic activity on C mineralization with respect to stabilization of sequestered C in the paddy soils of China is to be further studied.

  8. Removals of aqueous sulfur dioxide and hydrogen sulfide using CeO2-NiAl-LDHs coating activated carbon and its mix with carbon nano-tubes

    KAUST Repository

    Li, Jing

    2015-07-01

    Ce-doped NiAl/layered double hydroxide was coated at activated carbon by urea hydrolysis method (CeO2-NiAl-LDHs/AC) in one pot, which was characterized by X-ray diffraction, infrared spectra, field emission scanning electron microscope and electrochemical techniques. CeO2-NiAl-LDHs/AC shows good uptake for aqueous sulfur dioxide (483.09mg/g) and hydrogen sulfide (181.15mg/g), respectively at 25°C. Meanwhile, the electrochemical removals of aqueous sulfur dioxide and hydrogen sulfide were respectively investigated at the mix of CeO2-NiAl-LDHs/AC and carbon nano-tubes modified homed paraffin-impregnated electrode. Both sulfur dioxide and hydrogen sulfide could be effectively oxidized to sulfuric acid at 1.0V in alkaline aqueous solution. © 2015 Elsevier B.V.

  9. Sorption study of uranium on carbon spheres hydrothermal synthesized with glucose from aqueous solution

    International Nuclear Information System (INIS)

    The ability of oxygen-rich carbon spheres (CSs) produced by hydrothermal carbonization with the glucose has been explored for the removal and recovery of uranium from aqueous solutions. The micro-morphology and structure of CSs were characterized by FT-IR and SEM. The influences of different experimental parameters such as solution pH, initial concentration, contact time, ionic strength and temperature on adsorption were investigated. The CSs showed the highest uranium sorption capacity at initial pH of 6.0 and contact time of 25 min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir isotherm. The thermodynamic parameters, ΔGdeg(298 K), ΔHdeg and ΔSdeg were determined to be -16.88, 12.09 kJ mol-1 and 197.87 J mol-1 K-1, respectively, which demonstrated the sorption process of CSs towards U(VI) was feasible, spontaneous and endothermic in nature. The adsorbed CSs could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 3.0 g CSs. (author)

  10. Sodium phthalamates as corrosion inhibitors for carbon steel in aqueous hydrochloric acid solution

    International Nuclear Information System (INIS)

    Highlights: → N-Alkyl-sodium phthalamates as corrosion inhibitors for industry in acidic medium. → Compounds behaved as mixed type inhibitors and followed Langmuir adsorption isotherm. → Efficiencies were proportional to aliphatic chain length and inhibitor concentration. → Iron complexes and chelates with phthalamates contributed to carbon steel protection. - Abstract: Three compounds of N-alkyl-sodium phthalamates were synthesized and tested as corrosion inhibitors for carbon steel in 0.5 M aqueous hydrochloric acid. Tests showed that inhibitor efficiencies were related to aliphatic chain length and dependent on concentration. N-1-n-tetradecyl-sodium phthalamate displayed moderate efficiency against uniform corrosion, 42-86% at 25 deg. C and 25-60% at 40 oC. Tests indicated that compounds behave as mixed type inhibitors where molecular adsorption on steel followed Langmuir isotherm, whereas thermodynamic suggested that a physisorption process occurred. XPS analysis confirmed film formation on surface, where Fe+2 complexes and Fe+2 chelates with phthalamates prevented steel from further corrosion.

  11. Ciprofloxacin adsorption from aqueous solution onto chemically prepared carbon from date palm leaflets

    Institute of Scientific and Technical Information of China (English)

    El-Said Ibrahim El-Shafey; Haider Al-Lawati; Asmaa Soliman Al-Sumri

    2012-01-01

    A chemically prepared carbon was synthesized from date palm leaflets via sulphuric acid carbonization at 160℃.Adsorption of ciprofloxacin (CIP) from aqueous solution was investigated in terms of time,pH,concentration,temperature and adsorbent status (wet and dry).The equilibrium time was found to be 48 hr.The adsorption rate was enhanced by raising the temperature for both adsorbents,with adsorption data fitting a pseudo second-order model well.The activation energy,Ea,was found to be 17 kJ/mol,indicating a diffusion-controlled,physical adsorption process.The maximum adsorption was found at initial pH 6.The wet adsorbent showed faster removal with higher uptake than the dry adsorbent,with increased performance as temperature increased (25-45℃ ).The equilibrium data were found to fit the Langmuir model better than the Freundlich model.The thermodynamic parameters showed that the adsorption process is spontaneous and endothermic.The adsorption mechanism is mainly related to cation exchange and hydrogen bonding.

  12. The Use of Microwave Derived Activated Carbon for Removal of Heavy Metal in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Rafeah Wahi

    2011-09-01

    Full Text Available Palm oil processing waste which is palm oil kernel shell (POKS was converted to activated carbon (POKS AC through 7 min microwave pyrolysis at temperature 270 °C followed by chemical activation using NaOH and HCl. The adsorption study on Ni(II, Cu(II and Cr(IV was conducted to evaluate the efficiency of the prepared activated carbon to remove heavy metal. The adsorption capacity was determined as a function of adsorbate initial concentration and adsorbent dosage. Based on Langmuir isotherm, Ni(II showed highest adsorption capacity of 40.98 mg/g, followed by Cr(IV and Cu(II with adsorption capacity of 40.60 mg/g and 13.69 mg/g, respectively. Cr(IV and Cu(II showed better fitting to Freundlich isotherm model with high correlation regression indicating the applicability of heterogeneous adsorption. Ni(II show better fitting with Langmuir isotherm that indicate monolayer coverage. The use of POKS AC is not only effective for adsorption of Cr(IV, Ni(II and Cu(II in aqueous solution but also helps to overcome the over abundance of POKS waste problem.

  13. Effect of aqueous electrolytes on the electrochemical behaviors of supercapacitors based on hierarchically porous carbons

    Science.gov (United States)

    Zhang, Xiaoyan; Wang, Xianyou; Jiang, Lanlan; Wu, Hao; Wu, Chun; Su, Jingcang

    2012-10-01

    Hierarchically porous carbons (HPCs) have been prepared by sol-gel self-assembly technology with nickel oxide and surfactant as the dual template. The porous carbons are further activated by nitric acid. The electrochemical behaviors of supercapacitors using HPCs as electrode material in different aqueous electrolytes, e.g., (NH4)2SO4, Na2SO4, H2SO4 and KOH are studied by cyclic voltametry, galvanostatic charge/discharge, cyclic life, leakage current, self-discharge and electrochemical impedance spectroscopy. The results demonstrate that the supercapacitors in various electrolytes perform definitely capacitive behaviors; especially in 6 M KOH electrolyte the supercapacitor represents the best electrochemical performance, the shortest relaxation time, and nearly ideal polarisability. The energy density of 8.42 Wh kg-1 and power density of 17.22 kW kg-1 are obtained at the operated voltage window of 1.0 V. Especially, the energy density of 11.54 Wh kg-1 and power density of 10.58 kW kg-1 can be achieved when the voltage is up to 1.2 V.

  14. Degradation of triclosan in aqueous solution by dielectric barrier discharge plasma combined with activated carbon fibers.

    Science.gov (United States)

    Xin, Lu; Sun, Yabing; Feng, Jingwei; Wang, Jian; He, Dong

    2016-02-01

    The degradation of triclosan (TCS) in aqueous solution by dielectric barrier discharge (DBD) plasma with activated carbon fibers (ACFs) was investigated. In this study, ACFs and DBD plasma coexisted in a planar DBD plasma reactor, which could synchronously achieve degradation of TCS, modification and in situ regeneration of ACFs, enhancing the effect of recycling of ACFs. The properties of ACFs before and after modification by DBD plasma were characterized by BET and XPS. Various processing parameters affecting the synergetic degradation of TCS were also investigated. The results exhibited excellent synergetic effects in DBD plasma-ACFs system on TCS degradation. The degradation efficiency of 120 mL TCS with initial concentration of 10 mg L(-1) could reach 93% with 1 mm thick ACFs in 18 min at input power of 80 W, compared with 85% by single DBD plasma. Meanwhile, the removal rate of total organic carbon increased from 12% at pH 6.26-24% at pH 3.50. ACFs could ameliorate the degradation efficiency for planar DBD plasma when treating TCS solution at high flow rates or at low initial concentrations. A possible degradation pathway of TCS was investigated according to the detected intermediates, which were identified by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) combined with theoretical calculation of Gaussian 09 program. PMID:26421625

  15. ADSORPTION OF Cr(VI FROM AQUEOUS SOLUTION USING CARBON-MICROSILICA COMPOSITE ADSORBENT

    Directory of Open Access Journals (Sweden)

    DEYI ZHANG

    2012-03-01

    Full Text Available In this work, Microsilica, one kind of industry solid waste material, was utilized firstly to prepare a carbon-Microsilica composite adsorbent from a partial carbonization, mixture and sulfoxidation process and was proposed for the removal of Cr(VI from solutions. The surface chemistry characteristics of the prepared adsorbent were analysis by XPS and FT-IR. The characterization results indicated that an abundant of oxygen functional groups, such as hydroxyl, carboxyl and sulfonic groups, were introduced into the surface of the prepared composite adsorbent. Meanwhile, the adsorption characteristics of Cr(VI onto the adsorbent in aqueous solutions was studied as a function of solution pH, ionic strength, contact time, and temperature. The results showed that Cr(VI adsorption onto the adsorbent is strongly dependent on pH and, to a lesser extent, ionic strength. Kinetics data were found to follow the pseudo-second-order kinetic model while the adsorption data corresponded to L-shape adsorption isotherm which corresponds to the classification of Giles. Activation thermodynamic parameters, such as activation enthalpy (ΔH*, activation entropy (ΔS*, activation Gibbs free energy (ΔG* and activation energy (E, have been evaluated and the possible adsorption mechanism also was suggested.

  16. Modelling soil organic carbon concentration of mineral soils in arable lands using legacy soil data

    DEFF Research Database (Denmark)

    Suuster, E; Ritz, Christian; Roostalu, H;

    2012-01-01

    Soil organic carbon (SOC) concentration is an essential factor in biomass production and soil functioning. SOC concentration values are often obtained by prediction but the prediction accuracy depends much on the method used. Currently, there is a lack of evidence in the soil science literature as...... map for the case study area of Tartu County where the SOC predictions ranged from 0.6 to 4.8%. Our study indicates that predictions using legacy soil maps can be used in national inventories and for up-scaling estimates of carbon concentrations from county to country scales....... to the advantages and shortcomings of the different commonly used prediction methods. Therefore, we compared and evaluated the merits of the median approach, analysis of covariance, mixed models and random forests in the context of prediction of SOC concentrations of mineral soils under arable...

  17. Normalization of stable isotope data for carbonate minerals: Implementation of IUPAC guidelines

    Science.gov (United States)

    Kim, Sang-Tae; Coplen, Tyler B.; Horita, Juske

    2015-06-01

    Carbonate minerals provide a rich source of geochemical information because their δ13C and δ18O values provide information about surface and subsurface Earth processes. However, a significant problem is that the same δ18O value is not reported for the identical carbonate sample when analyzed in different isotope laboratories in spite of the fact that the International Union of Pure and Applied Chemistry (IUPAC) has provided reporting guidelines for two decades. This issue arises because (1) the δ18O measurements are performed on CO2 evolved by reaction of carbonates with phosphoric acid, (2) the acid-liberated CO2 is isotopically fractionated (enriched in 18O) because it contains only two-thirds of the oxygen from the solid carbonate, (3) this oxygen isotopic fractionation factor is a function of mineralogy, temperature, concentration of the phosphoric acid, and δ18O value of water in the phosphoric acid, (4) researchers may use any one of an assortment of oxygen isotopic fractionation factors that have been published for various minerals at various reaction temperatures, and (5) it sometimes is not clear how one should calculate δ18OVPDB values on a scale normalized such that the δ18O value of SLAP reference water is -55.5 ‰ relative to VSMOW reference water. To enable researchers worldwide to publish the same δ18O value (within experimental uncertainty) for the same carbonate sample, we have re-evaluated reported acid fractionation factors for calcite at 25, 50, and 75 °C and propose a revised relation for the temperature dependence of oxygen isotopic acid fractionation factor, αCO2(ACID)-calcite , of where T is temperature in kelvin. At 25 °C, αCO2(ACID)-calcite = 1.01025 , the most commonly accepted value for this quantity. We propose a normalization protocol in which (1) the internationally distributed carbonate isotopic reference materials NBS 18 and NBS 19 are interspersed among carbonate samples analyzed by treatment with phosphoric acid, (2

  18. Bioreversible Derivatives of Phenol. 2. Reactivity of Carbonate Esters with Fatty Acid-like Structures Towards Hydrolysis in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Claus Larsen

    2007-10-01

    Full Text Available A series of model phenol carbonate ester prodrugs encompassing derivatives with fatty acid-like structures were synthesized and their stability as a function of pH (range 0.4 – 12.5 at 37°C in aqueous buffer solutions investigated. The hydrolysis rates in aqueous solutions differed widely, depending on the selected pro-moieties (alkyl and aryl substituents. The observed reactivity differences could be rationalized by the inductive and steric properties of the substituent groups when taking into account that the mechanism of hydrolysis may change when the type of pro-moiety is altered, e.g. n-alkyl vs. t-butyl. Hydrolysis of the phenolic carbonate ester 2-(phenoxycarbonyloxy-acetic acid was increased due to intramolecular catalysis, as compared to the derivatives synthesized from ω-hydroxy carboxylic acids with longer alkyl chains. The carbonate esters appear to be less reactive towards specific acid and base catalyzed hydrolysis than phenyl acetate. The results underline that it is unrealistic to expect that phenolic carbonate ester prodrugs can be utilized in ready to use aqueous formulations. The stability of the carbonate ester derivatives with fatty acid-like structures, expected to interact with the plasma protein human serum albumin, proved sufficient for further in vitro and in vivo evaluation of the potential of utilizing HSA binding in combination with the prodrug approach for optimization of drug pharmacokinetics.

  19. Photoassisted carbon dioxide reduction and formation of twoand three-carbon compounds. [prebiological photosynthesis

    Science.gov (United States)

    Halmann, M.; Aurian-Blajeni, B.; Bloch, S.

    1981-01-01

    The photoassisted reduction of aqueous carbon dioxide in the presence of naturally occurring minerals is investigated as a possible abiotic precursor of photosynthesis. Aqueous carbon dioxide saturated suspensions or surfaces of the minerals nontronite, bentonite, anatase, wolframite, molybdenite, minium, cinnabar and hematite were irradiated with high-pressure mercury lamps or sunlight. Chemical analyses reveal the production of formic acid, formaldehyde, methanol and methane, and the two and three-carbon compounds glyoxal (CHOCHO) and malonaldehyde (CH2(CHO)2). It is suggested that such photosynthetic reactions with visible light in the presence of semiconducting minerals may provide models for prebiological carbon and nitrogen fixation in both oxidized and reduced atmospheres.

  20. Carbon nanotubes dispersed in aqueous solution by ruthenium(ii) polypyridyl complexes

    Science.gov (United States)

    Huang, Kewei; Saha, Avishek; Dirian, Konstantin; Jiang, Chengmin; Chu, Pin-Lei E.; Tour, James M.; Guldi, Dirk M.; Martí, Angel A.

    2016-07-01

    Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs. These studies show that the photoluminescence of both, that is, of the ruthenium complexes and of SWCNTs, are quenched when they interact with each other. Pump-probe transient absorption experiments were performed to shed light onto the nature of the photoluminescence quenching, showing carbon nanotube-based bands with picosecond lifetimes, but no new bands which could be unambigously assigned to photoinduced charge transfer process. Thus, from the spectroscopic data, we conclude that quenching of the photoluminescence of the ruthenium complexes is due to energy transfer to proximal SWCNTs.Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs

  1. Changes on the nanostructure of cementitius calcium silicate hydrates (C-S-H) induced by aqueous carbonation

    OpenAIRE

    Morales-Florez, Víctor; Findling, N.; F. Brunet

    2015-01-01

    The nanostructure of the main binding phase of the hydrated cements, the calcium silicate hydrates (C-S-H), and their structural changes due to aqueous carbonation have been characterized using TEM, nitrogen physisorption, and SAXS. Synthetic C-S-H has been used for this purpose. Two different morphologies were identified, similar to the high density and low density C-S-H types. When submitting the sample to a CO 2 flux, the low density phase was completely carbonated. The carbonation by-prod...

