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Sample records for water oxidation bench-scale

  1. Bench-scale study of the effect of phosphate on an aerobic iron oxidation plant for mine water treatment.

    Science.gov (United States)

    Tischler, Judith S; Wiacek, Claudia; Janneck, Eberhard; Schlömann, Michael

    2014-01-01

    At the opencast pit Nochten acidic iron- and sulfate-rich mine waters are treated biotechnologically in a mine-water treatment plant by microbial iron oxidation. Due to the low phosphate concentration in such waters the treatment plant was simulated in bench-scale to investigate the influence of addition of potassium dihydrogen phosphate on chemical and biological parameters of the mine-water treatment. As a result of the phosphate addition the number of cells increased, which resulted in an increase of the iron oxidation rate in the reactor with phosphate addition by a factor of 1.7 compared to a reference approach without phosphate addition. Terminal restriction fragment length polymorphism (T-RFLP) analysis during the cultivation revealed a shift of the microbial community depending on the phosphate addition. While almost exclusively iron-oxidizing bacteria related to "Ferrovum" sp. were detected with phosphate addition, the microbial community was more diverse without phosphate addition. In the latter case, iron-oxidizing bacteria ("Ferrovum" sp., Acidithiobacillus spp.) as well as non-iron-oxidizing bacteria (Acidiphilium sp.) were identified. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Bench-scale evaluation of ferrous iron oxidation kinetics in drinking water: effect of corrosion control and dissolved organic matter.

    Science.gov (United States)

    Rahman, Safiur; Gagnon, Graham A

    2014-01-01

    Corrosion control strategies are important for many utilities in maintaining water quality from the water treatment plant to the customers' tap. In drinking water with low alkalinity, water quality can become significantly degraded in iron-based pipes if water utilities are not diligent in maintaining proper corrosion control. This article reports on experiments conducted in bicarbonate buffered (5 mg-C/L) synthetic water to determine the effects of corrosion control (pH and phosphate) and dissolved organic matter (DOM) on the rate constants of the Fe(II) oxidation process. A factorial design approach elucidated that pH (P = 0.007, contribution: 42.5%) and phosphate (P = 0.025, contribution: 22.7%) were the statistically significant factors in the Fe(II) oxidation process at a 95% confidence level. The comprehensive study revealed a significant dependency relationship between the Fe(II) oxidation rate constants (k) and phosphate-to- Fe(II) mole ratio. At pH 6.5, the optimum mole ratio was found to be 0.3 to reduce the k values. Conversely, the k values were observed to increase for the phosphate-to- Fe(II) mole ratio > 1. The factorial design approach revealed that chlorine and DOM for the designated dosages did not cause a statistically significant (α = 0.05, P > 0.05)change in rate constants. However, an increment of the chlorine to ferrous iron mole ratio by a factor of ∼ 2.5 resulted in an increase k values by a factor of ∼ 10. This study conclusively demonstrated that the lowest Fe(II) oxidation rate constant was obtained under low pH conditions (pH ≤ 6.5), with chlorine doses less than 2.2 mg/L and with a phosphate-to-Fe(II) mole ratio ≈ 0.3 in the iron water systems.

  3. Management of Acidic Mine Waste Water by Constructed Wetland Treatment Systems: A Bench Scale Study

    OpenAIRE

    Sheoran, A. S.

    2017-01-01

    Constructed wetlands have emerged as a viable option for treatment of acidic mine wastewater. Bench scale experiments were conducted, to evaluate the performance of wetland treatment system, with emergent macrophyte Desmostachya bipinnata and substrate (containing powdered goat manure, wood shavings and soil) for 24, 48, 72, 96 and 168 hours of retention period for different water column heights (100mm, 150mm and 200mm). Within 24 hours of retention period the pH increased from 2.93 to 7.22, ...

  4. Performance study of protective clothing against hot water splashes: from bench scale test to instrumented manikin test.

    Science.gov (United States)

    Lu, Yehu; Song, Guowen; Wang, Faming

    2015-03-01

    Hot liquid hazards existing in work environments are shown to be a considerable risk for industrial workers. In this study, the predicted protection from fabric was assessed by a modified hot liquid splash tester. In these tests, conditions with and without an air spacer were applied. The protective performance of a garment exposed to hot water spray was investigated by a spray manikin evaluation system. Three-dimensional body scanning technique was used to characterize the air gap size between the protective clothing and the manikin skin. The relationship between bench scale test and manikin test was discussed and the regression model was established to predict the overall percentage of skin burn while wearing protective clothing. The results demonstrated strong correlations between bench scale test and manikin test. Based on these studies, the overall performance of protective clothing against hot water spray can be estimated on the basis of the results of the bench scale hot water splashes test and the information of air gap size entrapped in clothing. The findings provide effective guides for the design and material selection while developing high performance protective clothing. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2014.

  5. Full-Scale and Bench-Scale Studies on the Removal of Strontium from Water (abstract)

    Science.gov (United States)

    Strontium (Sr) is a natural and commonly occurring alkaline earth metal which has an oxidation state of +2 under normal environmental conditions. Stable strontium is suspended in water and is dissolved after water runs through rocks and soil. It behaves very similar to calcium. G...

  6. Destruction of hazardous and mixed wastes using mediated electrochemical oxidation in a Ag(II)HNO3 bench scale system

    Energy Technology Data Exchange (ETDEWEB)

    Balazs, B.; Chiba, Z.; Hsu, P.; Lewis, P.; Murguia, L.; Adamson, M.

    1997-02-01

    engineering development have been completed for a pilot plant-scale MEO system, and numerous data have been gathered on the efficacy of the process for a wide variety of anticipated waste components. This presentation will review the data collected at LLNL for a bench scale system based primarily on the use of a Ag(II) mediator in a nitric acid electrolyte; results from several other mediator/acid combinations will be included. Data obtained on the chemical, electrochemical, and engineering aspects will be presented. The topics of organics destruction, transuranic recovery, and some of the ancillary systems will be addressed, and areas requiring further study will be mentioned.

  7. Bench-scale study of active mine water treatment using cement kiln dust (CKD) as a neutralization agent.

    Science.gov (United States)

    Mackie, Allison L; Walsh, Margaret E

    2012-02-01

    The overall objective of this study was to investigate the potential impact on settled water quality of using cement kiln dust (CKD), a waste by-product, to replace quicklime in the active treatment of acidic mine water. Bench-scale experiments were conducted to evaluate the treatment performance of calcium hydroxide (Ca(OH)(2)) slurries generated using four different CKD samples compared to a control treatment with quicklime (CaO) in terms of reducing acidity and metals concentrations in acid mine drainage (AMD) samples taken from the effluent of a lead/zinc mine in Atlantic Canada. Results of the study showed that all of the CKD samples evaluated were capable of achieving greater than 97% removal of total zinc and iron. The amount of solid alkaline material required to achieve pH targets required for neutralization of the AMD was found to be higher for treatment with the CKD slurries compared to the quicklime slurry control experiments, and varied linearly with the free lime content of the CKD. The results of this study also showed that a potential benefit of treating mine water with CKD could be reduced settled sludge volumes generated in the active treatment process, and further research into the characteristics of the sludge generated from the use of CKD-generated calcium hydroxide slurries is recommended. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Thermochemical water-splitting cycle, bench-scale investigations, and process engineering. Final report, February 1977-December 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Norman, J.H.; Besenbruch, G.E.; Brown, L.C.; O' Keefe, D.R.; Allen, C.L.

    1982-05-01

    The sulfur-iodine water-splitting cycle is characterized by the following three reactions: 2H/sub 2/O + SO/sub 2/ + I/sub 2/ ..-->.. H/sub 2/SO/sub 4/ + 2HI; H/sub 2/SO/sub 4/ ..-->.. H/sub 2/O + SO/sub 2/ + 1/2 O/sub 2/; and 2HI ..-->.. H/sub 2/ + I/sub 2/. This cycle was developed at General Atomic after several critical features in the above reactions were discovered. These involved phase separations, catalytic reactions, etc. Estimates of the energy efficiency of this economically reasonable advanced state-of-the-art processing unit produced sufficiently high values (to approx.47%) to warrant cycle development effort. The DOE contract was largely directed toward the engineering development of this cycle, including a small demonstration unit (CLCD), a bench-scale unit, engineering design, and costing. The work has resulted in a design that is projected to produce H/sub 2/ at prices not yet generally competitive with fossil-fuel-produced H/sub 2/ but are projected to be favorably competitive with respect to H/sub 2/ from fossil fuels in the future.

  9. DESTRUCTION OF TETRAPHENYLBORATE IN TANK 48H USING WET AIR OXIDATION BATCH BENCH SCALE AUTOCLAVE TESTING WITH ACTUAL RADIOACTIVE TANK 48H WASTE

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K; Paul Burket, P

    2009-03-31

    Wet Air Oxidation (WAO) is one of the two technologies being considered for the destruction of Tetraphenylborate (TPB) in Tank 48H. Batch bench-scale autoclave testing with radioactive (actual) Tank 48H waste is among the tests required in the WAO Technology Maturation Plan. The goal of the autoclave testing is to validate that the simulant being used for extensive WAO vendor testing adequately represents the Tank 48H waste. The test objective was to demonstrate comparable test results when running simulated waste and real waste under similar test conditions. Specifically: (1) Confirm the TPB destruction efficiency and rate (same reaction times) obtained from comparable simulant tests, (2) Determine the destruction efficiency of other organics including biphenyl, (3) Identify and quantify the reaction byproducts, and (4) Determine off-gas composition. Batch bench-scale stirred autoclave tests were conducted with simulated and actual Tank 48H wastes at SRNL. Experimental conditions were chosen based on continuous-flow pilot-scale simulant testing performed at Siemens Water Technologies Corporation (SWT) in Rothschild, Wisconsin. The following items were demonstrated as a result of this testing. (1) Tetraphenylborate was destroyed to below detection limits during the 1-hour reaction time at 280 C. Destruction efficiency of TPB was > 99.997%. (2) Other organics (TPB associated compounds), except biphenyl, were destroyed to below their respective detection limits. Biphenyl was partially destroyed in the process, mainly due to its propensity to reside in the vapor phase during the WAO reaction. Biphenyl is expected to be removed in the gas phase during the actual process, which is a continuous-flow system. (3) Reaction byproducts, remnants of MST, and the PUREX sludge, were characterized in this work. Radioactive species, such as Pu, Sr-90 and Cs-137 were quantified in the filtrate and slurry samples. Notably, Cs-137, boron and potassium were shown as soluble as a

  10. Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

    Science.gov (United States)

    Wu, Tiehang; Fu, George Yuzhu; Sabula, Michael; Brown, Tommy

    2014-12-01

    Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment.

  11. Coal-fine beneficiation studies of a bench-scale water-only cyclone using artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    V.K. Kalyani; T. Gouri Charan; D.D. Haldar; Amalendu Sinha; Nikkam Suresh [Central Institute of Mining & Fuel Research, Dhanbad (India)

    2008-04-15

    Coal fines generated in Indian coal preparation plants account for 25%-30% of run-of-mine (ROM) coal. Froth flotation is usually practiced in Indian coal washeries for washing the coals to bring down their ash content to acceptable limits. Because of the supply of feed coal from multiple sources, their different characteristics and composition, viz., varying mineralogy and ash content, presence of microfines, and their varying oxidation levels, the fine coal circuits, more often than not, fail to deliver consistent product quality and desired yields. Water-only cyclones have been used in most of the western countries for treating coal and mineral fines below 3 mm. However, the industrial use of these cyclones in India has not yet been put to practice in the coal-washing industry; the primary reason for this being that their design is unsuitable for high-ash content coals and therefore needs to be suitably modified according to the feed material characteristics. Highlighted in the present paper are the results of a case study of beneficiation of high-ash fine coal, using a water-only cyclone. The influence of two of the critical design variables, viz., cyclone length and solid concentration, on which the cyclone performance and the process yield (%) depend to a great extent, is described. Further, based on the experimental data of a water-only cyclone of varying lengths used for below a 3 mm coal beneficiation study, an attempt has also been made to develop a three-layer feed-forward artificial neural network (ANN) model, which is inherently trained using an error-back propagation algorithm. The results evince that the predictions from the ANN model are in good qualitative and quantitative agreement with the experimental observations, thereby validating the applicability and accuracy of the developed ANN model.

  12. In-situ Subaqueous Capping of Mercury-Contaminated Sediments in a Fresh-Water Aquatic System, Part I-Bench-Scale Microcosm Study to Assess Methylmercury Production

    Science.gov (United States)

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absenc...

  13. Hydrogen production with short contact time. Catalytic partial oxidation of hydrocarbons and oxygenated compounds: Recent advances in pilot- and bench-scale testing and process design

    Energy Technology Data Exchange (ETDEWEB)

    Guarinoni, A.; Ponzo, R.; Basini, L. [ENI Refining and Marketing Div., San Donato Milanese (Italy)

    2010-12-30

    ENI R and D has been active for fifteen years in the development of Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technologies for producing Hydrogen/Synthesis Gas. From the beginning the experimental work addressed either at defining the fundamental principles or the technical and economical potential of the technology. Good experimental responses, technical solutions' simplicity and flexibility, favourable techno-economical evaluations promoted the progressive widening of the field of the investigations. From Natural Gas (NG) the range of ''processable'' Hydrocarbons extended to Liquefied Petroleum Gas (LPG) and Gasoils, including those characterised by high levels of unsaturated and sulphurated molecules and, lately, to other compounds with biological origin. The extensive work led to the definition of different technological solutions, grouped as follows: Technology 1: Air Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 2: Enriched Air/Oxygen Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 3: Enriched Air/Oxygen Blown SCT-CPO of Liquid Hydrocarbons and/or Compounds with biological origin Recently, the licence rights on a non-exclusive basis for the commercialisation of SCT-CPO based processes for H{sub 2}/Synthesis gas production from light hydrocarbons with production capacity lower than 5,000 Nm{sup 3}/h of H{sub 2} or 7,500 Nm3/h of syngas have been assigned to two external companies. In parallel, development of medium- and large-scale plant solutions is progressing within the ENI group framework. These last activities are addressed to the utilisation of SCT-CPO for matching the variable Hydrogen demand in several contexts of oil refining operation. This paper will report on the current status of SCT-CPO with a focus on experimental results obtained, either at pilot- and bench- scale level. (orig.)

  14. Removal of Strontium from Drinking Water by Conventional Treatment and Lime Softening in Bench-Scale Studies

    Science.gov (United States)

    The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. There is very little data available on strontium removal from drinking water. As a result, there is an immedia...

  15. Computational fluid dynamics assessment: Volume 2, Isothermal simulations of the METC bench-scale coal-water slurry combustor: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Celik, I.; Chattree, M.

    1988-09-01

    The isothermal turbulent, swirling flow inside the METC pressurized bench-scale combustor has been simulated using ISOPCGC-2. The effects of the swirl numbers, the momentum ratio of the primary to secondary streams, the annular wall thickness, and the quarl angle on the flow and mixing patterns have been investigated. The results that with the present configuration of the combustor, an annular recirculation zone is present up to secondary swirl number of four. A central (on axis) recirculation zone can be obtained by increasing the momentum of the secondary stream by decreasing the annular area at the reactor inlet. The mixing of the primary (fuel carrier) air with the secondary air improves only slightly due to swirl unless a central recirculation zone is present. Good mixing is achieved in the quarl region when a central recirculation zone is present. A preliminary investigation of the influence of placing flow regulators inside the the combustor shows that they influence the flow field significantly and that there is a potential of obtaining optimum flow conditions using these flow regulators. 58 refs., 47 figs., 12 tabs.

  16. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part I—Bench-scale microcosm study to assess methylmercury production

    Energy Technology Data Exchange (ETDEWEB)

    Randall, Paul M., E-mail: randall.paul@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH 45268 (United States); Fimmen, Ryan [Geosyntec Consultants, 150 E. Wilson Bridge Road, Suite 232, Worthington, OH 43085 (United States); Lal, Vivek; Darlington, Ramona [Battelle, 505 King Ave., Columbus, OH 43201 (United States)

    2013-08-15

    Bench-scale microcosm experiments were designed to provide a better understanding of the potential for Hg methylation in sediments from an aquatic environment. Experiments were conducted to examine the function of sulfate concentration, lactate concentration, the presence/absence of an aqueous inorganic Hg spike, and the presence/absence of inoculums of Desulfovibrio desulfuricans, a strain of sulfate-reducing bacteria (SRB) commonly found in the natural sediments of aquatic environments. Incubations were analyzed for both the rate and extent of (methylmercury) MeHg production. Methylation rates were estimated by analyzing MeHg and Hg after 2, 7, 14, 28, and 42 days. The production of metabolic byproducts, including dissolved gases as a proxy for metabolic utilization of carbon substrate, was also monitored. In all treatments amended with lactate, sulfate, Hg, and SRB, MeHg was produced (37 ng/g-sediment dry weight) after only 48 h of incubation and reached a maximum sediment concentration of 127 ng/g-sediment dry weight after the 42 day incubation period. Aqueous phase production of MeHg was observed to be 10 ng/L after 2 day, reaching a maximum observed concentration of 32.8 ng/L after 14 days, and declining to 10.8 ng/L at the end of the incubation period (42 day). The results of this study further demonstrates that, in the presence of an organic carbon substrate, sulfate, and the appropriate consortia of microorganisms, sedimentary Hg will be transformed into MeHg through bacterial metabolism. Further, this study provided the basis for evaluation of an in-situ subaqueous capping strategy that may limit (or potentially enhance) MeHg production. -- Highlights: • Hg methylation by SRB is limited by the depletion of sulfate and carbon. • Hg methylation is sensitive to competition by methanogens for carbon substrate. • In high lactate environment, all lactate was utilized in the microcosms within seven days. • In the absence of adequate metabolic fuel, Me

  17. TASK TECHNICAL AND QUALITY ASSURANCE PLAN FOR OUT-OF-TANK DESTRUCTION OF TETRAPHENYLBORATE VIA WET AIR OXIDATION TECHNOLOGY: PHASE I - BENCH SCALE TESTS

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K

    2006-03-31

    Tank 48H return to service is critical to the processing of high level waste (HLW) at Savannah River Site (SRS). Liquid Waste Disposition (LWD) management has the goal of returning Tank 48H to routine service by January 2010 or as soon as practical. Tank 48H currently holds legacy material containing organic tetraphenylborate (TPB) compounds from the operation of the In-Tank Precipitation process. This material is not compatible with the waste treatment facilities at SRS and must be removed or undergo treatment to destroy the organic compounds before the tank can be returned to Tank Farm service. Tank 48H currently contains {approx}240,000 gallons of alkaline slurry with about 2 wt % potassium and cesium tetraphenylborate (KTPB and CsTPB). The main radioactive component in Tank 48H is {sup 137}Cs. The waste also contains {approx}0.15 wt % Monosodium Titanate (MST) which has adsorbed {sup 90}Sr, U, and Pu isotopes. A System Engineering Evaluation of technologies/ideas for the treatment of TPB identified Wet Air Oxidation (WAO) as a leading alternative technology to the baseline aggregation approach. Over 75 technologies/ideas were evaluated overall. Forty-one technologies/ideas passed the initial screening evaluation. The 41 technologies/ideas were then combined to 16 complete solutions for the disposition of TPB and evaluated in detail. Wet Air Oxidation (WAO) is an aqueous phase process in which soluble or suspended waste components are oxidized using molecular oxygen contained in air. The process operates at elevated temperatures and pressures ranging from 150 to 320 C and 7 to 210 atmospheres, respectively. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). The basic flow scheme for a typical WAO system is as follows. The waste solution or slurry is pumped through a high-pressure feed pump. An air stream containing sufficient oxygen to meet the oxygen requirements of the waste stream is

  18. Bench-Scale and Pilot-Scale Treatment Technologies for the Removal of Total Dissolved Solids from Coal Mine Water: A Review

    Science.gov (United States)

    Coal mine water (CMW) is typically treated to remove suspended solids, acidity, and soluble metals, but high concentrations of total dissolved solids (TDS) have been reported to impact the environment at several CMW discharge points. Consequently, various states have establishe...

  19. Electrodialytic remediation of air pollution control residues in bench scale

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Ferreira, Celia; Hansen, Henrik K.

    2008-01-01

    Air pollution control (APC) residue from municipal solid waste incineration (MSWI) is considered a hazardous waste due to its alkalinity and high content of salts and mobile heavy metals. Various solutions for the handling of APC-residue exist in different regions; however, most commercial....... A system resembling conventional electrodialysis was designed and adjusted to fit the high solids content feed solution (10% APC residue, 90% water). Experiments were made in bench scale with raw residue (natural pH > 12), water pre-residue (natural pH > 12), acid pre-washed residue (pH 10), and acid......-treated residue (pH 2). Our results show that the soluble fraction of the toxic elements Pb, Cu, Cd and Zn was removed from the feed solution and concentrated in the concentrate solution. Furthermore, the leaching (leaching test at L/S 2) of these elements was substantially reduced during treatment (fig. 1...

  20. Development of a bench scale biomass torrefier

    Science.gov (United States)

    Mohd Ja'afar, M. N.; Abd Rahman, A.; Shamsuddin, A. H.

    2013-06-01

    Cofiring biomass with coal has become very popular with power utilities to reduce fossil fuel carbon dioxide (CO2) emission. It is relatively easy to implement on most common pulverised coal plants. However, raw biomass is difficult to utilise and requires upgrading to a higher quality fuel to substitute coal. Upgrading by torrefaction can improve the properties of biomass close to low rank coals suitable for cofiring. In this study, a bench scale torrefier was developed to produce torrefied biomass samples for further studies of its properties and combustion behaviour. The torrefier was developed from a domestic 1600W electric oven. Biomass pellets was then torrefied at 250 °C for 1 hour using this torrefier. Proximate analysis and gross calorific value (GCV) of the torrefied biomass were carried out. The results showed that GCV of the torrefied biomass had increased when compared to raw. The moisture content and volatile matter had decreased, and ash content and fixed carbon had increased as expected.

  1. Design of a Compact and Versatile Bench Scale Tubular Reactor

    Directory of Open Access Journals (Sweden)

    R. Prasad

    2009-06-01

    Full Text Available A compact and versatile laboratory tubular reactor has been designed and fabricated keeping in view of reducing capital cost and minimising energy consumption for gas/vapor-phase heterogeneous catalytic reactions. The reactor is consisted of two coaxial corning glass tubes with a helical coil of glass tube in between the coaxial tubes serving as vaporiser and pre-heater, the catalyst bed is in the inner tube. A schematic diagram of the reactor with detailed dimensions and working principles are described. The attractive feature of the reactor is that the vaporiser, pre-heater and fixed bed reactor are merged in a single compact unit. Thus, the unit minimises separate vaporiser and pre-heater, also avoids separate furnaces used for them and eliminate auxiliary instrumentation such as temperature controller etc. To demonstrate the system operation and illustrate the key features, catalyst screening data and the efficient collection of complete, and accurate intrinsic kinetic data are provided for oxidation of CO over copper chromite catalyst. CO oxidation is an important reaction for auto-exhaust pollution control. The suitability of the versatile nature of the reactor has been ascertained for catalytic reactions where either volatile or vaporizable feeds can be introduced to the reaction zone, e.g. oxidation of iso-octane, reduction of nitric oxide, dehydrogenation of methanol, ethanol and iso-propanol, hydrogenation of nitrobenzene to aniline, etc. Copyright (c 2009 by BCREC. All Rights reserved.[Received: 10 February 2009, Accepted: 9 May 2009][How to Cite: R. Prasad, G. Rattan. (2009. Design of a Compact and Versatile Bench Scale Tubular Reactor. Bulletin of Chemical Reaction Engineering and Catalysis, 4(1: 5-9.  doi:10.9767/bcrec.4.1.1250.5-9][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.1.1250.5-9

  2. Application of bench-scale biocalorimetry to photoautotrophic cultures

    NARCIS (Netherlands)

    Janssen, M.; Patino, R.; Stockar, von U.

    2005-01-01

    Bench-scale biocalorimetry (=1 L) allows for the determination of the metabolic heat flow during bioprocesses under complete control of all process conditions for extended periods of time. It can be combined with a number of on-line and off-line measurement techniques. This combination can

  3. Bench Scale Saltcake Dissolution Test Report

    Energy Technology Data Exchange (ETDEWEB)

    BECHTOLD, D.B.; PACQUET, E.A.

    2000-12-06

    A potential scenario for retrieving saltcake from single shell tanks is the ''Rainbird{reg_sign} sprinkler'' method. Water is distributed evenly across the surface of the saltcake and allowed to percolate by gravity through the waste. The salt dissolves in the water, forming a saturated solution. The saturated liquid is removed by a saltwell pump situated near the bottom of the tank. By this method, there is never a large inventory of liquid in the tank that could pose a threat of leakage. There are many variables or factors that can influence the hydrodynamics of this retrieval process. They include saltcake porosity; saltwell pumping rate; salt dissolution chemistry; factors that could promote flow channeling (e.g. tank walls, dry wells, inclusions or discontinuities in the saltcake); method of water distribution; plug formation due to crystal formations or accumulation of insoluble solids. A brief literature search indicates that very little experimental data exist on these aspects of saltcake dissolution (Wiersma 1996, 1997). The tests reported here were planned (Herting, 2000) to provide preliminary data and information for planning future, scaled-up tests of the sprinkler method.

  4. Lab and Bench-Scale Pelletization of Torrefied Wood Chips

    DEFF Research Database (Denmark)

    Shang, Lei; Nielsen, Niels Peter K.; Stelte, Wolfgang

    2013-01-01

    Combined torrefaction and pelletization is used to increase the fuel value of biomass by increasing its energy density and improving its handling and combustion properties. In the present study, a single-pellet press tool was used to screen for the effects of pellet die temperature, moisture...... content, additive addition, and the degree of torrefaction on the pelletizing properties and pellet quality, i.e., density, static friction, and pellet strength. Results were compared with pellet production using a bench-scale pelletizer. The results indicate that friction is the key factor when scaling...... up from single-pellet press to bench-scale pelletizer. Tuning moisture content or increasing the die temperature did not ease the pellet production of torrefied wood chips significantly. The addition of rapeseed oil as a lubricant reduced the static friction by half and stabilized pellet production...

  5. Fast Pyrolysis Process Development Unit for Validating Bench Scale Data

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Robert C. [Iowa State Univ., Ames, IA (United States). Biorenewables Research Lab.. Center for Sustainable Environmental Technologies. Bioeconomy Inst.; Jones, Samuel T. [Iowa State Univ., Ames, IA (United States). Biorenewables Research Lab.. Center for Sustainable Environmental Technologies. Bioeconomy Inst.

    2010-03-31

    The purpose of this project was to prepare and operate a fast pyrolysis process development unit (PDU) that can validate experimental data generated at the bench scale. In order to do this, a biomass preparation system, a modular fast pyrolysis fluidized bed reactor, modular gas clean-up systems, and modular bio-oil recovery systems were designed and constructed. Instrumentation for centralized data collection and process control were integrated. The bio-oil analysis laboratory was upgraded with the addition of analytical equipment needed to measure C, H, O, N, S, P, K, and Cl. To provide a consistent material for processing through the fluidized bed fast pyrolysis reactor, the existing biomass preparation capabilities of the ISU facility needed to be upgraded. A stationary grinder was installed to reduce biomass from bale form to 5-10 cm lengths. A 25 kg/hr rotary kiln drier was installed. It has the ability to lower moisture content to the desired level of less than 20% wt. An existing forage chopper was upgraded with new screens. It is used to reduce biomass to the desired particle size of 2-25 mm fiber length. To complete the material handling between these pieces of equipment, a bucket elevator and two belt conveyors must be installed. The bucket elevator has been installed. The conveyors are being procured using other funding sources. Fast pyrolysis bio-oil, char and non-condensable gases were produced from an 8 kg/hr fluidized bed reactor. The bio-oil was collected in a fractionating bio-oil collection system that produced multiple fractions of bio-oil. This bio-oil was fractionated through two separate, but equally important, mechanisms within the collection system. The aerosols and vapors were selectively collected by utilizing laminar flow conditions to prevent aerosol collection and electrostatic precipitators to collect the aerosols. The vapors were successfully collected through a selective condensation process. The combination of these two mechanisms

  6. Bench-Scale Filtration Testing in Support of the Pretreatment Engineering Platform (PEP)

    Energy Technology Data Exchange (ETDEWEB)

    Billing, Justin M.; Daniel, Richard C.; Kurath, Dean E.; Peterson, Reid A.

    2009-09-28

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed and operated as part of a plan to respond to issue M12, “Undemonstrated Leaching Processes.” The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP testing program specifies that bench-scale testing is to be performed in support of specific operations, including filtration, caustic leaching, and oxidative leaching.

  7. Performance evaluation of the DCMD desalination process under bench scale and large scale module operating conditions

    KAUST Repository

    Francis, Lijo

    2014-04-01

    The flux performance of different hydrophobic microporous flat sheet commercial membranes made of poly tetrafluoroethylene (PTFE) and poly propylene (PP) was tested for Red Sea water desalination using the direct contact membrane distillation (DCMD) process, under bench scale (high δT) and large scale module (low δT) operating conditions. Membranes were characterized for their surface morphology, water contact angle, thickness, porosity, pore size and pore size distribution. The DCMD process performance was optimized using a locally designed and fabricated module aiming to maximize the flux at different levels of operating parameters, mainly feed water and coolant inlet temperatures at different temperature differences across the membrane (δT). Water vapor flux of 88.8kg/m2h was obtained using a PTFE membrane at high δT (60°C). In addition, the flux performance was compared to the first generation of a new locally synthesized and fabricated membrane made of a different class of polymer under the same conditions. A total salt rejection of 99.99% and boron rejection of 99.41% were achieved under extreme operating conditions. On the other hand, a detailed water characterization revealed that low molecular weight non-ionic molecules (ppb level) were transported with the water vapor molecules through the membrane structure. The membrane which provided the highest flux was then tested under large scale module operating conditions. The average flux of the latter study (low δT) was found to be eight times lower than that of the bench scale (high δT) operating conditions.

  8. 100 Area groundwater biodenitrification bench-scale treatability study procedures

    Energy Technology Data Exchange (ETDEWEB)

    Peyton, B.M.; Martin, K.R.

    1993-05-01

    This document describes the methodologies and procedures for conducting the bench-scale biodenitrification treatability tests at Pacific Northwest Laboratory{sup a} (PNL). Biodenitrification is the biological conversion of nitrate and nitrite to gaseous nitrogen. The tests will use statistically designed batch studies to determine if biodenitrification can reduce residual nitrate concentrations to 45 mg/L, the current maximum contaminant level (MCL). These tests will be carried out in anaerobic flasks with a carbon source added to demonstrate nitrate removal. At the pilot scale, an incremental amount of additional carbon will be required to remove the small amount of oxygen present in the incoming groundwater. These tests will be conducted under the guidance of Westinghouse Hanford Company (WHC) and the 100-HR-3 Groundwater Treatability Test Plan (DOE/RL-92-73) and the Treatability Study Program Plan (DOE/RL-92-48) using groundwater from 100-HR-3. In addition to the procedures, requirements for safety, quality assurance, reporting, and schedule are given. Appendices include analytical procedures, a Quality Assurance Project Plan, a Health and Safety Plan, and Applicable Material Data Safety Sheets. The procedures contained herein are designed specifically for the 100-HR-3 Groundwater Treatability Test Plan, and while the author believes that the methods described herein are scientifically valid, the procedures should not be construed or mistaken to be generally applicable to any other treatability study.

  9. Bench-scale co-processing economic assessment. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Gala, H.B.; Marker, T.L.; Miller, E.N.

    1994-11-01

    The UOP Co-Processing scheme is a single-stage slurry catalyzed process in which petroleum vacuum resid and coal are simultaneously upgraded to a high-quality synthetic oil. A highly active dispersed catalyst has been developed which enables the operation of the co-processing unit at relatively moderate and high temperatures and relatively high pressure. Under the current contract, a multi-year research program was undertaken to study the technical and economic feasibility of this technology. All the contractual tasks were completed. Autoclave experiments were carried out to evaluate dispersed vanadium catalysts, molybdenum catalysts, and a less costly UOP-proprietary catalyst preparation technique. Autoclave experiments were also carried out in support of the continuous pilot plant unit operation and to study the effects of the process variables (pressure, temperature, and metal loading on the catalyst). A total of 24 continuous pilot plant runs were made. Research and development efforts during the pilot plant operations were concentrated on addressing the cost effectiveness of the UOP single-stage slurry catalyzed co-processing concept based on UOP experience gained in the previous DOE contract. To this end, effect of catalyst metal concentration was studied and a highly-active Mo-based catalyst was developed. This catalyst enabled successful long-term operation (924 hours) of the continuous bench-scale plant at highly severe operating conditions of 3,000 psig, 465{degree}C temperature, and 2:1 resid-to-MAF (moisture- and ash-free) coal ratio with 0.1 wt % active metal. The metal loading of the catalyst was low enough to consider the catalyst as a disposable slurry catalyst. Also, liquid recycle was incorporated in the pilot plant design to increase the, reactor back mixing and to increase the flow of liquid through the reactor (to introduce turbulence in the reactor) and to represent the design of a commercial-scale reactor.

  10. Uncertainty Quantification Analysis of Both Experimental and CFD Simulation Data of a Bench-scale Fluidized Bed Gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Shahnam, Mehrdad [National Energy Technology Lab. (NETL), Morgantown, WV (United States). Research and Innovation Center, Energy Conversion Engineering Directorate; Gel, Aytekin [ALPEMI Consulting, LLC, Phoeniz, AZ (United States); Subramaniyan, Arun K. [GE Global Research Center, Niskayuna, NY (United States); Musser, Jordan [National Energy Technology Lab. (NETL), Morgantown, WV (United States). Research and Innovation Center, Energy Conversion Engineering Directorate; Dietiker, Jean-Francois [West Virginia Univ. Research Corporation, Morgantown, WV (United States)

    2017-10-02

    Adequate assessment of the uncertainties in modeling and simulation is becoming an integral part of the simulation based engineering design. The goal of this study is to demonstrate the application of non-intrusive Bayesian uncertainty quantification (UQ) methodology in multiphase (gas-solid) flows with experimental and simulation data, as part of our research efforts to determine the most suited approach for UQ of a bench scale fluidized bed gasifier. UQ analysis was first performed on the available experimental data. Global sensitivity analysis performed as part of the UQ analysis shows that among the three operating factors, steam to oxygen ratio has the most influence on syngas composition in the bench-scale gasifier experiments. An analysis for forward propagation of uncertainties was performed and results show that an increase in steam to oxygen ratio leads to an increase in H2 mole fraction and a decrease in CO mole fraction. These findings are in agreement with the ANOVA analysis performed in the reference experimental study. Another contribution in addition to the UQ analysis is the optimization-based approach to guide to identify next best set of additional experimental samples, should the possibility arise for additional experiments. Hence, the surrogate models constructed as part of the UQ analysis is employed to improve the information gain and make incremental recommendation, should the possibility to add more experiments arise. In the second step, series of simulations were carried out with the open-source computational fluid dynamics software MFiX to reproduce the experimental conditions, where three operating factors, i.e., coal flow rate, coal particle diameter, and steam-to-oxygen ratio, were systematically varied to understand their effect on the syngas composition. Bayesian UQ analysis was performed on the numerical results. As part of Bayesian UQ analysis, a global sensitivity analysis was performed based on the simulation results, which shows

  11. Domestic Wastewater Reuse in Concrete Using Bench-Scale Testing and Full-Scale Implementation

    Directory of Open Access Journals (Sweden)

    Ayoup M. Ghrair

    2016-08-01

    Full Text Available Demand for fresh water by the construction sector is expected to increase due to the high increase in the growth of construction activities in Jordan. This study aims to evaluate the potential of scale-up of the application of treated domestic wastewater in concrete from bench-scale to a full-scale. On the lab scale, concrete and mortar mixes using Primary and Secondary Treated Wastewater (PTW, STW and Distilled Water (DW were cast and tested after various curing ages (7, 28, 120, and 200 days. Based on wastewater quality, according to IS 456-2000, the STW is suitable for mortar and concrete production. Mortar made with STW at curing time up to 200 days has no significant negative effect on the mortar’s compressive strength. Conversely, the PTW exceeded the maximum permissible limits of total organic content and E coli. for concrete mixing-water. Using PTW results, a significant increase in the initial setting time of up to 16.7% and a decrease in the concrete workability are observed. In addition, using PTW as mixing water led to a significant reduction in the compressive strength up to 19.6%. The results that came out from scaling up to real production operation of ready-mix concrete were in harmony with the lab-scale results.

  12. Hydrogen generation from bioethanol reforming : bench-scale unit performance with Cu/Nb2O5 catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Machado, N.R.C.F.; Rizzo, R.C.P.; Calsavara, V.; Takahashi, F.; Almeida, A.A.; Melo, F.R. de; Zschornack, M.A.; Bessani, A.N.; Rodrigues, R.M.O. [State University of Maringa, Maringa (Brazil). Dept. of Chemical Engineering Lab. of Catalysis; Schmal, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Centro de Tecnologia, Graduate School and Research in Engineering Alberto Luiz Coimbra Institute; Cantao, M.P. [Institute of Technology for Development, Curitiba (Brazil). Dept. of Materials

    2003-07-01

    A series of experiments have been conducted to produce hydrogen from ethanol reforming. This paper presents the bench-scale study unit that uses a 5 per cent copper-niobium2oxygen5 (Cu/Nb2O5) catalyst previously selected in a micro reactor. X-ray diffraction analysis revealed that the catalyst contained copper oxide in an amorphous form and that the Nb2O5 was highly crystalline. The calcinated catalyst was analysed with X-ray photoelectron spectroscopy and showed that 35 per cent of total copper was on the surface as Cu{sup I} (55 per cent) and Cu{sup II} (45 per cent). The surface area was mainly comprised of meso and macro pores. There was a two-step reduction of Cu{sup II} to Cu at 245 and 306 degrees C, as shown by temperature programmed reduction, as well as a 6 per cent reduction of Nb2O5. An internal reactor with 16 grams (g) of catalyst pellets was contained in the reaction unit. To optimize hydrogen production, reaction temperature and feed rate were varied, and the major by-product was carbon dioxide. Reagents (water and ethanol) were fed into and vaporized in, an electric pre-heater in stoichiometric proportion. Mean conversion increased from 17 per cent to 35 per cent through an increase of reaction temperature from 300 to 400 degrees C. Minor by-products were detected in the form of ethene and ethyl ether. 9 refs., 3 tabs., 4 figs.

  13. Continuous bench-scale slurry catalyst testing direct coal liquefaction rawhide sub-bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, R.F.; Coless, L.A.; Davis, S.M. [and others

    1995-12-31

    In 1992, the Department of Energy (DOE) sponsored research to demonstrate a dispersed catalyst system using a combination of molybdenum and iron precursors for direct coal liquefaction. This dispersed catalyst system was successfully demonstrated using Black Thunder sub-bituminous coal at Wilsonville, Alabama by Southern Electric International, Inc. The DOE sponsored research continues at Exxon Research and Development Laboratories (ERDL). A six month continuous bench-scale program using ERDL`s Recycle Coal Liquefaction Unit (RCLU) is planned, three months in 1994 and three months in 1995. The initial conditions in RCLU reflect experience gained from the Wilsonville facility in their Test Run 263. Rawhide sub-bituminous coal which is similar to the Black Thunder coal tested at Wilsonville was used as the feed coal. A slate of five dispersed catalysts for direct coal liquefaction of Rawhide sub-bituminous coal has been tested. Throughout the experiments, the molybdenum addition rate was held constant at 100 wppm while the iron oxide addition rate was varied from 0.25 to 1.0 weight percent (dry coal basis). This report covers the 1994 operations and accomplishments.

  14. Bench-scale arc melter for R&D in thermal treatment of mixed wastes

    Energy Technology Data Exchange (ETDEWEB)

    Kong, P.C.; Grandy, J.D.; Watkins, A.D.; Eddy, T.L.; Anderson, G.L.

    1993-05-01

    A small dc arc melter was designed and constructed to run bench-scale investigations on various aspects of development for high-temperature (1,500-1,800{degrees}C) processing of simulated transuranic-contaminated waste and soil located at the Radioactive Waste Management Complex (RWMC). Several recent system design and treatment studies have shown that high-temperature melting is the preferred treatment. The small arc melter is needed to establish techniques and procedures (with surrogates) prior to using a similar melter with the transuranic-contaminated wastes in appropriate facilities at the site. This report documents the design and construction, starting and heating procedures, and tests evaluating the melter`s ability to process several waste types stored at the RWMC. It is found that a thin graphite strip provides reliable starting with initial high current capability for partially melting the soil/waste mixture. The heating procedure includes (1) the initial high current-low voltage mode, (2) a low current-high voltage mode that commences after some slag has formed and arcing dominates over the receding graphite conduction path, and (3) a predominantly Joule heating mode during which the current can be increased within the limits to maintain relatively quiescent operation. Several experiments involving the melting of simulated wastes are discussed. Energy balance, slag temperature, and electrode wear measurements are presented. Recommendations for further refinements to enhance its processing capabilities are identified. Future studies anticipated with the arc melter include waste form processing development; dissolution, retention, volatilization, and collection for transuranic and low-level radionuclides, as well as high vapor pressure metals; electrode material development to minimize corrosion and erosion; refractory corrosion and/or skull formation effects; crucible or melter geometry; metal oxidation; and melt reduction/oxidation (redox) conditions.

