WorldWideScience

Sample records for aqueous carbonate process

  1. 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.

  2. 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

  3. 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

  4. 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

  5. Removal of Cu(II) from aqueous solution using the rice husk carbons prepared by the physical activation process

    International Nuclear Information System (INIS)

    The adsorption of Cu(II) from aqueous solution by carbons prepared from rice husk through pyrolysis and steam activation was studied. The rice husk carbon was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and its pore structure was also examined. After comparing different characteristics of the carbons prepared under different conditions and their adsorption abilities of Cu(II), the optimum temperature for pyrolysis and steam activation was chosen as 700 and 750 oC, respectively, using 3% (V/V) steam as the best activation gas. It was found that the Cu(II) adsorption on the rice husk derived carbons was pH and temperature dependent with an optimum pH value of 5.0, and an equilibrium time of 24 h. The adsorption kinetics and isotherms of Cu(II) by the rice husk derived carbons were also investigated under four different temperatures, and good correlation coefficients were obtained for the pseudo-second-order kinetic models, and the Langmuir isotherm model fitted very well with the experimental data. The mean free energy E (kJ mol-1) obtained in the Dubinin-Radushkevitch (D-R) adsorption isortherm equation indicated a chemical ion-exchange mechanism. Several thermodynamic parameters were also caculated to predict the nature of adsorption process.

  6. Evaluation of Performance Catalytic Ozonation Process with Activated Carbon in the Removal of Humic Acids from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Gh. Asgari

    2011-01-01

    Full Text Available Introduction & Objective: In recent years, the use of alternative disinfectants and the control of natural organic matters are two approaches that are typically applied in water treatment utilities to reduce the formation of chlorinated disinfection by-products. Catalytic ozonation is a new technology used to promote the efficiency of ozonation. The goal of this study was to survey the feasibility application of activated carbon as a catalyst in ozonation process for removal of humic acids from aqueous solution. Materials & Methods: This experimental study has been done in laboratory of water and wastewater chemistry, Tarbiat Modarres University. The solid structure and chemical composition of activated carbon were analyzed by X-ray fluorescence (XRF. Ozonation and catalytic ozonation experiments were performed in a semi-batch reactor and the mass of ozone produced was measured by iodometric titration methods. Concentration changes of humic acid in samples with a concentration of 15 mg/l were determined by using spectrophotometer at an absorbance wavelength of 254 nm. To evaluate the performance of catalytic ozonation in humic acid removal, total organic carbon and trihalomethane formation potential were evaluated and the results were analyzed by Excel software. Results: Catalytic ozone results showed that using activated carbon as a catalyst increased humic acid decomposition up to 11 times and removal efficiency increased with increasing pH (4-12 and catalyst dosage (0.25-1.5 g/250cc. The experimental results showed that catalytic ozonation was most effective in less time (10 min with considerable efficiency (95% compared to the sole ozonation process (SOP. Conclusion: The results indicated that the catalytic ozonation process, compared to SOP, was less affected by radical scavenger, and total organic carbon, and trihalomethane formation potential removal achieved were 30% and 83%, respectively. (Sci J Hamadan Univ Med Sci 2011;17(4:25-33

  7. 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...

  8. Design of a Multisensory Probe for Measuring Carbon Cycle Processes in Aqueous Subterranean Environments

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, Timothy J [ORNL; Kisner, Roger [ORNL; Woodworth, Ken [ORNL; Lenarduzzi, Roberto [ORNL; Frank, Steven Shane [ORNL; McKnight, Timothy E [ORNL

    2015-01-01

    The global carbon cycle describes the exchange of carbon between the atmosphere, terrestrial vegetation, oceans, and soil. Mechanisms involving carbon in sub-terrestrial ecosystems and their impact on climate are not well understood. This lack of understanding limits current climate models and prevents accurate soil-carbon storage predications for future climate conditions. To address the lack of instrumentation for conducting high fidelity measurements of appropriate parameters in the field, a multi-sensory probe using a mix of optical, fiber optic, and electronic technologies to measure CO2, temperature, dissolved oxygen, redox potential, and water level in subsurface environments has been developed. Details of the design, fabrication and laboratory performance verification are presented. Use cases and the anticipated impacts of such measurements on climate models are discussed.

  9. Model development and process simulation of postcombustion carbon capture technology with aqueous AMP/PZ solvent

    NARCIS (Netherlands)

    van der Spek, Mijndert; Arendsen, Richard; Ramirez, Andrea; Faaij, André

    2016-01-01

    This study presents the development, application, and uncertainty analysis of a process simulation model for postcombustion CO2 capture with an AMP/PZ solvent blend based on state of the art knowledge on AMP/PZ solvent technology. The development includes the improvement of the physical property mod

  10. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mars Aqueous Processing System (MAPS) is an innovative method to produce useful building materials from Martian regolith. Acids and bases produced from the regolith...

  11. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Aqueous Processing System (MAPS) is a novel technology for recovering oxygen, iron, and other constituents from lunar and Mars soils. The closed-loop...

  12. Functionalization of Multiwalled Carbon Nanotubes by Solution Plasma Processing in Ammonia Aqueous Solution and Preparation of Composite Material with Polyamide 6

    Science.gov (United States)

    Shirafuji, Tatsuru; Noguchi, Yohei; Yamamoto, Taibou; Hieda, Junko; Saito, Nagahiro; Takai, Osamu; Tsuchimoto, Akiharu; Nojima, Kazuhiro; Okabe, Youji

    2013-12-01

    Solution plasma processing (SPP) has been performed on multiwalled carbon nanotubes (MWCNTs) in ammonia aqueous solution. The MWCNTs, which do not disperse in aqueous solution, uniformly dispersed after the SPP. Only 2 h was required to obtain 10 g of the dispersed MWCNTs, while 7 days and additional chemicals were required for 185 mg in a previous study. The X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy of the SPP-treated MWCNTs revealed that nitrogen- and oxygen-containing groups are formed on the MWCNTs. Serious damage to the MWCNT structure was not observed in the Raman spectrum or transmission electron microscopy images of the SPP-treated MWCNTs. The composite materials prepared using polyamide 6 with the SPP-treated MWCNTs showed better tensile, bending, and impact strength than those prepared with nontreated MWCNTs.

  13. High-performance zno transistors processed via an aqueous carbon-free metal oxide precursor route at temperatures between 80-180 °c

    KAUST Repository

    Lin, Yenhung

    2013-06-25

    An aqueous and carbon-free metal-oxide precursor route is used in combination with a UV irradiation-assisted low-temperature conversion method to fabricate low-voltage ZnO transistors with electron mobilities exceeding 10 cm2/Vs at temperatures <180°C. Because of its low temperature requirements the method allows processing of high-performance transistors onto temperature sensitive substrates such as plastic. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Photoreduction of Carbon Dioxide to Formic Acid in Aqueous Suspension: A Comparison between Phthalocyanine/TiO2 and Porphyrin/TiO2 Catalysed Processes

    Directory of Open Access Journals (Sweden)

    Giuseppe Mele

    2014-12-01

    Full Text Available Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II co-ordinated in the middle of the macrocycles. A comparison between Cu(II phthalocyanines and Cu(II porphyrins indicated that the Cu(II- phthalocyanine sensitizer was more efficient in the photoreduction of CO2 to formic acid, probably due to its favorable reduction potential.

  15. Corrosion inhibitors for carbon steel in neutral aqueous media based on the products of sugar cane processing. 3. Combined inhibitors

    International Nuclear Information System (INIS)

    Combined (mixed) inhibitors of metal corrosion in aqueous media are developed on the fasis of mixtures of 5-nitro furancarboxylic acid salts (nitrofuroat) with inorganic passivators (nitrite, phosphate, tetraborate) or with nitrogen-containing derivatives of furfural (furfurine, furfurylamine). Their efficiency is confirmed by electrochemical and weighing investigations carried outn under lamoratory and industrial conditions

  16. Efficiency of powder activated carbon magnetized by Fe3O4 nanoparticles for amoxicillin removal from aqueous solutions: Equilibrium and kinetic studies of adsorption process

    Directory of Open Access Journals (Sweden)

    Babak Kakavandi

    2014-07-01

    Conclusion: The present study showed that the magnetic activated carbon has high potential for adsorption of amoxicillin, in addition to features like simple and rapid separation. Therefore, it can be used for adsorption and separation of such pollutants from aqueous solutions.

  17. 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.

  18. Process for separating actinide ions from aqueous basic solutions containing carbonates. Verfahren zur Abtrennung von Aktinoidenionen aus waessrigen, basischen, carbonhaltigen Loesungen

    Energy Technology Data Exchange (ETDEWEB)

    Haag, J.; Sameh, A.

    1986-01-09

    The waste liquid is subjected to the following stages of the process: Treatment with concentrated phosphoric acid. Decomposition of the phosphoric acid ester H/sub 3/PO/sub 4/ adduct compounds formed in the first stage. Saponification of the phosphoric acid ester and draining off a saponification product. Cooling the drained off saponification product and separation of the organic phase formed during cooling of the aqueous phase. Burning the organic phase. Returning the aqueous phase to the saponification stage and solidifying the aqueous phases or residues containing the impurities.

  19. 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

  20. Radiation processing of aqueous systems

    International Nuclear Information System (INIS)

    Groundwater contaminated with about 60 μg/L perchloroethylene (PCE) is purified by a combined ozone/electron beam irradiation process for subsequent use as drinking water. The design of the first commercial plant for such a groundwater remediation having a capacity of 108 m3/h is described. The mechanism of the combined ozone/electron beam process for PCE decomposition is discussed with respect to other ozone based advanced oxidation processes like ozone/U.V. and ozone/hydrogen peroxide. The formation of trace amounts of trichloroacetic acid as the only organic by-product in all these processes has been interpreted as an indication that PCE decomposition proceeds via the same mechanism in all cases. (author)

  1. 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.

  2. Aqueous Electrolytes: Model Parameters and Process Simulation

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    This thesis deals with aqueous electrolyte mixtures. The Extended UNIQUAC model is being used to describe the excess Gibbs energy of such solutions. Extended UNIQUAC parameters for the twelve ions Na+, K+, NH4+, H+, Cl-, NO3-, SO42-, HSO4-, OH-, CO32-, HCO3-, and S2O82- are estimated. A computer ...... program including a steady state process simulator for the design, simulation, and optimization of fractional crystallization processes is presented....

  3. 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...

  4. AQUEOUS STABLE FREE RADICAL POLYMERIZATION PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Andrea R. Szkurhan; Michael K. Georges

    2004-01-01

    An overview of aqueous polymerizations, which include emulsion, miniemulsion and suspension polymerizations,under stable free radical polymerization (SFRP) conditions is presented. The success of miniemulsion and suspension SFRP polymerizations is contrasted with the difficulties associated with obtaining a stable emulsion polymerization. A recently developed unique microprecipitation technique is referenced as a means of making submicron sized particles that can be used to achieve a stable emulsion SFRP process.

  5. 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.

  6. CO2 capture using aqueous ammonia: kinetic study and process simulation

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J.M.; Stenby, Erling Halfdan;

    2011-01-01

    Carbon dioxide capture using aqueous ammonia is a post-combustion technology that has shown a good potential. Therefore this process is studied by measuring the rate of absorption of carbon dioxide by aqueous ammonia and by performing process simulation. The rate of absorption of carbon dioxide by...... 0.6. The results were compared with those found for 30 wt% mono-ethanolamine (MEA) solutions.The capture process was simulated successfully using the simulator Aspen Plus coupled with the extended UNIQUAC thermodynamic model available for the NH3–CO2–H2O system. For this purpose, a user model...

  7. Sulfates on Mars: Indicators of Aqueous Processes

    Science.gov (United States)

    Bishop, Janice L.; Lane, Melissa D.; Dyar, M. Darby; Brown, Adrian J.

    2006-01-01

    Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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...

  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. 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.

  15. 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

  16. AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

    Energy Technology Data Exchange (ETDEWEB)

    K. Osseo-Asare; X. Zeng

    2002-01-01

    The objective of this research project is to develop an aqueous biphase extraction process for the treatment of fine coals. Aqueous biphase extraction is an advanced separation technology that relies on the ability of an aqueous system consisting of a water-soluble polymer and another component, e.g., another polymer, an inorganic salt, or a nonionic surfactant, to separate into two immiscible aqueous phases. The principle behind the partition of solid particles in aqueous biphase systems is the physicochemical interaction between the solid surface and the surrounding liquid solution. In order to remove sulfur and mineral matter from fine coal with aqueous biphasic extraction, it is necessary to know the partitioning behavior of coal, as well as the inorganic mineral components. Therefore, in this research emphasis was placed on the partitioning behavior of fine coal particles as well as model fine inorganic particles in aqueous biphase systems.

  17. An advanced aqueous process for nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    To develop an advanced aqueous reprocessing process using a minimal organic solvent and compact equipment to separate U, Pu and long-lived minor actinides from spent nuclear fuels, we have developed a new type of anion exchanger (AR-01) and several novel extraction resins containing a chelating ligand such as CMPO, Cyanex-301 and R-BTP. A hot separation experiment for a spent BWR-fuel solution was carried out by an ion exchange column packed with AR-01. To enhance the separation factor between U and FPs, electrolytic reduction of UO22+ to U+4 was studied using a flow type electrolysis cell with carbon-fiber electrode. Separation behavior of Am(III) from simulated HLW by CMPO and R-BTP impregnated resins were investigated. On the basis of the experimental results, an advanced aqueous process which consists of anion exchange as main separation method, electrolytic reduction for reducing U(VI) to U(IV) and extraction chromatography for MA partitioning has been designed and evaluated preliminarily. (author)

  18. 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

  19. 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.

  20. Process for separating cesium ions from aqueous solutions

    International Nuclear Information System (INIS)

    A precipitation agent is added to the aqueous solution and the resulting precipitate containing Cs+ ions is separated from the solution. By this process, caesium is to be separated selectively compared with other alkaline metal ions with great efficiency from aqueous solutions, particularly aqueous MAW (medium activity waste). This is achieved by using a sodium tetraphenyl borate attracting electrons to the phenyl rings and having substitutes. (orig./PW)

  1. 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

  2. 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

  3. Hydro fuel is produce through aqueous-phase reforming process by using glycerol as by-product from oil palms

    International Nuclear Information System (INIS)

    Full text: The research is aim to study the type of catalysts (e.g. Pt-Ni, Pt and Ni catalysts) that are use to increase the yield of hydrogen gas in the reaction of aqueous-phase reforming (APR) process ,that use glycerol to produce hydrogen gas using steam. The output product of aqueous-phase reforming (APR) process are hydrogen, carbon monoxide and carbon dioxide gases. (author)

  4. AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

    Energy Technology Data Exchange (ETDEWEB)

    K. Osseo-Asare

    2000-06-02

    Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behavior of fly ash in the PEG-2000 Na{sub 2}SO{sub 4}/H{sub 2}O system was studied and the solid in each fraction was characterized by CHN analysis (carbon content), X-ray diffraction (XRD; crystal component), and inductively coupled plasma spectrophotometry (ICP; elemental composition in the ash). In the pH range from 2 to 5, the particles separated into two different layers, i.e., the polymer-rich (top) and salt-rich (bottom) layers. However, above pH 5, the particles in the polymer-rich phase split into two zones. The percent carbon content of the solids in the upper zone ({approximately}80 wt%) was higher than that in the parent sample (63.2 wt%), while the lower zone in the polymer-rich phase had the same percent ash content as the original sample. The particles in the salt-rich phase were mainly composed of ash (with < 4 wt% carbon content). However, when the solid concentration in the whole system increased from 1 wt% to 2 wt%, this 3-fraction phenomenon only occurred above pH 10. XRD results showed that the main crystal components in the ash included quartz, hematite, and mullite. The ICP results showed that Si, Al, and Fe were the major elements in the fly ash, with minor elements of Na, K, Ca, Mg, and Ba. The composition of the ash in the lower zone of the polymer-rich phase remained almost the same as that in the parent fly ash. The largest amount of product ({approximately}60% yield) with the highest carbon content ({approximately}80 wt% C) was obtained in the range pH 6-9. Based on the experimental results obtained, a flowsheet is proposed for the beneficiation of high-carbon fly ash with the aqueous biphase extraction process.

  5. Aqueous phase processing of secondary organic aerosol from isoprene photooxidation

    Science.gov (United States)

    Liu, Y.; Monod, A.; Tritscher, T.; Praplan, A. P.; DeCarlo, P. F.; Temime-Roussel, B.; Quivet, E.; Marchand, N.; Dommen, J.; Baltensperger, U.

    2012-07-01

    Transport of reactive air masses into humid and wet areas is highly frequent in the atmosphere, making the study of aqueous phase processing of secondary organic aerosol (SOA) very relevant. We have investigated the aqueous phase processing of SOA generated from gas-phase photooxidation of isoprene using a smog chamber. The SOA collected on filters was extracted by water and subsequently oxidized in the aqueous phase either by H2O2 under dark conditions or by OH radicals in the presence of light, using a photochemical reactor. Online and offline analytical techniques including SMPS, HR-AMS, H-TDMA, TD-API-AMS, were employed for physical and chemical characterization of the chamber SOA and nebulized filter extracts. After aqueous phase processing, the particles were significantly more hygroscopic, and HR-AMS data showed higher signal intensity at m/z 44 and a lower signal intensity at m/z 43, thus showing the impact of aqueous phase processing on SOA aging, in good agreement with a few previous studies. Additional offline measurement techniques (IC-MS, APCI-MS2 and HPLC-APCI-MS) permitted the identification and quantification of sixteen individual chemical compounds before and after aqueous phase processing. Among these compounds, small organic acids (including formic, glyoxylic, glycolic, butyric, oxalic and 2,3-dihydroxymethacrylic acid (i.e. 2-methylglyceric acid)) were detected, and their concentrations significantly increased after aqueous phase processing. In particular, the aqueous phase formation of 2-methylglyceric acid and trihydroxy-3-methylbutanal was correlated with the consumption of 2,3-dihydroxy-2-methyl-propanal, and 2-methylbutane-1,2,3,4-tetrol, respectively, and an aqueous phase mechanism was proposed accordingly. Overall, the aging effect observed here was rather small compared to previous studies, and this limited effect could possibly be explained by the lower liquid phase OH concentrations employed here, and/or the development of oligomers

  6. 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

  7. Process for the selective separation of uranium, zirconium and/or hafnium and/or molybdenum from a carbonated aqueous solution

    International Nuclear Information System (INIS)

    Process for improving purity of uraniferous liquors by precipitation of Zr and Hf with an alkaline hydroxide. The precipitate containing Zr and eventually Hf and/or Mo is separated from the solution containing eventually still Mo. To improve elimination of impurities the solution is treated by a diluted solution of alakline hydroxide containing 17 g/l of OH- maximum for a pH value above 11 generally between 11.8 and 12.5

  8. Uranium, thorium and rare earth extraction and separation process by processing their chloride aqueous solutions

    International Nuclear Information System (INIS)

    The different steps of the process are the following: uranium and iron extraction by a neutral organic phosphorus compound and thorium and rare earth recovery in an aqueous solution, iron recovery in acid aqueous phase, concentration of the thorium and rare earth aqueous solution followed by thorium extraction with a organic phosphorus compound and rare earth recovery in the aqueous phase, thorium recovery in acid aqueous phase

  9. Aqueous Processing of WC-Co Powders

    OpenAIRE

    Andersson, Karin M.

    2004-01-01

    The object of this work is to obtain a fundamentalunderstanding of the principal issues concerning the handlingof an aqueous WC-Co powder suspension. The WO3 surface layer on the oxidised tungsten carbidepowder dissolves at pH>3 with the tungsten concentrationincreasing linearly with time. Adding cobalt powder to thetungsten carbide suspension resulted in a significant reductionof the dissolution rate at pH<10. Electrokinetic studiesindicated that the reduced dissolution rate may be rel...

  10. 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

  11. 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 ...

  12. 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)

  13. 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

  14. 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

  15. Process simulation of CO2 capture with aqueous ammonia using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Maribo-Mogensen, Bjørn; van Well, Willy J.M.;

    2012-01-01

    The use of aqueous ammonia is a promising option to capture carbon dioxide from power plants thanks to the potential low heat requirement during the carbon dioxide desorption compared to monoethanolamine (MEA) based process. The patented Chilled Ammonia Process developed by Alstom absorbs carbon...... process is necessary.In this work, the performance of the carbon dioxide capture process using aqueous ammonia has been analyzed by process simulation. The Extended UNIQUAC thermodynamic model available for the CO2–NH3–H2O system has been implemented in the commercial simulator Aspen Plus®1 by using a...... same range as the values reported recently for advanced amine processes. Assuming that cold cooling water is available, the electricity consumption remains limited. Hence the Chilled Ammonia Process is a promising option for post combustion carbon dioxide capture....

  16. 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.

  17. Aqueous phase processing of secondary organic aerosol from isoprene photooxidation

    Directory of Open Access Journals (Sweden)

    Y. Liu

    2012-07-01

    Full Text Available Transport of reactive air masses into humid and wet areas is highly frequent in the atmosphere, making the study of aqueous phase processing of secondary organic aerosol (SOA very relevant. We have investigated the aqueous phase processing of SOA generated from gas-phase photooxidation of isoprene using a smog chamber. The SOA collected on filters was extracted by water and subsequently oxidized in the aqueous phase either by H2O2 under dark conditions or by OH radicals in the presence of light, using a photochemical reactor. Online and offline analytical techniques including SMPS, HR-AMS, H-TDMA, TD-API-AMS, were employed for physical and chemical characterization of the chamber SOA and nebulized filter extracts. After aqueous phase processing, the particles were significantly more hygroscopic, and HR-AMS data showed higher signal intensity at m/z 44 and a lower signal intensity at m/z 43, thus showing the impact of aqueous phase processing on SOA aging, in good agreement with a few previous studies. Additional offline measurement techniques (IC-MS, APCI-MS2 and HPLC-APCI-MS permitted the identification and quantification of sixteen individual chemical compounds before and after aqueous phase processing. Among these compounds, small organic acids (including formic, glyoxylic, glycolic, butyric, oxalic and 2,3-dihydroxymethacrylic acid (i.e. 2-methylglyceric acid were detected, and their concentrations significantly increased after aqueous phase processing. In particular, the aqueous phase formation of 2-methylglyceric acid and trihydroxy-3-methylbutanal was correlated with the consumption of 2,3-dihydroxy-2-methyl-propanal, and 2-methylbutane-1,2,3,4-tetrol, respectively, and an aqueous phase mechanism was proposed accordingly. Overall, the aging effect observed here was rather small compared to previous studies, and this limited effect could possibly be explained by the lower liquid phase OH

  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. 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.

  20. 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.

  1. 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.

  2. Aqueous processing of organic compounds in carbonaceous asteroids

    Science.gov (United States)

    Trigo-Rodríguez, Josep Maria; Rimola, Albert; Martins, Zita

    2015-04-01

    There is growing evidence pointing towards a prebiotic synthesis of complex organic species in water-rich undifferentiated bodies. For instance, clays have been found to be associated with complex organic compounds (Pearson et al. 2002; Garvie & Buseck 2007; Arteaga et al. 2010), whereas theoretical calculations have studied the interaction between the organic species and surface minerals (Rimola et al., 2013) as well as surface-induced reactions (Rimola at al. 2007). Now, we are using more detailed analytical techniques to study the possible processing of organic molecules associated with the mild aqueous alteration in CR, CM and CI chondrites. To learn more about these processes we are studying carbonaceous chondrites at Ultra High-Resolution Transmission Electron Microscopy (UHR-TEM). We are particularly interested in the relationship between organics and clay minerals in carbonaceous chondrites (CCs) matrixes (Trigo-Rodríguez et al. 2014, 2015).We want to address two goals: i) identifying the chemical steps in which the organic molecules could have increased their complexity (i.e., surface interaction and catalysis); and ii) studying if the organic matter present in CCs experienced significant processing concomitant to the formation of clays and other minerals at the time in which these planetary bodies experienced aqueous alteration. Here, these two points are preliminarily explored combing experimental results with theoretical calculations based on accurate quantum mechanical methods. References Arteaga O, Canillas A, Crusats J, El-Hachemi Z, Jellison GE, Llorca J, Ribó JM (2010) Chiral biases in solids by effect of shear gradients: a speculation on the deterministic origin of biological homochirality. Orig Life Evol Biosph 40:27-40. Garvie LAJ, Buseck PR (2007) Prebiotic carbon in clays from Orgueil and Ivuna (CI) and Tagish lake (C2 ungrouped) meteorites. Meteorit Planet Sci 42:2111-2117. Pearson VK, Sephton MA, Kearsley AT, Bland AP, Franchi IA, Gilmour

  3. 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.

  4. 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

  5. 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 ...

  6. Aqueous Tape Casting Process with Styrene-acrylic Latex Binder

    Institute of Scientific and Technical Information of China (English)

    CUI Xue-min; OUYANG Shi-xi; HUANG Yong; YU Zhi-yong; ZHAO Shi-ke; WANG Chang-an

    2004-01-01

    A commercial styrene-acrylic latex binder has been investigated as a good binder for aqueous Al2O3 suspensions tape-casting process. This paper focuses on the forming film mechanism of latex binder, the rheological behaviors of the suspensions, physical properties of green tapes and drying process of aqueous slurries with latex binder system. The drying process of the alumina suspensions is shown to follow a two-stage mechanism (the first stage: evaporation controlled process; and the second stage: diffusion controlled process). During the drying stage of the suspensions, the compressive force presses the latex particles and makes them be distorted, which results in cross-linking structure in contacted latex particles of the solidified tapes.A smooth-surface and high-strength green tape was fabricated by aqueous tape casting with latex binder system. The results from the SEM images of the crossing section microstructure of green tapes show that the latex is a very suitable binder for aqueous tape casting.

  7. 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.

  8. 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

  9. A Novel Process for the Aqueous Extraction of Linseed Oil Based on Nitrogen Protection

    OpenAIRE

    Yuan Gao; Ning Wang; Lirong Xu; Xiuzhu Yu

    2015-01-01

    In order to prevent the oxidation of linseed oil and emulsification during extraction process, Nitrogen-protected and Salt-Assisted Aqueous Extraction (NSAE) of linseed oil was investigated in this study. Nitrogen-protected and salt-assisted were found to be the most effectively in weakening oil oxidation and improving the oil yield, respectively. The highest oil recovery of 87.55% was achieved under optimal conditions of sodium carbonate solution concentration (2 mol/L), solution-to-flour ra...

  10. 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.

  11. Process of attack of uraniferous ores by a solution of potassium carbonate and bicarbonate

    International Nuclear Information System (INIS)

    Oxidizing attack process of uraniferous ores by an aqueous solution of potassium carbonate and dicarbonate in which is introduced a gas containing oxygen under pressure. This process allowing a high solubilization of uranium in a soluble salt form

  12. Present status of advanced aqueous separation process technology development

    International Nuclear Information System (INIS)

    In 'the Feasibility study on commercialized fast reactor cycle systems' begun in 1999, the commercialized candidate concept of the process as the advanced aqueous reprocessing system has been examined. This process, named NEXT, includes such advanced process elements as high efficiency dissolution, crystallization, U/Pu/Np co-recovery, and MA recovery. Small scale hot tests of these process elements have been conducted with irradiated fuel of the experimental Fast Reactor 'JOYO' in Chemical Processing Facility (CPF). The prospect of the technical feasibility of the NEXT process is being obtained as a promising candidate concept. (author)

  13. 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.

  14. Carbon dioxide reducing processes; Koldioxidreducerande processer

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Fredrik

    1999-12-01

    This thesis discusses different technologies to reduce or eliminate the carbon dioxide emissions, when a fossil fuel is used for energy production. Emission reduction can be accomplished by separating the carbon dioxide for storage or reuse. There are three different ways of doing the separation. The carbon dioxide can be separated before the combustion, the process can be designed so that the carbon dioxide can be separated without any energy consumption and costly systems or the carbon dioxide can be separated from the flue gas stream. Two different concepts of separating the carbon dioxide from a combined cycle are compared, from the performance and the economical point of view, with a standard natural gas fired combined cycle where no attempts are made to reduce the carbon dioxide emissions. One concept is to use absorption technologies to separate the carbon dioxide from the flue gas stream. The other concept is based on a semi-closed gas turbine cycle using carbon dioxide as working fluid and combustion with pure oxygen, generated in an air-separating unit. The calculations show that the efficiency (power) drop is smaller for the first concept than for the second, 8.7 % points compared to 13.7 % points, when power is produced. When both heat and power are produced, the relation concerning the efficiency (power) remains. Regarding the overall efficiency (heat and power) the opposite relation is present. A possible carbon dioxide tax must exceed 0.21 SEK/kg CO{sub 2} for it to be profitable to separate carbon dioxide with any of these technologies.

  15. Differential capacitance probe for process control involving aqueous dielectric fluids

    Science.gov (United States)

    Svoboda, John M.; Morrison, John L.

    2002-10-08

    A differential capacitance probe device for process control involving aqueous dielectric fluids is disclosed. The device contains a pair of matched capacitor probes configured in parallel, one immersed in a sealed container of reference fluid, and the other immersed in the process fluid. The sealed container holding the reference fluid is also immersed in the process fluid, hence both probes are operated at the same temperature. Signal conditioning measures the difference in capacitance between the reference probe and the process probe. The resulting signal is a control error signal that can be used to control the process.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Modeling Non-aqueous Phase Liquid Displacement Process

    Institute of Scientific and Technical Information of China (English)

    Yang Zhenqing; Shao Changjin; Zhou Guanggang; Qiu Chao

    2007-01-01

    A pore-network model physically based on pore level multiphase flow was used to study the water-non-aqueous phase liquid (NAPL) displacement process, especially the effects of wettability, water-NAPL interfacial tension, the fraction of NAPL-wet pores, and initial water saturation on the displacement. The computed data show that with the wettability of the mineral surfaces changing from strongly water-wet to NAPL-wet, capillary pressure and the NAPL relative permeability gradually decrease, while water-NAPL interfacial tension has little effect on water relative permeability, but initial water saturation has a strong effect on water and NAPL relative permeabilities. The analytical results may help to understand the micro-structure displacement process of non-aqueous phase liquid and to provide the theoretical basis for controlling NAPL migration.

  2. 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

  3. 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

  4. 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

  5. Carbon activation process for increased surface accessibility in electrochemical capacitors

    Science.gov (United States)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  6. 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

  7. Unexpected toxicity to aquatic organisms of some aqueous bisphenol A samples treated by advanced oxidation processes.

    Science.gov (United States)

    Tišler, Tatjana; Erjavec, Boštjan; Kaplan, Renata; Şenilă, Marin; Pintar, Albin

    2015-01-01

    In this study, photocatalytic and catalytic wet-air oxidation (CWAO) processes were used to examine removal efficiency of bisphenol A from aqueous samples over several titanate nanotube-based catalysts. Unexpected toxicity of bisphenol A (BPA) samples treated by means of the CWAO process to some tested species was determined. In addition, the CWAO effluent was recycled five- or 10-fold in order to increase the number of interactions between the liquid phase and catalyst. Consequently, the inductively coupled plasma mass spectrometry (ICP-MS) analysis indicated higher concentrations of some toxic metals like chromium, nickel, molybdenum, silver, and zinc in the recycled samples in comparison to both the single-pass sample and the photocatalytically treated solution. The highest toxicity of five- and 10-fold recycled solutions in the CWAO process was observed in water fleas, which could be correlated to high concentrations of chromium, nickel, and silver detected in tested samples. The obtained results clearly demonstrated that aqueous samples treated by means of advanced oxidation processes should always be analyzed using (i) chemical analyses to assess removal of BPA and total organic carbon from treated aqueous samples, as well as (ii) a battery of aquatic organisms from different taxonomic groups to determine possible toxicity. PMID:26114268

  8. 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.

  9. 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

  10. 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.

  11. Deuterium isotope effect on swelling process in aqueous polymer gels

    International Nuclear Information System (INIS)

    The deuterium isotope effects on the swelling process of typical aqueous polymer gels (poly(N-isopropylacrylamide) gel and polyacrylamide gel) have been investigated in this study. The swelling times of both the poly(N-isopropylacrylamide) gel and the polyacrylamide gel in heavy water are longer than those in water. The deuterium isotope effect in the swelling process of gels is mainly arising from the higher viscosity in heavy water than in water. The additional deuterium isotope effect on the diffusion coefficient related to the swelling process should be due to the larger microscopic friction arising from the stronger polymer-solvent interaction in heavier water than in water. We also discuss in this paper the deuterium isotope effects on the size of the aqueous gels in the equilibrium state. Interestingly, the size in the equilibrium state of poly(N-isopropylacrylamide) gel in heavy water is larger than that in water. In contrast to poly(N-isopropylacrylamide) gel, the size in the equilibrium state of polyacrylamide gel in heavy water is smaller than that in water. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  12. 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

  13. 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...

  14. Chemical precipitation processes for the treatment of aqueous radioactive waste

    International Nuclear Information System (INIS)

    Chemical precipitation by coagulation-flocculation and sedimentation has been commonly used for many years to treat liquid (aqueous) radioactive waste. This method allows the volume of waste to be substantially reduced for further treatment or conditioning and the bulk of the waste to de discharged. Chemical precipitation is usually applied in combination with other methods as part of a comprehensive waste management scheme. As with any other technology, chemical precipitation is constantly being improved to reduce cost to increase the effectiveness and safety on the entire waste management system. The purpose of this report is to review and update the information provided in Technical Reports Series No. 89, Chemical Treatment of Radioactive Wastes, published in 1968. In this report the chemical methods currently in use for the treatment of low and intermediate level aqueous radioactive wastes are described and illustrated. Comparisons are given of the advantages and limitations of the processes, and it is noted that good decontamination and volume reduction are not the only criteria according to which a particular process should be selected. Emphasis has been placed on the need to carefully characterize each waste stream, to examine fully the effect of segregation and the importance of looking at the entire operation and not just the treatment process when planning a liquid waste treatment facility. This general approach includes local requirements and possibilities, discharge authorization, management of the concentrates, ICRP recommendations and economics. It appears that chemical precipitation process and solid-liquid separation techniques will continue to be widely used in liquid radioactive waste treatment. Current research and development is showing that combining different processes in one treatment plant can provide higher decontamination factors and smaller secondary waste arisings. Some of these processes are already being incorporated into new and

  15. 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.

  16. 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....

  17. 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.

  18. 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

  19. 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.

  20. Sustainable carbon materials from hydrothermal processes

    CERN Document Server

    Titirici, Maria-Magdalena

    2013-01-01

    The production of low cost and environmentally friendly high performing carbon materials is crucial for a sustainable future. Sustainable Carbon Materials from Hydrothermal Processes describes a sustainable and alternative technique to produce carbon from biomass in water at low temperatures, a process known as Hydrothermal Carbonization (HTC). Sustainable Carbon Materials from Hydrothermal Processes presents an overview of this new and rapidly developing field, discussing various synthetic approaches, characterization of the final products, and modern fields of application fo

  1. Biological removal of metal ions from aqueous process streams

    International Nuclear Information System (INIS)

    Aqueous waste streams from nuclear fuel processing operations may contain trace quantities of heavy metals such as uranium. Conventional chemical and physical treatment may be ineffective or very expensive when uranium concentrations in the range of 10 to 100 g/m3 must be reduced to 1 g/m3 or less. The ability of some microorganisms to adsorb or complex dissolved heavy metals offers an alternative treatment method. Uranium uptake by Saccharomyces cerevisiae NRRL Y-2574 and a strain of Pseudomonas aeruginosa was examined to identify factors which might affect a process for the removal of uranium from wastewater streams. At uranium concentrations in the range of 10 to 500 g/m3, where the binding capacity of the biomass was not exceeded, temperature, pH, and initial uranium concentration were found to influence the rate of uranium uptake, but not the soluble uranium concentration at equilibrium. 6 figs

  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. 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.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  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. 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)

  12. 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.

  13. Humic acid removal from aqueous solutions by peroxielectrocoagulation process

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Yazdanbakhsh

    2015-06-01

    Full Text Available Background: Natural organic matter is the cause of many problems associated with water treatment such as the presence of disinfection by-products (DBPs and membrane fouling during water filtration. In this study, the performance of the peroxi-electrocoagulation process (PEP was investigated for the removal of humic acids (HAs from aqueous solutions. Methods: PEP was carried out for the removal of HA using a plexiglas reactor with a volume of 2 L and fitted with iron electrodes and a direct current supply (DC. Samples were taken at various amounts of pH (2-4, current density (1 and 2A/cm2, hydrogen peroxide (50-150 mg/L and reaction time (5-20 minutes and then filtered to remove sludge formed during reaction. Finally, the HA concentration was measured by UV absorbance at 254 nm (UV254. Results: Results indicated that increasing the concentration of H2O2 from 50 to 150 mg/L increased HA removal efficiency from 83% to 94.5%. The highest removal efficiency was observed at pH 3.0; by increasing the pH to the alkaline range, the efficiency of the process was reduced. It was found that HA removal efficiency was high in current density 1A/cm2. Increasing current density up to 1 A cm-2 caused a decrease in removal efficiency. Results of this study showed that under the optimum operating range for the process ([current density] = 1A/cm2, [hydrogen peroxide concentration] = 150 mg/L, [reaction time]= 20 minutes and [pH]= 3.0, HA removal efficiency reached 98%. Conclusion: It can be concluded that PEP has the potential to be utilized for cost-effective removal of HA from aqueous solutions.