  2. Effect of potassium salts and distillery effluent on carbon mineralization in soil.

    Science.gov (United States)

    Chandra, Suresh; Joshi, H C; Pathak, H; Jain, M C; Kalra, N

    2002-07-01

    Distillery effluent, a rich source of potassium, is used for irrigation at many places in the world. A laboratory experiment was conducted to study the influence of potassium salts present in post-methanation distillery effluent (PME) along with two other salts, KCl and K2SO4, on mineralization of carbon in soil. PME oxidized with H2O2, raw PME, KCl and K2SO4 solutions containing K equivalent to 10%, 20%, 40% and 100% of K present in PME were added to the soil separately, maintaining four replications for each treatment and control. Addition of salts up to a certain concentration stimulated C mineralization but a decline was noticed at higher concentrations. All the levels of salts caused higher CO2 evolution than the control suggesting that the presence of K salts enhanced the microbial activity resulting in increased CO2 evolution. The influence of K2SO4 was significantly higher than KCl in stimulating C mineralization in soil. Oxidized effluent had a higher stimulating effect than inorganic salts, showing the influence of other salts accompanying K in the PME. Raw PME, which contained excess organic C, increased CO2 evolution even at the highest salt level (100% PME) signifying the effect of added C on alleviating the salt stress on microbial activity. PMID:12094803

  3. Carbonate minerals in porous media decrease mobility of polyacrylic acid modified zero-valent iron nanoparticles used for groundwater remediation

    International Nuclear Information System (INIS)

    The limited transport of nanoscale zero-valent iron (nZVI) in porous media is a major obstacle to its widespread application for in situ groundwater remediation. Previous studies on nZVI transport have mainly been carried out in quartz porous media. The effect of carbonate minerals, which often predominate in aquifers, has not been evaluated to date. This study assessed the influence of the carbonate minerals in porous media on the transport of polyacrylic acid modified nZVI (PAA-nZVI). Increasing the proportion of carbonate sand in the porous media resulted in less transport of PAA-nZVI. Predicted travel distances were reduced to a few centimeters in pure carbonate sand compared to approximately 1.6 m in quartz sand. Transport modeling showed that the attachment efficiency and deposition rate coefficient increased linearly with increasing proportion of carbonate sand. -- Highlights: •Mobility of nZVI NANOFER 25S was investigated in different saturated porous media. •nZVI transport in carbonate-containing porous media was elucidated and quantified. •Mobility of polyacrylic acid-coated nZVI significantly ceases in carbonate-containing media. •Deposition rate coefficient increases linearly with increasing carbonate content. -- Carbonate minerals in porous aquifers significantly decrease the mobility of commercially available polyacrylic acid modified nanoscale zero-valent iron

  4. Differential controls on soil carbon density and mineralization among contrasting forest types in a temperate forest ecosystem

    Science.gov (United States)

    You, Ye-Ming; Wang, Juan; Sun, Xiao-Lu; Tang, Zuo-Xin; Zhou, Zhi-Yong; Sun, Osbert Jianxin

    2016-03-01

    Understanding the controls on soil carbon dynamics is crucial for modeling responses of ecosystem carbon balance to global change, yet few studies provide explicit knowledge on the direct and indirect effects of forest stands on soil carbon via microbial processes. We investigated tree species, soil, and site factors in relation to soil carbon density and mineralization in a temperate forest of central China. We found that soil microbial biomass and community structure, extracellular enzyme activities, and most of the site factors studied varied significantly across contrasting forest types, and that the associations between activities of soil extracellular enzymes and microbial community structure appeared to be weak and inconsistent across forest types, implicating complex mechanisms in the microbial regulation of soil carbon metabolism in relation to tree species. Overall, variations in soil carbon density and mineralization are predominantly accounted for by shared effects of tree species, soil, microclimate, and microbial traits rather than the individual effects of the four categories of factors. Our findings point to differential controls on soil carbon density and mineralization among contrasting forest types and highlight the challenge to incorporate microbial processes for constraining soil carbon dynamics in global carbon cycle models.

  5. Evolution of multi-mineral formation evaluation using LWD data in complex carbonates offshore Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, Paolo; Borovskaya, Irina [Schlumberger, Houston, TX (United States)

    2012-07-01

    Petrophysical Formation Evaluation using Logging While Drilling (LWD) measurements is a new requisite when drilling in carbonates reservoirs offshore Brazil. These reservoirs are difficult to characterize due to an unusual mixture of the minerals constituting the matrix and affecting rock texture. As wells are getting deeper and more expensive, an early identification of the drilled targets potential is necessary for valuable decisions. Brazil operators have been especially demanding towards service providers, pushing for development of suitable services able to positively identify and quantify not only the presence of hydrocarbons but also their flowing capability. In addition to the standard gamma ray / resistivity / porosity and density measurements, three new measurements have proven to be critical to evaluate complex carbonate formations: Nuclear Magnetic Resonance (NMR), Spectroscopy and Capture Cross-Section (sigma). Under appropriate logging conditions, NMR data provides lithology independent porosity, bound and free fluids fractions, reservoir texture and permeability. Capture Spectroscopy allows assessment of mineral composition in terms of calcite, dolomite, quartz and clay fractions, and in addition highlights presence of other heavier minerals. Finally, sigma allows performing a volumetric formation evaluation without requiring custom optimization of the classical exponents used in all forms of resistivity saturation equations. All these new measurements are inherently statistical and if provided by wireline after drilling the well they may result in significant usage of rig time. When acquired simultaneously while drilling they have three very clear advantages: 1) no extra rig time, 2) improved statistics due to long formation exposure (drilling these carbonates is a slow process and rate of penetration (ROP) rarely exceeds 10 m/hr), 3) less invasion effect and better hole condition. This paper describes the development of two LWD tools performing the

  6. Natural and artificial (90Sr radionuclides in some carbonated mineral waters used in Serbia

    Directory of Open Access Journals (Sweden)

    Janković Marija M.

    2013-01-01

    Full Text Available A radiological characterization of 7 different carbonated mineral water samples collected in the local supermarkets in the area of Belgrade (produced in Serbia was carried out. Analysis included determination of gross alpha and gross beta activities. The obtained results showed that the natural activity concentrations of alpha and beta emitting radionuclides in carbonated mineral water samples were within World Health Organization recommended levels, except for the Heba Strong and Kiseljak samples where the beta activity exceeds 1 Bq/L. For these two water samples gamma spectrometry analysis was performed as well as determination of 90Sr by oxalic method. The instrumentation used to count the gross alpha and gross beta activities, as well as for 90Sr, was a/b low level proportional counter Thermo Eberline FHT 770 T. Gamma spectrometric measurements were performed using a HPGe Canberra detector with a counting efficiency of 20%. The annual effective dose equivalent due to ingestion of investigated waters was calculated for age group >17, and obtained values are lower than 0.1 mSv recommended reference level. Finally, a comparison of the investigated waters with worldwide data was made. [Projekat Ministarstva nauke Republike Srbije, br. III43009

  7. On the role of carbonic anhydrase in the early phase of fish otolith mineralization

    Science.gov (United States)

    Beier, M.; Anken, R.

    2006-01-01

    The first step in the formation of fish otoliths, calcified structures which are responsible for the internalization of gravitational information, is based on the action of so-called Tether- (T-) cells. These T-cells appear during the very early development of the inner ear and persist only a few hours. They are characterized by a kinocilium, which is in contrast to the kinocilium of the later developing sensory hair cells not mechanosensory, but binds seeding particles containing glycogen, thereby localizing otolith formation (otolith seeding). Beating cilia distributed throughout the ear agitate seeding particles, thereby inhibiting premature agglutination. In the later development, a protein matrix is formed and mineralization/crystallization takes place. Since the enzyme carbonic anhydrase (CAH) plays a prominent role in otolith mineralization (it provides carbonate for CaCO3 precipitation), we were prompted to investigate histochemically using larval cichlid fish (Oreochromis mossambicus), whether CAH might be present as early as T-cells. Indeed, CAH was present in T-cells with prominent amounts of reaction product being located along the kinocilia and around the seeding particles. These results strongly indicate that kinocilia of T-cells act as structural guides for CAH/bicarbonate transportation towards the early otoliths’ calcification sites. Besides its role in calcification, CAH in the very early stage of otolith seeding may moreover aid in the accretion process of the precursor particles.

  8. Factors driving carbon mineralization priming effect in a soil amended with different types of biochar

    Science.gov (United States)

    Cely, P.; Tarquis, A. M.; Paz-Ferreiro, J.; Méndez, A.; Gascó, G.

    2014-03-01

    The effect of biochar on soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on soil CO2 emissions and in different physicochemical properties. For this purpose, a sandy-loam soil was amended with the three biochars (BI, BII and BIII) at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving's from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2) greater than 0.97. Results shown a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related with different biochar properties such as ash content, volatile matter, fixed carbon, organic carbon oxidised with dichromate, soluble carbon and metal and phenolic substances content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

  9. Factors driving carbon mineralization priming effect in a soil amended with different types of biochar

    Directory of Open Access Journals (Sweden)

    P. Cely

    2014-03-01

    Full Text Available The effect of biochar on soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on soil CO2 emissions and in different physicochemical properties. For this purpose, a sandy-loam soil was amended with the three biochars (BI, BII and BIII at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving's from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2 greater than 0.97. Results shown a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related with different biochar properties such as ash content, volatile matter, fixed carbon, organic carbon oxidised with dichromate, soluble carbon and metal and phenolic substances content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

  10. Arsenate removal from aqueous solution by cellulose-carbonated hydroxyapatite nanocomposites

    International Nuclear Information System (INIS)

    Microwave-assisted synthesis of the cellulose-carbonated hydroxyapatite nanocomposites (CCHA) with CHA nanostructures dispersed in the cellulose matrix was carried out by using cellulose solution, CaCl2, and NaH2PO4. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH-urea aqueous solution. Study was carried out to evaluate the feasibility of synthetic CCHA for As(V) removal from aqueous solution. Batch experiments were performed to investigate effects of various experimental parameters such as contact time (5 min - 8 h), initial As(V) concentration (1-50 mg/L), temperature (25, 35 and 45 oC), pH (2-10) and the presence of competing anions on As(V) adsorption on the synthetic CCHA. Kinetic data reveal that the uptake rate of As(V) was rapid at the beginning and equilibrium was achieved within 1 h. The adsorption process was well described by pseudo-first-order kinetics model. The adsorption data better fitted Langmuir isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was up to 12.72 mg/g. Thermodynamic study indicates an endothermic nature of adsorption and a spontaneous and favorable process. The optimum pH for As(V) removal was broad, ranging from 4 to 8. The As(V) adsorption was impeded by the presence of SiO32-, followed by PO43- and NO3-. The adsorption process appeared to be controlled by the chemical process.

  11. Batch, Kinetic and Equilibrium Studies of Chromium (Vi From Aqueous Phase Using Activated Carbon Derived From Lantana Camara Fruit

    Directory of Open Access Journals (Sweden)

    K. Nithya

    2015-12-01

    Full Text Available Batch experiments have been conducted to determine the maximum adsorption capacity of activated carbon derived from Lantana camara fruit to remove hexavalent chromium from aqueous solution. The removal efficiency and uptake capacity of the biosorbent were determined by varying several batch level parameters. Highest removal efficiency of the biosorbent was found to be almost 99% under optimal conditions. Maximum monolayer adsorption capacity was determined to be 86 mg/g. The experimental data best fitted with Langmuir adsorption isotherm and pseudo second order model. These findings conclude that the selected biosorbent has more promising features in binding hexavalent chromium in aqueous media.

  12. Carbon and nitrogen pools and mineralization rates in boreal forest soil after stump harvesting

    Science.gov (United States)

    Kaarakka, Lilli; Hyvönen, Riitta; Strömgren, Monika; Palviainen, Marjo; Persson, Tryggve; Olsson, Bengt A.; Helmisaari, Heljä-Sisko

    2016-04-01

    The use of forest-derived biomass has steadily increased in the Finland and Sweden during the past decades. Thus, more intensive forest management practices are becoming more common in the region, such as whole-tree harvesting, both above- and belowground. Stump harvesting causes a direct removal of carbon (C) in the form of biomass from the stand and can cause extensive soil disturbance, which in turn can result in increased C mineralization. In this study, the effects of stump harvesting on soil C and nitrogen (N) mineralization, and soil surface disturbance were studied at two different clear-felled Norway spruce (Picea abies) stands in Central Finland. The treatments were conventional stem-only harvesting combined with mounding (WTH) and stump harvesting (i.e. complete tree harvesting) combined with mounding (WTH+S). Logging residues were removed from all study sites. Soil samples down to a depth of 20 cm were systematically collected from the different soil disturbance surfaces (undisturbed soil, the mounds and the pits) 12-13 years after final harvest. Soil samples were incubated in the laboratory to determine the C and N mineralization rates. In addition, total C and N pools were estimated for each disturbance class and soil layer. Soil C and N pools were lower following stump harvesting, however, no statistically significant treatment effect was detected. Instead, C mineralization responses to treatment intensity was site-specific. C/N-ratio and organic matter content were significantly affected by harvest intensity. The observed changes in C and N pools appear to be related to the intrinsic variation of the surface disturbance and soil characteristics, and harvesting per se, rather than treatment intensity. Long-term studies are however needed to draw long-term conclusions whether stump harvesting significantly changes soil C and nutrient dynamics.

  13. Carbon mineralization in mine tailing ponds amended with pig slurries and marble wastes

    Directory of Open Access Journals (Sweden)

    Raul Zornoza

    2012-07-01

    Full Text Available Effective application of organic residues to reclaim soils requires the optimization of the waste management to minimize CO2 emissions and optimize soil C sequestration efficiency. In this study, the short-term effects of pig slurry amendment alone and together with marble waste on organic matter mineralization in two tailing ponds from Cartagena-La Unión Mining District (SE Spain were investigated in a field remediation experiment. The treatments were: marble waste (MW, pig slurry (PS, marble waste + pig slurry (MW+PS, and control. Soil carbon mineralization was determined using a static chamber method with alkali absorption during 70 days. Soil respiration rates in all plots were higher the first days of the experiment owing to higher soil moisture and higher mean air temperature. MW plots followed the same pattern than control plots, with similar respiration rates. The addition of pig slurry caused a significant increase in the respiration rates, although in MW+PS plots, respiration rates were lower than in PS plots. The cumulative quantities of C-CO2 evolved from the pig slurry mineralization were fitted to a first-order kinetic model explaining 90% of the data. This model implies the presence of only one mineralisable pool (C0. The values of the index C0*constant rate/added C were similar for PS plots in both tailing ponds, but lower in the MW+PS treatment, suggesting that the application of marble reduces the degradability of the organic compounds present in the pig slurry. Thus, the application of marble wastes contributes to slow down the loss of organic matter by mineralization.

  14. Negative CO2 emissions via subsurface mineral carbonation in fractured peridotite

    Science.gov (United States)

    Kelemen, P. B.; Matter, J.

    2014-12-01

    Uptake of CO2 from surface water via mineral carbonation in peridotite can be engineered to achieve negative CO2 emissions. Reaction with peridotite, e.g., CO2 + olivine (A), serpentine (B) and brucite (C), forms inert, non-toxic, solid carbonates such as magnesite. Experimental studies show that A can be 80% complete in a few hours with 30 micron powders and elevated P(CO2) [1,2,3]. B is slower, but in natural systems the rate of B+C is significant [4]. Methods for capture of dilute CO2 via mineral carbonation [4,5,6,7] are not well known, though CO2 storage via mineral carbonation has been discussed for decades [8,9]. Where crushed peridotite is available, as in mine tailings, increased air or water flow could enhance CO2 uptake at a reasonable cost [4,5]. Here we focus on enhancing subsurface CO2 uptake from surface water flowing in fractured peridotite, in systems driven by thermal convection such as geothermal power plants. Return of depleted water to the surface would draw down CO2 from the air [6,7]. CO2 uptake from water, rate limited by flow in input and output wells, could exceed 1000 tons CO2/yr [7]. If well costs minus power sales were 0.1M to 1M and each system lasts 10 years this costs < 10 to 100 per ton CO2. As for other CCS methods, upscaling requires infrastructure resembling the oil industry. Uptake of 1 Gt CO2/yr at 1000 t/well/yr requires 1M wells, comparable to the number of producing oil and gas wells in the USA. Subsurface CO2 uptake could first be applied in coastal, sub-seafloor peridotite with onshore drilling. Sub-seafloor peridotite is extensive off Oman, New Caledonia and Papua New Guinea, with smaller amounts off Spain, Morocco, USA, etc. This would be a regional contribution, used in parallel with other methods elsewhere. To achieve larger scale is conceivable. There is a giant mass of seafloor peridotite along slow-spreading mid-ocean ridges. Could robotic drills enhance CO2 uptake at a reasonable cost, while fabric chimneys

  15. Mineral solubilities in aqueous fluids at high pressures and temperatures: New thermodynamic model and implications for mass transfer in the Earth's crust and mantle

    Science.gov (United States)

    Dolejš, David; Manning, Craig E.

    2010-05-01

    Aqueous fluids are produced by metamorphic devolatilization and magmatic activity in a variety of settings including continental orogens, subduction zones with magmatic arcs as well as oceanic ridges and sea floor. They are responsible for mobility and transport of inorganic and organic solutes as manifested by alteration or veining, distinct element depletion-enrichment patterns or isotopic disturbances. The impact of many fluid-mediated processes is promoted by high time-integrated fluid fluxes, 101-106 m3 m-2, inferred for diffuse and focused fluid flow through lithosphere. Previous approaches to aqueous speciation have almost exclusively been based on the Helgeson-Kirkham-Flowers equation of state, which, however, suffers from inaccuracies in the vicinity of critical point of water and cannot be extrapolated to very high temperatures and pressures due to the lack of experimental data on dielectric constant of H2O. We propose a new thermodynamic model for dissolution of minerals in aqueous fluids at high temperatures and pressures, which is derived from individual energetic contributions to lattice breakdown, solute hydration and compression of the hydration shell. The thermodynamic properties depend on temperature and H2O density only and are calculated using three to five model parameters calibrated by experimental data. Our formulation of the density dependence has the advantage of behaving as a smooth function at the critical point of H2O, it closely corresponds to the generalized Krichevskii parameter, and it linearly correlates with the Born electrostatic energy. Solubilities of quartz, corundum, rutile, calcite, apatite, fluorite, and portlandite monotonously increase for a given phase by 4-5 orders of magnitude as temperature rises from 200 to 1100 oC along typical geotherms. At constant pressure, however, mineral solubilities initially increase with rising temperature, but subsequently drop. This effect results from a reversal in isobaric expansivity of

  16. Trace and Rare Earth Element Geochemistry of Micrite Mound Carbonates and Other Related REE Mineralized Carbonates from Bayan Obo Area in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    Yang Xiaoyong; Zheng Yongfei; Yang Xueming; Zhang Yuxu; Peng Yang; Qiu Liwen

    2005-01-01

    Geochemical study on trace and rare earth element geochemistry was carried out for different carbonates including the very REE-rich ones in the main ore bodies, a carbonatite dyke and two micrite mounds from Heilaobao far away from the Bayan Obo ore deposit, and Xishan in west Beijing. The results show that both carbonatite dyke and REE mineralized carbonates (dolomite and marble) in the main ore bodies and outside ore bodies have similarities to each other, with very extreme positive anomaly of Ba, Th, Nb, La, Ce, Nd, Sm, Pb, medium positive anomaly of Y, Ho, Tb, Er, Yb and negative anomaly of Sc, Ti and Cu. The REE concentration in the mineralized carbonates changes greatly, the total REE content changes from 262×10-6 in both east and west ore deposits to 104562 ×10-6 (10.46%), which is relatively lower than those samples of carbonatite dyke, whose REE contents vary greatly, from 1% up to 20 % of mass fraction. Light REE in the carbonatites are enriched and highly fractionated relative to heavy REE and there is no Eu anomaly. The REE distribution patterns of both mineralized carbonate and carbonatite dyke are of some similarities. However, the sedimentary carbonate micrite of Salinhudong Group in Heilaobao far outside the ore bodies and the pure carbonates from Xishan in Beijing, central part of North China plate, have the similarities in REE distributions with much lower REE contents, which are significantly different from those of carbonatite dyke and REE mineralized carbonate. In Bayan Obo district, both carbonates in the ore deposit and micrite mound outside the ore deposit underwent widespread metasomatism by fluids that resulted in formation of the superlager Fe-Nb-REE mineralization. It appears that the carbonates represent the evolution products of different geological stages.