  15. Bench-scale biofilter for removing ammonia from poultry house exhaust.

    Science.gov (United States)

    Shah, S B; Basden, T J; Bhumbla, D K

    2003-01-01

    A bench-scale biofilter was evaluated for removing ammonia (NH3) from poultry house exhaust. The biofilter system was equipped with a compost filter to remove NH3 and calcium oxide (CaO) filter to remove carbon dioxide (CO2). Removal of NH3 and CO2 from poultry house exhaust could allow treated air with residual heat to be recirculated back into the poultry house to conserve energy during winter months. Apart from its use as a plant nutrient, NH3 removal from poultry house exhaust could lessen the adverse environmental impacts of NH3 emissions. Ammonia and CO2 were measured daily with gas detector tubes while temperatures in the poultry pen and compost filter were monitored to evaluate the thermal impact of the biofilter on treated air. During the first 37 days of the 54-day study, exhaust air from 33 birds housed in a pen was treated in the biofilter; for the final 17 days, NH3-laden exhaust, obtained by applying urea to the empty pen was treated in the biofilter. The biofilter system provided near-complete attenuation of a maximum short-term NH3 concentration of 73 ppm. During the last 17 days, with a mean influent NH3 concentration of 26 ppm, the biofilter provided 97% attenuation. The CaO filter was effective in attenuating CO2. Compared with a biofilter sized only for NH3 removal, an oversized biofilter would be required to provide supplemental heat to the treated air through exothermic biochemical reactions in the compost. The biofilter could conserve energy in poultry production and capture NH3 for use as plant nutrient. Based on this study, a house for 27,000 broilers would require a compost filter with a volume of approximately 34 m3.

  16. Bench scale demonstration of the Supermethanol concept : The synthesis of methanol from glycerol derived syngas

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2012-01-01

    An integrated process for the synthesis of methanol from aqueous glycerol involving reforming of the feed to syngas followed by methanol synthesis is successfully demonstrated in a continuous bench scale unit. Glycerol reforming was carried out at pressures of 24-27 MPa and temperatures of 948-998 K

  17. DEGRADATION OF POLYNUCLEAR AROMATIC HYDROCARBONS UNDER BENCH-SCALE COMPOST CONDITIONS

    Science.gov (United States)

    The relationship between biomass growth and degradation of polynuclear aromatic hydrocarbons (PAHs) in soil, and subsequent toxicity reduction, was evaluated in 10 in-vessel, bench-scale compost units. Field soil was aquired from the Reilly Tar and Chemical Company Superfund site...

  18. MULTICOMPONENT AEROSOL DYNAMICS OF THE PB-O2 SYSTEM IN A BENCH SCALE FLAME INCINERATOR

    Science.gov (United States)

    A study was carried out to understand the formation and growth of lead particles in a flame incinerator. A bench scale flame incinerator was used to perform controlled experiments with lead acetate as a test compound. A dilution probe in conjunction with real-time aerosol instrum...

  19. Development of a bench-scale fluidized bed combustor (FBC) for ...

    African Journals Online (AJOL)

    coconut shell) using the relevant ASTM guidelines. For coal combustion, the characteristic quantities measured from the bench-scale fluidized bed combustion include a mean NOx emission of 455.35, 376.69, 323.35 and 277.35 ppm for a ...

  20. Bench-scale Kinetics Study of Mercury Reactions in FGD Liquors

    Energy Technology Data Exchange (ETDEWEB)

    Gary Blythe; John Currie; David DeBerry

    2008-03-31

    This document is the final report for Cooperative Agreement DE-FC26-04NT42314, 'Kinetics Study of Mercury Reactions in FGD Liquors'. The project was co-funded by the U.S. DOE National Energy Technology Laboratory and EPRI. The objective of the project has been to determine the mechanisms and kinetics of the aqueous reactions of mercury absorbed by wet flue gas desulfurization (FGD) systems, and develop a kinetics model to predict mercury reactions in wet FGD systems. The model may be used to determine optimum wet FGD design and operating conditions to maximize mercury capture in wet FGD systems. Initially, a series of bench-top, liquid-phase reactor tests were conducted and mercury species concentrations were measured by UV/visible light spectroscopy to determine reactant and byproduct concentrations over time. Other measurement methods, such as atomic absorption, were used to measure concentrations of vapor-phase elemental mercury, that cannot be measured by UV/visible light spectroscopy. Next, a series of bench-scale wet FGD simulation tests were conducted. Because of the significant effects of sulfite concentration on mercury re-emission rates, new methods were developed for operating and controlling the bench-scale FGD experiments. Approximately 140 bench-scale wet FGD tests were conducted and several unusual and pertinent effects of process chemistry on mercury re-emissions were identified and characterized. These data have been used to develop an empirically adjusted, theoretically based kinetics model to predict mercury species reactions in wet FGD systems. The model has been verified in tests conducted with the bench-scale wet FGD system, where both gas-phase and liquid-phase mercury concentrations were measured to determine if the model accurately predicts the tendency for mercury re-emissions. This report presents and discusses results from the initial laboratory kinetics measurements, the bench-scale wet FGD tests, and the kinetics modeling

  1. Goethite Bench-scale and Large-scale Preparation Tests

    Energy Technology Data Exchange (ETDEWEB)

    Josephson, Gary B.; Westsik, Joseph H.

    2011-10-23

    ferrous ion, Fe{sup 2+}-Fe{sup 2+} is oxidized to Fe{sup 3+} - in the presence of goethite seed particles. Rhenium does not mimic that process; it is not a strong enough reducing agent to duplicate the TcO{sub 4}{sup -}/Fe{sup 2+} redox reactions. Laboratory tests conducted in parallel with these scaled tests identified modifications to the liquid chemistry necessary to reduce ReO{sub 4}{sup -} and capture rhenium in the solids at levels similar to those achieved by Um (2010) for inclusion of Tc into goethite. By implementing these changes, Re was incorporated into Fe-rich solids for testing at VSL. The changes also changed the phase of iron that was in the slurry product: rather than forming goethite ({alpha}-FeOOH), the process produced magnetite (Fe{sub 3}O{sub 4}). Magnetite was considered by Pacific Northwest National Laboratory (PNNL) and VSL to probably be a better product to improve Re retention in the melter because it decomposes at a higher temperature than goethite (1538 C vs. 136 C). The feasibility tests at VSL were conducted using Re-rich magnetite. The tests did not indicate an improved retention of Re in the glass during vitrification, but they did indicate an improved melting rate (+60%), which could have significant impact on HLW processing. It is still to be shown whether the Re is a solid solution in the magnetite as {sup 99}Tc was determined to be in goethite.

  2. GLYPHOSATE REMOVAL FROM DRINKING WATER

    Science.gov (United States)

    Activated-carbon, oxidation, conventional-treatment, filtration, and membrane studies are conducted to determine which process is best suited to remove the herbicide glyphosate from potable water. Both bench-scale and pilot-scale studies are completed. Computer models are used ...

  3. Molecular water oxidation catalysis

    CERN Document Server

    Llobet, Antoni

    2014-01-01

    Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most importan

  4. Steam Reforming, 6-in. Bench-Scale Design and Testing Project -- Technical and Functional Requirements Description

    Energy Technology Data Exchange (ETDEWEB)

    Losinski, Sylvester John; Marshall, Douglas William

    2002-08-01

    Feasibility studies and technology development work are currently being performed on several processes to treat radioactive liquids and solids currently stored at the Idaho Nuclear Technology and Engineering Center (INTEC), located within the Idaho National Engineering and Environmental Laboratory (INEEL). These studies and development work will be used to select a treatment process for treatment of the radioactive liquids and solids to meet treatment milestones of the Settlement Agreement between the Department of Energy and the State of Idaho. One process under consideration for treating the radioactive liquids and solids, specifically Sodium-Bearing Waste (SBW) and tank heel solids, is fluid bed steam reforming (FBSR). To support both feasibility and development studies a bench-scale FBSR is being designed and constructed. This report presents the technical and functional requirements, experimental objectives, process flow sheets, and equipment specifications for the bench-scale FBSR.

  5. Embedded Sensors and Controls to Improve Component Performance and Reliability -- Bench-scale Testbed Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Drira, Anis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Reed, Frederick K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Embedded instrumentation and control systems that can operate in extreme environments are challenging due to restrictions on sensors and materials. As a part of the Department of Energy's Nuclear Energy Enabling Technology cross-cutting technology development programs Advanced Sensors and Instrumentation topic, this report details the design of a bench-scale embedded instrumentation and control testbed. The design goal of the bench-scale testbed is to build a re-configurable system that can rapidly deploy and test advanced control algorithms in a hardware in the loop setup. The bench-scale testbed will be designed as a fluid pump analog that uses active magnetic bearings to support the shaft. The testbed represents an application that would improve the efficiency and performance of high temperature (700 C) pumps for liquid salt reactors that operate in an extreme environment and provide many engineering challenges that can be overcome with embedded instrumentation and control. This report will give details of the mechanical design, electromagnetic design, geometry optimization, power electronics design, and initial control system design.

  6. Design and fabrication of a glovebox for the Plasma Hearth Process radioactive bench-scale system

    Energy Technology Data Exchange (ETDEWEB)

    Wahlquist, D.R. [Argonne National Lab., Idaho Falls, ID (United States). Technology Development Div.

    1996-07-01

    This paper presents some of the design considerations and fabrication techniques for building a glovebox for the Plasma Hearth Process (PHP) radioactive bench-scale system. The PHP radioactive bench-scale system uses a plasma torch to process a variety of radioactive materials into a final vitrified waste form. The processed waste will contain plutonium and trace amounts of other radioactive materials. The glovebox used in this system is located directly below the plasma chamber and is called the Hearth Handling Enclosure (HHE). The HHE is designed to maintain a confinement boundary between the processed waste and the operator. Operations that take place inside the HHE include raising and lowering the hearth using a hydraulic lift table, transporting the hearth within the HHE using an overhead monorail and hoist system, sampling and disassembly of the processed waste and hearth, weighing the hearth, rebuilding a hearth, and sampling HEPA filters. The PHP radioactive bench-scale system is located at the TREAT facility at Argonne National Laboratory-West in Idaho Falls, Idaho.

  7. Bench Scale Process for Low Cost CO2 Capture Using a Phase-Changing Absorbent: Final Scientific/Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Westendorf, Tiffany [GE Global Research, Niskayuna, New York (United States); Buddle, Stanlee [GE Global Research, Niskayuna, New York (United States); Caraher, Joel [GE Global Research, Niskayuna, New York (United States); Chen, Wei [GE Global Research, Niskayuna, New York (United States); Doherty, Mark [GE Global Research, Niskayuna, New York (United States); Farnum, Rachel [GE Global Research, Niskayuna, New York (United States); Giammattei, Mark [GE Global Research, Niskayuna, New York (United States); Hancu, Dan [GE Global Research, Niskayuna, New York (United States); Miebach, Barbara [GE Global Research, Niskayuna, New York (United States); Perry, Robert [GE Global Research, Niskayuna, New York (United States); Rubinsztajn, Gosia; Spiry, Irina; Wilson, Paul; Wood, Benjamin

    2017-05-31

    unit operations in the process. The bench scale unit operations were assembled into a continuous system to support steady state system testing. In the third budget period of the project, continuous system testing was conducted, including closed-loop operation of the absorber and desober systems. Slurries of GAP-0/GAP-0 carbamate/water mixtures produced in the absorber were pumped successfully to the desorber unit, and regenerated solvent was returned to the absorber. A techno-economic analysis, EH&S risk assessment, and solvent manufacturability study were completed.

  8. INTEGRATION OF PHOTOCATALYTIC OXIDATION WITH AIR STRIPPING OF CONTAMINATED AQUIFERS

    Science.gov (United States)

    Bench scale laboratory studies and pilot scale studies in a simulated field-test situation were performed to evaluate the integration of gas-solid ultaviolet (UV) photocatalytic oxidation (PCO) downstream if an air stripper unit as a technology for cost-effectively treating water...

  9. Bench-Scale Evaluation of the Genifuel Hydrothermal Processing Technology for Wastewater Solids

    Energy Technology Data Exchange (ETDEWEB)

    Marrone, Philip A.; Elliott, Douglas C.; Billing, Justin M.; Hallen, Richard T.; Hart, Todd R.; Kadota, Paul; Moeller, Jeff C.; Randel, Margaaret A.; Schmidt, Andrew J.

    2017-10-03

    Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of the Genifuel hydrothermal process technology for handling municipal wastewater sludge. HTL tests were conducted at 300-350°C and 20 MPa on three different feeds: primary sludge (11.9 wt% solids), secondary sludge (9.7 wt% solids), and post-digester sludge (also referred to as digested solids) (16.0 wt% solids). Corresponding CHG tests were conducted at 350°C and 20 MPa on the HTL aqueous phase output using a ruthenium based catalyst. A comprehensive analysis of all feed and effluent phases was also performed. Total mass and carbon balances closed to within ± 15% in all but one case. Biocrude yields from HTL tests were 37%, 25%, and 34% for primary sludge, secondary sludge, and digested solids feeds, respectively. The biocrude yields accounted for 59%, 39%, and 49% of the carbon in the feed for primary sludge, secondary sludge, and digested solids feeds, respectively. Biocrude composition and quality were comparable to that seen with biocrudes generated from algae feeds. Subsequent hydrotreating (i.e., upgrading) of the biocrude produced from primary sludge and digested solids resulted in a product with comparable physical and chemical properties to petroleum crude oil. CHG product gas consisted primarily of methane, with methane yields (relative to CHG input) on a carbon basis of 47%, 61%, and 64% for aqueous feeds that were the output of HTL tests with primary sludge, secondary sludge, and digested solids, respectively. Siloxane concentrations in the CHG product gas were below the detection limit and well below fuel input composition limits set by several engine manufacturers. Relative to that of the sludge feeds, the HTL-CHG process resulted in a reduction in chemical oxygen demand (COD) of greater than 99.9% and a reduction in residual solids for disposal of 94-99%. The test results, as a whole, support

  10. Hydrogen generation from bioethanol reforming: bench-scale unit performance with Cu/Nb{sub 2}O{sub 5} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes Machado, N.R.C. [State Univ. of Maringa (UEM), Chemical Engineering Dept., Lab. of Catalysis, Maringa (Brazil); Schmal, M. [PEQ/COPPE/UFRJ Cidade Univ., Centro de Tecnologia, Graduate School and Research in Engineering Alberto Luiz Coimbra Institute, Rio De Janeiro (Brazil); Cantao, M.P. [LACTEC, Dept. of Materials, Inst. of Technology for Development, Curitiba (Brazil)] [and others

    2003-07-01

    As an alternative route for hydrogen production, ethanol reforming was studied in a bench-scale unit using a 5%Cu/Nb{sub 2}O{sub 5} catalyst previously selected in a micro reactor. X-Ray Diffraction analysis has shown that this catalyst contains copper oxide in an amorphous form, or in particles smaller than 20 nm, while the Nb{sub 2}O{sub 5} is highly crystalline. Analysis of the calcinated catalyst by X-Ray Photoelectron Spectroscopy revealed that 35% of total copper was on the surface as Cu{sup I} (55%) or Cu{sup II} (45%). The catalyst presented a low surface area (35 m{sup 2}/g), mainly from meso and macropores, as textural analysis revealed. Temperature Programmed Reduction showed a two-step reduction of Cu{sup II} to Cu, at 245{sup o}C and 306{sup o}C. It was also observed the reduction of 6% of Nb{sub 2}O{sub 5}. The reaction unit consisted of an integral reactor with 16 g of catalyst pellets, approximately 3 mm x 5 mm in size. Reaction temperature and feed rate were varied to optimize hydrogen production, with CO{sub 2} as the main byproduct. Reagents (water and ethanol) in stoichiometric proportion were fed into an electric pre-heater and vaporized. An increase on reaction temperature from 300{sup o}C to 400{sup o}C has led to an increase in mean conversion from 17% to 35%. Ethene and ethyl ether were also detected as minor byproducts. (author)

  11. Screening of phenylpyruvic acid producers and optimization of culture conditions in bench scale bioreactors.

    Science.gov (United States)

    Coban, Hasan B; Demirci, Ali; Patterson, Paul H; Elias, Ryan J

    2014-11-01

    Alpha keto acids are deaminated forms of amino acids that have received significant attention as feed and food additives in the agriculture and medical industries. To date, their production has been commonly performed at shake-flask scale with low product concentrations. In this study, production of phenylpyruvic acid (PPA), which is the alpha keto acid of phenylalanine was investigated. First, various microorganisms were screened to select the most efficient producer. Thereafter, growth parameters (temperature, pH, and aeration) were optimized in bench scale bioreactors to maximize both PPA and biomass concentration in bench scale bioreactors, using response surface methodology. Among the four different microorganisms evaluated, Proteus vulgaris was the most productive strain for PPA production. Optimum temperature, pH, and aeration conditions were determined as 34.5 °C, 5.12, and 0.5 vvm for PPA production, whereas 36.9 °C, pH 6.87, and 0.96 vvm for the biomass production. Under these optimum conditions, PPA concentration was enhanced to 1,054 mg/L, which was almost three times higher than shake-flask fermentation concentrations. Moreover, P. vulgaris biomass was produced at 3.25 g/L under optimum conditions. Overall, this study demonstrated that optimization of growth parameters improved PPA production in 1-L working volume bench-scale bioreactors compared to previous studies in the literature and was a first step to scale up the production to industrial production.

  12. Accumulation of uranium, cesium, and radium by microbial cells: bench-scale studies

    Energy Technology Data Exchange (ETDEWEB)

    Strandberg, G.W.; Shumate, S.E. II

    1982-07-01

    This report describes bench-scale studies on the utilization of microbial cells for the concentration and removal of uranium, radium, and cesium from nuclear processing waste streams. Included are studies aimed at elucidating the basic mechanism of uranium uptake, process development efforts for the use of a combined denitrification-uranium removal process to treat a specific nuclear processing waste stream, and a preliminary investigation of the applicability of microorganisms for the removal of /sup 137/Cs and /sup 226/Ra from existing waste solutions.

  13. Molecular indicators of Nitrobacter spp. population and growth activity during an induced inhibition event in a bench scale nitrification reactor.

    Science.gov (United States)

    Hawkins, Shawn; Robinson, Kevin; Layton, Alice; Sayler, Gary

    2012-04-15

    The Nitrobacter spp. ribosomal RNA gene (rDNA) and transcript (rRNAt) abundance were quantified in a bench scale nitrification reactor during baseline periods of high nitrification efficiency and an intervening staged inhibition event. The transcript to gene ratio (rRNAt/rDNA) was highly sensitive to changes in the reactor nitrite oxidation rate. During high nitrification efficiency, the rRNAt/rDNA metric displayed a range from 0.68 to 2.01 with one-sided (α=0.10) lower and upper prediction intervals of 0.70 and 1.78, respectively. When nitrification was inhibited by disabling the reactor pH control system, this activity metric declined an order of magnitude to ≈ 0.05, well below the lower prediction interval reflecting high nitrification efficiency. The decline was rapid (2h) and preceded a significant drop in reactor nitrification performance, which occurred as ammonia accumulated. The rRNAt/rDNA ratio remained low (≈ 0.05) for several days after the pH control system was re-enabled at a setpoint of 8.0, which otherwise induced rapid oxidation of accumulated ammonia and produced high free ammonia concentrations. The timing of a subsequent increase in the rRNAt/rDNA ratio, which transiently exceeded the upper prediction interval established during the baseline period of high nitrification efficiency, was not coincidental with resumption of pH control at 7.2 that lowered free ammonia concentrations to non-inhibitory levels. Rather, nitrite oxidation resumed and the rRNAt/rDNA ratio increased only after oxidation of accumulated ammonia was complete, which was coincidental with reduced reactor oxygen demand. In summary, the Nitrobacter rRNAt/rDNA activity metric reflected timely and easily recognizable changes in nitrite oxidation activity, illustrating that molecular data can be used to diagnose poor biological wastewater treatment performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Design of Bench-Scale Silicone Process for Low-Cost CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Benjamin

    2012-06-30

    The major goal of the project is to design and optimize a bench-scale process for novel silicone CO{sub 2}-capture solvents and establish scalability and potential for commercialization of post-combustion capture of CO{sub 2} from coal-fired power plants. This system should be capable of 90% capture efficiency and demonstrate that less than 35% increase in the cost of energy services can be achieved upon scale-up. Experiments were conducted to obtain data required for design of the major unit operations. The bench-scale system design has been completed, including sizing of major unit operations and the development of a detailed Process and Instrument Diagram (P&ID). The system has been designed to be able to operate over a wide range of process conditions so that the effect of various process variables on performance can be determined. To facilitate flexibility in operation, the absorption column has been designed in a modular manner, so that the height of the column can be varied. The desorber has also been designed to allow for a range of residence times, temperatures, and pressures. The system will be fabricated at Techniserv Inc.

  15. Bench-Scale Silicone Process for Low-Cost CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Benjamin; Genovese, Sarah; Perry, Robert; Spiry, Irina; Farnum, Rachael; Sing, Surinder; Wilson, Paul; Buckley, Paul; Acharya, Harish; Chen, Wei; McDermott, John; Vipperia, Ravikumar; Yee, Michael; Steele, Ray; Fresia, Megan; Vogt, Kirk

    2013-12-31

    A bench-scale system was designed and built to test an aminosilicone-based solvent. A model was built of the bench-scale system and this model was scaled up to model the performance of a carbon capture unit, using aminosilicones, for CO{sub 2} capture and sequestration (CCS) for a pulverized coal (PC) boiler at 550 MW. System and economic analysis for the carbon capture unit demonstrates that the aminosilicone solvent has significant advantages relative to a monoethanol amine (MEA)-based system. The CCS energy penalty for MEA is 35.9% and the energy penalty for aminosilicone solvent is 30.4% using a steam temperature of 395 °C (743 °F). If the steam temperature is lowered to 204 °C (400 °F), the energy penalty for the aminosilicone solvent is reduced to 29%. The increase in cost of electricity (COE) over the non-capture case for MEA is ~109% and increase in COE for aminosilicone solvent is ~98 to 103% depending on the solvent cost at a steam temperature of 395 °C (743 °F). If the steam temperature is lowered to 204 °C (400 °F), the increase in COE for the aminosilicone solvent is reduced to ~95-100%.

  16. Rate and extent NOM removal during oxidation and biofiltration.

    Science.gov (United States)

    Black, Kerry E; Bérubé, Pierre R

    2014-04-01

    The presence of natural organic matter (NOM) in drinking water treatment presents many challenges. Integrated treatment processes combining oxidation and biofiltration have been demonstrated to be very effective at reducing NOM, specifically biodegradable organics. Laboratory bench-scale experiments were carried out to investigate the effect of oxidation by ozonation or UV/H2O2 on NOM. Specifically the rate of biodegradation was studied by performing bench-scale biodegradation experiments using acclimatized biological activated carbon (BAC). For the source water investigated, oxidation did not preferentially react with the biodegradable or non-biodegradable NOM. In addition, the type or dose of oxidation applied did not affect the observed rate of biodegradation. The rate kinetics for biodegradation were constant for all oxidation conditions investigated. Oxidation prior to biofiltration increased the overall removal of organic matter, but did not affect the rate of biodegradation of NOM. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Bench Scale Development and Testing of Aerogel Sorbents for CO2 Capture Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Begag, Redouane [Aspen Aerogels, Northborough, MA (United States)

    2017-03-30

    The primary objective of this project was scaling up and evaluating a novel Amine Functionalized Aerogel (AFA) sorbent in a bench scale fluidized bed reactor. The project team (Aspen Aerogels, University of Akron, ADA-ES, and Longtail Consulting) has carried out numerous tests and optimization studies to demonstrate the CO2 capture performance of the AFA sorbent in all its forms: powder, pellet, and bead. The CO2 capture target performance of the AFA sorbent (all forms) were set at > 12 wt.% and > 6 wt.% for total and working CO2 capacity, respectively (@ 40 °C adsorption / 100 – 120 °C desorption). The optimized AFA powders outperformed the performance targets by more than 30%, for the total CO2 capacity (14 - 20 wt.%), and an average of 10 % more for working CO2 capacity (6.6 – 7.0 wt.%, and could be as high as 9.6 wt. % when desorbed at 120 °C). The University of Akron developed binder formulations, pellet production methods, and post treatment technology for increased resistance to attrition and flue gas contaminants. In pellet form the AFA total CO2 capacity was ~ 12 wt.% (over 85% capacity retention of that of the powder), and there was less than 13% degradation in CO2 capture capacity after 20 cycles in the presence of 40 ppm SO2. ADA-ES assessed the performance of the AFA powder, pellet, and bead by analyzing sorption isotherms, water uptake analysis, cycling stability, jet cup attrition and crush tests. At bench scale, the hydrodynamic and heat transfer properties of the AFA sorbent pellet in fluidized bed conditions were evaluated at Particulate Solid Research, Inc. (PSRI). After the process design requirements were completed, by Longtail Consulting LLC, a techno-economic analysis was achieved using guidance from The National Energy Technology Laboratory (NETL) report. This report provides the necessary framework to estimate costs for a temperature swing post

  18. Treatment of pulp mill sludges by supercritical water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Modell, M.

    1990-07-01

    Supercritical water oxidation (SCWO) is new process that can oxidize organics very effectively at moderate temperatures (400 to 650{degree}C) and high pressure (3700 psi). It is an environmentally acceptable alternative for sludge treatment. In bench scale tests, total organic carbon (TOC) and total organic halide (TOX) reductions of 99 to 99.9% were obtained; dioxin reductions were 95 to 99.9%. A conceptual design for commercial systems has been completed and preliminary economics have been estimated. Comparisons confirm that SCWO is less costly than dewatering plus incineration for treating pulp mill sludges. SCWO can also compete effectively with dewatering plus landfilling where tipping fees exceed $35/yd{sup 3}. In some regions of the US, tipping fees are now $75/yd{sup 3} and rising steadily. In the 1995 to 2000 time frame, SCWO has a good chance of becoming the method of choice. MODEC's objective is to bring the technology to commercial availability by 1993. 10 refs., 6 figs., 19 tabs.

  19. Residual moisture reduction of coarse coal using air purging. 1. Bench scale studies

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, B.K.; Nicol, S.K.; Veal, C.J. [CSIRO, North Ryde, NSW (Australia). Division of Energy Technology

    2001-02-01

    Air purging is a new way of reducing the moisture content of coarse coal product from vibrating basket centrifuges. The process concept involves the injection of a turbulent stream of high velocity air through the coal bed as it traverses the centrifuge basket. This paper describes some of the basic work that was undertaken to establish the feasibility of this approach, including bench-scale experiments. Tests in a purpose-designed batch centrifuge basket, in which the sample was spun and purged at the same time, showed that air purging was effective on a rank range of coals, the higher rank coals responding the best. Under these idealised conditions, substantial moisture reductions of between 1.5 and2.7 wt% were achieved. 11 refs., 10 figs., 1 tab.

  20. Bench-scale testing of a micronized magnetite, fine-coal cleaning process

    Energy Technology Data Exchange (ETDEWEB)

    Suardini, P.J. [Custom Coals, International, Pittsburgh, PA (United States)

    1995-11-01

    Custom Coals, International has installed and is presently testing a 500 lb/hr. micronized-magnetite, fine-coal cleaning circuit at PETC`s Process Research Facility (PRF). The cost-shared project was awarded as part of the Coal Preparation Program`s, High Efficiency Preparation Subprogram. The project includes design, construction, testing, and decommissioning of a fully-integrated, bench-scale circuit, complete with feed coal classification to remove the minus 30 micron slimes, dense medium cycloning of the 300 by 30 micron feed coal using a nominal minus 10 micron size magnetite medium, and medium recovery using drain and rinse screens and various stages and types of magnetic separators. This paper describes the project circuit and goals, including a description of the current project status and the sources of coal and magnetite which are being tested.

  1. Bench scale testing of micronized magnetite beneficiation. Quarterly technical progress report 4, October--December, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Anast, K.

    1994-01-25

    This project is aimed at development of a process that, by using ultra fine magnetite suspension, would expand the application of heavy media separation technology to processing fine, {minus}28 mesh coals. These coal fines, produced during coal mining and crushing, are separated in the conventional coal preparation plant and generally impounded in a tailings pond. Development of an economic process for processing these fines into marketable product will expand the utilization of coal for power production in an environmentally acceptable and economically viable way. This process has been successfully researched at PETC but has not been studied on a continuous bench-scale unit, which is a necessary step towards commercial development of this promising technology. The goal of the program is to investigate the technology in a continuous circuit at a reasonable scale to provide a design basis for larger plants and a commercial feasibility data.

  2. Bench-scale treatability testing of biological, UV oxidation, distillation, and ion-exchange treatment of trench water from a low-level radioactive waste disposal area at West Valley, New York

    Energy Technology Data Exchange (ETDEWEB)

    Sundquist, J.A.; Gillings, J.C. [Ecology and Environment, Inc. (United States); Sonntag, T.L. [New York State Energy Research and Development Authority (United States); Denault, R.P. [Pacific Nuclear, Inc. (United States)

    1993-03-01

    Ecology and Environment, Inc. (E and E), under subcontract to Pacific Nuclear Services (PNS), conducted for the New York State Energy Research and Development Authority (NYSERDA) treatability tests to support the selection and design of a treatment system for leachate from Trench 14 of the West Valley State-Licensed, Low-Level Radioactive Waste Disposal Area (SDA). In this paper E and E presents and discusses the treatability test results and provides recommendations for the design of the full-scale treatment system.

  3. Bench-scale screening tests for a boiling sodium-potassium alloy solar receiver

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.B.; Moss, T.A.

    1993-06-01

    Bench-scale tests were carried out in support of the design of a second-generation 75-kW{sub t} reflux pool-boiler solar receiver. The receiver will be made from Haynes Alloy 230 and will contain the sodium-potassium alloy NaK-78. The bench-scale tests used quartz-lamp-heated boilers to screen candidate boiling-stabilization materials and methods at temperatures up to 750{degree}C. Candidates that provided stable boiling were tested for hot-restart behavior. Poor stability was obtained with single 1/4-inch diameter patches of powdered metal hot-press-sintered onto the wetted side of the heat-input area. Laser-drilled and electric-discharge-machined cavities in the heated surface also performed poorly. Small additions of xenon, and heated-surface tilt out of the vertical dramatically improved poor boiling stability; additions of helium or oxygen did not. The most stable boiling was obtained when the entire heat-input area was covered by a powdered-metal coating. The effect of heated-area size was assessed for one coating: at low incident fluxes, when even this coating performed poorly, increasing the heated-area size markedly improved boiling stability. Good hot-restart behavior was not observed with any candidate, although results were significantly better with added xenon in a boiler shortened from 3 to 2 feet. In addition to the screening tests, flash-radiography imaging of metal-vapor bubbles during boiling was attempted. Contrary to the Cole-Rohsenow correlation, these bubble-size estimates did not vary with pressure; instead they were constant, consistent with the only other alkali metal measurements, but about 1/2 their size.

  4. A bench-scale study on the removal and recovery of phosphate by hydrous zirconia-coated magnetite nanoparticles

    Science.gov (United States)

    Wang, Zhe; Fang, Wenkan; Xing, Mingchao; Wu, Deyi

    2017-02-01

    Owing to the easy magnetic separation from water for reuse, magnetic nanoparticles have drawn great interest as adsorbents. Herein hydrous zirconia-coated magnetite nanoparticles (Fe3O4@ZrO2) were created by a facile method and a bench-scale study was undertaken to evaluate its effectiveness and mechanism to remove phosphate at low concentrations. Results indicated that phosphate removal by Fe3O4@ZrO2 was fast (95% of phosphate removal within 10 min) and nearly complete removal could be achieved at the adsorbent dosage >0.6 g/L. In tap water or wastewater where competitive anions coexist, regulation of pH was found to be quite effective to augment the performance of phosphate removal. In pH-lowered adsorption systems, phosphate removal followed a good pattern similarly to pure water, i.e., a continuous high efficiency removal followed by a rapid saturation. Adsorption-desorption-regeneration studies showed that Fe3O4@ZrO2 could be repeatedly used for phosphate removal and adsorbed phosphate could be stripped for recovery. The fractionation of adsorbed phosphorus suggested that NaOH-P fraction was dominant. We also found that the adsorption reaction of phosphate with Fe3O4@ZrO2 shifted the isoelectric point of Fe3O4@ZrO2 from 9.0 to 3.0. FTIR measurements further showed the direct coordination of phosphate onto zirconium by replacement of hydroxyl groups. The formation of the monodentate (ZrO)PO2(OH) complex was proposed.

  5. Bench-Scale Monolith Autothermal Reformer Catalyst Screening Evaluations in a Micro-Reactor With Jet-A Fuel

    Science.gov (United States)

    Tomsik, Thomas M.; Yen, Judy C.H.; Budge, John R.

    2006-01-01

    Solid oxide fuel cell systems used in the aerospace or commercial aviation environment require a compact, light-weight and highly durable catalytic fuel processor. The fuel processing method considered here is an autothermal reforming (ATR) step. The ATR converts Jet-A fuel by a reaction with steam and air forming hydrogen (H2) and carbon monoxide (CO) to be used for production of electrical power in the fuel cell. This paper addresses the first phase of an experimental catalyst screening study, looking at the relative effectiveness of several monolith catalyst types when operating with untreated Jet-A fuel. Six monolith catalyst materials were selected for preliminary evaluation and experimental bench-scale screening in a small 0.05 kWe micro-reactor test apparatus. These tests were conducted to assess relative catalyst performance under atmospheric pressure ATR conditions and processing Jet-A fuel at a steam-to-carbon ratio of 3.5, a value higher than anticipated to be run in an optimized system. The average reformer efficiencies for the six catalysts tested ranged from 75 to 83 percent at a constant gas-hourly space velocity of 12,000 hr 1. The corresponding hydrocarbon conversion efficiency varied from 86 to 95 percent during experiments run at reaction temperatures between 750 to 830 C. Based on the results of the short-duration 100 hr tests reported herein, two of the highest performing catalysts were selected for further evaluation in a follow-on 1000 hr life durability study in Phase II.

  6. Bench scale steam explosion pretreatment of acid impregnated elephant grass biomass and its impacts on biomass composition, structure and hydrolysis

    NARCIS (Netherlands)

    Kataria, Rashmi; Mol, Annemerel; Schulten, Els; Happel, Anton; Mussatto, Solange I.

    2017-01-01

    In the present study, an acid mediated steam explosion process was evaluated for pretreatment of elephant grass biomass in a bench scale reactor. Different combinations of H2SO4 concentration, reaction time and temperature (leading to different values of combined severity factor - CSF) were used for

  7. A novel bench-scale column assay to investigate site-specific nitrification biokinetics in biological rapid sand filters

    DEFF Research Database (Denmark)

    Tatari, Karolina; Smets, Barth F.; Albrechtsen, Hans-Jørgen

    2013-01-01

    A bench-scale assay was developed to obtain site-specific nitrification biokinetic information from biological rapid sand filters employed in groundwater treatment. The experimental set-up uses granular material subsampled from a full-scale filter, packed in a column, and operated with controlled...

  8. Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high temperature pyrolysis.

    NARCIS (Netherlands)

    Westerhout, R.W.J.; Westerhout, R.W.J.; Waanders, J.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1998-01-01

    The high-temperature pyrolysis of polyethene (PE), polypropene (PP), and mixtures of these polymers was studied in a novel bench-scale rotating cone reactor (RCR). Experiments showed that the effect of the sand or reactor temperature on the product spectrum obtained is large compared to the effect

  9. Pyrolysis of automotive shredder residue in a bench scale rotary kiln.

    Science.gov (United States)

    Notarnicola, Michele; Cornacchia, Giacinto; De Gisi, Sabino; Di Canio, Francesco; Freda, Cesare; Garzone, Pietro; Martino, Maria; Valerio, Vito; Villone, Antonio

    2017-07-01

    Automotive shredder residue (ASR) can create difficulties when managing, with its production increasing. It is made of different type of plastics, foams, elastomers, wood, glasses and textiles. For this reason, it is complicated to dispose of in a cost effective way, while also respecting the stringent environmental restrictions. Among thermal treatments, pyrolysis seems to offer an environmentally attractive method for the treatment of ASR; it also allows for the recovery of valuable secondary materials/fuels such as pyrolysis oils, chars, and gas. While, there is a great deal of significant research on ASR pyrolysis, the literature on higher scale pyrolysis experiments is limited. To improve current literature, the aim of the study was to investigate the pyrolysis of ASR in a bench scale rotary kiln. The Italian ASR was separated by dry-sieving into two particle size fractions: d30mm. Both the streams were grounded, pelletized and then pyrolyzed in a continuous bench scale rotary kiln at 450, 550 and 650°C. The mass flow rate of the ASR pellets was 200-350g/h and each test ran for about 4-5h. The produced char, pyrolysis oil and syngas were quantified to determine product distribution. They were thoroughly analyzed with regard to their chemical and physical properties. The results show how higher temperatures increase the pyrolysis gas yield (44wt% at 650°C) as well as its heating value. The low heating value (LHV) of syngas ranges between 18 and 26MJ/Nm 3 dry. The highest pyrolysis oil yield (33wt.%) was observed at 550°C and its LHV ranges between 12.5 and 14.5MJ/kg. Furthermore, only two out of the six produced chars respect the LHV limit set by the Italian environmental regulations for landfilling. The obtained results in terms of product distribution and their chemical-physical analyses provide useful information for plant scale-up. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Hierarchical calibration and validation for modeling bench-scale solvent-based carbon capture. Part 1: Non-reactive physical mass transfer across the wetted wall column: Original Research Article: Hierarchical calibration and validation for modeling bench-scale solvent-based carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA; Xu, Zhijie [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA; Lai, Canhai [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA; Whyatt, Greg [Pacific Northwest National Laboratory, Energy and Environment Directorate, Richland WA; Marcy, Peter [Statistical Sciences Group, Los Alamos National Laboratory, Los Alamos NM; Sun, Xin [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA

    2017-04-27

    A hierarchical model calibration and validation is proposed for quantifying the confidence level of mass transfer prediction using a computational fluid dynamics (CFD) model, where the solvent-based carbon dioxide (CO2) capture is simulated and simulation results are compared to the parallel bench-scale experimental data. Two unit problems with increasing level of complexity are proposed to breakdown the complex physical/chemical processes of solvent-based CO2 capture into relatively simpler problems to separate the effects of physical transport and chemical reaction. This paper focuses on the calibration and validation of the first unit problem, i.e. the CO2 mass transfer across a falling ethanolamine (MEA) film in absence of chemical reaction. This problem is investigated both experimentally and numerically using nitrous oxide (N2O) as a surrogate for CO2. To capture the motion of gas-liquid interface, a volume of fluid method is employed together with a one-fluid formulation to compute the mass transfer between the two phases. Bench-scale parallel experiments are designed and conducted to validate and calibrate the CFD models using a general Bayesian calibration. Two important transport parameters, e.g. Henry’s constant and gas diffusivity, are calibrated to produce the posterior distributions, which will be used as the input for the second unit problem to address the chemical adsorption of CO2 across the MEA falling film, where both mass transfer and chemical reaction are involved.

  11. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Ciliberti, D.F.; Lippert, T.E.

    1985-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  12. 100 Area soil washing: Bench scale tests on 116-F-4 pluto crib soil

    Energy Technology Data Exchange (ETDEWEB)

    Field, J.G.

    1994-06-10

    The Pacific Northwest Laboratory conducted a bench-scale treatability study on a pluto crib soil sample from 100 Area of the Hanford Site. The objective of this study was to evaluate the use of physical separation (wet sieving), treatment processes (attrition scrubbing, and autogenous surface grinding), and chemical extraction methods as a means of separating radioactively-contaminated soil fractions from uncontaminated soil fractions. The soil washing treatability study was conducted on a soil sample from the 116-F-4 Pluto Crib that had been dug up as part of an excavation treatability study. Trace element analyses of this soil showed no elevated concentrations above typically uncontaminated soil background levels. Data on the distribution of radionuclide in various size fractions indicated that the soil-washing tests should be focused on the gravel and sand fractions of the 116-F-4 soil. The radionuclide data also showed that {sup 137}Cs was the only contaminant in this soil that exceeded the test performance goal (TPG). Therefore, the effectiveness of subsequent soil-washing tests for 116-F-4 soil was evaluated on the basis of activity attenuation of {sup 137}Cs in the gravel- and sand-size fractions.

  13. Optimal sludge retention time for a bench scale MBR treating municipal sewage.

    Science.gov (United States)

    Pollice, A; Laera, G; Saturno, D; Giordano, C; Sandulli, R

    2008-01-01

    Membrane bioreactors allow for higher sludge concentrations and improved degradation efficiencies with respect to conventional activated sludge. However, in the current practice these systems are often operated under sub-optimal conditions, since so far no precise indications have yet been issued on the optimal operating conditions of MBR for municipal wastewater treatment. This paper reports some results of four years of operation of a bench scale membrane bioreactor where steady state conditions were investigated under different sludge retention times. The whole experimental campaign was oriented towards the investigation of optimal process conditions in terms of COD removal and nitrification, biomass activity and growth, and sludge characteristics. The membrane bioreactor treated real municipal sewage, and four different sludge ages were tested (20, 40, 60, and 80 days) and compared with previous data on complete sludge retention. The results showed that the the biology of the system, as assessed by the oxygen uptake rate, is less affected than the sludge physical parameters. In particular, although the growth yield was observed to dramatically drop for SRT higher than 80 days, the biological activity was maintained under all the tested conditions. These considerations suggest that high SRT are convenient in terms of limited excess sludge production without losses of the treatment capacity. Physical characteristics such as the viscosity and the filterability appear to be negatively affected by prolonged sludge retention times, but their values remain within the ranges normally reported for conventional activated sludge.