  14. Aqueous recovery of plutonium from pyrochemical processing residues

    International Nuclear Information System (INIS)

    Pyrochemical processes provide rapid methods to reclaim plutonium from scrap residues. Frequently, however, these processes yield an impure plutonium product and waste residues that are contaminated with actinides and are therefore nondiscardable. The Savannah River Laboratory and Plant and the Rocky Flats Plant are jointly developing new processes using both pyrochemistry and aqueous chemistry to generate pure product and discardable waste. An example of residue being treated is that from the molten salt extraction (MSE), a mixture of NaCl, KCl, MgCl2, PuCl3, AmCl3, PuO2, and Pu0. This mixture is scrubbed with molten aluminum containing a small amount of magnesium to produce a nonhomogeneous Al-Pu-Am-Mg alloy. This process, which rejects most of the NaCl-KCl-MgCl2 salts, results in a product easily dissolved in 6M HNO3 -0.1M HF. Any residual chloride in the product is removed by precipitation with Hg(I) followed by centrifuging. Plutonium and americium are then separated by the standard Purex process. The americium, initially diverted to the solvent extraction waste stream, can either be recovered or sent to waste

  15. 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.

  16. 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...

  17. A Novel Process for the Aqueous Extraction of Linseed Oil Based on Nitrogen Protection

    Directory of Open Access Journals (Sweden)

    Yuan Gao

    2015-09-01

    Full Text Available In order to prevent the oxidation of linseed oil and emulsification during extraction process, Nitrogen-protected and Salt-Assisted Aqueous Extraction (NSAE of linseed oil was investigated in this study. Nitrogen-protected and salt-assisted were found to be the most effectively in weakening oil oxidation and improving the oil yield, respectively. The highest oil recovery of 87.55% was achieved under optimal conditions of sodium carbonate solution concentration (2 mol/L, solution-to-flour ratio (10 mL/g and temperature (60°C. Moreover, there were no significant variations in physicochemical properties of Nitrogen-protected and Salt-assisted Aqueous Extracted Oil (NSAEO and Salt-Assisted Aqueous Extracted Oil (SAEO, but NSAEO showed better oxidation stability. Additionally, NSAEO had a higher content of linoleic acid (18.97±0.05%, α-linolenic acid (56.48±0.12%. Therefore, NSAEO is a promising and environmental-friendly technique for oil extraction in the food industry.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Chemical Processing in High-Pressure Aqueous Environments. 9. Process Development for Catalytic Gasification of Algae Feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Olarte, Mariefel V.; Zacher, Alan H.

    2012-07-26

    Through the use of a metal catalyst, gasification of wet algae slurries can be accomplished with high levels of carbon conversion to gas at relatively low temperature (350 C). In a pressurized-water environment (20 MPa), near-total conversion of the organic structure of the algae to gases has been achieved in the presence of a supported ruthenium metal catalyst. The process is essentially steam reforming, as there is no added oxidizer or reagent other than water. In addition, the gas produced is a medium-heating value gas due to the synthesis of high levels of methane, as dictated by thermodynamic equilibrium. As opposed to earlier work, biomass trace components were removed by processing steps so that they did not cause processing difficulties in the fixed catalyst bed tubular reactor system. As a result, the algae feedstocks, even those with high ash contents, were much more reliably processed. High conversions were obtained even with high slurry concentrations. Consistent catalyst operation in these short-term tests suggested good stability and minimal poisoning effects. High methane content in the product gas was noted with significant carbon dioxide captured in the aqueous byproduct in combination with alkali constituents and the ammonia byproduct derived from proteins in the algae. High conversion of algae to gas products was found with low levels of byproduct water contamination and low to moderate loss of carbon in the mineral separation step.

  4. 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.

  5. Liquid-liquid equilibriums in aqueous solutions of demixing amines loaded with gas for CO 2 capture processes

    OpenAIRE

    Coulier, Y; Lowe, A.; Coxam, Jean Yves; Ballerat-Busserolles, Karine

    2015-01-01

    International audience Carbon Capture and Storage (CCS) is a solid option for CO2 mitigation in the atmosphere. One option is the CO2 capture from industrial effluents followed by storage in secured sites. Capture processes are based on selective absorption/desorption cycles of gas in aqueous solutions of amines[1]. The cost of CO2 treatment with classical alkanolamines is a limitation for the use of this technology. The development of breakthrough technologies is needed to optimize the se...

  6. 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.

  7. 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

  8. 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

  9. Carbon dioxide removal in gas treating processes

    Energy Technology Data Exchange (ETDEWEB)

    Lidal, H.

    1992-06-01

    The main contribution of this work is the development of a simple and reliable modelling technique on carbon dioxide removal describing the vapor-liquid equilibria of CO{sub 2} in aqueous alkanolamine solutions. By making use of measured pH data, the author has circumvented the problem of estimating interaction parameters, activity coefficients, and equilibrium constants in the prediction of vapor-liquid equilibria. The applicability of the model is best demonstrated on the tertiary amine system using MDEA. For this system, the VLE is accurately represented for temperatures in the range 25 to 140{sup o}C, for CO{sub 2} loadings from 0.001 to 1 mol/mol, and for amine molarities usually encountered in acid gas treating processes. The absorption of CO{sub 2} into solutions containing the sterically hindered amine AMP, is also well described by the model. The equilibrium of CO{sub 2} in mixed solvents containing a glycol (TEG,DEG) and an alkonolamine (MEA,DEA) has been measured at temperatures encountered in the absorption units. An equilibrium model has been developed for the CO{sub 2}/TEG/MEA system for estimation of CO{sub 2} partial pressures, covering loadings and temperatures for both absorption and desorption conditions. An important spin-off of the work described is that two new experimental set-ups have been designed and built. 154 refs., 38 figs., 22 tabs.

  10. Carbon dioxide removal in gas treating processes

    International Nuclear Information System (INIS)

    The main contribution of this work is the development of a simple and reliable modelling technique on carbon dioxide removal describing the vapor-liquid equilibria of CO2 in aqueous alkanolamine solutions. By making use of measured pH data, the author has circumvented the problem of estimating interaction parameters, activity coefficients, and equilibrium constants in the prediction of vapor-liquid equilibria. The applicability of the model is best demonstrated on the tertiary amine system using MDEA. For this system, the VLE is accurately represented for temperatures in the range 25 to 140oC, for CO2 loadings from 0.001 to 1 mol/mol, and for amine molarities usually encountered in acid gas treating processes. The absorption of CO2 into solutions containing the sterically hindered amine AMP, is also well described by the model. The equilibrium of CO2 in mixed solvents containing a glycol (TEG,DEG) and an alkonolamine (MEA,DEA) has been measured at temperatures encountered in the absorption units. An equilibrium model has been developed for the CO2/TEG/MEA system for estimation of CO2 partial pressures, covering loadings and temperatures for both absorption and desorption conditions. An important spin-off of the work described is that two new experimental set-ups have been designed and built. 154 refs., 38 figs., 22 tabs

  11. 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.

  12. 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.

  13. Processing and Structure of Carbon Nanofiber Paper

    Directory of Open Access Journals (Sweden)

    Zhongfu Zhao

    2009-01-01

    Full Text Available A unique concept of making nanocomposites from carbon nanofiber paper was explored in this study. The essential element of this method was to design and manufacture carbon nanofiber paper with well-controlled and optimized network structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under various processing conditions, including different types of carbon nanofibers, solvents, dispersants, and acid treatment. The morphologies of carbon nanofibers within the nanofiber paper were characterized with scanning electron microscopy (SEM. In addition, the bulk densities of carbon nanofiber papers were measured. It was found that the densities and network structures of carbon nanofiber paper correlated to the dispersion quality of carbon nanofibers within the paper, which was significantly affected by papermaking process conditions.

  14. Processes for working-up an aqueous fluosilicic acid solution

    Directory of Open Access Journals (Sweden)

    Alpha O. Toure

    2012-11-01

    Full Text Available Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6%– 7%solution with yields of about 70% – 80%by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol. Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

  15. Phase diagrams of ionic liquids-based aqueous biphasic systems as a platform for extraction processes

    International Nuclear Information System (INIS)

    Highlights: • Novel ABS based in ionic liquids were determined as a platform for distinct extraction processes. • The effect of pH, IL cation core, alkyl side chain length, IL anion nature, and salt nature on the ABS formation was investigated. • The ability to form ABS increases with the pH and alkyl chain length for all systems studied. • The ILs cation core and anion nature effect on the ABS formation is dominated by the IL (hydrophobic/hydrophilic) nature. • The effect of the different salts depends of the ionic liquid nature and salt valency. - Abstract: In the past few years, ionic liquid-based aqueous biphasic systems have become the subject of considerable interest as a promising technique for the extraction and purification of several macro/biomolecules. Aiming at developing guidelines for more benign and efficient extraction processes, phase diagrams for aqueous biphasic systems composed of ionic liquids and inorganic/organic salts are here reported. Several combinations of ionic liquid families (imidazolium, pyridinium, phosphonium, quaternary ammonium and cholinium) and salts [potassium phosphate buffer (KH2PO4/K2HPO4 at pH 7), potassium citrate buffer (C6H5K3O7/C6H8O7 at pH 5, 6, 7 and 8) and potassium carbonate (K2CO3 at pH ∼13)] were evaluated to highlight the influence of the ionic liquid structure (cation core, anion and alkyl chain length), the pH and the salt nature on the formation of aqueous biphasic systems. The binodal curves and respective tie-lines reported for these systems were experimentally determined at (298 ± 1) K. In general, the ability to promote the aqueous biphasic systems formation increases with the pH and alkyl chain length. While the influence of the cation core and anion nature of the ionic liquids on their ability to form aqueous biphasic systems closely correlates with ionic liquids capacity to be hydrated by water, the effect of the different salts depends of the ionic liquid nature and salt valency

  16. 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

  17. 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 ...

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  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. 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

  5. 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.

  6. 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

  7. Oxidizing attack process of uranium ore by a carbonated liquor

    International Nuclear Information System (INIS)

    A continuous process for digesting a uraniferous ore by oxidation with a recycling aqueous liquor containing alkaline carbonates and bicarbonates in solution as well as uranium in a concentration close to its solubility limit at digestion temperature, and of recuperation of the precipitated uranium within the solid phase remaining after digestion. The digestion is carried out by spraying oxygen into the hot reactional medium in order not only to permit oxidation of the uranium and its solubilization but also to ensure that the sulphides of impurities and organic substances present in the ore are oxidized

  8. 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

  9. Sorption of Ni(II), Cu(II) and Fe(III) ions from Aqueous Solutions Using Activated Carbon

    International Nuclear Information System (INIS)

    An activated carbon was tested for its ability to remove transition metal ions from aqueous solutions. Physical, chemical and liquid-phase adsorption characterizations of the carbon were done following standard procedures. Studies on the removal of Ni(II), Cu(II) and Fe(III) ions were attempted by varying adsorbate dose, pH of the metal ion solution and time in batch mode. The equilibrium adsorption data were fitted with Freundlich and Langmuir and the isotherm constants were evaluated, equilibrium time of the different three metal ions were determined. pH was found to have a significant role to play in the adsorption. The processes were endothermic and the thermodynamic parameters were evaluated. Desorption studies indicate that ion-exchange mechanism is operating

  10. High-performance aqueous asymmetric supercapacitor based on carbon nanofibers network and tungsten trioxide nanorod bundles electrodes

    International Nuclear Information System (INIS)

    The demand for high-performance energy storage devices such as supercapacitors and lithium-ion batteries has been increasing to meet the application requirements of renewable energy systems. Here, high energy density aqueous asymmetric supercapacitor (ASC) is assembled based on carbon nanofibers (CNF) network positive electrode and tungsten trioxide (WO3) nanorod bundles negative electrode. Polyaniline-based CNF are prepared by direct carbonization of polyaniline nanofibers. WO3 nanorod bundles are synthesized via a simple sodium chloride assisted hydrothermal process. The CNF//WO3 ASC device operates with a voltage of 1.6 V and achieved a high energy density of 35.3 Wh kg−1 at a power density of 314 W kg−1. Furthermore, the device shows an excellent cycling performance with capacitance retention of 88% after 1000 cycles

  11. Chemical and structural evaluation of activated carbon prepared from jute sticks for Brilliant Green dye removal from aqueous solution.

    Science.gov (United States)

    Asadullah, Mohammad; Asaduzzaman, Mohammad; Kabir, Mohammad Shajahan; Mostofa, Mohammad Golam; Miyazawa, Tomohisa

    2010-02-15

    Activated carbons have been prepared from jute sticks by chemical activation using ZnCl(2) and physical activation using steam for the removal of Brilliant Green dye from aqueous solution. The activated carbons and charcoal prepared from jute sticks were characterized by evaluating the surface chemistry, structural features and surface morphology. The maximum BET surface area was obtained to be 2304 m(2)/g for chemical activated carbon (ACC) while it is 730 and 80 m(2)/g for steam activated carbon (ACS) and charcoal, respectively. The FT-IR spectra exhibited that the pyrolysis and steam activation of jute sticks resulted in the release of aliphatic and O-containing functional groups by thermal effect. However, the release of functional groups is the effect of chemical reaction in the ZnCl(2) activation process. A honeycomb-type carbon structure in ACC was formed as observed on SEM images. Although charcoal and ACC were prepared at 500 degrees C the ACC exhibited much lower Raman sensitivity due to the formation of condensed aromatic ring systems. Due to high surface area and high porous structure with abundance of functional groups, the ACC adsorbed dye molecules with much higher efficiency than those of ACS and charcoal. PMID:19815339

  12. 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

  13. 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.)

  14. Fabrication of conductive polymer nanofibers through SWNT supramolecular functionalization and aqueous solution processing.

    Science.gov (United States)

    Naeem, Fahim; Prestayko, Rachel; Saem, Sokunthearath; Nowicki, Lauren; Imit, Mokhtar; Adronov, Alex; Moran-Mirabal, Jose M

    2015-10-01

    Polymeric thin films and nanostructured composites with excellent electrical properties are required for the development of advanced optoelectronic devices, flexible electronics, wearable sensors, and tissue engineering scaffolds. Because most polymers available for fabrication are insulating, one of the biggest challenges remains the preparation of inexpensive polymer composites with good electrical conductivity. Among the nanomaterials used to enhance composite performance, single walled carbon nanotubes (SWNTs) are ideal due to their unique physical and electrical properties. Yet, a barrier to their widespread application is that they do not readily disperse in solvents traditionally used for polymer processing. In this study, we employed supramolecular functionalization of SWNTs with a conjugated polyelectrolyte as a simple approach to produce stable aqueous nanotube suspensions, that could be effortlessly blended with the polymer poly(ethyleneoxide) (PEO). The homogeneous SWNT:PEO mixtures were used to fabricate conductive thin films and nanofibers with improved conductivities through drop casting and electrospinning. The physical characterization of electrospun nanofibers through Raman spectroscopy and SEM revealed that the SWNTs were uniformly incorporated throughout the composites. The electrical characterization of SWNT:PEO thin films allowed us to assess their conductivity and establish a percolation threshold of 0.1 wt% SWNT. Similarly, measurement of the nanofiber conductivity showed that the electrospinning process improved the contact between nanotube complexes, resulting in conductivities in the S m(-1) range with much lower weight loading of SWNTs than their thin film counterparts. The methods reported for the fabrication of conductive nanofibers are simple, inexpensive, and enable SWNT processing in aqueous solutions, and offer great potential for nanofiber use in applications involving flexible electronics, sensing devices, and tissue engineering

  15. Fabrication of conductive polymer nanofibers through SWNT supramolecular functionalization and aqueous solution processing

    Science.gov (United States)

    Naeem, Fahim; Prestayko, Rachel; Saem, Sokunthearath; Nowicki, Lauren; Imit, Mokhtar; Adronov, Alex; Moran-Mirabal, Jose M.

    2015-10-01

    Polymeric thin films and nanostructured composites with excellent electrical properties are required for the development of advanced optoelectronic devices, flexible electronics, wearable sensors, and tissue engineering scaffolds. Because most polymers available for fabrication are insulating, one of the biggest challenges remains the preparation of inexpensive polymer composites with good electrical conductivity. Among the nanomaterials used to enhance composite performance, single walled carbon nanotubes (SWNTs) are ideal due to their unique physical and electrical properties. Yet, a barrier to their widespread application is that they do not readily disperse in solvents traditionally used for polymer processing. In this study, we employed supramolecular functionalization of SWNTs with a conjugated polyelectrolyte as a simple approach to produce stable aqueous nanotube suspensions, that could be effortlessly blended with the polymer poly(ethyleneoxide) (PEO). The homogeneous SWNT:PEO mixtures were used to fabricate conductive thin films and nanofibers with improved conductivities through drop casting and electrospinning. The physical characterization of electrospun nanofibers through Raman spectroscopy and SEM revealed that the SWNTs were uniformly incorporated throughout the composites. The electrical characterization of SWNT:PEO thin films allowed us to assess their conductivity and establish a percolation threshold of 0.1 wt% SWNT. Similarly, measurement of the nanofiber conductivity showed that the electrospinning process improved the contact between nanotube complexes, resulting in conductivities in the S m-1 range with much lower weight loading of SWNTs than their thin film counterparts. The methods reported for the fabrication of conductive nanofibers are simple, inexpensive, and enable SWNT processing in aqueous solutions, and offer great potential for nanofiber use in applications involving flexible electronics, sensing devices, and tissue engineering

  16. Analysis of residual organic materials in aqueous radioactive streams from the Purex process

    International Nuclear Information System (INIS)

    New solid phase extraction methods have been developed to allow determination of residual normal paraffin hydrocarbon (NPH) and tri-n-butyl phosphate (TBP) in aqueous radioactive streams from the Purex process. The techniques concentrate organic materials and separate them from radioactive species for analysis by gas chromatography. TBP and NPH have good radiolytic and chemical stability and have low aqueous solubility. However, they can contaminate aqueous streams and cause processing difficulties. Knowledge of the concentration of organic materials in aqueous waste is useful in assessing impact on pollution control equipment. The storage quality of diluent-washed aqueous plutonium product solution can be determined by a gas chromatographic analysis for residual TBP. 4 refs., 1 fig., 7 tabs

  17. Significant Performance Enhancement in Asymmetric Supercapacitors based on Metal Oxides, Carbon nanotubes and Neutral Aqueous Electrolyte

    OpenAIRE

    Arvinder Singh; Amreesh Chandra

    2015-01-01

    Amongst the materials being investigated for supercapacitor electrodes, carbon based materials are most investigated. However, pure carbon materials suffer from inherent physical processes which limit the maximum specific energy and power that can be achieved in an energy storage device. Therefore, use of carbon-based composites with suitable nano-materials is attaining prominence. The synergistic effect between the pseudocapacitive nanomaterials (high specific energy) and carbon (high specif...

  18. 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.

  19. Ancient Impact and Aqueous Processes at Endeavour Crater, Mars

    OpenAIRE

    Knoll, Andrew Herbert; Squyres, S. W.; Arvidson, R. E.; Bell, J. F.; Calef, F., III; Clark, B.C.; Cohen, B. A.; Crumpler, L. A.; P.A. Souza; Farrand, W. H.; Gellert, R.; Grant, J; Hurowitz, J. A.; Herkenhoff, K. E.; J. R. Johnson

    2012-01-01

    The rover Opportunity has investigated the rim of Endeavour Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest hydrothermal alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing...

  20. Spherical carbons: Synthesis, characterization and activation processes

    OpenAIRE

    Romero Anaya, Aroldo José; Ouzzine, Mohammed; Lillo Ródenas, María Ángeles; Linares Solano, Ángel

    2014-01-01

    Spherical carbons have been prepared through hydrothermal treatment of three carbohydrates (glucose, saccharose and cellulose). Preparation variables such as treatment time, treatment temperature and concentration of carbohydrate have been analyzed to obtain spherical carbons. These spherical carbons can be prepared with particle sizes larger than 10 μm, especially from saccharose, and have subsequently been activated using different activation processes (H3PO4, NaOH, KOH or physical activati...

  1. 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

  2. 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)

  3. 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.

  4. Pretreatment of rice straw with combined process using dilute sulfuric acid and aqueous ammonia

    OpenAIRE

    Kim, Sung Bong; Lee, Sang Jun; Lee, Ju Hun; Jung, You Ree; Thapa, Laxmi Prasad; Kim, Jun Seok; Um, Youngsoon; Park, Chulhwan; Kim, Seung Wook

    2013-01-01

    Background Use of lignocellulosic biomass has received attention lately because it can be converted into various versatile chemical compounds by biological processes. In this study, a two-step pretreatment with dilute sulfuric acid and aqueous ammonia was performed efficiently on rice straw to obtain fermentable sugar. The soaking in aqueous ammonia process was also optimized by a statistical method. Results Response surface methodology was employed. The determination coefficient (R2) value w...

  5. Equilibrium and kinetics study on the adsorption of perfluorooctanoic acid from aqueous solution onto powdered activated carbon

    International Nuclear Information System (INIS)

    Powdered activated carbon (PAC) was applied to remove perfluorooctanoic acid (PFOA) from the aqueous PFOA solution in this study. Contact time, adsorbent dose and temperature were analyzed as the effect factors in the adsorption reaction. The contact time of maximum PFOA uptake was around 1 h while the sorption removal efficiency increased with the PAC concentrations. And the process of adsorption increased from 303 K to 313 K and then decreased from 313 K to 323 K. Among four applied models, the experimental isotherm data were discovered to follow Langmuir isotherm model more closely. Thermodynamically, adsorption was endothermic because enthalpy, entropy and Gibbs constants were 198.5 kJ/mol, 0.709 kJ/mol/K and negative, respectively, which also indicated that the adsorption process was spontaneous and feasible. From kinetic analysis, the adsorption was suggested to be pseudo-second-order model. The adsorption of PFOA on the PAC was mainly controlled by particle diffusion.

  6. 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

  7. 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

  8. Hexavalent chromium removal from aqueous solution by algal bloom residue derived activated carbon: Equilibrium and kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hong; Tang Yi; Cai Dongqing; Liu Xianan; Wang Xiangqin [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang Qing, E-mail: huangq@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Yu Zengliang, E-mail: zlyu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2010-09-15

    A novel approach to prepare activated carbon from blue-green algal bloom residue has been tried for first time and its adsorption capability to remove hexavalent chromium Cr(VI) from aqueous solution has been examined. For this algal bloom residue derived activated carbon, the physical characters regarding adsorption capability were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform infrared (FTIR) spectroscopy. Batch studies showed that initial pH, absorbent dosage, and initial concentration of Cr(VI) were important parameters for Cr(VI) absorption. It was found that initial pH of 1.0 was most favorable for Cr(VI) removal. The adsorption process followed the pseudo-second-order equation and Freundlich isotherm. The maximum adsorption capacity for Cr(VI) was 155.52 mg g{sup -1} in an acidic medium, which is comparable to best result from activated carbons derived from biomass. Therefore, this work put forward a nearly perfect solution which on one hand gets rid of environment-unfriendly algae residue while on the other hand produces high-quality activated carbon that is in return advantageous to environment protection.

  9. Adsorption of Zn(II) and Cd(II) ions onto magnesium and activated carbon composite in aqueous solution

    International Nuclear Information System (INIS)

    Magnesium and coconuts shell activated carbon composite was prepared to selectively remove heavy metals ions in aqueous solution. Zinc(II) and cadmium(II) ions were used to clarify the adsorption capacity of the composite in comparison with no magnesium containing activated carbon. Influence of the initial heavy metal concentration, time course and solution temperature on the adsorption amounts were examined for the two adsorbents, and surface chemistry of the adsorbents was also characterized using Boehm titration. The magnesium composite adsorbed greater amount of Zn(II) and Cd(II) ions than the no magnesium counterpart. The adsorption amount of Cd(II) was not influenced with rise in solution temperature for the composite, whereas decrease in adsorption was observed for the counterpart. The loaded magnesium was estimated to be combined with carbon surface via oxygen bridge. Cadmium(II) was adsorbed onto the composite surface by ion exchange process with releasing equivalent amount of Mg(II) from the carbon surface, while Zn(II) would adsorb onto the composite by not only the ion exchange, but also the electrostatic interaction with the Cπ electrons on the graphite surface from the experimental results.

  10. 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%.

  11. Oxydizing attack process of an uranium ore by a carbonated liquor

    International Nuclear Information System (INIS)

    Continuous process of oxydizing attack of an uranium ore with a recycled aqueous solution of alkaline carbonates and bicarbonates containing uranium compounds at a concentration near the solubility limit at the attack temperature and recovery of the precipitated uranium in the solid phase remaining after the attack

  12. 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...

  13. 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 ...

  14. Kinetics and Equilibrium Studies on Adsorption of Acid Red 18 (Azo-Dye) Using Multiwall Carbon Nanotubes (MWCNTs) from Aqueous Solution

    OpenAIRE

    Shirmardi, Mohammad; Mesdaghinia, Alireza; MAHVI, Amir Hossein; Nasseri, Simin; Nabizadeh, Ramin

    2012-01-01

    Azo dyes are one of the synthetic dyes that are used in many textile industries. Adsorption is one of the most effective techniques for removal of dye-contaminated wastewater. In this work, efficiency of multiwalled carbon nanotubes (MWCNTs) as an adsorbent for removal of Acid Red 18 (azo-dye) from aqueous solution was determined. The parameters affecting the adsorption process such as contact time, pH, adsorbent dosage, and initial dye concentration were studied. Experimental results have sh...

  15. 2, 4 dichlorophenol (2, 4-DCP) sorption from aqueous solution using granular activated carbon and polymeric adsorbents and studies on effect of temperature on activated carbon adsorption.

    Science.gov (United States)

    Ghatbandhe, A S; Yenkie, M K N

    2008-04-01

    Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenol (2,4-DCP), one of the most commonly used chlorophenol, onto bituminous coal based Filtrasorb-400 grade granular activated carbon, were studied in aqueous solution in a batch system with respect to temperature. Uptake capacity of activated carbon found to increase with temperature. Langmuir isotherm models were applied to experimental equilibrium data of 2, 4-DCP adsorption and competitive studies with respect to XAD resin were carried out. Equilibrium data fitted very well to the Langmuir equilibrium model. Adsorbent monolayer capacity 'Q0, Langmuir constant 'b' and adsorption rate constant 'k(a)' were evaluated at different temperatures for activated carbon adsorption. This data was then used to calculate the energy of activation of adsorption and also the thermodynamic parameters, namely the free energy of adsorption, deltaG0, enthalpy of adsorption, deltaH0 and the entropy of adsorption deltaS0. The obtained results showed that the monolayer capacity increases with the increase in temperatures. The obtained values of thermodynamic parameters showed that adsorption of 2,4 DCP is an endothermic process. Synthetic resin was not found efficient to adsorb 2,4 DCP compared to activated carbon. The order of adsorption efficiencies of three resins used in the study found as XAD7HP > XAD4 > XAD1180. PMID:19295102

  16. 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

  17. 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.

  18. Investigations on IR-spectroscopic process analysis of phosphate in aqueous solution

    International Nuclear Information System (INIS)

    This thesis is focusing on the development and optimization of a new analysis system for phosphate in aqueous solution based on FTIR-spectrometry. The investigation was aiming at an application in process analytical chemistry. Since the quality control of non-nutritive sweetened carbonated beverages (diet soft drinks) is still performed manually by means of the photometric molybdenum blue reaction, there is an industrial demand for an automated analysis system for phosphate in the concentration range of 200 to 600 mg/L. Because of technical and economic aspects the transferability of the method on a filter instrument is taken into further considerations. First experiments were concentrating on the stretching vibrations of the individual dissociation states of phosphate in the spectral region from 900 to 1200 cm-' and on their suitability for quantitative analysis. Finally, the reagent addition by means of an ion-exchange membrane (Nafion) was investigated. With that method it is principally possible to change the pH without any mechanical component. Although a good repeatability (3 mg/L) was obtained in phosphate standard solutions, it was not possible to achieve a conversion independent of the reagent (donor) flow rate. This would be achieved, if the conversion was close to equilibrium. However, this was not realized within a reasonable period of time. Summing up a new concept for measuring phosphate in aqueous solution by means of pH-modulation was developed, which largely fulfills the practical requirements concerning stability, reproducibility and precision of the flow system. Moreover the transferability to a simple filter instrument based on a single bandpass filter is achieved with the concept of an alternately changing pH. (author)

  19. Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Taha, Mohd F., E-mail: faisalt@petronas.com.my; Shaharun, Maizatul S. [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Perak Darul Ridzuan (Malaysia); Shuib, Anis Suhaila, E-mail: anisuha@petronas.com.my; Borhan, Azry [Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Perak Darul Ridzuan (Malaysia)

    2014-10-24

    An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m{sup 2}/g and 0.17 cm{sup 2}/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models.

  20. Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

    International Nuclear Information System (INIS)

    An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m2/g and 0.17 cm2/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models

  1. Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

    Science.gov (United States)

    Taha, Mohd F.; Shuib, Anis Suhaila; Shaharun, Maizatul S.; Borhan, Azry

    2014-10-01

    An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m2/g and 0.17 cm2/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models.

  2. 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

  3. Huygens Crater: Insights into Noachian Volcanism, Stratigraphy, and Aqueous Processes

    Science.gov (United States)

    Ackiss, S. E.; Wray, J. J.; Seelos, K. D.; Niles, P. B.

    2015-01-01

    Huygens crater is a well preserved peak ring structure on Mars centered at 13.5 deg S, 55.5 deg E in the Noachian highlands between Terras Tyrrhena and Sabaea near the NW rim of Hellas basin. With a diameter of approximately 470 km, it uplifted and exhumed pre-Noachian crustal materials from depths greater than 25 km, penetrating below the thick, ubiquitous layer of Hellas ejecta. In addition, Huygens served as a basin for subsequent aqueous activity, including erosion/deposition by fluvial valley networks and subsurface alteration that is now exposed by smaller impacts. Younger mafic-bearing plains that partially cover the basin floor and surrounding intercrater areas were likely emplaced by later volcanism.

  4. 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.

  5. A method for separating water soluble organics from a process stream by aqueous biphasic extraction

    Energy Technology Data Exchange (ETDEWEB)

    Chaiko, David J.; Mego, William A.

    1997-12-01

    The present invention relates to a method for separating water-miscible organic species from a process stream by aqueous biphasic extraction. In particular, the method includes extracting the organic species into a polymer-rich phase of an aqueous biphase system in which the process stream comprises the salt-rich phase, and, next, separating the polymer from the extracted organic species by contacting the loaded, polymer-rich phase with a water-immiscible organic phase. Alternatively, the polymer can be separated from the extracted organic species by raising the temperature of the loaded, polymer-rich phase above the cloud point, such that the polymer and the water-soluble organic species separate into two distinct aqueous phases. In either case, a substantially salt-free, concentrated aqueous solution containing the organic species is recovered.

  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. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Influence of bicarbonate and carbonate ions on sonochemical degradation of Rhodamine B in aqueous phase.

    Science.gov (United States)

    Merouani, Slimane; Hamdaoui, Oualid; Saoudi, Fethi; Chiha, Mahdi; Pétrier, Christian

    2010-03-15

    The influence of bicarbonate and carbonate ions on sonolytic degradation of cationic dye, Rhodamine B (RhB), in water was investigated. As a consequence of ultrasonic cavitation that generates .OH radicals, carbonate radicals were secondary products of water sonochemistry when it contains dissolved bicarbonate or carbonate ions. The results clearly demonstrated the significant intensification of sonolytic destruction of RhB in the presence of bicarbonate and carbonate, especially at lower dye concentrations. Degradation intensification occurs because carbonate radicals sonochemically formed undergo radical-radical recombination at a lesser extent than hydroxyl radicals. The generated carbonate radicals are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as RhB. Therefore, at low dye concentrations, carbonate radical presents a more selective reactivity towards RhB molecules than hydroxyl radical. In the presence of bicarbonate, degradation rate reached a maximum at 3 g L(-1) bicarbonate, but subsequent addition retards the destruction process. In RhB solutions containing carbonate, the oxidation rate gradually increased with increasing carbonate concentration up to 10 g L(-1) and slightly decreased afterward. Carbonate radicals sonochemically generated are suitable for total removal of COD of sonicated RhB solutions. PMID:19910116

  15. 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

  16. Humic Acid Degradation via Solar Photo-Fenton Process in Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Seyed Ali Sajjadi

    2015-08-01

    Full Text Available Control of mutagenic and carcinogenic disinfection by-products, particularly Trihalomethanes (THMs and Halo Acetic Acids (HAAs in water treatment process is critical, due to their adverse effects on human health. Generally, reducing the toxicity of these by-products hinges on prior removal of the precursor materials, such as Humic Acid (HA in drinking water. This study was conducted to investigate the role of some parameters that could affect the removal of HA, including HA (5 and 10 ppm and H2O2 (20, 40, 60, and 80 ppm initial concentrations, Iron (II, sulfate heptahydrate dosage (4, 8, 12, and 16 ppm, pH (2, 3, 4 and 5, Oxidation time (5, 10, 15 and 30 min, and Sunlight levels (322±13 kWm-2. To accelerate the process of HA removal, the Solar Photo-Fenton (SPF process was employed by direct irradiation of converged sunlight in a Parabolic Trough Collectors (PTC, with 3m2 effective area. HA levels were measured via quantifying Dissolved Organic Carbon (DOC concentrations by means of a TOC Analyzer method. The results showed that the SPF process is under control of the Fe & H2O2 ratio, the Fe2+ dosage and especially the pH quantity. In optimal condition, (pH: 4, oxidation time: 30min, initial HA levels: 50 ppm, H2O2 concentrations: 20 ppm Fe+2 levels: 4 ppm, the study found more than 98% DOC removal. In conclusion, the SPF, as an economically effective technique, could be applied for the removal of HA in aqueous environments.

  17. Composition and process for separating cesium ions from an acidic aqueous solution also containing other ions

    Science.gov (United States)

    Dietz, M.L.; Horwitz, E.P.; Bartsch, R.A.; Barrans, R.E. Jr.; Rausch, D.

    1999-03-30

    A crown ether cesium ion extractant is disclosed as is its synthesis. The crown ether cesium ion extractant is useful for the selective purification of cesium ions from aqueous acidic media, and more particularly useful for the isolation of radioactive cesium-137 from nuclear waste streams. Processes for isolating cesium ions from aqueous acidic media using the crown ether cesium extractant are disclosed as are processes for recycling the crown ether cesium extractant and processes for recovering cesium from a crown ether cesium extractant solution. 4 figs.

  18. Removal of methylene blue from aqueous solution with magnetite loaded multi-wall carbon nanotube: Kinetic, isotherm and mechanism analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Lunhong, E-mail: ah_aihong@163.com [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Shida Road 1, Nanchong 637002 (China); College of Chemistry and Chemical Engineering, China West Normal University, Shida Road 1, Nanchong 637002 (China); Zhang, Chunying [College of Chemistry and Chemical Engineering, China West Normal University, Shida Road 1, Nanchong 637002 (China); Liao, Fang; Wang, Yao [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Shida Road 1, Nanchong 637002 (China); College of Chemistry and Chemical Engineering, China West Normal University, Shida Road 1, Nanchong 637002 (China); Li, Ming; Meng, Lanying [College of Chemistry and Chemical Engineering, China West Normal University, Shida Road 1, Nanchong 637002 (China); Jiang, Jing [Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Shida Road 1, Nanchong 637002 (China); College of Chemistry and Chemical Engineering, China West Normal University, Shida Road 1, Nanchong 637002 (China)

    2011-12-30

    Highlights: Black-Right-Pointing-Pointer M-MWCNTs were synthesized by a facile one-pot solvothermal method and used as an efficient adsorbent for removing toxic dye from aqueous solution. Black-Right-Pointing-Pointer The adsorption process was characterized by kinetics and isotherm analysis. Black-Right-Pointing-Pointer FTIR analysis was employed to investigate the interactions between M-MWCNTs and dye. - Abstract: In this study, we have demonstrated the efficient removal of cationic dye, methylene blue (MB), from aqueous solution with the one-pot solvothermal synthesized magnetite-loaded multi-walled carbon nanotubes (M-MWCNTs). The as-prepared M-MWCNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The effects of contact time, initial dye concentration, and solution pH on the adsorption of MB onto M-MWCNTs were systematically studied. It was shown that the MB adsorption was pH-dependent. Adsorption kinetics was best described by the pseudo-second-order model. Equilibrium data were well fitted to the Langmuir isotherm model, yielding maximum monolayer adsorption capacity of 48.06 mg g{sup -1}. FTIR analysis suggested that the adsorption mechanism was possibly attributed to the electrostatic attraction and {pi}-{pi} stacking interactions between MWCNTs and MB.