  17. Application of carbonated apatite coating on a Ti substrate by aqueous spray method

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Chihiro; Hara, Hiroki [Division of Liberal Arts, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan); Takano, Ichiro [Department of Electrical Engineering, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan); Hayakawa, Tohru [Department of Dental Engineering, Tsurumi University School of Dental Medicine, Tsurumi, Yokohama City, Kanagawa 230-8501 (Japan); Sato, Mitsunobu, E-mail: lccsato@cc.kogakuin.ac.jp [Division of Liberal Arts, Kogakuin University, 2665-1, Nakano, Hachioji, Tokyo 192-0015 (Japan)

    2013-03-01

    The fabrication and characterization of a carbonate-containing apatite film deposited on a Ti plate via an aqueous spray method is described. The mist of the spray solution emitted from a perpendicularly oriented airbrush was made to strike a warmed Ti substrate. The thicknesses of the sprayed film and those heat-treated at 400 Degree-Sign C-700 Degree-Sign C under Ar gas flow were in the range 1.21-1.40 {mu}m. The results of elemental analyses and Fourier transform infrared spectroscopy of the powders that were mechanically collected from the surface of the sprayed film suggest that the film was Ca{sub 10}(PO{sub 4})6(CO{sub 3}) {center_dot} 2CO{sub 2} {center_dot} 3H{sub 2}O. The presence of the carbonate ion and the lattice CO{sub 2} molecule was confirmed via the aforementioned analyses; the finding was also consistent with the X-ray diffraction patterns of the films and the chemical identity of the sprayed and heat-treated films that were measured using X-ray photoelectron spectroscopy. The sprayed film comprises a characteristic network structure, which contains round particles within the networks, as was observed by field-emission scanning electron microscopy. A scratch test indicated that the shear stress of the sprayed film (21 MPa) significantly improved to 40 and > 133 MPa after heat-treatment at 600 Degree-Sign C and 700 Degree-Sign C, respectively, under Ar gas flow for 10 min. - Highlights: Black-Right-Pointing-Pointer CO{sub 2} inserted CA films were fabricated on a Ti plate by the aqueous spray method. Black-Right-Pointing-Pointer The characteristic network structure of the sprayed film was clarified by FE-SEM. Black-Right-Pointing-Pointer Ca{sub 10}(PO{sub 4})6(CO{sub 3}) {center_dot} 2CO{sub 2} {center_dot} 3H{sub 2}O film with a thickness of ca. 1 {mu}m could be deposited. Black-Right-Pointing-Pointer A well-adhered film with shear stress of 21 MPa was obtained at low temperatures. Black-Right-Pointing-Pointer A stable solution for VOC

  18. Application of carbonated apatite coating on a Ti substrate by aqueous spray method

    International Nuclear Information System (INIS)

    The fabrication and characterization of a carbonate-containing apatite film deposited on a Ti plate via an aqueous spray method is described. The mist of the spray solution emitted from a perpendicularly oriented airbrush was made to strike a warmed Ti substrate. The thicknesses of the sprayed film and those heat-treated at 400 °C–700 °C under Ar gas flow were in the range 1.21–1.40 μm. The results of elemental analyses and Fourier transform infrared spectroscopy of the powders that were mechanically collected from the surface of the sprayed film suggest that the film was Ca10(PO4)6(CO3) · 2CO2 · 3H2O. The presence of the carbonate ion and the lattice CO2 molecule was confirmed via the aforementioned analyses; the finding was also consistent with the X-ray diffraction patterns of the films and the chemical identity of the sprayed and heat-treated films that were measured using X-ray photoelectron spectroscopy. The sprayed film comprises a characteristic network structure, which contains round particles within the networks, as was observed by field-emission scanning electron microscopy. A scratch test indicated that the shear stress of the sprayed film (21 MPa) significantly improved to 40 and > 133 MPa after heat-treatment at 600 °C and 700 °C, respectively, under Ar gas flow for 10 min. - Highlights: ► CO2 inserted CA films were fabricated on a Ti plate by the aqueous spray method. ► The characteristic network structure of the sprayed film was clarified by FE-SEM. ► Ca10(PO4)6(CO3) · 2CO2 · 3H2O film with a thickness of ca. 1 μm could be deposited. ► A well-adhered film with shear stress of 21 MPa was obtained at low temperatures. ► A stable solution for VOC-free spraying was facilely prepared.

  19. Carbon dioxide exchange of a perennial bioenergy crop cultivation on a mineral soil

    Science.gov (United States)

    Lind, Saara E.; Shurpali, Narasinha J.; Peltola, Olli; Mammarella, Ivan; Hyvönen, Niina; Maljanen, Marja; Räty, Mari; Virkajärvi, Perttu; Martikainen, Pertti J.

    2016-03-01

    One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinacea L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 exchange of this RCG cultivation system, and to understand the key factors controlling its CO2 exchange, the net ecosystem CO2 exchange (NEE) was measured from July 2009 until the end of 2011 using the eddy covariance (EC) method. The RCG cultivation thrived well producing yields of 6200 and 6700 kg DW ha-1 in 2010 and 2011, respectively. Gross photosynthesis (GPP) was controlled mainly by radiation from June to September. Vapour pressure deficit (VPD), air temperature or soil moisture did not limit photosynthesis during the growing season. Total ecosystem respiration (TER) increased with soil temperature, green area index and GPP. Annual NEE was -262 and -256 g C m-2 in 2010 and 2011, respectively. Throughout the study period from July 2009 until the end of 2011, cumulative NEE was -575 g C m-2. Carbon balance and its regulatory factors were compared to the published results of a comparison site on drained organic soil cultivated with RCG in the same climate. On this mineral soil site, the RCG had higher capacity to take up CO2 from the atmosphere than on the comparison site.

  20. Development of a technology for obtaining flotation reagent oxane-3 for carbon mineral raw materials of Kazakhstan

    OpenAIRE

    Sergey Kalugin; Zhuldyz Shildebaeva; Madina Mametzhanova; Nazym Yelibaeva; Sergey Efremov; Sergey Nechipurenko; Dana Omarova

    2014-01-01

    The paper represents the results of development of a technology for obtaining oxane-3 and its application for enrichment of carbon mineral raw materials. Studies on enrichment of a shungite rock showed that the increase of a pulp temperature to 30°C significantly improves the characteristics and rate of the flotation process. Measured indicators of a shungite rock enrichment using Flotol B were lower in comparison with an enrichment by oxane-3. For schungite mineral, it was established that t...

  1. Calculating carbon mass balance from unsaturated soil columns treated with CaSO₄₋minerals: test of soil carbon sequestration.

    Science.gov (United States)

    Han, Young-Soo; Tokunaga, Tetsu K

    2014-12-01

    Renewed interest in managing C balance in soils is motivated by increasing atmospheric concentrations of CO2 and consequent climate change. Here, experiments were conducted in soil columns to determine C mass balances with and without addition of CaSO4-minerals (anhydrite and gypsum), which were hypothesized to promote soil organic carbon (SOC) retention and soil inorganic carbon (SIC) precipitation as calcite under slightly alkaline conditions. Changes in C contents in three phases (gas, liquid and solid) were measured in unsaturated soil columns tested for one year and comprehensive C mass balances were determined. The tested soil columns had no C inputs, and only C utilization by microbial activity and C transformations were assumed in the C chemistry. The measurements showed that changes in C inventories occurred through two processes, SOC loss and SIC gain. However, the measured SOC losses in the treated columns were lower than their corresponding control columns, indicating that the amendments promoted SOC retention. The SOC losses resulted mostly from microbial respiration and loss of CO2 to the atmosphere rather than from chemical leaching. Microbial oxidation of SOC appears to have been suppressed by increased Ca(2+) and SO4(2)(-) from dissolution of CaSO4 minerals. For the conditions tested, SIC accumulation per m(2) soil area under CaSO4-treatment ranged from 130 to 260 g C m(-1) infiltrated water (20-120 g C m(-1) infiltrated water as net C benefit). These results demonstrate the potential for increasing C sequestration in slightly alkaline soils via CaSO4-treatment. PMID:24974014

  2. Stabilization of carbon dioxide (CO2) bubbles in micrometer-diameter aqueous droplets and the formation of hollow microparticles.

    Science.gov (United States)

    Lu, Tianyi; Fan, Rong; Delgadillo, Luis F; Wan, Jiandi

    2016-04-26

    We report an approach to stabilize carbon dioxide (CO2) gas bubbles encapsulated in micrometer-diameter aqueous drops when water in the aqueous drops is evaporated. CO2-in-water-in-oil double emulsion drops are generated using microfluidic approaches and evaporation is conducted in the presence of sodium dodecyl sulfate (SDS), poly(vinyl alcohol) (PVA) and/or graphene oxide (GO) particles dispersed in the aqueous phase of the double emulsion drops. We examine the roles of the bubble-to-drop size ratio, PVA and GO concentration in the stabilization of CO2 bubbles upon water evaporation and show that thin-shell particles with encapsulated CO2 bubbles can be obtained under optimized conditions. The developed approach offers a new strategy to study CO2 dissolution and stability on the microscale and the synthesis of novel gas-core microparticles. PMID:27025654

  3. Mineralization of herbicide 3,6-dichloro-2-methoxybenzoic acid in aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton

    International Nuclear Information System (INIS)

    The mineralization of acidic aqueous solutions with 230 and 115 ppm of herbicide 3,6-dichloro-2-methoxybenzoic acid (dicamba) in 0.05 M Na2SO4 of pH 3.0 has been studied by electro-Fenton and photoelectro-Fenton using a Pt anode and an O2-diffusion cathode, where oxidizing hydroxyl radicals are produced from Fenton's reaction between added Fe2+ and H2O2 generated by the cathode. While electro-Fenton only yields 60-70% mineralization, photoelectro-Fenton allows a fast and complete depollution of herbicide solutions, even at low currents, by the action of UV irradiation. In both treatments, the initial chlorine is rapidly released to the medium as chloride ion. Comparative electrolyses by anodic oxidation in the absence and presence of electrogenerated H2O2 give very poor degradation. The dicamba decay follows a pseudo-first-order reaction, as determined by reverse-phase chromatography. Formic, maleic and oxalic acids have been detected in the electrolyzed solutions by ion-exclusion chromatography. In electro-Fenton, all formic acid is transformed into CO2, and maleic acid is completely converted into oxalic acid, remaining stable Fe3+-oxalato complexes in the solution. The fast mineralization of such complexes by UV light explains the highest oxidative ability of photoelectro-Fenton

  4. Carbonate-hosted nonsulphide Zn-Pb mineralization of southern British Columbia, Canada

    Science.gov (United States)

    Paradis, Suzanne; Keevil, Halley; Simandl, George J.; Raudsepp, Mati

    2015-12-01

    Many carbonate-hosted sulphide deposits in the Salmo district of southern British Columbia have near-surface Zn- and Pb-bearing iron oxide-rich gossans. The gossans formed when carbonate-hosted, base metal sulphides were subjected to intense supergene weathering processes and metals were liberated by the oxidation of sulphide minerals. Two types of supergene carbonate-hosted nonsulphide deposits, direct replacement (`red ore') and wallrock replacement (`white ore'), are present in the Salmo district. The direct replacement deposits formed by the oxidation of primary sulphides; the base metals passed into solution and were redistributed and trapped within the space occupied by the oxidized portion of the sulphide protore. Depending on the extent of replacement of the sulphides by Zn-, Pb- and Fe-bearing oxides, silicates, carbonates and phosphates, the resulting ore can be called `mixed' (sulphides and nonsulphides) or simply `nonsulphide'. The wallrock replacement deposits formed when base metals liberated by the oxidation of sulphides were transported by circulating supergene solutions down and/or away from the sulphides to form wallrock replacement deposits. The direct replacement nonsulphide zones of the Salmo district overlay the sulphide bodies in which they replaced the sulphides and carbonates, forming large irregular replacement masses, encrustations and open-space fillings. They consist predominantly of hematite, goethite, hemimorphite [Zn4Si2O7(OH)2·H2O], minor hydrozincite [Zn5(CO3)2(OH)6], cerussite [PbCO3] and traces of willemite [Zn2SiO4]. The wallrock replacement zones consist mainly of hemimorphite with local occurrences of iron oxides, hopeite [Zn3(PO4)2·4H2O] and tarbuttite [Zn2(PO4)(OH)]. No remnants of sulphides were observed in the replacement zones. The Salmo nonsulphide deposits were formed by prolonged weathering of Mississippi Valley-type (MVT) mineralization that underwent dissolution and oxidation of the pyrite, sphalerite and galena

  5. A green heterogeneous synthesis of N-doped carbon dots and their photoluminescence applications in solid and aqueous states

    Science.gov (United States)

    Xu, Minghan; He, Guili; Li, Zhaohui; He, Fengjiao; Gao, Feng; Su, Yanjie; Zhang, Liying; Yang, Zhi; Zhang, Yafei

    2014-08-01

    Compared with traditional semiconductor quantum dots (QDs) and organic dyes, photoluminescent carbon dots (CDs) are superior because of their high aqueous solubility, robust chemical inertness, facile functionalization, high resistance to photobleaching, low toxicity and good biocompatibility. Herein, a green, large-scale and high-output heterogeneous synthesis of N-doped CDs was developed by reacting calcium citrate and urea under microwave irradiation without the use of any capping agents. The obtained N-doped CDs with a uniform size distribution exhibit good aqueous solubility and yellowish-green fluorescence in the solid and aqueous states. These unique luminescence properties of N-doped CDs inspire new thoughts for applications as fluorescent powders, fluorescent inks, the growth of fluorescent bean sprouts, and fingerprint detection tools.Compared with traditional semiconductor quantum dots (QDs) and organic dyes, photoluminescent carbon dots (CDs) are superior because of their high aqueous solubility, robust chemical inertness, facile functionalization, high resistance to photobleaching, low toxicity and good biocompatibility. Herein, a green, large-scale and high-output heterogeneous synthesis of N-doped CDs was developed by reacting calcium citrate and urea under microwave irradiation without the use of any capping agents. The obtained N-doped CDs with a uniform size distribution exhibit good aqueous solubility and yellowish-green fluorescence in the solid and aqueous states. These unique luminescence properties of N-doped CDs inspire new thoughts for applications as fluorescent powders, fluorescent inks, the growth of fluorescent bean sprouts, and fingerprint detection tools. Electronic supplementary information (ESI) available: The photos of different precursors under daylight and 365 nm UV beam; 1H-NMR and Raman spectrum of N-doped CDs; toxicity study of bean sprouts; the correlation between length of bean sprouts and the concentration of N-doped CDs

  6. A simple synthesis method to produce metal oxide loaded carbon paper using bacterial cellulose gel and characterization of its electrochemical behavior in an aqueous electrolyte

    Science.gov (United States)

    Miyajima, Naoya; Jinguji, Ken; Matsumura, Taiyu; Matsubara, Toshihiro; Sakane, Hideto; Akatsu, Takashi; Tanaike, Osamu

    2016-04-01

    A simple synthetic chemical process to produce metal oxide loaded carbon papers was developed using bacterial cellulose gel, which consisted of nanometer-sized fibrous cellulose and water. Metal ions were successfully impregnated into the gel via aqueous solution media before drying and carbonization methods resulting in metal oxide contents that were easy to control through variations in the concentration of aqueous solutions. The papers loaded by molybdenum oxides were characterized as pseudocapacitor electrodes preliminary, and the large redox capacitance of the oxides was followed by a conductive fibrous carbon substrate, suggesting that a binder and carbon black additive-free electrode consisting of metal oxides and carbon paper was formed.

  7. Comparative performance of cement kiln dust and activated carbon in removal of cadmium from aqueous solutions.

    Science.gov (United States)

    El-Refaey, Ahmed A

    2016-01-01

    This study compared the performance of cement kiln dust (CKD) as industrial byproduct and commercially activated carbon (AC) as adsorbent derived from agricultural waste for the removal of cadmium (Cd(2+)) from aqueous solutions. CKD and AC were characterized by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) and surface areas demonstrate the differences of physicochemical properties. Batch equilibrium experiments were conducted for various intervals extended to 96 h at 20, 25 and 30°C to investigate the efficiency of the sorbents in the removal of Cd(2+). CKD expressed high affinity for removal of Cd(2+) and was not affected by temperature, while AC was significantly affected, which reflects dissimilarity in the retention mechanisms defendant in CKD and those pursued by AC. The results were explained by changes of FTIR and SEM images before and after sorption experiments. The suggestion is that electrostatic ion exchange and complex reactions are the main mechanisms for Cd(2+) removal. The kinetic data were evaluated by fractional power, Elovich, pseudo-first order and pseudo-second-order kinetic models. The pseudo-second-order kinetic model was found to correlate with the experimental data well. These results revealed that CKD can be used as a cost-effective and efficient sorbent for Cd(2+) removal in comparison with AC. PMID:27054742

  8. Atomic Force Microscopy of DNA-wrapped Single-walled Carbon Nanotubes in Aqueous Solution.

    Science.gov (United States)

    Hayashida, Takuya; Umemura, Kazuo

    2016-07-01

    We evaluated hybrids of DNA and single-walled carbon nanotubes (SWNTs) in aqueous solution and in air using atomic force microscopy (AFM). Although intensive AFM observations of these hybrids were previously carried out for samples in air, this is the first report on AFM observations of these hybrids in solution. As expected, diameters of DNA-SWNT hybrids dramatically increased in tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid (TE) buffer solution. The data suggest that DNA molecules maintain their structures even on the SWNT surfaces. Furthermore, we simultaneously observed single DNA-SWNT hybrids using three different AFM modes in air and in the TE buffer solution. Height value of the hybrids was largest in the solution, and lowest for the mode that repulsive force is expected in air. For the bare SWNT molecules, height differences among the three AFM modes were much lower than those of the DNA-SWNT hybrids. DNA molecules adsorbed on SWNT surfaces flexibly changed their morphology as well as DNA molecules on flat surfaces such as mica. This is hopeful results for biological applications of DNA-SWNT hybrids. In addition, our results revealed the importance of the single-molecule approach to evaluate DNA structures on SWNT surfaces. PMID:27045980

  9. 2-chlorophenol sorption from aqueous solution using granular activated carbon and polymeric adsorbents

    Science.gov (United States)

    Ghatbandhe, A. S.; Jahagirdar, H. G.; Yenkie, M. K. N.; Deosarkar, S. D.