  14. Numerical simulation of competitive aerobic / anaerobic hydrocarbon plume biodegradation in two-dimensional bench scale lab-experiments

    Science.gov (United States)

    Beyer, C.; Ballarini, E.; Bauer, R.; Griebler, C.; Bauer, S.

    2011-12-01

    The biodegradation of oxidizable hydrocarbon contaminants in the subsurface requires the presence of compatible microbial communities as well as sufficient amounts of electron acceptors and nutrients. In this context, transverse mixing, driven by dispersion and diffusion, is one of the main mechanisms governing the availability of dissolved electron acceptors at a hydrocarbon plume fringe. Aerobic and anaerobic biodegradation of hydrocarbons limited by transverse mixing has been studied experimentally in 2D bench-scale flow-through tanks, filled with a saturated porous medium. Flow of groundwater through the tanks was induced by pumping water at one side through injection ports, and simultaneously extracting water at the other side of the tank. An ethylbenzene plume was established by injection through the central inlet port. A mixture of unlabeled and fully deuterium-labeled isotopomers was used in order to investigate the spatial distribution of degradation processes via monitoring of compound-specific stable isotope fractionation. In the first phase of the experiment, aerobic biodegradation was studied. For this purpose, the tank was recharged with water containing oxygen as a dissolved electron acceptor and the aerobic strain Pseudomonas putida F1 was inoculated. Later, nitrate was added to the recharge water as an additional electron acceptor and the denitrifying strain Aromatoleum aromaticum EbN1 was amended to study competitive aerobic/anaerobic biodegradation. A numerical reactive transport model of the experiment was set up for a model based interpretation of the observed degradation patterns. In a sensitivity analysis, the influence of the relevant hydrodynamic parameters on the observable distributions of ethylbenzene isotopomers, oxygen and nitrate was studied. Subsequent model calibration allowed for a good agreement with ethylbenzene concentrations measured at the tank outlet ports as well as oxygen concentrations, which were measured at several

  15. Bench-scale experimental determination of the thermal diffusivity of crushed tuff

    Energy Technology Data Exchange (ETDEWEB)

    Ryder, E.E.; Finley, R.E.; George, J.T.; Ho, C.K.; Longenbaugh, R.S. [Sandia National Labs., Albuquerque, NM (United States); Connolly, J.R. [New Mexico Univ., Albuquerque, NM (United States)

    1996-06-01

    A bench-scale experiment was designed and constructed to determine the effective thermal diffusivity of crushed tuff. Crushed tuff particles ranging from 12.5 mm to 37.5 mm (0.5 in. to 1.5 in.) were used to fill a cylindrical volume of 1.58 m{sup 3} at an effective porosity of 0.48. Two iterations of the experiment were completed; the first spanning approximately 502 hours and the second 237 hours. Temperatures near the axial heater reached 700 degrees C, with a significant volume of the test bed exceeding 100 degrees C. Three post-test analysis techniques were used to estimate the thermal diffusivity of the crushed tuff. The first approach used nonlinear parameter estimation linked to a one dimensional radial conduction model to estimate thermal diffusivity from the first 6 hours of test data. The second method used the multiphase TOUGH2 code in conjunction with the first 20 hours of test data not only to estimate the crushed tuffs thermal diffusivity, but also to explore convective behavior within the test bed. Finally, the nonlinear conduction code COYOTE-II was used to determine thermal properties based on 111 hours of cool-down data. The post-test thermal diffusivity estimates of 5.0 x 10-7 m{sup 2}/s to 6.6 x 10-7 m{sup 2}/s were converted to effective thermal conductivities and compared to estimates obtained from published porosity-based relationships. No obvious match between the experimental data and published relationships was found to exist; however, additional data for other particle sizes and porosities are needed.

  16. Bench-Scale Silicone Process for Low-Cost CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Fresia, Megan; Vogt, Kirk

    2013-12-31

    GE Global Research is developing technology to remove carbon dioxide (CO{sub 2}) from the flue gas of coal-fired power plants. A mixture of 3-aminopropyl end-capped polydimethylsiloxane (GAP-1m) and triethylene glycol (TEG) is the preferred CO{sub 2} capture solvent. GE Global Research was contracted by the Department of Energy to test a bench-scale continuous CO{sub 2} absorption/desorption system using a GAP-1m/TEG mixture as the solvent. SiVance LLC was sub-contracted to provide the GAP-1m material and conduct an Environmental, Health, and Safety (EH&S) assessment for a 550 MW coal-fired power plant. Five components of the solvent, CAS#2469-55-8 (GAP-0), CAS#106214-84-0 (GAP-1-4), TEG, and methanol and xylene (minor contaminants from the aminosilicone) are included in this assessment. One by-product, GAP-1m/SOX salt, and dodecylbenzenesulfonic acid (DDBSA) were also identified for analysis. All of the solvent components and DDBSA are listed on the EPA’s TSCA Inventory allowing companies to manufacture and use the chemicals commercially. The toxicological effects of each component were defined, and control mechanisms necessary to comply with U.S. EH&S regulations are summarized. An engineering and control system, including environmental abatement, was described for minimizing exposure and release of the chemical components. Proper handling and storage recommendations are made for each chemical to minimize risk to workers and the surrounding community.

  17. Bench-scale recovery of phosphorus from flushed dairy manure wastewater.

    Science.gov (United States)

    Harris, Willie G; Wilkie, Ann C; Cao, Xinde; Sirengo, Roy

    2008-05-01

    Recovery of phosphorus (P) from flushed dairy manure in an easily-dewatered form would enable farmers to manage P as a resource rather than land-apply it in excess at environmental risk. The purpose of this study was to evaluate (i) the feasibility of P recovery and (ii) the form of recovered P from flushed dairy manure wastewater using crystallization in a fluidized-bed reactor. Wastewater was pumped directly from a dairy farm reservoir and continuously fed in parallel through four bench-scale fluidized-bed reactors deployed on-site. Chemical additives (NaOH and MgSO4) required for recovery were injected directly into the zone of fluidization. Recovered P forms were assessed by X-ray diffraction, scanning electron microscopy, and micro-elemental analysis. Recovery of P as poorly-crystalline hydroxylapatite (HAP) was documented in coatings ultrasonically removed from quartz seed grains following fluidization at elevated pH in conjunction with MgSO4 injection. Addition of MgSO4 was required to prevent CaCO3 precipitation upon pH elevation and hence enable calcium phosphate precipitation. It is likely that MgSO4 inhibited CaCO3 via formation of MgCO3 (aq). Periclase (MgO), which also served as an effective seed material, generated sufficient alkalinity at grain surfaces to precipitate abundant CaCO3 and in some cases detectable Ca phosphate even without NaOH addition to elevate pH of bulk solution.

  18. Results of bench-scale plasma system testing in support of the Plasma Hearth Process

    Energy Technology Data Exchange (ETDEWEB)

    Leatherman, G.L.; Cornelison, C. [Science Applications International Corp., Idaho Falls, ID (United States); Frank, S. [Argonne National Lab., Idaho Falls, ID (United States)

    1996-10-01

    The Plasma Hearth Process (PHP) is a high-temperature process that destroys hazardous organic components and stabilizes the radioactive components and hazardous metals in a leach-resistant vitreous slag waste form. The PHP technology development program is targeted at mixed waste that cannot be easily treated by conventional means. For example, heterogeneous debris, which may contain hazardous organics, toxic metals, and radionuclides, is difficult to characterize and cannot be treated with conventional thermal, chemical, or physical treatment methods. A major advantage of the PHP over other plasma processes is its ability to separate nonradioactive, non-hazardous metals from the non-metallic and radioactive components which are contained in the vitreous slag. The overall PHP program involves the design, fabrication, and operation of test hardware to demonstrate and certify that the PHP concept is viable for DOE waste treatment. The program involves bench-scale testing of PHP equipment in radioactive service, as well as pilot-scale demonstration of the PHP concept using nonradioactive, surrogate test materials. The fate of secondary waste streams is an important consideration for any technology considered for processing mixed waste. The main secondary waste stream generated by the PHP is flyash captured by the fabric- filter baghouse. The PHP concept is that flyash generated by the process can, to a large extent, be treated by processing this secondary waste stream in the PHP. Prior to the work presented in the paper, however, the PHP project has not quantitatively demonstrated the ability to treat PHP generated flyash. A major consideration is the quantity of radionuclides and RCRA-regulated metals in the flyash that can be retained the resultant waste form.

  19. Catalytic water oxidation: Rugged water-oxidation anodes

    Science.gov (United States)

    Llobet, Antoni

    2010-10-01

    The efficient catalytic oxidation of water to dioxygen in the solid state is one of the challenges to be overcome to build sun-driven and/or electrocatalytic water-splitting devices. Now, an effective water-oxidation hybrid catalyst system has been made by attaching a ruthenium-polyoxometallate complex to a carbon nanotube.

  20. Permeable Reactive Biobarriers for In Situ Cr(VI) Reduction: Bench Scale Tests Using Cellulomonas sp. Strain ES6

    Energy Technology Data Exchange (ETDEWEB)

    Sridhar Viamajala; Brent M. Peyton; Robin Gerlach; Vaideeswaran; William A. Apel; James N. Petersen

    2008-12-01

    Chromate (Cr(VI)) reduction studies were performed in bench scale flow columns using the fermentative subsurface isolate Cellulomonas sp. strain ES6. In these tests, columns packed with either quartz sand or hydrous ferric oxide (HFO)-coated quartz sand, were inoculated with strain ES6 and fed nutrients to stimulate growth before nutrient-free Cr(VI) solutions were injected. Results show that in columns containing quartz sand, a continuous inflow of 2 mg/L Cr(VI) was reduced to below detection limits in the effluent for durations of up to 5.7 residence times after nutrient injection was discontinued proving the ability of strain ES6 to reduce chromate in the absence of an external electron donor. In the HFO-containing columns, Cr(VI) reduction was significantly prolonged and effluent Cr(VI) concentrations remained below detectable levels for periods of up to 66 residence times after nutrient injection was discontinued. Fe was detected in the effluent of the HFO-containing columns throughout the period of Cr(VI) removal indicating that the insoluble Fe(III) bearing solids were being continuously reduced to form soluble Fe(II) resulting in prolonged abiotic Cr(VI) reduction. Thus, growth of Cellulomonas within the soil columns resulted in formation of permeable reactive barriers that could reduce Cr(VI) and Fe(III) for extended periods even in the absence of external electron donors. Other bioremediation systems employing Fe(II)-mediated reactions require a continuous presence of external nutrients to regenerate Fe(II). After depletion of nutrients, contaminant removal within these systems occurs by reaction with surface-associated Fe(II) that can rapidly become inaccessible due to formation of crystalline Fe-minerals or other precipitates. The ability of fermentative organisms like Cellulomonas to reduce metals without continuous nutrient supply in the subsurface offers a viable and economical alternative technology for in situ remediation of Cr

  1. Permeable reactive biobarriers for in situ Cr(VI) reduction: bench scale tests using Cellulomonas sp. strain ES6.

    Science.gov (United States)

    Viamajala, Sridhar; Peyton, Brent M; Gerlach, Robin; Sivaswamy, Vaideeswaran; Apel, William A; Petersen, James N

    2008-12-15

    Chromate (Cr(VI)) reduction studies were performed in bench scale flow columns using the fermentative subsurface isolate Cellulomonas sp. strain ES6. In these tests, columns packed with either quartz sand or hydrous ferric oxide (HFO)-coated quartz sand, were inoculated with strain ES6 and fed nutrients to stimulate growth before nutrient-free Cr(VI) solutions were injected. Results show that in columns containing quartz sand, a continuous inflow of 2 mg/L Cr(VI) was reduced to below detection limits in the effluent for durations of up to 5.7 residence times after nutrient injection was discontinued proving the ability of strain ES6 to reduce chromate in the absence of an external electron donor. In the HFO-containing columns, Cr(VI) reduction was significantly prolonged and effluent Cr(VI) concentrations remained below detectable levels for periods of up to 66 residence times after nutrient injection was discontinued. Fe was detected in the effluent of the HFO-containing columns throughout the period of Cr(VI) removal indicating that the insoluble Fe(III) bearing solids were being continuously reduced to form soluble Fe(II) resulting in prolonged abiotic Cr(VI) reduction. Thus, growth of Cellulomonas within the soil columns resulted in formation of permeable reactive barriers that could reduce Cr(VI) and Fe(III) for extended periods even in the absence of external electron donors. Other bioremediation systems employing Fe(II)-mediated reactions require a continuous presence of external nutrients to regenerate Fe(II). After depletion of nutrients, contaminant removal within these systems occurs by reaction with surface-associated Fe(II) that can rapidly become inaccessible due to formation of crystalline Fe-minerals or other precipitates. The ability of fermentative organisms like Cellulomonas to reduce metals without continuous nutrient supply in the subsurface offers a viable and economical alternative technology for in situ remediation of Cr

  2. Enhanced removal of VOCs from aquifers during air sparging using thickeners and surfactants: Bench-scale experiments.

    Science.gov (United States)

    Kim, Heonki; Ahn, Dayoung; Annable, Michael D

    2016-01-01

    The effects of controlled air flow paths during air sparging on the removal of volatile organic compounds were examined in this study using a two-dimensional bench-scale physical model. An aqueous solution of sodium carboxymethylcellulose (SCMC), which is a thickener, was used to increase the resistance of water to displacement by injected air in a region around the targeted zone. At the same time, an aqueous solution of sodium dodecylbenzene sulfonate (SDBS), which is a surfactant, was used to reduce the air entry pressure to enhance the air flow through the targeted region. Trichloroethene (TCE), dissolved in water, was used to represent an aqueous phase volatile organic compound (VOC). A binary mixture of perchloroethene (PCE) and n-hexane was also used as a nonaqeous phase liquid (NAPL). Controlled air flow through the source zone, achieved by emplacing a high viscosity aqueous solution into a region surrounding the TCE-impacted zone, resulted in increased TCE removal from 23.0% (control) to 38.2% during a 2.5h period. When the air flow was focused on the targeted source zone of aqueous phase TCE (by decreasing the surface tension within the source zone and its vicinity by 28 dyn/cm, no SCMC applied), the mass removal of TCE was enhanced to 41.3% during the same time period. With SCMC and SDBS applied simultaneously around and beneath a NAPL source zone, respectively, the NAPL components were found to be removed more effectively over a period of 8.2h than the sparging experiment with no additives applied; 84.6% of PCE and 94.0% of n-hexane were removed for the controlled air flow path experiments (with both SCMC and SDBS applied) compared to 52.7% (PCE) and 74.0% (n-hexane) removal for the control experiment (no additives applied). Based on the experimental observations made in this study, applying a viscous aqueous solution around the source zone and a surfactant solution in and near the source zone, the air flow was focused through the targeted contaminant

  3. Soluble Microbial Product Characterization of Biofilm Formation in Bench-Scale

    KAUST Repository

    Mines, Paul

    2012-12-01

    The biological process known as activated sludge (AS) in conjunction with membrane separation technology for the treatment of wastewater has been employed for over four decades. While, membrane biological reactors (MBR) are now widely employed, the phenomenon of membrane fouling is still the most significant factor leading to performance decline of MBRs. Although much research has been done on the subject of MBR fouling over the past two decades, many questions remain unanswered, and consensus within the scientific community is rare. However, research has led to one system parameter generally being regarded as a contributor to membrane fouling, extracellular polymeric compounds (EPS). EPS, and more specifically, the soluble fraction of EPS known as soluble microbial products (SMP), must be further investigated in order to better understand membrane fouling. The biological activity and performance of the MBR is affected by myriad operational parameters, which in turn affects the SMP generated. A commonly varied operational parameter is, depending on the specific treatment needs of a MBR, the sludge retention time (SRT). This study aims to characterize the SMP in three bench-scale MBRs as the SRT is gradually lowered. By studying how the SMP change as the operation of the system is altered, greater understanding of how SMP are related to fouling can be achieved. At the onset of the study, a steady state was established in the system with a SRT of 20 days. Upon stabilization of a 20 day SRT, the system was gradually transitioned to a five and a half day SRT, in stepwise adjustments. Initially, both the trans-membrane pressure (TMP) and the SMP concentrations were at relatively low values, indicating the presence of minimal amounts of biofilm on the membrane surfaces. As the system was altered and more activated sludge was wasted from the reactors, the SRT inherently decreased. As the lower SRT was transitioned and established, the data from TMP measurements, as well

  4. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  5. Catalytic multi-stage liquefaction of coal at HTI: Bench-scale studies in coal/waste plastics coprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, V.R.; Lee, L.K.; Stalzer, R.H. [Hydrocarbon Technologies, Inc., Lawrenceville, NJ (United States)] [and others

    1995-12-31

    The development of Catalytic Multi-Stage Liquefaction (CMSL) at HTI has focused on both bituminous and sub-bituminous coals using laboratory, bench and PDU scale operations. The crude oil equivalent cost of liquid fuels from coal has been curtailed to about $30 per barrel, thus achieving over 30% reduction in the price that was evaluated for the liquefaction technologies demonstrated in the late seventies and early eighties. Contrary to the common belief, the new generation of catalytic multistage coal liquefaction process is environmentally very benign and can produce clean, premium distillates with a very low (<10ppm) heteroatoms content. The HTI Staff has been involved over the years in process development and has made significant improvements in the CMSL processing of coals. A 24 month program (extended to September 30, 1995) to study novel concepts, using a continuous bench scale Catalytic Multi-Stage unit (30kg coal/day), has been initiated since December, 1992. This program consists of ten bench-scale operations supported by Laboratory Studies, Modelling, Process Simulation and Economic Assessments. The Catalytic Multi-Stage Liquefaction is a continuation of the second generation yields using a low/high temperature approach. This paper covers work performed between October 1994- August 1995, especially results obtained from the microautoclave support activities and the bench-scale operations for runs CMSL-08 and CMSL-09, during which, coal and the plastic components for municipal solid wastes (MSW) such as high density polyethylene (HDPE)m, polypropylene (PP), polystyrene (PS), and polythylene terphthlate (PET) were coprocessed.

  6. Biomimetic Water-Oxidation Catalysts: Manganese Oxides.

    Science.gov (United States)

    Kurz, Philipp

    2016-01-01

    The catalytic oxidation of water to molecular oxygen is a key process for the production of solar fuels. Inspired by the biological manganese-based active site for this reaction in the enzyme Photosystem II, researchers have made impressive progress in the last decades regarding the development of synthetic manganese catalysts for water oxidation. For this, it has been especially fruitful to explore the many different types of known manganese oxides MnOx. This chapter first offers an overview of the structural, thermodynamic, and mechanistic aspects of water-oxidation catalysis by MnOx. The different test systems used for catalytic studies are then presented together with general reactivity trends. As a result, it has been possible to identify layered, mixed Mn (III/IV)-oxides as an especially promising class of bio-inspired catalysts and an attempt is made to give structure-based reasons for the good performances of these materials. In the outlook, the challenges of catalyst screenings (and hence the identification of a "best MnOx catalyst") are discussed. There is a great variety of reaction conditions which might be relevant for the application of manganese oxide catalysts in technological solar fuel-producing devices, and thus catalyst improvements are currently still addressing a very large parameter space. Nonetheless, detailed knowledge about the biological catalyst and a solid experimental basis concerning the syntheses and water-oxidation reactivities of MnOx materials have been established in the last decade and thus this research field is well positioned to make important contributions to solar fuel research in the future.

  7. Hierarchical Calibration and Validation Framework of Bench-scale Computational Fluid Dynamics Simulations for Solvent-based Carbon Capture: Part 2. Chemical Absorption across a Wetted Wall Column

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Xu, Zhijie; Lai, Canhai; Whyatt, Greg A.; Marcy, Peter; Sun, Xin

    2018-02-01

    The first part of this paper (Part 1) presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work has the ability to account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry’s constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.

  8. Bench-Scale Process for Low-Cost Carbon Dioxide (CO2) Capture Using a Phase-Changing Absorbent

    Energy Technology Data Exchange (ETDEWEB)

    Westendorf, Tiffany; Caraher, Joel; Chen, Wei; Farnum, Rachael; Perry, Robert; Spiry, Irina; Wilson, Paul; Wood, Benjamin

    2015-03-31

    The objective of this project is to design and build a bench-scale process for a novel phase-changing aminosilicone-based CO2-capture solvent. The project will establish scalability and technical and economic feasibility of using a phase-changing CO2-capture absorbent for post-combustion capture of CO2 from coal-fired power plants with 90% capture efficiency and 95% CO2 purity at a cost of $40/tonne of CO2 captured by 2025 and a cost of <$10/tonne of CO2 captured by 2035. In the first budget period of this project, the bench-scale phase-changing CO2 capture process was designed using data and operating experience generated under a previous project (ARPA-e project DE-AR0000084). Sizing and specification of all major unit operations was completed, including detailed process and instrumentation diagrams. The system was designed to operate over a wide range of operating conditions to allow for exploration of the effect of process variables on CO2 capture performance.

  9. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    Science.gov (United States)

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

  10. Flexible Bench-Scale Recirculating Flow CPC Photoreactor for Solar Photocatalytic Degradation of Methylene Blue Using Removable TiO2 Immobilized on PET Sheets

    Directory of Open Access Journals (Sweden)

    Doaa M. EL-Mekkawi

    2016-01-01

    Full Text Available TiO2 immobilized on polyethylene (PET nonwoven sheet was used in the solar photocatalytic degradation of methylene blue (MB. TiO2 Evonik Aeroxide P25 was used in this study. The amount of loaded TiO2 on PET was approximately 24%. Immobilization of TiO2 on PET was conducted by dip coating process followed by exposing to mild heat and pressure. TiO2/PET sheets were wrapped on removable Teflon rods inside home-made bench-scale recirculating flow Compound Parabolic Concentrator (CPC photoreactor prototype (platform 0.7 × 0.2 × 0.4 m3. CPC photoreactor is made up of seven low iron borosilicate glass tubes connected in series. CPC reflectors are made of stainless steel 304. The prototype was mounted on a platform tilted at 30°N local latitude in Cairo. A centrifugal pump was used to circulate water containing methylene blue (MB dye inside the glass tubes. Efficient photocatalytic degradation of MB using TiO2/PET was achieved upon the exposure to direct sunlight. Chemical oxygen demand (COD analyses reveal the complete mineralization of MB. Durability of TiO2/PET composite was also tested under sunlight irradiation. Results indicate only 6% reduction in the amount of TiO2 after seven cycles. No significant change was observed for the physicochemical characteristics of TiO2/PET after the successive irradiation processes.

  11. Bench Scale Process for Low Cost CO2 Capture Using a Phase-Changing Absorbent: Topical Report EH&S Risk Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Westendorf, Tiffany; Farnum, Rachel; Perry, Robert; Herwig, Mark; Giolando, Salvatore; Green, Dianne; Morall, Donna

    2016-05-11

    GE Global Research was contracted by the Department of Energy to design and build a bench-scale process for a novel phase-changing aminosilicone-based CO2 capture solvent (award number DEFE0013687). As part of this program, a technology EH&S assessment (Subtask 5.1) has been completed for a CO2 capture system for a 550 MW coal-fired power plant. The assessment focuses on two chemicals used in the process, the aminosilicone solvent, GAP-0, and dodecylbenzenesulfonic acid (DDBSA), the GAP-0 carbamate formed upon reaction of the GAP-0 with CO2, and two potential byproducts formed in the process, GAP-0/SOx salts and amine-terminated, urea-containing silicone (also referred to as “ureas” in this report). The EH&S assessment identifies and estimates the magnitude of the potential air and water emissions and solid waste generated by the process and reviews the toxicological profiles of the chemicals associated with the process. Details regarding regulatory requirements, engineering controls, and storage and handling procedures are also provided in the following sections.

  12. Bench-Scale Development of a Non-Aqueous Solvent (NAS) CO2 Capture Process for Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lail, Marty

    2017-09-12

    The project aimed to advance RTI’s non-aqueous amine solvent technology by improving the solvent to reduce volatility, demonstrating long-term continuous operation at lab- (0.5 liters solvent) and bench-scale (~120 liters solvent), showing low reboiler heat duty measured during bench-scale testing, evaluating degradation products, building a rate-based process model, and evaluating the techno-economic performance of the process. The project team (RTI, SINTEF, Linde Engineering) and the technology performed well in each area of advancement. The modifications incorporated throughout the project enabled the attainment of target absorber and regenerator conditions for the process. Reboiler duties below 2,000 kJt/kg CO2 were observed in a bench-scale test unit operated at RTI.

  13. Immobilized lysozyme for the continuous lysis of lactic bacteria in wine: Bench-scale fluidized-bed reactor study.

    Science.gov (United States)

    Cappannella, Elena; Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Bavaro, Teodora; Esti, Marco

    2016-11-01

    Lysozyme from hen egg white (HEWL) was covalently immobilized on spherical supports based on microbial chitosan in order to develop a system for the continuous, efficient and food-grade enzymatic lysis of lactic bacteria (Oenococcus oeni) in white and red wine. The objective is to limit the sulfur dioxide dosage required to control malolactic fermentation, via a cell concentration typical during this process. The immobilization procedure was optimized in batch mode, evaluating the enzyme loading, the specific activity, and the kinetic parameters in model wine. Subsequently, a bench-scale fluidized-bed reactor was developed, applying the optimized process conditions. HEWL appeared more effective in the immobilized form than in the free one, when the reactor was applied in real white and red wine. This preliminary study suggests that covalent immobilization renders the enzyme less sensitive to the inhibitory effect of wine flavans. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Investigation of E. coli and Virus Reductions Using Replicate, Bench-Scale Biosand Filter Columns and Two Filter Media

    Directory of Open Access Journals (Sweden)

    Mark Elliott

    2015-08-01

    Full Text Available The biosand filter (BSF is an intermittently operated, household-scale slow sand filter for which little data are available on the effect of sand composition on treatment performance. Therefore, bench-scale columns were prepared according to the then-current (2006–2007 guidance on BSF design and run in parallel to conduct two microbial challenge experiments of eight-week duration. Triplicate columns were loaded with Accusand silica or crushed granite to compare virus and E. coli reduction performance. Bench-scale experiments provided confirmation that increased schmutzdecke growth, as indicated by decline in filtration rate, is the primary factor causing increased E. coli reductions of up to 5-log10. However, reductions of challenge viruses improved only modestly with increased schmutzdecke growth. Filter media type (Accusand silica vs. crushed granite did not influence reduction of E. coli bacteria. The granite media without backwashing yielded superior virus reductions when compared to Accusand. However, for columns in which the granite media was first backwashed (to yield a more consistent distribution of grains and remove the finest size fraction, virus reductions were not significantly greater than in columns with Accusand media. It was postulated that a decline in surface area with backwashing decreased the sites and surface area available for virus sorption and/or biofilm growth and thus decreased the extent of virus reduction. Additionally, backwashing caused preferential flow paths and deviation from plug flow; backwashing is not part of standard BSF field preparation and is not recommended for BSF column studies. Overall, virus reductions were modest and did not meet the 5- or 3-log10 World Health Organization performance targets.

  15. An alternative process to treat boiler feed water for reuse.

    Science.gov (United States)

    Guirgis, Adel; Ghosh, Jyoti P; Achari, Gopal; Langford, Cooper H; Banerjee, Daliya

    2012-09-01

    A bench-scale process to treat boiler feed water for reuse in steam generation was developed. Industrial water samples from a steam-assisted gravity drainage plant in northern Alberta, Canada, were obtained and samples characterized. The technology, which consists of coagulation-settling to remove oil/grease and particulates followed by an advanced oxidative treatment, led to clean water samples with negligible organic carbon. Coagulation followed by settling removed most particulates and some insoluble organics. The advanced oxidative treatment removed any remaining color in the samples, decreased the organic content to near-zero, and provided water ready for reuse.

  16. Experience gained in bench scale and pilot scale fluidised bed processing

    CSIR Research Space (South Africa)

    Hadley, TD

    2005-01-01

    Full Text Available capture to reduce the sulphur dioxide off-gas content. Additionally, work has been conducted on a number of sulphur bearing ores. More recently attention has been placed on the oxidative and reductive roasting of ilmenite to affect the downstream recovery...

  17. Cyanobacteria, Toxins and Indicators: Full-Scale Monitoring & Bench-Scale Treatment Studies

    Science.gov (United States)

    Summary of: 1) Lake Erie 2014 bloom season full-scale treatment plant monitoring data for cyanobacteria and cyanobacteria toxins; 2) Follow-up work to examine the impact of pre-oxidation on suspensions of intact toxin-producing cyanobacterial cells.

  18. Pyrosequencing Analysis of Bench-Scale Nitrifying BiofiltersRemoving Trihalomethanes

    Science.gov (United States)

    The bacterial biofilm communities in four nitrifying biofilters degrading regulated drinking water trihalomethanes were characterized by 454 pyrosequencing. The three most abundant phylotypes based on total diversity were Nitrosomonas (70%), Nitrobacter (14%), and Chitinophagace...

  19. Experimental and modelling studies on continuous synthesis and refining of biodiesel in a dedicated bench scale unit using centrifugal contactor separator technology

    NARCIS (Netherlands)

    Abduh, Muhammad Yusuf; Martinez, Alberto Fernandez; Kloekhorst, Arjan; Manurung, Robert; Heeres, Hero J.

    Continuous synthesis and refining of biodiesel (FAME) using a laboratory scale bench scale unit was explored. The unit consists of three major parts: (i) a continuous centrifugal contactor separator (CCCS) to perform the reaction between sunflower oil and methanol; (ii) a washing unit for the crude

  20. Bench-Scale and Pilot-Scale Treatment Technologies for the ...

    Science.gov (United States)

    Coal mine water (CMW) is typically treated to remove suspended solids, acidity, and soluble metals, but high concentrations of total dissolved solids (TDS) have been reported to impact the environment at several CMW discharge points. Consequently, various states have established TDS wastewater regulations and the US EPA has proposed a benchmark conductivity limit to reduce TDS impacts in streams near mining sites. Traditional CMW treatment effectively removes some TDS components, but is not effective in removing major salt ions due to their higher solubility. This paper describes the basic principles, effectiveness, advantages and disadvantages of various TDS removal technologies (adsorption, bioremediation, capacitive deionization, desalination, electro-chemical ion exchange, electrocoagulation, electrodialysis, ion exchange, membrane filtration, precipitation, and reverse osmosis) that have at least been tested in bench- and pilot-scale experiments. Recent discussions about new regulations to include total dissolved solids TDS) limits would propel interest in the TDS removal technologies focused on coal mine water. TDS removal is not a new concept and has been developed using different technologies for a number of applications, but coal mine water has unique characteristics (depending on the site, mining process, and solid-water-oxygen interactions), which make it unlikely to have a single technology predominating over others. What are some novel technolog

  1. Bench Scale Treatability Studies of Contaminated Soil Using Soil Washing Technique

    OpenAIRE

    Gupta, M. K.; Srivastava, R. K.; Singh, A. K.

    2010-01-01

    Soil contamination is one of the most widespread and serious environmental problems confronting both the industrialized as well as developing nations like India. Different contaminants have different physicochemical properties, which influence the geochemical reactions induced in the soils and may bring about changes in their engineering and environmental behaviour. Several technologies exist for the remediation of contaminated soil and water. In the present study soil washing technique using...

  2. Removal of Arsenite from Water by Ce-Al-Fe Trimetal Oxide Adsorbent: Kinetics, Isotherms, and Thermodynamics

    Directory of Open Access Journals (Sweden)

    Cuizhen Sun

    2016-01-01

    Full Text Available Ce-Al-Fe trimetal oxide adsorbent was prepared. The morphology characteristics of the new adsorbent were analysed by the transmission electron microscope (SEM method. The SEM results implied its ability in the adsorption of As (III. To verify the analyses, bench-scale experiments were performed for the removal of As (III from water. In the experiments of adsorption, As (III adsorption capacity of the trimetal oxide adsorbent was presented significantly higher than activated aluminium oxide and activated carbon. As (III adsorption kinetics resembled pseudo-second-order adsorption mode. When initial As (III concentration was 3, 8, and 10 mg·L−1, the maximum adsorption capacity achieved was 1.48, 3.73, and 5.12 mg·g−1, respectively. In addition, the experimental adsorption data were described well by the Freundlich adsorption isotherm model at 20, 30, and 40°C. The enthalpy change (ΔS, the standard free energy (ΔG, and entropy change (ΔH indicated that the nature of As (III adsorption was exothermic and spontaneous with increasing randomness on the interface of solid and liquid. And the adsorption mechanism can be interpreted as chemisorption with As (III multilayer coverage formation on the adsorbent surface.

  3. Bench-scale studies on capture of mercury on mineral non-carbon based sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion; Utah Univ., Salt Lake City, UT (United States). Dept. of Chemical Engineering; Wendt, Jost O.L. [Utah Univ., Salt Lake City, UT (United States). Dept. of Chemical Engineering; Zhang, Junying; Zheng, Chuguang [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

    2013-07-01

    A new high-temperature, mineral non-carbon based dispersed sorbent derived from paper recycling products has been shown to capture mercury at high temperatures in excess of 600 C. The sorbent is consisted of kaolinite/calcite/lime mixtures. Experiments have been conducted on chemi-sorption of elemental mercury in air on a packed bed. The sorption occurs at temperatures between 600 and 1,100 C and requires activation of the minerals contained within the sorbents. Mercury capture is dominated by temperature and capture on sorbents over long time scales. The capture shows a maximum effectiveness at 1,000 C and increases monotonically with temperature. The presence of oxygen is also the required. Freshly activated sorbent is the most effective, and deactivation of sorbents occurs at high temperatures with long pre-exposure times. This activation is suspected to involve a solid-solid reaction between intimately mixed calcium oxide and silica that are both contained within the sorbent. Deactivation occurs at temperatures higher than 1,000 C, and this is due to melting of the substrate and pore closure. The situation in packed beds is complicated because the bed also shrinks, thus allowing channeling and by-passing, and consequent ambiguities in determining sorbent saturation. Sorbent A had significantly greater capacity for mercury sorption than did Sorbent B, for all temperatures and exposure time examined. The effect of SiO{sub 2} on poor Sorbent B is much larger than sorbent A.

  4. Bench Scale Treatability Studies of Contaminated Soil Using Soil Washing Technique

    Directory of Open Access Journals (Sweden)

    M. K. Gupta

    2010-01-01

    Full Text Available Soil contamination is one of the most widespread and serious environmental problems confronting both the industrialized as well as developing nations like India. Different contaminants have different physicochemical properties, which influence the geochemical reactions induced in the soils and may bring about changes in their engineering and environmental behaviour. Several technologies exist for the remediation of contaminated soil and water. In the present study soil washing technique using plain water with surfactants as an enhancer was used to study the remediation of soil contaminated with (i an organic contaminant (engine lubricant oil and (ii an inorganic contaminant (heavy metal. The lubricant engine oil was used at different percentages (by dry weight of the soil to artificially contaminate the soil. It was found that geotechnical properties of the soil underwent large modifications on account of mixing with the lubricant oil. The sorption experiments were conducted with cadmium metal in aqueous medium at different initial concentration of the metal and at varying pH values of the sorbing medium. For the remediation of contaminated soil matrices, a nonionic surfactant was used for the restoration of geotechnical properties of lubricant oil contaminated soil samples, whereas an anionic surfactant was employed to desorb cadmium from the contaminated soil matrix. The surfactant in case of soil contaminated with the lubricant oil was able to restore properties to an extent of 98% vis-à-vis the virgin soil, while up to 54% cadmium was desorbed from the contaminated soil matrix in surfactant aided desorption experiments.

  5. Fe-based heterogeneous catalysts for the Fischer-Tropsch reaction: Sonochemical synthesis and bench-scale experimental tests.

    Science.gov (United States)

    Comazzi, Alberto; Pirola, Carlo; Longhi, Mariangela; Bianchi, Claudia L M; Suslick, Kenneth S

    2017-01-01

    The sonochemical synthesis of nanostructured materials owes its origins to the extreme conditions created during acoustic cavitation, i.e., the formation of localized hot spots in the core of collapsing bubbles in a liquid irradiated with high intensity ultrasound (US). In particular, in the present work a sonochemical synthesis has been investigated for the production of three different iron-based samples supported on SiO2 and loaded with different metals and promoters (10 %wt of Fe; 30 %wt of Fe; 30 %wt of Fe, 2 %wt of K and 3.75 %wt of Cu) active in the Fischer-Tropsch (FT) process. Sonochemically synthesized heterogeneous catalysts were characterized by BET, XRPD, TPR, ICP, CHN, TEM, SEM and then tested in a fixed bed FT-bench-scale rig fed with a mixture of H2 and CO at a H2/CO molar ratio equal to 2, at activation temperatures of 350-400°C and reaction temperatures of 250-260°C. The experimental results showed that the ultrasonic samples are effective catalysts for the FT process. Notably, increasing the activation temperature increased CO conversion, while product selectivity did not diminish. All the sonochemically prepared samples presented in this work provided better catalytic results compared to the corresponding traditional FT impregnated catalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Physicochemical properties and gasification reactivity of the ultrafine semi-char derived from a bench-scale fluidized bed gasifier

    Science.gov (United States)

    Zhang, Yukui; Zhang, Haixia; Zhu, Zhiping; Na, Yongjie; Lu, Qinggang

    2017-08-01

    Zhundong coalfield is the largest intact coalfield worldwide and fluidized bed gasification has been considered as a promising way to achieve its clean and efficient utilization. The purpose of this study is to investigate the physicochemical properties and gasification reactivity of the ultrafine semi-char, derived from a bench-scale fluidized bed gasifier, using Zhundong coal as fuel. The results obtained are as follows. In comparison to the raw coal, the carbon and ash content of the semi-char increase after partial gasification, but the ash fusion temperatures of them show no significant difference. Particularly, 76.53% of the sodium in the feed coal has released to the gas phase after fluidized bed gasification. The chemical compositions of the semi-char are closely related to its particle size, attributable to the distinctly different natures of diverse elements. The semi-char exhibits a higher graphitization degree, higher BET surface area, and richer meso- and macropores, which results in superior gasification reactivity than the coal char. The chemical reactivity of the semi-char is significantly improved by an increased gasification temperature, which suggests the necessity of regasification of the semi-char at a higher temperature. Consequently, it will be considered feasible that these carbons in the semi-char from fluidized bed gasifiers are reclaimed and reused for the gasification process.

  7. Bench-scale cross flow filtration of Tank S-107 sludge slurries and Tank C-107 supernatant

    Energy Technology Data Exchange (ETDEWEB)

    Geeting, J.G.H.; Reynolds, B.A.

    1996-10-01

    Hanford tank waste filtration experiments were conducted using a bench-scale cross flow filter on 8 wt%, 1.5 wt%, and 0.05 wt% Tank S- 107 sludge slurries and on Tank C-107 supernatant. For comparison, two simulants each with solids loadings of 8 wt% and 0.05 wt% were also tested. The purpose of the tests was to determine the efficacy of cross flow filtration on slurries of various solids loadings. -In addition, filtrate flux dependency on axial velocity and transmembrane pressure was sought so that conditions for future experiments might be better selected. The data gathered are compared to the simulants and three cross flow filtration models. A two- parameter central composite design which tested. transmembrane pressure from 5 to 40 psig and axial Velocity from 3 to 9 ft/s was used for all feeds. The cross flow filter effectively removed solids from the liquid, as 19 of 20 filtrate samples had particle concentrations below the resolution limit of the photon correlation spectrometer used in the Hanford Radiocolloid Laboratory. Radiochemical analysis indicate that all filtrate samples were below Class A waste classification standards for 9OSr and transuranics.

  8. WASTE SOLIDIFICATION BUILDING BENCH SCALE HIGH ACTIVITY WASTE SIMULANT VARIABILITY STUDY FY2008

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, E; Timothy Jones, T; Tommy Edwards, T; Alex Cozzi, A

    2009-03-20

    The primary objective of this task was to perform a variability study of the high activity waste (HAW) acidic feed to determine the impact of feed variability on the quality of the final grout and on the mixability of the salt solution into the dry powders. The HAW acidic feeds were processed through the neutralization/pH process, targeting a final pH of 12. These fluids were then blended with the dry materials to make the final waste forms. A secondary objective was to determine if elemental substitution for cost prohibitive or toxic elements in the simulant affects the mixing response, thus providing a more economical simulant for use in full scale tests. Though not an objective, the HAW simulant used in the full scale tests was also tested and compared to the results from this task. A statistically designed test matrix was developed based on the maximum molarity inputs used to make the acidic solutions. The maximum molarity inputs were: 7.39 HNO{sub 3}, 0.11618 gallium, 0.5423 silver, and 1.1032 'other' metals based on their NO{sub 3}{sup -} contribution. Substitution of the elements aluminum for gallium and copper for silver was also considered in this test matrix, resulting in a total of 40 tests. During the NaOH addition, the neutralization/pH adjustment process was controlled to a maximum temperature of 60 C. The neutralized/pH adjusted simulants were blended with Portland cement and zircon flour at a water to cement mass ratio of 0.30. The mass ratio of zircon flour to Portland cement was 1/12. The grout was made using a Hobart N-50 mixer running at low speed for two minutes to incorporate and properly wet the dry solids with liquid and at medium speed for five minutes for mixing. The resulting fresh grout was measured for three consecutive yield stress measurements. The cured grout was measured for set, bleed, and density. Given the conditions of preparing the grout in this task, all of the grouts were visually well mixed prior to preparing the

  9. Bench-scale gasification of cedar wood--part I: effect of operational conditions on product gas characteristics.

    Science.gov (United States)

    Aljbour, Salah H; Kawamoto, Katsuya

    2013-01-01

    The present study was conducted within the framework of R&D activities on the development of gasification and reforming technologies for energy and chemical recovery from biomass resources. Gasification of the Japanese cedar wood has been investigated under various operating conditions in a bench-scale externally heated updraft gasifier; this was followed by thermal reforming. Parametric tests by varying the residence times, gasification temperatures, equivalence ratios (ERs) and steam-to-carbon (S/C) ratios were performed to determine their effects on the product gas characteristics. Thermodynamic equilibrium calculations were preformed to predict the equilibrium gas composition and compared with the experimental value. We found that the product gas characteristics in terms of the H(2)/CO ratio, CO(2)/CO ratio, and CH(4) and lighter hydrocarbons concentrations are significantly affected by the operating conditions used. Increasing the residence time decreased the CO(2)/CO ratio; however, a nominal effect was noticed on H(2) concentration as a function of the residence time. At sufficient residence time, increasing the temperature led to higher H(2) yields, CO efficiency and higher heating value (HHV) of the product gas. The presence of steam during gasification effectively enhanced the proportion of H(2) in the product gas. However, higher S/C ratio reduced the HHV of the product gas. Increasing the ER from 0 to 0.3 increased the H(2) yields and CO efficiency and decreased the HHV of the product gas. The evolution of CH(4) and lighter hydrocarbons at low gasification temperatures was relatively higher than that at high temperature gasification. The evolution of CH(4) and lighter hydrocarbons at high gasification temperatures hardly varied over the investigated operating conditions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Bench-scale gasification of cedar wood--part II: effect of operational conditions on contaminant release.