  19. The process of dimethyl carbonate to diphenyl carbonate: thermodynamics, reaction kinetics and conceptual process design

    NARCIS (Netherlands)

    Haubrock, Jens

    2007-01-01

    Diphenyl carbonate (DPC) is a precursor in the production of Polycarbonate (PC), a widely employed engineering plastic. To overcome the drawbacks of the traditional PC process - e.g. phosgene as a reactant and methylene chloride as solvent- a new process route starting from Dimethyl carbonate (DMC)

  20. 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

  1. 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.

  2. 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.

  3. AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

    Energy Technology Data Exchange (ETDEWEB)

    K. Osseo-Asare; X. Zeng

    2001-06-30

    Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behaviors of hematite in the dextran (Dex)/Triton X-100 (TX100) and polyethylene glycol (PEG)/dextran systems were investigated and the effects of some ionic surfactants on solid partition were studied. In both biphase systems, the particles stayed in the bottom dextran-rich phase under all pH conditions. This behavior is attributable to the fact that the hydrophilic oxide particles prefer the more hydrophilic bottom phase. Also, the strong favorable interaction between dextran and ferric oxide facilitates the dispersion of the solids in the polysaccharide-rich phase. In the Dex/TX100 system, addition of sodium dodecylsulfate (SDS) or potassium oleate had no effect on the solid partition; on the other hand, addition of dodecyltrimethylammonium bromide (DTAB) transferred the particles to the top phase or interface at high pH values. In the PEG/Dex system, the preferred location of hematite remained the bottom phase in the presence of either SDS or DTAB. The effects of anionic surfactants on the partition behavior are attributable to the fact that they are not able to replace the strongly adsorbed polysaccharide layer on the ferric oxide surface. The results with the cationic surfactant are due to electrostatic interaction between the cationic surfactant and the charged surface of the solid particles. The difference in solids partitioning in the two systems is the result of the different distribution of DTAB in these systems. In the Dex/TX100 system, DTAB prefers the top surfactant-rich phase, while it concentrates in the bottom phase in the PEG/dextran system.

  4. 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.

  5. 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...

  6. ALKALINE CARBONATE LEACHING PROCESS FOR URANIUM EXTRACTION

    Science.gov (United States)

    Thunaes, A.; Brown, E.A.; Rabbitts, A.T.

    1957-11-12

    A process for the leaching of uranium from high carbonate ores is presented. According to the process, the ore is leached at a temperature of about 200 deg C and a pressure of about 200 p.s.i.g. with a solution containing alkali carbonate, alkali permanganate, and bicarbonate ion, the bicarbonate ion functionlng to prevent premature formation of alkali hydroxide and consequent precipitation of a diuranate. After the leaching is complete, the uranium present is recovered by precipitation with NaOH.

  7. Modelling of the aqueous debittering process of Lupinus mutabilis Sweet

    NARCIS (Netherlands)

    Carvajal-Larenas, F.E.; Nout, M.J.R.; Boekel, van M.A.J.S.; Linnemann, A.R.

    2013-01-01

    We investigated the process of lupin debittering by soaking, cooking and washing in water using a newly designed hydroagitator. The effect on alkaloids content, solids in the product, final weight, processing time and water and energy consumption were expressed in a mathematical model for optimizati

  8. AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

    Energy Technology Data Exchange (ETDEWEB)

    K. Osseo-Asare; X. Zeng

    2001-06-30

    Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behaviors of silica in the polyethylene glycol (PEG)/dextran (Dex) and dextran/Triton X-100 (TX100) systems have been investigated, and the effects of sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) on solid partition have been studied. In both biphase systems, silica particles stayed in the top PEG-rich phase at low pH. With increase in pH, the particles moved from the top phase to the interface, then to the bottom phase. At very high pH, the solids preferred the top phase again. These trends are attributable to variations in the polymer/solid and nonionic surfactant/solid interactions. Addition of ionic surfactants into these two systems introduces a weakly charged environment, since ionic surfactants concentrate into one phase, either the top phase or the bottom phase. Therefore, coulombic forces also play a key role in the partition of silica particles because electrostatic attractive or repulsive forces are produced between the solid surface and the ionic-surfactant-concentrated phase. For the PEG/dextran system in the presence of SDS, SiO{sub 2} preferred the bottom dextran-rich phase above its pH{sub PZC}. However, addition of DTAB moved the oxide particles from the top phase to the interface, and then to the bottom phase, with increase in pH. These different behaviors are attributable to the fact that SDS and DTAB concentrated into the opposite phase of the PEG/dextran system. On the other hand, in the dextran/Triton X-100 system, both ionic surfactants concentrated in the top surfactant-rich phase and formed mixed micelles with TX100. Therefore, addition of the anionic surfactant, SDS, moved the silica particles from top phase to the

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. Organic-aqueous crossover coating process for the desmopressin orally disintegrating microparticles.

    Science.gov (United States)

    Kim, Ju-Young; Hwang, Kyu-Mok; Park, Chun-Woong; Rhee, Yun-Seok; Park, Eun-Seok

    2015-02-01

    The purpose of the present study was to prepare desmopressin orally disintegrating microparticles (ODMs) using organic-aqueous crossover coating process which featured an organic sub-coating followed by an aqueous active coating. Sucrose beads and hydroxypropyl cellulose (HPC) were used as inert cores and a coating material, respectively. Characterizations including size distribution analysis, in-vitro release studies and in-vitro disintegration studies were performed. A pharmacokinetic study of the ODMs was also conducted in eight beagle dogs. It was found that sucrose beads should be coated using organic solvents to preserve their original morphology. For the active coating, the aqueous coating solution should be used for drug stability. When sucrose beads were coated using organic-aqueous crossover coating process, double-layer ODMs with round shapes were produced with detectable impurities below limit of US Pharmacopeia. The median size of ODMs was 195.6 μm, which was considered small enough for a good mouthfeel. The ODMs dissolved in artificial saliva within 15 s because of hydrophilic materials including sucrose and HPC in the ODMs. Because of its fast-dissolving properties, 100% release of the drug was reached within 5 min. Pharmacokinetic parameters including Cmax and AUC24 indicated bioequivalence of the ODMs and the conventional immediate release tablets. Therefore, by using the organic-aqueous crossover coating process, double-layer ODMs were successively prepared with small size, round shapes and good drug stability. PMID:24252109

  15. 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.

  16. 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.

  17. Evolution of Sustainable Carbon Cycling Processes in China

    Institute of Scientific and Technical Information of China (English)

    Zhuang Yahui; Zhang Hongxun; Wang Xiaoke; Fang Jinyun

    2004-01-01

    This report summarizes the surveys on carbon inventories and initiatives on sustainable carbon cycling taken by RCEES. The first part of this report deals with the concept of sustainable carbon cycling, the historical evolution of carbon cycling processes in China, carbon pool enhancement, value addition, carbon sequestration and carbon balance.The second part covers the modeling of carbon dynamics, emission inventories of various carboncontaining greenhouse gases and their potential abatement measures.

  18. Aqueous Processes for Dyeing Generic, Unmodified Polypropylene Fiber

    Directory of Open Access Journals (Sweden)

    Murari L. Gupta

    2010-06-01

    Full Text Available Acid leuco vat dyeings of polypropylene (PP fabrics in combinations of a trichromatic series of colorants (red, yellow and blue plus an orange were performed in order to determine the compatibility of the component colorants in the developed single stage, batch exhaust dyeing process reported earlier. Cross-section micrographs of dyed fibers revealed the absence of "ring-dyeing". Tensile tests and X-ray crystallinity results confirmed that the developed dyeing process did not significantly alter the tensile strength and modulus of the dyed PP textiles. PP fabrics dyed with simulated, continuous acid vat dyeing processes (pad-steam and pad-dry heat demonstrated good color yields and levelness with adequate fastness to crocking, washing and dry cleaning.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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)

  5. 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.

  6. 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....

  7. 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.

  8. 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.

  9. 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

  10. 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)

  11. Guidelines for the scale-up of an aqueous ceramic process: a case study of statistical process control

    OpenAIRE

    Mortara, L; Alcock, Jeffrey R.

    2011-01-01

    Process-scale up is the change from a feasibility study in a laboratory to a full-scale prototype production process. It is an important issue for the ceramics industry, but has been the subject of relatively little systematic research. This paper will show how certain manufacturing concepts used in a number of industries - can be applied to the scale up of a feasibility study level, aqueous tape casting process. In particular, it examines the elements of process standardisa...

  12. 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...

  13. New Carbon Activation Process for Increased Surface Accessibility in Electrochemical Capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    1999-03-16

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm{sup 3} is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350 C for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  14. Novel graphene production: an aqueous arc discharge process

    OpenAIRE

    Kim, Sejung

    2015-01-01

    Graphene plays important roles in technological developments regarding electronic device, environment and energy management and the motivation to prepare two-dimensional (2D) nanomaterials. As the pioneer for 2D nanomaterials, graphene has been shown to be not only thermodynamically stable, but also superior in terms of electronic and mechanical properties and that it can be processed into a wide variety of novel materials. However, they are still limited to the challenges such as multi-stack...

  15. Study of the processes of carbonization and oxidation of porous silicon by Raman and IR spectroscopy

    International Nuclear Information System (INIS)

    Porous silicon layers were produced by electrochemical etching of single-crystal silicon wafers with the resistivity 10 Ω cm in the aqueous-alcohol solution of hydrofluoric acid. Raman spectroscopy and infrared absorption spectroscopy are used to study the processes of interaction of porous silicon with undiluted acetylene at low temperatures and the processes of oxidation of carbonized porous silicon by water vapors. It is established that, even at the temperature 550°C, the silicon-carbon bonds are formed at the pore surface and the graphite-like carbon condensate emerges. It is shown that the carbon condensate inhibits oxidation of porous silicon by water vapors and contributes to quenching of white photoluminescence in the oxidized carbonized porous silicon nanocomposite layer.

  16. Effects of process parameters on hydrothermal carbonization

    Science.gov (United States)

    Uddin, Md. Helal

    In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

  17. Feasibility study of a solar reactor for phenol treatment by the Photo-Fenton process in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, K.R.B.; Nascimento, C.A.O.; Guardani, R.; Teixeira, A.C.S.C. [University of Sao Paulo, Chemical Engineering Department, Sao Paulo (Brazil)

    2012-12-15

    Solar reactors can be attractive in photodegradation processes due to lower electrical energy demand. The performance of a solar reactor for two flow configurations, i.e., plug flow and mixed flow, is compared based on experimental results with a pilot-scale solar reactor. Aqueous solutions of phenol were used as a model for industrial wastewater containing organic contaminants. Batch experiments were carried out under clear sky, resulting in removal rates in the range of 96-100 %. The dissolved organic carbon removal rate was simulated by an empirical model based on neural networks, which was adjusted to the experimental data, resulting in a correlation coefficient of 0.9856. This approach enabled to estimate effects of process variables which could not be evaluated from the experiments. Simulations with different reactor configurations indicated relevant aspects for the design of solar reactors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Alkaline carbonates in blast furnace process

    Directory of Open Access Journals (Sweden)

    P. Besta

    2014-10-01

    Full Text Available The production of iron in blast furnaces is a complex of physical, chemical and mechanical processes. The input raw materials contain not only metallic components, but also a number of negative elements. The most important negative elements include alkaline carbonates. They can significantly affect the course of the blast furnace process and thus the overall performance of the furnace. As a result of that, it is essential to accurately monitor the alkali content in the blast furnace raw materials. The article analyzes the alkali content in input and output raw materials and their impact on the blast furnace process.

  19. 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.

  20. 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.

  1. Soret diffusion processes in aqueous sodium chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, R.T.

    1985-01-01

    The mass transport of chemical species induced by a temperature gradient, commonly known as Soret diffusion, has been examined for the case of the sodium chloride and water system. The occurrence of significant thermal gradients in geological media, especially those associated with radioactive waste disposal sites, can produce a measurable flux of sodium chloride and therefore enrich the local solutions. Soret coefficients, or the ratio of thermal to isothermal mass transport factors, describe this rate of mass transfer and are necessary for evaluating certain nonequilibrium processes, such as the migration of fluid inclusions in rock salt. Experimental Soret coefficients for the NaCl-H/sub 2/O system were obtained by the use of a conductimetric thermal diffusion cell. This approach relies on monitoring the electrical conductivity change of two separate isothermal reservoirs which are maintained at different temperatures. The Soret cell is situated between the reservoirs and is comprised of an inert matrix of glass beads in order to minimize any solution convection. The utilization of this porous medium requires corrections for porosity and tortuosity. Measurements were made for 0.1 and 1.0 N NaCl solutions at mean temperatures of 40/sup 0/C and 50/sup 0/C with the mass transport induced by a thermal gradient of 2.6/sup 0/C/cm. The preliminary results indicate a Soret separation on the order of 1 to 2 percent with the attainment of a steady state in approximately 15 hours.

  2. Process for recovering pertechnetate ions from an aqueous solution also containing other ions

    Science.gov (United States)

    Rogers, R.; Horwitz, E.P.; Bond, A.H.

    1997-02-18

    A solid/liquid process for the separation and recovery of TcO{sub 4}{sup {minus}1} ions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups; whereas the aqueous solution from which the TcO{sub 4}{sup {minus}1} ions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt. A solid/liquid phase admixture of separation particles containing bound TcO{sub 4}{sup {minus}1} ions in such an aqueous solution that is free from MoO{sub 4}{sup {minus}2} ions is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture. 15 figs.

  3. Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids: Implications for Geologic Carbon Sequestration

    Science.gov (United States)

    Miller, Q. R.; Schaef, T.; Thompson, C.; Loring, J. S.; Windisch, C. F.; Bowden, M. E.; Arey, B. W.; McGrail, P.

    2012-12-01

    Global climate change is viewed by many as an anthropogenic phenomenon that could be mitigated through a combination of conservation efforts, alternative energy sources, and the development of technologies capable of reducing carbon dioxide (CO2) emissions. Continued increases of atmospheric CO2 concentrations are projected over the next decade, due to developing nations and growing populations. One economically favorable option for managing CO2 involves subsurface storage in deep basalt formations. The silicate minerals and glassy mesostasis basalt components act as metal cation sources, reacting with the CO2 to form carbonate minerals. Most prior work on mineral reactivity in geologic carbon sequestration settings involves only aqueous dominated reactions. However, in most sequestration scenarios, injected CO2 will reside as a buoyant fluid in contact with the sealing formation (caprock) and slowly become water bearing. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet scCO2. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably wet supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) in order to gain insight into reaction processes. Mineral transformation reactions were followed by two novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the scCO2 resulted in increased carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared (IR) spectroscopy and indirectly with 18O isotopic labeling techniques (Raman spectroscopy). The thin water films were determined to be critical for facilitating carbonation processes in wet scCO2. Even in extreme low water conditions, the IR technique detected the formation of

  4. 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.

  5. A non-aqueous reduction process for purifying 153Gd produced in natural europium targets

    International Nuclear Information System (INIS)

    Gadolinium-153 is a low-energy gamma-emitter used in nuclear medicine imaging quality assurance. Produced in nuclear reactors using natural Eu2O3 targets, 153Gd is radiochemically separated from europium isotopes by europium reduction. However, conventional aqueous europium reduction produces hydrogen gas, a flammability hazard in radiological hot cells. We altered the traditional reduction method, using methanol as the process solvent to nearly eliminate hydrogen gas production. This new, non-aqueous reduction process demonstrates greater than 98% europium removal and gadolinium yields of 90%. - Highlights: • 153Gd typically separated from natural Eu reactor targets by aqueous Eu reduction. • Conventional aqueous Eu reduction produces H2, a flammability hazard in hot cells. • New reduction method uses methanol as process solvent, H2 nearly eliminated. • Bench top results show a two-pass Eu reduction by a factor of 1600, 91% 153Gd yield. • Hot cell results show a one-pass removal of >98% Eu and 90% 153Gd yield

  6. 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...

  7. Preparation of activated carbon from a renewable bio-plant of Euphorbia rigida by H 2SO 4 activation and its adsorption behavior in aqueous solutions

    Science.gov (United States)

    Gerçel, Özgül; Özcan, Adnan; Özcan, A. Safa; Gerçel, H. Ferdi

    2007-03-01

    The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H 2SO 4. The surface area of chemically modified activated carbon was 741.2 m 2 g -1. The surface characterization of both plant- and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g -1 at 40° C. The adsorption kinetics of methylene blue obeys the pseudo-second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as Δ G°, Δ H° and Δ S° were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.51 kJ mol -1. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes.

  8. REMOVAL OF REMAZOL ROSSO RB DYE FROM AQUEOUS EFFLUENTS BY HOMOGENOUS FENTON OXIDATION PROCESSES

    OpenAIRE

    Carmen Zaharia; Victoria Fedorcea; Adrian Beda; Victor Amarandei; Augustin Muresan

    2014-01-01

    The paper presents some data from our laboratory-setup experiments of homogenous oxidative processes with hydrogen peroxide (i.e. advanced Fenton oxidation processes) applied for Remazol Rosso RB dye-containing aqueous systems, especially textile effluents. Therefore, some different operating parameters (including pH, concentration of dye, H2O2 and ferrous ions, oxidation time, temperature, stirring regime, among its) were tested for determination of the best performance in effluent decolorat...

  9. Comparison efficiency of both sonochemical and sonochemical/hydrogen peroxide processes forcyanide removal from aqueous solutions

    OpenAIRE

    Reza Shokohi; Amir Hossein Mahvi; Ziaeddin Bonyadi

    2009-01-01

    (Received 5 October, 2009 ; Accepted 23 December, 2009)AbstractBackground and purpose: Cyanide is a species of high toxicity that is found mostly in industrial effluents such as electroplating, metal mining, metallurgy and metal cleaning processes. Entrance of it to existing environment contains a hazardous to health. The purpose of this study was to compare efficiency of both sonochemical and sonochemical / hydrogen peroxide processes for cyanide removal from aqueous solutions.Materials and ...

  10. 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.

  11. Carbon Nanotube Integration with a CMOS Process

    Science.gov (United States)

    Perez, Maximiliano S.; Lerner, Betiana; Resasco, Daniel E.; Pareja Obregon, Pablo D.; Julian, Pedro M.; Mandolesi, Pablo S.; Buffa, Fabian A.; Boselli, Alfredo; Lamagna, Alberto

    2010-01-01

    This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. PMID:22319330

  12. Carbon Nanotube Integration with a CMOS Process

    Directory of Open Access Journals (Sweden)

    Maximiliano S. Perez

    2010-04-01

    Full Text Available This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture.

  13. One-pot synthesis and control of aqueous soluble and organic soluble carbon dots from a designable waterborne polyurethane emulsion

    Science.gov (United States)

    Gu, Jiangjiang; Hu, Donghua; Huang, Jin; Huang, Xin; Zhang, Qiuhong; Jia, Xudong; Xi, Kai

    2016-02-01

    Carbon dots (CDs) have a wide range of applications and have drawn great interest in the recent decade. The fabrication and control of CDs with different solubilities are still urgent problems for their practical use. In this paper, aqueous soluble and organic soluble CDs (ACDs, OCDs) were produced by one-pot hydrothermal treatment of a designable waterborne polyurethane (WPU) emulsion. The difference in the solubility and fluorescence of these two kinds of CDs was attributed to the various functional groups on the surface, which were derived from the different segment fragments formed by hydrothermal treatment of a block polymer. It was found that the yields of the ACDs and OCDs could be regulated by means of selecting different soft segments in WPU. The more hydrophobic soft segments could result in an increase of the OCDs and a decrease of the ACDs. While the soft segments were hydrophilic or hydrolysable under hydrothermal conditions, only ACDs were obtained. The ACDs had good fluorescence and showed low cytotoxicity for use in multicolour bio-imaging. The OCDs processed good solubility in a wide range of organic solvents and were suitable for preparing fluorescent composite films with polymers.Carbon dots (CDs) have a wide range of applications and have drawn great interest in the recent decade. The fabrication and control of CDs with different solubilities are still urgent problems for their practical use. In this paper, aqueous soluble and organic soluble CDs (ACDs, OCDs) were produced by one-pot hydrothermal treatment of a designable waterborne polyurethane (WPU) emulsion. The difference in the solubility and fluorescence of these two kinds of CDs was attributed to the various functional groups on the surface, which were derived from the different segment fragments formed by hydrothermal treatment of a block polymer. It was found that the yields of the ACDs and OCDs could be regulated by means of selecting different soft segments in WPU. The more

  14. Solution processed large area field effect transistors from dielectrophoreticly aligned arrays of carbon nanotubes

    OpenAIRE

    Stokes, Paul; Silbar, Eliot; Zayas, Yashira M.; Khondaker, Saiful I.

    2008-01-01

    We demonstrate solution processable large area field effect transistors (FETs) from aligned arrays of carbon nanotubes (CNTs). Commercially available, surfactant free CNTs suspended in aqueous solution were aligned between source and drain electrodes using ac dielectrophoresis technique. After removing the metallic nanotubes using electrical breakdown, the devices displayed p-type behavior with on-off ratios up to ~ 2X10^4. The measured field effect mobilities are as high as 123 cm2/Vs, which...

  15. 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

  16. 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.

  17. Study of aqueous process using hydrochloric acid for radioactive waste including uranium

    International Nuclear Information System (INIS)

    A lot of solid and liquid radioactive wastes had been produced in the various examinations. The wastes have been stored in Japan Nuclear Cycle Development Institute Ningyo-Toge Environmental Engineering Center. Amounts of solid wastes including fluorine and uranium are very much, so techniques of final disposal will be developed and the solid wastes will be disposed. This study estimates the applicability of aqueous process using hydrochloric acid for CaF2, NaF, Al2O3 and UF4, so examinations using those wastes were performed and mass balance and activity balance sheets were made. The conclusion is as below. 1. The process using hydrochloric acid to CaF2 is applicable. 2. The process using hydrochloric acid to NaF is applicable. 3. Dissolution of Al2O3 is difficult, but uranium in Al2O3 is almost dissolved, so application of aqueous process using hydrochloric acid for Al2O3 is possible. 4. Application of aqueous process using hydrochloric acid to UF4 has problem of insolubility of UF4. 5. Next subjects are a rise of solid/liquid ratio, a increase of efficiency of uranium precipitation and decrease of second wastes which are resins and aluminium as masking material to fluorine. (author)

  18. Preparation, characterization and adsorption properties of chitosan modified magnetic graphitized multi-walled carbon nanotubes for highly effective removal of a carcinogenic dye from aqueous solution

    International Nuclear Information System (INIS)

    Novel chitosan-modified magnetic graphitized multi-walled carbon nanotubes (CS-m-GMCNTs) were synthesized via a suspension cross-linking method. Composition, morphology and magnetic properties of as-prepared CS-m-GMCNTs were characterized by XRD, SEM-EDS, BET and VSM. The large saturation magnetization (12.27 emu g−1) allows fast separation of CS-m-GMCNTs from treated aqueous solution. The adsorption of congo red (CR) on CS-m-GMCNTs was strongly dependent on pH, temperature of the aqueous phase and adsorbent dosage. Up to 100 and 94.58% color removal could be achieved in 100 min contact time with 10 and 50 mg L−1 of initial concentrations, respectively. The adsorption capacity of CR onto CS-m-GMCNTs could reach 262.9 mg g−1. The pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.999) was suitable to describe the process of CR adsorption onto CS-m-GMCNTs. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model. Values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process was strongly dependent on temperature of the aqueous phase, and spontaneous and endothermic process in nature. Therefore, CS-m-GMCNTs adsorbent displays main advantages of excellent dispersion, convenience separation and high adsorption capacity, which implies their potential application in the environmental cleanup.

  19. Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents

    International Nuclear Information System (INIS)

    Highlights: • Microwave-assisted cocoa shell activated carbon was prepared and characterized. • The anti-inflammatories, diclofenac and nimesulide, were adsorbed onto MWCS-1.0. • Adsorption maximum values are 63.47 (diclofenac) and 74.81 mg g−1 (nimesulide). • General order kinetic model suitably explained the adsorption process. • MWCS-1.0 was effectively used for treatment of simulated hospital effluents. - Abstract: Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L−1 HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N2 adsorption/desorption curves, X-ray diffraction, and point of zero charge (pHpzc). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g−1, respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations

  20. Switching to carbon-free production processes: Implications for carbon leakage and border carbon adjustment

    International Nuclear Information System (INIS)

    Climate policy under partial global compliance raises concerns regarding carbon leakage. While border carbon adjustment (BCA) measures are a potential remedy, they have also been criticised on various grounds. This paper therefore investigates whether a policy fostering the switch to carbon-free technologies can substitute for BCAs. A reason for the effectiveness of a targeted technology policy is that major leakage prone sectors (such as iron and steel), have two main sources of carbon emissions, combustion of fossil fuels and industrial processes. While combustion emissions can be reduced relatively easy by increasing energy efficiency, reducing process emissions requires a switch to low-carbon production processes, e.g. in steel production by deploying electrolysis based on large-scale solar electricity. We show by means of a multi-regional computable general equilibrium analysis that such a switch in steel production technology can eliminate a significant fraction of carbon leakage and also increase sectoral output and welfare. Since the necessary technologies are not available at large scale yet (however, are likely to be by 2020), a transitional BCA scheme may be a crucial supportive instrument to foster such technology switches. Yet, in the long run BCA should be phased out to preserve the incentive for carbon-free innovation. - Highlights: • A carbon-free technology switch in iron production considerably reduces total leakage. • Border carbon adjustment (BCA) may impede domestic industrial decarbonisation. • A targeted technology policy is superior to BCA in fostering low-carbon investments. • But implemented as a transitory instrument, BCA reinforces technology policy

  1. 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

  2. Adsorption of uranium from aqueous solutions using activated carbon prepared from olive stones

    International Nuclear Information System (INIS)

    Full text: Separation and purification processes based on adsorption technique are 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 [1]. Activated carbons are unique adsorbents because of their extended surface area, microporous structure, high adsorption capacity and high degree of surface reactivity [2]. Aegean Region of Turkey is famous with olive trees. Therefore, there are considerable amount of olive stones as an agricultural by-product. Activated carbon can be produced by using every kind of carbonaceous material including agricultural by-products. Taking into consideration of its importance as an agricultural by-product, it can be widely used as a precursor for the preparation of activated carbon. The activated carbons used in this study were prepared by the chemical activation of olive stone. Adsorption experiments were carried out by a batch technique. Before and after adsorption, the concentration of uranium was determined by the ICP-OES. In this study 1:2 precursor/activating agent (ZnCl2) ratio and 600oC carbonization temperature were used for the preparation of adsorbent. The adsorption of uranium was studied as a function of shaking time, pH, initial uranium concentration and temperature. The optimum conditions were found as 5 minutes shaking time, pH 6, 25 ppm uranium concentration, and 30oC temperature. The results suggest that uranium is favorably adsorbed by activated carbon prepared from olive stones. We are of the opinion that the method can be used for preventing environmental contamination and adsorption of uranium from wastes in various stages of nuclear fuel production depending on uranium fuel cycle

  3. Caracterización del proceso de adsorción de 3-cloro fenol desde solución acuosa sobre carbon activado por calorimetria de inmersión Characterization of 3-chlorophenol adsorption process from aqueous solution on activated carbon by immersion calorimetry

    Directory of Open Access Journals (Sweden)

    Liliana Giraldo

    2009-01-01

    Full Text Available The immersion enthalpy of activated carbon in 3-chlorophenol solutions, of 100 mg L-1, is determined at different pH values between 3 and 11 with results between 37.6 and 21.2 J g-1. The 3-chlorophenol adsorbed quantities on the activated carbon during the calorimetric experience, are between 1.13 and 2.19 mg g-1, for different pH values of the solution. The 3-chlorophenol adsorbed quantity and the immersion enthalpy decrease by increasing of the pH solution, while increasing the adsorbed quantity increases the immersion enthalpy value.

  4. 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

  5. Friction stir processing on carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Sergei Yu., E-mail: tsy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055, Russia and National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Melnikov, Alexander G., E-mail: melnikov-ag@tpu.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Rubtsov, Valery E., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2014-11-14

    Friction stir processing of medium carbon steel samples has been carried out using a milling machine and tools made of cemented tungsten carbide. Samples have been machined from 40 and 40X steels. The tools have been made in the shape of 5×5×1.5 mm and 3×3×1.5 mm tetrahedrons. The microstructure of stirred zone has been obtained using the smaller tool and consists of fine recrystallized 2-3 μm grains, whereas the larger tool has produced the 'onion-like' structures comprising hard quenched 'white' 500-600 MPa layers with 300-350 MPa interlayers of bainite needles. The mean values of wear intensity obtained after measuring the wear scar width were 0.02 mm/m and 0.001 mm/m for non-processed and processed samples, respectively.

  6. Friction stir processing on carbon steel

    International Nuclear Information System (INIS)

    Friction stir processing of medium carbon steel samples has been carried out using a milling machine and tools made of cemented tungsten carbide. Samples have been machined from 40 and 40X steels. The tools have been made in the shape of 5×5×1.5 mm and 3×3×1.5 mm tetrahedrons. The microstructure of stirred zone has been obtained using the smaller tool and consists of fine recrystallized 2-3 μm grains, whereas the larger tool has produced the 'onion-like' structures comprising hard quenched 'white' 500-600 MPa layers with 300-350 MPa interlayers of bainite needles. The mean values of wear intensity obtained after measuring the wear scar width were 0.02 mm/m and 0.001 mm/m for non-processed and processed samples, respectively

  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. 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.

  11. 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%.

  12. 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.

  13. 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.)

  14. 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

  15. 炭材料对铀的吸附%Adsorption of Uranium by Carbon Materials from Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    李兴亮; 宋强; 刘碧君; 刘春霞; 王航; 耿俊霞; 陈震; 刘宁; 李首建

    2011-01-01

    Uranium is both the major constituent of nuclear fuel and one of the key nuclides in spent fuel reprocessing.Separation of uranium in various aqueous effluent streams via adsorption or solid-phase extraction can not only recycle this precious resource,but also reduce the cost for the final disposal of radioactive wastes.Carbon based sorbents,at least potentially,should play a correspondingly important role for this purpose.Carbon materials were chosen as the adsorbing material because of their large specific surface area,better acid and alkaline stability and higher radiation and thermal resistance.The adsorption capacity of carbon materials can be improved by surface oxidization and other chemical or physical modifications,such as impregnating,coating,or grafting functional molecules or groups that can extract uranium selectively from liquid solution.Comparing with other modification methods,grafting technology is a promising method because of its excellent affinity and high selectivity.Uranium in aqueous wastes can be effectively removed by electrosorption onto electrode made of carbon fibers.It seems that electrosorption process for the removal of uranium has a prospect of industrialization because of the high electrosorption efficiency and the low-cost regeneration of carbon fiber electrode.%铀既是核燃料的主要成分又是乏燃料后处理的关键核素。将铀从乏燃料后处理流程中的高放射性料液或者其他含铀废水中分离出来既可以将此宝贵的核燃料回收使用,又有利于降低乏燃料处理后期的处置费用以及减少铀对环境的污染。而从海水、盐湖水、尾矿废水等贫铀水体中提取铀则可能是解决将来铀资源匮乏的主要方法。炭质材料具有较大的比表面积、较高的孔隙率,耐高温,抗辐射,对各种酸碱环境有很高稳定性,而且本身无毒,环境友好,有望作为吸附剂或固相萃取材料用于从水体中吸附分离铀。本文介绍了活

  16. 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.

  17. High-performance magnetic carbon materials in dye removal from aqueous solutions

    Science.gov (United States)

    Gao, Xiaoming; Zhang, Yu; Dai, Yuan; Fu, Feng

    2016-07-01

    To obtain a novel adsorbent with excellent adsorption capacity and convenient magnetic separation property, magnetic activated semi-coke was prepared by KOH activation method and further modified by FeCl3. The surface morphology, physical structure, chemical properties and textural characteristics of unmodified semi-coke, KOH-modified semi-coke and magnetic activated semi-coke were characterized by scanning electron microscopy, X-ray powder diffraction, N2 adsorption-desorption measurement, and electronic differential system. The adsorption characteristics of the magnetic activated semi-coke were explored for the removal of methyl orang (MO), methylene blue (MB), congo red (CR), acid fuchsin (AF), and rhodamine B (RB) from aqueous solution. The effects of adsorption parameters, including adsorbent dosage, pH and contact time, were investigated by comparing the adsorption properties of the magnetic activated semi-coke to RB. The result showed that the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. The adsorption experiment data indicated that the pseudosecond order model and the Langmuir model could well explain the adsorption processes of RB on the magnetic activated semi-coke, and the maximum adsorption capacity (qm) was 526.32 mg/g. The values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process depended on the temperature of the aqueous phase, and it was spontaneous and exothermic in nature. As the addition of the magnetic activated semi-coke, the color of the solution significantly faded. Subsequently, fast aggregation of the magnetic activated semi-coke from their homogeneous dispersion in the presence of an external magnetic field could be happened. So, the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity.

  18. A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

    OpenAIRE

    Nan Sun; Bin Li,; Jianping Shao; Weimin Mo; Baoxiang Hu; Zhenlu Shen; Xinquan Hu

    2012-01-01

    A general and facile one-pot protocol for the preparation of a broad range of alkyl and aryl isothiocyanates has been developed from their corresponding primary amines under aqueous conditions. This synthetic process involves an in situ generation of a dithiocarbamate salt from the amine substrate by reacting with CS2 followed by elimination to form the isothiocyanate product with cyanuric acid as the desulfurylation reagent. The choice of solvent is of decisive importance for the successful ...

  19. Removal of 4-nitrophenol from aqueous solution by adsorption onto activated carbon prepared from Acacia glauca sawdust.

    Science.gov (United States)

    Dhorabe, Prashant T; Lataye, Dilip H; Ingole, Ramakant S

    2016-01-01

    The present paper deals with a complete batch adsorption study of 4-nitrophenol (4NP) from aqueous solution onto activated carbon prepared from Acacia glauca sawdust (AGAC). The surface area of the adsorbent determined by methylene blue method is found to be 311.20 m(2)/g. The optimum dose of adsorbent was found to be 2 g/l with 4NP uptake of 25.93 mg/g. The equilibrium time was found to be 30 minutes with the percentage removal of 96.40 at the initial concentration of 50 ppm. The maximum removal of 98.94% was found to be at pH of 6. The equilibrium and kinetic study revealed that the Radke-Prausnitz isotherm and pseudo second order kinetics model fitted the respective data well. In the thermodynamic study, the negative value of Gibbs free energy change (-26.38 kJ/mol at 30°C) and enthalpy change (-6.12 kJ/mol) showed the spontaneous and exothermic nature of the adsorption process. PMID:26901740

  20. Optimized removal of antibiotic drugs from aqueous solutions using single, double and multi-walled carbon nanotubes.

    Science.gov (United States)

    Ncibi, Mohamed Chaker; Sillanpää, Mika

    2015-11-15

    In this study, experiments were carried out to investigate the use of as-synthesized single-walled (SWCNT), double-walled (DWCNT) and multi-walled carbon nanotubes (MWCNT) agglomerates for the removal of two antibiotics, Oxytetracycline (OXY) and Ciprofloxacin (CIP) from aqueous solution. The variations of key operating parameters on the removal process were assessed in order to find out the optimum conditions. It includes exposure time, solution pH, temperature, ultrasound assistance and desorption assays. The experimental results revealed that a moderate increase in adsorption was registered between pH 3 and 7 for both antibiotics. The application of ultrasound helped enhancing the removal capacities of OXY for all tested CNTs. For the case of MWCNTs, 1h of ultrasonication increased the adsorption capacity by 44.6%. As for CIP, the ultrasonic treatment did not enhance the overall adsorption, especially for the case of DWCNTS. The Brouers-Sotolongo equation was the best fitting isotherm model. The highest removal capacities were registered using SWCNTS for both antibiotics (724 mg/g for CIP and 554 mg/g for OXY). In addition, ethanol was the solvent that induced the highest desorption percent for the case of CIP (52% for MWCNTs). However, the desorption of OXY was negligible for all solvents (maximum 3.3% for DWCNTs using ethanol). PMID:26024613

  1. Effectiveness of Quercus Branti Activated Carbon in Removal of Methylene Blue from Aqueous Solutions

    OpenAIRE

    Abdolmotaleb Seidmohammadi; Ghorban Asgari; Mostafa Leili; Abdollah Dargahi; Azam Mobarakian

    2015-01-01

    Background & Aims of the Study: Dyes are one of the most contaminants in textile industrial wastewater that they are often carcinogenic, mutagenic and non-degradable. Therefore, with regard to environmental aspects, their removal from effluents is very essential. The purpose of this study was the perception of adsorption process and promotion of an economic technology for colored wastewater treatment. Therefore, activated carbon from Oak fruit bark was used as an effective and economic adsorb...

  2. 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...