    2013-08-01

    Adsorption equilibrium and kinetics of 2-chlorophenol (2-CP) one of the chlorophenols (CPs) onto bituminous coal based Filtrasorb-400 grade granular activated carbon and three different types of polymeric adsorbents were studied in aqueous solution in a batch system. Langmuir isotherm models were applied to experimental equilibrium data of 2-CP adsorption. Equilibrium data fitted very well to the Langmuir equilibrium models of 2-CP. Adsorbent monolayer capacity Q Langmuir constant b and adsorption rate constants k a were evaluated. 2-CP adsorption using GAC is very rapid in the first hour of contact where 70-80% of the adsorbate is removed by GAC followed by a slow approach to equilibrium. Whereas in case of polymeric adsorbents 60-65% of the adsorbate is removed in the first 30 min which is then followed by a slow approach to equilibrium. The order of adsorption of 2-CP on different adsorbents used in the study is found to be in following order: F-400 > XAD-1180 > XAD-4 > XAD-7HP.

  10. Directing carbon nanotubes from aqueous phase to o/w interface for heavy metal uptaking.

    Science.gov (United States)

    Gao, Lili; Yin, Huayi; Mao, Xuhui; Zhu, Hua; Xiao, Wei; Wang, Dihua

    2015-09-01

    Separation and reuse of dispersed nanoparticles are major obstacles to the extensive application of nano-sized absorbents in wastewater treatment. Herein, we demonstrate the capability of directing acid-oxidized carbon nanotubes (CNTs) as the transfer vehicles of heavy metal ions from simulated wastewater. The heavy metal-loaded CNTs can be readily separated from the aqueous phase via the aggregation process at an oil/water (o/w) interface. The minimum surfactant amount to achieve 99 % transfer ratio (Tr) of 100 mg/L CNTs from water phase to o/w interface was ∼0.01 mM. The adsorption experiments showed that the removal efficiency of the divalent lead ions increased with an increase in CNT mass, and the subsequent addition of cetyltrimethylammonium bromide (CTAB) surfactant did not negatively impact the removal of soluble divalent lead species (Pb(II)). In a wide region of pH and ionic strength, both the decontamination of Pb(II) and the transfer of CNTs from water phase to o/w interface can be accomplished successively. The method presented in this study may be developed as a generic one for collecting or recycling the pollutant-loaded nano-sized absorbents. PMID:25966885

  11. Removal of Cd+2 from aqueous solutions onto polypyrrole coated reticulated vitreous carbon eletrodes

    Directory of Open Access Journals (Sweden)

    Jucelânia Tramontina

    2001-07-01

    Full Text Available The development of simple methods for removal of heavy metals from aqueous samples is a relevant field of research. In this connection, the electrodeposition of the Cd+2 ion, one of the most toxic species for animals and human beings, was investigated in aerated pH 4.8 sulfuric-sulfate solutions. In potentiostatic conditions, the maximum rate of cadmium deposition at a neutral polypyrrole (PPy0 coated reticulated vitreous carbon (RVC working electrode occurs at -3.0 V vs. the saturated calomel reference electrode (SCE. Moreover, the conversion rate depends both on the applied potential and on the mass transport regime, and, for solutions containing 10 mg L-1 of Cd2+, the highest removal efficiency achieved is 84% after 90 min of electrolysis. The concentration decay of the Cd+2 ion in the solution was monitored by anodic stripping voltammetry (ASV at a hanging mercury drop electrode. Besides, metallic cadmium deposited onto the polypyrrole modified RVC electrode was evidenced by Scanning Electron Microscopy (SEM analysis using the backscattered electron image (BEI technique and by Energy Dispersive Spectrometry (EDS.

  12. Evaluating Stability of Aqueous Multiwalled Carbon Nanotube Nanofluids by Using Different Stabilizers

    Directory of Open Access Journals (Sweden)

    Tun-Ping Teng

    2014-01-01

    Full Text Available The 0.5 wt.% multiwalled carbon nanotubes/water nanofluids (MWNFs were produced by using a two-step synthetic method with different types and concentrations of stabilizers. The static position method, centrifugal sedimentation method, zeta potential measurements, and rheological experiments were used to assess the stability of the MWNFs and to determine the optimal type and fixed MWCNTs-stabilizer concentration of stabilizer. Finally, MWNFs with different concentrations of MWCNTs were produced using the optimal type and fixed concentration ratio of stabilizer, and their stability, thermal conductivity, and pH were measured to assess the feasibility of using them in heat transfer applications. MWNFs containing SDS and SDBS with MWCNTs-stabilizer concentration ratio were 5 : 2 and 5 : 4, respectively, showed excellent stability when they were evaluated by static position, centrifugal sedimentation, zeta potential, and rheological experiments at the same time. The thermal conductivity of the MWNFs indicated that the most suitable dispersing MWNF contained SDBS. MWNFs with MWCNTs concentrations of 0.25, 0.5, and 1.0 wt.% were fabricated using an aqueous SDBS solution. In addition, the thermal conductivity of the MWNFs was found to have increased, and the thermal conductivity values were greater than that of water at 25°C by 3.20%, 8.46%, and 12.49%.

  13. Removal Mechanism of Aqueous Lead by a Novel Eco-material:Carbonate Hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    Huanyan XU; Lei YANG; Peng WANG; Yu LIU; Mingsheng PENG

    2007-01-01

    Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite (CHap) are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage increases with decreasing pH values and reaches a maximum at pH=2-3. Under some conditions,the lead residual concentration is below national integrated wastewater discharge standard, even drinking water standard. The removal behavior is a complicated non-homogeneous solid/liquid reaction, which can be described by two stages from kinetic point of view. At the earlier stage, reaction rate is so fast that its kinetic course is intricate, which requires further study. At the latter stage, the rate of reaction becomes slow and the process of reaction accords with one order reaction kinetic equation. Experimental results show that the relationship between reaction rate constant k1 and temperature T accords to Arrhenius Equation, and the activation energy of sorption (Ea) is 11.93 k J/mol and frequency factor (A) is 2.51 s-1. X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive X-ray fluoresence spectrometer (SEM-EDS) and toxicity characteristic leaching procedure (TCLP) test were conducted in this work. It is indicated that the main mechanism is dissolution-precipitation, accompanying with superficial sorption.

  14. Kinetic research on the sorption of aqueous lead by synthetic carbonate hydroxyapatite.

    Science.gov (United States)

    Xu, HuanYan; Yang, Lei; Wang, Peng; Liu, Yu; Peng, MingSheng

    2008-01-01

    The sorption of aqueous lead on carbonate-hydroxyapatite (CHAp) is a complicated non-homogeneous solid/water reaction, which from the kinetic point of view has two stages. In the first stage, the reaction rate is so fast and the kinetic pathway so intricate that further research is required. In the second stage, the reaction rate slows down and the reaction process follows that of a first-order kinetic equation. Experimental results show that the relationship between the reaction rate constant k(1) and temperature T agrees with the Arrhenius equation, and that the activation energy of sorption (E(a)) is 11.93 kJ/mol and the frequency factor (A) is 2.51/s. The reaction rate constant k(1) increases with the Pb(2+) initial concentration and decreasing pH, but with increasing CHAp dosage. X-ray diffraction (XRD), scanning electron microscopy with energy dispersion spectrum (SEM-EDS) and toxicity characteristic leaching procedure (TCLP) tests indicate that the main sorption mechanism is dissolution-precipitation, in conjunction with surface sorption. PMID:17360101

  15. Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

    KAUST Repository

    Zeng, Hongbo

    2011-06-07

    Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

  16. The corrosion of carbon steel in aqueous lithium hydroxide under a hydrogen blanket

    International Nuclear Information System (INIS)

    The corrosion behavior of carbon steel in 3 and 5 mol/L aqueous solutions of lithium hydroxide at 95 degrees C under a hydrogen atmosphere was investigated in immersion tests lasting ten days. Corrosion rates were determined by wight loss, and the corrosion products were characterized by bulk chemical analysis, by light and electron microscopy, and by powder X-ray diffraction. Corrosion was uniform and the corrosion rates were moderately high (0.42 mm/y in 3 mol/L and 0.56 mm/y in 5 mol/L). The corrosion products consisted of a mixture of well-formed, octahedral crystals, and poorly crystallized masses and spherules that formed by precipitation from solution. These products formed a scale on the metal surface that continually sloughed off and afforded only minor protection. Both phases were identified as lithium-iron oxides, each possessing a disordered, non-stoichiometric structure. The predominant phase was a magnetic spinel LiFe508 and the minor phase was LiFe02. A corrosion mechanism is outlined. (2 figs., 5 tabs., 20 refs.)

  17. Effective Degradation of Aqueous Tetracycline Using a Nano-TiO2/Carbon Electrocatalytic Membrane

    Directory of Open Access Journals (Sweden)

    Zhimeng Liu

    2016-05-01

    Full Text Available In this work, an electrocatalytic membrane was prepared to degrade aqueous tetracycline (TC using a carbon membrane coated with nano-TiO2 via a sol-gel process. SEM, XRD, EDS, and XPS were used to characterize the composition and structure of the electrocatalytic membrane. The effect of operating conditions on the removal rate of tetracycline was investigated systematically. The results show that the chemical oxygen demand (COD removal rate increased with increasing residence time while it decreased with increasing the initial concentration of tetracycline. Moreover, pH had little effect on the removal of tetracycline, and the electrocatalytic membrane could effectively remove tetracycline with initial concentration of 50 mg·L−1 (pH, 3.8–9.6. The 100% tetracycline and 87.8% COD removal rate could be achieved under the following operating conditions: tetracycline concentration of 50 mg·L−1, current density of 1 mA·cm−2, temperature of 25 °C, and residence time of 4.4 min. This study provides a new and feasible method for removing antibiotics in water with the synergistic effect of electrocatalytic oxidation and membrane separation. It is evident that there will be a broad market for the application of electrocatalytic membrane in the field of antibiotic wastewater treatment.

  18. Removal of Ni2+ from Aqueous Solutions by Adsorption Onto Magnetic Multiwalled Carbon Nanotube Nanocomposite

    Directory of Open Access Journals (Sweden)

    Konicki Wojciech

    2014-06-01

    Full Text Available The removal of Ni2+ from aqueous solution by magnetic multiwalled carbon nanotube nanocomposite (MMWCNTs-C was investigated. MMWCNTs-C was characterized by X-ray Diffraction method (XRD, High-Resolution Transmission Electron Microscopy (HRTEM, surface area (BET, and Fourier Transform-Infrared Spectroscopy (FTIR. The effects of initial concentration, contact time, solution pH, and temperature on the Ni2+ adsorption onto MMWCNTs-C were studied. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 2.11 mg g–1. The adsorption kinetics was best described by the pseudo-second-order model. The thermodynamic parameters, such as ΔHo, ΔGo and ΔSo, were also determined and evaluated. The adsorption of Ni2+ is generally spontaneous and thermodynamically favorable. The values of ΔHo and ΔGo indicate that the adsorption of Ni2+ onto MMWCNTs-C was a physisorption process.

  19. Arsenic adsorption by polyvinyl pyrrolidone K25 coated cassava peel carbon from aqueous solution

    International Nuclear Information System (INIS)

    Sorption of arsenic from aqueous solution was carried out using polyvinyl pyrrolidone K25 coated cassava peel carbon (PVPCC). Batch experiments were conducted to determine the effect of contact time, initial concentration, pH and desorption. Batch sorption data's were fitted to Lagergren kinetic studies. Column studies were also conducted using PVPCC as adsorbent. The optimized flow rate of 2.5 mL min-1 and bed height 10 cm were used to determine the effect of metal ion concentration on removal of As(V). BDST model was applied to calculate the adsorption capacity (N0) of column. The N0 value of 2.59 x 10-5, 4.21 x 10-5, 4.05 x 10-5, 4.26 x 10-5 and 3.2 x 10-5 mg g-1 were obtained for 0.5, 1.0, 1.5, 2.0 and 2.5 mg L-1 of As(V), respectively. The batch sorption proved to be more efficient than the column sorption. The sorption of As(V) and the nature of the adsorbent was examined by Fourier transmission infrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies, respectively

  20. Analysis of Solid and Aqueous Phase Products from Hydrothermal Carbonization of Whole and Lipid-Extracted Algae

    Directory of Open Access Journals (Sweden)

    Amber Broch

    2013-12-01

    Full Text Available Microalgae have tremendous potential as a feedstock for production of liquid biofuels, particularly biodiesel fuel via transesterification of algal lipids. However, biodiesel production results in significant amounts of algal residues, or “lipid extracted algae” (LEA. Suitable utilization of the LEA residue will improve the economics of algal biodiesel. In the present study, we evaluate the hydrothermal carbonization (HTC of whole and lipid extracted algal (Spirulina maxima feedstocks in order to produce a solid biofuel (hydrochar and value-added co-products in the aqueous phase. HTC experiments were performed using a 2-L Parr reactor (batch type at 175–215 °C with a 30-min holding time. Solid, aqueous and gaseous products were analyzed using various laboratory methods to evaluate the mass and carbon balances, and investigate the existence of high value chemicals in the aqueous phase. The HTC method is effective in creating an energy dense, solid hydrochar from both whole algae and LEA at lower temperatures as compared to lignocellulosic feedstocks, and is effective at reducing the ash content in the resulting hydrochar. However, under the treatment temperatures investigated, less than 1% of the starting dry algae mass was recovered as an identified high-value chemical in the aqueous phase.

  1. Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

    OpenAIRE

    Ehlmann, B. L.; Bish, D. L.; Ruff, S. W.; Mustard, J. F.

    2012-01-01

    We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separ...

  2. Investigation of the potential of coal combustion fly ash for mineral sequestration of CO2 by accelerated carbonation

    International Nuclear Information System (INIS)

    Mineral carbonation of alkaline waste materials is being studied extensively for its potential as a way of reducing the increased level of CO2 in the atmosphere. Carbonation converts CO2 into minerals which are stable over geological time scales. This process occurs naturally but slowly, and needs to be accelerated to offset the present rate of emissions from power plants and other emission sources. The present study attempts to identify the potential of coal fly ash as a source for carbon storage (sequestration) through ex-situ accelerated mineral carbonation. In the study, two operational parameters that could affect the reaction process were tested to investigate their effect on mineralization. Coal fly ash was mixed with water to different water-to-solid ratios and samples were carbonated in a pressure vessel at different initial CO2 pressures. Temperature was kept constant at 40 °C. According to the results, one ton of Hazelwood fly ash could sequester 7.66 kg of CO2. The pressure of CO2 inside the vessel has an effect on the rate of CO2 uptake and the water-to-solid ratio affects the weight gain after the carbonation of fly ash. The results confirm the possibility of the manipulation of process parameters in enhancing the carbonation reaction. - Highlights: ► Mineral sequestration CO2 by of coal fly ash is a slow process under ambient conditions. ► It can be accelerated by manipulating the process parameters inside a reactor. ► Initial CO2 pressure and water to solid mixing ratio inside the reactor are two of those operational parameters. ► According to the test results higher CO2 initial pressure gives higher on rates of CO2 sequestration. ► Water to fly ash mixing ratio effect on amount of CO2 sequestered into fly ash

  3. Modulation of the initial mineralization process of SaOS-2 cells by carbonic anhydrase activators and polyphosphate.

    Science.gov (United States)

    Wang, Xiaohong; Schröder, Heinz C; Schlossmacher, Ute; Neufurth, Meik; Feng, Qingling; Diehl-Seifert, Bärbel; Müller, Werner E G

    2014-05-01

    Ca-phosphate/hydroxyapatite (HA) crystals constitute the mineral matrix of vertebrate bones, while Ca-carbonate is the predominant mineral of many invertebrates, like mollusks. Recent results suggest that CaCO₃ is also synthesized during early bone formation. We demonstrate that carbonic anhydrase-driven CaCO₃ formation in vitro is activated by organic extracts from the demosponge Suberites domuncula as well as by quinolinic acid, one component isolated from these extracts. Further results revealed that the stimulatory effect of bicarbonate (HCO₃ (-)) ions on mineralization of osteoblast-like SaOS-2 cells is strongly enhanced if the cells are exposed to inorganic polyphosphate (polyP), a linear polymer of phosphate linked by energy-rich phosphodiester bonds. The effect of polyP, administered as polyP (Ca²⁺ salt), on HA formation was found to be amplified by addition of the carbonic anhydrase-activating sponge extract or quinolinic acid. Our results support the assumption that CaCO₃ deposits, acting as bio-seeds for Ca-carbonated phosphate formation, are formed as an intermediate during HA mineralization and that the carbonic anhydrase-mediated formation of those deposits is under a positive-negative feedback control by bone alkaline phosphatase-dependent polyP metabolism, offering new targets for therapy of bone diseases/defects. PMID:24374859

  4. Preparation and characteristics of carbon-supported platinum catalyst and its application in the removal of phenolic pollutants in aqueous solution by microwave-assisted catalytic oxidation

    International Nuclear Information System (INIS)

    Granular activated carbon-supported platinum (Pt/GAC) catalysts were prepared by microwave irradiation and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Pt particles dispersing onto the surface of GAC could be penetrated by microwave and acted as 'reaction centre' in the degradations of p-nitrophenol (PNP) and pentachlorophenol (PCP) in aqueous solution by microwave-assisted catalytic oxidation. The reaction was carried out through a packed bed reactor under ambient pressure and continuous flow mode. Under the conditions of microwave power 400 W, influent flow 6.4 mL min-1 and air flow 120 mL min-1, phenolic solutions with high concentration (initial concentrations of PNP and PCP solutions were 1469 and 1454 mg L-1, respectively) were treated effectively by Pt/GAC, 86% PNP and 90% PCP were degraded and total organic carbon (TOC) removal reached 85% and 71%, respectively. Compared with GAC, loaded Pt apparently accelerated oxidative reaction so that Pt/GAC had a better degrading and mineralizing efficiencies for PNP. Hydraulic retention time was only 16 min in experiment, which was shortened greatly compared with catalytic wet air oxidation. Pyrolysis and oxidation of phenolic pollutants occurred simultaneously on the surface of Pt/GAC by microwave irradiation

  5. Adsorption of Hexavalent Chromium from Aqueous Solution Using Chemically Activated Carbon Prepared from Locally Available Waste of Bamboo (Oxytenanthera abyssinica)

    OpenAIRE

    Dula, Tamirat; Siraj, Khalid; Kitte, Shimeles Addisu

    2014-01-01

    This study reports on the adsorption of Hexavalent Chromium from aqueous solutions using activated carbon prepared from bamboo (Oxytenanthera abyssinica) waste by KOH activation heating in an electrical furnace at 1073 K for 3 hrs. Batch adsorption experiments were also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order k...