    Science.gov (United States)

    Aljbour, Salah H; Kawamoto, Katsuya

    2013-01-01

    Here, we present the evolution profile of tar in the product gas during cedar biomass gasification. We also discuss the evolution of other contaminants (H(2)S, COS, NH(3), HCN, and HCl). The cedar wood was gasified under various operating conditions in a bench-scale externally heated updraft gasifier; this was followed by thermal reforming. Tar levels in the product gas were significantly affected by the operating conditions used. At a gasification temperature of 923 K, there was no clear relation between the evolution of phenolic tar in the product gas as a function of residence time. The evolution of PAH tar at a low gasification temperature was lower than the evolution of phenolic tar. With increasing temperature, the proportion of PAH tar content became significant. At a gasification temperature of 1223 K, increasing the residence time reduced the content of PAH tar owing to a catalytic effect associated with ash generation at high temperatures. Increasing the steam-to-carbon (S/C) ratio under thermal conditions had a slight effect on PAH conversion. However, increasing the equivalence ratio (ER) effectively reduced the tar levels. The conversion of fuel-sulfur and fuel-nitrogen to volatile-sulfur and volatile-nitrogen, respectively, increased with increasing S/C ratio and ER. The evolutions of COS and HCN gases were much smaller than the evolution of H(2)S and NH(3). The evolution of HCl in the product gas decreased slightly with increasing ER. Increasing the S/C ratio decreased the HCl levels in the product gas. The effect of temperature on contaminant levels could not be fully understood due to limited availability of experimental data at various temperatures. We also compare our findings with data in the literature. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Archaeal and bacterial community dynamics and bioprocess performance of a bench-scale two-stage anaerobic digester.

    Science.gov (United States)

    Gonzalez-Martinez, Alejandro; Garcia-Ruiz, Maria Jesus; Rodriguez-Sanchez, Alejandro; Osorio, Francisco; Gonzalez-Lopez, Jesus

    2016-07-01

    Two-stage technologies have been developed for anaerobic digestion of waste-activated sludge. In this study, the archaeal and bacterial community structure dynamics and bioprocess performance of a bench-scale two-stage anaerobic digester treating urban sewage sludge have been studied by the means of high-throughput sequencing techniques and physicochemical parameters such as pH, dried sludge, volatile dried sludge, acid concentration, alkalinity, and biogas generation. The coupled analyses of archaeal and bacterial communities and physicochemical parameters showed a direct relationship between archaeal and bacterial populations and bioprocess performance during start-up and working operation of a two-stage anaerobic digester. Moreover, results demonstrated that archaeal and bacterial community structure was affected by changes in the acid/alkalinity ratio in the bioprocess. Thus, a predominance of the acetoclastic methanogen Methanosaeta was observed in the methanogenic bioreactor at high-value acid/alkaline ratio, while a predominance of Methanomassilicoccaeceae archaea and Methanoculleus genus was observed in the methanogenic bioreactor at low-value acid/alkaline ratio. Biodiversity tag-iTag sequencing studies showed that methanogenic archaea can be also detected in the acidogenic bioreactor, although its biological activity was decreased after 4 months of operation as supported by physicochemical analyses. Also, studies of the VFA producers and VFA consumers microbial populations showed as these microbiota were directly affected by the physicochemical parameters generated in the bioreactors. We suggest that the results obtained in our study could be useful for future implementations of two-stage anaerobic digestion processes at both bench- and full-scale.

  12. Integrated processes for produced water polishing: Enhanced flotation/sedimentation combined with advanced oxidation processes.

    Science.gov (United States)

    Jiménez, Silvia; Micó, María M; Arnaldos, Marina; Ferrero, Enrique; Malfeito, Jorge J; Medina, Francisco; Contreras, Sandra

    2017-02-01

    In this study, bench scale dissolved air flotation (DAF) and settling processes have been studied and compared to a novel flotation technology based on the use of glass microspheres of limited buoyancy and its combination with conventional DAF, (Enhanced DAF or E-DAF). They were evaluated as pretreatments for advanced oxidation processes (AOPs) to polish produced water (PW) for reuse purposes. Settling and E-DAF without air injection showed adequate turbidity and oil and grease (O&G) removals, with eliminations higher than 87% and 90% respectively, employing 70 mg L(-1) of FeCl3 and 83 min of settling time, and 57.9 mg L(-1) of FeCl3, 300 mg L(-1) of microspheres and a flocculation rate of 40 rpm in the E-DAF process. A linear correlation was observed between final O&G concentration and turbidity after E-DAF. In order to polish the O&G content of the effluent even further, to remove soluble compounds as phenol and to take advantage of residual iron after these treatments, Fenton and photo-Fenton reactions were essayed. After 6 h of the Fenton reaction at pH 3, the addition of 1660 mg L(-1) of H2O2 and 133 mg L(-1) of iron showed a maximum O&G elimination of 57.6% and a phenol removal up to 80%. Photo-Fenton process showed better results after 3 h, adding 600 mg L(-1) of H2O2 and 300 mg L(-1) of iron, at pH 3, with a higher fraction of elimination of the O&G content (73.7%) and phenol (95%) compared to the conventional Fenton process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Cultivation of Chlorella sp. using raw dairy wastewater for nutrient removal and biodiesel production: Characteristics comparison of indoor bench-scale and outdoor pilot-scale cultures.

    Science.gov (United States)

    Lu, Weidong; Wang, Zhongming; Wang, Xuewei; Yuan, Zhenhong

    2015-09-01

    The biomass productivity and nutrient removal capacity of simultaneous Chlorella sp. cultivation for biodiesel production and nutrient removal in raw dairy wastewater (RDW) in indoor bench-scale and outdoor pilot-scale photobioreactors were compared. Results from the current work show that maximum biomass productivity in indoor bench-scale cultures can reach 260 mg L(-1) day(-1), compared to that of 110 mg L(-1) day(-1) in outdoor pilot-scale cultures. Maximum chemical oxygen demand (COD), total nitrogen (TN), and total phosphorous (TP) removal rate obtained in indoor conditions was 88.38, 38.34, and 2.03 mg L(-1) day(-1), respectively, this compared to 41.31, 6.58, and 2.74 mg L(-1) day(-1), respectively, for outdoor conditions. Finally, dominant fatty acids determined to be C16/C18 in outdoor pilot-scale cultures indicated great potential for scale up of Chlorella sp. cultivation in RDW for high quality biodiesel production coupling with RDW treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Degradation of diethyl phthalate in treated effluents from an MBR via advanced oxidation processes: effects of nitrate on oxidation and a pilot-scale AOP operation.

    Science.gov (United States)

    Park, J H; Park, C G; Lee, J W; Ko, K B

    2010-01-01

    The major objective of this study was to delineate the oxidation of diethyl phthalate (DEP) in water, using bench-scale UV/H2O2 and O3/H2O2 processes, and to determine the effects of nitrate (NO(3-)-N, 5 mg L(-1)) on this oxidation. The oxidation of DEP was also investigated through a pilot-scale advanced oxidation process (AOP), into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. The bench-scale operation showed that DEP could be oxidized via solely UV oxidation or O3 oxidation. The adverse effect of nitrate on the DEP oxidation was remarkable in the UV/H2O2 process, and the nitrate clearly reduced its oxidation. The adverse effect of nitrate on O3 oxidation was also observed. It was noted, however, that the nitrate clearly enhanced the DEP oxidation in the O3/H2O2 process. A series of pilot-scale AOP operations indicated that the addition of H2O2 enhanced DEP oxidation in both the UV/H2O2 and O3/H2O2 processes. No noticeable adverse effect of nitrate was observed in the NO(3-)-N concentration of about 6.0 mg L(-1), which was naturally contained in the treatment stream. About 52% and 61% of the DEP were oxidized by each of these two oxidation processes in this pilot-scale operation. Both the UV/H2O2 and O3/H2O2 processes appeared to be desirable alternatives for DEP oxidation in treatment effluent streams.

  15. Homogeneous and heterogenized iridium water oxidation catalysts

    Science.gov (United States)

    Macchioni, Alceo

    2014-10-01

    The development of an efficient catalyst for the oxidative splitting of water into molecular oxygen, protons and electrons is of key importance for producing solar fuels through artificial photosynthesis. We are facing the problem by means of a rational approach aimed at understanding how catalytic performance may be optimized by the knowledge of the reaction mechanism of water oxidation and the fate of the catalytic site under the inevitably harsh oxidative conditions. For the purposes of our study we selected iridium water oxidation catalysts, exhibiting remarkable performance (TOF > 5 s-1 and TON > 20000). In particular, we recently focused our attention on [Cp*Ir(N,O)X] (N,O = 2-pyridincarboxylate; X = Cl or NO3) and [IrCl(Hedta)]Na water oxidation catalysts. The former exhibited a remarkable TOF whereas the latter showed a very high TON. Furthermore, [IrCl(Hedta)]Na was heterogenized onto TiO2 taking advantage of the presence of a dandling -COOH functionality. The heterogenized catalyst maintained approximately the same catalytic activity of the homogeneous analogous with the advantage that could be reused many times. Mechanistic studies were performed in order to shed some light on the rate-determining step and the transformation of catalysts when exposed to "oxidative stress". It was found that the last oxidative step, preceding oxygen liberation, is the rate-determining step when a small excess of sacrificial oxidant is used. In addition, several intermediates of the oxidative transformation of the catalyst were intercepted and characterized by NMR, X-Ray diffractometry and ESI-MS.

  16. Supercritical Water Oxidation Data Acquisition Testing

    Energy Technology Data Exchange (ETDEWEB)

    K. M. Garcia

    1996-08-01

    Supercritical Water Oxidation (SCWO) is a high pressure oxidation process that blends air, water, and organic waste material in an oxidizer in which where the temperature and pressure in the oxidizer are maintained above the critical point of water. Supercritical water mixed with hydrocarbons, which would be insoluble at subcritical conditions, forms a homogeneous phase which possesses properties associated with both a gas and a liquid. Hydrocarbons in contact with oxygen and SCW are readily oxidized. These properties of SCW make it an attractive means for the destruction of waste streams containing organic materials. SCWO technology holds great promise for treating mixed wastes in an environmentally safe and efficient manner. In the spring of 1994 the U.S. Department of Energy (DOE) initiated a Supercritical Water Oxidation Data Acquisition Testing (SCWODAT) program. The SCWODAT program provided further information and operational data on the effectiveness of treating both simulated mixed waste and typical Navy hazardous waste using the SCWO technology. The program concentrated on the acquisition of data through pilot plant testing. The Phase I DOE testing used a simulated waste stream that contained a complex machine cutting oil and metals, that acted as surrogates for radionuclides. The Phase II Navy testing included pilot testing using hazardous waste materials to demonstrate the effectiveness of the SCWO technology. The SCWODAT program demonstrated that the SCWO process oxidized the simulated waste stream containing complex machine cutting oil, selected by DOE as representative of one of the most difficult of the organic waste streams for which SCWO had been applied. The simulated waste stream with surrogate metals in solution was oxidized, with a high destruction efficiency, on the order of 99.97%, in both the neutralized and unneutralized modes of operation.

  17. Bench-Scale Development of a Hot Carbonate Absorption Process with Crystallization-Enabled High-Pressure Stripping for Post-Combustion CO{sub 2} Capture

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yongqi; DeVries, Nicholas; Ruhter, David; Manoranjan, Sahu; Ye, Qing; Ye, Xinhuai; Zhang, Shihan; Chen, Scott; Li, Zhiwei; O' Brien, Kevin

    2014-03-31

    A novel Hot Carbonate Absorption Process with Crystallization-Enabled High-Pressure Stripping (Hot-CAP) has been developed by the University of Illinois at Urbana-Champaign and Carbon Capture Scientific, LLC in this three-year, bench-scale project. The Hot-CAP features a concentrated carbonate solution (e.g., K{sub 2}CO{sub 3}) for CO{sub 2} absorption and a bicarbonate slurry (e.g., KHCO{sub 3}) for high-pressure CO{sub 2} stripping to overcome the energy use and other disadvantages associated with the benchmark monoethanolamine (MEA) process. The project was aimed at performing laboratory- and bench-scale experiments to prove its technical feasibility and generate process engineering and scale-up data, and conducting a techno-economic analysis (TEA) to demonstrate its energy use and cost competitiveness over MEA. To meet project goals and objectives, a combination of experimental, modeling, process simulation, and economic analysis studies were applied. Carefully designed and intensive experiments were conducted to measure thermodynamic and reaction engineering data relevant to four major unit operations in the Hot-CAP (i.e., CO{sub 2} absorption, CO{sub 2} stripping, bicarbonate crystallization, and sulfate reclamation). The rate promoters that could accelerate the CO{sub 2} absorption rate into the potassium carbonate/bicarbonate (PCB) solution to a level greater than that into the 5 M MEA solution were identified, and the superior performance of CO{sub 2} absorption into PCB was demonstrated in a bench-scale packed-bed column. Kinetic data on bicarbonate crystallization were developed and applied for crystallizer design and sizing. Parametric testing of high-pressure CO{sub 2} stripping with concentrated bicarbonate-dominant slurries at high temperatures ({>=}140{degrees}C) in a bench-scale stripping column demonstrated lower heat use than with MEA. The feasibility of a modified process for combining SO{sub 2} removal with CO{sub 2} capture was preliminarily

  18. EVALUATION OF THE TREATABILITY OF MUNICIPAL WASTE LANDFILL LEACHATE IN A SBR AND BY COAGULATION-FLOCCULATION ON A BENCH SCALE

    Directory of Open Access Journals (Sweden)

    E. Fleck

    Full Text Available Abstract This article describes bench scale sequential, biological and coagulation-flocculation treatment of mature leachate for the removal of nitrogen and biodegradable and recalcitrant carbonaceous material. The biological stage was conducted on two SBRs, one of which inoculated with nitrifying sludge, another without an inoculum, for 152 and 133 days, respectively. The coagulation-flocculation stage used four coagulants at different doses and pH adjustments. The treatment conducted on the inoculated SBR when a pH control was used produced mean removals of BOD5, COD and TKN of 69.6%, 38.5% and 51.6%, respectively, and practically complete denitrification. Coagulation-flocculation applied to the effluent of the inoculated biological reactor showed a superior effectiveness of the ferric coagulants, when the pH was adjusted to close to 6.0, producing removals of turbidity, COD and true color close to 95%, 78% and 92%, respectively.

  19. Appling hydrolysis acidification-anoxic–oxic process in the treatment of petrochemical wastewater: From bench scale reactor to full scale wastewater treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Changyong [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Research Center of Water Pollution Control Technology, Chinese Research Academy of Environment Sciences, Beijing 100012 (China); Zhou, Yuexi, E-mail: zhouyuexi@263.net [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Research Center of Water Pollution Control Technology, Chinese Research Academy of Environment Sciences, Beijing 100012 (China); Sun, Qingliang [School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Fu, Liya [Research Center of Water Pollution Control Technology, Chinese Research Academy of Environment Sciences, Beijing 100012 (China); School of Environment, Tsinghua University, Beijing 100084 (China); Xi, Hongbo; Yu, Yin [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Research Center of Water Pollution Control Technology, Chinese Research Academy of Environment Sciences, Beijing 100012 (China); Yu, Ruozhen [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    2016-05-15

    Highlights: • Hydrolysis acidification-anoxic–oxic process can be used to treat petrochemical wastewater. • The toxicity and treatability changed significantly after hydrolysis acidification. • The type and concentration of organics reduced greatly after treatment. • The effluent shows low acute toxicity by luminescent bacteria assay. • Advanced treatment is recommended for the effluent. - Abstract: A hydrolysis acidification (HA)-anoxic–oxic (A/O) process was adopted to treat a petrochemical wastewater. The operation optimization was carried out firstly by a bench scale experimental reactor. Then a full scale petrochemical wastewater treatment plant (PCWWTP, 6500 m{sup 3} h{sup −1}) was operated with the same parameters. The results showed that the BOD{sub 5}/COD of the wastewater increased from 0.30 to 0.43 by HA. The effluent COD was 54.4 mg L{sup −1} for bench scale reactor and 60.9 mg L{sup −1} for PCWWTP when the influent COD was about 480 mg L{sup −1} on optimized conditions. The organics measured by gas chromatography-mass spectrometry (GC–MS) reduced obviously and the total concentration of the 5 organics (1,3-dioxolane, 2-pentanone, ethylbenzene, 2-chloromethyl-1,3-dioxolane and indene) detected in the effluent was only 0.24 mg L{sup −1}. There was no obvious toxicity of the effluent. However, low acute toxicity of the effluent could be detected by the luminescent bacteria assay, indicating the advanced treatment is needed. The clone library profiling analysis showed that the dominant bacteria in the system were Acidobacteria, Proteobacteria and Bacteriodetes. HA-A/O process is suitable for the petrochemical wastewater treatment.

  20. Supercritical water oxidation - Microgravity solids separation

    Science.gov (United States)

    Killilea, William R.; Hong, Glenn T.; Swallow, Kathleen C.; Thomason, Terry B.

    1988-01-01

    This paper discusses the application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in-long term manned space missions. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free supercritical fluid reactor effluent. Supercritical water reactor/solids separator designs capable of removing precipitated solids from the process' supercritical fluid in zero- and low- gravity environments are developed and evaluated. Preliminary experiments are then conducted to test the concepts. Feed materials for the experiments are urine, feces, and wipes with the addition of reverse osmosis brine, the rejected portion of processed hygiene water. The solid properties and their influence on the design of several oxidation-reactor/solids-separator configurations under study are presented.

  1. Water clustering on nanostructured iron oxide films

    DEFF Research Database (Denmark)

    Merte, Lindsay Richard; Bechstein, Ralf; Peng, G.

    2014-01-01

    , but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer...... islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous...

  2. Indoor Secondary Pollutants from Household Product Emissions inthe Presence of Ozone: A Bench-Scale Chamber Study

    Energy Technology Data Exchange (ETDEWEB)

    Destaillats, Hugo; Lunden, Melissa M.; Singer, Brett C.; Coleman,Beverly K.; Hodgson, Alfred T.; Weschler, Charles J.; Nazaroff, William W.

    2005-10-01

    Ozone-driven chemistry is a major source of indoor secondary pollutants of health concern. This study investigates secondary air pollutants formed from reactions between constituents of household products and ozone. Gas-phase product emissions were introduced along with ozone at constant rates into a 198-L Teflon-lined reaction chamber. Gas-phase concentrations of reactive terpenoids and oxidation products were measured. Formaldehyde was a predominant oxidation byproduct for the three studied products, with yields under most conditions of 20-30% with respect to ozone consumed. Acetaldehyde, acetone, glycolaldehyde, formic acid and acetic acid were each also detected for two or three of the products. Immediately upon mixing of reactants, a scanning mobility particle sizer detected particle nucleation events that were followed by a significant degree of ultrafine particle growth. The production of secondary gaseous pollutants and particles depended primarily on the ozone level and was influenced by other parameters such as the air-exchange rate. Hydroxyl radical concentrations in the range 0.04-200 x 10{sup 5} molecules cm{sup -3} were measured. OH concentrations were observed to vary strongly with residual ozone level in the chamber, which was in the range 1-25 ppb, as is consistent with expectations from a simplified kinetic model. In a separate test, we exposed the dry residue of two products to ozone in the chamber and observed the formation of gas-phase and particle-phase secondary oxidation products.

  3. Methane oxidation in anoxic lake waters

    Science.gov (United States)

    Su, Guangyi; Zopfi, Jakob; Niemann, Helge; Lehmann, Moritz

    2017-04-01

    Freshwater habitats such as lakes are important sources of methante (CH4), however, most studies in lacustrine environments so far provided evidence for aerobic methane oxidation only, and little is known about the importance of anaerobic oxidation of CH4 (AOM) in anoxic lake waters. In marine environments, sulfate reduction coupled to AOM by archaea has been recognized as important sinks of CH4. More recently, the discorvery of anaerobic methane oxidizing denitrifying bacteria represents a novel and possible alternative AOM pathway, involving reactive nitrogen species (e.g., nitrate and nitrite) as electron acceptors in the absence of oxygen. We investigate anaerobic methane oxidation in the water column of two hydrochemically contrasting sites in Lake Lugano, Switzerland. The South Basin displays seasonal stratification, the development of a benthic nepheloid layer and anoxia during summer and fall. The North Basin is permanently stratified with anoxic conditions below 115m water depth. Both Basins accumulate seasonally (South Basin) or permanently (North Basin) large amounts of CH4 in the water column below the chemocline, providing ideal conditions for methanotrophic microorganisms. Previous work revealed a high potential for aerobic methane oxidation within the anoxic water column, but no evidence for true AOM. Here, we show depth distribution data of dissolved CH4, methane oxidation rates and nutrients at both sites. In addition, we performed high resolution phylogenetic analyses of microbial community structures and conducted radio-label incubation experiments with concentrated biomass from anoxic waters and potential alternative electron acceptor additions (nitrate, nitrite and sulfate). First results from the unamended experiments revealed maximum activity of methane oxidation below the redoxcline in both basins. While the incubation experiments neither provided clear evidence for NOx- nor sulfate-dependent AOM, the phylogenetic analysis revealed the

  4. Novel two stage bio-oxidation and chlorination process for high strength hazardous coal carbonization effluent.

    Science.gov (United States)

    Manekar, Pravin; Biswas, Rima; Karthik, Manikavasagam; Nandy, Tapas

    2011-05-15

    Effluent generated from coal carbonization to coke was characterized with high organic content, phenols, ammonium nitrogen, and cyanides. A full scale effluent treatment plant (ETP) working on the principle of single stage carbon-nitrogen bio-oxidation process (SSCNBP) revealed competition between heterotrophic and autotrophic bacteria in the bio-degradation and nitrification process. The effluent was pretreated in a stripper and further combined with other streams to treat in the SSCNBP. Laboratory studies were carried on process and stripped effluents in a bench scale model of ammonia stripper and a two stage bio-oxidation process. The free ammonia removal efficiency of stripper was in the range 70-89%. Bench scale studies of the two stage bio-oxidation process achieved a carbon-nitrogen reduction at 6 days hydraulic retention time (HRT) operating in an extended aeration mode. This paper addresses the studies on selection of a treatment process for removal of organic matter, phenols, cyanide and ammonia nitrogen. The treatment scheme comprising ammonia stripping (pretreatment) followed by the two stage bio-oxidation and chlorination process met the Indian Standards for discharge into Inland Surface Waters. This treatment process package offers a techno-economically viable treatment scheme to neuter hazardous effluent generated from coal carbonization process. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Water Clustering on Nanostructured Iron Oxide Films

    Energy Technology Data Exchange (ETDEWEB)

    Merte, L. R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Laegsgaard, E.; Wendt, Stefen; Mavrikakis, Manos; Besenbacher, Fleming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule–molecule and molecule–surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire´-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the are film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire´ structure.

  6. Water clustering on nanostructured iron oxide films

    Science.gov (United States)

    Merte, Lindsay R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Lægsgaard, Erik; Wendt, Stefan; Mavrikakis, Manos; Besenbacher, Flemming

    2014-06-01

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moiré-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

  7. Nano-sized layered Mn oxides as promising and biomimetic water oxidizing catalysts for water splitting in artificial photosynthetic systems.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Heidari, Sima; Amini, Emad; Khatamian, Masoumeh; Carpentier, Robert; Allakhverdiev, Suleyman I

    2014-04-05

    One challenge in artificial photosynthetic systems is the development of artificial model compounds to oxidize water. The water-oxidizing complex of Photosystem II which is responsible for biological water oxidation contains a cluster of four Mn ions bridged by five oxygen atoms. Layered Mn oxides as efficient, stable, low cost, environmentally friendly and easy to use, synthesize, and manufacture compounds could be considered as functional and structural models for the site. Because of the related structure of these Mn oxides and the catalytic centre of the active site of the water oxidizing complex of Photosystem II, the study of layered Mn oxides may also help to understand more about the mechanism of water oxidation by the natural site. This review provides an overview of the current status of layered Mn oxides in artificial photosynthesis and discuss the sophisticated design strategies for Mn oxides as water oxidizing catalysts. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. A bench-scale study on the removal and recovery of phosphate by hydrous zirconia-coated magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe; Fang, Wenkan; Xing, Mingchao; Wu, Deyi, E-mail: dywu@sjtu.edu.cn

    2017-02-15

    Owing to the easy magnetic separation from water for reuse, magnetic nanoparticles have drawn great interest as adsorbents. Herein hydrous zirconia-coated magnetite nanoparticles (Fe{sub 3}O{sub 4}@ZrO{sub 2}) were created by a facile method and a bench–scale study was undertaken to evaluate its effectiveness and mechanism to remove phosphate at low concentrations. Results indicated that phosphate removal by Fe{sub 3}O{sub 4}@ZrO{sub 2} was fast (95% of phosphate removal within 10 min) and nearly complete removal could be achieved at the adsorbent dosage >0.6 g/L. In tap water or wastewater where competitive anions coexist, regulation of pH was found to be quite effective to augment the performance of phosphate removal. In pH–lowered adsorption systems, phosphate removal followed a good pattern similarly to pure water, i.e., a continuous high efficiency removal followed by a rapid saturation. Adsorption–desorption–regeneration studies showed that Fe{sub 3}O{sub 4}@ZrO{sub 2} could be repeatedly used for phosphate removal and adsorbed phosphate could be stripped for recovery. The fractionation of adsorbed phosphorus suggested that NaOH-P fraction was dominant. We also found that the adsorption reaction of phosphate with Fe{sub 3}O{sub 4}@ZrO{sub 2} shifted the isoelectric point of Fe{sub 3}O{sub 4}@ZrO{sub 2} from ~9.0 to ~3.0. FTIR measurements further showed the direct coordination of phosphate onto zirconium by replacement of hydroxyl groups. The formation of the monodentate (ZrO)PO{sub 2}(OH) complex was proposed. - Highlights: • Hydrous zirconia–coated magnetite was used for phosphate capture. • Regulation of pH was able to enhance P removal in the presence of coexisting ions. • Phosphate was coordinated onto zirconium by replacement of hydroxyl groups. • The material could be easily separated from water for reuse by a magnet. • Desorption of phosphate from the material could be achieved with NaOH treatment.

  9. Supercritical water oxidation treatment of textile sludge.

    Science.gov (United States)

    Zhang, Jie; Wang, Shuzhong; Li, Yanhui; Lu, Jinling; Chen, Senlin; Luo, XingQi

    2017-08-01

    In this work, we studied the supercritical water oxidation (SCWO) of the textile sludge, the hydrothermal conversion of typical textile compounds and the corrosion properties of stainless steel 316. Moreover, the influence mechanisms of NaOH during these related processes were explored. The results show that decomposition efficiency for organic matter in liquid phase of the textile sludge was improved with the increment of reaction temperature or oxidation coefficient. However, the organic substance in solid phase can be oxidized completely in supercritical water. Serious coking occurred during the high pressure water at 250-450°C for the Reactive Orange 7, while at 300 and 350°C for the polyvinyl alcohol. The addition of NaOH not only accelerated the destruction of organic contaminants in the SCWO reactor, but effectively inhibited the dehydration conversion of textile compounds during the preheating process, which was favorable for the treatment system of textile sludge. The corrosion experiment results indicate that the stainless steel 316 could be competent for the body materials of the reactor and the heat exchangers. Furthermore, there was prominent enhancement of sodium hydroxide for the corrosion resistance of 316 in subcritical water. On the contrary the effect was almost none during SCWO.

  10. Investigation of mixing enhancement in porous media under helical flow conditions: 3-D bench-scale experiments

    DEFF Research Database (Denmark)

    Chiogna, Gabriele; Ye, Yu; Cirpka, Olaf A.

    2017-01-01

    Lateral mass exchange at the fringe of solute plumes is a fundamental process leading to plume dilution and reactive mixing. Mass transfer between the plume and ambient water can be considerably enhanced by helical flow occurring in three-dimensional heterogeneous anisotropic porous media [1-3]. We...... performed steady-state conservative tracer experiments in a fully three-dimensional flow-through chamber to investigate the effects of helical flow on plume spiraling and deformation, as well as on its dilution [4]. Helical flow was created by packing the porous medium in angled stripes of materials...... with different grain sizes to create blocks with macroscopically anisotropic hydraulic conductivity. The hydraulic conductivity of the blocks was varied in different experiments. Solute concentrations and flow rates were measured at high spatial resolution for samples collected at 49 outlet ports. This allowed...

  11. Greenlighting Photoelectrochemical Oxidation of Water by Iron Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Wook; Riha, Shannon C.; DeMarco, Erica J.; Martinson, Alex B. F.; Farha, Omar K.; Hupp, Joseph T.

    2014-12-23

    Hematite (alpha-Fe2O3) is one of just a few candidate electrode materials that possess all of the following photocatalyst-essential properties for scalable application to water oxidation: excellent stability, earth-abundance, suitability positive valence-band-edge energy, and significant visible light absorptivity. Despite these merits, hematites modest oxygen evolution reaction kinetics and its poor efficiency in delivering photogenerated holes, especially holes generated by green photons, to the electrode/solution interface, render it ineffective as a practical water-splitting catalyst. Here we show that hole delivery and catalytic utilization can be substantially improved through Ti alloying, provided that the alloyed material is present in ultrathin-thin-film form. Notably, the effects are most pronounced for charges photogenerated by photons with energy comparable to the band gap for excitation of Fe(3d) -> Fe(3d) transitions (i.e., green photons). Additionally, at the optimum Ti substitution level the lifetimes of surface-localized holes, competent for water oxidation, are extended. Together these changes explain an overall improvement in photoelectrochemical performance, especially enhanced internal quantum efficiencies, observed upon Ti(IV) incorporation.

  12. Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

    Science.gov (United States)

    Shelton, Timothy L.; Bensema, Bronwyn L.; Brune, Nicholas K.; Wong, Christopher; Yeh, Max; Osterloh, Frank E.

    2017-01-01

    Hematite has attracted considerable interest as a photoanode material for water oxidation under visible illumination. Here, we explore the limits of photocatalytic water oxidation activity with iron (III) oxide hydroxide nanocrystals and NaIO4 as a sacrificial electron acceptor (E=1.63 V NHE at pH=0.5). The sol was prepared by hydrolysis of FeCl3 in boiling 0.002-M HCl solution and confirmed to mainly consist of ß-FeO(OH) (akaganéite) particles with 5 to 15 nm diameter. From a 0.01 M aqueous NaIO4 solution, the sol evolves between 4.5 and 35.2 μmol O2 h-1, depending on pH, light intensity (>400 nm, 290 to 700 mW cm-2), ß-FeO(OH), and NaIO4 concentration. The activity increases with pH, and depends linearly on light intensity and photocatalyst amount, and it varies with sacrificial electron donor concentration. Under optimized conditions, the apparent quantum efficiency is 0.19% (at 400 nm and 460 mW cm-2), and the turnover number is 2.58 based on total ß-FeO(OH). Overall, the efficiency of the ß-FeO(OH)/NaIO4 photocatalytic system is limited by electron hole recombination and by particle aggregation over longer irradiation times (24 h). Lastly, surface photovoltage measurements on ß-FeO(OH) films on fluorine doped tin oxide substrate confirm a 2.15 eV effective band gap for the material.

  13. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier. Fourth quarterly report, July 1, 1985--September 30, 1985

    Energy Technology Data Exchange (ETDEWEB)

    Ciliberti, D.F.; Lippert, T.E.

    1985-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  14. Bench scale model studies on sanitary landfill leachate treatment with M. oleifera seed extract and hollow fibre micro-filtration membrane

    Directory of Open Access Journals (Sweden)

    S. A. Muyibi

    2002-10-01

    Full Text Available A laboratory-based study using a Bench Scale model of four unit operations made up of coagulation (using Moringa oleifera seed extract as a coagulant, flocculation, sedimentation and micro-filtration, have been adopted to treat the leachate from Air Hitman Sanitary Landfill at Puchong in Malaysia. M. oleifera dosages of 150 and 175 mg/L had achieved 43.8% Cadmium removal, 21.2% Total Chromium removal, 66.8% Lead removal and 16% Iron removal. It also removed 55.4% of Total Suspended Solids, 10% of Total Dissolved Solids and 24.2% of Volatile Suspended Solids. Micro-filtration hollow fibre membrane decreased the turbidity, total suspended solids, total dissolved solids, volatile suspended solids, and organic matter in the leachate by 98.3%, 96.7%, 20.8%, 36.6% and 21.9% respectively. Overall heavy metals removal after micro-filtration using hollow fibre membrane was 94% for Cadmium, 29.8% for Total Chromium, 73.2% for Lead, and 18.3% for Iron. The results have shown that M. oleifera is a promising natural polymer for removing heavy metals from leachates and may be used as a pre-treatment to eliminate a portion of the toxic heavy metals, which limits the activity of micro organisms in the leachates.

  15. Numerical Studies of the Gas-Solid Hydrodynamics at High Temperature in the Riser of a Bench-Scale Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Maximilian J. Hodapp

    2012-01-01

    Full Text Available The hydrodynamics of circulating fluidized beds (CFBs is a complex phenomenon that can drastically vary depending on operational setup and geometrical configuration. A research of the literature shows that studies for the prediction of key variables in CFB systems operating at high temperature still need to be implemented aiming at applications in energy conversion, such as combustion, gasification, or fast pyrolysis of solid fuels. In this work the computational fluid dynamics (CFD technique was used for modeling and simulation of the hydrodynamics of a preheating gas-solid flow in a cylindrical bed section. For the CFD simulations, the two-fluid approach was used to represent the gas-solid flow with the k-epsilon turbulence model being applied for the gas phase and the kinetic theory of granular flow (KTGF for the properties of the dispersed phase. The information obtained from a semiempirical model was used to implement the initial condition of the simulation. The CFD results were in accordance with experimental data obtained from a bench-scale CFB system and from predictions of the semiempirical model. The initial condition applied in this work was shown to be a viable alternative to a more common constant solid mass flux boundary condition.

  16. Enhanced enzymatic hydrolysis of mild alkali pre-treated rice straw at high-solid loadings using in-house cellulases in a bench scale system.

    Science.gov (United States)

    Narra, Madhuri; Balasubramanian, Velmurugan; James, Jisha P

    2016-06-01

    In the present study, scale-up systems for cellulase production and enzymatic hydrolysis of pre-treated rice straw at high-solid loadings were designed, fabricated and tested in the laboratory. Cellulase production was carried out using tray fermentation at 45 °C by Aspergillus terreus in a temperature-controlled humidity chamber. Enzymatic hydrolysis studies were performed in a horizontal rotary drum reactor at 50 °C with 25 % (w/v) solid loading and 9 FPU g(-1) substrate enzyme load using in-house as well commercial cellulases. Highly concentrated fermentable sugars up to 20 % were obtained at 40 h with an increased saccharification efficiency of 76 % compared to laboratory findings (69.2 %). These findings demonstrate that we developed a simple and less energy intensive bench scale system for efficient high-solid saccharification. External supplementation of commercial β-glucosidase and hemicellulase ensured better hydrolysis and further increased the saccharification efficiency by 14.5 and 20 %, respectively. An attempt was also made to recover cellulolytic enzymes using ultrafiltration module and nearly 79-84 % of the cellulases and more than 90 % of the sugars were recovered from the saccharification mixture.

  17. The stability of aerobic granular sludge treating municipal sludge deep dewatering filtrate in a bench scale sequencing batch reactor.

    Science.gov (United States)

    Long, Bei; Yang, Chang-Zhu; Pu, Wen-Hong; Yang, Jia-Kuan; Shi, Ya-Fei; Wang, Jing; Bai, Jun; Zhou, Xuan-Yue; Jiang, Guo-Sheng; Li, Chun-Yang; Liu, Fu-Biao

    2014-10-01

    Inoculated with mature aerobic granular sludge in a sequencing batch reactor, gradually increasing the proportion of municipal sludge deep dewatering filtrate in influent, aerobic granular sludge was domesticated after 84 days and maintained its structure during the operation. The domesticated AGS was yellowish-brown, dense and irregular spherical shape, average size was 1.49 mm, water content and specific density were 98.13% and 1.0114, the SVI and settling velocity were 40 ml/g and 46.5m/h. After 38 days, NO3(-)-N accumulated obviously in the reactor as lack of carbon sources. When adding 1-3g solid CH3COONa at 4.5 and 5.5h of each cycle from the 57th day, the removal rate of TN rose to above 90% after 20 days, where effective COD removal and denitrification were realized in a single bioreactor. Finally, the removal rates of COD, TP, TN and NH4(+)-N were higher than 95%, 88%, 96% and 99%. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Electrolysis of water on (oxidized) metal surfaces

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2005-01-01

    relations are assumed to be obeyed exactly, this leads to a universal relationship between the catalytic rate and the oxygen binding energy. Finally, we conclude that for systems obeying these relations, there is a limit to how good a water splitting catalyst an oxidized metal surface can become. (c) 2005......Density functional theory calculations are used as the basis for an analysis of the electrochemical process, where by water is split to form molecular oxygen and hydrogen. We develop a method for obtaining the thermochemistry of the electrochemical water splitting process as a function of the bias...... directly from the electronic structure calculations. We consider electrodes of Pt(111) and Au(111) in detail and then discuss trends for a series of different metals. We show that the difficult step in the water splitting process is the formation of superoxy-type (OOH) species on the surface...

  19. Dark oxidation of water in soils

    Directory of Open Access Journals (Sweden)

    Siegfried Fleischer

    2013-12-01

    18O. Water is the only large-scale source of electrons for reduction of CO2 in soils, but it has not been considered as an electron donor because of the very strong oxidation system needed. A high share of soil inorganic material seems to favor the release of O2.To access the supplementary material to this article, please see Supplementary files under Article Tools online.

  20. Photocatalysis: Oxidative Processes in Water Treatment

    Directory of Open Access Journals (Sweden)

    Roman V. Prihod'ko

    2013-01-01

    Full Text Available The efficiency of various homogeneous and heterogeneous systems photocatalytic processes destructive oxidation of organic compounds of different classes is considered. It is shown that photocatalytic methods can significantly increase the speed and depth (up to complete mineralization of decomposition processes of toxicants. The use of photocatalysis (PC in the creation of low-power water treatment technologies is a promising direction in addressing environmental problems of the hydrosphere.

  1. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Sarvi, Bahram; Haghighi, Behzad

    2015-09-14

    Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.

  2. Supercritical water oxidation of products of human metabolism

    Science.gov (United States)

    Tester, Jefferson W.; Orge A. achelling, Richard K. ADTHOMASSON; Orge A. achelling, Richard K. ADTHOMASSON

    1986-01-01

    Although the efficient destruction of organic material was demonstrated in the supercritical water oxidation process, the reaction kinetics and mechanisms are unknown. The kinetics and mechanisms of carbon monoxide and ammonia oxidation in and reaction with supercritical water were studied experimentally. Experimental oxidation of urine and feces in a microprocessor controlled system was performed. A minaturized supercritical water oxidation process for space applications was design, including preliminary mass and energy balances, power, space and weight requirements.