  3. NOCHAR Polymers: An Aqueous and Organic Liquid Solidification Process for Cadarache LOR (Liquides Organiques Radioactifs) - 13195

    International Nuclear Information System (INIS)

    To handle the Very Low Level Waste (VLLW) and the Low Level Waste (LLW) in France, two options can be considered: the incineration at CENTRACO facility and the disposal facility on ANDRA sites. The waste acceptance in these radwaste routes is dependent upon the adequacy between the waste characteristics (physical chemistry and radiological) and the radwaste route specifications. If the waste characteristics are incompatible with the radwaste route specifications (presence of significant quantities of chlorine, fluorine, organic component etc or/and high activity limits), it is necessary to find an alternative solution that consists of a waste pre-treatment process. In the context of the problematic Cadarache LOR (Liquides Organiques Radioactifs) waste streams, two radioactive scintillation cocktails have to be treated. The first one is composed of organic liquids at 13.1 % (diphenyloxazol, mesitylene, TBP, xylene) and water at 86.9 %. The second one is composed of TBP at 8.6 % and water at 91.4 %. They contain chlorine, fluorine and sulphate and have got alpha/beta/gamma spectra with mass activities equal to some kBq.g-1. Therefore, tritium is present and creates the second problematic waste stream. As a consequence, in order for disposal acceptance at the ANDRA site, it is necessary to pre-treat the waste. The NOCHAR polymers as an aqueous and organic liquid solidification process seem to be an adequate solution. Indeed, these polymers constitute an important variety of products applied to the treatment of radioactive aqueous and organic liquids (solvent, oil, solvent/oil mixing etc) and sludge through a mechanical and chemical solidification process. For Cadarache LOR, N910 and N960 respectively dedicated to the organic and aqueous liquids solidification are considered. With the N910, the organic waste solidification occurs in two steps. As the organic liquid travels moves through the polymer strands, the strands swell and immobilise the liquid. Then as the

  4. 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.

  5. 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.)

  6. Modeling and Simulation of CO2 Absorption into Promoted Aqueous Potassium Carbonate Solution in Industrial Scale Packed Column

    Directory of Open Access Journals (Sweden)

    Ali Altway

    2015-07-01

    Full Text Available Carbon dioxide gas is a harmful impurity which is corrosive and it can damage the utilities and the piping system in industries. Chemical absorption is the most economical separation method which is widely applied in chemical industries for CO2 removal process. Hot potassium carbonate (K2CO3 is the most effective solvent that has been used extensively, especially for the CO2 separation process from gas synthesis and natural gas. This paper aims to develop mathematical model for investigating the CO2 absorption into promoted hot K2CO3 solution in industrial scale packed column in an ammonia plant. The CO2 was removed from the gas stream by counter-current absorption in two stages column. To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory was considered. The model consists of differential mass and heat balance and considers the interactions between mass-transfer and chemical kinetics using enhancement factor concept. Gas solubility, mass and heat transfer coefficients, reaction kinetics and equilibrium were estimated using correlations from literatures. The model was validated using plant data and was used to compute temperature and concentration profiles in the absorber. The variation of CO2 recovery with respect to changes in some operating variables was evaluated. The effect of various kinds of promoters added into K2CO3 solution on the CO2 recovery was also investigated. The simulation results agree well with the plant data. The results of the simulation prediction, for the absorber pressure of 33 atm with a lean flow rate of 32,0867 kg/h, temperature of 343 K, and semi lean flow rate of 2,514,122 kg/h, temperature of 385 K, showed %CO2 removal of 95.55%, while that of plant data is 96.8%. © 2015 BCREC UNDIP. All rights reservedReceived: 3rd July 2014; Revised: 5th January 2015; Accepted: 19th Januari 2015How to Cite: Altway, A., Susianto, S., Suprapto, S., Nurkhamidah, S., Nisa, N.I.F., Hardiyanto

  7. Aqueous processing of low-band-gap polymer solar cells using roll-to-roll methods.

    Science.gov (United States)

    Andersen, Thomas R; Larsen-Olsen, Thue T; Andreasen, Birgitta; Böttiger, Arvid P L; Carlé, Jon E; Helgesen, Martin; Bundgaard, Eva; Norrman, Kion; Andreasen, Jens W; Jørgensen, Mikkel; Krebs, Frederik C

    2011-05-24

    Aqueous nanoparticle dispersions of a series of three low-band-gap polymers poly[4,8-bis(2-ethylhexyloxy)benzo(1,2-b:4,5-b')dithiophene-alt-5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)(2,1,3-benzothiadiazole)-5,5'-diyl] (P1), poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (P2), and poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (P3) were prepared using ultrasonic treatment of a chloroform solution of the polymer and [6,6]-phenyl-C(61)-butyric acid methyl ester ([60]PCBM) mixed with an aqueous solution of sodium dodecylsulphate (SDS). The size of the nanoparticles was established using small-angle X-ray scattering (SAXS) of the aqueous dispersions and by both atomic force microscopy (AFM) and using both grazing incidence SAXS (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS) in the solid state as coated films. The aqueous dispersions were dialyzed to remove excess detergent and concentrated to a solid content of approximately 60 mg mL(-1). The formation of films for solar cells using the aqueous dispersion required the addition of the nonionic detergent FSO-100 at a concentration of 5 mg mL(-1). This enabled slot-die coating of high quality films with a dry thickness of 126 ± 19, 500 ± 25, and 612 ± 22 nm P1, P2, and P3, respectively for polymer solar cells. Large area inverted polymer solar cells were thus prepared based on the aqueous inks. The power conversion efficiency (PCE) reached for each of the materials was 0.07, 0.55, and 0.15% for P1, P2, and P3, respectively. The devices were prepared using coating and printing of all layers including the metal back electrodes. All steps were carried out using roll-to-roll (R2R) slot-die and screen printing methods on flexible substrates. All five layers were processed using environmentally friendly methods and solvents. Two of the layers were processed entirely from water (the electron transport layer and the active

  8. Influence of Formulation and Processing Variables on Properties of Itraconazole Nanoparticles Made by Advanced Evaporative Precipitation into Aqueous Solution

    OpenAIRE

    Bosselmann, Stephanie; Nagao, Masao; Chow, Keat T.; Williams, Robert O.

    2012-01-01

    Nanoparticles, of the poorly water-soluble drug, itraconazole (ITZ), were produced by the Advanced Evaporative Precipitation into Aqueous Solution process (Advanced EPAS). This process combines emulsion templating and EPAS processing to provide improved control over the size distribution of precipitated particles. Specifically, oil-in-water emulsions containing the drug and suitable stabilizers are sprayed into a heated aqueous solution to induce precipitation of the drug in form of nanoparti...

  9. Bioremediation of zirconium from aqueous solution by coriolus versicolor: process optimization

    International Nuclear Information System (INIS)

    In the present study the potential of live mycelia of Coriolus versicolor was explored for the removal of zirconium from simulated aqueous solution. Optimum experimental parameters for the bioremediation of zirconium using C. versicolor biomass have been investigated by studying the effect of mycelia dose, concentration of zirconium, contact time and temperature. The isothermal studies indicated that the ongoing bioremediation process was exothermic in nature and obeyed Langmuir adsorption isotherm model. The Gibbs free energy (ΔG), entropy (ΔS) and enthalpy (ΔH) of bioremediation were also determined. The result showed that bioremediation of zirconium by live C. versicolor was feasible and spontaneous at room temperature. The equilibrium data verified the involvement of chemisorption during the bioremediation. The kinetic data indicated the operation of pseudo-second order process during the biosorption of zirconium from aqueous solution. Maximum bioremediation capacity (110.75 mg/g) of C. versicolor was observed under optimum operational conditions: pH 4.5, biomass dose 0.05 mg/100 mL, contact time 6 h and temperature 30 degree C. The results showed that C. versicolor could be used for bioremediation of heavy metal ions from aqueous systems. (author)

  10. Analysis of the electrodeposition process of rhenium and rhenium oxides in alkaline aqueous electrolyte

    International Nuclear Information System (INIS)

    Highlights: • The electrodeposition of rhenium and rhenium oxides from alkaline aqueous electrolyte was investigated. • The authors propose that the electrocrystallization process follows a multi-step reduction mechanism. • The electrodeposited material corresponds to a mixture of metallic rhenium, rhenium (IV) oxide and rhenium (VI) oxide. -- Abstract: The electrodeposition of rhenium and rhenium oxides from an alkaline aqueous solution containing 0.125 mol dm−3 NH4ReO4 + 0.01 mol dm−3 NaOH (pH 13.3 ± 0.1) has been studied. Cyclic voltammetry studies were carried out using two electrodes, polycrystalline platinum and polycrystalline gold, and the galvanostatic electrodeposition was conducted on a pure copper electrode (99.9%). Information regarding rhenium electrodeposits has been obtained by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results in an alkaline aqueous electrolyte suggest that the electrocrystallization process follows a multi-step mechanism influenced by hydrogen adsorption. The main conclusion was that rhenium, rhenium (IV) oxide and rhenium (VI) oxide coexist in the electrodeposited material

  11. Recovery of nickel from aqueous solutions by complexation-ultrafiltration process with sodium polyacrylate and polyethylenimine.

    Science.gov (United States)

    Shao, Jiahui; Qin, Shu; Davidson, Joshua; Li, Wenxi; He, Yiliang; Zhou, H Susan

    2013-01-15

    The recovery of nickel from aqueous dilute solutions by complexation-ultrafiltration process with sodium polyacrylate (PAAS) and polyethylenimine (PEI) was studied. Experiments were performed as a function of aqueous pH, polymer/Ni(2+) ratio and background electrolyte concentration. At optimum experimental conditions, the nickel removal rate reaches 99.5% using PAAS and 93.0% using PEI as the complexation agent. The nickel removal rate was found to decrease as the adding salt NaCl concentration increases for both complexation agents. A series of experiments implied that the mechanism could be the compressing electric double layer other than the competitive complexation. Diafiltration technique was further performed to regenerate complexation agents and recover nickel. The nickel removal rates were found to be close to those obtained with the original PEI and PAAS. Finally, Langmuir-type binding isotherm equation was employed to evaluate the extent of nickel bound to PAAS and PEI. The overall results from the two-step process of complexation-UF and decomplexation-UF separation showed that it could be a promising method for nickel removal and recovery from aqueous solutions. PMID:23177250

  12. 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

  13. REMOVAL OF REMAZOL ROSSO RB DYE FROM AQUEOUS EFFLUENTS BY HOMOGENOUS FENTON OXIDATION PROCESSES

    Directory of Open Access Journals (Sweden)

    Carmen Zaharia

    2014-06-01

    Full Text Available The paper presents some data from our laboratory-setup experiments of homogenous oxidative processes with hydrogen peroxide (i.e. advanced Fenton oxidation processes applied for Remazol Rosso RB dye-containing aqueous systems, especially textile effluents. Therefore, some different operating parameters (including pH, concentration of dye, H2O2 and ferrous ions, oxidation time, temperature, stirring regime, among its were tested for determination of the best performance in effluent decoloration and dye removal, meaning the optimal values of each studied parameters for highest decoloration or dye removal.

  14. Preparation of PtRu/carbon hybrids by hydrothermal carbonization process

    OpenAIRE

    Marcelo Marques Tusi; Michele Brandalise; Olandir Vercino Correa; Almir Oliveira Neto; Marcelo Linardi; Estevam Vitorio Spinacé

    2007-01-01

    PtRu/Carbon hybrids were prepared by hydrothermal carbonization process using glucose or starch as carbon sources and reducing agents and platinum and ruthenium salts as catalysts of carbonization process and metals source. The obtained PtRu/Carbon materials were characterized by SEM/EDX, TGA, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry using the thin porous coating technique aiming fuel cell application. The catalytic activity was dependent...

  15. Inhibiting properties and adsorption of an amine based fatty acid corrosion inhibitor on carbon steel in aqueous carbon dioxide solutions

    Energy Technology Data Exchange (ETDEWEB)

    Buchweishaija, Joseph

    1997-12-31

    Carbon dioxide corrosion is a major corrosion problem in oil and gas production systems and many organic inhibitors have been tested and used to protect the substrate from corrosion. This thesis studies the mechanism of interaction of the inhibitor molecule with the metallic substrate and how this affects the dissolution rate of the metal. The performance of a commercial amine based fatty acid corrosion inhibitor has been investigated using rotating cylinder electrodes and carbon steel electrodes in CO{sub 2} saturated formation water in the temperature range between 35 to 80{sup o}C. The corrosion process was monitored by electrochemical impedance measurements, and at the end of each experiment full polarization curves were recorded. When the inhibitor was applied on noncorroded electrodes, high inhibitor performance, over 99.7%, was observed independent of temperature. On precorroded electrodes inhibitor performance was found to depend on temperature and time of precorrosion. Above 60{sup o}C, the inhibitor performance decreased with increasing time of precorrosion, presumably because of the formation of a corrosion film of either iron carbonate or a combination of iron carbonate and iron carbide which prevent the inhibitor from reaching the surface. The inhibitor protection efficiency was assumed to be associated with the degree of inhibitor coverage at the material surface, and adsorption isotherms have been calculated in the concentration range between 0.1 ppm and 100 ppm. A Langmuir isotherm was found to give the best fit. The inhibitor performance on a 2 days precorroded rotating electrode was investigated at different solution pH ranging between 4.5 and 6.5 at 35{sup o}C. 130 refs., 80 figs., 22 tabs.

  16. 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

  17. Removal of copper (II) from aqueous solutions by flotation using polyaluminum chloride silicate (PAX-XL60 S) as coagulant and carbonate ion as activator.

    Science.gov (United States)

    Ghazy, S E; Mahmoud, I A; Ragab, A H

    2006-01-01

    Flotation is a separation technology for removing toxic heavy metal ions from aqueous solutions. Here a simple and rapid flotation procedure is presented for the removal of copper(II) from aqueous solutions. It is based on the use of polyaluminum chloride silicate (PAX-XL60 S) as coagulant and flocculent, carbonate ion as activator and oleic acid (HOL) as surfactant. Both ion and precipitate flotation are included depending on the solution pH. Ion and precipitate flotation in the aqueous HOL-PAX-XL60 S-Cu2+-CO3(2-) system gave powerful preferential removal of Cu2+ (F -100%) over the HOL-PAX-XL60 S-Cu2+ system containing no CO3(2+) ion (F approximately 86%). The role of CO3(2-) ion is also evident from decreasing the dose of PAX-XL60 S from 700 mg l(-1) to 200 mg l(-1). The other parameters, influencing the flotation process, namely: metal ion, surfactant and PAX-XL60 S concentrations, ionic strength, temperature and foreign ions were examined. Moreover, the procedure was successfully applied to recover Cu2+ ions from different volumes up to 11 and from natural water samples. PMID:16457175

  18. Heavy metals removal from aqueous environments by electrocoagulation process- a systematic review.

    Science.gov (United States)

    Bazrafshan, Edris; Mohammadi, Leili; Ansari-Moghaddam, Alireza; Mahvi, Amir Hossein

    2015-01-01

    Heavy metals pollution has become a more serious environmental problem in the last several decades as a result releasing toxic materials into the environment. Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical processes were used for the treatment of domestic, industrial and agricultural effluents. The commonly used conventional biological treatments processes are not only time consuming but also need large operational area. Accordingly, it seems that these methods are not cost-effective for effluent containing toxic elements. Advanced oxidation techniques result in high treatment cost and are generally used to obtain high purity grade water. The chemical coagulation technique is slow and generates large amount of sludge. Electrocoagulation is an electrochemical technique with many applications. This process has recently attracted attention as a potential technique for treating industrial wastewater due to its versatility and environmental compatibility. This process has been applied for the treatment of many kinds of wastewater such as landfill leachate, restaurant, carwash, slaughterhouse, textile, laundry, tannery, petroleum refinery wastewater and for removal of bacteria, arsenic, fluoride, pesticides and heavy metals from aqueous environments. The objective of the present manuscript is to review the potential of electrocoagulation process for the treatment of domestic, industrial and agricultural effluents, especially removal of heavy metals from aqueous environments. About 100 published studies (1977-2016) are reviewed in this paper. It is evident from the literature survey articles that electrocoagulation are the most frequently studied for the treatment of heavy metal wastewater. PMID:26512324

  19. 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.

  20. 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.

  1. Process to minimize cracking of pyrolytic carbon coatings

    International Nuclear Information System (INIS)

    Carbon-coated microspheroids useful as fuels in nuclear reactors are produced with a low percentage of cracked coatings and are imparted increased strength and mechanical stability characteristics by annealing immediately after the carbon coating processes

  2. The effect of electrochemical phenomena on the deposition of carbon containing inorganic thin films from supersonic expansion of aqueous supercritical solutions

    Science.gov (United States)

    Sezer, Ali Osman

    The supersonic expansion of dilute aqueous solutions for the synthesis of new materials is a complex flow system. Flow prediction and modeling are, therefore, quite challenging. Electrokinetic streaming potentials generated during the supersonic nozzle expansion further complicate the nature of these flow processes. Flow-generated potentials are believed to significantly affect the electrochemical environment of the flow, and therefore, may influence the properties of the product. This dissertation research was an attempt to experimentally and theoretically investigate the significance of flow-generated electrochemical phenomena and their possible effect on the deposited thin carbon films. Brand's computer model was used to predict the physical properties of the expanding jet at the nozzle. The sensitivity of the predicted flow parameters to operating conditions was then analyzed. The results of this parametric flow modeling were used to identify deposition regions of flow space that have less sensitivity to fluctuations in process temperatures and pressures. Streaming currents were predicted from measured nozzle currents. The first high-temperature-pressure Pourbaix diagrams were constructed for the carbon-water system. Equilibrium Pourbaix diagrams together with predicted streaming currents suggested a possible CVD-like mechanism for the deposition of thin carbon films. Deposited carbon films were analyzed for morphology, composition and structure by vibrational spectroscopy and electron microscopy. IR and Raman analysis of carbon samples were not conclusive in revealing any measurable differences in samples. Although Raman spectra showed considerable shifts in peak positions, the lack of internal standard in the spectra made it difficult to draw any reliable conclusions. Significant variations in surface morphology were found for samples grown under different substrate bias. Electron diffraction analysis conclusively showed the presence of a cubic diamond and

  3. Deconvoluting hepatic processing of carbon nanotubes

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  4. Metaldehyde removal from aqueous solution by adsorption and ion exchange mechanisms onto activated carbon and polymeric sorbents

    International Nuclear Information System (INIS)

    Highlights: ► First detailed analysis and study on metaldehyde removal by physical adsorbents. ► Adsorption performance of current method studied to probe reasons for failure of removal. ► Sorption performances of proposed alternative materials studied and mechanism proposed. ► Mechanism explains full sorption and degradation of metaldehyde. ► Results are of marked significance to the water treatment industries. -- Abstract: Metaldehyde removal from aqueous solution was evaluated using granular activated carbon (GAC), a non-functionalised hyper-cross-linked polymer Macronet (MN200) and an ion-exchange resin (S957) with sulfonic and phosphonic functional groups. Equilibrium experimental data were successfully described by Freundlich isotherm models. The maximum adsorption capacity of S957 (7.5 g metaldehyde/g S957) exceeded those of MN200 and GAC. Thermodynamic studies showed that sorption of metaldehyde onto all sorbents is endothermic and processes are controlled by entropic rather than enthalpic changes. Kinetic experiments demonstrated that experimental data for MN200 and GAC obey pseudo-second order models with rates limited by particle diffusion. Comparatively, S957 was shown to obey a pseudo-first order model with a rate-limiting step of metaldehyde diffusion through the solid/liquid interface. Results obtained suggest that metaldehyde adsorption onto MN200 and GAC are driven by hydrophobic interactions and hydrogen bonding, as leaching tendencies were high since no degradation of metaldehyde occurred. Conversely, adsorption of metaldehyde onto S957 occurs via ion-exchange processes, where sulfonic and phosphonic functionalities degrade adsorbed metaldehyde molecules and failure to detect metaldehyde in leaching studies for S957 supports this theory. Consequently, the high adsorption capacity and absence of leaching indicate S957 is promising for metaldehyde removal from source water

  5. Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

    Science.gov (United States)

    Suvorova, E. I.; Klechkovskaya, V. V.

    2010-12-01

    Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization in the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.

  6. Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

    Energy Technology Data Exchange (ETDEWEB)

    Suvorova, E. I., E-mail: suvorova@ns.crys.ras.ru; Klechkovskaya, V. V. [Shubnikov Institute of Crystallography of Russian Academy of Sciences (Russian Federation)

    2010-12-15

    Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization in the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.

  7. Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

    International Nuclear Information System (INIS)

    Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization in the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.

  8. Characterization of carbon/carbon composites prepared by different processing routes including liquid pitch densification process

    International Nuclear Information System (INIS)

    Carbon/carbon composites with an apparent density higher than 1.80 g/cm3 were prepared using a multi-step densification process. This consists of a pre-densification step followed by pitch impregnation/pyrolysis (I/P) cycles carried out under moderate pressure. Three pre-densification methods were investigated to significantly increase the apparent density of a raw preform to about 1.4 g/cm3. These were:(i) impregnation by carbonaceous powder slurry, (ii) film boiling chemical vapor infiltration, (iii) impregnation with a combination of synthetic pitch I/P and carbonaceous powder slurry. Composites were prepared from each of these three pre-densified materials, using a liquid pitch processing route with four I/P cycles with M50 petroleum pitch, under moderate pressures (10 MPa). As a reference a carbon/carbon composite was prepared using four I/P cycles with pitch. All four composites had different microstructural characteristics and different thermal properties. The influence of processing on thermal properties is discussed in relation to the microstructural characteristics. (authors)

  9. 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)

  10. Microbial carbon recycling: an underestimated process controlling soil carbon dynamics

    Science.gov (United States)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-07-01

    The mean residence times (MRT) of different compound classes of soil organic matter (SOM) do not match their inherent recalcitrance to decomposition. One reason for this is the stabilisation within the soil matrix, but recycling, i.e. the reuse of "old" organic material to form new biomass may also play a role as it uncouples the residence times of organic matter from the lifetime of discrete molecules in soil. We analysed soil sugar dynamics in a natural 30 years old labelling experiment after a~wheat-maize vegetation change to determine the extent of recycling and stabilisation in plant and microbial derived sugars: while plant derived sugars are only affected by stabilisation processes, microbial sugars may be subject to both, stabilisation and recycling. To disentangle the dynamics of soil sugars, we separated different density fractions (free particulate organic matter (fPOM), light occluded particulate organic matter (≤1.6 g cm-3; oPOM1.6), dense occluded particulate organic matter (≤2 g cm-3; oPOM2) and mineral-associated organic matter (>2 g cm-3; Mineral)) of a~silty loam under long term wheat and maize cultivation. The isotopic signature of sugars was measured by high pressure liquid chromatography coupled to isotope ratio mass spectrometry (HPLC/IRMS), after hydrolysis with 4 M Trifluoroacetic acid (TFA). While apparent mean residence times (MRT) of sugars were comparable to total organic carbon in the bulk soil and mineral fraction, the apparent MRT of sugars in the oPOM fractions were considerably lower than those of the total carbon of these fractions. This indicates that oPOM formation was fuelled by microbial activity feeding on new plant input. In the bulk soil, mean residence times of the mainly plant derived xylose (xyl) were significantly lower than those of mainly microbial derived sugars like galactose (gal), rhamnose (rha), fucose (fuc), indicating that recycling of organic matter is an important factor regulating organic matter dynamics

  11. 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)

  12. 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.

  13. Dynamic simulation of the carbon-in-pulp and carbon-in-leach processes

    Directory of Open Access Journals (Sweden)

    L. R. P. de Andrade Lima

    2007-12-01

    Full Text Available Carbon-in-leach and carbon-in-pulp are continuous processes that use activated carbon in a cascade of large agitated tanks, which have been widely used to recover or concentrate precious metals in gold extraction plants. In the carbon-in-pulp process adsorption occurs after the leaching cascade section of the plant, and in the carbon-in-leach process leaching and adsorption occur simultaneously. In both processes the activated carbon is moved from one tank to another in countercurrent with the ore pulp until the recovery of the loaded carbon in the first tank. This paper presents a dynamic model that describes, with minor changes, the carbon-in-leach, the carbon-in-pulp, and the gold leaching processes. The model is numerically solved and calibrated with experimental data from a plant and used to perform a study of the effect of the activated carbon transfer strategy on the performance of the adsorption section of the plant. Based on the calculated values of the gold loss in the liquid and of the gold recovered in the loaded activated carbon that leaves the circuit, the results indicate that strategies in which a significant amount of activated carbon is held in the first tank and the contact time between the carbon and the pulp is longer are the best carbon transfer strategies for these processes.

  14. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  15. Ultrafast formation of air-processable and high-quality polymer films on an aqueous substrate.

    Science.gov (United States)

    Noh, Jonghyeon; Jeong, Seonju; Lee, Jung-Yong

    2016-01-01

    Polymer solar cells are attracting attention as next-generation energy sources. Scalable deposition techniques of high-quality organic films should be guaranteed to realize highly efficient polymer solar cells in large areas for commercial viability. Herein, we introduce an ultrafast, scalable, and versatile process for forming high-quality organic films on an aqueous substrate by utilizing the spontaneous spreading phenomenon. This approach provides easy control over the thickness of the films by tuning the spreading conditions, and the films can be transferred to a variety of secondary substrates. Moreover, the controlled Marangoni flow and ultrafast removal of solvent during the process cause the films to have a uniform, high-quality nanomorphology with finely separated phase domains. Polymer solar cells were fabricated from a mixture of polymer and fullerene derivatives on an aqueous substrate by using the proposed technique, and the device exhibited an excellent power conversion efficiency of 8.44 %. Furthermore, a roll-to-roll production system was proposed as an air-processable and scalable commercial process for fabricating organic devices. PMID:27507624

  16. Ultrafast formation of air-processable and high-quality polymer films on an aqueous substrate

    Science.gov (United States)

    Noh, Jonghyeon; Jeong, Seonju; Lee, Jung-Yong

    2016-08-01

    Polymer solar cells are attracting attention as next-generation energy sources. Scalable deposition techniques of high-quality organic films should be guaranteed to realize highly efficient polymer solar cells in large areas for commercial viability. Herein, we introduce an ultrafast, scalable, and versatile process for forming high-quality organic films on an aqueous substrate by utilizing the spontaneous spreading phenomenon. This approach provides easy control over the thickness of the films by tuning the spreading conditions, and the films can be transferred to a variety of secondary substrates. Moreover, the controlled Marangoni flow and ultrafast removal of solvent during the process cause the films to have a uniform, high-quality nanomorphology with finely separated phase domains. Polymer solar cells were fabricated from a mixture of polymer and fullerene derivatives on an aqueous substrate by using the proposed technique, and the device exhibited an excellent power conversion efficiency of 8.44 %. Furthermore, a roll-to-roll production system was proposed as an air-processable and scalable commercial process for fabricating organic devices.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Evaluation of Electro-Fenton Process Performance for COD and Reactive Blue 19 Removal from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Mohammad Malakootian

    2013-02-01

    Full Text Available Background and Objectives: Synthetic dyes represent one of the largest groups of pollutants in wastewater of dying industries. Discharging these wastewaters into receiving streams not only affects the aesthetic but also reduces photosynthetic activity. Electrochemical advanced oxidation processes such as Electro-Fenton process are low operational and have high mineralization degree of pollutants. In this study, we investigated affective factors in this process to determine the optimum conditions for dye and COD removal from aqueous solutions containing Reactive Blue 19 dye.Materials and Methods: Synthetic samples containing Reactive Blue 19 dye were prepared by dissolving dye powder in double distilled water. and the the solution prepared was transferred into pilot electrochemical cell having two anode and cathode electrode made of iron and carbon. Electro-Fenton process was began by adding of Fe2+ ions and establishing electrical potential difference. After testing and at specified time intervals, each sample was collected from the pilot cell, and process performance was evaluated through measuring dye concentration and COD. Results: Based on the results obtained, optimum conditions of Electro-Fenton process for dye and COD removal was determined. Accordingly, potential difference of 20 volt for dye concentration up to 100 mg/L and potential difference of 30 volt for dye concentration of more than 200 mg/L, reaction time 60 minutes, 0.5 mg/L of Fe2+ concentration and suitable pH for the maximum dye removal efficiency equaled 4 respectively. Under such conditions, the dye and COD removal was 100 and 95% respectively.Conclusion: Based on the results obtained, it was revealed that Electro-Fenton process has significant ability in not only dye removal but also in COD removal. Accordingly, it was found that the effective parameters in Electro-Fenton process for removal Reactive Blue19 dye are electric potential difference, concentration of iron ions

  2. Antifouling foldable acrylic IOLs loaded with norfloxacin by aqueous soaking and by supercritical carbon dioxide technology.

    Science.gov (United States)

    González-Chomón, Clara; Braga, Mara E M; de Sousa, Herminio C; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2012-10-01

    Cataracts treatment usually involves the extraction of the opaque crystalline lens and its replacement by an intraocular lens (IOL). A serious complication is the occurrence of endophthalmitis, a post-surgery infection mainly caused by Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. IOLs having the ability to load and to release norfloxacin in a controlled way and at efficient therapeutic levels may help to overcome these issues. In this work, acrylic hydrogels combining 2-hydroxyethyl methacrylate (HEMA) and 2-butoxyethyl methacrylate (BEM) at various ratios were prepared to attain biocompatible networks that can be foldable even in the dry state and thus insertable through minor ocular incision, and that load therapeutic amounts of norfloxacin. Acrylamide (AAm) and methacrylic acid (MAAc) were also incorporated as functional comonomers in small proportions. Water sorption, contact angle, protein adsorption, and optical properties of the networks were characterized. BEM notably decreased the T(g) of the networks, but also the loading by immersion in aqueous solution (presoaking). Then, a scCO(2)-based impregnation/deposition (SSI) method was implemented to improve the uptake of the drug. Loading capacities were discussed in terms of the comonomers composition and the employed method and operational conditions. The networks prepared with HEMA/BEM 20:80 vol/vol and processed with supercritical fluids combine adequate mechanical properties, biocompatibility and norfloxacin loading/release, and seem to be suitable for developing norfloxacin-eluting IOLs. PMID:22846620

  3. Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents

    Energy Technology Data Exchange (ETDEWEB)

    Saucier, Caroline [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Adebayo, Matthew A. [Department of Chemical Sciences, Ajayi Crowther University, Oyo, Oyo State (Nigeria); Lima, Eder C., E-mail: eder.lima@ufrgs.br [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Cataluña, Renato [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Thue, Pascal S. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Department of Applied Chemistry, University of Ngaoundere, P.O. Box 455, Ngaoundere (Cameroon); Prola, Lizie D.T.; Puchana-Rosero, M.J. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Machado, Fernando M. [Technology Development Center, Federal University of Pelotas (UFPEL), Pelotas (Brazil); Pavan, Flavio A. [Institute of Chemistry, Federal University of Pampa (UNIPAMPA), Bagé, RS (Brazil); Dotto, G.L. [Chemical Engineering Department, Federal University of Santa Maria (UFSM), Santa Maria, RS (Brazil)

    2015-05-30

    Highlights: • Microwave-assisted cocoa shell activated carbon was prepared and characterized. • The anti-inflammatories, diclofenac and nimesulide, were adsorbed onto MWCS-1.0. • Adsorption maximum values are 63.47 (diclofenac) and 74.81 mg g{sup −1} (nimesulide). • General order kinetic model suitably explained the adsorption process. • MWCS-1.0 was effectively used for treatment of simulated hospital effluents. - Abstract: Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L{sup −1} HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N{sub 2} adsorption/desorption curves, X-ray diffraction, and point of zero charge (pH{sub pzc}). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g{sup −1}, respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations.

  4. 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.

  5. 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 >...

  6. Multifunctional modification of wool using an enzymatic process in aqueous-organic media.

    Science.gov (United States)

    Hossain, Kh M Gaffar; González, María Díaz; Lozano, Guillem Rocasalbas; Tzanov, Tzanko

    2009-04-20

    An enzymatic method using laccases for grafting the water insoluble phenolic compound lauryl gallate on wool fabric was developed. To find the compromise conditions at which the substrate is soluble while the enzyme remains active, the reaction was carried out in an 80/20 (v/v, %) aqueous-ethanol mixture, where the enzyme retains 75-80% of its activity. The enzymatic coating of wool with lauryl gallate provided in a one-step process a multifunctional textile material with antioxidant, antibacterial and water repellent properties. PMID:19428731

  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

    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.

  8. Effectiveness of Quercus Branti Activated Carbon in Removal of Methylene Blue from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Abdolmotaleb Seidmohammadi

    2015-10-01

    Full Text Available Background & Aims of the Study: Dyes are one of the most contaminants in textile industrial wastewater that they are often carcinogenic, mutagenic and non-degradable. Therefore, with regard to environmental aspects, their removal from effluents is very essential. The purpose of this study was the perception of adsorption process and promotion of an economic technology for colored wastewater treatment. Therefore, activated carbon from Oak fruit bark was used as an effective and economic adsorbent. Materials & Methods: This study was performed at laboratory scale and batch system. At present study, the adsorbent surface properties was evaluated by use of the (FT-IR test and scanning electronic microscope (SEM. Also, effect of various operating parameters such as pH, contact time, adsorbent dose, initial dye concentration and temperature on dye removal from synthetic wastewater were studied. Results: In this study, maximum removal efficiency of methylene blue were achieved at optimal pH=6, reaction time 180 minutes, and adsorbent dose 2 gl-1. Methylene blue removal efficiency with initial concentration of 100 mg.l-1 was 91.08%. Conclusions: According to results, it was cleared that : Quercus branti activated carbon can be used as an effective and economic adsorbent in waste water treatment processes.

  9. 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.

  10. Elimination and Recycling of Imatinib by Ethoxylated Multi-Walled Carbon Nanotubes from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Maryam Pakzad Masouleh

    2015-06-01

    Full Text Available An adsorbent and carrier based on ethoxylated functionalized multi-walled carbon nanotubes (f-MWCNTs were prepared with diethylene glycol (2EG followed by esterification process. Resultant dietylene glycolated MWCNTs (MWCNTs-2EG used for elimination of Imatinib mesylate (Ima from water. Maximum Ima adsorption per 3 mg of adsorbent and 9 mg of initial Ima was 8.76 mg. maximum recycling at two pH values 7.4 and 5.3 was determined about 6.15 mg (70% and 7.42 mg (85% respectively. Ima elimination and recycling process is greatly enhanced by the creation of functional groups on the MWCNTs-2EG in compare with carboxylated MWCNTs (MWCNTs-COOH.

  11. 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)

  12. Identification of light absorbing oligomers from glyoxal and methylglyoxal aqueous processing: a comparative study at the molecular level

    Science.gov (United States)

    Finessi, Emanuela; Hamilton, Jacqueline; Rickard, Andrew; Baeza-Romero, Maria; Healy, Robert; Peppe, Salvatore; Adams, Tom; Daniels, Mark; Ball, Stephen; Goodall, Iain; Monks, Paul; Borras, Esther; Munoz, Amalia

    2014-05-01

    Numerous studies point to the reactive uptake of gaseous low molecular weight carbonyls onto atmospheric waters (clouds/fog droplets and wet aerosols) as an important SOA formation route not yet included in current models. However, the evaluation of these processes is challenging because water provides a medium for a complex array of reactions to take place such as self-oligomerization, aldol condensation and Maillard-type browning reactions in the presence of ammonium salts. In addition to adding to SOA mass, aqueous chemistry products have been shown to include light absorbing, surface-active and high molecular weight oligomeric species, and can therefore affect climatically relevant aerosol properties such as light absorption and hygroscopicity. Glyoxal (GLY) and methylglyoxal (MGLY) are the gaseous carbonyls that have perhaps received the most attention to date owing to their ubiquity, abundance and reactivity in water, with the majority of studies focussing on bulk physical properties. However, very little is known at the molecular level, in particular for MGLY, and the relative potential of these species as aqueous SOA precursors in ambient air is still unclear. We have conducted experiments with both laboratory solutions and chamber-generated particles to simulate the aqueous processing of GLY and MGLY with ammonium sulphate (AS) under typical atmospheric conditions and investigated their respective aging products. Both high performance liquid chromatography coupled with UV-Vis detection and ion trap mass spectrometry (HPLC-DAD-MSn) and high resolution mass spectrometry (FTICRMS) have been used for molecular identification purposes. Comprehensive gas chromatography with nitrogen chemiluminescence detection (GCxGC-NCD) has been applied for the first time to these systems, revealing a surprisingly high number of nitrogen-containing organics (ONs), with a large extent of polarities. GCxGC-NCD proved to be a valuable tool to determine overall amount and rates of

  13. 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.

  14. Thermal stabilisation process for aqueous solutions of polysaccharides, and their use in boring fluids. Procede de stabilitaion thermique de solutions aqueuses de polysaccharides et son application aux fluides de forage

    Energy Technology Data Exchange (ETDEWEB)

    Vio, L.; Meunier, G.

    1987-01-06

    This invention concerns a process for heat stabilization of aqueous xanthane or scleroglucane solutions. To said solution, 150-5,000 ppM of an alkali metal dialkyl-dithiocarbamate is added, of which the alkyl portions each contain 1-12 carbon atoms. In said solution, a quantity of sodium chloride is maintained, corresponding to a 0.4-6 N concentration. The solution can also contain up to 20 g/l of CaCl/sub 2/. The aqueous solutions stabilized by this process are notably used in making up drilling fluids for petroleum recovery.