  6. Biomimetic mineralization of calcium carbonate/carboxymethylcellulose microspheres for lysozyme immobilization

    International Nuclear Information System (INIS)

    Porous calcium carbonate/carboxymethylcellulose (CaCO3/CMC) microspheres were prepared by the biomimetic mineralization method for lysozyme immobilization via adsorption. The size and morphology of CaCO3/CMC microspheres were characterized by transmitted electron microscopy (TEM) and zeta potential measurement. The lysozyme immobilization was verified by Fourier transform infrared (FTIR) spectroscopy. The effects of pHs and temperatures on lysozyme adsorption were investigated as well. It was revealed that CaCO3/CMC microspheres could immobilize lysozyme efficiently via electrostatic interactions and a maximum adsorption capacity of 450 mg/g was achieved at pH 9.2 and 25 °C. Moreover, it was found that the adsorption process fitted well with the Langmuir isothermal model. In addition, UV, fluorescence, and circular dichroism (CD) spectroscopic studies showed that lysozyme maintained its original secondary structure during the adsorption/desorption process. Our study therefore demonstrated that CaCO3/CMC microsphere can be used as a cost-effective and efficient support for lysozyme immobilization. - Graphical abstract: CaCO3/CMC microsphere was prepared by a facile biomimetic mineralization method and can be used as an efficient and cost-effective support for lysozyme immobilization. Highlights: ► CaCO3/CMC microspheres were prepared by the biomimetic mineralization method. ► Lysozyme was efficiently immobilized to CaCO3/CMC microspheres via adsorption. ► A maximum adsorption capacity of 450 mg/g was obtained at pH 9.2 and 25 °C. ► The original secondary structure of lysozyme was maintained upon immobilization.

  7. Microbial carbon mineralization in tropical lowland and montane forest soils of Peru

    Directory of Open Access Journals (Sweden)

    Jeanette eWhitaker

    2014-12-01

    Full Text Available Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C balance of these ecosystems by altering decomposition processes e.g. ‘positive priming effects’ that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labelled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesised that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils.

  8. Vibrational spectra of the hydrated carbonate minerals ikaite, monohydrocalcite, lansfordite and nesquehonite

    Science.gov (United States)

    Coleyshaw, Esther E.; Crump, Gregory; Griffith, William P.

    2003-08-01

    The Raman (200-4000 cm -1) and infrared (600-4000 cm -1) spectra of four rare carbonate hydrate minerals are reported. These are naturally occurring and synthetic ikaite CaCO 3 · 6H 2O, and nesquehonite MgCO 3 · 3H 2O; natural monohydrocalcite CaCO 3 · H 2O, and synthetic lansfordite MgCO 3 · 5H 2O. The spectra of synthetic ikaite partially substituted with 2H 2O and also with 13C were measured, as were those of synthetic deuteriated nesquehonite. Spectra of ikaite and lansfordite, both of which decompose at room temperatures, were measured below 0 °C. Assignments of fundamental modes are proposed.

  9. In Situ Carbon Dioxide Sequestration via Mineral Carbonation: New Insights from Lab-scale Flow-through Experiments (Invited)

    Science.gov (United States)

    Gouze, P.; Luquot, L.; Andreani, M.; Godard, M.; Peuble, S.

    2010-12-01

    Because carbonates are stable over geological time periods, in situ mineral carbonation is, in theory, a safe technique to trap CO2. It implies however the dissolution of Mg, Ca, and Fe-rich silicates. Therefore, it is mainly restricted to geological formations rich in divalent cations such as ultramafic rocks (peridotite, serpentinite), basalts and zeolite-rich sandstones. CO2 underground storage is an industrial technology that requires predictive modeling tools for assessing feasibility and risks. It means that controlling mechanisms and effective parameters (i.e. used at Darcy scale) as well as uncertainties must be identified. However, dissolution-precipitation processes involve complex coupled mechanisms, strongly controlled by the hydrodynamical and chemical variability of the system at all scales. Specifically, the upscaling from pore scale to Darcy scale is challenging, not only because of the hydrodynamical and mineralogical heterogeneities, but also because of the strong thermodynamic disequilibrium and the relatively high flow rate expected in the vicinity of the CO2 injection. Therefore, reproducing such processes at lab scale, where conditions are fully controlled, is the only way to fully investigate mass transfers, develop pertinent transport-reaction models and measure effective parameters. We present three set of lab experiments during which CO2-saturated brine is injected into (i) peridotites, (ii) olivine-rich basalts and (iii) zeolite-rich sandstones. These experiments show that mass transfers are heterogeneous at pore- and sample-scale: (i) in peridotites, Ca-magnesite and talc precipitate in low flow zones while Si-rich layer develop at olivine surface in higher flow zones, thus providing a mechanism maintaining constant permeability; (ii) in olivine/basaltic matrix, porosity increases upstream due to efficient dissolution of basaltic glass (+/- olivine); precipitation of ankerite is localized in the high porosity zone while serpentine

  10. Single-walled carbon nanotubes functionalized with sodium hyaluronate enhance bone mineralization

    Directory of Open Access Journals (Sweden)

    M.A. Sá

    2016-01-01

    Full Text Available The aim of this study was to evaluate the effects of sodium hyaluronate (HY, single-walled carbon nanotubes (SWCNTs and HY-functionalized SWCNTs (HY-SWCNTs on the behavior of primary osteoblasts, as well as to investigate the deposition of inorganic crystals on titanium surfaces coated with these biocomposites. Primary osteoblasts were obtained from the calvarial bones of male newborn Wistar rats (5 rats for each cell extraction. We assessed cell viability using the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl-2H-tetrazolium bromide assay and by double-staining with propidium iodide and Hoechst. We also assessed the formation of mineralized bone nodules by von Kossa staining, the mRNA expression of bone repair proteins, and the deposition of inorganic crystals on titanium surfaces coated with HY, SWCNTs, or HY-SWCNTs. The results showed that treatment with these biocomposites did not alter the viability of primary osteoblasts. Furthermore, deposition of mineralized bone nodules was significantly increased by cells treated with HY and HY-SWCNTs. This can be partly explained by an increase in the mRNA expression of type I and III collagen, osteocalcin, and bone morphogenetic proteins 2 and 4. Additionally, the titanium surface treated with HY-SWCNTs showed a significant increase in the deposition of inorganic crystals. Thus, our data indicate that HY, SWCNTs, and HY-SWCNTs are potentially useful for the development of new strategies for bone tissue engineering.

  11. Redistribution of soil water by a saprotrophic fungus enhances carbon mineralization.

    Science.gov (United States)

    Guhr, Alexander; Borken, Werner; Spohn, Marie; Matzner, Egbert

    2015-11-24

    The desiccation of upper soil horizons is a common phenomenon, leading to a decrease in soil microbial activity and mineralization. Recent studies have shown that fungal communities and fungal-based food webs are less sensitive and better adapted to soil desiccation than bacterial-based food webs. One reason for a better fungal adaptation to soil desiccation may be hydraulic redistribution of water by mycelia networks. Here we show that a saprotrophic fungus (Agaricus bisporus) redistributes water from moist (-0.03 MPa) into dry (-9.5 MPa) soil at about 0.3 cm ⋅ min(-1) in single hyphae, resulting in an increase in soil water potential after 72 h. The increase in soil moisture by hydraulic redistribution significantly enhanced carbon mineralization by 2,800% and enzymatic activity by 250-350% in the previously dry soil compartment within 168 h. Our results demonstrate that hydraulic redistribution can partly compensate water deficiency if water is available in other zones of the mycelia network. Hydraulic redistribution is likely one of the mechanisms behind higher drought resistance of soil fungi compared with bacteria. Moreover, hydraulic redistribution by saprotrophic fungi is an underrated pathway of water transport in soils and may lead to a transfer of water to zones of high fungal activity. PMID:26554004

  12. Effect of reactive surface area of minerals on mineralization and carbon dioxide trapping in a depleted gas reservoir

    NARCIS (Netherlands)

    Bolourinejad, P.; Shoeibi Omrani, P.; Herber, R.

    2014-01-01

    In this study, a long-term (up to 1000 years) geochemical modelling of subsurface CO2 storage was carried out on sandstone reservoirs of depleted gas fields in northeast Netherlands. It was found that mineral dissolution/precipitation has only a minor effect on reservoir porosity. In order to valida

  13. Effect of Electrochemical Treatment in Aqueous Ammonium Bicarbonate on Surface Properties of PAN-based Carbon Fibers

    Institute of Scientific and Technical Information of China (English)

    曹海琳; 黄玉东; 张志谦; 孙举涛

    2004-01-01

    The surface properties of PAN-based carbon fibers electrochemically treated in aqueous ammonium bicarbonate before and after treatment were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Dynamic Contact Angle Analysis (DCAA). The results of characterization indicated that the oxygen and nitrogen contents in carbon fiber surface were significantly increased by electrochemical treatment, and amide groups was introduced onto it, which was related with the electrolyte. The AFM photographs illustrated that the roughness of the fiber surface was also increased. The wettibality of the fibers was improved after treatment because the surface energy especially the polar part of it was increased.

  14. Conversion electron Moessbauer study of low carbon steel polarized in aqueous sulfate solution containing sulfite in low concentration

    International Nuclear Information System (INIS)

    The passivation of low carbon steel was studied in aqueous solution of 0.5 M Na2SO4+0.001 M NaHSO3 at pH=3.5 and 6.5. The found major components at pH=3.5 were: γ-FeOOH and Fe3C, and also FeSO4.H2O could be identified on the surface of the low carbon steel as a minor component. At pH=6.5, the passive film contained only amorphous iron(III)-oxide or oxyhydroxide. (orig.)

  15. Computational insights into the effect of carbon structures at the atomic level for non-aqueous sodium-oxygen batteries

    Science.gov (United States)

    Jiang, H. R.; Wu, M. C.; Zhou, X. L.; Yan, X. H.; Zhao, T. S.

    2016-09-01

    Carbon materials have been widely used to form air cathodes for non-aqueous sodium-oxygen (Nasbnd O2) batteries due to their large specific surface area, high conductivity and low cost. However, the effect of carbon structures at the atomic level remains poorly understood. In this work, a first-principles study is conducted to investigate how representative carbon structures, including graphite (0001) surface, point defects and fractured edge, influence the discharge and charge processes of non-aqueous Nasbnd O2 batteries. It is found that the single vacancy (SV) defect has the largest adsorption energy (5.81 eV) to NaO2 molecule among the structures studied, even larger than that of the NaO2 molecule on NaO2 crystal (2.81 eV). Such high adsorption energy is attributed to two factors: the dangling atoms in SV defects decrease the distance from NaO2 molecules, and the attachment through oxygen atoms increases the electrons transfer. The findings suggest that SV defects can act as the nucleation sites for NaO2 in the discharge process, and increasing the number of SV defects can facilitate the uniform formation of small-sized particles. The uniformly distributed discharge products lower the possibility for pore clogging, leading to an increased discharge capacity and improved cyclability for non-aqueous Nasbnd O2 batteries.

  16. Mineralogy and stable isotope compositions of carbonate and sulphide minerals of carbonate crusts associated with gas hydrate-forming cold vents from the NE Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Conly, A.G. [Lakehead Univ., Thunder Bay, ON (Canada). Dept. of Geology; Scott, S.D. [Toronto Univ., ON (Canada). Dept. of Geology; Riedel, M. [Natural Resources Canada, Sidney, BC (Canada). Geological Survey of Canada, Pacific Geoscience Centre

    2005-07-01

    In 2001, the ROPOS submersible sampled 21 specimens of carbonate crusts from 2 gas hydrate fields located offshore Vancouver Island on the northeast Pacific continental margin. The mineralogy and stable isotopic composition of carbonate and sulphide minerals were used to evaluate petrogenesis and the relationship to associated gas hydrate occurrences. The crusts form the upper surface of carbonate and pelagic mud mounds within the gas hydrate fields. The crusts are made up of micritic carbonate with a highly variable morphology that includes blocky, fissile, nodular and mudcemented brecciated forms. The crusts include micritic calcite and dolomite/ferroan dolomite, with up to 30 per cent detrital and authigenic silicates. The finely disseminated sulphide minerals include pyrite and trace amounts of sphalerite. Bulk-rock chemical compositions are mainly homogeneous. Any variations reflect the calcite:dolomite and carbonate:silicate ratios. The {delta}13 C values for bulk carbonate (calcite and dolomite) were presented. No definitive correlation between {delta}13 C value and carbonate mineralogy was noted, but calcite-dominant samples were found to be more depleted. The {delta}34 S values for sulphide were also presented. The carbon isotopic composition of the carbonate is associated with the balance of inorganic and organic carbon species. Bacterial sulphate reduction and/or bacterial fermentation and carbonate reduction processes responsible for the production of methane were found to control the {delta}13 C of the carbon dioxide reservoir in gas hydrate environments. It was shown that methane was the carbon source involved in bacterial sulphate reduction and that the isotopic composition of the CO{sub 2} reservoir may be controlled by fractionation during bacterial carbonate reduction. The range in sulphur isotopes correlates with the bacterial sulphate reduction under partially closed conditions, where the rate of diffusion of sulphate is less than the rate of

  17. Computational Redox Potential Predictions: Applications to Inorganic and Organic Aqueous Complexes, and Complexes Adsorbed to Mineral Surfaces

    OpenAIRE

    Krishnamoorthy Arumugam; Udo Becker

    2014-01-01

    Applications of redox processes range over a number of scientific fields. This review article summarizes the theory behind the calculation of redox potentials in solution for species such as organic compounds, inorganic complexes, actinides, battery materials, and mineral surface-bound-species. Different computational approaches to predict and determine redox potentials of electron transitions are discussed along with their respective pros and cons for the prediction of redox potentials. Subs...

  18. The effect of surface oxides on multi-walled carbon nanotube aqueous colloidal properties

    Science.gov (United States)

    Smith, Billy

    Carbonaceous nanomaterials are being produced and integrated into consumer products and specialized applications at an accelerating rate. Recently, however, concerns have increased about the environmental, health and safety risks of these nanomaterials, particularly those chemically functionalized to enhance their aqueous colloidal stability and biocompatibility. In this dissertation research, I have investigated the role that surface-oxide concentration plays in the aqueous colloidal stability of multi-walled carbon nanotubes (MWCNTs), a prominent class of engineered nanomaterials. To vary the concentration of surface oxides on the MWCNTs' surface, pristine (unmodified) tubes were treated with a wet-chemical oxidant (e.g., HNO3, H2SO4 /HNO3, KMnO4); the concentration of surface oxides imparted was measured by x-ray photoelectron spectroscopy (XPS). In conjunction with XPS, previously developed chemical derivatization techniques were used to determine the distribution of hydroxyl, carboxyl, and carbonyl functional groups present on the MWCNTs' surface. The length distribution and structural integrity of pristine and oxidized MWCNTs were characterized using atomic force microscopy and transmission electron microscopy, respectively. To examine the aqueous colloidal stability and aggregation properties of oxidized MWCNTs, sedimentation and time-resolved dynamic light scattering (TR-DLS) experiments were conducted on neat (i.e., ideal) suspensions prepared by prolonged sonication of MWCNTs in Milli-Q water. Over a range of environmentally relevant pH values (4--9) and electrolyte (NaCL, CaCl2) concentrations (0.001--1.000 M), the aggregation and colloidal properties of MWCNTs were found to agree with the basic tenants of DLVO theory, in that ( i) more highly oxidized, negatively charged MWCNTs remained stable over a wider range of solution conditions than lowly oxidized tubes, ( ii) oxidized MWCNTs adhered to the empirical Schulze-Hardy rule, and (iii) in early

  19. Use of laser spectroscopy to measure the 13C/12C and 18O/16O compositions of carbonate minerals.

    Science.gov (United States)

    Barker, Shaun L L; Dipple, Gregory M; Dong, Feng; Baer, Douglas S

    2011-03-15

    The stable carbon and oxygen isotope compositions of carbonate minerals are utilized throughout the earth and environmental sciences for various purposes. Here, we demonstrate the first application of a prototype instrument, based on off-axis integrated cavity output laser spectroscopy, to measure the carbon and oxygen isotope composition of CO(2) gas evolved from the acidification of carbonate minerals. The carbon and oxygen isotope ratios were recorded from absorption spectra of (12)C(16)O(16)O, (13)C(16)O(16)O, and (12)C(16)O(18)O in the near-infrared wavelength region. The instrument was calibrated using CaCO(3) minerals with known δ(13)C(VPDB) and δ(18)O(VSMOW) values, which had been previously calibrated by isotope ratio mass spectrometry relative to the international isotopic standards NBS 18 and NBS 19. Individual analyses are demonstrated to have internal precision (1 SE) of better than 0.15‰ for δ(13)C and 0.6‰ for δ(18)O. Analysis of four carbonate standards of known isotopic composition over 2 months, determined using the original instrumental calibration, indicates that analyses are accurate to better than 0.5‰ for both δ(13)C and δ(18)O without application of standard-sample-standard corrections. PMID:21341717

  20. An economic analysis of the Jim Bridger Power Plant carbon dioxide mineralization process

    Science.gov (United States)