  3. Physical and chemical effects of direct aqueous advanced oxidation processing on green sand foundry mold materials

    Science.gov (United States)

    Clobes, Jason Kenneth

    Iron foundries using the common green sand molding process have increasingly been incorporating aqueous advanced oxidation (AO) systems to reduce the consumption of sand system bentonite clay and coal raw materials by and to decrease their volatile organic compound (VOC) emissions. These AO systems typically use a combination of sonication, ozone aeration, and hydrogen peroxide to treat and recycle slurries of sand system baghouse dust, which is rich in clay and coal. While the overall effects of AO on raw material consumption and organic emissions are known, the mechanisms behind these effects are not well understood. This research examined the effects of bench-scale direct aqueous AO processing on green sand mold materials at the micro level. Bench-scale AO processing, including acoustic sonication, ozone/oxygen aeration, and hydrogen peroxide dramatically decreased the particle sizes of both western bentonite and foundry sand system baghouse dust. Bench-scale AO processing was shown to effectively separate the clay material from the larger silica and coal particles and to extensively break up the larger clay agglomerates. The acoustic sonication component of AO processing was the key contributor to enhanced clay recovery. Acoustic sonication alone was slightly more effective than combined component AO in reducing the particle sizes of the baghouse dust and in the recovery of clay yields in the supernatant during sedimentation experiments. Sedimentation separation results correlated well with the increase in small particle concentrations due to AO processing. Clay suspension viscosity decreased with AO processing due to enhanced dispersion of the particles. X-ray diffraction of freeze-dried baghouse dust indicated that AO processing does not rehydrate calcined montmorillonite and does not increase the level of interlayer water hydration in the dry clays. Zeta potential measurements indicated that AO processing also does not produce any large changes in the

  4. Water defluoridation by aluminium oxide-manganese oxide composite material.

    Science.gov (United States)

    Alemu, Sheta; Mulugeta, Eyobel; Zewge, Feleke; Chandravanshi, Bhagwan Singh

    2014-08-01

    In this study, aluminium oxide-manganese oxide (AOMO) composite material was synthesized, characterized, and tested for fluoride removal in batch experiments. AOMO was prepared from manganese(II) chloride and aluminium hydroxide. The surface area of AOMO was found to be 30.7m2/g and its specific density was determined as 2.78 g/cm3. Detailed investigation of the adsorbent by inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography (for sulphate only) showed that it is composed of Al, Mn, SO4, and Na as major components and Fe, Si, Ca, and Mg as minor components. Thermogravimetric analysis was used to study the thermal behaviour of AOMO. X-ray diffraction analysis showed that the adsorbent is poorly crystalline. The point of zero charge was determined as 9.54. Batch experiments (by varying the proportion of MnO, adsorbent dose, contact time, initial F concentration, and raw water pH) showed that fluoride removal efficiency ofAOMO varied significantly with percentage of MnO with an optimum value of about I11% of manganese oxide in the adsorbent. The optimum dose of the adsorbent was 4 g/L which corresponds to the equilibrium adsorption capacity of 4.8 mg F-/g. Both the removal efficiency and adsorption capacity showed an increasing trend with an increase in initial fluoride concentration of the water. The pH for optimum fluoride removal was found to be in the range between 5 and 7. The adsorption data were analysed using the Freundlich, Langmuir, and Dubinirn-Radushkevich models. The minimum adsorption capacity obtained from the non-linear Freundlich isotherm model was 4.94 mg F-/g and the maximum capacity from the Langmuir isotherm method was 19.2mg F-/g. The experimental data of fluoride adsorption on AOMO fitted well to the Freundlich isotherm model. Kinetic studies showed that the adsorption is well described by a non-linear pseudo-second-order reaction model with an average rate constant of 3

  5. The mechanism of water oxidation catalyzed by nanolayered manganese oxides: New insights.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Abbasi Isaloo, Mohsen

    2015-11-01

    Herein we consider the mechanism of water oxidation by nanolayered manganese oxide in the presence of cerium(IV) ammonium nitrate. Based on membrane-inlet mass spectrometry results, the rate of H2((18))O exchange of μ-O groups on the surface of the nanolayered Mn-K oxide, and studies on water oxidation in the presence of different ratios of acetonitrile/water we propose a mechanism for water oxidation by nanolayered Mn oxides in the presence of cerium(IV) ammonium nitrate. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Mechanism of water transport in graphene oxide laminates.

    Science.gov (United States)

    Deng, Junjiao; You, Yi; Bustamante, Heriberto; Sahajwalla, Veena; Joshi, Rakesh K

    2017-03-01

    It is understood that nano-channels of graphene oxide membranes have a water flow mechanism which is similar to the water flow inside carbon nanotube pores. The water transport mechanisms recently proposed by various researchers suggest that membranes composed of graphene oxide laminates could be regarded as an assembly of many tiny carbon nanotubes stacked together with attached functional groups as spacers.

  7. Bench Scale Process for Low Cost CO2 Capture Using a PhaseChanging Absorbent: Techno-Economic Analysis Topical Report

    Energy Technology Data Exchange (ETDEWEB)

    Miebach, Barbara [GE Global Research, Niskayuna, New York (United States); McDuffie, Dwayne [GE Global Research, Niskayuna, New York (United States); Spiry, Irina [GE Global Research, Niskayuna, New York (United States); Westendorf, Tiffany [GE Global Research, Niskayuna, New York (United States)

    2017-01-27

    The objective of this project is to design and build a bench-scale process for a novel phase-changing CO2 capture solvent. The project will establish scalability and technical and economic feasibility of using a phase-changing CO2 capture absorbent for post-combustion capture of CO2 from coal-fired power plants with 90% capture efficiency and 95% CO2 purity at a cost of $40/tonne of CO2 captured by 2025 and a cost of <$10/tonne of CO2 captured by 2035. This report presents system and economic analysis for a process that uses a phase changing aminosilicone solvent to remove CO2 from pulverized coal (PC) power plant flue gas. The aminosilicone solvent is a pure 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (GAP-0). Performance of the phase-changing aminosilicone technology is compared to that of a conventional carbon capture system using aqueous monoethanolamine (MEA). This analysis demonstrates that the aminosilicone process has significant advantages relative to an MEA-based system. The first-year CO2 removal cost for the phase-changing CO2 capture process is $52.1/tonne, compared to $66.4/tonne for the aqueous amine process. The phase-changing CO2 capture process is less costly than MEA because of advantageous solvent properties that include higher working capacity, lower corrosivity, lower vapor pressure, and lower heat capacity. The phase-changing aminosilicone process has approximately 32% lower equipment capital cost compared to that of the aqueous amine process. However, this solvent is susceptible to thermal degradation at CSTR desorber operating temperatures, which could add as much as $88/tonne to the CO2 capture cost associated with solvent makeup. Future work is focused on mitigating this critical risk by developing an advanced low-temperature desorber that can deliver comparable desorption performance and significantly reduced

  8. Nanostructured transition metal oxides useful for water oxidation catalysis

    Science.gov (United States)

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  9. Water exchange in manganese-based water-oxidizing catalysts in photosynthetic systems: from the water-oxidizing complex in photosystem II to nano-sized manganese oxides.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Isaloo, Mohsen Abbasi; Eaton-Rye, Julian J; Tomo, Tatsuya; Nishihara, Hiroshi; Satoh, Kimiyuki; Carpentier, Robert; Shen, Jian-Ren; Allakhverdiev, Suleyman I

    2014-09-01

    The water-oxidizing complex (WOC), also known as the oxygen-evolving complex (OEC), of photosystem II in oxygenic photosynthetic organisms efficiently catalyzes water oxidation. It is, therefore, responsible for the presence of oxygen in the Earth's atmosphere. The WOC is a manganese-calcium (Mn₄CaO₅(H₂O)₄) cluster housed in a protein complex. In this review, we focus on water exchange chemistry of metal hydrates and discuss the mechanisms and factors affecting this chemical process. Further, water exchange rates for both the biological cofactor and synthetic manganese water splitting are discussed. The importance of fully unveiling the water exchange mechanism to understand the chemistry of water oxidation is also emphasized here. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Bench-scale Development of an Advanced Solid Sorbent-based CO2 Capture Process for Coal-fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Thomas [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Kataria, Atish [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Soukri, Mustapha [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Farmer, Justin [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Mobley, Paul [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Tanthana, Jak [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Wang, Dongxiang [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Wang, Xiaoxing [Research Triangle Institute (RTI), Research Triangle Park, NC (United States); Song, Chunshan [Research Triangle Institute (RTI), Research Triangle Park, NC (United States)

    2015-12-31

    It is increasingly clear that CO2 capture and sequestration (CCS) must play a critical role in curbing worldwide CO2 emissions to the atmosphere. Development of these technologies to cost-effectively remove CO2 from coal-fired power plants is very important to mitigating the impact these power plants have within the world’s power generation portfolio. Currently, conventional CO2 capture technologies, such as aqueous-monoethanolamine based solvent systems, are prohibitively expensive and if implemented could result in a 75 to 100% increase in the cost of electricity for consumers worldwide. Solid sorbent CO2 capture processes – such as RTI’s Advanced Solid Sorbent CO2, Capture Process – are promising alternatives to conventional, liquid solvents. Supported amine sorbents – of the nature RTI has developed – are particularly attractive due to their high CO2 loadings, low heat capacities, reduced corrosivity/volatility and the potential to reduce the regeneration energy needed to carry out CO2 capture. Previous work in this area has failed to adequately address various technology challenges such as sorbent stability and regenerability, sorbent scale-up, improved physical strength and attrition-resistance, proper heat management and temperature control, proper solids handling and circulation control, as well as the proper coupling of process engineering advancements that are tailored for a promising sorbent technology. The remaining challenges for these sorbent processes have provided the framework for the project team’s research and development and target for advancing the technology beyond lab- and bench-scale testing. Under a cooperative agreement with the US Department of Energy, and part of NETL’s CO2 Capture Program, RTI has led an effort to address and mitigate the challenges associated with solid sorbent CO2 capture. The overall objective

  11. Nanostructured manganese oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing composites in artificial photosynthesis.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Rahimi, Fahime; Fathollahzadeh, Maryam; Haghighi, Behzad; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

    2014-07-28

    Herein, we report on nano-sized Mn oxide/carbon nanotubes, graphene and graphene oxide as water-oxidizing compounds in artificial photosynthesis. The composites are synthesized by different and simple procedures and characterized by a number of methods. The water-oxidizing activities of these composites are also considered in the presence of cerium(IV) ammonium nitrate. Some composites are efficient Mn-based catalysts with TOF (mmol O2 per mol Mn per second) ~ 2.6.

  12. Increasing Desalination by Mitigating Anolyte pH Imbalance Using Catholyte Effluent Addition in a Multi-Anode Bench Scale Microbial Desalination Cell

    KAUST Repository

    Davis, Robert J.

    2013-09-03

    A microbial desalination cell (MDC) uses exoelectrogenic bacteria to oxidize organic matter while desalinating water. Protons produced from the oxidation of organics at the anode result in anolyte acidification and reduce performance. A new method was used here to mitigate anolyte acidification based on adding non-buffered saline catholyte effluent from a previous cycle to the anolyte at the beginning of the next cycle. This method was tested using a larger-scale MDC (267 mL) containing four anode brushes and a three cell pair membrane stack. With an anolyte salt concentration increased by an equivalent of 75 mM NaCl using the catholyte effluent, salinity was reduced by 26.0 ± 0.5% (35 g/L NaCl initial solution) in a 10 h cycle, compared to 18.1 ± 2.0% without catholyte addition. This improvement was primarily due to the increase in buffering capacity of the anolyte, although increased conductivity slightly improved performance as well. There was some substrate loss from the anolyte by diffusion into the membrane stack, but this was decreased from 11% to 2.6% by increasing the anolyte conductivity (7.6 to 14 mS/cm). These results demonstrated that catholyte effluent can be utilized as a useful product for mitigating anolyte acidification and improving MDC performance. © 2013 American Chemical Society.

  13. Supramolecular water oxidation with rubda-based catalysts

    KAUST Repository

    Richmond, Craig J.

    2014-11-05

    Extremely slow and extremely fast new water oxidation catalysts based on the Rubda (bda = 2,2′-bipyri-dine-6,6′-dicarboxylate) systems are reported with turnover frequencies in the range of 1 and 900 cycless"1, respectively. Detailed analyses of the main factors involved in the water oxidation reaction have been carried out and are based on a combination of reactivity tests, electrochemical experiments, and DFT calculations. These analyses give a convergent interpretation that generates a solid understanding of the main factors involved in the water oxidation reaction, which in turn allows the design of catalysts with very low energy barriers in all the steps involved in the water oxidation catalytic cycle. We show that for this type of system p-stacking interactions are the key factors that influence reactivity and by adequately controlling them we can generate exceptionally fast water oxidation catalysts.

  14. Bench-Scale Testing and Process Performance Projections of CO2 Capture by CO2–Binding Organic Liquids (CO2BOLs) With and Without Polarity-Swing-Assisted Regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Feng; Heldebrant, David J.; Mathias, Paul M.; Koech, Phillip K.; Bhakta, Mukund; Freeman, Charles J.; Bearden, Mark D.; Zwoster, Andy

    2016-01-12

    This manuscript provides a detailed analysis of a continuous flow, bench scale study of the CO2BOL solvent platform with and without its Polarity Swing Assisted Regeneration (PSAR). This study encompassed four months of continuous flow testing of a candidate CO2BOL with a thermal regeneration and PSAR regeneration using decane antisolvent. In both regeneration schemes, steady state capture of >90 %CO2 was achieved using simulated flue gas at acceptable L/G ratios. Aspen Plus™ modeling was performed to assess process performance compared to previous equilibrium performance projections. This paper also includes net power projections, and comparisons to DOE’s Case 10 amine baseline.

  15. Bench-Scale and Pilot-Scale Treatment Technologies for the Removal of Total Dissolved Solids from Coal Mine Water: A Review.

    Data.gov (United States)

    U.S. Environmental Protection Agency — There is no database. This dataset is not publicly accessible because: This is a review manuscript, there was not data generated under this effort. All data used was...

  16. Water oxidation catalysts and methods of use thereof

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Craig L.; Gueletii, Yurii V.; Musaev, Djamaladdin G.; Yin, Qiushi; Botar, Bogdan

    2017-12-05

    Homogeneous water oxidation catalysts (WOCs) for the oxidation of water to produce hydrogen ions and oxygen, and methods of making and using thereof are described herein. In a preferred embodiment, the WOC is a polyoxometalate WOC which is hydrolytically stable, oxidatively stable, and thermally stable. The WOC oxidized waters in the presence of an oxidant. The oxidant can be generated photochemically, using light, such as sunlight, or electrochemically using a positively biased electrode. The hydrogen ions are subsequently reduced to form hydrogen gas, for example, using a hydrogen evolution catalyst (HEC). The hydrogen gas can be used as a fuel in combustion reactions and/or in hydrogen fuel cells. The catalysts described herein exhibit higher turn over numbers, faster turn over frequencies, and/or higher oxygen yields than prior art catalysts.

  17. Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

    Science.gov (United States)

    Zhang, Zhongguo; Liu, Dan; Qian, Yu; Wu, Yue; He, Peiran; Liang, Shuang; Fu, Xiaozheng; Li, Jiding; Ye, Changqing

    2017-06-01

    A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO 4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO 4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes. Copyright © 2016. Published by Elsevier B.V.

  18. Thin cuprous oxide films prepared by thermal oxidation of copper foils with water vapor

    Energy Technology Data Exchange (ETDEWEB)

    Liang Jianbo, E-mail: liangjienbo1980@yahoo.co.jp [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Kishi, Naoki; Soga, Tetsuo [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan); Jimbo, Takashi [Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya 4668555 (Japan); Ahmed, Mohsin [Department of Frontier Materials,Nagoya Institute of Technology, Nagoya 4668555 (Japan)

    2012-01-31

    We present an improved preparation method for the growth of high quality crystals of cuprous oxide films grown by thermal oxidation of cupper foils with water vapor. This method proved to be good for preparing cuprous oxide films with high purity and large grain size. X-ray diffraction studies revealed the formation of Cu{sub 2}O films with preferred (111) orientation. The cuprous oxide diodes fabricated by the above technique have been studied using current-voltage method.

  19. Water oxidation by amorphous cobalt-based oxides: volume activity and proton transfer to electrolyte bases.

    Science.gov (United States)

    Klingan, Katharina; Ringleb, Franziska; Zaharieva, Ivelina; Heidkamp, Jonathan; Chernev, Petko; Gonzalez-Flores, Diego; Risch, Marcel; Fischer, Anna; Dau, Holger

    2014-05-01

    Water oxidation in the neutral pH regime catalyzed by amorphous transition-metal oxides is of high interest in energy science. Crucial determinants of electrocatalytic activity were investigated for a cobalt-based oxide film electrodeposited at various thicknesses on inert electrodes. For water oxidation at low current densities, the turnover frequency (TOF) per cobalt ion of the bulk material stayed fully constant for variation of the thickness of the oxide film by a factor of 100 (from about 15 nm to 1.5 μm). Thickness variation changed neither the nanostructure of the outer film surface nor the atomic structure of the oxide catalyst significantly. These findings imply catalytic activity of the bulk hydrated oxide material. Nonclassical dependence on pH was observed. For buffered electrolytes with pKa values of the buffer base ranging from 4.7 (acetate) to 10.3 (hydrogen carbonate), the catalytic activity reflected the protonation state of the buffer base in the electrolyte solution directly and not the intrinsic catalytic properties of the oxide itself. It is proposed that catalysis of water oxidation occurs within the bulk hydrated oxide film at the margins of cobalt oxide fragments of molecular dimensions. At high current densities, the availability of a proton-accepting base at the catalyst-electrolyte interface controls the rate of water oxidation. The reported findings may be of general relevance for water oxidation catalyzed at moderate pH by amorphous transition-metal oxides. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Kinetics of zero valent iron nanoparticle oxidation in oxygenated water.

    Science.gov (United States)

    Greenlee, Lauren F; Torrey, Jessica D; Amaro, Robert L; Shaw, Justin M

    2012-12-04

    Zero valent iron (ZVI) nanoparticles are versatile in their ability to remove a wide variety of water contaminants, and ZVI-based bimetallic nanoparticles show increased reactivity above that of ZVI alone. ZVI nanoparticles degrade contaminants through the reactive species (e.g., OH*, H(2(g)), H(2)O(2)) that are produced during iron oxidation. Measurement and modeling of aqueous ZVI nanoparticle oxidation kinetics are therefore necessary to optimize nanoparticle design. Stabilized ZVI and iron-nickel nanoparticles of approximately 150 nm in diameter were synthesized through solution chemistry, and nanoparticle oxidation kinetics were determined via measured mass change using a quartz crystal microbalance (QCM). Under flowing aerated water, ZVI nanoparticles had an initial exponential growth behavior indicating surface-dominated oxidation controlled by migration of species (H(2)O and O(2)) to the surface. A region of logarithmic growth followed the exponential growth which, based on the Mott-Cabrera model of thin oxide film growth, suggests a reaction dominated by movement of species (e.g., iron cations and oxygen anions) through the oxide layer. The presence of ethanol or a nickel shell on the ZVI nanoparticles delayed the onset of iron oxidation and reduced the extent of oxidation. In oxygenated water, ZVI nanoparticles oxidized primarily to the iron oxide-hydroxide lepidocrocite.

  1. Collecting meaningful early-time kinetic data in homogeneous catalytic water oxidation with a sacrificial oxidant.

    Science.gov (United States)

    Vickers, James W; Sumliner, Jordan M; Lv, Hongjin; Morris, Mike; Geletii, Yurii V; Hill, Craig L

    2014-06-28

    As the field of water oxidation catalysis grows, so does the sophistication of the associated experimental apparatuses. However, problems persist in studying some of the most basic aspects of catalytic water oxidation including acquisition of satisfactory early-reaction-time kinetics and rapid quantification of O2 concentration. We seek to remedy these problems and through better experimental design, elucidate mechanistic aspects of catalytic water oxidation with theory backed by experimental data. Two new methods for evaluating homogeneous water oxidation catalysts by reaction with a stoichiometric oxidant are presented which eliminate problems of incomplete fast mixing and O2 measurement response time. These methods generate early-reaction-time kinetics that have previously been unavailable.

  2. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides.

    Science.gov (United States)

    Najafpour, Mohamad Mahdi; Heidari, Sima; Balaghi, S Esmael; Hołyńska, Małgorzata; Sadr, Moayad Hossaini; Soltani, Behzad; Khatamian, Maasoumeh; Larkum, Anthony W; Allakhverdiev, Suleyman I

    2017-02-01

    Plants, algae and cyanobacteria capture sunlight, extracting electrons from H2O to reduce CO2 into sugars while releasing O2 in the oxygenic photosynthetic process. Because of the important role of water oxidation in artificial photosynthesis and many solar fuel systems, understanding the structure and function of this unique biological catalyst forms a requisite research field. Herein the structure of the water-oxidizing complex and its ligand environment are described with reference to the 1.9Å resolution X-ray-derived crystallographic model of the water-oxidizing complex from the cyanobacterium Thermosynechococcus vulcanus. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides are also reviewed and discussed in the paper. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

    DEFF Research Database (Denmark)

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Nørskov, Jens K.

    2015-01-01

    evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates...

  4. Supercritical water oxidation data acquisition testing. Final report, Volume I

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    This report discusses the phase one testing of a data acquisition system for a supercritical water waste oxidation system. The system is designed to destroy a wide range of organic materials in mixed wastes. The design and testing of the MODAR Oxidizer is discussed. An analysis of the optimized runs is included.

  5. Influence of water on the anodic oxidation mechanism of ...

    African Journals Online (AJOL)

    The following successive scans showed a high decrease of the current intensity and that is due to the formation of an insulating coating layer on the electrode surface. When water is added to the non-aqueous electrolyte, a DETA oxidation wave appears on the voltammograms. That oxidation wave is observed on the ...

  6. Process for treating effluent from a supercritical water oxidation reactor

    Science.gov (United States)

    Barnes, Charles M.; Shapiro, Carolyn

    1997-01-01

    A method for treating a gaseous effluent from a supercritical water oxidation reactor containing entrained solids is provided comprising the steps of expanding the gas/solids effluent from a first to a second lower pressure at a temperature at which no liquid condenses; separating the solids from the gas effluent; neutralizing the effluent to remove any acid gases; condensing the effluent; and retaining the purified effluent to the supercritical water oxidation reactor.

  7. Mononuclear and Heterotrinuclear Ruthenium Complexes: Synthesis and Water Oxidation Activity

    OpenAIRE

    Mognon, Lorenzo

    2015-01-01

    Artificial photosynthesis constitutes an intriguing alternative to fossil fuels, and the water oxidation reaction is considered the bottleneck for the achievement of an efficient device to perform it. Extensive research has been carried out, and is still ongoing, to identify the properties and mechanisms that define a good water oxidation catalyst. Ruthenium complexes have shown to be valid candidates for this task. This work presents the synthesis and characterization of multiple mononuclear...

  8. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation.

    Science.gov (United States)

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H; Navrotsky, Alexandra

    2013-05-28

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn(3+)/Mn(4+) ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states.

  9. Sodium periodate as a primary oxidant for water-oxidation catalysts.

    Science.gov (United States)

    Parent, Alexander R; Brewster, Timothy P; De Wolf, Wendy; Crabtree, Robert H; Brudvig, Gary W

    2012-06-04

    Sodium periodate was characterized as a primary chemical oxidant for the catalytic evolution of oxygen at neutral pH using a variety of water-oxidation catalysts. The visible spectra of solutions formed from Cp*Ir(bpy)SO(4) during oxygen-evolution catalysis were measured. NMR spectroscopy suggests that the catalyst remains molecular after several turnovers with sodium periodate. Two of our [Cp*Ir(bis-NHC)][PF(6)](2) complexes, along with other literature catalysts, such as the manganese terpyridyl dimer, Hill's cobalt polyoxometallate, and Meyer's blue dimer, were also tested for activity. Sodium periodate was found to function only for water-oxidation catalysts with low overpotentials. This specificity is attributed to the relatively low oxidizing capability of sodium periodate solutions relative to solutions of other common primary oxidants. Studying oxygen-evolution catalysis by using sodium periodate as a primary oxidant may, therefore, provide preliminary evidence that a given catalyst has a low overpotential.

  10. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

    Science.gov (United States)

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  11. Oxidation and photo-oxidation of water on TiO2 surface

    DEFF Research Database (Denmark)

    Valdes, A.; Qu, Z.W.; Kroes, G.J.

    2008-01-01

    The oxidation and photo-oxidation of water on the rutile TiO2(110) surface is investigated using density functional theory (DFT) calculations. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed for the electrol...

  12. Time-resolved observations of water oxidation intermediates on a cobalt oxide nanoparticle catalyst

    Science.gov (United States)

    Zhang, Miao; de Respinis, Moreno; Frei, Heinz

    2014-04-01

    In any artificial photosynthetic system, the oxidation of water to molecular oxygen provides the electrons needed for the reduction of protons or carbon dioxide to a fuel. Understanding how this four-electron reaction works in detail is important for the development of improved robust catalysts made of Earth-abundant materials, like first-row transition-metal oxides. Here, using time-resolved Fourier-transform infrared spectroscopy and under reaction conditions, we identify intermediates of water oxidation catalysed by an abundant metal-oxide catalyst, cobalt oxide (Co3O4). One intermediate is a surface superoxide (three-electron oxidation intermediate absorbing at 1,013 cm-1), whereas a second observed intermediate is attributed to an oxo Co(IV) site (one-electron oxidation intermediate absorbing at 840 cm-1). The temporal behaviour of the intermediates reveals that they belong to different catalytic sites. Knowledge of the structure and kinetics of surface intermediates will enable the design of improved metal-oxide materials for more efficient water oxidation catalysis.

  13. Dynamic Stabilization of Metal Oxide-Water Interfaces.

    Science.gov (United States)

    McBriarty, Martin E; von Rudorff, Guido Falk; Stubbs, Joanne E; Eng, Peter J; Blumberger, Jochen; Rosso, Kevin M

    2017-02-22

    The interaction of water with metal oxide surfaces plays a crucial role in the catalytic and geochemical behavior of metal oxides. In a vast majority of studies, the interfacial structure is assumed to arise from a relatively static lowest energy configuration of atoms, even at room temperature. Using hematite (α-Fe 2 O 3 ) as a model oxide, we show through a direct comparison of in situ synchrotron X-ray scattering with density functional theory-based molecular dynamics simulations that the structure of the (11̅02) termination is dynamically stabilized by picosecond water exchange. Simulations show frequent exchanges between terminal aquo groups and adsorbed water in locations and with partial residence times consistent with experimentally determined atomic sites and fractional occupancies. Frequent water exchange occurs even for an ultrathin adsorbed water film persisting on the surface under a dry atmosphere. The resulting time-averaged interfacial structure consists of a ridged lateral arrangement of adsorbed water molecules hydrogen bonded to terminal aquo groups. Surface pK a prediction based on bond valence analysis suggests that water exchange will influence the proton-transfer reactions underlying the acid/base reactivity at the interface. Our findings provide important new insights for understanding complex interfacial chemical processes at metal oxide-water interfaces.

  14. Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I

    2012-10-07

    There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese-calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups.

  15. Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I.

    2012-01-01

    There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese–calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. PMID:22809849

  16. Nanostructured manganese oxides as highly active water oxidation catalysts: a boost from manganese precursor chemistry.

    Science.gov (United States)

    Menezes, Prashanth W; Indra, Arindam; Littlewood, Patrick; Schwarze, Michael; Göbel, Caren; Schomäcker, Reinhard; Driess, Matthias

    2014-08-01

    We present a facile synthesis of bioinspired manganese oxides for chemical and photocatalytic water oxidation, starting from a reliable and versatile manganese(II) oxalate single-source precursor (SSP) accessible through an inverse micellar molecular approach. Strikingly, thermal decomposition of the latter precursor in various environments (air, nitrogen, and vacuum) led to the three different mineral phases of bixbyite (Mn2 O3 ), hausmannite (Mn3 O4 ), and manganosite (MnO). Initial chemical water oxidation experiments using ceric ammonium nitrate (CAN) gave the maximum catalytic activity for Mn2 O3 and MnO whereas Mn3 O4 had a limited activity. The substantial increase in the catalytic activity of MnO in chemical water oxidation was demonstrated by the fact that a phase transformation occurs at the surface from nanocrystalline MnO into an amorphous MnOx (1oxidizing agent. Photocatalytic water oxidation in the presence of [Ru(bpy)3 ](2+) (bpy=2,2'-bipyridine) as a sensitizer and peroxodisulfate as an electron acceptor was carried out for all three manganese oxides including the newly formed amorphous MnOx . Both Mn2 O3 and the amorphous MnOx exhibit tremendous enhancement in oxygen evolution during photocatalysis and are much higher in comparison to so far known bioinspired manganese oxides and calcium-manganese oxides. Also, for the first time, a new approach for the representation of activities of water oxidation catalysts has been proposed by determining the amount of accessible manganese centers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hydrothermal Synthesis of Metal Oxide Nanoparticles in Supercritical Water

    Science.gov (United States)

    Hayashi, Hiromichi; Hakuta, Yukiya

    2010-01-01

    This paper summarizes specific features of supercritical hydrothermal synthesis of metal oxide particles. Supercritical water allows control of the crystal phase, morphology, and particle size since the solvent's properties, such as density of water, can be varied with temperature and pressure, both of which can affect the supersaturation and nucleation. In this review, we describe the advantages of fine particle formation using supercritical water and describe which future tasks need to be solved. PMID:28883312

  18. Selective electrochemical generation of hydrogen peroxide from water oxidation

    CERN Document Server

    Viswanathan, Venkatasubramanian; Nørskov, Jens K

    2015-01-01

    Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH$^*$ can be used as a descriptor to screen for selectivity trends between the 2e$^-$ water oxidation to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate hydrogen peroxide evolution. We present a rati...

  19. VUV/UV/Chlorine as an Enhanced Advanced Oxidation Process for Organic Pollutant Removal from Water: Assessment with a Novel Mini-Fluidic VUV/UV Photoreaction System (MVPS).

    Science.gov (United States)

    Li, Mengkai; Qiang, Zhimin; Hou, Pin; Bolton, James R; Qu, Jiuhui; Li, Peng; Wang, Chen

    2016-06-07

    Vacuum ultraviolet (VUV) and ultraviolet (UV)/chlorine processes are regarded as two of many advanced oxidation processes (AOPs). Because of the similar cost of VUV/UV and UV lamps, a combination of VUV and UV/chlorine (i.e., VUV/UV/chlorine) may enhance the removal of organic pollutants in water but without any additional power input. In this paper, a mini-fluidic VUV/UV photoreaction system (MVPS) was developed for bench-scale experiments, which could emit both VUV (185 nm) and UV (254 nm) or solely UV beams with a nearly identical UV photon fluence. The photon fluence rates of UV and VUV output by the MVPS were determined to be 8.88 × 10(-4) and 4.93 × 10(-5) einstein m(-2) s(-1), respectively. The VUV/UV/chlorine process exhibited a strong enhancement concerning the degradation of methylene blue (MB, a model organic pollutant) as compared to the total performance of the VUV/UV and UV/chlorine processes, although the photon fluence of the VUV only accounted for 5.6% of that of the UV. An acidic pH favored MB degradation by the VUV/UV/chlorine process. The synergistic mechanism of the VUV/UV/chlorine process was mainly ascribed to the effective use of (•)OH for pollutant removal through formation of longer-lived secondary radicals (e.g., (•)OCl). This study demonstrates that the new VUV/UV/chlorine process, as an enhanced AOP, can be applied as a highly effective and energy-saving technology for small-scale water and wastewater treatment.

  20. Sonochemical water splitting in the presence of powdered metal oxides.

    Science.gov (United States)

    Morosini, Vincent; Chave, Tony; Virot, Matthieu; Moisy, Philippe; Nikitenko, Sergey I

    2016-03-01

    Kinetics of hydrogen formation was explored as a new chemical dosimeter allowing probing the sonochemical activity of argon-saturated water in the presence of micro- and nano-sized metal oxide particles exhibiting catalytic properties (ThO2, ZrO2, and TiO2). It was shown that the conventional sonochemical dosimeter based on H2O2 formation is hardly applicable in such systems due to catalytic degradation of H2O2 at oxide surface. The study of H2 generation revealed that at low-frequency ultrasound (20 kHz) the sonochemical water splitting is greatly improved for all studied metal oxides. The highest efficiency is observed for relatively large micrometric particles of ThO2 which is assigned to ultrasonically-driven particle fragmentation accompanied by mechanochemical water molecule splitting. The nanosized metal oxides do not exhibit particle size reduction under ultrasonic treatment but nevertheless yield higher quantities of H2. The enhancement of sonochemical water splitting in this case is most probably resulting from better bubble nucleation in heterogeneous systems. At high-frequency ultrasound (362 kHz), the effect of metal oxide particles results in a combination of nucleation and ultrasound attenuation. In contrast to 20 kHz, micrometric particles slowdown the sonolysis of water at 362 kHz due to stronger attenuation of ultrasonic waves while smaller particles show a relatively weak and various directional effects. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Miao [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division; Univ. of California, Berkeley, CA (United States); Frei, Heinz [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division; Univ. of California, Berkeley, CA (United States)

    2017-02-22

    Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. In conclusion, combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

  2. Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates

    Science.gov (United States)

    Zhang, Miao; Frei, Heinz

    2017-05-01

    Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

  3. Treatment of Arsenazo III contaminated heavy water stored at Darlington

    Energy Technology Data Exchange (ETDEWEB)

    Suryanarayan, S.; Husain, A., E-mail: sriram.s@kinectrics.com [Kinectrics Inc., Toronto, Ontario (Canada); Williams, D., E-mail: denny.williams@opg.com [Ontario Power Generation, Darlington Nuclear Generating Station, Bowmanville, Ontario (Canada)

    2010-07-01

    Darlington Nuclear Generating Station (DNGS) has accumulated over 48 drums of chemistry laboratory waste arising from analysis of heavy water (D{sub 2}O). Several organic, including Arsenazo III, and inorganic contaminants present in these drums results in high total organic carbon (TOC) and conductivity. These drums have not been processed due to uncertainties related to clean-up of Arsenazo III contaminated heavy water. This paper provides details of chemical characterization as well as bench scale studies performed to demonstrate the feasibility of treating the downgraded D{sub 2}O to the stringent target specifications of <1 ppm TOC and <0.1mS/m conductivity, required for feed to the Station Upgrading Plant (SUP). Both ionic organic species such as glycolate, acetate and formate as well as neutral organics such as acetone, methanol and ethylene glycol were detected in all the samples. Morpholine and propylene glycol were detected in one sample. Arsenazo III was determined to be not a major contaminant (maximum 8.4 ppm) in these waste drums, compared to the other organic contaminants present. Various unit processes such as pH adjustment, granular activated carbon (GAC), ion exchange resin (IX), UV-peroxide oxidation (UV-H{sub 2}O{sub 2}) treatments, nanofiltration (NF) as well as reverse osmosis (RO) were tested on a bench scale both singly as well as in various combinations to evaluate their ability to achieve the stringent target conductivity and TOC specifications. Among the various bench scale tests evaluated, the successive processing train used at DNGS and consisting of GAC+IX+UV/H{sub 2}O{sub 2}+IX (polishing) unit operations was found to meet target specifications for both conductivity and TOC. Unit processes comprising (GAC+IX) and (RO-double pass + GAC+IX) met conductivity targets but failed to meet TOC specifications. The results of GAC+IX tests clearly emphasize the importance of using low flow rates for successful reduction in both conductivity as

  4. Nanostructured manganese oxide on silica aerogel: a new catalyst toward water oxidation.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Salimi, Saeideh; Madadkhani, Sepideh; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

    2016-12-01

    Herein we report on the synthesis and characterization of nano-sized Mn oxide/silica aerogel with low density as a good catalyst toward water oxidation. The composite was synthesized by a simple and low-cost hydrothermal procedure. In the next step, we studied the composite in the presence of cerium(IV) ammonium nitrate and photo-produced Ru(bpy) 3(3+) as a water-oxidizing catalyst. The low-density composite is a good Mn-based catalyst with turnover frequencies of ~0.3 and 0.5 (mmol O2/(mol Mn·s)) in the presence of Ru(bpy) 3(3+) and cerium(IV) ammonium nitrate, respectively. In addition to the water-oxidizing activities of the composite under different conditions, its self-healing reaction in the presence of cerium(IV) ammonium nitrate was also studied.

  5. Sunlight-induced photochemical decay of oxidants in natural waters: implications in ballast water treatment.

    Science.gov (United States)

    Cooper, William J; Jones, Adam C; Whitehead, Robert F; Zika, Rod G

    2007-05-15

    The transport and discharge of ship ballast water has been recognized as a major vector for the introduction of invasive species. Chemical oxidants, long used in drinking water and wastewater treatment, are alternative treatment methods for the control of invasive species currently being tested for use on ships. One concern when a ballasted vessel arrives in port is the adverse effects of residual oxidant in the treated water. The most common oxidants include chlorine (HOCl/OCl-), bromine (HOBr/OBr-), ozone (03), hydrogen peroxide (H2O2), chlorine dioxide (ClO2), and monochloramine (NH2Cl). The present study was undertaken to evaluate the sunlight-mediated photochemical decomposition of these oxidants. Sunlight photodecomposition was measured at various pH using either distilled water or oligotrophic Gulf Stream water for specific oxidants. For selected oxidants, quantum yields at specific wavelengths were obtained. An environmental photochemical model, GCSOLAR, also provided predictions of the fate (sunlight photolysis half-lives) of HOCI/OCl-, HOBr/OBr-, ClO2, and NH2Cl for two different seasons at latitude 40 degrees and in water with two different concentrations of chromophoric dissolved organic matter. These data are useful in assessing the environmental fate of ballast water treatment oxidants if they were to be discharged in port.

  6. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters.

    Science.gov (United States)

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel M M; Schubert, Carsten J

    2015-09-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes.

  7. Positioning the Water Oxidation Reaction Sites in Plasmonic Photocatalysts.

    Science.gov (United States)

    Wang, Shengyang; Gao, Yuying; Miao, Shu; Liu, Taifeng; Mu, Linchao; Li, Rengui; Fan, Fengtao; Li, Can

    2017-08-30

    Plasmonic photocatalysis, stemming from the effective light absorbance and confinement of surface plasmons, provides a pathway to enhance solar energy conversion. Although the plasmonic hot electrons in water reduction have been extensively studied, exactly how the plasmonic hot holes participate in the water splitting reaction has not yet been well understood. In particular, where the plasmonic hot holes participate in water oxidation is still illusive. Herein, taking Au/TiO2 as a plasmonic photocatalyst prototype, we investigated the plasmonic hot holes involved in water oxidation. The reaction sites are positioned by photodeposition together with element mapping by electron microscopy, while the distribution of holes is probed by surface photovoltage imaging with Kelvin probe force microscopy. We demonstrated that the plasmonic holes are mainly concentrated near the gold-semiconductor interface, which is further identified as the reaction site for plasmonic water oxidation. Density functional theory also corroborates these findings by revealing the promotion role of interfacial structure (Ti-O-Au) for oxygen evolution. Furthermore, the interfacial effect on plasmonic water oxidation is validated by other Au-semiconductor photocatalytic systems (Au/SrTiO3, Au/BaTiO3, etc.).

  8. Methane oxidation coupled to oxygenic photosynthesis in anoxic waters

    Science.gov (United States)

    Milucka, Jana; Kirf, Mathias; Lu, Lu; Krupke, Andreas; Lam, Phyllis; Littmann, Sten; Kuypers, Marcel MM; Schubert, Carsten J

    2015-01-01

    Freshwater lakes represent large methane sources that, in contrast to the Ocean, significantly contribute to non-anthropogenic methane emissions to the atmosphere. Particularly mixed lakes are major methane emitters, while permanently and seasonally stratified lakes with anoxic bottom waters are often characterized by strongly reduced methane emissions. The causes for this reduced methane flux from anoxic lake waters are not fully understood. Here we identified the microorganisms and processes responsible for the near complete consumption of methane in the anoxic waters of a permanently stratified lake, Lago di Cadagno. Interestingly, known anaerobic methanotrophs could not be detected in these waters. Instead, we found abundant gamma-proteobacterial aerobic methane-oxidizing bacteria active in the anoxic waters. In vitro incubations revealed that, among all the tested potential electron acceptors, only the addition of oxygen enhanced the rates of methane oxidation. An equally pronounced stimulation was also observed when the anoxic water samples were incubated in the light. Our combined results from molecular, biogeochemical and single-cell analyses indicate that methane removal at the anoxic chemocline of Lago di Cadagno is due to true aerobic oxidation of methane fuelled by in situ oxygen production by photosynthetic algae. A similar mechanism could be active in seasonally stratified lakes and marine basins such as the Black Sea, where light penetrates to the anoxic chemocline. Given the widespread occurrence of seasonally stratified anoxic lakes, aerobic methane oxidation coupled to oxygenic photosynthesis might have an important but so far neglected role in methane emissions from lakes. PMID:25679533

  9. Effect of Magnesium Oxide Nanoparticles on Water Glass Structure

    Directory of Open Access Journals (Sweden)

    Bobrowski A.

    2012-09-01

    Full Text Available An attempt has been made to determine the effect of an addition of colloidal suspensions of the nanoparticles of magnesium oxide on the structure of water glass, which is a binder for moulding and core sands. Nanoparticles of magnesium oxide MgO in propanol and ethanol were introduced in the same mass content (5wt.% and structural changes were determined by measurement of the FT-IR absorption spectra.

  10. Destruction of Navy Hazardous Wastes by Supercritical Water Oxidation

    Science.gov (United States)

    1994-08-01

    polychlorinated byphenyls (PCBs) are "one time only" wastes generated by electrical transformer changeout. PCBs are readily destroyed by the SCWO process...sensor on the gaseous effluent discharge line generates an electrical signal that is a measure of SCWO system pressure. The measured pressure is compared...oxidation ( SCWO ) to destroy organic hazardous wastes generated by Navy industrial activities. Supercritical water oxidation is the low temperature

  11. Wet oxidation processes for water pollution remediation

    OpenAIRE

    García Molina, Verónica

    2006-01-01

    The main objective of this work was to test the efficiency of wet oxidation processes when treating several types of aqueous wastes. On one side its performance for the abatement of chloro-organic aromatic toxic pollutants, such as 4-chlorophenol and 2,4-dichlorophenol has been studied. On the other hand, wastewater from pulp and paper mills, which has been reported to be an indirect source of entry of chlorophenols in the aquatic environment, has been investigated. More in detail, it has bee...