  15. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    Directory of Open Access Journals (Sweden)

    Renwu Zhou

    Full Text Available Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS. Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma.

  16. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution

    Science.gov (United States)

    Zhou, Renwu; Zhou, Rusen; Zhuang, Jinxing; Zong, Zichao; Zhang, Xianhui; Liu, Dongping; Bazaka, Kateryna; Ostrikov, Kostya

    2016-01-01

    Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. PMID:27183129

  17. An Integrated, Low Temperature Process to Capture and Sequester Carbon Dioxide from Industrial Emissions

    Science.gov (United States)

    Wendlandt, R. F.; Foremski, J. J.

    2013-12-01

    Laboratory experiments show that it is possible to integrate (1) the chemistry of serpentine dissolution, (2) capture of CO2 gas from the combustion of natural gas and coal-fired power plants using aqueous amine-based solvents, (3) long-term CO2 sequestration via solid phase carbonate precipitation, and (4) capture solvent regeneration with acid recycling in a single, continuous process. In our process, magnesium is released from serpentine at 300°C via heat treatment with ammonium sulfate salts or at temperatures as low as 50°C via reaction with sulfuric acid. We have also demonstrated that various solid carbonate phases can be precipitated directly from aqueous amine-based (NH3, MEA, DMEA) CO2 capture solvent solutions at room temperature. Direct precipitation from the capture solvent enables regenerating CO2 capture solvent without the need for heat and without the need to compress the CO2 off gas. We propose that known low-temperature electrochemical methods can be integrated with this process to regenerate the aqueous amine capture solvent and recycle acid for dissolution of magnesium-bearing mineral feedstocks and magnesium release. Although the direct precipitation of magnesite at ambient conditions remains elusive, experimental results demonstrate that at temperatures ranging from 20°C to 60°C, either nesquehonite Mg(HCO3)(OH)●2H2O or a double salt with the formula [NH4]2Mg(CO3)2●4H2O or an amorphous magnesium carbonate precipitate directly from the capture solvent. These phases are less desirable for CO2 sequestration than magnesite because they potentially remove constituents (water, ammonia) from the reaction system, reducing the overall efficiency of the sequestration process. Accordingly, the integrated process can be accomplished with minimal energy consumption and loss of CO2 capture and acid solvents, and a net generation of 1 to 4 moles of H2O/6 moles of CO2 sequestered (depending on the solid carbonate precipitate and amount of produced H2

  18. 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

  19. Preparation of PtRu/carbon hybrids by hydrothermal carbonization process

    Directory of Open Access Journals (Sweden)

    Marcelo Marques Tusi

    2007-06-01

    Full Text Available PtRu/Carbon hybrids were prepared by hydrothermal carbonization process using glucose or starch as carbon sources and reducing agents and platinum and ruthenium salts as catalysts of carbonization process and metals source. The obtained PtRu/Carbon materials were characterized by SEM/EDX, TGA, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry using the thin porous coating technique aiming fuel cell application. The catalytic activity was dependent of carbon source and time used in the synthesis.

  20. Adsorption of crystal violet with diatomite earth&carbon by a modification of hydrothermal carbonization process.

    Science.gov (United States)

    Zhang, Yanzhuo; Li, Jun; Chen, Guanghui; Bian, Wei; Lu, Yun; Li, Wenjing; Zheng, Zhaoming; Cheng, Xiaojie

    2016-01-01

    The high colority and difficulty of decolorization are the most important tasks on printing and dyeing wastewater. This study investigates the ability of diatomite earth&carbon (DE&C) as an adsorbent to removal crystal violet (CV) from aqueous solutions. Fourier transform infrared spectroscopy results indicate the importance of functional groups during the adsorption of CV. The obtained N2 adsorption-desorption isotherm values accord with well IUPAC type II. Our calculations determined a surface area of 73.15 m(2) g(-1) for DE&C and an average pore diameter of 10.56 nm. Equilibrium data of the adsorption process fitted very well to the Langmuir model (R(2) > 0.99). The results of kinetics study showed that the pseudo-second-order model fitted to the experimental data well. The thermodynamic parameters were also evaluated. ΔH° 0 and ΔG° dye. Furthermore the positive value of ΔS° reflected good affinity of the CV dye. PMID:27003089

  1. Carbon sequestration processes in tropical seagrass beds

    OpenAIRE

    Lyimo, Liberatus Dominick

    2016-01-01

    Seagrass meadows may play a substantial role in climate change mitigation as they are capable to sequester and store substantial amounts of anthropogenic carbon in plant biomass and, more importantly, in their underlying sediments. In this PhD thesis, the carbon-burial potential was assessed by quantifying the amount of organic carbon stored in different seagrass meadows, each dominated by one of the four major seagrass species in the Western Indian Ocean region. Impacts of anthropogenic dist...

  2. 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.

  3. 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)

  4. A new process for preparation of soybean protein concentrate with hexane-aqueous ethanol mixed solvents.

    Science.gov (United States)

    Zhang, Wei-Nong; Liu, Da-Chuan

    2005-01-01

    A new process for the preparation of soybean protein concentrate (SPC) by directly extracting full-fat soy flour with a mixture of hexane and aqueous ethanol was established. Compared with conventional methods, it has some advantages, such as saving energy and reducing protein denaturation caused by heat action during solvent recovery, because this process saves one step of solvent recovery. The effects of aqueous ethanol concentration and the mixure ratio (hexane to ethanol) on the degree of protein denaturation and product quality were investigated, on the basis of which the orthogonal tests were performed. The optimum technical parameters were obtained by analyzing the results of the orthogonal tests with statistical methods. We found that SPC can be obtained by extracting full-fat soy flour under the following conditions: mixture ratio hexane: 90% ethanol, 9:1, v/v; extraction temperature, 45 degrees C; ratio of solid to solvents, (1:2 w/v); and 5 repeated extractions (15 min each time). The results of quality analysis showed that solubility of the product was improved significantly [nitrogen solubility index (NSI) 46.6%] compared with that for ethanol washing of protein concentrate (NSI 8.7%). PMID:16152943

  5. Carbon-13 magnetic relaxation rates or iron (III) complexes of some biogenic amines and parent compounds in aqueous solutions

    International Nuclear Information System (INIS)

    Spin-lattice relaxation rates (R1) from naturally occuring C-13 F.T. N.M.R. spectra of some catecholamines and parent compounds with Iron(III) at pD = 4 were determined in order to elucidate the molecular mechanism underlying their association in aqueous solutions. Complexation was observed only for catecholic ligands. The R1 values were used to calculate iron-carbon scaled distances, and two complexation models were proposed where the catecholic function binds Fe(III) in the first and second coordination spheres respectively. The latter case was shown to be the consistent with the molecular geometries. (orig.)

  6. Covalent and non-covalent functionalization and solubilization of double-walled carbon nanotubes in nonpolar and aqueous media

    Indian Academy of Sciences (India)

    L S Panchakarla; A Govindaraj

    2008-11-01

    Double-walled carbon nanotubes (DWNTs) have been functionalized by both covalent and non-covalent means. Covalent functionalization has been carried out by attaching an aliphatic amide function to DWNTs which enable solubilization in non-polar solvents. Solubilization in non-polar solvents has also been accomplished by non-covalent functionalization by using 1-pyrenebutanoicacid succinimidyl ester (PYBS). Non-covalent functionalization of DWNTs has been carried out by using polyethylene glycol (PEG) and polyoxyethylene(40)nonylphenyl ether (IGPAL), both of which enable solubilization in aqueous media. These functionalized DWNTs have been characterized by transmission electron microscopy, IR and Raman spectroscopy.

  7. Kinetics of the Removal of Chromium Complex Dye from Aqueous Solutions Using Activated Carbons and Polymeric Adsorbent

    OpenAIRE

    Eglė Kazlauskienė; Danutė Kaušpėdienė

    2011-01-01

    The kinetics of the removal of chromium complex dye (Lanasyn Navy M-DNL) from aqueous solutions using polymeric adsorbent Macronet MN 200 (MN 200) as an alternative option for activated carbon Norit RB 0.8 CC (AC) was studied in the batch system. The residual colour of dye solution treated with AC or MN 200 strongly depends on solution pH with lower values at acidic pH when a positively charged surface net is favourable for the adsorption of the dye anion. The removal of dye using MN 200 was ...

  8. 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.

  9. An experimental design approach for modeling As(V) adsorption from aqueous solution by activated carbon.

    Science.gov (United States)

    Bakkal Gula, C; Bilgin Simsek, E; Duranoglu, D; Beker, U

    2015-01-01

    The present paper discusses response surface methodology as an efficient approach for predictive model building and optimization of As(V) adsorption on activated carbon derived from a food industry waste: peach stones. The objectives of the study are application of a three-factor 2³ full factorial and central composite design technique for maximizing As(V) removal by produced activated carbon, and examination of the interactive effects of three independent variables (i.e., solution pH, temperature, and initial concentration) on As(V) adsorption capacity. Adsorption equilibrium was investigated by using Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. First-order and second-order kinetic equations were used for modeling of adsorption kinetics. Thermodynamic parameters (ΔG °, ΔH °, and ΔS °) were calculated and used to explain the As(V) adsorption mechanism. The negative value of ΔH (-7.778 kJ mol⁻¹) supported the exothermic nature of the sorption process and the Gibbs free energy values (ΔG°) were found to be negative, which indicates that the As(V) adsorption is feasible and spontaneous. PMID:25633943

  10. Deconvoluting hepatic processing of carbon nanotubes.

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L J; Ulmert, Hans David S; Brea, Elliott J; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A; McDevitt, Michael R

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  11. Nanostructure-based Processes at the Carbonizing Steels

    Directory of Open Access Journals (Sweden)

    L.I. Roslyakova

    2015-12-01

    Full Text Available The studies of nanostructure-based processes carburizing steels showed that oxidizing atmosphere when carburizing steel contains along with carbon dioxide (CO2 + C = 2CO molecular and atmospheric oxygen (O2 + 2C = 2CO; O + C = CO released from the carbonate ВаСОз during its thermal dissociation. Intensive formation of CO provides high carbonizing ability of carbonate-soot coating and steel.

  12. Review of irradiated uranium recycling processes by non-aqueous method

    International Nuclear Information System (INIS)

    Recycling processes of irradiated uranium fuel by non aqueous method have been reviewed. The fluoride volatilization process is carried out by dissolving irradiated uranium fuel in BrF3 or CIF3 to produce UF6 volatile gas and PuF4 and fission products in fluoride form which are then separated by distillation. The chloride volatility process is used for U-Zr alloy fuel by using hydro chlorination process at temperature of 350-600oC to separate ZrCl4 volatile from UCI3 which is then dissolved and distilled. The processes which are carried out at high temperature are pyrochemical and pyrometallurgical. Development of fluorides volatility process for the separation of U-Pu from irradiated uranium fuel is fluidization technique. Oxidation and fluorination reaction can be carried out in a fluidized bed reactor. DUPIC process uses spent fuel of PWR which is directly pulverized into powder for Candu reactor fuel. The review shows that due to the advantage and simplicity, the pyrochemical and oxidation-reduction process can be developed in Indonesia to study the separation of U-Pu from fission products in the irradiated fuel. The fluidization technique can also be developed, but it needs a special facility to handle gaseous reagent. (author)

  13. Synthesis and utilization of a novel carbon nanotubes supported nanocables for the adsorption of dyes from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Jiang, Xinyu [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Chen, Xiaoqing, E-mail: xqchen@csu.edu.cn [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Collaborative Innovation Center of Resource-conserving & Environment-friendly Society and Ecological Civilization (China)

    2015-09-15

    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. - Graphical abstract: MWCNTs@carbon nanocables has been successfully fabricated by a hydrothermal carbonization method. The as-synthesized novel samples were used as adsorbents and exhibited high adsorption capacity on MB and CV. - Highlights: • A simple, cost-effective and “green” method for the synthesis of the material. • The diameter and length of the material are relatively easy to control. • The surface has large oxygen-containing groups and preferable chemical reactivity. • Compared with raw MWCNTs and some other adsorbents, the adsorption capacity is much high.

  14. Synthesis and utilization of a novel carbon nanotubes supported nanocables for the adsorption of dyes from aqueous solutions

    International Nuclear Information System (INIS)

    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. - Graphical abstract: MWCNTs@carbon nanocables has been successfully fabricated by a hydrothermal carbonization method. The as-synthesized novel samples were used as adsorbents and exhibited high adsorption capacity on MB and CV. - Highlights: • A simple, cost-effective and “green” method for the synthesis of the material. • The diameter and length of the material are relatively easy to control. • The surface has large oxygen-containing groups and preferable chemical reactivity. • Compared with raw MWCNTs and some other adsorbents, the adsorption capacity is much high

  15. Synthesis and characterization of conditioned carbon with iron nanoparticles for the arsenic removal in aqueous phase

    International Nuclear Information System (INIS)

    Using pineapple husks conditioned with carboxymethylcellulose, hexamine and ferric nitrate, a carbonaceous material was obtained with nanoparticles of Fe (C Fe), which was characterized and tested for arsenic removal in the aqueous phase. The microscopic study showed spheres 4 microns and filaments 100 nm wide, so as iron particles whose diameter decreases to an average of 38.81 nm, when pyrolysis time was increased to 180 min. their distribution in the carbonaceous matrix is homogeneous. According to energy dispersive X-ray spectroscopy, C Fe contains C (82.29%), O (7.23%), K (0.68%), Ca (3.77%) and Fe (6.25%) and its diffraction pattern shows the characteristic peak of Fe (0), which is not observed in the coal without iron. By neutron activation analysis were quantified Al, Br, Ce, Co, Cr, Cs, Eu, Hf, K, Mg, Mn, Na, Rb, Sb, Sc and Zn, they can be involved in the process of sorption of As (v) forming surface active sites. For C Fe and C B characterized by Fourier transform infrared spectrometry, groups C-H, C=O, C=C, -Nh, NH2, isocyanate and isonitrile were found, the last two were formed by the present hexamine. X-ray photoelectron spectroscopy showed energy states of C 1 and O 1 in pineapple shell washed, shell conditioned with iron, C Fe at different times and the pyrolysis coal without iron (C B). The material C Fe 180 presented a specific area of 167 m2/g and 7.12 ± 1 sites/nm2 isoelectric point while pHi = 11.1 C B is 98.80 m2/g specific area and 1.5 ± 1 sites/nm2 and pHi = 10.6, being favorable to the sorption process. The highest removal of As(v) for both materials was at ph = 2, fitting the kinetic data to pseudo-second order model. The isotherms as a function of concentration were adjusted to Freundlich model indicating multilayer chemisorption at specific sites of a heterogeneous medium. Characterization by scanning electron microscopy after the sample sorption Fe nanoparticles remain in the carbonaceous matrix being not affected by the agitation of

  16. Development of advanced aqueous reprocessing process in fast reactor cycle technology development (FaCT) project

    International Nuclear Information System (INIS)

    Japan Atomic Energy Agency (JAEA) has been implementing the 'Fast Reactor Cycle Technology Development (FaCT)' project in cooperation with electric utilities toward the commercialization of fast reactor cycle system in Japan before 2050. In the FaCT project, a combination system of 'the Japan Sodium-cooled Fast Reactor (JSFR) with oxide fuel, the advanced aqueous reprocessing, and the simplified pelletizing fuel fabrication' has been adopted pursuing full-actinides recycling in a closed cycle. In the advanced aqueous reprocessing concept, JAEA has proposed NEXT (New extraction system for TRU recovery) system consists of six innovative technologies (disassembling and shearing, fuel dissolution, uranium (U) crystallization, highly effective extraction system with group separation of U- plutonium (Pu) - neptunium (Np), MA recovery by extraction chromatography and Salt-free process for waste reduction ). Toward the present milestone in the FaCT project, the evaluation work to decide whether the innovative technologies can be adopted for the advanced aqueous reprocessing is in progress. So far, on the basis of the progress in design study and research works on the relevant innovative technologies, three technologies as disassembling/shearing, highly effective dissolution and effective uranium pre-recovery by crystallization are judged to be adoptable in the preliminary assessment by JAEA and electric utilities. The final decision will be made by the end of 2010. The selected technologies will be adopted for the conceptual design, and related research and development works will be carried out from 2011, and the future development program toward the commercialization until 2015 would be applied. (authors)

  17. Study of charge compensation during the redox process of self-doped polyaniline in aqueous media

    Directory of Open Access Journals (Sweden)

    Varela Hamilton

    2000-01-01

    Full Text Available One of the most important problems associated with use of polyaniline as a cathode material in rechargeable lithium batteries is related to energy density degradation due to the predomination of anion participation in the charge compensation process. This work describes the synthesis of a self-doped polyaniline, poly-(aniline-co-N-propanesulfonic acid-aniline, and evaluates its properties in aqueous acid solutions, with special attention to the increase of proton participation in the electroneutralization mechanism. The characterization was carried out using elemental analysis, FTIR and UV-vis spectroscopies. Electrochemical properties were investigated with the electrochemical quartz crystal microbalance and cyclic voltammetry. The results obtained show that proton participation was increased for the redox process of poly-(aniline-co- N-propanesulfonic-acid-aniline in relation to polyaniline.

  18. A novel process for the aqueous extraction of oil from Camellia oleifera seed and its antioxidant activity

    Directory of Open Access Journals (Sweden)

    Yu, X.

    2013-09-01

    Full Text Available Aqueous extraction is a promising green alternative to hexane extraction. This study used a salt effect-aided aqueous extraction process (AEP-SE for extracting Camellia oleifera seed oil (COSO to improve oil extractability and avoid emulsification in the aqueous system. The highest oil extractability rate of 88.8% was obtained under 1.48 mol L–1 sodium carbonate, a solution-to-flour ratio of 3.85, and 3.23h of extraction time with the quality of the aqueous system-extracted oil being similar to those of a commercial sample of COSO and hexane-extracted oil in terms of color, iodine value and saponifcation value, although its moisture content was higher. Furthermore, the free fatty acid content of the aqueous system-extracted oil was lower than that of the solvent-extracted oil. The values of the inibihitory concentration at 50% of oil obtained by AEP-SE and organic solvent extraction as measured by DPPH scavenging activity essay, were 2.27 mg/mL and 3.31 mg/mL. AEP-SE is therefore a promising environmentally friendly method for the large-scale preparation of COSO.La extracción acuosa es una alternativa verde muy prometedora a la extracción con hexano. En este estudio se utilizó como ayuda en el proceso de extracción acuosa (AEP-SE el efecto de una sal para la extracción de aceite de semilla de Camellia oleifera (COSO para mejorar la extractabilidad y evitar la formación de emulsiones en el sistema acuoso. La mayor velocidad de extracción de aceite, 88,8%, se obtuvo con una concentración de carbonato de sodio de 1,48 mol L–1, una relación de solución a la harina de 3,85, y 3.23h de tiempo de extracción, con una calidad del aceite extraído con el sistema acuoso similares a los de una muestra comercial de COSO extraida con hexano, en términos de índice de yodo, de color, y de índice de saponificación, aunque su contenido en humedad fue mayor. Además, el contenido de acidez libre del aceite extraido con el sistema acuoso fu

  19. The solubility of very low concentratiions of carbon monoxide in aqueous solution

    OpenAIRE

    Meadows, R. W.; Spedding, D. J.

    2011-01-01

    The solubility of carbon monoxide in natural waters has been determined when the partial pressure of carbon monoxide in the gas phase approaches atmospheric concentrations. For both pure water and seawater the solubilities were found to be more than eight times the values which have previously been observed with an atmosphere of pure carbon monoxide present. Carbon monoxide therefore does not obey Henry's law over the pressure range from approximately 10?5 atmospheres to greater than one atmo...

  20. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    DU GaoXiang; ZHENG ShuiLin; DING Hao

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The op-timum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liq-uid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  1. Degradation of aqueous methyl tert-butyl ether by photochemical, biological, and their combined processes

    Directory of Open Access Journals (Sweden)

    Azadeh Asadi

    2006-01-01

    Full Text Available The degradation of aqueous methyl tert-butyl ether (MTBE at relatively high concentrations was investigated by various photo-induced oxidation processes such as UV/H2O2 and UV/TiO2 as well as biological processes and their combination. It was shown that the degradation of MTBE by UV/H2O2 and TiO2 photocatalytic followed a first-order model with apparent rate constant of 1.31×10−1 and 1.21×10−2 min-1, respectively. It was observed that UV/H2O2/TiO2 process did not have any advantages over each of the other processes alone. The biodegradation of methyl tert-butyl ether (MTBE was evaluated using aerobic mixed culture with three different approaches, including ultimate biological oxygen demand (BODU assessment, nonacclimated, and acclimated mixed cultures. The apparent rate constant for the biodegradation of MTBE by nonacclimated mixed culture was 4.36×10−2 day-1. It was shown that the acclimatization of the mixed cultures enhanced the rate of biodegradation of MTBE to 3.24×10−1mg L-1h-1. Finally, the effects of the photocatalytic pretreatment of aqueous MTBE on its subsequent biological treatment were studied. It was observed that the rate of bioreaction was not enhanced and the photocatalytic pretreatment had adverse effects on its biological treatment so that the apparent rate constant decreased to 2.83×10−1 mg L-1h-1.

  2. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    International Nuclear Information System (INIS)

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH3CO2NH4) and sodium acetate (CH3CO2Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example

  3. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Bahk, Yeon Kyoung; He, Xu; Gitsis, Emmanouil; Kuo, Yu-Ying [ETH Zurich, Institute of Environmental Engineering (Switzerland); Kim, Nayoung [EMPA, Building Energy Materials and Components (Switzerland); Wang, Jing, E-mail: jing.wang@ifu.baug.ethz.ch [ETH Zurich, Institute of Environmental Engineering (Switzerland)

    2015-10-15

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH{sub 3}CO{sub 2}NH{sub 4}) and sodium acetate (CH{sub 3}CO{sub 2}Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example.

  4. Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent

    International Nuclear Information System (INIS)

    A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment.

  5. Synthesis of magnetic nanoporous carbon from metal-organic framework for the fast removal of organic dye from aqueous solution

    Science.gov (United States)

    Jiao, Caina; Wang, Yanen; Li, Menghua; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2016-06-01

    In this paper, a magnetic nanoporous carbon (Fe3O4/NPC) was successfully synthesized by using MOF-5 as carbon precursor and Fe salt as magnetic precursor. The texture properties of the as-synthesized nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometer (VSM), and N2 adsorption-desorption isotherms. The Fe3O4/NPC had a high surface area with strong magnetic strength. Its adsorption behavior was tested by its adsorption capacity for the removal of methylene blue from aqueous solution. The results demonstrated that the Fe3O4/NPC had a high adsorption capacity, rapid adsorption rate, and easy magnetic separabilty. Moreover, the adsorbent could be easily regenerated by washing it with ethanol. The Fe3O4/NPC can be used as a good alternative for the effective removal of organic dyes from wastewater.

  6. Processing of thermo-structural carbon-fiber reinforced carbon composites

    Directory of Open Access Journals (Sweden)

    Luiz Cláudio Pardini

    2009-06-01

    Full Text Available The present work describes the processes used to obtain thermostructural Carbon/Carbon composites. The processing of these materials begins with the definition of the architecture of the carbon fiber reinforcement, in the form of stacked plies or in the form of fabrics or multidirectional reinforcement. Incorporating fiber reinforcement into the carbon matrix, by filling the voids and interstices, leads to the densification of the material and a continuous increase in density. There are two principal processing routes for obtaining these materials: liquid phase processing and gas phase processing. In both cases, thermal processes lead to the formation of a carbon matrix with specific properties related to their precursor. These processes also differ in terms of yield. With liquid phase impregnation the yield is around 45 per cent, while gas phase processing yields around 15 per cent.

  7. Mechanism for the formation of elemental sulfur from aqueous sulfide in chemical and microbiological desulfurization processes

    Energy Technology Data Exchange (ETDEWEB)

    Steudel, R. [Technische Univ. Berlin (Germany). Inst. fuer Anorganische und Analytische Chemie

    1996-04-01

    A detailed reaction mechanism is proposed for the formation of crystalline elemental sulfur from aqueous sulfide by oxidation with transition-metal ions like V{sup 5}, Fe{sup 3}, Cu{sup 2}, etc. The first step is the formation of HS{center_dot} radicals by one-electron oxidation of HS{sup {minus}} ions. These radicals exist at pH values near 7 mainly as S{center_dot}{sup {minus}}. Their spontaneous decay results in the formation of the disulfide ion S{sub 2}{sup 2{minus}}. The further oxidation of disulfide either by S{center_dot}{sup {minus}} radicals or by the transition-metal ions yields higher polysulfide ions from which the homocyclic sulfur molecules S{sub 6}, S{sub 7}, and S{sub 8} are formed. In water these hydrophobic molecules form clusters which grow to droplets of liquid sulfur (sulfur sol). Depending on the composition of the aqueous phase, crystallization of the liquid sulfur as either {alpha}- or {beta}-S{sub 8} is rapid or delayed. Surfactants delay this solidification, while certain cations promote it. All these reactions are proposed to take place in desulfurization plants working by the Stretford, Sulfolin, Lo-Cat, SulFerox, or Bio-SR processes. In addition, the sulfur produced from sulfide by oxidizing sulfur bacteria is formed by the same mechanism, which now explains many observations made previously (including the formation of the byproducts thiosulfate, polythionates, and sulfate).

  8. Process for the production of sodium carbonate anhydrate

    NARCIS (Netherlands)

    Oosterhof, H.; Van Rosmalen, G.M.; Witkamp, G.J.; De Graauw, J.

    2000-01-01

    The invention is directed to a process for the production of sodium carbonate-anhydrate having a bulk density of at least 800 kg/m<3>, said process comprising: providing a suspension of solid sodium carbonate and/or solid sodium bicarbonate and/or solid double salts at least comprising one of

  9. Process and economic model of in-field heavy oil upgrading using aqueous pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Thorsness, C. B., LLNL

    1997-01-21

    A process and economic model for aqueous pyrolysis in-field upgrading of heavy oil has been developed. The model has been constructed using the ASPEN PLUS chemical process simulator. The process features cracking of heavy oil at moderate temperatures in the presence of water to increase oil quality and thus the value of the oil. Calculations with the model indicate that for a 464 Mg/day (3,000 bbl/day) process, which increases the oil API gravity of the processed oil from 13.5{degree} to 22.4{degree}, the required value increase of the oil would need to be at least $2.80/Mg{center_dot}{degree}API($0.40/bbl{center_dot}{degree}API) to make the process economically attractive. This level of upgrading has been demonstrated in preliminary experiments with candidate catalysts. For improved catalysts capable of having the coke make and increasing the pyrolysis rate, a required price increase for the oil as low as $1.34/Mg{center_dot}{degree}API ($0.21/bbl{center_dot}{degree}API)has been calculated.

  10. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    Science.gov (United States)

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. PMID:26469934

  11. 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.

  12. Error analysis of equilibrium studies for the almond shell activated carbon adsorption of Cr(VI) from aqueous solutions

    International Nuclear Information System (INIS)

    In this study, the preparation of activated carbon from almond shell with H2SO4 activation and its ability to remove toxic hexavalent chromium from aqueous solutions are reported. The influences of several operating parameters such as pH, particle size and temperature on the adsorption capacity were investigated. Adsorption of Cr(VI) is found to be highly pH, particle size and temperature dependent. Four adsorption isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich were used to analyze the equilibrium data. The Langmuir isotherm provided the best correlation for Cr(VI) onto the almond shell activated carbon (ASC). Adsorption capacity was calculated from the Langmuir isotherm as 190.3 mg/g at 323 K. Thermodynamic parameters were evaluated and the adsorption was endothermic showing monolayer adsorption of Cr(VI). Five error functions were used to treat the equilibrium data using non-linear optimization techniques for evaluating the fit of the isotherm equations. The highest correlation for the isotherm equations in this system was obtained for the Freundlich isotherm. ASC is found to be inexpensive and effective adsorbent for removal of Cr(VI) from aqueous solutions

  13. Sorption of mercury (II) and atrazine by biochar, modified biochars and biochar based activated carbon in aqueous solution.

    Science.gov (United States)

    Tan, Guangcai; Sun, Weiling; Xu, Yaru; Wang, Hongyuan; Xu, Nan

    2016-07-01

    Corn straw biochar (BC) was used as a precursor to produce Na2S modified biochar (BS), KOH modified biochar (BK) and activated carbon (AC). Experiments were conducted to compare the sorption capacity of these sorbents for aqueous Hg (II) and atrazine existed alone or as a mixture. In comparison to BC, the sorption capacity of BS, BK and AC for single Hg (II) increased by 76.95%, 32.12% and 41.72%, while that for atrazine increased by 38.66%, 46.39% and 47 times, respectively. When Hg (II) and atrazine coexisted in an aqueous solution, competitive sorption was observed on all these sorbents. Sulfur impregnation was an efficient way to enhance the Hg (II) removal due to the formation of HgS precipitate, and oxygen-containing functional groups on the sorbents also contributed to Hg (II) sorption. Activated carbon was the best sorbent for atrazine removal because of its extremely high specific surface area. PMID:27061260

  14. Comparison efficiency of both sonochemical and sonochemical/hydrogen peroxide processes forcyanide removal from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Reza Shokohi

    2009-01-01

    Full Text Available (Received 5 October, 2009 ; Accepted 23 December, 2009AbstractBackground and purpose: Cyanide is a species of high toxicity that is found mostly in industrial effluents such as electroplating, metal mining, metallurgy and metal cleaning processes. Entrance of it to existing environment contains a hazardous to health. The purpose of this study was to compare efficiency of both sonochemical and sonochemical / hydrogen peroxide processes for cyanide removal from aqueous solutions.Materials and methods: This study has been used from a productive set of 500w power ultrasound waves in of two frequencies 35 kHz and 130 kHz. Experiments were performed with different initial ratio 1/1, 1/3 and 1/5 and at initial cyanide concentrations varying from 2.5 to 75 mg/L. in this study, Effects of parameters such as pH; time, initial cyanide concentration, hydrogen peroxide/ cyanide and frequency on removal efficiency of mention processes have been studied.Results: The results of the study showed that the maximum removal efficiency of cyanide had been achieved to 74% by sonochemical process at frequency of 130 kHz, at time of 90 min, at pH of 11, at initial cyanide concentration of 2.5 mg/l and with initial ratio of 1/5. However in similar condition, removal efficiency of cyanide had been achieved to 85% by sonochemical/ hydrogen peroxide process.Conclusion: The results of the study showed that rates of cyanide degradation under different conditions had always been quite low, and also the rate of cyanide degradation was first high but it was later substantially reduced. Results of the study showed that efficiency of sonochemical/hydrogen peroxide process is more than of sonochemical process for cyanide removal from aqueous solutions. Also removal efficiency of cyanide has direct relationship with pH, frequency, hydrogen peroxide and time; however, it has reverse relationship with cyanide concentration for process.J Mazand Univ Med Sci 2009; 19(73: 60-67 (Persian.

  15. Apparatus and process for the surface treatment of carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  16. Bifunctional, Carbon-Free Nickel/Cobalt-Oxide Cathodes for Lithium-Air Batteries with an Aqueous Alkaline Electrolyte

    International Nuclear Information System (INIS)

    Highlights: • High activity bi-functional catalyst combination for ORR and OER . • An optimum ratio of high active bi-functional catalysts was found. • Novel electrodes without carbon to avoid carbon corrosion during OER mode. • EIS model for OER describes influence of a growing oxide layers. • Long-term test exhibited an excellent long-term stability over 1200 cycles. - Abstract: Lithium-air batteries with an aqueous alkaline electrolyte promise a very high practical energy density and capacity. These batteries are mainly limited by high overpotentials on the bifunctional cathode during charge and discharge. To reduce overpotentials the bifunctional cathode of such batteries must be improved significantly. Nickel is relatively inexpensive and has a good catalytic activity in alkaline media. Co3O4 was found to be a promising metal oxide catalyst for oxygen evolution in alkaline media but it has a low electronic conductivity. On the other hand since nickel has a good electronic conductivity Co3O4 can be added to pure nickel electrodes to enhance performance due to a synergetic effect. Due to the poor stability of carbon materials at high anodic potentials, gas diffusion electrodes were prepared without carbon to improve especially long-term stability. Gas diffusion electrodes were electrochemically investigated in a half cell. In addition, cyclic voltammogrametry (CV) and electrochemical impedance spectroscopy (EIS) were carried out. SEM was used for the physical and morphological investigations. Investigations showed that electrodes containing 20 wt.% Co3O4 exhibited the highest performance

  17. Utilization of activated carbon produced from fruit juice industry solid waste for the adsorption of Yellow 18 from aqueous solutions.

    Science.gov (United States)

    Angin, Dilek

    2014-09-01

    The use of activated carbon obtained from sour cherry (Prunus cerasus L.) stones for the removal of a basic textile dye, which is Yellow 18, from aqueous solutions at different contact times, pH values and solution temperatures was investigated. The surface area and micropore volume of chemically modified activated carbon were 1704 m(2) g(-1) and 0.984 cm(3) g(-1), respectively. The experimental data indicated that the adsorption isotherms were well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity was 75.76 mg g(-1) at 318 K. The adsorption kinetic of Yellow 18 obeys the pseudo-second-order kinetic model. The thermodynamic parameters were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 0.71-2.36 kJ/mol. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal of Yellow 18 from wastewater. PMID:24656549

  18. A low energy aqueous ammonia CO2 capture process

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Waseem Arshad, Muhammad; Blaker, Eirik Ask;

    2014-01-01

    The most pressing challenges regarding the use of ammonia for CO2 capture are the precipitation limitation and the energy penalty of solvent regeneration. Precipitation-free operation is a vital task since solids may cause the shutdown of the plant. Precipitation and slurry formation can be avoided...... by increasing temperature and L/G ratio but this leads to higher heat consumption, jeopardizing the economic feasibility. Here we developed, investigated, and optimized a novel CO2 capture process design using aqueous ammonia as solvent. The proposed configuration replaces the traditional stripper...... for solvent based CO2 capture with a thermal decomposition reactor. The overall energy penalty is reduced at the expense of introducing a solid handling section which consists of a saturation reactor, a crystallizer and a belt filter. The feasibility of the present approach is demonstrated by...

  19. Preparation and Characterization of M-Type Barium Ferrite Fibers via Aqueous Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    GONG Cairong; FAN Guoliang; SONG Chonglin; L(U) Gang

    2007-01-01

    BaFe12O19 fibers was prepared via an aqueous sol-gel process using Fe(OH)( HCOO)2 synthesized in laboratory and Ba(CH3COO)2 as the original materials and citrate as the chelate. The rheological behaviour of spinnable sol was characterized on rheometer, and the development of gel fibers to barium ferrite fibers was studied by IR, TG and XRD. Morphology observation of the fibers was given on SEM, and the diameter of the obtained fibers was between 5 and 10 μm corresponding to different additives. The additives affected the surface tension of the precursor sol which had close relation to the microstructure of fibers. Sucrose and hydroxyethylic cellulose could improve the surface tension while diethanolamine and hexadecylamine reduce that of the precursor sol. And using diethanolamine or hexadecylamine as an additive, well-structured BaFe12O19 fibers could be obtained.

  20. Preparation of silver nanoparticles by a non-aqueous sol-gel process.

    Science.gov (United States)

    Petit, Christophe T G; Alsulaiman, Muath S A; Lan, Rong; Mann, Gregory; Tao, Shanwen

    2013-08-01

    Using a non-aqueous sol-gel process with a direct calcination step in air after prior drying, silver nanoparticles with average size distribution ranging from 20 to 100 nm were synthesised. Studies in reduced atmosphere were also performed with mixed results, both in phase and particle size, as the samples were found to be mixed with an amorphous phase. In oxidising atmosphere, the temperature and dwelling time were found to be critical factors with the former playing a larger role than the latter. Optimally nanoparticles of silver are best prepared by direct calcination in air of the precursor gel at 250 degrees C for 1 hour. Compared to silver particles prepared by microemulsions, the particle size is larger due to the thermal treatment, which causes a growth of the silver particles. PMID:23882777

  1. Ox red-metric study of complex formation processes of manganese (II, III) in glycin aqueous solution

    International Nuclear Information System (INIS)

    Present article is devoted to ox red-metric study of complex formation processes of manganese (II, III) in glycin aqueous solution. The possibility of application of ox red-metric method for study of complex formation processes of manganese (II, III) was shown. The composition of complex compounds was determined.