    Christensen, Mikol Hans

    Concerns for rising levels of CO2 in the atmosphere have lead to a myriad of schemes to reduce emissions. Many of these are complicated, expensive, and untried. Coal-fired electrical generation accounts for about 49 percent of U.S. electricity generation. Shifting generation capacity away from coal is the goal of many, yet as this statistic shows, the U.S. has a heavy dependency on coal-fired base-load generation. What is needed is a way to retrofit existing coal fired power plants to mitigate at least some of the giga-tonnes of CO2 released annually. Carbon Capture and Storage in association with greenhouse gases are a major concern in the world today. This thesis is an outgrowth of a research partnership between the University of Wyoming and the Jim Bridger Power Plant (Rocky Mountain Power) to develop a process for capture and mineralization of flue gas carbon dioxide (CO 2) using an accelerated mineral carbonization process with fly ash particles as the absorbent. This process may have several advantages over other approaches because it is an environmentally acceptable, single step process occurring at near ambient pressures and temperatures that can compliment conventional CCS processes. In addition the use of fly ash particles as an absorbent avoids the costs of processing or engineering an absorbent. The purpose of this thesis is to evaluate the capture costs and economic feasibility of the mineralization process. Two models were used to estimate the capture costs and economic feasibility of the Jim Bridger Power Plant CO2 Mineralization Project (JBP). The first was a cost of capture model which was used to estimate CO2 capture costs and how changes in the CO2 to ash capture ratio and quantities of CO2 captured affect capture costs. The second was a financial feasibility model which considered the time value of money. This second model considered the net present value (NPV) and internal rate of return (IRR) for the process using different pricing scenarios

  1. Adsorption of cadmium ions from aqueous solution using granular activated carbon and activated clay

    Energy Technology Data Exchange (ETDEWEB)

    Wasewar, Kailas L. [Department of Chemical Engineering, Visvesvaraya National Institute of Technology (VNIT), Nagpur, Maharashtra (India); Kumar, Pradeep; Teng, Tjoon Tow [Environmental Technology Division, School of Industrial Technology, University Science of Malaysia, Minden, Penang (Malaysia); Chand, Shri; Padmini, Bina N. [Department of Chemical Engineering, Indian Institute of Technology, Roorkee (India)

    2010-07-15

    The present study was aimed at removing cadmium ions from aqueous solution through batch studies using adsorbents, such as, granular activated carbon (GAC) and activated clay (A-clay). GAC was of commercial grade where as the A-clay was prepared by acid treatment of clay with 1 mol/L of H{sub 2}SO{sub 4}. Bulk densities of A-clay and GAC were 1132 and 599 kg/m{sup 3}, respectively. The surface areas were 358 m{sup 2}/g for GAC and 90 m{sup 2}/g for A-clay. The adsorption studies were carried out to optimize the process parameters, such as, pH, adsorbent dosage, and contact time. The results obtained were analyzed for kinetics and adsorption isotherm studies. The pH value was optimized at pH 6 giving maximum Cd removal of 84 and 75.2% with GAC and A-clay, respectively. The adsorbent dosage was optimized and was found to be 5 g/L for GAC and 10 g/L for A-clay. Batch adsorption studies were carried out with initial adsorbate (Cd) concentration of 100 mg/L and adsorbent dosage of 10 g/L at pH 6. The optimum contact time was found to be 5 h for both the adsorbents. Kinetic studies showed Cd removal a pseudo second order process. The isotherm studies revealed Langmuir isotherm to better fit the data than Freundlich isotherm. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. Adsorption of chlorophenols from aqueous solutions by pristine and surface functionalized single-walled carbon nanotubes.

    Science.gov (United States)

    Ding, Han; Li, Xin; Wang, Jun; Zhang, Xiaojian; Chen, Chao

    2016-05-01

    The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes (SWCNTs) has been investigated. Pseudo-first order and pseudo-second order models were used to describe the kinetic data. All adsorption isotherms were well fitted with Langmuir, Freundlich and Polanyi-Manes models, due to surface adsorption dominating the adsorption process. The close linear relationship between logKow and logKd suggested that hydrophobicity played an important role in the adsorption. The SWCNTs' adsorption capacity for chlorophenols was weakened by addition of oxygen-containing functional groups on the surface, due to the loss of specific surface area, the increase of hydrophilicity and the reduction of π-π interaction. The best adsorption capacity of pristine SWCNTs, SWCNT-OH and SWCNT-COOH for six chlorophenols varied from 19 to 84mg/g, from 19 to 65mg/g and from 17 to 65mg/g, respectively. The effect of pH on the adsorption of 2,6-dichlorophenol (2,6-DCP), was also studied. When pH is over the pKa of 2,6-dichlorophenol (2,6-DCP), its removal dropped sharply. When ionic strength increased (NaCl or KCl concentration from 0 to 0.02mmol/L), the adsorption capacity of 2,6-DCP on pristine SWCNTs decreased slightly. The comparison of chlorophenols adsorption by SWCNTs, MWCNTs and PAC was made, indicating that the adsorption rate of CNTs was much faster than that of PAC. The results provide useful information about the feasibility of SWCNTs as an adsorbent to remove chlorophenols from aqueous solutions. PMID:27155424

  3. Multiwalled Carbon Nanotube/Cellulose Composite: From Aqueous Dispersions to Pickering Emulsions.

    Science.gov (United States)

    Avendano, Carlos; Brun, Nicolas; Fontaine, Olivier; In, Martin; Mehdi, Ahmad; Stocco, Antonio; Vioux, André

    2016-04-26

    A mild and simple way to prepare stable aqueous colloidal suspensions of composite particles made of a cellulosic material (Sigmacell cellulose) and multiwalled carbon nanotubes (MWCNTs) is reported. These suspensions can be dried and redispersed in water at pH 10.5. Starting with rather crude initial materials, commercial Sigmacell cellulose and MWCNTs, a significant fraction of composite dispersed in water could be obtained. The solid composites and their colloidal suspensions were characterized by electronic microscopy, thermal analyses, FTIR and Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and light scattering. The composite particles consist of tenuous aggregates of CNTs and cellulose, several hundred nanometers large, and are composed of 55 wt % cellulose and 45 wt % CNTs. Such particles were shown to stabilize cyclohexane-in-water emulsions. The adsorption and the elasticity of the layer they form at interface were characterized by the pendant drop method. The stability of the oil-in-water emulsions was attributed to the formation of an elastic network of composite particles at interface. Cyclohexane droplet diameters could be tuned from 20 to 100 μm by adjusting the concentration of composite particles. This behavior was attributed to the limited coalescence phenomenon, just as expected for Pickering emulsions. Interestingly, cyclohexane droplets were stable over time and sustained pH modifications over a wide range, although acidic pH induced accelerated creaming. This study points out the possibility of combining crude cellulose and MWCNTs through a simple process to obtain colloidal systems of interest for the design of functional conductive materials. PMID:27052957

  4. Aqueous leaching of organic acids and dissolved organic carbon from various biochars prepared at different temperatures.

    Science.gov (United States)

    Liu, Peng; Ptacek, Carol J; Blowes, David W; Berti, William R; Landis, Richard C

    2015-03-01

    Biochar has been used as a soil amendment, as a water treatment material, and for carbon (C) sequestration. Thirty-six biochars, produced from wood, agricultural residue, and manure feedstocks at different temperatures, were evaluated for the aqueous leaching of different forms of soluble C. The release of inorganic C (alkalinity), organic acids (OAs), and total dissolved organic C (DOC) was highly variable and dependent on the feedstock and pyrolysis temperature. The pH and alkalinity increased for the majority of samples. Higher pH values were associated with high-temperature (high-T) (600 and 700°C) biochars. Statistically significant differences in alkalinity were not observed between low-temperature (low-T) (300°C) and high-T biochars, whereas alkalinity released from wood-based biochar was significantly lower than from others. Concentrations of OAs and DOC released from low-T biochars were greater than from high-T biochars. The C in the OAs represented 1 to 60% of the total DOC released, indicating the presence of other DOC forms. The C released as DOC represented up to 3% (majority biochar. Scanning electron microscopy with energy dispersive X-ray spectroscopy showed the high-T biochars had a greater proportion of micropores. Fourier transform infrared spectroscopy showed that hydroxyl, aliphatic, and quinone were the predominant functional groups of all biochars and that the abundance of other functional groups was dependent on the feedstock. The release of DOC, especially bioavailable forms such as OAs, may promote growth of organisms and heavy metal complexation and diminish the potential effectiveness of various biochars for C sequestration. PMID:26023986

  5. Carbon Mineralization and Nitrogen Transformation During a Long Term Permafrost Incubation

    Science.gov (United States)

    Salmon, V. G.; Mack, M. C.; Schuur, E. A. G.

    2014-12-01

    As the limiting nutrient in warming high latitude ecosystems, nitrogen (N) is expected to play a key role in determining the future balance between permafrost carbon (C) losses and increased C sequestration by plants. During decomposition, nitrogen previously locked in soil organic matter is released into the soil solution in the form of dissolved organic molecules following depolymerization by extracellular enzymes. These dissolved organic forms of N can be consumed by the soil microbial community and incorporated in their biomass or mineralized if they are in excess of microbial demand. Once mineralized and released into the soil solutions, N can be lost from the soil system via denitrification. In well drained, low N tussock tundra, however, this pathway is unlikely. Dissolved inorganic N (DIN) and dissolved organic N (DON) are both biologically available to arctic plants. Understanding how the size of these pools changes with depth and continuing decomposition is therefore crucial to projecting the C balance of high latitude systems in a warmer future. N transformations associated with decomposition may differ greatly in surface soils, where a large labile C pool is present and soil has a high C:N ratio, versus deep soils that have a relatively small labile C pool and a lower C:N ratio. In this experiment, the relationship between N availability and C release from permafrost soils was addressed with a 225 day soil incubation performed at 15°C. Seven soil cores were collected from undisturbed, well drained tussock tundra and were partitioned into ten centimeter depth intervals to a depth of 80 cm. Carbon dioxide (CO2) fluxes were measured throughout the incubation period and were used to assess cumulative carbon losses and determine the size of the labile C pool. Destructive harvests at days 16,34,55,83, 143 and 225 were performed and pools of plant available DON and DIN were measured using 2M KCl extractions. At day 225 the microbial biomass N pool was also

  6. The dynamic controls on carbonate mineral saturation states and ocean acidification in a glacially dominated estuary

    Science.gov (United States)

    Reisdorph, Stacey C.; Mathis, Jeremy T.

    2014-05-01

    Recently, a number of studies have shown that the intrusion of anthropogenic carbon dioxide (CO2) into the ocean has created an acidification effect leading to the reduction in carbonate mineral saturation states (Ω). However, the uptake of atmospheric CO2 is not the only climate-induced phenomenon that leads to a reduction of Ω in marine environments. Over the past ∼250 years, Glacier Bay, AK (GLBA) has experienced rapid deglaciation leading to an increase in the amount of freshwater entering the marine ecosystem. This excess freshwater discharge is low in total alkalinity and reduces the buffering capacity of surface waters and enhances the vulnerability of the estuary to further reductions in pH. The corresponding reduction in Ω may cause these waters to become corrosive to shell-building organisms. To better understand these processes, we collected monthly samples within GLBA that show the variability in Ω throughout the water column. Low Ω values were well correlated with the timing of maximum glacial discharge events and most prominent within the two regions where tidewater glacial discharge was highest. The saturation state with respect to aragonite reached a minimum of 0.40 at the surface during the summer of 2011 before rebounding to a maximum value of 3.26 in the spring of 2012. Aragonite was undersaturated at the surface throughout the entire bay during fall months (Sept. and Oct.). Here, we present results from a year-long study designed to constrain the effects of glacial freshwater discharge on the marine carbonate system and discern the primary controls on Ω in this pristine estuarine environment.

  7. Corrosion inhibition behavior of propyl phosphonic acid–Zn2+ system for carbon steel in aqueous solution

    International Nuclear Information System (INIS)

    The effectiveness of propyl phosphonic acid (PPA) as a corrosion inhibitor in association with a bivalent cation like Zn2+ has been studied. An eco-friendly inhibitor in controlling corrosion of carbon steel in neutral aqueous medium in the absence and presence of Zn2+ has been evaluated by gravimetric method. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. Potentiodynamic polarization studies showed that the inhibitor is a mixed inhibitor. X-ray photoelectron spectroscopic analysis (XPS) of the protective film exhibited the presence of the elements viz., iron, phosphorus, oxygen, carbon and zinc. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(II)/(III)–Zn(II)–PPA] complex. Further, the surface analysis techniques viz., FT-IR, AFM and SEM studies confirm the formation of an adsorbed protective film on the carbon steel surface. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  8. Preparation and characterization of carbon supported nano-nickel and its sorption behavior for zinc from aqueous solutions

    International Nuclear Information System (INIS)

    Nickel deposited on carbon has been used as adsorbent to recover Zn (II) from aqueous system. The adsorbent was synthesized by depositing nickel nitrate on carbon under inert conditions and decomposing it to nickel by raising the temperature, washing and vacuum drying. Various techniques including XRD, FTIR, and SEM were employed for its characterization. FTIR showed that the nickel deposition enhanced the carbon functionalization due to presence of OH, C=O and C-O groups. Average crystallite size of about 9 nm was determined from XRD. Nickel deposition resulted in further division particles as indicated from the morphological study. Zn (II) was subjected to adsorption on the synthesized adsorbent. It was observed that the rate of adsorption increased significantly on the nickel deposited carbon than the carbon alone. Morris-Weber, Lagrangian and Reichenberg models were applied to find out the type and rate of adsorption employing first and second order rate equations. The adsorption data were applied to Langmuir, Freundlich and D-R isotherms and values of isotherm constants were calculated and were higher for Ni/C than carbon alone. The mean free energy of zinc sorption on carbon and Ni/C are 16.67 and 18.26 kJmol/sup -1/ which shows chemisorption. Thermodynamic studies were done to find out the effect of temperature on sorption. Positive values of del H and negative values of del G show endothermic and spontaneous type of sorption. (author)

  9. In vitro formation of Ca-oxalates and the mineral glushinskite by fungal interaction with carbonate substrates and seawater

    Directory of Open Access Journals (Sweden)

    K. Kolo

    2005-01-01

    Full Text Available This study investigates the in vitro formation of Ca-oxalates and glushinskite through fungal interaction with carbonate substrates and seawater as a process of biologically induced metal recycling and neo-mineral formation. The study also emphasizes the role of the substrates as metal donors. In the first experiment, thin sections prepared from dolomitic rock samples of Terwagne Formation (Carboniferous, Viséan, northern France served as substrates. The thin sections placed in Petri dishes were exposed to fungi grown from naturally existing airborne spores. In the second experiment, fungal growth and mineral formation was monitored using only standard seawater (SSW as a substrate. Fungal growth media consisted of a high protein/carbohydrates and sugar diet with demineralized water for irrigation. Fungal growth process reached completion under uncontrolled laboratory conditions. The newly formed minerals and textural changes caused by fungal attack on the carbonate substrates were investigated using light and scanning electron microscopy (SEM-EDX, x-ray diffraction (XRD and Raman spectroscopy. The fungal interaction and attack on the dolomitic and seawater substrates resulted in the formation of Ca-oxalates (weddellite CaC2O4·2(H2O, whewellite (CaC2O4·(H2O and glushinskite MgC2O4·2(H2O associated with the destruction of the original hard substrates and their replacement by the new minerals. Both of Ca and Mg were mobilized from the experimental substrates by fungi. This metal mobilization involved a recycling of substrate metals into newly formed minerals. The biochemical and diagenetic results of the interaction strongly marked the attacked substrates with a biological fingerprint. Such fingerprints are biomarkers of primitive life. The formation of glushinskite is of specific importance that is related, besides its importance as a biomineral bearing a recycled Mg, to the possibility of its transformation through diagenetic pathway into an

  10. Supercritical carbon dioxide extractions of agricultural chemicals from aqueous solutions; Chorinkai nisankatanso ni yoru suiyoeki karano noyaku no chushitsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, T.; Sato, Y.; Takahashi, N.; Kato, Y. [National Inst. for Resources and Environment, Tsukuba (Japan). Advanced Water Treatment Division

    1999-12-10

    Examination was made on the supercritical carbon dioxide extraction of agricultural chemicals from aqueous solutions. In the case of the semi batch extraction blowing supercritical carbon dioxide into the aqueous solutions at a concentration of 5 mg L{sup -1}, the dependencies of the removal ratios of four kinds of agricultural chemicals on temperature and pressure were shown in different patterns depending on the agricultural chemicals. For simazin (CAT), no unusual phenomena were observed. On the other hand, isoprothiolane (IPT) exhibited unusual phenomena. That is, the removal ratios decreased, as the pressure increased above 100 kg cm{sup -2} at temperatures of 45 degree C and 50 degree C. A similar phenomenon was observed for fenitrothion (MEP) or napropamide (NPP). Complicate pattern was shown for MEP. The removal ratios at pressures of 80 kg cm{sup -2} and 90 kg cm{sup -2} had maxima at 40 degree C and 45 degree C, respectively. These phenomena were discussed in terms of equilibrium and mass transfer. It was referred to that consideration should be given to such phenomena when the extraction technique is used for analysis. The order of the easiness of the separation of agricultural chemical from aqueous solution (that was estimated by the removal ratio at temperature of 35 degree C and pressure of 100 kg cm{sup -2}) was IPT>NPP>MEP>CAT. Correlation was seen between the removal ratio and the solubility of agricultural chemical in water, and in hexane or the melting point. (author)

  11. Hybrid capacitors utilizing halogen-based redox reactions at interface between carbon positive electrode and aqueous electrolytes

    Science.gov (United States)

    Yamazaki, Shigeaki; Ito, Tatsuya; Murakumo, Yuka; Naitou, Masashi; Shimooka, Toshiharu; Yamagata, Masaki; Ishikawa, Masashi

    2016-09-01

    We propose novel hybrid capacitors (HCs) with electrolyte-involved redox reactions of bromide or iodide species by pretreatment of an activated carbon positive electrode. The treatment is simple; impregnation of pores at an activated carbon fiber cloth (ACFC) as a positive electrode with bromine- or iodine-containing water before cell assembly. The treated positive electrode is applied to a HC cell with a non-treated negative electrode of ACFC and its electrochemical performance is investigated by galvanostatic cycling and leakage current tests. Few studies on such "electrolytic" charge storage systems have provided acceptable capacitor performance because of inevitable self-discharge caused by diffusion of charged species form an electrode to the other one through an electrolyte. Nevertheless, our electrolyte-redox-based HCs show excellent performance without undesirable diffusion of charged species. Moreover, the present HC utilizing a bromide redox system fulfills a practical cell voltage of 1.8 V in spite of an aqueous electrolyte system. This high voltage provides excellent energy density, which is 5 times higher than that in a conventional aqueous electric double-layer capacitor (EDLC), and 1.2 times higher even than that in a 2.7 V-class non-aqueous EDLC, while keeping high charge-discharge rate capability.