  12. Doping-Promoted Solar Water Oxidation on Hematite Photoanodes.

    Science.gov (United States)

    Zhang, Yuchao; Ji, Hongwei; Ma, Wanhong; Chen, Chuncheng; Song, Wenjing; Zhao, Jincai

    2016-07-01

    As one of the most promising materials for solar water oxidation, hematite has attracted intense research interest for four decades. Despite their desirable optical band gap, stability and other attractive features, there are great challenges for the implementation of hematite-based photoelectrochemical cells. In particular, the extremely low electron mobility leads to severe energy loss by electron hole recombination. Elemental doping, i.e., replacing lattice iron with foreign atoms, has been shown to be a practical solution. Here we review the significant progresses in metal and non-metal element doping-promoted hematite solar water oxidation, focusing on the role of dopants in adjusting carrier density, charge collection efficiency and surface water oxidation kinetics. The advantages and salient features of the different doping categories are compared and discussed.

  13. Subcritical and supercritical water oxidation of CELSS model wastes

    Science.gov (United States)

    Takahashi, Y.; Wydeven, T.; Koo, C.

    1989-01-01

    A mixture of ammonium hydroxide with acetic acid and a slurry of human feces, urine, and wipes were used as CELSS model wastes to be wet-oxidized at temperatures from 250 to 500 C, i.e. below and above the critical point of water (374 C and 218 kg/sq cm or 21.4 MPa). The effects of oxidation temperature ( 250-500 C) and residence time (0-120 mn) on carbon and nitrogen and on metal corrosion from the reactor material were studied. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 C, above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. A substantial amount of nitrogen remained in solution in the form of ammonia at temperatures ranging from 350 to 450 C suggesting that, around 400 C, organic carbon is completely oxidized and most of the nitrogen is retained in solution. The Hastelloy C-276 alloy reactor corroded during subcritical and supercritical water oxidation.

  14. Dynamic Stabilization of Metal Oxide-Water Interfaces

    OpenAIRE

    McBriarty, M. E.; von Rudorff, G. F.; Stubbs, J. E.; Eng, P. J.; Blumberger, J.; Ross, K. M.

    2017-01-01

    The interaction of water with metal oxide surfaces plays a crucial role in the catalytic and geochemical behavior of metal oxides. In a vast majority of studies, the interfacial structure is assumed to arise from a relatively static lowest energy configuration of atoms, even at room temperature. Using hematite (α-Fe2O3) as a model oxide, we show through a direct comparison of in situ synchrotron X-ray scattering with density functional theory-based molecular dynamics simulations that the stru...

  15. Electrochemical decontamination of waters by advanced oxidation

    African Journals Online (AJOL)

    a

    chronoamperometry and bulk electrolysis to give the optimization characteristics of the degradation of such a ... the degradation process is perfectly predicted by a theoretical mathematical model. HPLC and. GC-MS ... aqueous solutions by batch electrolysis in the potential region of water decomposition (2.3 V vs. SHE) in ...

  16. BACTERICIDAL ACTIVITY OF ELECTROLYZED OXIDIZING WATER ON MEAT AND POULTRY

    Directory of Open Access Journals (Sweden)

    A. Serraino

    2008-09-01

    Full Text Available Electrolyzed oxidizing water (EOW has potential application as a residue free sanitizing agent for food of animal origin. Meat and poultry were contaminated with microorganism, pathogens or not, and different types of electrolyzed oxidizing water treatement were investigated to evaluate the activity of each of these method. In detail, this study is aiming at evaluating the effectiveness of EOW in reducing microbial count, including total bacterial count, Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes and Escherichia coli on meat and poultry. EOW has a very strong disinfectant activity which, along with its easy and safe use, makes a good alternative to many other more widely used disinfectants.

  17. Supercritical water oxidation - Concept analysis for evolutionary Space Station application

    Science.gov (United States)

    Hall, John B., Jr.; Brewer, Dana A.

    1986-01-01

    The ability of a supercritical water oxidation (SCWO) concept to reduce the number of processes needed in an evolutionary Space Station design's Environmental Control and Life Support System (ECLSS), while reducing resupply requirements and enhancing the integration of separate ECLSS functions into a single Supercritical Water Oxidation process, is evaluated. While not feasible for an initial operational capability Space Station, the SCWO's application to the evolutionary Space Station configuration would aid the integration of eight ECLSS functions into a single one, thereby significantly reducing program costs.

  18. Electrosynthesis of highly transparent cobalt oxide water oxidation catalyst films from cobalt aminopolycarboxylate complexes.

    Science.gov (United States)

    Bonke, Shannon A; Wiechen, Mathias; Hocking, Rosalie K; Fang, Xi-Ya; Lupton, David W; MacFarlane, Douglas R; Spiccia, Leone

    2015-04-24

    Efficient catalysis of water oxidation represents one of the major challenges en route to efficient sunlight-driven water splitting. Cobalt oxides (CoOx ) have been widely investigated as water oxidation catalysts, although the incorporation of these materials into photoelectrochemical devices has been hindered by a lack of transparency. Herein, the electrosynthesis of transparent CoOx catalyst films is described by utilizing cobalt(II) aminopolycarboxylate complexes as precursors to the oxide. These complexes allow control over the deposition rate and morphology to enable the production of thin, catalytic CoOx films on a conductive substrate, which can be exploited in integrated photoelectrochemical devices. Notably, under a bias of 1.0 V (vs. Ag/AgCl), the film deposited from [Co(NTA)(OH2 )2 ](-) (NTA=nitrilotriacetate) decreased the transmission by only 10 % at λ=500 nm, but still generated >80 % of the water oxidation current produced by a [Co(OH2 )6 ](2+) -derived oxide film whose transmission was only 40 % at λ=500 nm. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Uncovering structure-activity relationships in manganese-oxide-based heterogeneous catalysts for efficient water oxidation.

    Science.gov (United States)

    Indra, Arindam; Menezes, Prashanth W; Driess, Matthias

    2015-03-01

    Artificial photosynthesis by harvesting solar light into chemical energy could solve the problems of energy conversion and storage in a sustainable way. In nature, CO2 and H2 O are transformed into carbohydrates by photosynthesis to store the solar energy in chemical bonds and water is oxidized to O2 in the oxygen-evolving center (OEC) of photosystem II (PS II). The OEC contains CaMn4 O5 cluster in which the metals are interconnected through oxido bridges. Inspired by biological systems, manganese-oxide-based catalysts have been synthesized and explored for water oxidation. Structural, functional modeling, and design of the materials have prevailed over the years to achieve an effective and stable catalyst system for water oxidation. Structural flexibility with eg(1) configuration of Mn(III) , mixed valency in manganese, and higher surface area are the main requirements to attain higher efficiency. This Minireview discusses the most recent progress in heterogeneous manganese-oxide-based catalysts for efficient chemical, photochemical, and electrochemical water oxidation as well as the structural requirements for the catalyst to perform actively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The structure of graphene oxide membranes in liquid water, ethanol and water-ethanol mixtures.

    Science.gov (United States)

    Talyzin, Alexandr V; Hausmaninger, Tomas; You, Shujie; Szabó, Tamás

    2014-01-07

    The structure of graphene oxide (GO) membranes was studied in situ in liquid solvents using synchrotron radiation X-ray diffraction in a broad temperature interval. GO membranes are hydrated by water similarly to precursor graphite oxide powders but intercalation of alcohols is strongly hindered, which explains why the GO membranes are permeated by water and not by ethanol. Insertion of ethanol into the membrane structure is limited to only one monolayer in the whole studied temperature range, in contrast to precursor graphite oxide powders, which are intercalated with up to two ethanol monolayers (Brodie) and four ethanol monolayers (Hummers). As a result, GO membranes demonstrate the absence of "negative thermal expansion" and phase transitions connected to insertion/de-insertion of alcohols upon temperature variations reported earlier for graphite oxide powders. Therefore, GO membranes are a distinct type of material with unique solvation properties compared to parent graphite oxides even if they are composed of the same graphene oxide flakes.

  1. Extraction of steviol glycosides from fresh Stevia using acidified water; comparison to hot water extraction, including purification

    NARCIS (Netherlands)

    Kootstra, A.M.J.; Huurman, Sander

    2017-01-01

    This report describes a practical comparison of an acidified water extraction of freshly harvested Stevia
    plants (the NewFoss method) to the hot water extraction of dried Stevia plants, the industry standard. Both
    extracts are subsequently purified using lab-/bench scale standard industrial

  2. Biomimetic metal oxides for the extraction of nanoparticles from water.

    Science.gov (United States)

    Mallampati, Ramakrishna; Valiyaveettil, Suresh

    2013-04-21

    Contamination of nanomaterials in the environment will pose significant health risks in the future. A viable purification method is necessary to address this problem. Here we report the synthesis and application of a series of metal oxides prepared using a biological template for the removal of nanoparticles from the aqueous environment. A simple synthesis of metal oxides such as ZnO, NiO, CuO, Co3O4 and CeO2 employing eggshell membrane (ESM) as a biotemplate is reported. The morphology of the metal oxide powders was characterized using electron microscopes and the lattice structure was established using X-ray diffraction methods. Extraction of nanoparticles from water was carried out to compare the efficiency of metal oxides. NiO showed good extraction efficiency in removing gold and silver nanoparticles from spiked water samples within an hour. Easy access and enhanced stability of metal oxides makes them interesting candidates for applications in industrial effluent treatments and water purifications.

  3. Metal oxide nanostructures by a simple hot water treatment.

    Science.gov (United States)

    Saadi, Nawzat S; Hassan, Laylan B; Karabacak, Tansel

    2017-08-02

    Surfaces with metal oxide nanostructures have gained considerable interest in applications such as sensors, detectors, energy harvesting cells, and batteries. However, conventional fabrication techniques suffer from challenges that hinder wide and effective applications of such surfaces. Most of the metal oxide nanostructure synthesis methods are costly, complicated, non-scalable, environmentally hazardous, or applicable to only certain few materials. Therefore, it is crucial to develop a simple metal oxide nanostructure fabrication method that can overcome all these limitations and pave the way to the industrial application of such surfaces. Here, we demonstrate that a wide variety of metals can form metal oxide nanostructures on their surfaces after simply interacting with hot water. This method, what we call hot water treatment, offers the ability to grow metal oxide nanostructures on most of the metals in the periodic table, their compounds, or alloys by a one-step, scalable, low-cost, and eco-friendly process. In addition, our findings reveal that a "plugging" mechanism along with surface diffusion is critical in the formation of such nanostructures. This work is believed to be of importance especially for researchers working on the growth of metal oxide nanostructures and their application in functional devices.

  4. Does oxidation affect the water functionality of myofibrillar proteins?

    Science.gov (United States)

    Bertram, Hanne Christine; Kristensen, Mette; Østdal, Henrik; Baron, Caroline P; Young, Jette F; Andersen, Henrik Jørgen

    2007-03-21

    Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.

  5. Photochemical water oxidation by crystalline polymorphs of manganese oxides: structural requirements for catalysis.

    Science.gov (United States)

    Robinson, David M; Go, Yong Bok; Mui, Michelle; Gardner, Graeme; Zhang, Zhijuan; Mastrogiovanni, Daniel; Garfunkel, Eric; Li, Jing; Greenblatt, Martha; Dismukes, G Charles

    2013-03-06

    Manganese oxides occur naturally as minerals in at least 30 different crystal structures, providing a rigorous test system to explore the significance of atomic positions on the catalytic efficiency of water oxidation. In this study, we chose to systematically compare eight synthetic oxide structures containing Mn(III) and Mn(IV) only, with particular emphasis on the five known structural polymorphs of MnO2. We have adapted literature synthesis methods to obtain pure polymorphs and validated their homogeneity and crystallinity by powder X-ray diffraction and both transmission and scanning electron microscopies. Measurement of water oxidation rate by oxygen evolution in aqueous solution was conducted with dispersed nanoparticulate manganese oxides and a standard ruthenium dye photo-oxidant system. No Ru was absorbed on the catalyst surface as observed by XPS and EDX. The post reaction atomic structure was completely preserved with no amorphization, as observed by HRTEM. Catalytic activities, normalized to surface area (BET), decrease in the series Mn2O3 > Mn3O4 ≫ λ-MnO2, where the latter is derived from spinel LiMn2O4 following partial Li(+) removal. No catalytic activity is observed from LiMn2O4 and four of the MnO2 polymorphs, in contrast to some literature reports with polydispersed manganese oxides and electro-deposited films. Catalytic activity within the eight examined Mn oxides was found exclusively for (distorted) cubic phases, Mn2O3 (bixbyite), Mn3O4 (hausmannite), and λ-MnO2 (spinel), all containing Mn(III) possessing longer Mn-O bonds between edge-sharing MnO6 octahedra. Electronically degenerate Mn(III) has antibonding electronic configuration e(g)(1) which imparts lattice distortions due to the Jahn-Teller effect that are hypothesized to contribute to structural flexibility important for catalytic turnover in water oxidation at the surface.

  6. Phenol oxidation kinetics in water solution using iron(3)-oxide-based nano-catalysts.

    Science.gov (United States)

    Zelmanov, Grigory; Semiat, Raphael

    2008-08-01

    The influence of inorganic ions (HCO(3), PO(4)/HPO(4)/H(2)PO(4), Cl, SO(4), Ca, Na and Mg) on the advanced chemical oxidation process of organic compounds dissolved in water is reported here. The catalytic behavior of iron(3)-oxide-based nano-particles was investigated together with inorganic ions and hydrogen peroxide concentrations, and pH level. Phenol was chosen as a typical organic contaminant for this study as a simulating pollutant. The limiting concentrations of radical scavengers making the oxidation process inefficient were identified. The strong effect of concentration of radical scavengers HCO(3), PO(4)/HPO(4)/H(2)PO(4), the nano-catalyst and hydrogen peroxide concentrations, and pH on the phenol oxidation rate and lag time period before reaction starts was determined. It was shown that Cl, SO(4), Ca, Na and Mg ions had no significant effect on the kinetics of phenol oxidation.

  7. Oxidation of white phosphorus by peroxides in water

    Science.gov (United States)

    Abdreimova, R. R.; Akbaeva, D. N.; Polimbetova, G. S.

    2017-10-01

    A mixture of hypophosphorous, phosphorous, and phosphoric acids is formed during the anaerobic oxidation of white phosphorus by peroxides [ROOH; R = H, 3-ClC6H4CO, (CH3)3C] in water. The rate of reactions grows considerably upon adding nonpolar organic solvents. The activity series of peroxides and solvents are determined experimentally. NMR spectroscopy shows that the main product of the reaction is phosphorous acid, regardless of the nature of the peroxide and solvent. A radical mechanism of oxidation of white phosphorus by peroxides in water is proposed. It is initiated by the homolysis of peroxide with the formation of HO• radicals that are responsible for the homolytic opening of phosphoric tetrahedrons. Further oxidation and stages of the hydrolysis of intermediate phosphorus-containing compounds yield products of the reaction.

  8. SUPERCRITICAL WATER OXIDATION MODEL DEVELOPMENT FOR SELECTED EPA PRIORITY POLLUTANTS

    Science.gov (United States)

    Supercritical Water Oxidation (SCWO) evaluated for five compounds: acetic acid, 2,4-dichlorophenol, pentachlorophenol, pyridine, 2,4-dichlorophenoxyacetic acid (methyl ester). inetic models were developed for acetic acid, 2,4-dichlorophenol, and pyridine. he test compounds were e...

  9. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  10. Alternating electron and proton transfer steps in photosynthetic water oxidation.

    Science.gov (United States)

    Klauss, André; Haumann, Michael; Dau, Holger

    2012-10-02

    Water oxidation by cyanobacteria, algae, and plants is pivotal in oxygenic photosynthesis, the process that powers life on Earth, and is the paradigm for engineering solar fuel-production systems. Each complete reaction cycle of photosynthetic water oxidation requires the removal of four electrons and four protons from the catalytic site, a manganese-calcium complex and its protein environment in photosystem II. In time-resolved photothermal beam deflection experiments, we monitored apparent volume changes of the photosystem II protein associated with charge creation by light-induced electron transfer (contraction) and charge-compensating proton relocation (expansion). Two previously invisible proton removal steps were detected, thereby filling two gaps in the basic reaction-cycle model of photosynthetic water oxidation. In the S(2) → S(3) transition of the classical S-state cycle, an intermediate is formed by deprotonation clearly before electron transfer to the oxidant (Y Z OX). The rate-determining elementary step (τ, approximately 30 µs at 20 °C) in the long-distance proton relocation toward the protein-water interface is characterized by a high activation energy (E(a) = 0.46 ± 0.05 eV) and strong H/D kinetic isotope effect (approximately 6). The characteristics of a proton transfer step during the S(0) → S(1) transition are similar (τ, approximately 100 µs; E(a) = 0.34 ± 0.08 eV; kinetic isotope effect, approximately 3); however, the proton removal from the Mn complex proceeds after electron transfer to . By discovery of the transient formation of two further intermediate states in the reaction cycle of photosynthetic water oxidation, a temporal sequence of strictly alternating removal of electrons and protons from the catalytic site is established.

  11. Copper-Intercalated Birnessite as a Water Oxidation Catalyst.

    Science.gov (United States)

    Thenuwara, Akila C; Shumlas, Samantha L; Attanayake, Nuwan H; Cerkez, Elizabeth B; McKendry, Ian G; Frazer, Laszlo; Borguet, Eric; Kang, Qing; Zdilla, Michael J; Sun, Jianwei; Strongin, Daniel R

    2015-11-24

    We report a synthetic method to increase the catalytic activity of birnessite toward water oxidation by intercalating copper in the interlayer region of the layered manganese oxide. Intercalation of copper, verified by XRD, XPS, ICP, and Raman spectroscopy, was accomplished by exposing a suspension of birnessite to a Cu(+)-bearing precursor molecule that underwent disproportionation in solution to yield Cu(0) and Cu(2+). Electrocatalytic studies showed that the Cu-modified birnessite exhibited an overpotential for water oxidation of ∼490 mV (at 10 mA/cm(2)) and a Tafel slope of 126 mV/decade compared to ∼700 mV (at 10 mA/cm(2)) and 240 mV/decade, respectively, for birnessite without copper. Impedance spectroscopy results suggested that the charge transfer resistivity of the Cu-modified sample was significantly lower than Cu-free birnessite, suggesting that Cu in the interlayer increased the conductivity of birnessite leading to an enhancement of water oxidation kinetics. Density functional theory calculations show that the intercalation of Cu(0) into a layered MnO2 model structure led to a change of the electronic properties of the material from a semiconductor to a metallic-like structure. This conclusion from computation is in general agreement with the aforementioned impedance spectroscopy results. X-ray photoelectron spectroscopy (XPS) showed that Cu(0) coexisted with Cu(2+) in the prepared Cu-modified birnessite. Control experiments using birnessite that was decorated with only Cu(2+) showed a reduction in water oxidation kinetics, further emphasizing the importance of Cu(0) for the increased activity of birnessite. The introduction of Cu(0) into the birnessite structure also increased the stability of the electrocatalyst. At a working current of 2 mA, the Cu-modified birnessite took ∼3 times longer for the overpotential for water oxdiation to increase by 100 mV compared to when Cu was not present in the birnessite.

  12. In Vitro and In Vivo Evaluation of Amorphous Solid Dispersions Generated by Different Bench-Scale Processes, Using Griseofulvin as a Model Compound

    OpenAIRE

    Chiang, Po-Chang; Cui, Yong; Ran, Yingqing; Lubach, Joe; Chou, Kang-Jye; Bao, Linda; Jia, Wei; La, Hank; Hau, Jonathan; Sambrone, Amy; Qin, Ann; Deng, Yuzhong; Wong, Harvey

    2013-01-01

    Drug polymer-based amorphous solid dispersions (ASD) are widely used in the pharmaceutical industry to improve bioavailability for poorly water-soluble compounds. Spray-drying is the most common process involved in the manufacturing of ASD material. However, spray-drying involves a high investment of material quantity and time. Lower investment manufacturing processes such as fast evaporation and freeze-drying (lyophilization) have been developed to manufacture ASD at the bench level. The gen...

  13. Water-mediated proton hopping on an iron oxide surface.

    Science.gov (United States)

    Merte, Lindsay R; Peng, Guowen; Bechstein, Ralf; Rieboldt, Felix; Farberow, Carrie A; Grabow, Lars C; Kudernatsch, Wilhelmine; Wendt, Stefan; Lægsgaard, Erik; Mavrikakis, Manos; Besenbacher, Flemming

    2012-05-18

    The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H(3)O(+)-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO(2)(110), where water dissociation is a key step in proton diffusion.

  14. Artificial photosynthesis challenges: water oxidation at nanostructured interfaces.

    Science.gov (United States)

    Carraro, Mauro; Sartorel, Andrea; Toma, Francesca Maria; Puntoriero, Fausto; Scandola, Franco; Campagna, Sebastiano; Prato, Maurizio; Bonchio, Marcella

    2011-01-01

    Innovative oxygen evolving catalysts, taken from the pool of nanosized, water soluble, molecular metal oxides, the so-called polyoxometalates (POMs), represent an extraordinary opportunity in the field of artificial photosynthesis. These catalysts possess a highly robust, totally inorganic structure, and can provide a unique mimicry of the oxygen evolving center in photosynthetic II enzymes. As a result POMs can effect H₂O oxidation to O₂ with unprecedented efficiency. In particular, the tetra-ruthenium based POM [Ru(IV) ₄(μ-OH)₂(μ-O)₄(H₂O)₄(γ-SiW(10)O(36))₂](10-), Ru₄(POM), displays fast kinetics, electrocatalytic activity powered by carbon nanotubes and exceptionally light-driven performance. A broad perspective is presented herein by addressing the recent progress in the field of metal-oxide nano-clusters as water oxidation catalysts, including colloidal species. Moreover, the shaping of the catalyst environment plays a fundamental role by alleviating the catalyst fatigue and stabilizing competent intermediates, thus responding to what are the formidable thermodynamic and kinetic challenges of water splitting. The design of nano-interfaces with specifically tailored carbon nanostructures and/or polymeric scaffolds opens a vast scenario for tuning electron/proton transfer mechanisms. Therefore innovation is envisaged based on the molecular modification of the hybrid photocatalytic center and of its environment.

  15. Highly water-soluble multi-walled carbon nanotubes amine-functionalized by supercritical water oxidation.

    Science.gov (United States)

    Chun, Kyoung-Yong; Moon, In-Kyu; Han, Joo-Hee; Do, Seung-Hoe; Lee, Jin-Seo; Jeon, Seong-Yun

    2013-11-07

    Multi-walled carbon nanotubes (MWNTs) have been amine-functionalized by eco-friendly supercritical water oxidation. The facilely functionalized MWNTs have high solubility (~84 mg L(-1)) in water and 78% transmittance at 30-fold dilution. The Tyndall effect is also shown for several liquids.

  16. MERCURY OXIDATION PROMOTED BY A SELECTIVE CATALYTIC REDUCTION CATALYST UNDER SIMULATED POWDER RIVER BASIN COAL COMBUSTION CONDITIONS

    Science.gov (United States)

    A bench-scale reactor consisting of a natural gas burner and an electrically heated reactor housing a selective catalytic reduction (SCR) catalyst was constructed for studying elemental mercury oxidation under SCR conditions. A low sulfur Power River Basin (PRB) coal combustion ...

  17. Oxidative gating of water channels (aquaporins) in corn roots.

    Science.gov (United States)

    Ye, Qing; Steudle, Ernst

    2006-04-01

    An oxidative gating of water channels (aquaporins: AQPs) was observed in roots of corn seedlings as already found for the green alga Chara corallina. In the presence of 35 mM hydrogen peroxide (H2O2)--a precursor of hydroxyl radicals (*OH)--half times of water flow (as measured with the aid of pressure probes) increased at the level of both entire roots and individual cortical cells by factors of three and nine, respectively. This indicated decreases in the hydrostatic hydraulic conductivity of roots (Lp(hr)) and of cells (Lp(h)) by the same factors. Unlike other stresses, the plant hormone abscisic acid (ABA) had no ameliorative effect either on root LP(hr) or on cell Lp(h) when AQPs were inhibited by oxidative stress. Closure of AQPs reduced the permeability of acetone by factors of two in roots and 1.5 in cells. This indicated that AQPs were not ideally selective for water but allowed the passage of the organic solute acetone. In the presence of H2O2, channel closure caused anomalous (negative) osmosis at both the root and the cell level. This was interpreted by the fact that in the case of the rapidly permeating solute acetone, channel closure caused the solute to move faster than the water and the reflection coefficient (sigma s) reversed its sign. When H2O2 was removed from the medium, the effects were reversible, again at both the root and the cell level. The results provide evidence of oxidative gating of AQPs, which leads on to inhibition of water uptake by the roots. Possible mechanisms of the oxidative gating of AQPs induced by H2O2 (*OH) are discussed.

  18. Bench-Scale Study of Hydrogen Separation Using Pre-Commercial Membranes; Estudio, a Escala de Planta Piloto, del Proceso de Separacion de Hidrogeno mediante Membranas Pre-Comerciales

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Hervas, J. M.; Marano, M.

    2011-11-10

    This report compiles the research undertaken by CIEMAT over 2009-2011 in the sub-project 8 Purification and Separation of Hydrogen of the PSE H2ENOV Project funded by the Spanish Ministry of Science and Innovation, MICINN. Permeability and hydrogen selectivity of a pre-commercial palladium membrane was studied at bench scale level. The effect of main operating parameters - pressure, temperature and feed-flow-rate- on permeate flow-rate was determined. The influence of other gas components on hydrogen permeation was evaluated. Mixtures of H{sub 2}-N{sub 2} and H{sub 2}-CO{sub 2} were studied. Although nitrogen and carbon dioxide did not permeate, both components decreased hydrogen permeation rate. Operating the membrane for around 1000 h under various conditions showed a small decrease in hydrogen permeation, but not in selectivity. A literature review was done in order to identify causes for permeation inhibition and reduction and for the definition of procedures for membrane regeneration. (Author) 29 refs.

  19. In vitro and in vivo evaluation of amorphous solid dispersions generated by different bench-scale processes, using griseofulvin as a model compound.

    Science.gov (United States)

    Chiang, Po-Chang; Cui, Yong; Ran, Yingqing; Lubach, Joe; Chou, Kang-Jye; Bao, Linda; Jia, Wei; La, Hank; Hau, Jonathan; Sambrone, Amy; Qin, Ann; Deng, Yuzhong; Wong, Harvey

    2013-04-01

    Drug polymer-based amorphous solid dispersions (ASD) are widely used in the pharmaceutical industry to improve bioavailability for poorly water-soluble compounds. Spray-drying is the most common process involved in the manufacturing of ASD material. However, spray-drying involves a high investment of material quantity and time. Lower investment manufacturing processes such as fast evaporation and freeze-drying (lyophilization) have been developed to manufacture ASD at the bench level. The general belief is that the overall performance of ASD material is thermodynamically driven and should be independent of the manufacturing process. However, no formal comparison has been made to assess the in vivo performance of material generated by different processes. This study compares the in vitro and in vivo properties of ASD material generated by fast evaporation, lyophilization, and spray-drying methods using griseofulvin as a model compound and hydroxypropyl methylcellulose acetate succinate as the polymer matrix. Our data suggest that despite minor differences in the formulation release properties and stability of the ASD materials, the overall exposure is comparable between the three manufacturing processes under the conditions examined. These results suggest that fast evaporation and lyophilization may be suitable to generate ASD material for oral evaluation. However, caution should be exercised since the general applicability of the present findings will need to be further evaluated.

  20. Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2002-02-27

    During the development of a standard for the safe, long-term storage of {sup 233}U-containing materials, several areas were identified that needed additional experimental studies. These studies were related to the perceived potential for the radiolytic generation of large pressures or explosive concentrations of gases in storage containers. This report documents the results of studies on the sorption of water by various uranium oxides and on the gamma radiolysis of uranium oxides containing various amounts of sorbed moisture. In all of the experiments, {sup 238}U was used as a surrogate for the {sup 233}U. For the water sorption experiments, uranium oxide samples were prepared and exposed to known levels of humidity to establish the water uptake rate. Subsequently, the amount of water removed was studied by heating samples in a oven at fixed temperatures and by thermogravimetric analysis (TGA)/differential thermal analysis (DTA). It was demonstrated that heating at 650 C adequately removes all moisture from the samples. Uranium-238 oxides were irradiated in a {sup 60}Co source and in the high-gamma-radiation fields provided by spent nuclear fuel elements of the High Flux Isotope Reactor. For hydrated samples of UO{sub 3}, H{sub 2} was the primary gas produced; but the total gas pressure increase reached steady value of about 10 psi. This production appears to be a function of the dose and the amount of water present. Oxygen in the hydrated UO{sub 3} sample atmosphere was typically depleted, and no significant pressure rise was observed. Heat treatment of the UO{sub 3} {center_dot} xH{sub 2}O at 650 C would result in conversion to U{sub 3}O{sub 8} and eliminate the H{sub 2} production. For all of the U{sub 3}O{sub 8} samples loaded in air and irradiated with gamma radiation, a pressure decrease was seen and little, if any, H{sub 2} was produced--even for samples with up to 9 wt % moisture content. Hence, these results demonstrated that the efforts to remove trace

  1. Water defluoridation with activated aluminum oxide A-1

    Energy Technology Data Exchange (ETDEWEB)

    Berendeeva, V.L.; Vakhnin, I.G.; Goronovskiy, I.T.

    A column approach was used to define the actors affecting the efficiency of aluminum oxide A-1 columns in defluoridation of drinking water. The data showed that the adsorptive capacity of A-1 for the bicarbonate ion was greater than for F/sup -/ and that, therefore, the bicarbonate ion interfered with the elimination of F/sup -/. In order to increase the efficiency and adsorptivity for F/sup -/, the water pH should be adjusted to 4-5. In model systems with NaF in distilled water the adsorptive capacity for F/sup -/ was determined as 3800 g/m/sup 3/ of A-1, and for tap water containing the bicarbonate ion the adsorptivity was calculated as 900 g/m/sup 3/ of A-1. 5 references, 1 figure.

  2. Electrochemical Oxidation of PAHs in Water from Harbor Sediment Purification

    DEFF Research Database (Denmark)

    Muff, Jens; Søgaard, Erik Gydesen

    to contamination by PAH, heavy metals, TBT etc. In Denmark, contaminated harbor sediment is pumped ashore to inland lakes or upland sites where treatment of the runoff water is required before discharge to the recipient. In this study, electrochemical oxidation (EO) has been investigated as a method for treatment...... of the discharge water addressing primarily polycyclic aromatic hydrocarbons (PAHs). PAHs are by-products of incomplete combustion of organic materials with recalcitrant and strong mutagenic/carcinogenic properties, due to their benzene analogue structures. PAHs are hydrophobic compounds and their persistence...... in the environment is mainly due to their low water solubility. The experimental study was performed in laboratory scale with volumes of water from 3 to 10 L in a batch recirculation experimental setup at constant temperature with a commercial one-compartment cell of tubular design with Ti/Pt90-Ir10 anode (60 cm2...

  3. Water-oxidation catalysis by synthetic manganese oxides--systematic variations of the calcium birnessite theme.

    Science.gov (United States)

    Frey, Carolin E; Wiechen, Mathias; Kurz, Philipp

    2014-03-21

    Layered manganese oxides from the birnessite mineral family have been identified as promising heterogeneous compounds for water-oxidation catalysis (WOC), a key reaction for the conversion of renewable energy into storable fuels. High catalytic rates were especially observed for birnessites which contain calcium as part of their structures. With the aim to systematically improve the catalytic performance of such oxide materials, we used a flexible synthetic route to prepare three series of calcium birnessites, where we varied the calcium concentrations, the ripening times of the original precipitates and the temperature of the heat treatment following the initial synthetic steps (tempering) during the preparation process. The products were carefully analysed by a number of analytical techniques and then probed for WOC activity using the Ce(4+)-system. We find that our set of twenty closely related manganese oxides shows large, but somewhat systematic alterations in catalytic rates, indicating the importance of synthesis parameters for maximum catalytic performance. The catalyst of the series for which the highest water-oxidation rate was found is a birnessite of medium calcium content (Ca : Mn ratio 0.2 : 1) that had been subjected to a tempering temperature of 400 °C. On the basis of the detailed analysis of the results, a WOC reaction scheme for birnessites is proposed to explain the observed trends in reactivity.

  4. Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

    KAUST Repository

    Xia, Chuan

    2015-11-05

    Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

  5. Destruction of representative submarine food waste using supercritical water oxidation.

    Science.gov (United States)

    Chen, Shiying; Qu, Xuan; Zhang, Rong; Bi, Jicheng

    2015-03-01

    In this study, 13 types of organic materials were oxidized using H2O2 in a continuous flow reactor under the condition of supercritical water. The effect of the operational parameters on the conversion of total organic carbon (TOC) and total nitrogen (TN) was investigated, and the resulting quality of treated water was analyzed. It was found that these materials were easily oxidized with a TOC conversion achieving 99% at temperature of 460 °C and TN conversion reaching 94% at temperature of 500 °C. Rice decomposition was rapid, with TOC and TN decomposition rates of 99% obtained within residence of 100 s at temperature of 460 °C. At temperature of 460 °C, pressure of 24 MPa, residence time of 100 s, and excess oxygen of 100%, the quality of treated water attained levels commensurate with China's Standards for Drinking Water Quality. Reaction rate equation parameters were obtained by fitting the experimental data to the differential equation obtained using the Runge-Kutta algorithm. The decrease of the TOC in water samples exhibited reaction orders of 0.95 for the TOC concentration and 0.628 for the oxygen concentration. The activation energy was 83.018 kJ/mol.

  6. Nonstoichiometric Titanium Oxides via Pulsed Laser Ablation in Water

    Directory of Open Access Journals (Sweden)

    Chen Shuei-Yuan

    2010-01-01

    Full Text Available Abstract Titanium oxide compounds TiO,Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density of ca. 1 × 108W/cm2 and 1011W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects. The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential optoelectronic and catalytic applications in UV–visible range and shed light on the Ti charge and phase behavior of titania-water binary in natural shock occurrence.

  7. Nonstoichiometric Titanium Oxides via Pulsed Laser Ablation in Water.

    Science.gov (United States)

    Huang, Chang-Ning; Bow, Jong-Shing; Zheng, Yuyuan; Chen, Shuei-Yuan; Ho, Newjin; Shen, Pouyan

    2010-04-13

    Titanium oxide compounds TiO,Ti2O3, and TiO2 with a considerable extent of nonstoichiometry were fabricated by pulsed laser ablation in water and characterized by X-ray/electron diffraction, X-ray photoelectron spectroscopy and electron energy loss spectroscopy. The titanium oxides were found to occur as nanoparticle aggregates with a predominant 3+ charge and amorphous microtubes when fabricated under an average power density of ca. 1 × 108W/cm2 and 1011W/cm2, respectively followed by dwelling in water. The crystalline colloidal particles have a relatively high content of Ti2+ and hence a lower minimum band gap of 3.4 eV in comparison with 5.2 eV for the amorphous state. The protonation on both crystalline and amorphous phase caused defects, mainly titanium rather than oxygen vacancies and charge and/or volume-compensating defects. The hydrophilic nature and presumably varied extent of undercoordination at the free surface of the amorphous lamellae accounts for their rolling as tubes at water/air and water/glass interfaces. The nonstoichiometric titania thus fabricated have potential optoelectronic and catalytic applications in UV-visible range and shed light on the Ti charge and phase behavior of titania-water binary in natural shock occurrence.

  8. Algal control and enhanced removal in drinking waters in Cairo, Egypt.

    Science.gov (United States)

    El-Dars, Farida M S E; Abdel Rahman, M A M; Salem, Olfat M A; Abdel-Aal, El-Sayed A

    2015-12-01

    Algal blooms at the major water treatment plants in Egypt have been reported since 2006. While previous studies focused on algal types and their correlation with disinfection by-products, correlation between raw water quality and algal blooms were not explored. Therefore, a survey of Nile water quality parameters at a major water intake in the Greater Cairo Urban Region was conducted from December 2011 to November 2012. Bench-scale experiments were conducted to evaluate the effectiveness of the conventional chloride/alum treatment compared with combined Cl/permanganate pre-oxidation with Al and Fe coagulants during the outbreak period. Addition of permanganate (0.5 mg/L) significantly reduced the chlorine demand from 5.5 to 2.7 mg/L. The applied alum coagulant dose was slightly reduced while residual Al was reduced by 27% and the algal count by 50% in the final treated waters. Applying ferric chloride and ferric sulfate as coagulants to waters treated with the combined pre-oxidation procedure effectively reduced algal count by 60% and better the total organic carbon reduction and residual aluminum in the treated water. Multivariate statistical analysis was used to identify the relationship between water quality parameters and occurrence of algae and to explain the impact of coagulants on the final water quality.

  9. Photoanodic Hybrid Semiconductor–Molecular Heterojunction for Solar Water Oxidation

    KAUST Repository

    Joya, Khurram Saleem

    2015-06-29

    Inorganic photo-responsive semiconducting materials have been employed in photoelectrochemical(PEC) water oxidation devicesin pursuit of solar to fuel conversion.[1]The reaction kinetics in semiconductors is limited by poor contact at the interfaces, and charge transfer is impeded by surface defects and the grain boundaries.[2]It has shown that successful surface functionalization of the photo-responsive semiconducting materials with co-catalysts can maximize the charge separation, hole delivery and its effective consumption, and enhances the efficiency and performane of the PEC based water oxidation assembly.[3]We present here unique modification of photoanodic hematite (α-Fe2O3) and bismuth vanadate (BiVO4) with molecular co-catalysts for enhanced photoelectrochemical water oxidation (Figure 1). These hybrid inorganic–organometallic heterojunctions manifest impressive cathodic shifts in the onset potentials, and the photocurrent densities have been enhanced by > 90% at all potentials relative to uncatalyzed α-Fe2O3 or BiVO4, and other catalyst-semiconductor based heterojunctions.This is a novel development in the solar to fuel conversion field, and is crucially important for designing a tandem device where light interfere very little with the catalyst layer on top of semiconducting light absorber.

  10. Transformation of a Cp*-iridium(III) precatalyst for water oxidation when exposed to oxidative stress.

    Science.gov (United States)

    Zuccaccia, Cristiano; Bellachioma, Gianfranco; Bortolini, Olga; Bucci, Alberto; Savini, Arianna; Macchioni, Alceo

    2014-03-17

    The reaction of [Cp*Ir(bzpy)NO3 ] (1; bzpy=2-benzoylpyridine, Cp*=pentamethylcyclopentadienyl anion), a competent water-oxidation catalyst, with several oxidants (H2 O2 , NaIO4 , cerium ammonium nitrate (CAN)) was studied to intercept and characterize possible intermediates of the oxidative transformation. NMR spectroscopy and ESI-MS techniques provided evidence for the formation of many species that all had the intact Ir-bzpy moiety and a gradually more oxidized Cp* ligand. Initially, an oxygen atom is trapped in between two carbon atoms of Cp* and iridium, which gives an oxygen-Ir coordinated epoxide, whereas the remaining three carbon atoms of Cp* are involved in a η(3) interaction with iridium (2 a). Formal addition of H2 O to 2 a or H2 O2 to 1 leads to 2 b, in which a double MeCOH functionalization of Cp* is present with one MeCOH engaged in an interaction with iridium. The structure of 2 b was unambiguously determined in the solid state and in solution by X-ray single-crystal diffractometry and advanced NMR spectroscopic techniques, respectively. Further oxidation led to the opening of Cp* and transformation of the diol into a diketone with one carbonyl coordinated at the metal (2 c). A η(3) interaction between the three non-oxygenated carbons of "ex-Cp*" and iridium is also present in both 2 b and 2 c. Isolated 2 b and mixtures of 2 a-c species were tested in water-oxidation catalysis by using CAN as sacrificial oxidant. They showed substantially the same activity than 1 (turnover frequency values ranged from 9 to 14 min(-1) ). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Use of Copper Oxide Nanoparticles for the Oxidative Degradation of Persistent Organic Water Pollutants

    Science.gov (United States)

    Dror, I.; Ben Moshe, T.; Berkowitz, B.

    2008-12-01

    The continuous release of persistent organic chemicals such as pesticides, halogenated organic solvents, PAHs, and PCBs to the subsurface environment is an unfortunate reality. These compounds are recognized as toxic, and often carcinogenic and/or mutagenic, and they thus require highly efficient treatment procedures in aqueous systems. The current study presents an oxidation process, to decontaminate polluted water, using nanosized copper oxide particles as the catalyst and hydrogen peroxide as the oxidation agent. The process shows complete and rapid degradation of a wide range of organic contaminants under ambient pressure and temperature. In contrast, control runs that measured the degradation through exposure to hydrogen peroxide only or copper oxide nanoparticles only showed less than 10% reduction in contaminant concentration, as compared to the complete degradation achieved when particles and oxidation agent were used. Lack of exposure to light and the method of mixing seem to have no influence on the reaction rate or products. The reaction was found to proceed effectively in the range pH 3-8.5, and much slower at pH 10. Testing various concentrations of oxidation agent, an optimum point was found, with an increase above this concentration resulting in a reduced reaction rate. Moreover, measurements of reaction kinetics demonstrated a conversion from exponential decay of a contaminant, typical of a first-order reaction, to a linear decrease in contaminant concentration which is typical of a pseudo-zero-order reaction. This behavior indicates that upon increase in oxidation agent concentration, a different reaction pathway which is independent of the contaminant concentration becomes the prevailing process. The copper oxide nanoparticles were characterized before and after the reaction, and also shown to retain reactivity for several cycles after refreshing the contaminant solution and adding more hydrogen peroxide.