  2. 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)

  3. In situ growth BaTiO3 nanocubes and their superlattice from an aqueous process

    Science.gov (United States)

    Dang, Feng; Mimura, Kenichi; Kato, Kazumi; Imai, Hiroaki; Wada, Satoshi; Haneda, Hajime; Kuwabara, Makoto

    2012-02-01

    Ordered aggregated BaTiO3 nanocubes with a narrow size distribution were obtained in an aqueous process by using bis(ammonium lactate) titanium dihydroxide (TALH) as Ti source in the presence of oleic acid and tert-butylamine. Kinetics of the formation of BaTiO3 nanocubes indicated that an in situ growth mechanism was dominant and the superlattice of nanocubes formed in situ through the growth of BaTiO3 nanoparticles in Ti-based hydrous gel. The size and morphology of nanocubes were controlled by tuning the concentration and molar ratio of surfactants. A novel growth model dependant on the structure of Ti precursor for the formation and morphology control of BaTiO3 nanocubes and their superlattice was demonstrated.Ordered aggregated BaTiO3 nanocubes with a narrow size distribution were obtained in an aqueous process by using bis(ammonium lactate) titanium dihydroxide (TALH) as Ti source in the presence of oleic acid and tert-butylamine. Kinetics of the formation of BaTiO3 nanocubes indicated that an in situ growth mechanism was dominant and the superlattice of nanocubes formed in situ through the growth of BaTiO3 nanoparticles in Ti-based hydrous gel. The size and morphology of nanocubes were controlled by tuning the concentration and molar ratio of surfactants. A novel growth model dependant on the structure of Ti precursor for the formation and morphology control of BaTiO3 nanocubes and their superlattice was demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11594h

  4. Optimization and orthogonal design of an ultrasonic-assisted aqueous extraction process for extracting chlorogenic acid from dry tobacco leaves

    Institute of Scientific and Technical Information of China (English)

    Martin Tongai Mazvimba; YU Ying; CUI Zhi-Qin; ZHANG Ying

    2012-01-01

    Processing parameters for heat reflux and ultrasonic-assisted extraction techniques were optimized.Optimal operating conditions,extraction solvents and extraction yields for both methods were established.Although methanol showed high extraction efficiency in heat reflux extraction,residual amounts of methanol caused adulteration of extracts.To circumvent this drawback,a novel ultrasonic-assisted aqueous extraction process was optimized and orthogonally designed to pave the way for replacing the toxic organic solvent,methanol with water.A new approach which utilizes fractional volumes of an extraction solvent was developed to minimize solvent consumption,improve chlorogenic acid solubility in water and enhance its aqueous extraction from dried tobacco leaves.Desired trajectories for the new ultrasonic assisted aqueous extraction process were found.

  5. Metal Oxide-Carbon Nanocomposites for Aqueous and Nonaqueous Supercapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I effort focuses on development of novel metal-oxide-carbon nanocomposites for application in pseudocapacitive...

  6. Optimization and Modeling of Hexavalent Chromium Removal from Aqueous Solution Via Adsorption on Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Mina Gholipour

    2011-09-01

    Full Text Available Hexavalent chromium and its derivatives are potential pollutant due to their mortal affects. Therefore, It is essential to remove these components from wastewaters before disposal. Adsorption can be effective and versatile method for removing of hexavalent chromium. In this article, removal of hexavalent chromium via adsorption on multiwalled carbon nanotubes was investigated as a function of adsorbent dosage, initial solution pH, initial Cr(VI concentrations, contact time and temperature. The batch experiments were conducted at 3 different temperatures (17, 27 and 37ºC and shows that Cr (VI removal obeys pseudo-second order rate equation. Rate constant (K values in 3 temperatures, pre-exponential factor and adsorption activation energy (E was also obtained. The sorption data fitted well with Freundlich isotherm adsorption model. Thermodynamic parameters such as Gibbs free energy (ΔGº, enthalpy (ΔHº and entropy (ΔSº for Cr(VI adsorption were estimated and Results suggest that the adsorption process is a spontaneous and endothermic.

  7. Amorphous carbon contamination monitoring and process optimization for single-walled carbon nanotube integration

    International Nuclear Information System (INIS)

    We detail the monitoring of amorphous carbon deposition during thermal chemical vapour deposition of carbon nanotubes and propose a contamination-less process to integrate high-quality single-walled carbon nanotubes into micro-electromechanical systems. The amorphous content is evaluated by confocal micro-Raman spectroscopy and by scanning/transmission electron microscopy. We show how properly chosen process parameters can lead to successful integration of single-walled nanotubes, enabling nano-electromechanical system synthesis

  8. Conversion of phosphogypsum to potassium sulfate and calcium carbonate in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ennaciri Y.

    2013-09-01

    Full Text Available The dissociation of the phosphogysum by the liquid route which is the object of our work, is most appropriate and little expensive. Indeed, it leads to materials of direct application. The present work has for objective to study the decomposition of the phosphogypsum by the soft chemistry into valuable products such as K2SO4 and CaCO3. K2SO4 is a fertilizer which is highly recommended in the field of the agriculture, while CaCO3 can be used in the fields of the industry (cement and the environment. According to the obtained results, we notice that the decomposition of the phosphogypsum in aqueous solution is very workable, reproducible, inexpensive and it is an ecologically interesting reaction. This reaction is made at room temperature and in aqueous environment, by giving two valuable products K2SO4 and CaCO3. The reaction is total after one hour and a half.

  9. Ultradry Carbon Dioxide-in-Water Foams with Viscoelastic Aqueous Phases.

    Science.gov (United States)

    Xue, Zheng; Worthen, Andrew J; Da, Chang; Qajar, Ali; Ketchum, Isaiah Robert; Alzobaidi, Shehab; Huh, Chun; Prodanović, Maša; Johnston, Keith P

    2016-01-12

    For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high-pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volume fractions ϕ of 0.95 to 0.98; the viscosity of these ultradry foams increased by up to 3-4-fold, reaching more than 100 cP relative to foams formed with conventional low viscosity aqueous phases. The foam morphology consisted of fine ∼20 μm polyhedral-shaped CO2 bubbles that were stable for hours. The wormlike micelles were formed by mixing anionic sodium lauryl ether sulfate (SLES) with salt and a protonated cationic surfactant, as shown by cryogenic transmission electron microscopy (cryo-TEM) and large values of the zero-shear viscosity and the dynamic storage and loss moduli. With the highly viscous continuous aqueous phases, the foam lamella drainage rates were low, as corroborated by confocal microscopy. The preservation of viscous thick lamellae resulted in lower rates of Ostwald ripening relative to conventional foams as shown by high-pressure optical microscopy. The ability to stabilize viscous ultra high internal phase foams is expected to find utility in various practical applications, including nearly "waterless" fracturing fluids for recovery of oil and gas in shale, offering the possibility of a massive reduction in the amount of wastewater. PMID:26666311

  10. Reaction Mechanism and Kinetics of Aqueous Solutions of Primary and Secondary Alkanolamines and Carbon Dioxide

    OpenAIRE

    BAVBEK, Olgac; ALPER, Erdoğan

    1999-01-01

    The mechanism and kinetics of the reaction between aqueous solutions of CO2 and the alkanolamines 1-amino-2-propanol, 3-amino-1-propanol,2-methyl aminoethanol and 2-ethyl aminoethanol were investigated using a stopped flow technique. It was found that the reaction orders according to power law kinetics were between 1.1 and 2.0, depending on the alkanolamine and the concentration ranges investigated. This fractional order was therefore considered to be further evidence that carbamate ...

  11. Experimental measurements of carbon dioxide solubility in aqueous tetra-n-butylammonium bromide solutions

    International Nuclear Information System (INIS)

    Highlights: • We report experimental CO2 solubility data in aqueous tetra-n-butylammonium bromide. • The absolute gravimetric technique was used for the CO2 solubility measurements. • CO2 solubility in pure water agrees with the literature data. - Abstract: In this paper, we report the absolute measurements of CO2 solubility in aqueous tetra-n-butylammonium bromide (TBAB) solution. The measurement range was 0.2 MPa < P < 4 MPa, 286.15 K < T < 298.15 K, with 0 (pure water) < wTBAB < 0.4, where P, T, and wTBAB denote the pressure, temperature, and mass fraction of TBAB in the aqueous feed solutions, respectively. These thermodynamic conditions are outside the hydrate formation region. We evaluated salting-in and -out effects based on the experimental data, and confirmed that the CO2 salting-out effect of TBAB clearly appeared at T = 292 K with wTBAB < 0.32 and the salting-in effect may exist for P > 3 MPa and T > 292 K with wTBAB ⩾ 0.4 mass fraction of TBAB

  12. A non-aqueous reduction process for purifying ¹⁵³Gd produced in natural europium targets.

    Science.gov (United States)

    Johnsen, Amanda M; Soderquist, Chuck Z; McNamara, Bruce K; Fisher, Darrell R

    2013-12-01

    Gadolinium-153 is a low-energy gamma-emitter used in nuclear medicine imaging quality assurance. Produced in nuclear reactors using natural Eu₂O₃ targets, ¹⁵³Gd is radiochemically separated from europium isotopes by europium reduction. However, conventional aqueous europium reduction produces hydrogen gas, a flammability hazard in radiological hot cells. We altered the traditional reduction method, using methanol as the process solvent to nearly eliminate hydrogen gas production. This new, non-aqueous reduction process demonstrates greater than 98% europium removal and gadolinium yields of 90%. PMID:24001618

  13. Processes for reducing NHS carbon footprint.

    Science.gov (United States)

    2007-08-01

    NHS Trust boards face challenging targets for cutting carbon emissions from new and existing facilities. Spirax Sarco's Murdo Macdonald looks at the help available and some of the latest examples of good practice in steam systems for hospital heating and hot water. PMID:17847881

  14. Processes for preparing carbon fibers using gaseous sulfur trioxide

    Science.gov (United States)

    Barton, Bryan E.; Lysenko, Zenon; Bernius, Mark T.; Hukkanen, Eric J.

    2016-01-05

    Disclosed herein are processes for preparing carbonized polymers, such as carbon fibers, comprising: sulfonating a polymer with a sulfonating agent that comprises SO.sub.3 gas to form a sulfonated polymer; treating the sulfonated polymer with a heated solvent, wherein the temperature of said solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 500-3000.degree. C.

  15. 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

  16. Adsorption of phenol from aqueous solution by a hierarchical micro-nano porous carbon material

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with...

  17. Process to minimize cracking of pyrolytic carbon coatings

    International Nuclear Information System (INIS)

    The object of this invention is to provide a process which significantly improves upon prior techniques of producing fuel microspheres by producing carbon coated fuel particles with a small percentage of cracked particles and with reduced stress levels within the coated layers. This is accomplished by annealing the coated particles immediately after deposition of the dense pyrolytic carbon layer. (auth)

  18. Explorations of soil microbial processes driven by dissolved organic carbon

    NARCIS (Netherlands)

    Straathof, A.L.

    2015-01-01

    Explorations of soil microbial processes driven by dissolved organic carbon Angela L. Straathof June 17, 2015, Wageningen UR ISBN 978-94-6257-327-7 Abstract Dissolved organic carbon (DOC) is a complex, heterogeneous mixture of C compounds which, as

  19. Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

    Science.gov (United States)

    Stegen, James C.; Fredrickson, James K.; Wilkins, Michael J.; Konopka, Allan E.; Nelson, William C.; Arntzen, Evan V.; Chrisler, William B.; Chu, Rosalie K.; Danczak, Robert E.; Fansler, Sarah J.; Kennedy, David W.; Resch, Charles T.; Tfaily, Malak

    2016-01-01

    Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater–surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater–surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds. PMID:27052662

  20. Non-aqueous carbon black suspensions for lithium-based redox flow batteries: rheology and simultaneous rheo-electrical behavior.

    Science.gov (United States)

    Youssry, Mohamed; Madec, Lénaïc; Soudan, Patrick; Cerbelaud, Manuella; Guyomard, Dominique; Lestriez, Bernard

    2013-09-14

    We report on the rheological and electrical properties of non-aqueous carbon black (CB) suspensions at equilibrium and under steady shear flow. The smaller the primary particle size of carbon black is, the higher the magnitude of rheological parameters and the conductivity are. The electrical percolation threshold ranges seem to coincide with the strong gel rather than the weak gel rheological threshold ones. The simultaneous measurements of electrical properties under shear flow reveal the well-known breaking-and-reforming mechanism that characterises such complex fluids. The small shear rate breaks up the network into smaller agglomerates, which in turn transform into anisometric eroded ones at very high shear rates, recovering the network conductivity. The type of carbon black, its concentration range and the flow rate range are now precisely identified for optimizing the performance of a redox flow battery. A preliminary electrochemical study for a composite anolyte (CB/Li4Ti5O12) at different charge-discharge rates and thicknesses is shown. PMID:23892887

  1. Carbon nanofibers with radially grown graphene sheets derived from electrospinning for aqueous supercapacitors with high working voltage and energy density

    Science.gov (United States)

    Zhao, Lei; Qiu, Yejun; Yu, Jie; Deng, Xianyu; Dai, Chenglong; Bai, Xuedong

    2013-05-01

    Improvement of energy density is an urgent task for developing advanced supercapacitors. In this paper, aqueous supercapacitors with high voltage of 1.8 V and energy density of 29.1 W h kg-1 were fabricated based on carbon nanofibers (CNFs) and Na2SO4 electrolyte. The CNFs with radially grown graphene sheets (GSs) and small average diameter down to 11 nm were prepared by electrospinning and carbonization in NH3. The radially grown GSs contain between 1 and a few atomic layers with their edges exposed on the surface. The CNFs are doped with nitrogen and oxygen with different concentrations depending on the carbonizing temperature. The supercapacitors exhibit excellent cycling performance with the capacity retention over 93.7% after 5000 charging-discharging cycles. The unique structure, possessing radially grown GSs, small diameter, and heteroatom doping of the CNFs, and application of neutral electrolyte account for the high voltage and energy density of the present supercapacitors. The present supercapacitors are of high promise for practical application due to the high energy density and the advantages of neutral electrolyte including low cost, safety, low corrosivity, and convenient assembly in air.

  2. Synthesis and application of highly active dithiooxamide fictionalised multi-walled carbon nanotubes toward mercury removal from aqueous solution

    International Nuclear Information System (INIS)

    Highly sensitive and accurate method has been applied for removal of toxic mercury(II) ions in aqueous solution, using synthesized nanosorbent. Determination of mercury(II) was carried out by flame atomic absorption spectrometer. A nanosorbent MWCNT was synthesized by the reaction of dithiooxamide with functionalized multi-walled carbon nanotubes. Initially, the surface of the multi-walled carbon nanotubes was oxidized by a mixture of nitric and sulfuric acids and then was functionalized using thionyl chloride. The ligand has been attached to the multi-walled carbon nanotubes in a somewhat shorter time and lower temperature than previous reported methods. The sorbent was characterized by Fourier transmission infrared and scanning electron microscopy. In this research, the effect of different parameters in removal of mercury(II) ions by nanosorbent, such as, pH, amount of nanosorbent, time and concentration of Hg(II), was investigated. Experiments show that the new MWCNT with loading amount of 1.02 mmol g-1 is a powerful sorbent for removing the Hg(II) ions from water. (author)

  3. Process for Making Carbon-Carbon Turbocharger Housing Unit for Intermittent Combustion Engines

    Science.gov (United States)

    Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    1999-01-01

    An improved. lightweight, turbine housing unit for an intermittent combustion reciprocating internal combustion engine turbocharger is prepared from a lay-up or molding of carbon-carbon composite materials in a single-piece or two-piece process. When compared to conventional steel or cast iron, the use of carbon-carbon composite materials in a turbine housing unit reduces the overall weight of the engine and reduces the heat energy loss used in the turbo-charging process. This reduction in heat energy loss and weight reduction provides for more efficient engine operation.

  4. Voltametric study of formic and dihydroxy malonic acids on platinum for the definition of a process for the electrolytic destruction of carboxylic acids in radioactive aqueous effluents

    International Nuclear Information System (INIS)

    To limit the amount of nuclear glasses generated by the treatment of the degraded solvent from the PUREX process for reprocessing of nuclear fuels, by solutions of sodium carbonate and caustic soda, it is planned to exploit the complexing power of certain carboxylic acids to return the metallic cations to the aqueous phase. The concept of this new treatment of the solvent by 'substitution' reagents demands a process for the decomposition of these reagents, especially to CO2. The investigation of the electrochemical behaviour, on platinum, of a substance selected as a model for understanding the interfacial mechanisms (HCOOH), and of dihydroxy malonic acid, revealed two distinct electro-poisoning processes: one is due to the adsorption of CO on the surface sites of platinum, and the second to the formation of a passivating layer of P†O. The application of 20 kHz ultrasonic flux in the neighbourhood of the platinum / aqueous formic acid solution interface also appears to cause a change in the superficial structure of the electrode used, in a direction that favours the decomposition of this compound. To overcome problems of poisoning of the platinum surface, aqueous solutions of formic, dihydroxy malonic and oxalic acids were electrolysed, in a cell without diaphragm, by applying voltage and current ranges, at levels adapted to each of the species. It is necessary to bring the working electrode to a higher potential than the oxidation potential for formic acid, and to a lower potential for dihydroxy malonic and oxalic acids. The frequent modifications of the electrode potentials helped to achieve quantitative destruction of these species, to CO2 (and to water) with an electrochemical efficiency approaching 100 %. This wet oxidation process also offers the advantage of not raising the energy potential of the effluents to be treated, because it takes place in mild conditions (ambient temperature and pressure). (author). 131 refs., 90 figs., 48 tabs

  5. Enrichment and Fundamental Optical Processes of Armchair Carbon Nanotubes

    Science.gov (United States)

    Haroz, Erik H.

    The armchair variety of single-wall carbon nanotubes (SWCNTs) is the only nanotube species that behaves as a metal with no electronic band gap and massless carriers, making them ideally suited to probe fundamental questions of many-body physics of one-dimensional conductors as well as to serve in applications such as highcurrent power transmission cables. However, current methods of nanotube synthesis produce bulk material comprising of a mixture of nanotube lengths, diameters, wrapping angles, and electronic types due to the inability to control the growth process at the nanometer level. As a result, measurements of as-grown SWCNTs produce a superposition of electrical and optical responses from multiple SWCNT species. This thesis demonstrates production of aqueous suspensions composed almost entirely of armchair SWCNTs using a post-synthesis separation method employing density gradient ultracentrifugation (DGU) to separate different SWCNT types based on their mass density and surfactant-specific interactions. Resonant Raman spectroscopy determines the relative abundances of each nanotube species, before and after DGU, by measuring the integrated intensity of the radial breathing mode, the diameter-dependent radial vibration of the SWCNT perpendicular to its main axis, and quantifies the degree of enrichment of bulk nanotube samples to exclusively armchair tubes. Raman spectroscopy of armchair-enriched samples of the G-band mode, which is composed of longitudinal (G-) and circumferential (G+) vibrations oscillating parallel and perpendicular to the tube axis, shows that the G- peak, long-held to be an indicator for the presence of metallic SWCNTs, appears only when electronic resonance with narrow-gap semiconducting SWCNTs occurs and shows only the G+ component in spectra containing only armchair species. Finally, by combining optical absorption measurements with nanotube composition as determined earlier via Raman scattering, peak fitting of absorption spectra

  6. Metal Oxide-Carbon Nanocomposites for Aqueous and Nonaqueous Supercapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Technology Transfer Phase 2 effort focuses on development of a supercapacitor energy storage device based on novel metal oxide-carbon...

  7. Elephant Moraine 96029, a very mildly aqueously altered and heated CM carbonaceous chondrite: Implications for the drivers of parent body processing

    Science.gov (United States)

    Lee, Martin R.; Lindgren, Paula; King, Ashley J.; Greenwood, Richard C.; Franchi, Ian A.; Sparkes, Robert

    2016-08-01

    Elephant Moraine (EET) 96029 is a CM carbonaceous chondrite regolith breccia with evidence for unusually mild aqueous alteration, a later phase of heating and terrestrial weathering. The presence of phyllosilicates and carbonates within chondrules and the fine-grained matrix indicates that this meteorite was aqueously altered in its parent body. Features showing that water-mediated processing was arrested at a very early stage include a matrix with a low magnesium/iron ratio, chondrules whose mesostasis contains glass and/or quench crystallites, and a gehlenite-bearing calcium- and aluminium-rich inclusion. EET 96029 is also rich in Fe,Ni metal relative to other CM chondrites, and more was present prior to its partial replacement by goethite during Antarctic weathering. In combination, these properties indicate that EET 96029 is one of the least aqueously altered CMs yet described (CM2.7) and so provides new insights into the original composition of its parent body. Following aqueous alteration, and whilst still in the parent body regolith, the meteorite was heated to ∼400-600 °C by impacts or solar radiation. Heating led to the amorphisation and dehydroxylation of serpentine, replacement of tochilinite by magnetite, loss of sulphur from the matrix, and modification to the structure of organic matter that includes organic nanoglobules. Significant differences between samples in oxygen isotope compositions, and water/hydroxyl contents, suggests that the meteorite contains lithologies that have undergone different intensities of heating. EET 96029 may be more representative of the true nature of parent body regoliths than many other CM meteorites, and as such can help interpret results from the forthcoming missions to study and return samples from C-complex asteroids.

  8. Excess heat production by the electrolysis of an aqueous potassium carbonate electrolyte and the implications for cold fusion

    International Nuclear Information System (INIS)

    This paper reports that according to a novel atomic model, the predominant source of heat of the phenomenon called cold fusion is the electrocatalytically induced reaction whereby hydrogen atoms undergo transitions to quantized energy levels of lower energy than the conventional ground state. These lower energy states correspond to fractional quantum numbers. The hydrogen electronic transition requires the presence of an energy hole of ∼27.21 eV provided by electrocatalytic reactants (such as Pd2+/Li+, Ti2+, or K+/K+ and results in shrunken atoms analogous to muonic atoms. In the case of deuterium, fusion reactions of shrunken atoms predominantly yielding tritium are possible. Calorimetry of pulsed current and continuous electrolysis of aqueous potassium carbonate (K+/K+ electrocatalytic couple) at a nickel cathode is performed in single-cell dewar calorimetry cells. Excess power out exceeded input power by a factor of >37

  9. Highly selective hydrogenation of phenol and derivatives over a Pd@carbon nitride catalyst in aqueous media.

    Science.gov (United States)

    Wang, Yong; Yao, Jia; Li, Haoran; Su, Dangsheng; Antonietti, Markus

    2011-03-01

    Cyclohexanone is an important intermediate in the manufacture of polyamides in chemical industry, but direct selective hydrogenation of phenol to cyclohexanone under mild conditions is a challenge. We report here a catalyst made of Pd nanoparticles supported on a mesoporous graphitic carbon nitride, Pd@mpg-C(3)N(4), which was shown to be highly active and promoted the selective formation of cyclohexanone under atmospheric pressure of hydrogen in aqueous media without additives. Conversion of 99% and a selectivity higher than 99% were achieved within 2 h at 65 °C. The reaction can be accelerated at higher temperature, but even at room temperature, 99% conversion and 96% selectivity could still be obtained. The generality of the Pd@mpg-C(3)N(4) catalyst for this reaction was demonstrated by selective hydrogenation of other hydroxylated aromatic compounds with similar performance. PMID:21294506

  10. Corrosion behavior of aluminum doped diamond-like carbon thin films in NaCl aqueous solution.

    Science.gov (United States)

    Khun, N W; Liu, E

    2010-07-01

    Aluminum doped diamond-like carbon (DLC:Al) thin films were deposited on n-Si(100) substrates by co-sputtering a graphite target under a fixed DC power (650 W) and an aluminum target under varying DC power (10-90 W) at room temperature. The structure, adhesion strength and surface morphology of the DLC:Al films were characterized by X-ray photoelectron spectroscopy (XPS), micro-scratch testing and atomic force microscopy (AFM), respectively. The corrosion performance of the DLC:Al films was investigated by means of potentiodynamic polarization testing in a 0.6 M NaCl aqueous solution. The results showed that the polarization resistance of the DLC:Al films increased from about 18 to 30.7 k(omega) though the corrosion potentials of the films shifted to more negative values with increased Al content in the films. PMID:21128496

  11. Removal of Uranium and Associated Contaminants from Aqueous Solutions Using Functional Carbon Nanotubes-Sodium Alginate Conjugates

    Directory of Open Access Journals (Sweden)

    Hussein Allaboun

    2016-02-01

    Full Text Available Synthesis of hydrophilic/hydrophobic beads from functional carbon nanotubes (CNTs conjugated with sodium alginate was investigated. Glutaraldehyde was used as a coupling agent and Ca2+ as a crosslinking agent. The formed conjugate comprises two-dimensional sheets of sodium alginate bounded to long tufts of functional CNT tails of micro-size geometry. Detailed characterization of the conjugates was performed using thermogravimetric analysis (TGA and its first derivative (DTG, Fourier transform infrared (FTIR, and scanning electron microscope (SEM techniques. Different ratios of the conjugate were successfully prepared and used as biodegradable environmentally friendly sorbents. Removal of U6+, V3+, Cr3+, Mo3+, Pb2+, Mn2+, Cu2+, Ti4+ and Ni2+ from aqueous solutions using the synthesized biosorbent was experimentally demonstrated. Maximum metal uptake of 53 mg/g was achieved using the % Functional CNTs = 33 sample.

  12. Kinetics of the Removal of Chromium Complex Dye from Aqueous Solutions Using Activated Carbons and Polymeric Adsorbent

    Directory of Open Access Journals (Sweden)

    Eglė Kazlauskienė

    2011-04-01

    Full Text Available The kinetics of the removal of chromium complex dye (Lanasyn Navy M-DNL from aqueous solutions using polymeric adsorbent Macronet MN 200 (MN 200 as an alternative option for activated carbon Norit RB 0.8 CC (AC was studied in the batch system. The residual colour of dye solution treated with AC or MN 200 strongly depends on solution pH with lower values at acidic pH when a positively charged surface net is favourable for the adsorption of the dye anion. The removal of dye using MN 200 was found relatively higher than that using AC. The pseudo-second order and intraparticle diffusion models agreed well with experimental data. The parameters of these models were studied as a function of temperature and adsorbent nature.Article in Lithuanian

  13. Synthesis and electrochemical properties of Li-rich spinel type LiMn2O4 powders by spray pyrolysis using aqueous solution of manganese carbonate

    International Nuclear Information System (INIS)

    Research highlights: → The rechargeable capacity and cycle performance of the cathode for lithium ion battery were significantly improved by using Li-rich LiMn2O4 powders derived from spray pyrolysis. → When manganese carbonate is used as a starting material, the industrial problem in the spray pyrolysis which the toxic gas is discharged in the powders production is overcome. Therefore, this powder preparation method is effective for the powder production of other metal oxide from liquid phase as the clean process without the toxic and corrosive gases. → It is clear that Li-rich LiMn2O4 cathode exhibits excellent cycle stability superior to metal doped LiMn2O4. → Li1.09Mn1.91O4 cathode exhibits also excellent cycle stability without the doping of foreign metal (Al, Cr , Mg, etc.) reported in past. - Abstract: Li-rich lithium manganese oxide (Li1.09Mn1.91O4) powders were prepared by spray pyrolysis using an aqueous solution of manganese carbonate. The aqueous solution, in which manganese carbonate was uniformly dispersed by a surfactant, was used as the starting solution. As observed by scanning electron microscopy, Li1.09Mn1.91O4 had spherical morphology with a porous microstructure and consisted of primary particles. Powder X-ray diffraction analysis revealed that the crystal phase of the Li1.09Mn1.91O4 powders was in good agreement with the spinel phase. Inductively coupled plasma analysis showed that the molar ratio of Li and Mn in the Li1.09Mn1.91O4 powders was 1.09:1.90. Through electrochemical measurements, the initial discharge capacity of a Li1.09Mn1.91O4 cathode was found to be 107 mAh/g at 1 C (99% retention after 100 cycles) and 91 mAh/g at 10 C (93% retention after 100 cycles). The retention ratio of discharge capacity remained greater than 90%, although capacity loss was observed up to 20 cycles. The Li1.09Mn1.91O4 cathode derived from carbonate solution had excellent cycling stability in comparison with the LiMn2O4 cathode derived from nitrate

  14. Combined advanced oxidation and biological treatment processes for the removal of pesticides from aqueous solutions

    International Nuclear Information System (INIS)

    Advanced oxidation processes were combined with biological treatment processes in this study to remove both pesticides and then the COD load from aqueous solutions. It was found that O3 and O3/UV oxidation systems were able to reach 90 and 100%, removal of the pesticide Deltamethrin, respectively, in a period of 210 min. The use of O3 combined with UV radiation enhances pesticides degradation and the residual pesticide reaches zero in the case of Deltamethrin. The combined O3/UV system can reduce COD up to 20% if the pH of the solution is above 4. Both pesticide degradation and COD removal in the combined O3/UV system follow the pseudo-first-order kinetics and the parameters of this model were evaluated. The application of the biological treatment to remove the bulk COD from different types of feed solution was investigated. More than 95% COD removal was achieved when treated wastewater by the O3/UV system was fed to the bioreactor. The parameters of the proposed Grau model were estimated

  15. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    Science.gov (United States)

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. PMID:25585639

  16. Removal of Zn(II) from dilute aqueous solutions and radioactive process wastewater by foam separation

    International Nuclear Information System (INIS)

    Ion, precipitate and adsorbing colloid flotations of zinc(II) from dilute aqueous solutions have been investigated over a wide pH range using the anionic surfactant Aerosol OT or the cationic collector cetyl pyridinium chloride. In case of adsorbing colloid flotation (ACF) iron oxyhydroxide and aluminium hydroxide were used, either separately or together, as coprecipitants. The precipitate flotation curves were compared with the corresponding theoretical one calculated from the data published for Zn(II) hydrolysis. In addition to the effect of pH on the percent removal the effects of collector concentration, ionic strength, bubbling time and metal ion concentration were investigated and the optimum conditions were established. High removals could be achieved especially with ACF. The results obtained are discussed with respect to the chemical state of zinc, the ionization behaviour of the collectors and properties of the coprecipitants. The developed ACF process was applied to the removal of 65Zn from radioactive process wastewater. (author). 45 refs., 6 figs., 4 tabs

  17. Aqueous Processing of Atmospheric Organic Particles in Cloud Water Collected via Aircraft Sampling

    Energy Technology Data Exchange (ETDEWEB)

    Boone, Eric J.; Laskin, Alexander; Laskin, Julia; Wirth, Christopher; Shepson, Paul B.; Stirm, Brian H.; Pratt, Kerri A.

    2015-07-21

    Cloud water and below-cloud atmospheric particle samples were collected onboard a research aircraft during the Southern Oxidant and Aerosol Study (SOAS) over a forested region of Alabama in June 2013. The organic molecular composition of the samples was studied to gain insights into the aqueous-phase processing of organic compounds within cloud droplets. High resolution mass spectrometry with nanospray desorption electrospray ionization and direct infusion electrospray ionization were utilized to compare the organic composition of the particle and cloud water samples, respectively. Isoprene and monoterpene-derived organosulfates and oligomers were identified in both the particles and cloud water, showing the significant influence of biogenic volatile organic compound oxidation above the forested region. While the average O:C ratios of the organic compounds were similar between the atmospheric particle and cloud water samples, the chemical composition of these samples was quite different. Specifically, hydrolysis of organosulfates and formation of nitrogen-containing compounds were observed for the cloud water when compared to the atmospheric particle samples, demonstrating that cloud processing changes the composition of organic aerosol.

  18. PERFORMANCE EVALUATION OF ELECTROCOAGULATION PROCESS FOR DIAZINON REMOVAL FROM AQUEOUS ENVIRONMENTS BY USING IRON ELECTRODES

    Directory of Open Access Journals (Sweden)

    E. Bazrafshan, A. H. Mahvi, S. Nasseri, M. Shaieghi

    2007-04-01

    Full Text Available The present study investigates the removal of pesticide by electrocoagulation process. A glass tank in 1.56 L volume with four iron plate electrodes was used to perform the experiments. The electrodes connected to a DC power supply (bipolar mode. The tank was filled with synthetic wastewater were which contained diazinon pesticide in concentration of 10, 50 and 100 mg/L. The percent of diazinon removal was measured at pH= 3, 7 and 10 and in electric potential range of 20-40V by thin layer chromatography method. The results indicated that initial concentration of diazinon can affect efficiency removal and for higher concentrations of diazinon, higher electrical potential or more reaction time is needed. The results showed that for a given time, the removal efficiency increased significantly with increase of voltage. The highest electrical potential (40V produced the quickest treatment with >99% diazinon reduction occurring after 60 min. The final pH for iron electrodes was always higher than initial pH. Finally it can be concluded that electrocoagulation process (using iron electrodes is a reliable, efficient and cost-effective method for removal of diazinon from aqueous environments, especially designed for pH=3 and voltage=40V.

  19. Optimizing Electrocoagulation Process for the Removal of Nitrate From Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Dehghani

    2016-01-01

    Full Text Available Background High levels of nitrate anion are frequently detected in many groundwater resources in Fars province. Objectives The present study aimed to determine the removal efficiency of nitrate from aqueous solutions by electrocoagulation process using aluminum and iron electrodes. Materials and Methods A laboratory-scale batch reactor was conducted to determine nitrate removal efficiency using the electrocoagulation method. The removal of nitrate was determined at pH levels of 3, 7, and 11, different voltages (15, 20, and 30 V, and operation times of 30, 60, and 75 min, respectively. Data were analyzed using the SPSS software version 16 (Chicago, Illinois, USA and Pearson’s correlation coefficient was used to analyze the relationship between the parameters. Results Results of the present study showed that the removal efficiency was increased from 27% to 86% as pH increased from 3 to 11 at the optimal condition of 30 V and 75 min operation time. Moreover, by increasing the reaction time from 30 V to 75 min the removal efficiency was increased from 63% to 86%, respectively (30 V and pH = 11. Pearson’s correlation analysis showed that there was a significant relationship between removal efficiency and voltage and reaction time as well (P < 0.01. Conclusions In conclusion, the electrocoagulation process can be used for removing nitrate from water resources because of high efficiency, simplicity, and relatively low cost.

  20. Preparation of carbon microspheres decorated with silver nanoparticles and their ability to remove dyes from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qingchun [Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Wu, Qingsheng, E-mail: qswu@tongji.edu.cn [Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)

    2015-02-11

    Highlights: • Carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared. • AgNP-CMSs show not only rapid and high adsorption capacity to methylene blue (MB) in water, but also excellent reusability. • It exhibits photocatalytic activity to Rhodamine B as well as MB under visible light. • The adsorption is from the ionic interactions but not the π–π conjugations. • The origin of photocatalysis is a surface plasmon resonance effect of AgNP on CMSs. - Abstract: Solid, but not hollow or porous, carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared from silver nitrate and CMSs by a redox reaction at room temperature. The CMSs and AgNP-CMSs were characterized using X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and UV–vis spectrophotometry. Though with non-high specific surface area, the AgNP-CMSs exhibited a high adsorption capacity toward methylene blue (MB) in an aqueous solution. The AgNP-CMSs were able to remove all the MB from a solution of 30 mg/L MB in water within 1 min when the adsorbent concentration was 0.12 g/L. The AgNP-CMSs also exhibited good adsorption and photocatalytic activity in the decomposition of aqueous Rhodamine B as well as MB under visible light. FTIR was used to examine the interaction between AgNP-CMSs and MB, and the spectrum and more extra experiments suggest ionic interactions between cationic dyes and the negatively charged groups can be formed but not the presence of abundant π–π conjugations between dye molecules and the aromatic rings. The origin of the photocatalytic activity of AgNP-CMSs was attributed to a surface plasmon resonance (SPR) effect of the silver nanoparticles on the CMSs.

  1. Process synthesis and optimization for the production of carbon nanostructures

    International Nuclear Information System (INIS)

    A swirled fluidized bed chemical vapour deposition (SFCVD) reactor has been manufactured and optimized to produce carbon nanostructures on a continuous basis using in situ formation of floating catalyst particles by thermal decomposition of organometallic ferrocene. During the process optimization, carbon nanoballs were produced in the absence of a catalyst at temperatures higher than 1000 0C, while carbon nanofibres, single-walled carbon nanotubes, helical carbon nanotubes, multi-walled carbon nanotubes (MWCNTs) and carbon nanofibres (CNFs) were produced in the presence of a catalyst at lower temperatures of between 750 and 900 0C. The optimum conditions for producing carbon nanostructures were a temperature of 850 0C, acetylene flow rate of 100 ml min-1, and acetylene gas was used as the carbon source. All carbon nanostructures produced have morphologies and diameters ranging from 15 to 200 nm and wall thicknesses between 0.5 and 0.8 nm. In comparison to the quantity of MWCNTs produced with other methods described in the literature, the SFCVD technique was superior to floating catalytic CVD (horizontal fixed bed) and microwave CVD but inferior to rotary tube CVD.

  2. The interaction of pH, pore solution composition and solid phase composition of carbonated blast furnace slag cement paste activated with aqueous sodium monofluorophosphate

    OpenAIRE

    Kempl, J.; Copuroglu,O.

    2015-01-01

    Blast Furnace Slag (BFS) is a waste product of industrial steel production and a common additive in the cement industry in Northern European countries. However, cementitious materials made from slag-rich cement, particularly CEM III /B, are very susceptible to carbonation. Recent investigations have shown that the surface application of aqueous sodium monofluorophosphate (Na-MFP) as pre- and post-carbonation treatment can improve the surface durability of cementitious materials with a high BF...