  12. The accumulation of organic carbon in mineral soils by afforestation of abandoned farmland.

    Directory of Open Access Journals (Sweden)

    Xiaorong Wei

    Full Text Available The afforestation of abandoned farmland significantly influences soil organic carbon (OC. However, the dynamics between OC inputs after afforestation and the original OC are not well understood. To learn more about soil OC dynamics after afforestation of farmland, we measured the soil OC content in paired forest and farmland plots in Shaanxi Province, China. The forest plots had been established on farmland 18, 24, 48, 100, and 200 yr previously. The natural (13C abundance of soil organic matter was also analyzed to distinguish between crop- and forest-derived C in the afforested soils. We observed a nonlinear accumulation of total OC in the 0-80 cm depth of the mineral soil across time. Total soil OC accumulated more rapidly under forest stands aged 18 to 48 yr than under forest stands aged 100 or 200 yrs. The rate of OC accumulation was also greater in the 0-10 cm depth than in the 10-80 cm depth. Forest-derived OC in afforested soils also accumulated nonlinearly across time, with the greatest increase in the 0-20 cm depth. Forest-derived OC in afforest soils accounted for 52-86% of the total OC in the 0-10 cm depth, 36-61% of the total OC in the 10-20 cm depth, and 11-50% of the total OC in the 20-80 cm depth. Crop-derived OC concentrations in the 0-20 cm depth decreased slightly after afforestation, but there was no change in crop-derived OC concentrations in the 20-80 cm depth. The results of our study support the claim that afforestation of farmland can sequester atmospheric CO(2 by increasing soil OC stocks. Changes in the OC stocks of mineral soils after afforestation appear to be influenced mainly by the input of forest-derived C rather than by the loss of original OC.

  13. The carbon isotope ratios and contents of mineral elements in leaves of Chinese medicinal plants

    International Nuclear Information System (INIS)

    Leaf carbon isotope ratios and 13 kinds of mineral elements were measured on 36 species of common Chinese medicinal plants in a subtropical monsoon forest of Ding Hu Shan in Guangdong Province. The .delta.13C value were from -26.4 to -32.6%, indicating that all of the species belonged the photosynthetic C3 types. The relative lower value of δ13C was observed in the life form of shrubs. The contents of 7 elements (N, P, K, Ca, Na Mg, Si) were dependent upon the species, life form, medicinal function and medicinal part. Herb type medicine and the used medicinal part of leaves or whole plant showed higher levels of above elements than the others. Among the nine groups with different medicinal functions, it was found that more nitrogen was in the leaves of medicinal plants for hemophthisis, hypertension and stomachic troubles, more phosphorus and potassium were in the leaves for cancer and snake bite medicines, but more calcium and magnesium were in the leaves for curing rheumatics. Ferric, aluminium and manganese were the main composition of microelements in leaves. There were higher content of ferric in leaves for hemophthisis medicine, higher zinc in leaves for cold and hypertension medicine, and higher Cup in leaves of stomachic medicine. It was suggested that the pattern of mineral elements in leaves of Chinese medicinal plants reflected the different properties of absorption and accumulation. Some additional effect due to the high content of certain element might be associated with the main function of that medicine

  14. Energetic changes in the surface of activated carbons and relationship with Ni(II) adsorption from aqueous solution

    Science.gov (United States)

    Rodríguez-Estupiñan, Paola; Giraldo, Liliana; Moreno-Piraján, Juan Carlos

    2013-12-01

    This study investigated Ni(II) ion adsorption from aqueous solution on activated carbons obtained by chemically modifying the surface with the oxidizing agents nitric acid and hydrogen peroxide (CAGoxP and CAGoxN, respectively). The activated carbons were characterized by total acidity and basicity, pH at the point of charge zero determination and IR spectroscopy. Textural parameters such as the BET area and pore volumes were evaluated by gas adsorption. The BET area of the materials was between 816 and 876 m2 g-1. Additionally, the immersion enthalpies of the activated carbons in water and benzene were determined. The experimental results on adsorption in solution were adjusted to the Langmuir and Freundlich models, obtaining values for the monolayer capacity between 29.68 and 50.97 mg g-1, which indicates that the adsorption capacity depends largely on solid surface chemistry.

  15. Polymorph selection and nanocrystallite rearrangement of calcium carbonate in carboxymethyl chitosan aqueous solution: Thermodynamic and kinetic analysis

    International Nuclear Information System (INIS)

    In this article, the polymorph selection of calcium carbonate has been successfully achieved in water-soluble carboxymethyl chitosan aqueous solution at different temperatures (25-95 oC). Vaterite is formed in carboxymethyl chitosan solution 25 oC accompanied with trace of calcite, whereas pure aragonite is obtained at 95 oC. Scanning electron microscopy and transmission electron microscopy analyses show that the products are formed from the recrystallization of nanometer crystallites. Thermodynamic and kinetic analyses reveal that the polymorph of calcium carbonate is controlled and selected by kinetics in various temperatures. As a heterogeneous nucleator and stabilizing agent, carboxymethyl chitosan changes the nucleation and growth of calcium carbonate from thermodynamic into kinetic control. Under kinetic limitation, the reaction rate of aragonite increases along with the elevating of temperature and surpasses the rate of vaterite above 327 K.

  16. Polymorph selection and nanocrystallite rearrangement of calcium carbonate in carboxymethyl chitosan aqueous solution: Thermodynamic and kinetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Donghui [Key Lab For Special Functional Materials Ministry of Education, Henan University, Kaifeng 475004 (China); Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050 (China); Li, Fang; Ruan, Qichao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050 (China); Zhang, Shengmao [Key Lab For Special Functional Materials Ministry of Education, Henan University, Kaifeng 475004 (China); Zhang, Linlin; Xu, Fangfang [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050 (China)

    2010-01-15

    In this article, the polymorph selection of calcium carbonate has been successfully achieved in water-soluble carboxymethyl chitosan aqueous solution at different temperatures (25-95 {sup o}C). Vaterite is formed in carboxymethyl chitosan solution 25 {sup o}C accompanied with trace of calcite, whereas pure aragonite is obtained at 95 {sup o}C. Scanning electron microscopy and transmission electron microscopy analyses show that the products are formed from the recrystallization of nanometer crystallites. Thermodynamic and kinetic analyses reveal that the polymorph of calcium carbonate is controlled and selected by kinetics in various temperatures. As a heterogeneous nucleator and stabilizing agent, carboxymethyl chitosan changes the nucleation and growth of calcium carbonate from thermodynamic into kinetic control. Under kinetic limitation, the reaction rate of aragonite increases along with the elevating of temperature and surpasses the rate of vaterite above 327 K.

  17. Adsorption of Cd(II and Pb(II Ions from Aqueous Solution byActivated Carbon

    Directory of Open Access Journals (Sweden)

    Hayder Mohammed Abdul-Hameed

    2009-01-01

    Full Text Available Heavy metal consider as major environmental pollutants. Many of industrial wastewater effluents contain a wide range of these heavy metals. The adsorption of Cd2+ and Pb2+ metal ions from aqueous solution by activated carbon was studied. The results showed that maximum adsorption capacity occurred at 486.9×10-3 mg/kg for Pb2+ ion and 548.8×10-3 mg/kg for Cd2+ ion. The adsorption in a mixture of the metal ions had a balancing effect on the adsorption capacity of the activated carbon. The adsorption capacity of each metal ion was affected by the presence of other metal ions rather than its presence individually. The study showed the presence of other heavy metals attribute to the reduction in the activated carbon capacity, and the adsorption process was found to obeys the Freundlich isotherm for both ions.

  18. Preparation and characterization of porous carbon from expanded graphite for high energy density supercapacitor in aqueous electrolyte

    Science.gov (United States)

    Barzegar, Farshad; Bello, Abdulhakeem; Momodu, Damilola; Madito, Moshawe Jack; Dangbegnon, Julien; Manyala, Ncholu

    2016-03-01

    In this work, we present the synthesis of low cost carbon nanosheets derived from expanded graphite dispersed in Polyvinylpyrrolidone, subsequently activated in KOH and finally carbonized in Ar/H2 atmosphere. Interconnected sheet-like structure with low concentration of oxygen (9.0 at.%) and a specific surface area of 457 m2 g-1 was obtained. The electrochemical characterization of the carbon material as supercapacitor electrode in a 2-electrode configuration shows high specific capacitance of 337 F g-1 at a current density of 0.5 A g-1 as well as high energy density of 37.9 Wh kg-1 at a power density of 450 W kg-1. This electrical double layer capacitor electrode also exhibits excellent stability after floating test for 120 h in 6 M KOH aqueous electrolyte. These results suggest that this activated expanded graphite (AEG) material has great potential for high performance electrode in energy storage applications.

  19. Interactions Between Mineral Surfaces, Substrates, Enzymes, and Microbes Result in Hysteretic Temperature Sensitivities and Microbial Carbon Use Efficiencies and Weaker Predicted Carbon-Climate Feedbacks

    Science.gov (United States)

    Riley, W. J.; Tang, J.

    2014-12-01

    We hypothesize that the large observed variability in decomposition temperature sensitivity and carbon use efficiency arises from interactions between temperature, microbial biogeochemistry, and mineral surface sorptive reactions. To test this hypothesis, we developed a numerical model that integrates the Dynamic Energy Budget concept for microbial physiology, microbial trait-based community structure and competition, process-specific thermodynamically ­­based temperature sensitivity, a non-linear mineral sorption isotherm, and enzyme dynamics. We show, because mineral surfaces interact with substrates, enzymes, and microbes, both temperature sensitivity and microbial carbon use efficiency are hysteretic and highly variable. Further, by mimicking the traditional approach to interpreting soil incubation observations, we demonstrate that the conventional labile and recalcitrant substrate characterization for temperature sensitivity is flawed. In a 4 K temperature perturbation experiment, our fully dynamic model predicted more variable but weaker carbon-climate feedbacks than did the static temperature sensitivity and carbon use efficiency model when forced with yearly, daily, and hourly variable temperatures. These results imply that current earth system models likely over-estimate the response of soil carbon stocks to global warming.

  20. Dissolved organic carbon and nitrogen mineralization strongly affect co2 emissions following lime application to acidic soil

    International Nuclear Information System (INIS)

    Emission of greenhouse gases from agricultural soils has main contribution to the climatic change and global warming. Dynamics of dissolved organic carbon (DOC) and nitrogen mineralization can affect CO/sub 2/ emission from soils. Influence of DOC and nitrogen mineralization on CO/sub 2/ emissions following lime application to acidic soil was investigated in current study. Laboratory experiment was conducted under aerobic conditions with 25% moisture contents (66% water-filled pore space) at 25 degree C in the dark conditions. Different treatments of lime were applied to acidic soil as follows: CK (control), L (low rate of lime: 0.2g lime / 100 g soil) and H (high rate of lime: 0.5g lime /100g soil). CO/sub 2/ emissions were measured by gas chromatography and dissolved organic carbon, NH4 +-N, NO/sub 3/ --N and soil pH were measured during incubation study. Addition of lime to acidic soil significantly increased the concentration of DOC and N mineralization rate. Higher concentrations of DOC and N mineralization, consequently, increased the CO/sub 2/ emissions from lime treated soils. Cumulative CO/sub 2/ emission was 75% and 71% higher from L and H treatments as compared to CK. The results of current study suggest that DOC and N mineralization are critical in controlling gaseous emissions of CO/sub 2/ from acidic soils following lime application. (author)

  1. Defect effect on tribological behavior of diamond-like carbon films deposited with hydrogen diluted benzene gas in aqueous environment

    Science.gov (United States)

    Yi, Jin Woo; Park, Se Jun; Moon, Myoung-Woon; Lee, Kwang-Ryeol; Kim, Seock-Sam

    2009-05-01

    This study examined the friction and wear behavior of diamond-like carbon (DLC) films deposited from a radio frequency glow discharge using a hydrogen diluted benzene gas mixture. The DLC films were deposited on Si (1 0 0) and polished stainless steel substrates by radio frequency plasma-assisted chemical vapor deposition (r.f.-PACVD) at hydrogen to benzene ratios, or the hydrogen dilution ratio, ranging from 0 to 2.0. The wear test was carried out in both ambient and aqueous environments using a homemade ball-on-disk type wear rig. The stability of the DLC coating in an aqueous environment was improved by diluting the benzene precursor gas with hydrogen, suggesting that hydrogen dilution during the deposition of DLC films suppressed the initiation of defects in the film and improved the adhesion of the coating to the interface.

  2. Effective removal of tetracycline from aqueous solution using activated carbon prepared from tomato (Lycopersicon esculentum Mill.) industrial processing waste.

    Science.gov (United States)

    Sayğılı, Hasan; Güzel, Fuat

    2016-09-01

    Activated carbon (TAC) prepared under optimized conditions with ZnCl2 activation from a new precursor; tomato industrial processing waste (TW), was applied as an adsorbent to remove tetracycline (TC) from aqueous solution. The factors (TAC dosage, initial TC concentration, contact time, ionic strength and solution temperature) affecting the adsorption process were examined at natural pH (5.7) of TAC-TC system in aqueous solution. Kinetic data was found to be best complied by the pseudo-second order model. The isotherm analysis indicated that the equilibrium data could be represented by the Langmuir model. The maximum adsorption capacity was identified as 500.0mgg(-1) at 308K. PMID:27177317

  3. Activated carbons from potato peels: The role of activation agent and carbonization temperature of biomass on their use as sorbents for bisphenol A uptake from aqueous solutions

    Science.gov (United States)

    Arampatzidou, An; Deliyanni, Eleni A.

    2015-04-01

    Activated carbons prepared from potato peels, a solid waste by product, and activated with different activating chemicals, have been studied for the adsorption of an endocrine disruptor (Bisphenol-A) from aqueous solutions. The potato peels biomass was activated with phosphoric acid, KOH and ZnCl2. The different activating chemicals were tested in order the better activation agent to be found. The carbons were carbonized by pyrolysis, in one step procedure, at three different temperatures in order the role of the temperature of carbonization to be pointed out. The porous texture and the surface chemistry of the prepared activated carbons were characterized by Nitrogen adsorption (BET), Scanning Electron Microscope (SEM), thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FTIR). Batch experiments were performed to investigate the effect of pH, the adsorbent dose, the initial bisphenol A concentration and temperature. Equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherms. The thermodynamic parameters such as the change of enthalpy (ΔH0), entropy (ΔS0) and Gibb's free energy (ΔG0) of adsorption systems were also evaluated. The adsorption capacity calculated from the Langmuir isotherm was found to be 450 mg g-1 at an initial pH 3 at 25 °C for the phosphoric acid activated carbon, that make the activated carbon a promising adsorbent material.

  4. Tufa in Northern England: depositional facies, carbonate mineral fabrics, and role of biomineralization

    Science.gov (United States)

    Manzo, E.; Mawson, M.; Perri, E.; Tucker, M. E.

    2009-04-01

    soil hereabouts, and are gradually being washed down slope. Pisoids vary in size and shape, ranging from rods to sub-spherical forms, up to several cm long or a cm or more in diameter. The external surface is a smooth dull surface of a pale grey-buff colour; the nucleus may be a plant fragment, tufa intraclast or rock fragment. Microfacies Teesdale tufa is characterized by three microfacies all contributing to a basic stromatolitic or laminated microfabric: dendrolite, dense micrite and palisades of sparite. Laminae consist of an irregular alternation of the three microfacies, which vary in abundance within the main depositional facies. Dendrolitic layers are characterized of mineralized, upward-branching cyanobacterial filaments, forming bush-like fans. Coarse sparitic layers consist of palisades of bladed calcite spar characterized by rhombohedral terminations. Micritic layers consist of dark-brown dense laminae with some clotted fabric, composed of dark micritic crystals. In thin-section molds of moss stems are often preserved by a sparitic layer that formed a coating before decay of the moss organic tissues. Cavities are abundant in moss tufa and crusts. They are often empty or in some case filled by detrital particles. Pisoids under the microscope show a cortex characterized by a concentric structure consisting mainly dense micritic layers alternating with sporadic sparitic and/or dendrolitic layers. Calcified cyanobacterial filaments or their molds are very evident in the dendrolitic laminae, but also occur in the other microfacies, being incorporated in both the sparite macro-crystals and the micritic layers. Nanofacies of minerals The mineral composition of the autochthonous carbonate forming tufa is calcite with a few mole% Mg. Sub-hedral crystals of calcite, several tens of microns in size, form sparite crystals. Sub-polygonal micro-crystals and elongate fibres a few microns in size compose dense micrite and calcified filaments. Under extra-high SEM

  5. Separation of Co2+ present in aqueous solution on calcium carbonate

    International Nuclear Information System (INIS)

    The CaCO3 was synthesized by precipitation method and characterized using SEM, EDS, TGA and IR. It was studied the adsorption behavior of Co2+ present in aqueous solution on the synthesized material by experiments batch type at room temperature. Was found that removal of cobalt ions was greater than 40% indicating that this material can be used to remove Co2+ present in aqueous solution. (Author)

  6. Synthesis and utilization of a novel carbon nanotubes supported nanocables for the adsorption of dyes from aqueous solutions

    Science.gov (United States)

    Liu, Wei; Jiang, Xinyu; Chen, Xiaoqing

    2015-09-01

    Using multiwalled carbon nanotubes(MWCNTs) as mechanical support and glucose as carbon resource, a hydrothermal carbonization route was designed for the synthesis of MWCNTs@carbon nanocables with tunable diameter and length. MWCNTs are firstly used as templates for the formation of carbon-rich composite nanocables, and the diameter of the nanocables could be tailored through adjusting the hydrothermal time or the ratio of MWCNTs and glucose. Owing to abundant superficial oxygen-containing functional groups, porous surface and remarkable reactivity, the as-synthesized nanocables are capable of efficiently adsorbing cationic dye methylene blue (MB) and crystal violet (CV). Furthermore, the optimum adsorption conditions, kinetics, adsorption isotherms and adsorption thermodynamics of dyes were studied systematically. Additionally, the maximum adsorption capacities calculated from data analysis (298.5 mg/g for MB and 228.3 mg/g for CV) are significant higher than those of raw MWCNTs and some other adsorbents reported previously, which provides strong evidence for using MWCNTs@carbon nanocables as adsorbent to remove dyes from aqueous solutions.