  12. Chemical oxidation of unsymmetrical dimethylhydrazine transformation products in water

    Directory of Open Access Journals (Sweden)

    Madi Abilev

    2015-03-01

    Full Text Available Oxidation of unsymmetrical dimethylhydrazine (UDMH during a water treatment has several disadvantages including formation of stable toxic byproducts. Effectiveness of treatment methods in relation to UDMH transformation products is currently poorly studied. This work considers the effectiveness of chemical oxidants in respect to main metabolites of UDMH – 1-formyl-2,2-dimethylhydrazine, dimethylaminoacetontrile, N-nitrosodimethylamine and 1-methyl-1H-1,2,4-triazole. Experiments on chemical oxidation by Fenton's reagent, potassium permanganate and sodium nitrite were conducted. Quantitative determination was performed by HPLC. Oxidation products were identified by gas chromatography-mass spectrometry in combination with solid-phase microextraction. 1-Formyl-2,2-dimethylhydrazine was completely oxidized by Fenton's reagent with formation of formaldehyde N-formyl-N-methyl-hydrazone, 1,4-dihydro-1,4-dimethyl-5H-tetrazol-5-one by the action of potassium permanganate and N-methyl-N-nitro-methanamine in the presence of sodium nitrite. Oxidation of 1-formyl-2,2-dimethylhydrazine also resulted in formation of N-nitrosodimethylamine. Oxidation of dimethylaminoacetontrile proceeded with formation of hydroxyacetonitrile, dimethylformamide and 1,2,5-trimethylpyrrole. After 30 days, dimethylaminoacetontrile was not detected in the presence of Fenton’s reagent and potassium permanganate, but it’s concentration in samples with sodium nitrite was 77.3 mg/L. In the presence of Fenton’s reagent, potassium permanganate and sodium nitrite after 30 days, N-nitrosodimethylamine concentration decreased by 85, 80 and 50%, respectively. In control sample, N-nitrosodimethylamine concentration decreased by 50%, indicating that sodium nitrite has no effect of on N-nitrosodimethylamine concentration. Only Fenton's reagent allowed to reduce the concentration of 1-methyl-1H-1,2,4-triazole to 50% in 30 days. In the presence of other oxidants, 1-methyl-1H-1,2,4-triazole

  13. Water oxidation by manganese oxides formed from tetranuclear precursor complexes: the influence of phosphate on structure and activity.

    Science.gov (United States)

    Shevchenko, Denys; Anderlund, Magnus F; Styring, Stenbjörn; Dau, Holger; Zaharieva, Ivelina; Thapper, Anders

    2014-06-28

    Two types of manganese oxides have been prepared by hydrolysis of tetranuclear Mn(iii) complexes in the presence or absence of phosphate ions. The oxides have been characterized structurally using X-ray absorption spectroscopy and functionally by O2 evolution measurements. The structures of the oxides prepared in the absence of phosphate are dominated by di-μ-oxo bridged manganese ions that form layers with limited long-range order, consisting of edge-sharing MnO6 octahedra. The average manganese oxidation state is +3.5. The structure of these oxides is closely related to other manganese oxides reported as water oxidation catalysts. They show high oxygen evolution activity in a light-driven system containing [Ru(bpy)3](2+) and S2O8(2-) at pH 7. In contrast, the oxides formed by hydrolysis in the presence of phosphate ions contain almost no di-μ-oxo bridged manganese ions. Instead the phosphate groups are acting as bridges between the manganese ions. The average oxidation state of manganese ions is +3. This type of oxide has much lower water oxidation activity in the light-driven system. Correlations between different structural motifs and the function as a water oxidation catalyst are discussed and the lower activity in the phosphate containing oxide is linked to the absence of protonable di-μ-oxo bridges.

  14. Separation of tritiated water using graphene oxide membrane

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Motkuri, Radha K. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Gotthold, David W. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Fifield, Leonard S. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Frost, Anthony P. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Bratton, Wesley [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2015-06-28

    In future nuclear fuel reprocessing plants and possibly for nuclear power plants, the cleanup of tritiated water will be needed for hundreds of thousands of gallons of water with low activities of tritium. This cleanup concept utilizes graphene oxide laminar membranes (GOx) for the separation of low-concentration (10-3-10 µCi/g) tritiated water to create water that can be released to the environment and a much smaller waste stream with higher tritium concentrations. Graphene oxide membranes consist of hierarchically stacked, overlapping molecular layers and represent a new class of materials. A permeation rate test was performed with a 2-µm-thick cast Asbury membrane using mixed gas permeability testing with zero air (highly purified atmosphere) and with air humidified with either H2O or D2O to a nominal 50% relative humidity. The membrane permeability for both H2O and D2O was high with N2 and O2 at the system measurement limit. The membrane water permeation rate was compared to a Nafion® membrane and the GOx permeation was approximately twice as high at room temperature. The H2O vapor permeation rate was 5.9 × 102 cc/m2/min (1.2 × 10-6 g/min-cm2), which is typical for graphene oxide membranes. To demonstrate the feasibility of such isotopic water separation through GOX laminar membranes, an experimental setup was constructed to use pressure-driven separation by heating the isotopic water mixture at one side of the membrane to create steam while cooling the other side. Several membranes were tested and were prepared using different starting materials and by different pretreatment methods. The average separation result was 0.8 for deuterium and 0.6 for tritium. Higher or lower temperatures may also improve separation efficiency but neither has been tested yet. A rough estimate of cost compared to current technology was also included as an indication of potential viability of the process. The relative process costs were based on the rough size of facility to

  15. Concerted hydrogen-atom abstraction in photosynthetic water oxidation.

    Science.gov (United States)

    Westphal, K L; Tommos, C; Cukier, R I; Babcock, G T

    2000-06-01

    Photosystem II evolves oxygen by using water in the unlikely role of a reductant. The absorption of sunlight by chlorophyll produces highly oxidizing equivalents that are filled with electrons stripped from water. This proton-coupled redox chemistry occurs at the oxygen-evolving complex, which contains a tetramanganese cluster, a redox-active tyrosine amino acid hydrogen-bonded to a histidine amino acid, a calcium ion and chloride. Hydrogen-atom abstraction by the tyrosyl radical from water bound to the manganese cluster is now widely held to occur in this process, at least for some of the steps in the catalytic cycle. We discuss kinetic and energetic constraints on the hydrogen-atom abstraction process.

  16. TWR Bench-Scale Steam Reforming Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    D. W. Marshall; N. R. Soelberg

    2003-05-01

    The Idaho Nuclear Technology and Engineering Center (INTEC) was home to nuclear fuel reprocessing activities for decades at the Idaho National Engineering and Environmental Laboratory. As a result of the reprocessing activities, INTEC has accumulated approximately one million gallons of acidic, radioactive, sodium-bearing waste (SBW). The purpose of this demonstration was to investigate a reforming technology, offered by ThermoChem Waste Remediation, LLC, (TWR) for treatment of SBW into a "road ready" waste form that would meet the waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP). TWR is the licensee of Manufacturing Technology Conservation International (MTCI) steam-reforming technology in the field of radioactive waste treatment. A non-radioactive simulated SBW was used based on the known composition of waste tank WM-180 at INTEC. Rhenium was included as a non-radioactive surrogate for technetium. Data was collected to determine the nature and characteristics of the product, the operability of the technology, the composition of the off-gases, and the fate of key radionuclides (cesium and technetium) and volatile mercury compounds. The product contained a low fraction of elemental carbon residues in the cyclone and filter vessel catches. Mercury was quantitatively stripped from the product but cesium, rhenium (Tc surrogate), and the heavy metals were retained. Nitrate residues were about 400 ppm in the product and NOx destruction exceeded 86%. The demonstration was successful.

  17. TWR Bench-Scale Steam Reforming Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, D.W.; Soelberg, N.R.

    2003-05-21

    The Idaho Nuclear Technology and Engineering Center (INTEC) was home to nuclear fuel reprocessing activities for decades at the Idaho National Engineering and Environmental Laboratory. As a result of the reprocessing activities, INTEC has accumulated approximately one million gallons of acidic, radioactive, sodium-bearing waste (SBW). The purpose of this demonstration was to investigate a reforming technology, offered by ThermoChem Waste Remediation, LLC, (TWR) for treatment of SBW into a ''road ready'' waste form that would meet the waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP). TWR is the licensee of Manufacturing Technology Conservation International (MTCI) steam-reforming technology in the field of radioactive waste treatment. A non-radioactive simulated SBW was used based on the known composition of waste tank WM-180 at INTEC. Rhenium was included as a non-radioactive surrogate for technetium. Data was collected to determine the nature and characteristics of the product, the operability of the technology, the composition of the off-gases, and the fate of key radionuclides (cesium and technetium) and volatile mercury compounds. The product contained a low fraction of elemental carbon residues in the cyclone and filter vessel catches. Mercury was quantitatively stripped from the product but cesium, rhenium (Tc surrogate), and the heavy metals were retained. Nitrate residues were about 400 ppm in the product and NOx destruction exceeded 86%. The demonstration was successful.

  18. THOR Bench-Scale Steam Reforming Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    D. W. Marshall; N. R. Soelberg; K. M. Shaber

    2003-05-01

    The Idaho Nuclear Technology and Engineering Center (INTEC) was home to nuclear fuel reprocessing activities for decades at the Idaho National Engineering and Environmental Laboratory. As a result of the reprocessing activities, INTEC has accumulated approximately one million gallons of acidic, radioactive, sodium-bearing waste (SBW). The purpose of this demonstration was to investigate a reforming technology, offered by THORsm Treatment Technologies, LLC, for treatment of SBW into a "road ready" waste form that would meet the waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP). A non-radioactive simulated SBW was used based on the known composition of waste tank WM-180 at INTEC. Rhenium was included as a non-radioactive surrogate for technetium. Data was collected to determine the nature and characteristics of the product, the operability of the technology, the composition of the off-gases, and the fate of key radionuclides (cesium and technetium) and volatile mercury compounds. The product contained a low fraction of elemental carbon residues in the cyclone and filter vessel catches. Mercury was quantitatively stripped from the product but cesium, rhenium (Tc surrogate), and the heavy metals were retained. Nitrates were not detected in the product and NOx destruction exceeded 98%. The demonstration was successful.

  19. THOR Bench-Scale Steam Reforming Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, D.W.; Soelberg, N.R.; Shaber, K.M.

    2003-05-21

    The Idaho Nuclear Technology and Engineering Center (INTEC) was home to nuclear fuel reprocessing activities for decades at the Idaho National Engineering and Environmental Laboratory. As a result of the reprocessing activities, INTEC has accumulated approximately one million gallons of acidic, radioactive, sodium-bearing waste (SBW). The purpose of this demonstration was to investigate a reforming technology, offered by THORsm Treatment Technologies, LLC, for treatment of SBW into a ''road ready'' waste form that would meet the waste acceptance criteria for the Waste Isolation Pilot Plant (WIPP). A non-radioactive simulated SBW was used based on the known composition of waste tank WM-180 at INTEC. Rhenium was included as a non-radioactive surrogate for technetium. Data was collected to determine the nature and characteristics of the product, the operability of the technology, the composition of the off-gases, and the fate of key radionuclides (cesium and technetium) and volatile mercury compounds. The product contained a low fraction of elemental carbon residues in the cyclone and filter vessel catches. Mercury was quantitatively stripped from the product but cesium, rhenium (Tc surrogate), and the heavy metals were retained. Nitrates were not detected in the product and NOx destruction exceeded 98%. The demonstration was successful.

  20. Electrosynthesis of Biomimetic Manganese-Calcium Oxides for Water Oxidation Catalysis--Atomic Structure and Functionality.

    Science.gov (United States)

    González-Flores, Diego; Zaharieva, Ivelina; Heidkamp, Jonathan; Chernev, Petko; Martínez-Moreno, Elías; Pasquini, Chiara; Mohammadi, Mohammad Reza; Klingan, Katharina; Gernet, Ulrich; Fischer, Anna; Dau, Holger

    2016-02-19

    Water-oxidizing calcium-manganese oxides, which mimic the inorganic core of the biological catalyst, were synthesized and structurally characterized by X-ray absorption spectroscopy at the manganese and calcium K edges. The amorphous, birnesite-type oxides are obtained through a simple protocol that involves electrodeposition followed by active-site creation through annealing at moderate temperatures. Calcium ions are inessential, but tune the electrocatalytic properties. For increasing calcium/manganese molar ratios, both Tafel slopes and exchange current densities decrease gradually, resulting in optimal catalytic performance at calcium/manganese molar ratios of close to 10 %. Tracking UV/Vis absorption changes during electrochemical operation suggests that inactive oxides reach their highest, all-Mn(IV) oxidation state at comparably low electrode potentials. The ability to undergo redox transitions and the presence of a minor fraction of Mn(III) ions at catalytic potentials is identified as a prerequisite for catalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Photocatalytic polyoxometalate compositions of tungstovanadates and uses as water oxidation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Craig L.; Gueletii, Iourii V.; Song, Jie; Lv, Hongjin; Musaev, Djamaladdin; Luo, Zhen

    2017-08-22

    This disclosure relates to photocatalytic polyoxometalate compositions of tungstovanadates and uses as water oxidation catalysts. In certain embodiments, the disclosure relates to compositions comprising water, a complex of a tetra-metal oxide cluster and VW.sub.9O.sub.34 ligands, and a photosensitizer. Typically, the metal oxide cluster is Co. In certain embodiments, the disclosure relates to electrodes and other devices comprising water oxidation catalysts disclosed herein and uses in generating fuels and electrical power from solar energy.

  2. Application of UV/H2O2 system to treatment of wastewater arising from thermal treatment of oil-water emulsions

    Directory of Open Access Journals (Sweden)

    Ivanildo Hespanhol

    2009-12-01

    Full Text Available In this work it is presented the results of bench scale tests using Advanced Oxidation Process (AOP in a UV/H2O2 system, for the treatment of an industrial effluent with a high concentration of dissolved organic matter, resulted from thermal treatment of oil-water emulsions. Treatability tests were carried out in a batch photochemical system with recycle, and the raw effluent was characterized by the analysis of pH, turbidity, color, COD and TOC. Results from these assays shown that UV/H2O2 process is technically feasible resulting in TOC removal above 90%. However, for one log TOC removal from this effluent the energy required was about 455.5 kw.h.m-3, for an alpha relation of 10 mg H2O2/mg COT, resulting in a higher operational cost, considering the evaluated conditions.

  3. Eficiencia del proceso de lavado en la obtención del citrato de calcio y magnesio a escala de banco Effectiveness of washout process to obtain calcium and magnesium citrate at bench scale

    Directory of Open Access Journals (Sweden)

    Jorge E Rodríguez Chanfrau

    2010-03-01

    Full Text Available Como parte de la optimización del proceso tecnológico para obtener citrato de calcio y magnesio a partir de dolomitas, se estudió a escala de banco la etapa de lavado para disminuir el contenido de ácido cítrico libre. Las variantes de lavado estudiadas permitieron disminuir el contenido de ácido cítrico libre por debajo del 3 %, mientras que los valores de calcio y magnesio son similares a los del lote antes de realizar el proceso de lavado. Por otro lado, el estudio toxicológico en ratas, comprobó que los lotes a los cuales se les aplicó las diferentes variantes de lavado no provocaron irritabilidad gástrica a las dosis de 2 000 mg/kg de peso corporal, por lo que se puede afirmar que el proceso de lavado establecido es adecuado para garantizar la calidad de la materia prima.As part of the technological process optomization to obtain calcium citrate and magnesium from dolomites, we studied at bench scale, the washout stage to decrease the free citric acid content. Washout variants allowed to decrease the free citric acid content under 3 %, whereas the calcium and magnesium values are similar to those of batch before to carry out the wahout process. On the other hand, toxicity study in rats, proved that the batches where different washout variables were applied not provoke gastric irritability at doses of 2 000 mg/kg of body weight confirming that above mentioned established process is approproate to guarantee the raw material quality.

  4. Fundamental kinetics and mechanistic pathways for oxidation reactions in supercritical water

    Science.gov (United States)

    Webley, Paul A.; Tester, Jefferson W.

    1988-01-01

    Oxidation of the products of human metabolism in supercritical water has been shown to be an efficient way to accomplish the on-board water/waste recycling in future long-term space flights. Studies of the oxidation kinetics of methane to carbon dioxide in supercritical water are presented in this paper in order to enhance the fundamental understanding of the oxidation of human waste compounds in supercritical water. It is concluded that, although the elementary reaction models remain the best hope for simulating oxidation in supercritical water, several modifications to existing mechanisms need to be made to account for the role of water in the reaction mechanism.

  5. Engineered graphite oxide materials for application in water purification.

    Science.gov (United States)

    Gao, Wei; Majumder, Mainak; Alemany, Lawrence B; Narayanan, Tharangattu N; Ibarra, Miguel A; Pradhan, Bhabendra K; Ajayan, Pulickel M

    2011-06-01

    Retaining the inherent hydrophilic character of GO (graphite-oxide) nanosheets, sp(2) domains on GO are covalently modified with thiol groups by diazonium chemistry. The surface modified GO adsorbs 6-fold higher concentration of aqueous mercuric ions than the unmodified GO. "Core-shell" adsorbent granules, readily useable in filtration columns, are synthesized by assembling aqueous GO over sand granules. The nanostructured GO-coated sand retains at least 5-fold higher concentration of heavy metal and organic dye than pure sand. The research results could open avenues for developing low-cost water purification materials for the developing economies. © 2011 American Chemical Society

  6. Electro-assembly of a chromophore-catalyst bilayer for water oxidation and photocatalytic water splitting.

    Science.gov (United States)

    Ashford, Dennis L; Sherman, Benjamin D; Binstead, Robert A; Templeton, Joseph L; Meyer, Thomas J

    2015-04-13

    The use of electropolymerization to prepare electrocatalytically and photocatalytically active electrodes for water oxidation is described. Electropolymerization of the catalyst Ru(II)(bda)(4-vinylpyridine)2 (bda=2,2'-bipyridine-6,6'-dicarboxylate) on planar electrodes results in films containing semirigid polymer networks. In these films there is a change in the water oxidation mechanism compared to the solution analogue from bimolecular to single-site. Electro-assembly construction of a chromophore-catalyst structure on mesoporous, nanoparticle TiO2 films provides the basis for a dye-sensitized photoelectrosynthesis cell (DSPEC) for sustained water splitting in a pH 7 phosphate buffer solution. Photogenerated oxygen was measured in real-time by use of a two-electrode cell design. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. The effect of lanthanum(III) and cerium(III) ions between layers of manganese oxide on water oxidation.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Isaloo, Mohsen Abbasi; Hołyńska, Małgorzata; Shen, Jian-Ren; Allakhverdiev, Suleyman I; Allakhverdiev, Suleyman

    2015-12-01

    Manganese oxide structure with lanthanum(III) or cerium(III) ions between the layers was synthesized by a simple method. The ratio of Mn to Ce or La in samples was 0.00, 0.04, 0.08, 0.16, 0.32, 0.5, 0.82, or 1.62. The compounds were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction studies, and atomic absorption spectroscopy. The compounds show efficient catalytic activity of water oxidation in the presence of cerium(IV) ammonium nitrate with a turnover frequency of 1.6 mmol O2/mol Mn.s. In contrast to the water-oxidizing complex in Photosystem II, calcium(II) has no specific role to enhance the water-oxidizing activity of the layered manganese oxides and other cations can be replaced without any significant decrease in water-oxidizing activities of these layered Mn oxides. Based on this and previously reported results from oxygen evolution in the presence of H 2 (18) O, we discuss the mechanism and the important factors influencing the water-oxidizing activities of the manganese oxides.

  8. Iron oxide hydroxide nanoflower assisted removal of arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Raul, Prasanta Kumar, E-mail: prasanta.drdo@gmail.com [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Devi, Rashmi Rekha; Umlong, Iohborlang M. [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Thakur, Ashim Jyoti [Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784028, Assam (India); Banerjee, Saumen; Veer, Vijay [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India)

    2014-01-01

    Graphical abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. TEM image clearly reveals that the nanoparticle looks flower like morphology with average particle size less than 20 nm. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature and the data fitted to different isotherm models indicate the heterogeneity of the adsorbent surface. The material can be regenerated up to 70% using dilute hydrochloric acid and it would be utilized for de-arsenification purposes. - Highlights: • The work includes synthesis of iron oxide hydroxide nanoflower and its applicability for the removal of arsenic from water. • The nanoparticle was characterized using modern instrumental methods like FESEM, TEM, BET, XRD, etc. • The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature. • The sorption is multilayered on the heterogeneous surface of the nano adsorbent. • The mechanism of arsenic removal of IOH nanoflower follows both adsorption and ion-exchange. - Abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. The nanoparticle was characterized by X-ray powder diffraction analysis (XRD), BET surface area, FTIR, FESEM and TEM images. TEM image clearly reveals flower like morphology with average particle size less than 20 nm. The nanoflower morphology is also supported by FESEM images. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic and the data fitted to different isotherm models indicate the

  9. Effects of Gravity on Supercritical Water Oxidation (SCWO) Processes

    Science.gov (United States)

    Hegde, Uday; Hicks, Michael

    2013-01-01

    The effects of gravity on the fluid mechanics of supercritical water jets are being studied at NASA to develop a better understanding of flow behaviors for purposes of advancing supercritical water oxidation (SCWO) technologies for applications in reduced gravity environments. These studies provide guidance for the development of future SCWO experiments in new experimental platforms that will extend the current operational range of the DECLIC (Device for the Study of Critical Liquids and Crystallization) Facility on board the International Space Station (ISS). The hydrodynamics of supercritical fluid jets is one of the basic unit processes of a SCWO reactor. These hydrodynamics are often complicated by significant changes in the thermo-physical properties that govern flow behavior (e.g., viscosity, thermal conductivity, specific heat, compressibility, etc), particularly when fluids transition from sub-critical to supercritical conditions. Experiments were conducted in a 150 ml reactor cell under constant pressure with water injections at various flow rates. Flow configurations included supercritical jets injected into either sub-critical or supercritical water. Profound gravitational influences were observed, particularly in the transition to turbulence, for the flow conditions under study. These results will be presented and the parameters of the flow that control jet behavior will be examined and discussed.

  10. Warm Water Oxidation Verification - Scoping and Stirred Reactor Tests

    Energy Technology Data Exchange (ETDEWEB)

    Braley, Jenifer C.; Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2011-06-15

    Scoping tests to evaluate the effects of agitation and pH adjustment on simulant sludge agglomeration and uranium metal oxidation at {approx}95 C were performed under Test Instructions(a,b) and as per sections 5.1 and 5.2 of this Test Plan prepared by AREVA. (c) The thermal testing occurred during the week of October 4-9, 2010. The results are reported here. For this testing, two uranium-containing simulant sludge types were evaluated: (1) a full uranium-containing K West (KW) container sludge simulant consisting of nine predominant sludge components; (2) a 50:50 uranium-mole basis mixture of uraninite [U(IV)] and metaschoepite [U(VI)]. This scoping study was conducted in support of the Sludge Treatment Project (STP) Phase 2 technology evaluation for the treatment and packaging of K-Basin sludge. The STP is managed by CH2M Hill Plateau Remediation Company (CHPRC) for the U.S. Department of Energy. Warm water ({approx}95 C) oxidation of sludge, followed by immobilization, has been proposed by AREVA and is one of the alternative flowsheets being considered to convert uranium metal to UO{sub 2} and eliminate H{sub 2} generation during final sludge disposition. Preliminary assessments of warm water oxidation have been conducted, and several issues have been identified that can best be evaluated through laboratory testing. The scoping evaluation documented here was specifically focused on the issue of the potential formation of high strength sludge agglomerates at the proposed 95 C process operating temperature. Prior hydrothermal tests conducted at 185 C produced significant physiochemical changes to genuine sludge, including the formation of monolithic concretions/agglomerates that exhibited shear strengths in excess of 100 kPa (Delegard et al. 2007).

  11. Ruthenium Water Oxidation Catalysts based on Pentapyridyl Ligands.

    Science.gov (United States)

    Gil-Sepulcre, Marcos; Böhler, Michael; Schilling, Mauro; Bozoglian, Fernando; Bachmann, Cyril; Scherrer, Dominik; Fox, Thomas; Spingler, Bernhard; Gimbert-Suriñach, Carolina; Alberto, Roger; Bofill, Roger; Sala, Xavier; Luber, Sandra; Richmond, Craig J; Llobet, Antoni

    2017-11-23

    Ruthenium complexes containing the pentapyridyl ligand 6,6''-(methoxy(pyridin-2-yl)methylene)di-2,2'-bipyridine (L-OMe) of general formula trans-[Ru II (X)(L-OMe-κ-N 5 )] n+ (X=Cl, n=1, trans-1 + ; X=H 2 O, n=2, trans-2 2+ ) have been isolated and characterized in solution (by NMR and UV/Vis spectroscopy) and in the solid state by XRD. Both complexes undergo a series of substitution reactions at oxidation state Ru II and Ru III when dissolved in aqueous triflic acid-trifluoroethanol solutions as monitored by UV/Vis spectroscopy, and the corresponding rate constants were determined. In particular, aqueous solutions of the Ru III -Cl complex trans-[Ru III (Cl)(L-OMe-κ-N 5 )] 2+ (trans-1 2+ ) generates a family of Ru aquo complexes, namely trans-[Ru III (H 2 O)(L-OMe-κ-N 5 )] 3+ (trans-2 3+ ), [Ru III (H 2 O) 2 (L-OMe-κ-N 4 )] 3+ (trans-3 3+ ), and [Ru III (Cl)(H 2 O)(L-OMe-κ-N 4 )] 2+ (trans-4 2+ ). Although complex trans-4 2+ is a powerful water oxidation catalyst, complex trans-2 3+ has only a moderate activity and trans-3 3+ shows no activity. A parallel study with related complexes containing the methyl-substituted ligand 6,6''-(1-pyridin-2-yl)ethane-1,1-diyl)di-2,2'-bipyridine (L-Me) was carried out. The behavior of all of these catalysts has been rationalized based on substitution kinetics, oxygen evolution kinetics, electrochemical properties, and density functional theory calculations. The best catalyst, trans-4 2+ , reaches turnover frequencies of 0.71 s -1 using Ce IV as a sacrificial oxidant, with oxidative efficiencies above 95 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Ultrasound-assisted advanced oxidation processes for water decontamination.

    Science.gov (United States)

    Ince, Nilsun H

    2017-04-09

    The study reflects a part of my experience in sonochemistry and ultrasound-assisted advanced oxidation processes (AOPs) acquired during the last fifteen years with my research team. The data discussed were selected from studies with azo dyes, endocrine disrupting compounds and analgesic/anti-inflammatory pharmaceuticals, which are all classified as "hazardous" or "emerging" contaminants. The research focused on their treatability by ultrasound (US) and AOPs with emphasis on the mineralization of organic carbon. Some of the highlights as pointed out in the manuscript are: i) ultrasound is capable of partially or completely oxidizing the above contaminant groups if the operating conditions are properly selected and optimized, but incapable of mineralizing them; ii) the mechanism of degradation in homogeneous solutions is OH-mediated oxidation in the bulk solution or at the bubble-liquid interface, depending on the molecular properties of the contaminant, the applied frequency and pH; iii) US-assisted AOPs such as ozonation, UV/peroxide, Fenton and UV/Fenton are substantially more effective than ultrasound alone, particularly for the mineralization process; iv) catalytic processes involving TiO2, alumina and zero-valent iron and assisted by ultrasound are promising options not only for the destruction of the parent compounds, but also for the mineralization of their oxidation byproducts. The degradation reactions in heterogeneous solutions take place mostly at the catalyst surface despite the high-water solubility of the compounds; v) sonolytic modification of the above catalysts to reduce their particle size (to nano-levels) or to decorate the surface with metallic nanoparticles increases the catalytic activity under sonolysis, photolysis and both, and improves the stability of the catalyst. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Water as a Reagent for Soil Remediation

    Energy Technology Data Exchange (ETDEWEB)

    Jayaweera, Indira S.; Marti-Perez, Montserrat; Diaz-Ferrero, Jordi; Sanjurjo, Angel

    2003-03-06

    SRI International conducted experiments in a two-year, two-phase process to develop and evaluate hydrothermal extraction technology, also known as hot water extraction (HWE) technology, for remediating petroleum-contaminated soils. The bench-scale demonstration of the process has shown great promise, and the implementation of this technology will revolutionize the conventional use of water in soil remediation technologies and provide a standalone technology for removal of both volatile and heavy components from contaminated soil.

  14. Nanostructured Titanium Oxide Film- And Membrane-Based Photocatalysis For Water Treatment

    Science.gov (United States)

    Titanium Oxide (TiO2) photocatalysis, one of the ultraviolet (UV)-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness ...

  15. Bacterial Mercury Methylation At The Sediment-Water Interface Of Mercury Contaminated Sediments

    Science.gov (United States)

    Bench scale experiments were conducted to improve our understanding of bacterial mediation of mercury transformation (methylation), specifically those factors which govern the production of methyl mercury (MeHg) at the sediment-water interface. The greatest cause for concern re...

  16. Benefits of neutral electrolyzed oxidizing water as a drinking water additive for broiler chickens.

    Science.gov (United States)

    Bügener, E; Kump, A Wilms-Schulze; Casteel, M; Klein, G

    2014-09-01

    In the wake of discussion about the use of drugs in food-producing farms, it seems to be more and more important to search for alternatives and supportive measures to improve health. In this field trial, the influence of electrolyzed oxidizing (EO) water on water quality, drug consumption, mortality, and performance parameters such as BW and feed conversion rate was investigated on 2 broiler farms. At each farm, 3 rearing periods were included in the study. With EO water as the water additive, the total viable cell count and the number of Escherichia coli in drinking water samples were reduced compared with the respective control group. The frequency of treatment days was represented by the number of used daily doses per population and showed lower values in EO-water-treated groups at both farms. Furthermore, the addition of EO water resulted in a lower mortality rate. In terms of analyzed performance parameters, no significant differences were determined. In this study, the use of EO water improved drinking water quality and seemed to reduce the drug use without showing negative effects on performance parameters and mortality rates. © 2014 Poultry Science Association Inc.

  17. The Effect of Oxidant and Redox Potential on Metal Corrosion in Drinking Water

    Science.gov (United States)

    Future drinking water regulatory action may require some water utilities to consider additional and/or alternative oxidation and disinfection practices. There is little known about the effect of oxidant changes on the corrosion of drinking water distribution system materials and ...

  18. Diverse manganese(II)-oxidizing bacteria are prevalent in drinking water systems.

    Science.gov (United States)

    Marcus, Daniel N; Pinto, Ameet; Anantharaman, Karthik; Ruberg, Steven A; Kramer, Eva L; Raskin, Lutgarde; Dick, Gregory J

    2017-04-01

    Manganese (Mn) oxides are highly reactive minerals that influence the speciation, mobility, bioavailability and toxicity of a wide variety of organic and inorganic compounds. Although Mn(II)-oxidizing bacteria are known to catalyze the formation of Mn oxides, little is known about the organisms responsible for Mn oxidation in situ, especially in engineered environments. Mn(II)-oxidizing bacteria are important in drinking water systems, including in biofiltration and water distribution systems. Here, we used cultivation dependent and independent approaches to investigate Mn(II)-oxidizing bacteria in drinking water sources, a treatment plant and associated distribution system. We isolated 29 strains of Mn(II)-oxidizing bacteria and found that highly similar 16S rRNA gene sequences were present in all culture-independent datasets and dominant in the studied drinking water treatment plant. These results highlight a potentially important role for Mn(II)-oxidizing bacteria in drinking water systems, where biogenic Mn oxides may affect water quality in terms of aesthetic appearance, speciation of metals and oxidation of organic and inorganic compounds. Deciphering the ecology of these organisms and the factors that regulate their Mn(II)-oxidizing activity could yield important insights into how microbial communities influence the quality of drinking water. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Pilot-scale UV/H2O2 advanced oxidation process for municipal reuse water: Assessing micropollutant degradation and estrogenic impacts on goldfish (Carassius auratus L.).

    Science.gov (United States)

    Shu, Zengquan; Singh, Arvinder; Klamerth, Nikolaus; McPhedran, Kerry; Bolton, James R; Belosevic, Miodrag; Gamal El-Din, Mohamed

    2016-09-15

    Low concentrations (ng/L-μg/L) of emerging micropollutant contaminants in municipal wastewater treatment plant effluents affect the possibility to reuse these waters. Many of those micropollutants elicit endocrine disrupting effects in aquatic organisms resulting in an alteration of the endocrine system. A potential candidate for tertiary municipal wastewater treatment of these micropollutants is ultraviolet (UV)/hydrogen peroxide (H2O2) as an advanced oxidation process (AOP) which was currently applied to treat the secondary effluent of the Gold Bar Wastewater Treatment Plant (GBWWTP) in Edmonton, AB, Canada. A new approach is presented to predict the fluence-based degradation rate constants (kf') of environmentally occurring micropollutants including carbamazepine [(0.87-1.39) × 10(-3) cm(2)/mJ] and 2,4-Dichlorophenoxyacetic acid (2,4-D) [(0.60-0.91) × 10(-3) cm(2)/mJ for 2,4-D] in a medium pressure (MP) UV/H2O2 system based on a previous bench-scale investigation. Rather than using removal rates, this approach can be used to estimate the performance of the MP UV/H2O2 process for degrading trace contaminants of concern found in municipal wastewater. In addition to the ability to track contaminant removal/degradation, evaluation of the MP UV/H2O2 process was also accomplished by identifying critical ecotoxicological endpoints (i.e., estrogenicity) of the treated wastewater. Using quantitative PCR, mRNA levels of estrogen-responsive (ER) genes ERα1, ERα2, ERβ1, ERβ2 and NPR as well as two aromatase encoding genes (CYP19a and CYP19b) in goldfish (Carassius auratus L.) were measured during exposure to the GBWWTP effluent before and after MP UV/H2O2 treatment (a fluence of 1000 mJ/cm(2) and 20 mg/L of H2O2) in spring, summer and fall. Elevated expression of estrogen-responsive genes in goldfish exposed to UV/H2O2 treated effluent (a 7-day exposure) suggested that the UV/H2O2 process may induce acute estrogenic disruption to goldfish principally because

  20. Study of water vapour adsorption kinetics on aluminium oxide materials

    Science.gov (United States)

    Livanova, Alesya; Meshcheryakov, Evgeniy; Reshetnikov, Sergey; Kurzina, Irina

    2017-11-01

    Adsorbents on the basis of active aluminum oxide are still of demand on the adsorbent-driers market. Despite comprehensive research of alumina adsorbents, and currently is an urgent task to improve their various characteristics, and especially the task of increasing the sorption capacity. In the present work kinetics of the processes of water vapours' adsorption at room temperature on the surface of desiccant samples has been studied. It was obtained on the basis of bayerite and pseudoboehmite experimentally. The samples of pseudoboehmite modified with sodium and potassium ions were taken as study objects. The influence of an adsorbent's grain size on the kinetics of water vapours' adsorption was studied. The 0.125-0.25 mm and 0.5-1.0 mm fractions of this sample were used. It has been revealed that the saturation water vapor fine powder (0.125-0.25 mm) is almost twofold faster in comparison with the sample of fraction 0.5-1.0 mm due to the decrease in diffusion resistance in the pores of the samples when moving from the sample of larger fraction to the fine-dispersed sample. It has been established that the adsorption capacity of the pseudoboehmite samples, modified by alkaline ions, is higher by ˜40 %, than for the original samples on the basis of bayerite and pseudoboehmite.

  1. Supercritical water oxidation for wastewater treatment Preliminary study of urea destruction

    Science.gov (United States)

    Timberlake, S. H.; Hong, G. T.; Simson, M.; Modell, M.

    1982-01-01

    Supercritical water oxidation is being investigated as a method of treating spacecraft wastewater for recycle. In this process, oxidation is conducted in an aqueous phase maintained above the critical temperature (374 C) and pressure (215 bar) of water. Organic materials are oxidized with efficiencies greater than 99.99 percent in residence times of less than 1 minute. This paper presents preliminary results for urea destruction. Above 650 C, urea can be completely broken down to nitrogen gas, carbon dioxide and water by supercritical water oxidation, without the use of a specific catalyst.

  2. Archaea dominate ammonia oxidizers in the permian water ecosystem of midland basin.

    Science.gov (United States)

    Hong, Yiguo; Youshao, Wang; Chen, Feng

    2013-01-01

    We investigated the existence and characteristics of ammonia oxidizers in Permian water from Midland Basin. Molecular surveys targeting the amoA gene showed that only ammonia-oxidizing archaea (AOA) exist and have potential activity in this special environment. In contrast, no ammonia-oxidizing bacteria (AOB) were detected in the water. Phylogenetic analysis indicated that 72-89% of the total screened AOA clones were affiliated with those found in underground water, and 10-24% of the AOA clones were related to those found in marine water or sediments. Our results indicate AOA might be the most abundant ammonia-oxidizing microbes in this ecological niche.

  3. Supercritical water oxidation of acrylic acid production wastewater.

    Science.gov (United States)

    Gong, Y M; Wang, S Z; Tang, X Y; Xu, D H; Ma, H H

    2014-01-01

    Supercritical water oxidation (SCWO) of wastewater from an acrylic acid manufacturing plant has been studied on a continuous flow experimental system, whose reactor was made of Hastelloy C-276. Experimental conditions included a reaction temperature (T) ranging from 673 to 773K, a residence time (t) ranging from 72.7 to 339s, a constant pressure (P) of 25 MPa and a fixed oxidation coefficient (alpha) of 2.0. Experimental results indicated that reaction temperature and residence time had significant influences on the oxidation reaction, and increasing the two operation parameters could improve both degradation of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N). The COD removal efficiency could reach up to 98.73% at 25 MPa, 773 K and 180.1 s, whereas the destruction efficiency of NH3-N was only 43.71%. We further carried out a kinetic analysis considering the induction period through free radical chain mechanism. It confirms that the power-law rate equation for COD removal was 345 exp(-52200/RT)[COD]1.98[O2]0.17 and for NH3-N removal was 500 exp(-64492.19/RT)[NH3-N]1.87 [O2]0.03. Moreover, the induction time formulations for COD and NH3-N were suspected to be exp(38250/RT)/173 and exp(55690/RT)/15231, respectively. Correspondingly, induction time changed from 2.22 to 5.38 s for COD and 0.38 to 1.38 s for NH3-N. Owing to the catalysis of reactor inner wall surface, more than 97% COD removal was achieved in all samples.

  4. Diffusion Limited Supercritical Water Oxidation (SCWO) in Microgravity Environments

    Science.gov (United States)

    Hicks, M. C.; Lauver, R. W.; Hegde, U. G.; Sikora, T. J.

    2006-01-01

    Tests designed to quantify the gravitational effects on thermal mixing and reactant injection in a Supercritical Water Oxidation (SCWO) reactor have recently been performed in the Zero Gravity Facility (ZGF) at NASA s Glenn Research Center. An artificial waste stream, comprising aqueous mixtures of methanol, was pressurized to approximately 250 atm and then heated to 450 C. After uniform temperatures in the reactor were verified, a controlled injection of air was initiated through a specially designed injector to simulate diffusion limited reactions typical in most continuous flow reactors. Results from a thermal mapping of the reaction zone in both 1-g and 0-g environments are compared. Additionally, results of a numerical model of the test configuration are presented to illustrate first order effects on reactant mixing and thermal transport in the absence of gravity.

  5. Environmental assessment of supercritical water oxidation of sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Svanstrom, Magdalena; Froling, Morgan [Department of Chemical Engineering and Environmental Science, Chalmers University of Technology, SE-412 96 Goteborg (Sweden); Modell, Michael; Peters, William A.; Tester, Jefferson [Laboratory For Energy and the Environment (LFEE), Massachusetts Institute of Technology (MIT), Building E40, 1 Amherst Street, Cambridge, MA 02139 (United States)

    2004-07-01

    Environmental aspects of using supercritical water oxidation (SCWO) to treat sewage sludge were studied using a life cycle assessment (LCA) methodology. The system studied is the first commercial scale SCWO plant for sewage sludge in the world, treating sludge from the municipal wastewater treatment facility in Harlingen, TX, USA. The environmental impacts were evaluated using three specific environmental attributes: global warming potential (GWP), photo-oxidant creation potential (POCP) and resource depletion; as well as two single point indicators: EPS2000 and EcoIndicator99. The LCA results show that for the described process, gas-fired preheating of the sludge is the major contributor to environmental impacts, and emissions from generating electricity for pumping and for oxygen production are also important. Overall, SCWO processing of undigested sewage sludge is an environmentally attractive technology, particularly when heat is recovered from the process. Energy-conserving measures and recovery of excess oxygen from the SCWO process should be considered for improving the sustainability potential.

  6. Electrochemically Reduced Water Protects Neural Cells from Oxidative Damage

    Directory of Open Access Journals (Sweden)

    Taichi Kashiwagi

    2014-01-01

    Full Text Available Aging-related neurodegenerative disorders are closely associated with mitochondrial dysfunction and oxidative stresses and their incidence tends to increase with aging. Brain is the most vulnerable to reactive species generated by a higher rate of oxygen consumption and glucose utilization compared to other organs. Electrochemically reduced water (ERW was demonstrated to scavenge reactive oxygen species (ROS in several cell types. In the present study, the protective effect of ERW against hydrogen peroxide (H2O2 and nitric oxide (NO was investigated in several rodent neuronal cell lines and primary cells. ERW was found to significantly suppress H2O2 (50–200 μM induced PC12 and SFME cell deaths. ERW scavenged intracellular ROS and exhibited a protective effect against neuronal network damage caused by 200 μM H2O2 in N1E-115 cells. ERW significantly suppressed NO-induced cytotoxicity in PC12 cells despite the fact that it did not have the ability to scavenge intracellular NO. ERW significantly suppressed both glutamate induced Ca2+ influx and the resulting cytotoxicity in primary cells. These results collectively demonstrated for the first time that ERW protects several types of neuronal cells by scavenging ROS because of the presence of hydrogen and platinum nanoparticles dissolved in ERW.