  3. 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...

  4. Potentiometric and spectrophotometric study of the stability of magnesium carbonate and bicarbonate ion pairs to 150 °C and aqueous inorganic carbon speciation and magnesite solubility

    Science.gov (United States)

    Stefánsson, Andri; Bénézeth, Pascale; Schott, Jacques

    2014-08-01

    The formation constants of magnesium bicarbonate and carbonate ion pairs have been experimentally determined in dilute hydrothermal solutions to 150 °C. Two experimental approaches were applied, potentiometric acid-base titrations at 10-60 °C and spectrophotometric pH measurements using two pH indicators, 2-naphthol and 4-nitrophenol, at 25 and 80-150 °C. At a given temperature, the first and second ionization constants of carbonic acid (K1, K2) and the ion pair formation constants for MgHCO3+(aq) (KMgHCO3+) and MgCO3(aq) (KMgCO3) were simultaneously fitted to the data. Results of this study compare well with previously determined values of K1 and K2. The formation constants of MgHCO3+(aq) and MgCO3(aq) ion pairs increased significantly with increasing temperature, with values of logKMgHCO3+ = 1.14 and 1.75 and of logKMgCO3 = 2.86 and 3.48 at 10 °C and 100 °C, respectively. These ion pairs are important aqueous species under neutral to alkaline conditions in moderately dilute to concentrated Mg-containing solutions, with MgCO3(aq) predominating over CO32-(aq) in solutions at pH >8. The predominance of magnesium carbonate over carbonate is dependent on the concentration of dissolved magnesium and the ratio of magnesium over carbonate. With increasing temperature and at alkaline pH, brucite solubility further reduced the magnesium concentration to levels below 1 mmol kg-1, thus limiting availability of Mg2+(aq) for magnesite precipitation.

  5. Deposition of calcium carbonate films by a polymer-induced liquid-precursor (PILP) process

    Science.gov (United States)

    Gower, Laurie B.; Odom, Damian J.

    2000-03-01

    A polypeptide additive has been used to transform the solution crystallization of calcium carbonate to a solidification process of a liquid-phase mineral precursor. In situ observations reveal that polyaspartate induces liquid-liquid phase separation of droplets of a mineral precursor. The droplets deposit on the substrate and coalesce to form a coating, which then solidifies into calcitic tablets and films. Transition bars form during the amorphous to crystalline transition, leading to sectorization of calcite tablets, and the defect textures and crystal morphologies are atypical of solution grown crystals. The formation of nonequilibrium crystal morphologies using an acidic polypeptide may have implications in the field of biomineralization, and the environmentally friendly aspects of this polymer-induced liquid-precursor (PILP) process may offer new techniques for aqueous-based processing of ceramic films, coatings, and particulates.

  6. Study On Adsorption of Bromate From Aqueous Solution On Modified Activated Carbon

    Science.gov (United States)

    Liu, Tong-mian; Cui, Fu-yi; Zhao, Zhi-wei; Liu, Dong-mei; Zhu, Qi; Wang, Huan

    2010-11-01

    A coal-based activated carbon was treated chemically with nitric acid, sodium hydroxide and ammonia for its surface modification, and its adsorption capacity was investigated with bromate. Several techniques were used to characterize the physicochemical properties of these materials including BET, XPS, pHpzc and Boehm titration. The results indicated that the specific surface area of the activated carbon decreased after oxidation with nitric acid. But the amount of surface acidic oxygen-containing functional groups of the oxidized sample increased compared to the raw carbon and the points of zero charge (pHpzc) decreased. The specific surface area of the activated carbon also decreased after sodium hydroxide treatment and the points of zero charge increased. The changes of surface chemical properties after the ammonia treatment was opposite to the oxidized sample. As a result, the pHpzc of the carbon was increased to near pH9.3, the amount of surface basic groups was increased. Furthermore, the data of bromate adsorption on all the samples were fitted to the Langmuir isotherm model well which indicates monolayer adsorption. In addition, the adsorption capacity of ammonia treatment sample was the highest and its saturated adsorption capacity reached 1.55 mg/g. A strong correlation was found between basic groups and adsorption capacity of bromate. Enhancement of basic groups was favorable for bromate removal.

  7. Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres

    Science.gov (United States)

    de Sanctis, M. C.; Raponi, A.; Ammannito, E.; Ciarniello, M.; Toplis, M. J.; McSween, H. Y.; Castillo-Rogez, J. C.; Ehlmann, B. L.; Carrozzo, F. G.; Marchi, S.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; McFadden, L. A.; Pieters, C. M.; Jaumann, R.; Schenk, P.; Mugnuolo, R.; Raymond, C. A.; Russell, C. T.

    2016-08-01

    The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

  8. Processing and Characterization of Carbon Nanotube Composites

    Science.gov (United States)

    Can, Roberto J.; Grimsley, Brian W.; Czabaj, Michael W.; Siochi, Emilie J.; Hull, Brandon

    2014-01-01

    Recent advances in the synthesis of large-scale quantities of carbon nanotubes (CNT) have provided the opportunity to study the mechanical properties of polymer matrix composites using these novel materials as reinforcement. Nanocomp Technologies, Inc. currently supplies large sheets with dimensions up to 122 cm x 244 cm containing both single-wall and few-wall CNTs. The tubes are approximately 1 mm in length with diameters ranging from 8 to 12 nm. In the present study being conducted at NASA Langley Research Center (LaRC), single and multiple layers of CNT sheets were infused or coated with various polymer solutions that included commercial toughened-epoxies and bismaleimides, as well as a LaRC developed polyimide. The resulting CNT composites were tested in tension using a modified version of ASTM D882-12 to determine their strength and modulus values. The effects of solvent treatment and mechanical elongation/alignment of the CNT sheets on the tensile performance of the composite were determined. Thin composites (around 50 wt% CNT) fabricated from acetone condensed and elongated CNT sheets with either a BMI or polyimide resin solution exhibited specific tensile moduli approaching that of toughened epoxy/ IM7 carbon fiber unidirectional composites.

  9. Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Amin, Nevine Kamal, E-mail: nkamalamin@yahoo.com [Chemical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria (Egypt)

    2009-06-15

    The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (R{sup 2} > 0.99) and intra-particle diffusion as one of the rate determining steps. Langmuir, Freundlich, Temkin, Dubinin-RadushKevich (D-R) and Harkins-Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, various thermodynamic parameters, such as standard Gibbs free energy ({Delta}G{sup o}), standard enthalpy ({Delta}H{sup o}), standard entropy ({Delta}S{sup o}), and the activation energy (E{sub a}) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate.

  10. Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics

    International Nuclear Information System (INIS)

    The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (R2 > 0.99) and intra-particle diffusion as one of the rate determining steps. Langmuir, Freundlich, Temkin, Dubinin-RadushKevich (D-R) and Harkins-Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔGo), standard enthalpy (ΔHo), standard entropy (ΔSo), and the activation energy (Ea) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate.

  11. BATCH AND FIXED BED ADSORPTION STUDIES OF LEAD (II CATIONS FROM AQUEOUS SOLUTIONS ONTO GRANULAR ACTIVATED CARBON DERIVED FROM MANGOSTANA GARCINIA SHELL

    Directory of Open Access Journals (Sweden)

    Zaira Zaman Chowdhury,

    2012-05-01

    Full Text Available The feasibility of granular activated carbon (GAC derived from Mangostene (Mangostana garcinia fruit shell to remove lead, Pb2+ cations was investigated in batch and fixed bed sorption systems. Batch experiments were carried out to study equilibrium isotherms, kinetics, and thermodynamics by using an initial lead (Pb2+ ions concentration of 50 to 100 mg/L at pH 5.5. Equilibrium data were fitted using Langmuir, Freundlich, and Temkin linear equation models at temperatures 30°C, 50°C, and 70°C. Langmuir maximum monolayer sorption capacity was 25.00 mg/g at 30°C. The experimental data were best represented by pseudo-second-order and Elovich models. The sorption process was found to be feasible, endothermic, and spontaneous. In column experiments, the effects of initial cation concentration (50 mg/L, 70 mg/L, and 100 mg/L, bed height (4.5 cm and 3 cm, and flow rate (1 mL/min and 3 mL/min on the breakthrough characteristics were evaluated. Breakthrough curves were further analyzed by using Thomas and Yoon Nelson models to study column dynamics. The column was regenerated and reused consecutively for four cycles. The result demonstrated that the prepared activated carbon was suitable for removal of Pb2+ from synthetic aqueous solution using batch, as well as fixed bed sorption systems.

  12. Sizing and characterization of carbon fibers with aqueous water-dispersible polymeric interphases

    OpenAIRE

    Broyles, Norman S.

    1996-01-01

    Composite durability can be influenced by varying the properties of the fiber/matrix interphase region. One method to modifY the properties of this interphase is through the application of a sizing to the carbon fiber. Recent work at Virginia Tech has shown that polymer-modified interphases can lead to increases by as much as two orders of magnitude in notched fatigue lifetime. In the present work, an apparatus was constructed to uniformly coat carbon fiber tow with water-solub...

  13. Single-step colloidal processing of stable aqueous dispersions of ferroelectric nanoparticles for biomedical imaging

    International Nuclear Information System (INIS)

    The biomedical applications of ferroelectric nanoparticles rely on the production of stable aqueous colloids. We report an implementation of the high energy ball milling method to produce and disperse ultrafine BaTiO3 nanoparticles in an aqueous media in a single step. This technique is low-cost, environmentally friendly and has the capability to control nanoparticle size and functionality with milling parameters. As a result, ultrafine nanoparticles with sizes as small as 6 nm can be produced. These nanoparticles maintain ferroelectricity and can be used as second harmonic generating nanoprobes for biomedical imaging. This technique can be generalized to produce aqueous nanoparticle colloids of other imaging materials. (paper)

  14. Fabrication of Polymer Solar Cells Using Aqueous Processing for All Layers Including the Metal Back Electrode

    DEFF Research Database (Denmark)

    Søndergaard, Roar; Helgesen, Martin; Jørgensen, Mikkel;

    2011-01-01

    The challenges of printing all layers in polymer solar cells from aqueous solution are met by design of inks for the electron-, hole-, active-, and metallic back electrode-layers. The conversion of each layer to an insoluble state after printing enables multilayer formation from the same solvent ...... (water). The photograph here was taken just before screen printing of the aqueous silver ink.......The challenges of printing all layers in polymer solar cells from aqueous solution are met by design of inks for the electron-, hole-, active-, and metallic back electrode-layers. The conversion of each layer to an insoluble state after printing enables multilayer formation from the same solvent...

  15. Piperazine/N-methylpiperazine/N,N’-dimethylpiperazine as an Aqueous Solvent for Carbon Dioxide Capture

    Directory of Open Access Journals (Sweden)

    Freeman Stephanie A.

    2014-09-01

    Full Text Available A blend of piperazine (PZ, N-methylpiperazine (MPZ and N,N’-dimethylpiperazine (DMPZ is described as a novel CO2 capture solvent for aqueous absorption-stripping. This blend provides improved solid solubility and heat of absorption compared to concentrated PZ. No insolubility was observed for regions of high CO2 loading, unlike PZ solvents. The blend performed like concentrated PZ in terms of CO2 capacity and CO2 absorption rate, both of which were more than double that of a traditional 7 molal (30 wt% MonoEthanolAmine (MEA. Thermal equilibrium was established between the three constituent amines that increases the thermal stability compared to traditional blended solvents. The primary drawback of this novel solvent system is enhanced amine volatility at absorber conditions compared with both concentrated PZ and MEA.

  16. Piperazine/N-methylpiperazine/N,N'-dimethylpiperazine as an Aqueous Solvent for Carbon Dioxide Capture

    International Nuclear Information System (INIS)

    A blend of piperazine (PZ), N-methylpiperazine (MPZ) and N,N'-dimethylpiperazine (DMPZ) is described as a novel CO2 capture solvent for aqueous absorption-stripping. This blend provides improved solid solubility and heat of absorption compared to concentrated PZ. No insolubility was observed for regions of high CO2 loading, unlike PZ solvents. The blend performed like concentrated PZ in terms of CO2 capacity and CO2 absorption rate, both of which were more than double that of a traditional 7 molal (30 wt%) Monoethanolamine (MEA). Thermal equilibrium was established between the three constituent amines that increases the thermal stability compared to traditional blended solvents. The primary drawback of this novel solvent system is enhanced amine volatility at absorber conditions compared with both concentrated PZ and MEA. (authors)

  17. Controlled synthesis of calcium carbonate in a mixed aqueous solution of PSMA and CTAB

    International Nuclear Information System (INIS)

    A mixed system of poly (styrene-alt-maleic acid) (PSMA) and cetyltrimethylammonium bromide (CTAB) was used as a very effective crystal growth modifier to direct the controlled synthesis of CaCO3 crystals with various morphologies and polymorphs. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. It was found that the concentrations and relative ratios of PSMA and CTAB in the mixed aqueous solution were turned out to be important parameters for the morphology and polymorph of CaCO3 crystals. Various morphologies of CaCO3 crystals, such as hollow microsphere, peanut and so on, were produced depending on the concentrations and relative ratios of PSMA and CTAB. Moreover, the formation mechanisms of CaCO3 crystals with different morphologies were discussed

  18. Visualization of freezing process in situ upon cooling and warming of aqueous solutions.

    Science.gov (United States)

    Bogdan, Anatoli; Molina, Mario J; Tenhu, Heikki; Bertel, Erminald; Bogdan, Natalia; Loerting, Thomas

    2014-01-01

    The freezing of aqueous solutions and reciprocal distribution of ice and a freeze-concentrated solution (FCS) are poorly understood in spite of their importance in fields ranging from biotechnology and life sciences to geophysics and climate change. Using an optical cryo-microscope and differential scanning calorimetry, we demonstrate that upon cooling of citric acid and sucrose solutions a fast freezing process results in a continuous ice framework (IF) and two freeze-concentrated solution regions of different concentrations, FCS1 and FCS2. The FCS1 is maximally freeze-concentrated and interweaves with IF. The less concentrated FCS2 envelops the entire IF/FCS1. We find that upon further cooling, the FCS1 transforms to glass, whereas the slow freezing of FCS2 continues until it is terminated by a FCS2-glass transition. We observe the resumed slow freezing of FCS2 upon subsequent warming. The net thermal effect of the resumed freezing and a reverse glass-FCS1 transition produces the Ttr2-transition which before has only been observed upon warming of frozen hydrocarbon solutions and which nature has remained misunderstood for decades. PMID:25491562

  19. Infrared Thermochromic Properties of VO2 Thin Films Prepared through Aqueous Sol-gel Process

    Institute of Scientific and Technical Information of China (English)

    LIU Dongqing; CHENG Haifeng; ZHENG Wenwei; ZHANG Chaoyang

    2012-01-01

    The stoichiometric vanadium(Ⅳ) oxide thin films were obtained by controlling the temperature,time and pressure of annealing.The thermochromic phase transition and the IR thermochromic property of 400 nm and 900 nm VO2 thin films in the 7.5 μm-14 μm region were discussed.The derived VO2 thin film samples were characterized by Raman,XRD,XPS,AFM,SEM,and DSC.The resistance and infrared emissivity of VO2 thin films under different temperature were measured,and the thermal images of films were obtained using infrared imager.The results show that the VO2 thin film annealed at 550 ℃ for 10 hours through aqueous sol-gel process is pure and uniform.The 900 nm VO2 thin film exhibits better IR thermochromic property than the 400 nm VO2 thin film.The resistance of 900 nm VO2 film can change by 4orders of magnitude and the emissivity can change by 0.6 during the phase transition,suggesting the outstanding IR thermochromic property.The derived VO2 thin film can control its infrared radiation intensity and lower its apparent temperature actively when the real temperature increases,which may be applied in the field of energy saving,thermal control and camouflage.

  20. Assessment of suitability of vine shoots for hemicellulosic oligosaccharides production through aqueous processing.

    Science.gov (United States)

    Dávila, Izaskun; Gordobil, Oihana; Labidi, Jalel; Gullón, Patricia

    2016-07-01

    Vine shoots were subjected to non-isothermal aqueous processing. A range of severities (S0) from 3.20 to 4.65 was assayed and their effects in terms of solubilization, composition, molar mass distribution, structural characterization and thermal stability of the liquors were studied using HPLC, HPSEC, TGA and FTIR. The spent solids were characterized by HPLC and FTIR. When autohydrolysis was carried out at S0=4.01, the substrate solubilization achieved a 38.7% of the raw material and 83.1% of the initial xylan was converted into xylooligosaccharides (XOS). The amount of TOS (total oligosaccharides) in the hydrolysates was 28.4g/L while the other non volatile compounds (ONVC) were 0.08g/g NVC. The spent solid from the treatment at S0=4.01 was composed about 90% of cellulose and lignin. Therefore, it can be concluded that autohydrolysis is a suitable pretreatment of vine shoots such as a first stage of a biomass refinery. PMID:27054881

  1. Effects of ultrasonic processing on degradation of salvianolic acid B in aqueous solution.

    Science.gov (United States)

    Guo, Y X; Zhang, L; Lu, L; Liu, E H; Shi, C Z

    2016-09-10

    To evaluate the stability of salvianolic acid B (Sal B) under ultrasound-assisted extraction in the pharmaceutical industry, degradation of Sal B under ultrasonic irradiation was investigated as the function of buffer concentration, pH, and temperature. With regard to Sal-B concentration, a first-order degradation process was determined, with 10% change in assay from its initial concentration as t90=4.81h, under maximum stability acidic conditions (pH 2.0) and at 25°C. The logkpH-pH profile described by specific acid-base catalysis and water molecules supported the experimental results. Liquid chromatography-mass spectrometry (LC-MS) analyses revealed 7 major degradation products whose structures were characterized by electrospray ionization/mass spectrometry. A primary degradation pathway involved cleavage of the ester bond and ring-opening of benzofuran in Sal B was proposed. The complete degradation pathway of Sal B was also proposed. Results showed that ultrasonic irradiation leads to degradation of Sal B in aqueous solution. PMID:27442887

  2. Pyrite oxidation by hexavalent chromium: investigation of the chemical processes by monitoring of aqueous metal species.

    Science.gov (United States)

    Demoisson, Frédéric; Mullet, Martine; Humbert, Bernard

    2005-11-15

    Pyrite, an iron sulfide, occurs in many soils and sediments, making it an important natural reductant of toxic metal pollutants. This study investigated the processes leading to aqueous Cr(VI) reduction by pyrite in a closed thermostated (25 +/- 0.1 degrees C) system and under an argon atmosphere. Synthetic pyrite suspensions were reacted with a range of Cr(VI) solutions from 0 to 7 x 10(-4) M and at pH 2-8. Metal species concentrations were continuously monitored during a period lasting approximately 20 h. Preliminary experiments carried out in acidic media without Cr(VI) have shown that some pyrite dissolution occurred. Then, metal species concentration changes with time during pyrite oxidation by Cr(VI) solutions exhibited two distinct trends depending on the complete or incomplete Cr(VI) removal. As long as chromate existed in solution, the Cr-(Ill) to Fe(lIl) ratio was found to be an effective parameter to investigate the pyrite reaction stoichiometry with Cr(VI). Experimental values close to 2 suggest that sulfur compounds with oxidation states between 0 and 2 should be formed during pyrite oxidation by Cr(VI). If Cr(VI) was completely reduced from solution, then the pyrite oxidation by Fe(lll) ions took place to generate ferrous ions. PMID:16323772

  3. Tungstate as a synergist to phosphonate-based formulation for corrosion control of carbon steel in nearly neutral aqueous environment

    Indian Academy of Sciences (India)

    B V Appa Rao; M Venkateswara Rao; S Srinivasa Rao; B Sreedhar

    2010-07-01

    Synergistic inhibition of corrosion of carbon steel in low chloride aqueous medium using tungstate as a synergist in combination with ,-(phosphonomethyl) glycine (BPMG) and zinc ions is presented. The synergistic action of tungstate has been established through the present studies. The new ternary inhibitor formulation is effective in neutral and slightly acidic as well as slightly alkaline media. Potentiodynamic polarisation studies inferred that the formulation functions as a mixed inhibitor. Impedance studies of the metal/solution interface revealed that the surface film is highly protective. Characterisation by X-ray photoelectron spectroscopy (XPS) of the surface film formed in presence of the inhibitor revealed the presence of iron, phosphorus, nitrogen, oxygen, carbon, zinc and tungsten in the surface film. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of iron oxides/hydroxides, zinc hydroxide, heteropolynuclear complex [Fe(III), Zn(II)-BPMG] and WO3. Reflection absorption FTIR spectroscopic studies also supported the presence of these compounds in the surface film. Morphological features of the metal surface studied in the absence and presence of the inhibitor by scanning electron microscopy (SEM) are also presented. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  4. Effects of solution P H on the adsorption of aromatic compounds from aqueous solutions by activated carbon

    International Nuclear Information System (INIS)

    Absorption of p-Cresol, Benzoic acid and Nitro Benzene by activated carbon from dilute aqueous solutions was carried out under controlled ph conditions at 310 k. In acidic conditions, well below the pKa of all solutes, it was observed that the adsorbate solubility and the electron density of its aromatic ring were the influencing factors on the extent of the adsorption by affecting the extent of London dispersion forces. In higher solution ph conditions, on the other hand, it was found that the electrostatic forces played a significant role on the extent of adsorption. The Effect of ph must be considered from its combined effects on the carbon surface and on the solute molecules. It was found that the uptake of the molecular forms of the aromatic solutes was dependent on the substituents of the aromatic ring. Adsorption of the solutes in higher P H values was found to be dependent on the concentration of anionic form of the solutes. All isotherms were fitted into Freundlich Isotherm Equations

  5. Effect of the rheological properties of carbon nanotube dispersions on the processing and properties of transparent conductive electrodes.

    Science.gov (United States)

    Maillaud, Laurent; Poulin, Philippe; Pasquali, Matteo; Zakri, Cécile

    2015-06-01

    Transparent conductive films are made from aqueous surfactant stabilized dispersions of carbon nanotubes using an up-scalable rod coating method. The processability of the films is governed by the amount of surfactant which is shown to alter strongly the wetting and viscosity of the ink. The increase of viscosity results from surfactant mediated attractive interactions between the carbon nanotubes. Links between the formulation, ink rheological properties, and electro-optical properties of the films are determined. The provided guidelines are generalized and used to fabricate optimized electrodes using conductive polymers and carbon nanotubes. In these electrodes, the carbon nanotubes act as highly efficient viscosifiers that allow the optimized ink to be homogeneously spread using the rod coating method. From a general point of view and in contrast to previous studies, the CNTs are optimally used in the present approach as conductive additives for viscosity enhancements of electronic inks. PMID:25961667

  6. Corrosion inhibitors for neutral aqueous media based on the products on sugar cane processing. 1.Furfural derivatives as inhibitors

    International Nuclear Information System (INIS)

    A series of carboxy-, nitrogen- and nitroderivaties of furfural - the main product of sugar cane processing (furancasboxylic acid, 5-nitrofurancarboxylic acid and its salts, furfurine, furfurylamine) was studied as inhibitors of iron and copper, corrosion in aqueous-salt media. Nitrofuroates of sodium and ammonium, which decelerate anode process, intensity cathode one and provide the stable passive state, are considered to be the most effective

  7. Optimization of the Parameters Affecting the Fenton Process for Decolorization of Reactive Red 198 (RR-198) from the Aqueous Phase

    OpenAIRE

    Mansooreh Dehghani; Mahshid Ghadami; Talat Gholami; Marzieh Ansari Shiri; Zahra Elhameyan; Mohammad Reza Javaheri; Narges Shamsedini; Samaneh Shahsavani

    2015-01-01

    Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Reactive dyes are widely used in textile industry. Advanced oxidation processes are one of the cost-effective methods for the removal of these dyes. The main aims of this study were determining the feasibility of using Fenton process in removing Reactive Red 198 (RR-198) dye from aqueous so...

  8. Novel Method for Breakthrough Removal of Azo Dye from Aqueous Environment Using Integrated Coagulation and Fenton Process

    OpenAIRE

    Sherine Awad; Usama Eldemerdash

    2014-01-01

    Fenton process has proven to be efficient in the removal of color and chemical oxygen demand (COD) from the aqueous environment. However, the environment, health, and economic constraints on the dosage of hydrogen peroxide represent a limitation towards a wide practical use of this approach. In this study, a novel approach is proposed; this includes the treatment with ferrous oxide through coagulation followed by integrated Fenton process. However, the excess ferrous and ferric ions from the ...

  9. Process for plutonium rextraction in aqueous solution from an organic solvent, especially for uranium plutonium partition

    International Nuclear Information System (INIS)

    The organic solvent containing plutonium is contacted with an aqueous solution of a uranous salt, for instance uranous nitrate, and a hydroxylamine salt, for instance the nitrate. In these conditions uranous nitrate is a reducing agent of Pu III and hydroxylamine nitrate stabilizes Pu III and U IV in the aqueous phase. Performances are similar to these of the U IV-hydrazine nitrate without interference of hydrazine nitrate degradation products

  10. Crystallization processes of hydrous metal oxides in the presence of aqueous-phase

    International Nuclear Information System (INIS)

    Evaluation of solubility-limiting solid is a central theme for predicting the rate of radionuclide release from HLW repository to the accessible environment. Such solids which control the concentration of radionuclide in subsurface water are considered to be sparingly soluble hydrous oxides. However, most of the hydrous oxides are thermodynamically unstable and alter from the amorphous form into crystal (oxyhydroxide or oxide), which, in turn, changes the solubility of radionuclide drastically. So far, such crystallization rates have been hardly clarified. This co-operative research focused on (1) the crystallization process from amorphous Fe(OH)3 to goethite, i.e., α-FeO(OH), and (2) the precipitation of Ce(III) or Ce(IV) and the chemical change in ageing. To begin with, the method to determine the crystallization fraction has been developed for the study. This method using TG(thermogravimetry)-curve quantifies the mole fraction of crystalline hydrous oxides, e.g., (Fe in goethite)/(total Fe in hydrous iron oxides precipitated). Using this method, the crystallization process of Fe(OH)3 was examined. The experimental parameters were the ageing time, pH-value, temperature, and dehydration methods. The results suggested that the aqueous phase plays an important role in changing the chemical structure into the crystal form. This tendency was observed also in the hydrous oxides of Ce(III) and Ce(IV). Further, the crystallization rate of Ce(OH)4 to CeO2 depended on the initial amount of CeO2 in ageing (although its amount of CeO2 was relatively small as compared to Ce(OH)4). These information will contribute to predicting the solubility-limiting solid in the performance assessment of HLW repository system. (author)

  11. Removal of uranium(VI) from aqueous solutions by new phosphorus-containing carbon spheres synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid

    International Nuclear Information System (INIS)

    The novel phosphorus-rich hydrothermal carbon spheres (HCSs-PO4) have been synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid. The textural and surface chemistry properties were characterized using Boehm titrations, scanning electron microscopy and Fourier transform infrared spectrometer. The content of oxygen-containing functional groups on the surface of HCSs increased from 0.053 to 1.009 mmol g-1 by phosphate group modification. The adsorption ability of HCSsPO4 has been explored for the removal of uranium from aqueous solutions. The adsorption kinetic data were best described by the pseudo-second-order equation. Adsorption process could be well defined by the Langmuir isotherm, the adsorption capacity of HCSs increased from 80.00 to 285.70 mg g-1 after phosphate group modification. And thermodynamic parameters indicated the adsorption process was feasible,endothermic and spontaneous. Selective adsorption studies showed that the HCSs-PO4 could selectively remove U(VI), and the selectivity coefficients had been improved in the presence of co-existing ions, Na(I), Ni(II), Sr(II), Mn(II), Mg(II) and Zn(II). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 12.0 g HCSs-PO4. (author)

  12. Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

    Directory of Open Access Journals (Sweden)

    S. M. Yakout

    2009-05-01

    Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

  13. Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Xiaoming, E-mail: pengxiaoming70@126.com [School of Civil Engineering, Southeast University, Nanjing 210096 (China); Hu, Xijun [Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,China (China); Fu, Dafang, E-mail: fdf@seu.edu.cn [School of Civil Engineering, Southeast University, Nanjing 210096 (China); Lam, Frank L.Y. [Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,China (China)

    2014-03-01

    Highlights: • Ordered mesoporous carbon was prepared using template. • Ordered mesoporous carbon was introduced of N-containing group by Chemical vapor deposition method. • Modified CMK-3 have better adsorption capacity and efficiency than virgin CMK-3 to removal AB1 dye. - Abstract: A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT–IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the fitter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

  14. Removal of boron from aqueous solution using magnetic carbon nanotube improved with tartaric acid

    OpenAIRE

    Zohdi, Nima; Mahdavi, Fariba; Abdullah, Luqman Chuah; Choong, Thomas SY

    2014-01-01

    Boron removal capacity of multi-walled carbon nanotubes (MWCNTs) modified with tartaric acid was investigated in this study. Modification of MWCNTs with tartaric acid was confirmed by Boehm surface chemistry method and fourier transform infra-red (FT-IR) spectroscopy. Experiments were performed to determine the adsorption isotherm and adsorption thermodynamic parameters of boron adsorption on tartaric acid modified MWCNTs (TA-MWCNTs). The effect of variables including initial pH, dosage of ad...

  15. Optimization and Modeling of Hexavalent Chromium Removal from Aqueous Solution Via Adsorption on Multiwalled Carbon Nanotubes

    OpenAIRE

    Mina Gholipour; Hassan Hashemipour Rafsanjani; Ataollah Soltani Goharrizi

    2011-01-01

    Hexavalent chromium and its derivatives are potential pollutant due to their mortal affects. Therefore, It is essential to remove these components from wastewaters before disposal. Adsorption can be effective and versatile method for removing of hexavalent chromium. In this article, removal of hexavalent chromium via adsorption on multiwalled carbon nanotubes was investigated as a function of adsorbent dosage, initial solution pH, initial Cr(VI) concentrations, contact time and temperature. T...

  16. Removal of cationic surfactant (CTAB) from aqueous solution on to activated carbon obtained from corncob.

    OpenAIRE

    S. M. Yakout; A. A. Nayl

    2009-01-01

    Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC) as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effective...

  17. The chemistry of uranium (VI), neptunium (VI), and plutonium (VI) in aqueous carbonate solutions

    International Nuclear Information System (INIS)

    The dynamic behavior of carbonate ion as a ligand that interacts with the hexavalent actinyl ions of U, Np, and Pu was examined by 13C NMR spectroscopy. The first-order rate parameter, k, that describes the exchange between bulk solution and bound carbonate decreases with increasing pH. At a pH of 10.0, and 25 degrees C, the respective values of k for the U(VI), Np(VI) complexes are 27.1 ± 0.3, 64.7 ± 3.3, and 706 ± 29. The variation of k with temperature was used to calculate the values of activation enthalpy ΔH double-dagger = 53 and 42 kJ mol-1; and activation entropy ΔS double-dagger = - 40 and - 71 J mol-1 K-1 for the uranyl and neptunyl systems, respectively. In this paper a plausible reaction scheme for the exchange reaction is considered. The influence of these slow carbonate-exchange reactions on selected electron-transfer reactions is noted

  18. Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

    Science.gov (United States)

    Lamb, James L.; Dickie, Matthew R.; Kowalczyk, Robert S.; Liao, Anna; Bronikowski, Michael J.

    2012-01-01

    Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles.

  19. Calcification-carbonation method for red mud processing.

    Science.gov (United States)

    Li, Ruibing; Zhang, Tingan; Liu, Yan; Lv, Guozhi; Xie, Liqun

    2016-10-01

    Red mud, the Bayer process residue, is generated from alumina industry and causes environmental problem. In this paper, a novel calcification-carbonation method that utilized a large amount of the Bayer process residue is proposed. Using this method, the red mud was calcified with lime to transform the silicon phase into hydrogarnet, and the alkali in red mud was recovered. Then, the resulting hydrogarnet was decomposed by CO2 carbonation, affording calcium silicate, calcium carbonate, and aluminum hydroxide. Alumina was recovered using an alkaline solution at a low temperature. The effects of the new process were analyzed by thermodynamics analysis and experiments. The extraction efficiency of the alumina and soda obtained from the red mud reached 49.4% and 96.8%, respectively. The new red mud with <0.3% alkali can be used in cement production. Using a combination of this method and cement production, the Bayer process red mud can be completely utilized. PMID:27214002

  20. Removal of uranium(VI) from aqueous solutions by carboxyl-rich hydrothermal carbon spheres through low-temperature heat treatment in air

    International Nuclear Information System (INIS)

    Carboxyl-rich hydrothermal carbon spheres were prepared by simply heating pristine hydrothermal carbon spheres (HCSs) at lower temperature in air, and the textural properties were characterized using Boehm titrations, scanning electron microscopy, Fourier transform infrared spectrometer (FT-IR) and elemental-analysis. The result of Boehm titrations indicated that the content of carboxyl groups on HCSs increased significantly from 0.53 to 3.81 mmol/g after heat-treatment at 300 deg C, which was also confirmed by FT-IR and EA qualitatively. The ability of heat-treated HCSs has been explored for the removal and recovery of uranium from aqueous solutions, and the influences of different experimental parameters, such as heat-treatment temperature, contact time and ionic strength, on adsorption were investigated. The U(VI) sorption capacity of HCSs increased from 55.0 to 179.95 mg/g after heat-treatment at 300 deg C for 5 h. Selective adsorption studies showed that the heat-treated HCSs could selectively remove U(VI), and the selectivity coefficients were improved after heat-treatment in the presence of co-existing ions, Na(I), Ni(II), Sr(II), Mn(II), Mg(II) and Zn(II). The adsorbent HCSs could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.0 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 5.0 g heat-treated HCSs. In addition, a reaction mechanism for newly generating carboxyl groups on pristine HCSs surface during heat-treatment process and uranyl ion interaction with carboxyl-rich hydrothermal carbon spheres were also supposed. (author)

  1. Carbon redistribution by erosion processes in an intensively disturbed catchment

    Science.gov (United States)

    Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

    2016-04-01

    reforestation works. However the organic carbon in deposited sediments comes not only from surface erosion processes, but also from deeper soil or sediment layers mobilized by concentrated erosion processes. Sediment richer in organic carbon comes from the soil surface of vegetated (reforested) areas close and well connected to the channels. Subcatchments dominated by laminar erosion processes showed two times higher TOC/total erosion ratio than subcatchments dominated by concentrated flow erosion processes. Lithology, soils and geomorphology exert a more important control on organic carbon redistribution than land use and vegetation cover in this geomorphologically very active catchment.

  2. Efficient and Stable Carbon-coated Nickel Foam Cathodes for the Electro-Fenton Process

    International Nuclear Information System (INIS)

    Highlights: • Carbon-coated nickel foam (C@NF) was prepared by cycle coating carbon process. • Ni leaching can be effectively controlled at C@NF4 (4 cycle coating times) cathode. • C@NF4 exhibits excellent electro-Fenton performance with desirable stability. • C@NF4 exhibits low energy consumption for DMP degradation. - Abstract: Carbon-coated nickel foam (C@NF) electrodes are prepared via a simple and effective method, hydrothermal-carbonization cycle coating process, characterized by scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and employed as the electro-Fenton (E-Fenton) cathode for degrading dimethyl phthalate (DMP) in aqueous solution. For the sake of comparison, nickel foam (NF) electrode and the conventional E-Fenton cathode (graphite gas diffusion electrode (GDE)) are also tested and compared. Experimental results indicate that nickel leaching can be effectively controlled at C@NF4 cathode (4 times cycle coating process), having great significance for promoting the application of NF in E-Fenton system. Moreover, C@NF4 cathode still presents excellent and effective performance on DMP degradation. DMP can be completely degraded within 2 h at −0.5 V and the total organic carbon (TOC) removal reaches as high as 82.1 %, which is almost 3 times as high as that at graphite GDE. Futhermore, the current efficiency for H2O2 generation at C@NF4 is enhanced by 12 times compared to that at NF, and consequently the energy consumption during DMP degradation at C@NF4 is obvious lower than that at both NF cathode and graphite GDE. From the obtained results it can be deduced that C@NF4 is promising to be an attractive alternative E-Fenton cathode for removing organic pollutants in wastewater

  3. Graphitizing Process of the Self—Baking Carbon Block

    Institute of Scientific and Technical Information of China (English)

    HUXiaojun; XUEXiangxin; 等

    1998-01-01

    The different specimens of the Self-Baking Carbon Block are obtained by charging the baking temperature and time.The graphitizing degree G of the specimen is determined by the quantitiative X-ray diffraction.The relationships between G and temperature are expressed.The results show that the graphitizing process from amorphous carbon to graphite is apparent quasi-one-order and should be conducted above a critical temperature.1200K The transition rate increases with tenperature.