  7. [Seasonal dynamics of soil organic carbon mineralization for two forest types in Xiaoxing'an Mountains, China].

    Science.gov (United States)

    Gao, Fei; Lin, Wei; Cui, Xiao-yang

    2016-01-01

    To investigate the seasonal dynamics of soil organic carbon (SOC) mineralization in Xiaoxing'an Mountain, we incubated soil samples collected from virgin Korean pine forest and broad-leaved secondary forest in different seasons in the laboratory and measured the SOC mineralization rate and cumulative SOC mineralization (Cm). We employed simultaneous reaction model to describe C mineralization kinetics and estimated SOC mineralization parameters including soil easily mineralizable C (C1), potentially mineralizable C (C₀). We also analyzed the relations between Cm, C₁and their influencing factors. Results showed that the incubated SOC mineralization rate and Cm for 0-5 cm soil layer decreased from early spring to late autumn, while for 5-10 cm soil layer the seasonal variation was not statistically significant for both forest types. The C₁ in 0-5 and 5-10 cm soil layers varied from 42.92-92.18 and 19.23-32.95 mg kg⁻¹, respectively, while the C₀ in 0-5 and 5-10 cm soil layers varied from 863.92-3957.15 and 434.15-865.79 mg · kg⁻¹, respec- tively. Both C₁ and C₀ decreased from early spring to late autumn. The proportions of C₀ in SOC for two forest types were 0.74%-2.78% and 1.11%-1.84% in 0-5 and 5-10 cm soil layers, respectively, and decreased from early spring to late autumn, indicating that SOC tended to become more stable as a whole from spring to autumn. The Cm and C₀ were significantly positively correlated to in situ soil water content and hot water-extractable carbohydrate content, but were not correlated to in situ soil temperature and cool water-extractable carbohydrate content. We concluded that soil labile organic carbon, soil physical and chemical properties contributed to the seasonal dynamics of SOC mineralization in the forests. PMID:27228587

  8. Development of a technology for obtaining flotation reagent oxane-3 for carbon mineral raw materials of Kazakhstan

    Directory of Open Access Journals (Sweden)

    Sergey Kalugin

    2014-12-01

    Full Text Available The paper represents the results of development of a technology for obtaining oxane-3 and its application for enrichment of carbon mineral raw materials. Studies on enrichment of a shungite rock showed that the increase of a pulp temperature to 30°C significantly improves the characteristics and rate of the flotation process. Measured indicators of a shungite rock enrichment using Flotol B were lower in comparison with an enrichment by oxane-3. For schungite mineral, it was established that the obtained heterocyclic compound can replace existing industrial flotation reagents in enrichment processes.

  9. Substrate quality alters microbial mineralization of added substrate and soil organic carbon

    Science.gov (United States)

    Jagadamma, S.; Mayes, M. A.; Steinweg, J. M.; Schaeffer, S. M.

    2014-03-01

    The rate and extent of decomposition of soil organic carbon (SOC) is dependent on substrate chemistry and microbial dynamics. Our objectives were to understand the influence of substrate chemistry on microbial processing of carbon (C), and to use model fitting to quantify differences in pool sizes and mineralization rates. We conducted an incubation experiment for 270 days using four uniformly-labeled 14C substrates (glucose, starch, cinnamic acid and stearic acid) on four different soils (a temperate Mollisol, a tropical Ultisol, a sub-arctic Andisol, and an arctic Gelisol). The 14C labeling enabled us to separate CO2 respired from added substrates and from native SOC. Microbial gene copy numbers were quantified at days 4, 30 and 270 using quantitative polymerase chain reaction (qPCR). Substrate C respiration was always higher for glucose than other substrates. Soils with cinnamic and stearic acid lost more native SOC than glucose- and starch-amended soils, despite an initial delay in respiration. Cinnamic and stearic acid amendments also exhibited higher fungal gene copy numbers at the end of incubation compared to unamended soils. We found that 270 days was sufficient to model decomposition of simple substrates (glucose and starch) with three pools, but was insufficient for more complex substrates (cinnamic and stearic acid) and native SOC. This study reveals that substrate quality imparts considerable control on microbial decomposition of newly added and native SOC, and demonstrates the need for multi-year incubation experiments to constrain decomposition parameters for the most recalcitrant fractions of SOC and added substrates.

  10. Substrate quality alters the microbial mineralization of added substrate and soil organic carbon

    Science.gov (United States)

    Jagadamma, S.; Mayes, M. A.; Steinweg, J. M.; Schaeffer, S. M.

    2014-09-01

    The rate and extent of decomposition of soil organic carbon (SOC) is dependent, among other factors, on substrate chemistry and microbial dynamics. Our objectives were to understand the influence of substrate chemistry on microbial decomposition of carbon (C), and to use model fitting to quantify differences in pool sizes and mineralization rates. We conducted an incubation experiment for 270 days using four uniformly labeled 14C substrates (glucose, starch, cinnamic acid and stearic acid) on four different soils (a temperate Mollisol, a tropical Ultisol, a sub-arctic Andisol, and an arctic Gelisol). The 14C labeling enabled us to separate CO2 respired from added substrates and from native SOC. Microbial gene copy numbers were quantified at days 4, 30 and 270 using quantitative polymerase chain reaction (qPCR). Substrate C respiration was always higher for glucose than other substrates. Soils with cinnamic and stearic acid lost more native SOC than glucose- and starch-amended soils. Cinnamic and stearic acid amendments also exhibited higher fungal gene copy numbers at the end of incubation compared to unamended soils. We found that 270 days were sufficient to model the decomposition of simple substrates (glucose and starch) with three pools, but were insufficient for more complex substrates (cinnamic and stearic acid) and native SOC. This study reveals that substrate quality exerts considerable control on the microbial decomposition of newly added and native SOC, and demonstrates the need for multi-year incubation experiments to constrain decomposition parameters for the most recalcitrant fractions of SOC and complex substrates.

  11. Substrate quality alters microbial mineralization of added substrate and soil organic carbon

    Directory of Open Access Journals (Sweden)

    S. Jagadamma

    2014-03-01

    Full Text Available The rate and extent of decomposition of soil organic carbon (SOC is dependent on substrate chemistry and microbial dynamics. Our objectives were to understand the influence of substrate chemistry on microbial processing of carbon (C, and to use model fitting to quantify differences in pool sizes and mineralization rates. We conducted an incubation experiment for 270 days using four uniformly-labeled 14C substrates (glucose, starch, cinnamic acid and stearic acid on four different soils (a temperate Mollisol, a tropical Ultisol, a sub-arctic Andisol, and an arctic Gelisol. The 14C labeling enabled us to separate CO2 respired from added substrates and from native SOC. Microbial gene copy numbers were quantified at days 4, 30 and 270 using quantitative polymerase chain reaction (qPCR. Substrate C respiration was always higher for glucose than other substrates. Soils with cinnamic and stearic acid lost more native SOC than glucose- and starch-amended soils, despite an initial delay in respiration. Cinnamic and stearic acid amendments also exhibited higher fungal gene copy numbers at the end of incubation compared to unamended soils. We found that 270 days was sufficient to model decomposition of simple substrates (glucose and starch with three pools, but was insufficient for more complex substrates (cinnamic and stearic acid and native SOC. This study reveals that substrate quality imparts considerable control on microbial decomposition of newly added and native SOC, and demonstrates the need for multi-year incubation experiments to constrain decomposition parameters for the most recalcitrant fractions of SOC and added substrates.

  12. Chemical constraints governing the origin of metabolism: the thermodynamic landscape of carbon group transformations under mild aqueous conditions

    Science.gov (United States)

    Weber, Arthur L.

    2002-01-01

    The thermodynamics of organic chemistry under mild aqueous conditions was examined in order to begin to understand its influence on the structure and operation of metabolism and its antecedents. Free energies (deltaG) were estimated for four types of reactions of biochemical importance carbon-carbon bond cleavage and synthesis, hydrogen transfer between carbon groups, dehydration of alcohol groups, and aldo-keto isomerization. The energies were calculated for mainly aliphatic groups composed of carbon, hydrogen, and oxygen. The energy values showed (1) that generally when carbon-carbon bond cleavage involves groups from different functional group classes (i.e., carboxylic acids, carbonyl groups, alcohols, and hydrocarbons), the transfer of the shared electron-pair to the more reduced carbon group is energetically favored over transfer to the more oxidized carbon group, and (2) that the energy of carbon-carbon bond transformation is primarily determined by the functional group class of the group that changes oxidation state in the reaction (i.e., the functional group class of the group that donates the shared electron-pair during cleavage, or that accepts the incipient shared electron-pair during synthesis). In contrast, the energy of hydrogen transfer between carbon groups is determined by the functional group class of both the hydrogen-donor group and the hydrogen-acceptor group. From these and other observations we concluded that the chemistry involved in the origin of metabolism (and to a lesser degree modern metabolism) was strongly constrained by (1) the limited redox-based transformation energy of organic substrates that is readily dissipated in a few energetically favorable irreversible reactions; (2) the energy dominance of a few transformation half-reactions that determines whether carbon-carbon bond transformation (cleavage or synthesis) is energetically favorable (deltaG +3.5 kcal/mol); and (3) the dependence of carbon group transformation energy on the

  13. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocities of macroscopic organic aggregates (marine snow

    Directory of Open Access Journals (Sweden)

    M. H. Iversen

    2010-05-01

    Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d−1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregate of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d−1 and 0.20 d−1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The calculated carbon remineralization length scale due to microbial respiration and sinking velocity of mm-large marine aggregates was higher for calcite ballasted aggregates as compared to opal-ballasted aggregates. It varied between 0.0002 m−1 and 0.0030 m−1, and decreased with increasing aggregate size.

  14. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

    Science.gov (United States)

    Iversen, M. H.; Ploug, H.

    2010-09-01

    Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material) and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted), Skeletonema costatum aggregates (opal ballasted), and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted). Overall average carbon-specific respiration rate was ~0.13 d-1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study) vary between 0.08 d-1 and 0.20 d-1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m-1 and 0.0030 m-1, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

  15. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

    Directory of Open Access Journals (Sweden)

    M. H. Iversen

    2010-09-01

    Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d−1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d−1 and 0.20 d−1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m−1 and 0.0030 m−1, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

  16. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocities of macroscopic organic aggregates (marine snow)

    Science.gov (United States)

    Iversen, M. H.; Ploug, H.

    2010-05-01

    Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material) and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted), Skeletonema costatum aggregates (opal ballasted), and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted). Overall average carbon-specific respiration rate was ~0.13 d-1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregate of different composition and sources. Compiled carbon-specific respiration rates (including this study) vary between 0.08 d-1 and 0.20 d-1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The calculated carbon remineralization length scale due to microbial respiration and sinking velocity of mm-large marine aggregates was higher for calcite ballasted aggregates as compared to opal-ballasted aggregates. It varied between 0.0002 m-1 and 0.0030 m-1, and decreased with increasing aggregate size.

  17. Room temperature performance of 4 V aqueous hybrid supercapacitor using multi-layered lithium-doped carbon negative electrode

    Science.gov (United States)

    Makino, Sho; Yamamoto, Rie; Sugimoto, Shigeyuki; Sugimoto, Wataru

    2016-09-01

    Water-stable multi-layered lithium-doped carbon (LixC6) negative electrode using poly(ethylene oxide) (PEO)-lithium bis(trifluoromethansulfonyl)imide (LiTFSI) polymer electrolyte containing N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)imide (PP13TFSI) ionic liquid was developed. Electrochemical properties at 60 °C of the aqueous hybrid supercapacitor using activated carbon positive electrode and a multi-layered LixC6 negative electrode (LixC6 | PEO-LiTFSI | LTAP) without PP13TFSI exhibited performance similar to that using Li anode (Li | PEO-LiTFSI | LTAP). A drastic decrease in ESR was achieved by the addition of PP13TFSI to PEO-LiTFSI, allowing room temperature operation. The ESR of the multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25 °C was 801 Ω cm2, which is 1/6 the value of the multi-layered Li negative electrode with PEO-LiTFSI (5014 Ω cm2). Charge/discharge test of the aqueous hybrid supercapacitor using multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25 °C afforded specific capacity of 20.6 mAh (g-activated carbon)-1 with a working voltage of 2.7-3.7 V, and good long-term capability up to 3000 cycles. Furthermore, an aqueous hybrid supercapacitor consisting of a high capacitance RuO2 nanosheet positive electrode and multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI showed specific capacity of 196 mAh (g-RuO2)-1 and specific energy of 625 Wh (kg-RuO2)-1 in 2.0 M acetic acid-lithium acetate buffered solution at 25 °C.

  18. Immobilized nickel hexacyanoferrate on activated carbons for efficient attenuation of radio toxic Cs(I) from aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • Rice hulls and areca nut wastes are utilized to obtain activated carbons. • Nickel hexacyanoferrate is immobilized on activated carbon samples. • Materials are characterized by SEM–EDX and XRD data. • Materials are employed in attenuation of Cs(I) under batch and column studies. • Possible mechanism is deduced at solid/solution interface. - Abstract: The aim of this study is to immobilize nickel hexacyanoferrate onto the large surface of activated carbons (ACs) precursor to rice hulls and areca nut waste materials. These nickel hexacyanoferrate immobilized materials are then assessed in the effective attenuation of radio logically important cesium ions from aqueous solutions. The solid samples are characterized by the XRD analytical method and surface morphology is obtained from the SEM images. The batch reactor experiments show that an increase in sorptive pH (2.0–10.0) apparently not affecting the high percent uptake of Cs(I). Equilibrium modeling studies suggest that the data are reasonably and relatively fitted well to the Langmuir adsorption isotherm. Kinetic studies show that sorption process is fairly rapid and the kinetic data are fitted well to the pseudo-second order rate model. Increasing the background electrolyte concentration from 0.001 to 0.1 mol/L NaCl causes insignificant decrease in Cs(I) removal which infers the higher selectivity of these materials for Cs(I) from aqueous solutions. Further, the column reactor operations enable to obtain the breakthrough data which are then fitted to the Thomas non-linear equation as to obtain the loading capacity of column for Cs(I). The results show that the modified materials show potential applicability in the attenuation of radio toxic cesium from aqueous solution

  19. Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, Charles R.; Dewers, Thomas A.; Heath, Jason E.; Wang, Yifeng; Matteo, Edward N.; Meserole, Stephen P.; Tallant, David Robert

    2013-09-01

    In the supercritical CO2-water-mineral systems relevant to subsurface CO2 sequestration, interfacial processes at the supercritical fluid-mineral interface will strongly affect core- and reservoir-scale hydrologic properties. Experimental and theoretical studies have shown that water films will form on mineral surfaces in supercritical CO2, but will be thinner than those that form in vadose zone environments at any given matric potential. The theoretical model presented here allows assessment of water saturation as a function of matric potential, a critical step for evaluating relative permeabilities the CO2 sequestration environment. The experimental water adsorption studies, using Quartz Crystal Microbalance and Fourier Transform Infrared Spectroscopy methods, confirm the major conclusions of the adsorption/condensation model. Additional data provided by the FTIR study is that CO2 intercalation into clays, if it occurs, does not involve carbonate or bicarbonate formation, or significant restriction of CO2 mobility. We have shown that the water film that forms in supercritical CO2 is reactive with common rock-forming minerals, including albite, orthoclase, labradorite, and muscovite. The experimental data indicate that reactivity is a function of water film thickness; at an activity of water of 0.9, the greatest extent of reaction in scCO2 occurred in areas (step edges, surface pits) where capillary condensation thickened the water films. This suggests that dissolution/precipitation reactions may occur preferentially in small pores and pore throats, where it may have a disproportionately large effect on rock hydrologic properties. Finally, a theoretical model is presented here that describes the formation and movement of CO2 ganglia in porous media, allowing assessment of the effect of pore size and structural heterogeneity on capillary trapping efficiency. The model results also suggest possible engineering approaches for optimizing trapping capacity and for

  20. Preferential formation of 13C- 18O bonds in carbonate minerals, estimated using first-principles lattice dynamics

    Science.gov (United States)

    Schauble, Edwin A.; Ghosh, Prosenjit; Eiler, John M.

    2006-05-01

    Equilibrium constants for internal isotopic exchange reactions of the type: Ca12C18O16O2+Ca13C16O3↔Ca13C18O16O2+Ca12C16O3 for individual CO 32- groups in the carbonate minerals calcite (CaCO 3), aragonite (CaCO 3), dolomite (CaMg(CO 3) 2), magnesite (MgCO 3), witherite (BaCO 3), and nahcolite (NaHCO 3) are calculated using first-principles lattice dynamics. Calculations rely on density functional perturbation theory (DFPT) with norm-conserving planewave pseudopotentials to determine the vibrational frequencies of isotopically substituted crystals. Our results predict an ˜0.4‰ excess of 13C18O16O22- groups in all studied carbonate minerals at room-temperature equilibrium, relative to what would be expected in a stochastic mixture of carbonate isotopologues with the same bulk 13C/ 12C, 18O/ 16O, and 17O/ 16O ratios. The amount of excess 13C18O16O22- decreases with increasing temperature of equilibration, from 0.5‰ at 0 °C to <0.1‰ at 300 °C, suggesting that measurements of multiply substituted isotopologues of carbonate could be used to infer temperatures of ancient carbonate mineral precipitation and alteration events, even where the δ 18O of coexisting fluids is uncertain. The predicted temperature sensitivity of the equilibrium constant is ˜0.003‰/°C at 25 °C. Estimated equilibrium constants for the formation of 13C18O16O22- are remarkably uniform for the variety of minerals studied, suggesting that temperature calibrations will also be applicable to carbonate mineral