  4. Radiation processing for PTFE composite reinforced with carbon fiber

    International Nuclear Information System (INIS)

    The present work is an attempt to evaluate the performance of crosslinked PTFE as a polymer matrix for carbon fiber-reinforced composite materials. The carbon fiber-reinforced PTFE pre-composite, which is laminated with PTFE fine powder, is crosslinked by electron beam irradiation. Mechanical and frictional properties of the crosslinked PTFE composite obtained are higher than those of PTFE resin. The crosslinked PTFE composite with high mechanical and radiation resistant performance is obtained by radiation crosslinking process

  5. Automated determination of the stable carbon isotopic composition (δ13C) of total dissolved inorganic carbon (DIC) and total nonpurgeable dissolved organic carbon (DOC) in aqueous samples: RSIL lab codes 1851 and 1852

    Science.gov (United States)

    Révész, Kinga M.; Doctor, Daniel H.

    2014-01-01

    The purposes of the Reston Stable Isotope Laboratory (RSIL) lab codes 1851 and 1852 are to determine the total carbon mass and the ratio of the stable isotopes of carbon (δ13C) for total dissolved inorganic carbon (DIC, lab code 1851) and total nonpurgeable dissolved organic carbon (DOC, lab code 1852) in aqueous samples. The analysis procedure is automated according to a method that utilizes a total carbon analyzer as a peripheral sample preparation device for analysis of carbon dioxide (CO2) gas by a continuous-flow isotope ratio mass spectrometer (CF-IRMS). The carbon analyzer produces CO2 and determines the carbon mass in parts per million (ppm) of DIC and DOC in each sample separately, and the CF-IRMS determines the carbon isotope ratio of the produced CO2. This configuration provides a fully automated analysis of total carbon mass and δ13C with no operator intervention, additional sample preparation, or other manual analysis. To determine the DIC, the carbon analyzer transfers a specified sample volume to a heated (70 °C) reaction vessel with a preprogrammed volume of 10% phosphoric acid (H3PO4), which allows the carbonate and bicarbonate species in the sample to dissociate to CO2. The CO2 from the reacted sample is subsequently purged with a flow of helium gas that sweeps the CO2 through an infrared CO2 detector and quantifies the CO2. The CO2 is then carried through a high-temperature (650 °C) scrubber reactor, a series of water traps, and ultimately to the inlet of the mass spectrometer. For the analysis of total dissolved organic carbon, the carbon analyzer performs a second step on the sample in the heated reaction vessel during which a preprogrammed volume of sodium persulfate (Na2S2O8) is added, and the hydroxyl radicals oxidize the organics to CO2. Samples containing 2 ppm to 30,000 ppm of carbon are analyzed. The precision of the carbon isotope analysis is within 0.3 per mill for DIC, and within 0.5 per mill for DOC.

  6. Identification of Green Rust Compounds in the Aqueous Corrosion Processes of Steels; the Case of Microbially Induced Corrosion and Use of 78 K CEMS

    Science.gov (United States)

    Génin, J.-M. R.; Refait, Ph.; Olowe, A. A.; Abdelmoula, M.; Fall, I.; Drissi, S. H.

    1998-12-01

    Fe(II)-Fe(III) hydroxy-sulphate Green Rust 2, GR2(SO4 -), is obtained by microbially induced corrosion of steel. Transmission Mössbauer spectroscopy (TMS) was used to characterise the corrosion products of steel sheet piles under the biofilm at low sea-water level in a harbour. To understand the process, iron coupons maintained in aqueous solutions of 4 M NaCl and 0.1 M NaHCO3 of pH 7.4 were studied by X ray diffraction and conversion electron Mössbauer spectroscopy (CEMS) at 78 K. The Fe(II)-Fe(III) hydroxy-carbonate, GR1(CO3 -), covers the surface, as predicted by the Eh-pH diagram.

  7. Spectroscopic and electrochemical studies of selected lanthanides and actinides in concentrated aqueous carbonate and carbonate-hydroxide solutions and in molten dimethyl sulfone

    International Nuclear Information System (INIS)

    Electrochemical and spectroscopic studies of neptunium, plutonium, americium, californium, and terbium in concentrated aqueous carbonate and carbonate-hydroxide solutions have been carried out. Changes in the absorption spectra of Np(VII), Np(V), Pu(VI), Pu(V), Am(VI), and Am(V) in concentrated Na2CO3 solution and in the formal potentials of the Np(VI)/Np(V) and Pu(VI)/Pu(V) couples as a function of pH were observed. Heptavalent neptunium in concentrated Na2CO3 solution could only be producted at pH values close to or greater than 14. Plutonium(VII) in 2 M Na2CO3 solution could only be produced at hydroxide ion concentrations in excess of about 2.5 M. The complexation of Np(VII) and Pu(VII) in Na2CO3-NaOH solution seems to be mainly by hydroxide ions. Neptunium(IV) and plutonium(IV) are insoluble in Na2CO3 solution above ca. pH 11-12. Neptunium(III) in carbonate solution is rapidly oxidized by water to Np(IV). Plutonium(III) is insoluble in Na2CO3 solution. In K2CO3 solution Pu(III) is stable to oxidation by water but is very sensitive to air oxidation. The redox properties of Cf(III) in Na2CO3 and K2CO3 solutions at pH values from 8 to 14 were investigated. The oxidation of terbium(III) in K2CO3-KOH solution was studied. Spectroscopic and electrochemical studies of cerium, samarium, europium, ytterbium, uranium, neptunium, plutonium, and americium in molten dimethyl sulfone (DMSO2) at 400 K were performed. Differences in the DMSO2 solution absorption spectra of trivalent Sm, Eu, and Yb and divalent Eu compared with those in aqueous solution were observed. Complexation effects on the spectra of Ce(III), Ce(IV), U(VI), Np(VI), Pu(VI), and Am(VI) are more noticeable in poorly coordinating DMSO2 than they are in water. 123 references, 54 figures, 11 tables

  8. Process for derivatizing carbon nanotubes with diazonium species

    Science.gov (United States)

    Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

    2007-01-01

    The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

  9. Adsorption of Phenol from Aqueous Solutions by Carbon Nanomaterials of One and Two Dimensions: Kinetic and Equilibrium Studies

    Directory of Open Access Journals (Sweden)

    M. de la Luz-Asunción

    2015-01-01

    Full Text Available Carbon nanomaterials have a great potential in environmental studies; they are considered as superior adsorbents of pollutants due to their physical and chemical properties. Functionalization and dimension play an important role in many functions of these nanomaterials including adsorption. In this research, adsorption process was achieved with one-dimension nanomaterials: single walled and multiwalled carbon nanotubes were used as received and after oxidation treatment also two-dimensional nanomaterials were used: graphene oxide and reduced graphene oxide. Carbon nanotubes were modified by hydrogen peroxide under microwave irradiation. The reduction of graphene oxide was achieved by using ascorbic acid. R2 values obtained with the pseudo-second-order model are higher than 0.99. The results demonstrate that Freundlich isotherm provides the best fit for the equilibrium data (R2>0.94. RL values are between 0 and 1; this represents favorable adsorption between carbon nanomaterials and phenol. The adsorption process occurs by π-π interactions and hydrogen bonding and not by electrostatic interactions. The results indicate that the adsorption of phenol on carbon nanomaterials depends on the adsorbents’ surface area, and it is negatively influenced by the presence of oxygenated groups.

  10. Carbon tetrachloride induced kidney and lung tissue damages and antioxidant activities of the aqueous rhizome extract of Podophyllum hexandrum

    Directory of Open Access Journals (Sweden)

    Zargar Bilal

    2011-02-01

    Full Text Available Abstract Background The present study was conducted to evaluate the in vitro and in vivo antioxidant properties of aqueous extract of Podophyllum hexandrum. The antioxidant potential of the plant extract under in vitro situations was evaluated by using two separate methods, inhibition of superoxide radical and hydrogen peroxide radical. Carbon tetrachloride (CCl4 is a well known toxicant and exposure to this chemical is known to induce oxidative stress and causes tissue damage by the formation of free radicals. Methods 36 albino rats were divided into six groups of 6 animals each, all animals were allowed food and water ad libitum. Group I (control was given olive oil, while the rest groups were injected intraperitoneally with a single dose of CCl4 (1 ml/kg as a 50% (v/v solution in olive oil. Group II received CCl4 only. Group III animals received vitamin E at a concentration of 50 mg/kg body weight and animals of groups IV, V and VI were given extract of Podophyllum hexandrum at concentration dose of 20, 30 and 50 mg/kg body weight. Antioxidant status in both kidney and lung tissues were estimated by determining the activities of antioxidative enzymes, glutathione reductase (GR, glutathione peroxidase (GPX, glutathione-S-transferase (GST and superoxide dismutase (SOD; as well as by determining the levels of reduced glutathione (GSH and thiobarbituric acid reactive substances (TBARS. In addition, superoxide and hydrogen peroxide radical scavenging activity of the extract was also determined. Results Results showed that the extract possessed strong superoxide and hydrogen peroxide radical scavenging activity comparable to that of known antioxidant butylated hydroxy toluene (BHT. Our results also showed that CCl4 caused a marked increase in TBARS levels whereas GSH, SOD, GR, GPX and GST levels were decreased in kidney and lung tissue homogenates of CCl4 treated rats. Aqueous extract of Podophyllum hexandrum successfully prevented the alterations

  11. Kinetics and thermodynamics of adsorption of ionizable aromatic compounds from aqueous solutions by as-prepared and oxidized multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    The adsorption of 1-naphthylamine, 1-naphthol and phenol on as-prepared and oxidized multiwalled carbon nanotubes (MWCNTs) has been investigated. The results illustrated that both as-prepared and oxidized MWCNTs showed high adsorption capacity for the three ionizable aromatic compounds (IACs) studied. Oxidation of MWCNTs increased the surface area and the pore volume, and introduced oxygen-containing functional groups to the surfaces of MWCNTs, which depressed the adsorption of IACs on MWCNTs. Both Langmuir and Freundlich models described the adsorption isotherms very well and the adsorption thermodynamic parameters (ΔGo, ΔHo and ΔSo) were measured. The adsorption for 1-naphthylamine, 1-naphthol and phenol is general spontaneous and thermodynamically favorable. The adsorption of phenol is an exothermic process, whereas the adsorption of 1-naphthylamine and 1-naphthol is an endothermic process. Results of this work are of great significance for the environmental application of MWCNTs for the removal of IACs from large volume of aqueous solutions.

  12. Modeling of carbon dioxide absorption by aqueous ammonia solutions using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J. M.; Stenby, Erling Halfdan;

    2010-01-01

    An upgraded version of the Extended UNIQUAC thermodynamic model for the carbon dioxide-ammonia-water system has been developed, based on the original version proposed by Thomsen and Rasmussen. The original model was valid in the temperature range 0-110°C, the pressure range 0-10 MPa and the...... ranges, enthalpy change from partial evaporation measurements, speciation data, heat capacity, enthalpy of solution and enthalpy of dilution data have been used to refit 43 model parameters and standard state properties. Henry’s law constant correlations have been used for extrapolating standard state...

  13. Theoretical modelling of carbon deposition processes

    International Nuclear Information System (INIS)

    Work based on capsule experiments in the BNL Gamma Facility, aimed at elucidating the chemistry involved in the formation of carbonaceous deposit on CAGR fuel pin surfaces is described. Using a data-base derived from capsule experiments together with literature values for the kinetics of the fundamental reactions, a chemical model of the gas-phase processes has been developed. This model successfully reproduces the capsule results, whilst preliminary application to the WAGR coolant circuit indicates the likely concentration profiles of various radical species within the fuel channels. (author)

  14. A COMPOSITE HOLLOW FIBER MEMBRANE-BASED PERVAPORATION PROCESS FOR SEPARATION OF VOCS FROM AQUEOUS SURFACTANT SOLUTIONS. (R825511C027)

    Science.gov (United States)

    The separation and recovery of VOCs from surfactant-containing aqueous solutions by a composite hollow fiber membrane-based pervaporation process has been studied. The process employed hydrophobic microporous polypropylene hollow fibers having a thin plasma polymerized silicon...

  15. Aggregation and self-assembly of amphiphilic block copolymers in aqueous dispersions of carbon nanotubes.

    Science.gov (United States)

    Shvartzman-Cohen, Rina; Florent, Marc; Goldfarb, Daniella; Szleifer, Igal; Yerushalmi-Rozen, Rachel

    2008-05-01

    The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for characterization of the thermal behavior of the combined polymers-nanostructures system, and spin-probe electron paramagnetic resonance (EPR) was employed for probing the local dynamic and polarity of the polymer chains in the presence of nanostructures. It was found that SWNT and MWNT modify the temperature, enthalpy, and dynamic behavior of polymer SA. In particular, SWNT were found to increase the cooperativity of aggregating chains and dominate aggregate dynamics. MWNT reduced the cooperativity, while colloidal carbon black additives, studied for comparison, did not show similar effects. The experimental observations are consistent with the suggestion that dimensional matching between the characteristic radius of the solvated polymer chains and the dimensions of additives dominate polymer SA in the hybrid system. PMID:18355098

  16. Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon

    Science.gov (United States)

    Peng, Xiaoming; Hu, Xijun; Fu, Dafang; Lam, Frank L. Y.

    2014-03-01

    A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the fitter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

  17. Spatial frequency heterodyne imaging of aqueous phase transitions inside multi-walled carbon nanotubes.

    Science.gov (United States)

    Schunk, F M; Rand, D; Rose-Petruck, C

    2015-12-14

    The evaporation and condensation of water on multi-walled carbon nanotube (MWCNT) surfaces was studied as a function of temperature and time using X-ray spatial frequency heterodyne imaging (SFHI). SFHI is an imaging modality that produces an absorption and scatter image in a single exposure, and has increased sensitivity to variations in electron density relative to more common place X-ray imaging techniques. Differing features exhibited in the temporal scatter intensity profiles recorded during evaporation and condensation revealed the existence of an absorption-desorption hysteresis. Effects on the aforementioned phenomena due to chemical functionalization of the carbon nanotube surfaces were also monitored. The increased interaction potential between the functionalized MWCNT walls and water molecules altered the evaporation event time scale and increased the temperature at which condensation could take place. Theoretical calculations were used to correlate the shape of the observed scatter profiles during condensation to changes in the MWCNT cross section geometry and configuration of the contained water volume. Changes in evaporation time scales with temperature coincided with the boiling point for confined water predicted by the Kelvin equation, indicating that a thermodynamic description of mesoscopic confined water is permissible in some instances. PMID:26549826

  18. Green synthesis of biocompatible carbon dots using aqueous extract of Trapa bispinosa peel

    International Nuclear Information System (INIS)

    We are reporting highly economical plant based method for the production of luminescent water soluble carbon dots (C-dot) using Indian water plant Trapa bispinosa peel extract without adding any external oxidizing agent at 90 °C. C-dots ranging from 5 to 10 nm were found in the solution with a prominent green fluorescence under UV-light (λex = 365 nm). UV–vis spectra recorded at different time intervals (30–120 min) displayed signature absorption of C-dots between 400 and 600 nm. Fluorescence spectra of the dispersion after 120 min of synthesis exhibited characteristic emission peaks of C-dots when excited at 350, 400, 450 and 500 nm. C-dots were further analyzed using X-ray diffraction (XRD), Raman Spectroscopy and Thermo-Gravimetric Analysis (TGA). Structure of the C-dots was found to be turbostratic when studied using XRD. C-dots synthesized by our method were found to be exceptionally biocompatible against MDCK cells. Highlights: • Novel report on biosynthesis of water soluble carbon dots using plant source • Prominent green fluorescence under UV light • Highly biocompatible nanoparticles against MDCK cells • Excellent imaging properties under fluorescent light

  19. Sintering process study of boron carbide with carbon addition

    International Nuclear Information System (INIS)

    This work studies the pressureless sintering process of boron carbide with carbon addition, in order to obtain absorber pellets to the nuclear reactors PWR. Sintering's tests were made with addition of 1 to 10% weight of carbon in several temperature, to determine the influence of these parameters in sintering process. The original material was leached in sulfochromic solution to remove the free carbon present. Sample sintering microstructure were analyzed by scanning electronic microscopic. Different stages of sintering were observed and we tried to identify the process that avoid the densification. The leached material with sulfochromic solution, as coarse material, showed limited densification during the sintering, showing a pores structure, coarsening, with grain/particle domains separated by interconnected pores. The several stages evolution of densification process denotes that the surface to surface transport leads the structure coarsened. The limited densification coincides with the coarsened microstructure and it can be explained in terms of kinetic and thermodynamic barriers. Carbon additions and powder with smaller particles got easier the densification, that allowed to obtain pellets with densities 97% TD at 22000 C. It's believed that carbon inhibited the surface to surface transport and coarsening, because it would eliminate or control the oxygen activity. (author). 97 refs., 60 figs., 7 tabs

  20. Process for recovering organic values from aqueous solutions containing both organic values and scale-forming ions

    Energy Technology Data Exchange (ETDEWEB)

    Blytas, G.C.; Diaz, Z.

    1989-03-07

    A process is described for the recovery of organic values from aqueous solutions containing both organic values and scale-forming ions, consisting of: electrodialyzing as feed an organic value-containing aqueous solution containing scale-forming ions in a membrane-containing electrodialysis unit to obtain: (1) a concentrate stream containing a major portion of the scale-forming ions from the feed, and (2) a diluate stream containing a major portion of the organic values in the feed, supplying to the side of the membranes within the electrodialysis unit forming the concentrate stream an aqueous carrier stream substantially free of organic values, and in an amount sufficient to substantially reduce or prevent the formation of scale on the membranes, withdrawing the concentrate stream from the electrodialysis unit, fractionating the dilute stream by fractionation-distillation, recycling the overhead fraction as at least a portion of the aqueous carrier stream supplied to the side of the membranes forming the concentrate stream within the electrodialysis unit, and withdrawing the organic product stream from the fractionation distillation step.

  1. Performance assessment of carbonation process integrated with coal fired power plant to reduce CO2 (carbon dioxide) emissions

    International Nuclear Information System (INIS)

    This paper presents a novel approach to recover energy from mineral carbonation process, one of the CCS (carbon capture and storage) technologies, to reduce its additional energy demand and reports the feasibility of integrating a carbonation process with an existing power plant for reducing CO2 (carbon dioxide) emission. A thermodynamic mass and energy flow model of the carbonation process is developed using Matlab/Simulink software for a range of carbonation temperatures using two naturally available feedstocks, namely serpentine and olivine. The CO2 emissions are reduced if a carbonation system is implemented in the power plant, though the power generation efficiency and net power output are reduced too due to the large amount of extra energy required for the grinding of feedstock and the compression of CO2. The existing power plant efficiency was found to be 36.1%. If a carbonation system is incorporated, the plant efficiency reduces to 22% and 24% using serpentine and olivine feedstocks respectively. However, a significant amount of heat energy can be recovered from exothermic reaction of carbonation and carbonated products. The power plant efficiency can be increased to 35% and 34% again, respectively, when energy from carbonation reaction and carbonated products can be recovered appropriately. - Highlights: • Mineral carbonation technology is one of the carbon capture and storage technologies. • Exothermic heat energy can be recovered from mineral carbonation process. • Mineral carbonation process is energy self-sufficient. • Thermodynamic mass and energy balance model is developed for mineral carbonation

  2. Aqueous Processing of Low-Band-Gap Polymer Solar Cells Using Roll-to-Roll Methods

    DEFF Research Database (Denmark)

    Andersen, Thomas Rieks; Larsen-Olsen, Thue Trofod; Andreasen, Birgitta;

    2011-01-01

    . This enabled slot-die coating of high quality films with a dry thickness of 126 ± 19, 500 ± 25, and 612 ± 22 nm P1, P2, and P3, respectively for polymer solar cells. Large area inverted polymer solar cells were thus prepared based on the aqueous inks. The power conversion efficiency (PCE) reached for each...... films. The aqueous dispersions were dialyzed to remove excess detergent and concentrated to a solid content of approximately 60 mg mL–1. The formation of films for solar cells using the aqueous dispersion required the addition of the nonionic detergent FSO-100 at a concentration of 5 mg mL–1...

  3. Influence of enzymes on the oil extraction processes in aqueous media

    Directory of Open Access Journals (Sweden)

    Ricochon Guillaume

    2010-11-01

    Full Text Available The methods of oil aqueous extraction process (AEP assisted by enzymes are, over the last 50 years, an alternative designed to replace traditional methods of extraction using organic solvents. To extract the oil using an AEP, the use of specific enzymes, able to hydrolyze some or all components of seeds, can significantly increase the yields of extraction. Hydrolyzing the different constituents of cell walls (cellulose, hemicellulose, pectins, proteins, etc., enzymes are able to enhance the liberation of the oil. A number of physico-chemical parameters must also be considered for the better expression of the enzymatic mixture, while maintaining the quality of oils and meals. This article presents the various factors influencing the release of oil in aqueous media and the main results obtained by this process on various substrates.

  4. CFD Analysis of Multi-Phase Reacting Transport Phenomena in Discharge Process of Non-Aqueous Lithium-Air Battery

    OpenAIRE

    Yuan, Jinliang; Yu, Jong-Sung; Sundén, Bengt

    2015-01-01

    A computational fluid dynamics (CFD) model is developed for rechargeable non-aqueous electrolyte lithium-air batteries with a partial opening for oxygen supply to the cathode. Multi-phase transport phenomena occurred in the battery are considered, including dissolved lithium ions and oxygen gas in the liquid electrolyte, solid-phase electron transfer in the porous functional materials and liquid-phase charge transport in the electrolyte. These transport processes are coupled with the electroc...

  5. Single step aqueous two-phase extraction for downstream processing of C-phycocyanin from Spirulina platensis

    OpenAIRE

    Chethana, S.; Nayak, Chetan A.; M.C. Madhusudhan; Raghavarao, K. S. M. S.

    2014-01-01

    C-phycocyanin, a natural food colorant, is gaining importance worldwide due to its several medical and pharmaceutical applications. In the present study, aqueous two-phase extraction was shown to be an attractive alternative for the downstream processing of C-phycocyanin from Spirulina platensis. By employing differential partitioning, C-phycocyanin selectively partitioned to the polymer rich (top) phase in concentrated form and contaminant proteins to the salt rich (bottom) phase. This resul...

  6. A New Grade Carbon Black Produced by Thermal Plasma Process

    Institute of Scientific and Technical Information of China (English)

    李娟; 何方方; 罗义文; 印永祥; 戴晓雁; 廖旭

    2003-01-01

    This paper presents a new route about producing carbon black, by which the naturalgas cracking is carried out in the absence of oxygen thanks to an electric energy supply externallygiven by a plasma jet. The carbon black produced by this process has a narrow size distributionand a small average diameter of 38 nm as well as a highly branched aggregate. The higher DBPvalue of 1.40 ml/g shows it should be a high structure carbon black. The FTIR spectra shows thatthere are lots of aromatic c-c bonds and a large amount of nitrogen-containing functional groupson the carbon blacks surface, such as -NH, -CN as well as -CH, -OH, -COOH groups.

  7. Kinetics of Carbon Dioxide with Amines. I. Stopped-Flow Studies in Aqueous Solutions. A Review

    Directory of Open Access Journals (Sweden)

    Couchaux Gabriel

    2014-09-01

    Full Text Available It is possible to find plenty of information about kinetics of reaction between amine and carbone dioxide in the literature. However, there are several experimental techniques and several possible mechanisms which lead to observe sometimes high dispersion of experimental results with various interpretations. A method which enables to compare kinetic constant got by different authors is proposed in this work. First, we present experimental techniques and justify comparison of data obtained by stopped-flow technique. Then, we plot kinetic data for all amine studied in the literature by a power law dependency with the concentration. This representation illustrates some structure-activity relationships and enables to confront experimental results with the different mechanisms. Advantages and limits of each mechanism are discussed. Finally, we justify the choice of the termolecular model to compare data got by different authors. This model leads to a compensation effect which is an argument in favour of this mechanism.

  8. Multi-physical field coupling simulation of TCVI process for preparing carbon/carbon composites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To prepare Carbon/Carbon (C/C) composites with advanced performance, the thermal gradient chemical vapor infiltration (TCVI) process has been optimized by simulation. A 2D axisymmetric unstable model was built, which included convection, conduction, diffusion, densification reactions in the pores and the evolution of the porous medium. The multi-physical field coupling model was solved by finite element method (FEM) and iterative calculation. The time evolution of the fluid, temperature and preform density field were obtained by the calculation. It is indicated that convection strongly affects the temperature field. For the preform of carbon/carbon composites infiltrated for 100 h by TCVI, the radial average densities from simulation agrees well with those from experiment. The model is validated to be reliable and the simulation has capability of forecasting the process.

  9. 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.

  10. Production of activated carbon from biodiesel solid residues: An alternative for hazardous metal sorption from aqueous solution.

    Science.gov (United States)

    Ribeiro, Rita F L; Soares, Vitor C; Costa, Letícia M; Nascentes, Clésia C

    2015-10-01

    In this study, the potential for the sorption of Pb(2+) and Cd(2+) from aqueous solutions using HNO3-treated activated carbon (TAC) obtained from radish press cake (Raphanus sativus L.), a solid residue from biodiesel production, was investigated. Activated carbon (AC) was obtained by physical activation with CO2(g). Chemical modification with HNO3 was employed to increase the sorption capability of the AC. The sorption of Pb(2+) and Cd(2+) was studied in monometallic systems in equilibrium with different metal-ion concentrations (10-400 mg L(-1)). The experimental sorption equilibrium data were fit to the Langmuir and Freundlich isotherm models. The maximum sorption capacity (qmax) obtained for AC from the Langmuir isotherm was 45.5 mg g(-1) for Cd(2+) and 250 mg g(-1) for Pb(2+). Moreover, TAC presented qmax of 166.7 mg g(-1) (1.48 mmol g(-1)) for Cd(2+) and 500.0 mg g(-1) (2.41 mmol g(-1)) for Pb(2+)showing the effect of chemical modification. Sorption-desorption studies showed that the interaction between metals and TAC is reversible and this sorbent can be reused for several consecutive cycles. Furthermore, the sorption of Cd(2+) and Pb(2+) by TAC was not affected by the presence of competing ions. The experimental data obtained in this study indicated that this solid residue is viable for the production of sorbents that remove metals, such as cadmium and lead, from wastewaters and thereby contribute to the sustainable development of the production of biodiesel. PMID:26233585

  11. Amelioration of carbon tetrachloride-induced hepatotoxicity and haemotoxicity by aqueous leaf extract of Cnidoscolus aconitifolius in rats.

    Science.gov (United States)

    Saba, A B; Oyagbemi, A A; Azeez, O I

    2010-01-01

    This study was conducted to explore possible protective effect ofCnidoscolus aconitifolius (CA) leaf extract on carbon tetrachloride (CCl4)-induced hepatotoxicity and haemotoxicity in experimental animal models. Thirty six rats of six per group were used in this study. Group I received 10ml/kg normal saline as control. Group II-VI rats were administered with 1.25ml/kg body weight (bwt) of carbon tetrachloride intraperitonealy. Animals in groups III, IV, V and VI were however pre-treated with aqueous extract of Cnidoscolus aconitifolius at 100, 250, 500 and 750mg/kg body weight (bwt) respectively. Administration of CCL4 in untreated rats led to microcytic hypochromic anaemia, thrombocytopenia, increased erythrocyte fragility and stress induced leucocytosis accompanied with significant increase in neutrophils and decrease in lymphocyte counts. CCl4 also led to significant increase in serum transaminases (ALT and AST) and phosphatase (ALP) respectively compared with control animals. Also, CCL4 produced significant increase in serum blood urea nitrogen (BUN) and creatinine compared with normal rats. Pre-treatment with Cnidoscolus aconitifolius leaf extract brought about significant restoration of the haematological parameters to values that were comparable to those of the control with concomitant decrease in the activities of the marker of hepatic damage enzymes (ALT, AST and ALP), in a dose-dependent manner. Similarly, serum levels of blood urea nitrogen (BUN) and creatinine were also brought to near normal by the CA in a dose-dependent manner. From this study, we conclude that pre-exposure to Cnidoscolus aconitifolius leaf extract considerably reduced the effect of CCl4 on the blood parameters and ameliorated hepatic damage by the haloalkane. PMID:22314953

  12. PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Dady Dadyburjor; Philip R. Biedler; Chong Chen; L. Mitchell Clendenin; Manoj Katakdaunde; Elliot B. Kennel; Nathan D. King; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

    2004-08-31

    This Department of Energy National Energy Technology Laboratory sponsored project developed carbon products, using mildly hydrogenated solvents to extract the organic portion of coal to create synthetic pitches, cokes, carbon foam and carbon fibers. The focus of this effort was on development of lower cost solvents, milder hydrogenation conditions and improved yield in order to enable practical production of these products. This technology is needed because of the long-term decline in production of domestic feedstocks such as petroleum pitch and coal tar pitch. Currently, carbon products represents a market of roughly 5 million tons domestically, and 19 million tons worldwide. Carbon products are mainly derived from feedstocks such as petroleum pitch and coal tar pitch. The domestic supply of petroleum pitch is declining because of the rising price of liquid fuels, which has caused US refineries to maximize liquid fuel production. As a consequence, the long term trend has a decline in production of petroleum pitch over the past 20 years. The production of coal tar pitch, as in the case of petroleum pitch, has likewise declined significantly over the past two decades. Coal tar pitch is a byproduct of metallurgical grade coke (metcoke) production. In this industry, modern metcoke facilities are recycling coal tar as fuel in order to enhance energy efficiency and minimize environmental emissions. Metcoke production itself is dependent upon the production requirements for domestic steel. Hence, several metcoke ovens have been decommissioned over the past two decades and have not been replaced. As a consequence sources of coal tar are being taken off line and are not being replaced. The long-term trend is a reduction in coal tar pitch production. Thus import of feedstocks, mainly from Eastern Europe and China, is on the rise despite the relatively large transportation cost. To reverse this trend, a new process for producing carbon products is needed. The process must be

  13. Respiration and assimilation processes reflected in the carbon isotopic composition of atmospheric carbon dioxide

    International Nuclear Information System (INIS)

    The paper presents diurnal variations of concentration and carbon isotopic composition of atmospheric carbon dioxide caused by respiration and assimilation processes. Air samples were collected during early and late summer in 1998 in unpolluted area (village Guciow located near Roztocze National Park, SE Poland) in three different environments: uncultivated field on a hill, a meadow in the Wieprz river valley and a forest. The effect is very strong during intensive vegetation growth on a sunny day and clear night. The largest diurnal variations in atmospheric CO2 concentration and its carbon isotopic composition in June above the meadow were about 480 ppm and 10 pro mille, respectively. (author)

  14. THE DEVELOPMENT OF AQUEOUS THERMODYNAMIC MODELS: APPLICATION TO WASTE TANK PROCESSING AND VADOSE ZONE ISSUES

    Science.gov (United States)

    The presence of a wide range of radionuclides, metal ions, inorganic ligands, and organic chelating agents combined with the high base and electrolyte concentration in the Hanford waste tanks creates some unique and difficult problems in modeling the aqueous thermodynamics of the...

  15. Development of the Aqueous Processes for Removing NOx from Flue Gases.

    Science.gov (United States)

    Chappell, Gilford A.

    A screening study was conducted to evaluate the capability of aqueous solutions to scrub NOx from the flue gases emitted by stationary power plants fired with fossil fuels. The report summarizes the findings of this laboratory program. The experimental program studied the following media for absorption of NOx from flue gases containing no NOx:…

  16. MD simulation of organics adsorption from aqueous solution in carbon slit-like pores. Foundations of the pore blocking effect

    International Nuclear Information System (INIS)

    The results of systematic studies of organics adsorption from aqueous solutions (at the neutral pH level) in a system of slit-like carbon pores having different sizes and oxygen groups located at the pore mouth are reported. Using molecular dynamics simulations (GROMACS package) the properties of adsorbent–adsorbate (benzene, phenol or paracetamol) as well as adsorbent–water systems are discussed. After the introduction of surface oxygen functionalities, adsorption of organic compounds decreases (in accordance with experimental data) and this is caused by the accumulation of water molecules at pore entrances. The pore blocking effect decreases with the diameter of slits and practically vanishes for widths larger than approx. 0.68 nm. We observed the increase in phenol adsorption with the rise in temperature. Moreover, adsorbed molecules occupy the external surface of the slit pores (the entrances) in the case of oxidized adsorbents. Among the studied molecules benzene, phenol and paracetamol prefer an almost flat orientation and with the rise in the pore width the number of molecules oriented in parallel decreases. The decrease or increase in temperature (with respect to 298 K) leads to insignificant changes of angular orientation of adsorbed molecules. (paper)

  17. Aqueous phase adsorption of cephalexin by walnut shell-based activated carbon: A fixed-bed column study

    Science.gov (United States)

    Nazari, Ghadir; Abolghasemi, Hossein; Esmaieli, Mohamad; Sadeghi Pouya, Ehsan

    2016-07-01

    The walnut shell was used as a low cost adsorbent to produce activated carbon (AC) for the removal of cephalexin (CFX) from aqueous solution. A fixed-bed column adsorption was carried out using the walnut shell AC. The effect of various parameters like bed height (1.5, 2 and 2.5 cm), flow rate (4.5, 6 and 7.5 mL/min) and initial CFX concentration (50, 100 and 150 mg/L) on the breakthrough characteristics of the adsorption system was investigated at optimum pH 6.5. The highest bed capacity of 211.78 mg/g was obtained using 100 mg/L inlet drug concentration, 2 cm bed height and 4.5 mL/min flow rate. Three kinetic models, namely Adam's-Bohart, Thomas and Yoon-Nelson were applied for analysis of experimental data. The Thomas and Yoon-Nelson models were appropriate for walnut shell AC column design under various conditions. The experimental adsorption capacity values were fitted to the Bangham and intra-particle diffusion models in order to propose adsorption mechanisms. The effect of temperature on the degradation of CFX was also studied.

  18. Preparation and properties of multi-wall carbon nanotube/SiC composites by aqueous tape casting

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    MWCNTS/SiC composites were fabricated by aqueous tape casting. High solid content (50 vol%) SiC slurries with sintering additives and multi-wall carbon nanotubes (MWCNTs) as reinforcements were prepared using Tetramethylammonium hydroxide as the dispersant. The stability of MWCNTs/SiC slur-ries was studied and characterized in terms of zeta potential and rheology measurements. The relative density of the composite was about 98% after hot-pressing at 1850℃ (at 25 MPa in Ar for 30 min). The hardness of the composites decreased with the increase in MWCNTs content. The flexural strength and the fracture toughness were 742.17 MPa and 4.63 MPa·m1/2, respectively when the MWCNTs content was 0.25 wt%. Further increase in MWCNTs content to 0.50 wt% did not lead to the increase in mechanical properties. Most of MWCNTs were found to be located at SiC grain boundaries and the pull out of the MWCNTs was observed.

  19. Electrochemical characteristics of the reduced graphene oxide/carbon nanotube/polypyrrole composites for aqueous asymmetric supercapacitors

    Science.gov (United States)

    Peng, Yu-Jung; Wu, Tzu-Ho; Hsu, Chun-Tsung; Li, Shin-Ming; Chen, Ming-Guan; Hu, Chi-Chang

    2014-12-01

    Polypyrrole (PPy) has been polymerized onto reduced graphene oxide/carbon nanotube (rGO/CNT) to form an rGO/CNT/PPy composite using the chemical oxidation method. The electrochemical characteristics of the above composite in various aqueous electrolytes are systematically compared for the asymmetric supercapacitor application. The electrochemical characteristics of rGO/CNT/PPy in the electrolytes containing K+ show improved reversibility and higher stability. Introducing XC-72 in preparing the electrode has been found to enhance the specific capacitance and the cycle stability of rGO/CNT/PPy. The charge storage stability of rGO/CNT/PPy + XC-72 in various potential windows has been evaluated through the potential bias stress test. An asymmetric supercapacitor (ASC) with a positive electrode of Mn3O4 and a negative electrode of rGO/CNT/PPy + XC-72 is successfully demonstrated, which shows specific energy and power of 14. Wh kg-1 and 6.62 kW kg-1 with a cell voltage of 1.6 V. This ASC with a cell voltage of 1.6 V shows excellent charge-discharge cycle stability and ideal capacitive behavior in NaNO3 even after the application of 3250 charge-discharge cycles.

  20. Preparation of activated carbon from rice husk and optimization of adsorption parameters for Cr(vi) removal from aqueous solutions

    International Nuclear Information System (INIS)

    The potential to remove Cromium (Cr)VI from aqueous solution by using activated rice husk was investigated in batch experiments. Rice husk (Oryza sativa) of Kernel Basmati brand was purchased from the rice mill Shadadpur. Rice husk was chemically activated with nitric acid to increase its surface properties. The adsorption process parameters viz., pH, agitation speed, agitation time, adsorbent dose and adsorbate concentration were optimized. There was almost 94.73% sorption of Cr(VI) onto activated rice husk at pH 2. Maximum sorption was achieved at an agitation speed 100 rpm. Kinetic experiments revealed that the equilibrium time was 70 minutes. The amount of sorbent was optimized and remained constant at 0.5 gms. The various characteristics of parameters indicates that activated rice husk could be a good resource material for sorption of Cr(VI) to treat wastewater containing low concentration of the metal. (author)