  7. Nitric oxide reduces oxidative damage induced by water stress in sunflower plants

    Directory of Open Access Journals (Sweden)

    Inês Cechin

    2015-06-01

    Full Text Available Drought is one of the main environmental constraints that can reduce plant yield. Nitric oxide (NO is a signal molecule involved in plant responses to several environmental stresses. The objective of this study was to investigate the cytoprotective effect of a single foliar application of 0, 1, 10 or 100 µM of the NO donor sodium nitroprusside (SNP in sunflower plants under water stress. Water stressed plants treated with 1μM SNP showed an increase in the relative water content compared with 0 μM SNP. Drought reduced the shoot dry weight but SNP applications did not result in alleviation of drought effects. Neither drought nor water stress plus SNP applications altered the content of photosynthetic pigments. Stomatal conductance was reduced by drought and this reduction was accompanied by a significant reduction in intercellular CO2 concentration and photosynthesis. Treatment with SNP did not reverse the effect of drought on the gas exchange characteristics. Drought increased the level of malondialdehyde (MDA and proline and reduced pirogalol peroxidase (PG-POD activity, but did not affect the activity of superoxide dismutase (SOD. When the water stressed plants were treated with 10 μM SNP, the activity of PG-POD and the content of proline were increased and the level of MDA was decreased. The results show that the adverse effects of water stress on sunflower plants are dependent on the external NO concentration. The action of NO may be explained by its ability to increase the levels of antioxidant compounds and the activity of ROS-scavenging enzymes.

  8. Oxidation of X20 in Water Vapour: The Effect of Temperature and Oxygen Partial Pressure

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Montgomery, Melanie; Somers, Marcel A. J.

    2009-01-01

    The oxidation behaviour of X20 in various mixtures of water, oxygen and hydrogen was investigated at temperatures between 500 C and 700 C (time: 336 h). The samples were characterised using reflected light microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy....... Double-layered oxides developed during oxidation under all conditions. The morphology of the oxide layers was strongly influenced by temperature, whereas the influence of the oxidising environment appeared to be less pronounced, as long as it contained water vapour. The inner layer consisted of converted...... M23C6 embedded in Fe–Cr spinel after oxidation at 500 and 600 C, while alternating layers of Cr-rich and Cr-poor oxide were observed after oxidation at 700 C. An internal oxidation zone developed during oxidation at 500 and 600 C, with its depth influenced by the oxidising environments. The results...

  9. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Concepcion Corbea, Javier Jesus; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L; Hoertz, Paul; Meyer, Thomas J

    2014-10-28

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  10. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Corbea, Javier Jesus Concepcion; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2013-09-03

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  11. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Corbea, Javier Jesus Concepcion; Chen, Zoufeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2016-06-07

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  12. High-Performance Supported Iridium Oxohydroxide Water Oxidation Electrocatalysts.

    Science.gov (United States)

    Massué, Cyriac; Pfeifer, Verena; Huang, Xing; Noack, Johannes; Tarasov, Andrey; Cap, Sébastien; Schlögl, Robert

    2017-05-09

    The synthesis of a highly active and yet stable electrocatalyst for the anodic oxygen evolution reaction (OER) remains a major challenge for acidic water splitting on an industrial scale. To address this challenge, we obtained an outstanding high-performance OER catalyst by loading Ir on conductive antimony-doped tin oxide (ATO)-nanoparticles by a microwave (MW)-assisted hydrothermal route. The obtained Ir phase was identified by using XRD as amorphous (XRD-amorphous), highly hydrated IrIII/IV oxohydroxide. To identify chemical and structural features responsible for the high activity and exceptional stability under acidic OER conditions with loadings as low as 20 μgIr  cm-2 , we used stepwise thermal treatment to gradually alter the XRD-amorphous Ir phase by dehydroxylation and crystallization of IrO2 . This resulted in dramatic depletion of OER performance, indicating that the outstanding electrocatalytic properties of the MW-produced IrIII/IV oxohydroxide are prominently linked to the nature of the produced Ir phase. This finding is in contrast with the often reported stable but poor OER performance of crystalline IrO2 -based compounds produced through more classical calcination routes. Our investigation demonstrates the immense potential of Ir oxohydroxide-based OER electrocatalysts for stable high-current water electrolysis under acidic conditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Water Injection on Commercial Aircraft to Reduce Airport Nitrogen Oxides

    Science.gov (United States)

    Daggett, David L.; Hendricks, Robert C.; Fucke, Lars; Eames, David J. H.

    2010-01-01

    The potential nitrogen oxide (NO(x) reductions, cost savings, and performance enhancements identified in these initial studies of waterinjection technology strongly suggest that it be further pursued. The potential for engine maintenance cost savings from this system should make it very attractive to airline operators and assure its implementation. Further system tradeoff studies and engine tests are needed to answer the optimal system design question. Namely, would a low-risk combustor injection system with 70- to 90-percent NO(x) reduction be preferable, or would a low-pressure compressor (LPC) misting system with only 50-percent NO(x) reduction but larger turbine inlet temperature reductions be preferable? The low-pressure compressor injection design and operability issues identified in the report need to be addressed because they might prevent implementation of the LPC type of water-misting system. If water-injection technology challenges are overcome, any of the systems studied would offer dramatic engine NO(x) reductions at the airport. Coupling this technology with future emissions-reduction technologies, such as fuel-cell auxiliary power units will allow the aviation sector to address the serious challenges of environmental stewardship, and NO(x) emissions will no longer be an issue at airports.

  14. Oxidation of manganese(II) with ferrate: Stoichiometry, kinetics, products and impact of organic carbon.

    Science.gov (United States)

    Goodwill, Joseph E; Mai, Xuyen; Jiang, Yanjun; Reckhow, David A; Tobiason, John E

    2016-09-01

    Manganese is a contaminant of concern for many drinking water utilities, and future regulation may be pending. An analysis of soluble manganese (Mn(II)) oxidation by ferrate (Fe(VI)) was executed at the bench-scale, in a laboratory matrix, both with and without the presence of natural organic matter (NOM) and at two different pH values, 6.2 and 7.5. In the matrix without NOM, the oxidation of Mn(II) by Fe(VI) followed a stoichiometry of 2 mol Fe(VI) to 3 mol Mn(II). The presence of NOM did not significantly affect the stoichiometry of the oxidation reaction, indicating relative selectivity of Fe(VI) for Mn(II). The size distribution of resulting particles included significant amounts of nanoparticles. Resulting manganese oxide particles were confirmed to be MnO2 via X-ray photoelectron spectroscopy. The rate of the Mn(II) oxidation reaction was fast relative to typical time scales in drinking water treatment, with an estimated second order rate constant of approximately 1 × 10(4) M(-1) s(-1) at pH 9.2 and > 9 × 10(4) M(-1) s(-1) at pH 6.2. In general, ferrate is a potential option for Mn(II) oxidation in water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Preparation and Characterization of Reduced Graphene Oxide Sheets via Water-Based Exfoliation and Reduction Methods

    Directory of Open Access Journals (Sweden)

    Vorrada Loryuenyong

    2013-01-01

    Full Text Available This research studied the synthesis of graphene oxide and graphene via a low-cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by modified Hummer’s method, followed by the exfoliation of graphite oxide in distilled water using the ultrasound frequency from a laboratory ultrasonic bath. Finally, the oxygen functional groups on exfoliated graphite oxide or graphene oxide were eliminated by stirring in hot distilled water at 95°C, as a replacement for highly toxic and dangerously unstable hydrazine. The results assured that stirring in hot distilled water could give the product of graphene or reduced graphene oxide. The samples were characterized by FTIR, XRD, TGA, Raman spectroscopy, SEM, and TEM methods.

  16. Enhancing Hematite Photoanode Activity for Water Oxidation by Incorporation of Reduced Graphene Oxide.

    Science.gov (United States)

    do Amaral Carminati, Saulo; Souza, Flavio L; Nogueira, Ana F

    2016-01-04

    Two effective methods to prepare reduced graphene oxide (rGO)/hematite nanostructured photoanodes and their photoelectrochemical characterization towards water splitting reactions are presented. First, graphene oxide (GO) is reduced to rGO using hydrazine in a basic solution containing tetrabutylammonium hydroxide (TBAOH), and then deposited over the nanostructured hematite photoanodes previously treated at 750 °C for 30 min. The second method follows the deposition of a paste containing a mixture of hematite nanoparticles and rGO sheets by the doctor-blade method, varying the rGO concentration. Since hematite suffers from low electron mobility, a low absorption coefficient, high recombination rates and slow reaction kinetics, the incorporation of rGO in the hematite can overcome such limitations due to graphene's exceptional properties. Using the first method, the rGO incorporation results in a photocurrent density increase from 0.56 to 0.82 mA cm(-2) at 1.23 VRHE. Our results indicate that the rGO incorporation in the hematite photoanodes shows a positive effect in the reduction of the electron-hole recombination rate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Water Sorption and Radiolysis Studies for Neptunium Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2004-02-03

    Plans are to convert the {sup 237}Np that is currently stored as a nitrate solution at the Savannah River Site to NpO{sub 2} and then ship it to the Y-12 National Security Complex in Oak Ridge for interim storage. This material will serve as feedstock for the {sup 238}Pu production program, and some will be periodically shipped to the Oak Ridge National Laboratory (ORNL) for fabrication into targets. The safe storage of this material requires an understanding of the radiolysis of moisture that is sorbed on the oxides, which, in turn, provides a basis for storage criteria (namely, moisture content). A two-component experimental program has been undertaken at ORNL to evaluate the radiolytic effects on NpO{sub 2}: (1) moisture uptake experiments and (2) radiolysis experiments using both gamma and alpha radiation. These experiments have produced two key results. First, the water uptake experiments demonstrated that the 0.5 wt % moisture limit that has been typically established for similar materials (e.g., uranium and plutonium oxides) cannot be obtained in a practical environment. In fact, the uptake in a typical environment can be expected to be at least an order of magnitude lower than the limit. The second key result is the establishment of steady-state pressure plateaus as a result of the radiolysis of sorbed moisture. These plateaus are the result of back reactions that limit the overall pressure increase and H{sub 2} production. These results clearly demonstrate that 0.5 wt % H{sub 2}O on NpO{sub 2} is safe for long-term storage--if such a moisture content could even be practically reached.

  18. Sea-urchin-like iron oxide nanostructures for water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Uk, E-mail: leeho@kbsi.re.kr [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Soon Chang [Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lee, Young-Chul [Department of Biological Engineering, College of Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Vrtnik, Stane; Kim, Changsoo; Lee, SangGap [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Young Boo; Nam, Bora [Jeonju Center, Korea Basic Science Institute, Jeonju 561-756 (Korea, Republic of); Lee, Jae Won [Department of Energy Engineering, Dankook University, Cheonan 330-714 (Korea, Republic of); Park, So Young; Lee, Sang Moon [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Jouhahn, E-mail: jouhahn@kbsi.re.kr [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of)

    2013-11-15

    Highlights: • The u-MFN were synthesized via a ultrasound irradiation and/or calcinations process. • The u-MFN exhibited excellent adsorption capacities. • The u-MFN also displayed excellent adsorption of organic polluent after recycling. • The u-MFN has the potential to be used as an efficient adsorbent material. -- Abstract: To obtain adsorbents with high capacities for removing heavy metals and organic pollutants capable of quick magnetic separation, we fabricated unique sea-urchin-like magnetic iron oxide (mixed γ-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} phase) nanostructures (called u-MFN) with large surface areas (94.1 m{sup 2} g{sup −1}) and strong magnetic properties (57.9 emu g{sup −1}) using a simple growth process and investigated their potential applications in water treatment. The u-MFN had excellent removal capabilities for the heavy metals As(V) (39.6 mg g{sup −1}) and Cr(VI) (35.0 mg g{sup −1}) and the organic pollutant Congo red (109.2 mg g{sup −1}). The u-MFN also displays excellent adsorption of Congo red after recycling. Because of its high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the u-MFN developed in the present study is expected to be an efficient magnetic adsorbent for heavy metals and organic pollutants in aqueous solutions.

  19. The mechanism change by switching the reactants from water to hydroxyl ions for electrocatalytic water oxidation: a case study of copper oxide microspheres.

    Science.gov (United States)

    Du, Xiaoqiang; Huang, Jingwei; Ding, Yong

    2017-06-06

    Developing noble metal-free water oxidation catalysts is essential for many energy conversion/storage processes (e.g., water splitting). Herein, we report a facile synthesis of CuO microspheres composed of ultrathin, single-crystal-like nanosheets via a simple solution method. The as-obtained CuO microspheres can serve as an active and stable water oxidation catalyst under electrochemical reaction conditions, owing to their unique structural features. In electrochemical water oxidation, this catalyst affords a current density of 10 mA cm-2 (a value related to practical relevance) at an overpotential of ∼0.48 V. Pure CuO was reported as a water oxidation catalyst (WOC) from near-neutral conditions to alkalescent conditions. Electrochemistry values agree with the Nernstian behavior, suggesting ne-/nH+ transfer prior to a chemical rate-determining step. Our results suggest that the delicate nanostructure can offer unique advantages for developing efficient water oxidation catalysts.

  20. Supercritical water oxidation of oil-based drill cuttings.

    Science.gov (United States)

    Chen, Zhong; Chen, Zeliang; Yin, Fengjun; Wang, Guangwei; Chen, Hongzhen; He, Chunlan; Xu, Yuanjian

    2017-06-15

    Oil-based drill cuttings (OBDC) are a typical hazardous solid waste that arises from drilling operations in oil and gas fields. The supercritical water oxidation (SCWO) of OBDC was comprehensively investigated in a batch reactor under the conditions of various oxygen coefficients (OC, 1.5-3.5), temperatures (T, 400-500°C) and reaction times (t, 0.5-10min). Preheating experiments indicated that most of the organic compounds in the initial OBDC sample were distributed within gaseous, oil, aqueous and solid phases, with no more than 9.8% of organic compounds converted into inorganic carbon. All tested variables, i.e., OC, T and t, positively affect the transformation of carbon compounds from the oil and solid phases to the aqueous phase and, ultimately, to CO 2 . Carbon monoxide is the primary stable intermediate. The total organic carbon (TOC) removal efficiency can reach up to 89.2% within 10min at 500°C. Analysis of the reaction pathways suggests both homogeneous and heterogeneous reactions exist in the reactor. The homogeneous reaction is a typical SCWO reaction that is governed by a free radical mechanism, and the heterogeneous reaction is dominated by mass transfer. The information obtained in this study is useful for further investigation and development of hydrothermal treatment procedures for OBDC. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Copper oxide--copper sulfate water-splitting cycle

    Energy Technology Data Exchange (ETDEWEB)

    Foh, S. E.; Schreiber, J. D.; Dafler, J. R.

    1978-08-01

    A hybrid copper oxide--copper sulfate thermochemical water-splitting cycle, IGT's H-5, has been demonstrated in the laboratory with recycled materials. The optimum configuration and operating conditions for the electrolytic hydrogen-producing step have not yet been defined. With cooperative funding (A.G.A./G.R.I./DOE) a conceptual flowsheet was developed for this cycle and a load-line efficiency of about 37% calculated. This figure is the result of a single iteration on the original base case flow sheet and compares well with the values calculated for other processes at this stage of development. An iterative optimization of process conditions would improve efficiency. The data required to perform an economic analysis are not yet available and the electrolysis step must be more fully defined. An attractive process efficiency, relatively few corrosive materials, and few gas-phase separations are attributes of Cycle H-5 that lead us to believe hydrogen costs (to be developed during future analyses) would be improved significantly over similar processes analyzed to date.

  2. Comparison of nano-sized Mn oxides with the Mn cluster of photosystem II as catalysts for water oxidation.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Ghobadi, Mohadeseh Zarei; Haghighi, Behzad; Tomo, Tatsuya; Shen, Jian-Ren; Allakhverdiev, Suleyman I

    2015-02-01

    "Back to Nature" is a promising way to solve the problems that we face today, such as air pollution and shortage of energy supply based on conventional fossil fuels. A Mn cluster inside photosystem II catalyzes light-induced water-splitting leading to the generation of protons, electrons and oxygen in photosynthetic organisms, and has been considered as a good model for the synthesis of new artificial water-oxidizing catalysts. Herein, we surveyed the structural and functional details of this cluster and its surrounding environment. Then, we review the mechanistic findings concerning the cluster and compare this biological catalyst with nano-sized Mn oxides, which are among the best artificial Mn-based water-oxidizing catalysts. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. The burnup dependence of light water reactor spent fuel oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, B.D.

    1998-07-01

    Over the temperature range of interest for dry storage or for placement of spent fuel in a permanent repository under the conditions now being considered, UO{sub 2} is thermodynamically unstable with respect to oxidation to higher oxides. The multiple valence states of uranium allow for the accommodation of interstitial oxygen atoms in the fuel matrix. A variety of stoichiometric and nonstoichiometric phases is therefore possible as the fuel oxidizers from UO{sub 2} to higher oxides. The oxidation of UO{sub 2} has been studied extensively for over 40 years. It has been shown that spent fuel and unirradiated UO{sub 2} oxidize via different mechanisms and at different rates. The oxidation of LWR spent fuel from UO{sub 2} to UO{sub 2.4} was studied previously and is reasonably well understood. The study presented here was initiated to determine the mechanism and rate of oxidation from UO{sub 2.4} to higher oxides. During the early stages of this work, a large variability in the oxidation behavior of samples oxidized under nearly identical conditions was found. Based on previous work on the effect of dopants on UO{sub 2} oxidation and this initial variability, it was hypothesized that the substitution of fission product and actinide impurities for uranium atoms in the spent fuel matrix was the cause of the variable oxidation behavior. Since the impurity concentration is roughly proportional to the burnup of a specimen, the oxidation behavior of spent fuel was expected to be a function of both temperature and burnup. This report (1) summarizes the previous oxidation work for both unirradiated UO{sub 2} and spent fuel (Section 2.2) and presents the theoretical basis for the burnup (i.e., impurity concentration) dependence of the rate of oxidation (Sections 2.3, 2.4, and 2.5), (2) describes the experimental approach (Section 3) and results (Section 4) for the current oxidation tests on spent fuel, and (3) establishes a simple model to determine the activation energies

  4. Disinfection of Pythium-infested recirculation water by UV-oxidation technology.

    Science.gov (United States)

    Runia, W T; Boonstra, S

    2001-01-01

    Selective disinfection against Pythium aphanidermatum in recirculation water was tested with UV-irradiation and with UV-oxidation technology with the objective to reduce the electrical energy consumption per cubic meter treated water. UV-oxidation technology is based on injection of hydrogen peroxide in recirculation water, just before passage along a UV-lamp, thus creating hydroxyl radicals. Pythium aphanidermatum was applied artificially to recirculation water from tomatoes, grown, in rockwool and coconut fibre. Other parameters in this study were pH and transmission value (T10) of the infested recirculation water. Results indicated that the recommended UV-C dose of 100 mJ/cm2 for elimination of fungal pathogens in general can be lowered in case recirculation water is infected with Pythium aphanidermatum only. When UV-oxidation technology was applied with 1 mmol hydrogen peroxide per litre recirculation water, the UV-C dose could be reduced even more in comparison with merely UV irradiation.

  5. Advanced Oxidation Technology for Potable Water Disinfection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The availability of high-quality potable water is essential in crewed space missions. Closed loop water recycling systems as well as potable water holding tanks and...

  6. Importance of trivalency and the eg1 configuration in the photocatalytic oxidation of water by Mn and Co oxides

    Science.gov (United States)

    Maitra, Urmimala; Naidu, B. S.; Govindaraj, A.; Rao, C. N. R.

    2013-01-01

    Prompted by the early results on the catalytic activity of LiMn2O4 and related oxides in the photochemical oxidation of water, our detailed study of several manganese oxides has shown that trivalency of Mn is an important factor in determining the catalytic activity. Thus, Mn2O3, LaMnO3, and MgMn2O4 are found to be very good catalysts with turnover frequencies of 5 × 10−4 s−1, 4.8 × 10−4 s−1, and 0.8 ×10−4 s−1, respectively. Among the cobalt oxides, Li2Co2O4 and LaCoO3—especially the latter—exhibit excellent catalytic activity, with the turnover frequencies being 9 × 10−4 s−1 and 1.4 × 10−3 s−1, respectively. The common feature among the catalytic Mn and Co oxides is not only that Mn and Co are in the trivalent state, but Co3+ in the Co oxides is in the intermediate t2g5eg1 state whereas Mn3+ is in the t2g3eg1 state. The presence of the eg1 electron in these Mn and Co oxides is considered to play a crucial role in the photocatalytic properties of the oxides. PMID:23818589

  7. Emulsification technique affects oxidative stability of fish oil-in-water emulsions

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jensen, Louise Helene Søgaard

    In oil-in-water emulsions, lipid oxidation is expected to be initiated at the oil-water interface. The properties of the emulsifier used, and the structure at the interface is therefore expected to be of great importance for lipid oxidation in emulsions. Previous studies have shown that e...... of this study was to compare lipid oxidation in 10% fish oil-in-water emulsions prepared by two different kinds of high pressure homogenizers i.e. a microfluidizer and a two valve high pressure homogenizer. Emulsions were made with equal droplet sizes, and with either 1% sodium caseinate or 1% whey protein...

  8. Emulsification technique affects oxidative stability of fish oil-in-water emulsion

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jensen, Louise Helene Søgaard

    In oil-in-water emulsions, lipid oxidation is expected to be initiated at the oil-water interface. The properties of the emulsifier used, and the structure at the interface is therefore expected to be of great importance for lipid oxidation in emulsions. Previous studies have shown that e...... of this study was therefore to compare lipid oxidation in 10% fish oil-in-water emulsions prepared by two different kinds of high pressure homogenizers i.e. a microfluidizer and a two valve high pressure homogenizer. Emulsions were made with equal droplet sizes, and with either 1% sodium caseinate or 1% whey...

  9. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  10. Characteristics of iron corrosion scales and water quality variations in drinking water distribution systems of different pipe materials.

    Science.gov (United States)

    Li, Manjie; Liu, Zhaowei; Chen, Yongcan; Hai, Yang

    2016-12-01

    Interaction between old, corroded iron pipe surfaces and bulk water is crucial to the water quality protection in drinking water distribution systems (WDS). Iron released from corrosion products will deteriorate water quality and lead to red water. This study attempted to understand the effects of pipe materials on corrosion scale characteristics and water quality variations in WDS. A more than 20-year-old hybrid pipe section assembled of unlined cast iron pipe (UCIP) and galvanized iron pipe (GIP) was selected to investigate physico-chemical characteristics of corrosion scales and their effects on water quality variations. Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Inductively Coupled Plasma (ICP) and X-ray Diffraction (XRD) were used to analyze micromorphology and chemical composition of corrosion scales. In bench testing, water quality parameters, such as pH, dissolved oxygen (DO), oxidation reduction potential (ORP), alkalinity, conductivity, turbidity, color, Fe(2+), Fe(3+) and Zn(2+), were determined. Scale analysis and bench-scale testing results demonstrated a significant effect of pipe materials on scale characteristics and thereby water quality variations in WDS. Characteristics of corrosion scales sampled from different pipe segments show obvious differences, both in physical and chemical aspects. Corrosion scales were found highly amorphous. Thanks to the protection of zinc coatings, GIP system was identified as the best water quality stability, in spite of high zinc release potential. It is deduced that the complicated composition of corrosion scales and structural break by the weld result in the diminished water quality stability in HP system. Measurement results showed that iron is released mainly in ferric particulate form. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream

    Science.gov (United States)

    Sakai, Sanae; Konno, Uta; Nakahara, Nozomi; Takaki, Yoshihiro; Saito, Yumi; Imachi, Hiroyuki; Tasumi, Eiji; Makabe, Akiko; Koba, Keisuke; Takai, Ken

    2016-01-01

    ABSTRACT Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (δ15NNO2− and δ18ONO2−, respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70°C by thermophilic Thaumarchaeota populations composed almost entirely of “Candidatus Nitrosocaldus.” The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25‰ to 32‰) and strongly suggests the oxidation of ammonia, not ammonium. The δ18O value of nitrite produced from ammonia oxidation varied with the δ18O value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70°C and pH ≥6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using δ18ONO2− in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments. IMPORTANCE Because ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying

  12. Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

    Directory of Open Access Journals (Sweden)

    Li Sun

    2017-01-01

    Full Text Available Exfoliation of oxide scales from high-temperature heating surfaces of power boilers threatened the safety of supercritical power generating units. According to available space model, the oxidation kinetics of two ferritic-martensitic steels are developed to predict in supercritical water at 400°C, 500°C, and 600°C. The iron diffusion coefficients in magnetite and Fe-Cr spinel are extrapolated from studies of Backhaus and Töpfer. According to Fe-Cr-O ternary phase diagram, oxygen partial pressure at the steel/Fe-Cr spinel oxide interface is determined. The oxygen partial pressure at the magnetite/supercritical water interface meets the equivalent oxygen partial pressure when system equilibrium has been attained. The relative error between calculated values and experimental values is analyzed and the reasons of error are suggested. The research results show that the results of simulation at 600°C are approximately close to experimental results. The iron diffusion coefficient is discontinuous in the duplex scale of two ferritic-martensitic steels. The simulation results of thicknesses of the oxide scale on tubes (T91 of final superheater of a 600 MW supercritical boiler are compared with field measurement data and calculation results by Adrian’s method. The calculated void positions of oxide scales are in good agreement with a cross-sectional SEM image of the oxide layers.

  13. The effect of interfacial microstructure on the lipid oxidation stability of oil-in-water emulsions.

    Science.gov (United States)

    Kargar, Maryam; Spyropoulos, Fotios; Norton, Ian T

    2011-05-15

    A novel approach to reduce lipid oxidation in oil-in-water emulsions has been taken and involves the manipulation of the emulsions' interfacial microstructure. Oil-in-water emulsions stabilised by sodium caseinate (CAS), Tween 20 and silica particles were prepared and their lipid oxidation stability was assessed over a week. Lipid oxidation was monitored by measuring the concentration of primary lipid oxidation product, using the peroxide value method and secondary lipid oxidation products formation were evaluated with the p-anisidine technique. Oil-phase volume fraction and emulsifier type both play key roles in influencing the rate of lipid oxidation. Decreasing the oil fraction from 30% to 5% was found to promote lipid oxidation as a result of an increase in the amount of pro-oxidant iron per gram of oil. It was further shown that, CAS in the continuous phase reduces lipid oxidation at pH 7 due to its metal chelating ability. In addition, the results show that, emulsions stabilised with silica particles (at pH 2) inhibit lipid oxidation to a greater extent than emulsions stabilised with surfactants alone. The present study demonstrates that emulsions' physical properties such as oil-phase volume fraction, droplet size and droplet interfacial microstructure are all formulation parameters that can be used to significantly reduce the rate of lipid oxidation. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. One-Dimensional Metal-Oxide Nanostructures for Solar Photocatalytic Water-Splitting

    Science.gov (United States)

    Wang, Fengyun; Song, Longfei; Zhang, Hongchao; Luo, Linqu; Wang, Dong; Tang, Jie

    2017-08-01

    Because of their unique physical and chemical properties, one-dimensional (1-D) metal-oxide nanostructures have been extensively applied in the areas of gas sensors, electrochromic devices, nanogenerators, and so on. Solar water-splitting has attracted extensive research interest because hydrogen generated from solar-driven water splitting is a clean, sustainable, and abundant energy source that not only solves the energy crisis, but also protects the environment. In this comprehensive review, the main synthesis methods, properties, and especially prominent applications in solar water splitting of 1-D metal-oxides, including titanium dioxide (TiO2), zinc oxide (ZnO), tungsten trioxide (WO3), iron oxide (Fe2O3), and copper oxide (CuO) are fully discussed.

  15. Emission of nitrous oxide (N[sub 2]O) from denitrificating wastewater treatment plants. Die Emission von Lachgas (N[sub 2]O) in denitrifizierenden Belebungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Schulthess, R. von.

    1994-01-01

    The human intrusion in the nitrogen cycle has reached a dimension that disturbs its natural balance. As nitrogen is the growth limiting factor of algae in the sea, the epidemic occurrences of algae in the North- und East Sea in the last years are explained by the increased impact of nitrogen. Switzerland is among other countries responsible for the nitrogen pollutant of the North Sea. Therefore, nitrogen removal (denitrification) has to be incorporated into waste water treatment within the next years. Denitrification is the microbiological reduction of nitrate to elementary nitrogen. Nitrite, nitric oxide and nitrous oxide are intermediate product of this process. Nitrous oxide affects the global climate as a greenhouse gas and via chemical destruction of the ozone layer. Therefore, the waste water treatment plants must operate with a minimum of nitrous oxide emission. The goal of this work was to estimate the N[sub 2]O emission of waste water treatment plants, to identify critical operating conditions and to determine the main mechanisms of the emission. Batch experiments in a bench scale reactor were performed in which under controlled conditions all involved nitrogen species could be analysed. It could be seen that under normal operating conditions no significant amount of nitrous oxide is emitted. However, high nitrite conditions and low oxygen concentrations favour the emission of N[sub 2]O but not of nitric oxide. With a mathematical model that includes the reduction of nitrate, nitrite and nitrous oxide, segments of the experiments can be described satisfactorily. By including the enzyme synthesis and decay of denitrification enzymes in the model the whole experiments can be described. Even when the kinetic parameters could not be determined precisely, some general conclusions could be drawn. (author) figs., tabs., refs.

  16. Static SIMS and XPS study of water plasma exposed tin oxide films

    Science.gov (United States)

    Tarlov, Michael J.; Evans, John F.; Newman, John G.

    1993-02-01

    Static secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) were used to examine sputter-deposited tin oxide surfaces that were air-exposed, treated in a low-power water plasma, and annealed to 825 K in vacuum. The plasma reactor was appended directly to the surface analytical system, thus sample exposure to atmosphere was avoided. Water plasma treatment of the air-exposed films results in the removal of all XPS detectable carbon contamination while leaving the surface in hydrated and hydroxylated state. The static SIMS results coupled with XPS O(1s) data indicate that H -, OH -, H 2O +, and SnOH + secondary ion intensities are sensitive to the concentration of surface hydroxyl groups and water. SnOH + yields are shown to be enhanced by the presence of molecularly adsorbed water, suggesting that water is directly involved in the formation of SnOH + species. Annealing of water plasma treated tin oxide films in vacuum results in the loss of molecularly adsorbed water and surface dehydroxylation. The secondary ion ratios of H -/O -, OH -/ O -, H 2O +/Sn +, and SnOH +/Sn + can be used to monitor the thermally induced dehydration and dehydroxylation of the tin oxide surface. In addition, changes in the oxide surface the thermally induced dehydration and dehydroxylation of the tin oxide surface. In addition, changes in the tin oxide surface electronic structure are shown to strongly modulate both relative and absolute ion yields.

  17. The Manipulation of Hydrophobicity in Catalyst Design for Applications of Aerobic Alcohols Oxidation and Electrocatalytic Water Oxidation

    KAUST Repository

    Chen, Batian

    2016-05-17

    Hydrophobicity is the generalized characteristic of non-polar substances that brings about their exclusion from aqueous phases. This property, entropic in its nature, drives key self-assembly and phase separation processes in water. Protein folding, the formation of DNA double helix, the existence of lipid bilayers and the wetting properties of leaf surfaces are all due to hydrophobic interactions. Inspired by Nature, we aimed to use hydrophobicity for creating novel and improved catalytic systems. (I) A number of fluorous amphiphilic star block-copolymers containing a tris(benzyltriazolylmethyl)amine motif have been prepared. These polymers assembled into well-defined nanostructures in water, and their mode of assembly could be controlled by changing the composition of the polymer. The polymers were used for enzyme-inspired catalysis of alcohol oxidation. (II) An enzyme-inspired catalytic system based on a rationally designed multifunctional surfactant was developed. The resulting micelles feature metal-binding sites and stable free radical moieties as well as fluorous pockets that attract and preconcentrate molecular oxygen. In the presence of copper ions, the micelles effect chemoselective aerobic alcohol oxidation under ambient conditions in water, a transformation that is challenging to achieve nonenzymatically. (III) Development of a facile means of photo/electrocatalytic water splitting is one of the main barriers to establishing of a solar hydrogen economy. Of the two half-reactions involved in splitting water into O2 and H2, water oxidation presents the most challenge due to its mechanistic complexity. A practical water oxidation catalyst must be highly active, yet inexpensive and indefinitely stable under harsh oxidative conditions. Here, I shall describe the synthesis of a library of molecular water oxidation catalysts based on the Co complex of tris(2-benzimidazolylmethyl)amine, (BimH)3. A wide range of catalysts differing in their electronic properties

  18. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    KAUST Repository

    Sun, Ke

    2015-03-11

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g). © 2015, National Academy of Sciences. All rights reserved.

  19. Fundamental studies of water oxidation at model hematite electrodes prepared by atomic layer deposition

    Science.gov (United States)

    Klahr, Benjamin M.

    An increasing global demand for energy, combined with an awareness of anthropogenic climate change, has recently fueled the search for abundant, carbon neutral energy sources. The sun offers an enormous amount of energy that is practically inexhaustible and well distributed across Earth. Thus, it is an ideal source for meeting our future energy needs in a carbon neutral fashion. This work focuses on using hematite and sunlight to oxidize water, which is the rate limiting step of splitting water into the energy dense fuel, hydrogen, and the byproduct, oxygen. Hematite is abundant, absorbs a large fraction of the solar spectrum and has an appropriately placed valence band for water oxidation. However, the often cited poor bulk properties, and slow charge transfer kinetics require large applied potentials to oxidize water. Atomic layer deposition (ALD) was utilized to deposit uniform thin films of hematite on transparent conductive substrates as model electrodes to better understand the nature of the limitations in the bulk and at the surface. Comparison of the oxidation of water to the oxidation of fast redox shuttles allowed for the separation of bulk and surface processes. A combination of electrochemical impedance spectroscopy, photoelectrochemical and electrochemical measurements were employed to determine the cause of the large required applied potential. It was found that photogenerated holes initially oxidize the electrode surface under water oxidation conditions, which is attributed to the first step in water oxidation. A critical number of these surface intermediates need to be generated in order for subsequent hole-transfer steps to proceed. At low applied potentials, these intermediates are subject to recombination from the large concentration of electrons in the conduction band due to low band bending. At higher applied potentials, high band bending eliminates surface recombination and the charge collection efficiency of the electrolyte reaches unity. A

  20. The reaction of monochloramine and hydroxylamine: implications for ammonia–oxidizing bacteria in chloraminated drinking water

    Science.gov (United States)

    Drinking water chloramine use may promote ammonia–oxidizing bacteria (AOB) growth because of naturally occurring ammonia, residual ammonia remaining from chloramine formation, and ammonia released from chloramine decay and demand. A rapid chloramine residual loss is often associa...

  1. Assessment of supercritical water oxidation system testing for the Blue Grass Chemical Agent Destruction Pilot Plant

    National Research Council Canada - National Science Library

    Board on Army Science and Technology; Division on Engineering and Physical Sciences; National Research Council

    2013-01-01

    "Assessment of Supercritical Water Oxidation System Testing for the Blue Grass Chemical Agent Destruction Pilot Plant reviews and evaluates the results of the tests conducted on one of the SCWO units...

  2. Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Justine P. [Johns Hopkins Univ., Baltimore, MD (United States)

    2015-03-03

    Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

  3. The emulsifying and tribological properties of modified graphene oxide in oil-in-water emulsion

    NARCIS (Netherlands)

    Wu, Yinglei; Zeng, Xiangqiong; Ren, Tianhui; de Vries, Erik G.; van der Heide, Emile

    2017-01-01

    Graphene oxide (GO) was asymmetric chemically modified with myristyltrimethylammonium bromide (TTAB) to get modified graphene oxide (MGO). This MGO was used as an emulsifier and additive in oil-in-water emulsion. The emulsifying tests showed MGO greatly improved the stability of base emulsion and

  4. Photocatalytic Oxidation in Drinking Water Treatment Using Hypochlorite and Titanium Dioxide

    NARCIS (Netherlands)

    El-Kalliny, A.S.M.

    2013-01-01

    The main focus of this thesis is to study the advanced oxidation processes (AOPs) of water pollutants via UV/hypochlorite (homogeneous AOPs), and UV solar light/TiO2 (heterogeneous AOPs) in which the highly oxidative hydroxyl radicals (•OH) are produced. These radicals are capable of destructing the

  5. Gold-Catalyzed Aerobic Oxidation of 5-Hydroxymethylfurfural in Water at Ambient Temperature

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Woodley, John

    2009-01-01

    The aerobic oxidation of 5-hydroxymethylfurfural, a versatile biomass-derived chemical, is examined in water with a titania-supported gold-nanoparticle catalyst at ambient temperature (30 degrees C). The selectivity of the reaction towords 2,5-furandicarboxylic acid and the intermediate oxidation...

  6. Organosilane oxidation by water catalysed by large gold nanoparticles in a membrane reactor

    NARCIS (Netherlands)

    Gitis, V.; Beerthuis, R.; Shiju, N.R.; Rothenberg, G.

    2014-01-01

    We show that gold nanoparticles catalyse the oxidation of organosilanes using water as oxidant at ambient conditions. Remarkably, monodispersions of small gold particles (3.5 nm diameter) and large ones (6-18 nm diameter) give equally good conversion rates. This is important because separating large

  7. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts

    NARCIS (Netherlands)

    van Oversteeg, Christina H M; Doan, Hoang Q; de Groot, Frank M F; Cuk, Tanja

    2016-01-01

    X-ray absorption studies of the geometric and electronic structure of primarily heterogeneous Co, Ni, and Mn based water oxidation catalysts are reviewed. The X-ray absorption near edge and extended X-ray absorption fine structure studies of the metal K-edge, characterize the metal oxidation state,

  8. Effects of temperature on nitrous oxide (N2O) emission from intensive aquaculture system.

    Science.gov (United States)

    Paudel, Shukra Raj; Choi, Ohkyung; Khanal, Samir Kumar; Chandran, Kartik; Kim, Sungpyo; Lee, Jae Woo

    2015-06-15

    This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Ammonia-Oxidizing Archaea and Bacteria Differentially Contribute to Ammonia Oxidation in Sediments from Adjacent Waters of Rushan Bay, China

    Directory of Open Access Journals (Sweden)

    Hui He

    2018-02-01

    Full Text Available Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Ammonia-oxidizing archaea (AOA and bacteria (AOB are the key contributors to ammonia oxidation, and their relative contribution to this process is one of the most important issues related to the nitrogen cycle in the ocean. In this study, the differential contributions of AOA and AOB to ammonia oxidation in surface sediments from adjacent waters of Rushan Bay were studied based on the ammonia monooxygenase (amoA gene. Molecular biology techniques were used to analyze ammonia oxidizers’ community characteristics, and potential nitrification incubation was applied to understand the ammonia oxidizers’ community activity. The objective was to determine the community structure and activity of AOA and AOB in surface sediments from adjacent waters of Rushan Bay and to discuss the different contributions of AOA and AOB to ammonia oxidation during summer and winter seasons in the studied area. Pyrosequencing analysis revealed that the diversity of AOA was higher than that of AOB. The majority of AOA and AOB clustered into Nitrosopumilus and Nitrosospira, respectively, indicating that the Nitrosopumilus group and Nitrosospira groups may be more adaptable in studied sediments. The AOA community was closely correlated to temperature, salinity and ammonium concentration, whereas the AOB community showed a stronger correlation with temperature, chlorophyll-a content (chla and nitrite concentration. qPCR results showed that both the abundance and the transcript abundance of AOA was consistently greater than that of AOB. AOA and AOB differentially contributed to ammonia oxidation in different seasons. AOB occupied the dominant position in mediating ammonia oxidation during summer, while AOA might play a dominant role in ammonia oxidation during winter.

  10. Biological efficacy and toxic effect of emergency water disinfection process based on advanced oxidation technology.

    Science.gov (United States)

    Tian, Yiping; Yuan, Xiaoli; Xu, Shujing; Li, Rihong; Zhou, Xinying; Zhang, Zhitao

    2015-12-01

    An innovative and removable water treatment system consisted of strong electric field discharge and hydrodynamic cavitation based on advanced oxidation technologies was developed for reactive free radicals producing and waterborne pathogens eliminating in the present study. The biological efficacy and toxic effects of this advanced oxidation system were evaluated during water disinfection treatments. Bench tests were carried out with synthetic microbial-contaminated water, as well as source water in rainy season from a reservoir of Dalian city (Liaoning Province, China). Results showed that high inactivation efficiency of Escherichia coli (>5 log) could be obtained for synthetic contaminated water at a low concentration (0.5-0.7 mg L(-1)) of total oxidants in 3-10 s. The numbers of wild total bacteria (108 × 10(3) CFU mL(-1)) and total coliforms (260 × 10(2) MPN 100 mL(-1)) in source water greatly reduced to 50 and 0 CFU mL(-1) respectively after treated by the advanced oxidation system, which meet the microbiological standards of drinking water, and especially that the inactivation efficiency of total coliforms could reach 100%. Meanwhile, source water qualities were greatly improved during the disinfection processes. The values of UV254 in particular were significantly reduced (60-80%) by reactive free radicals. Moreover, the concentrations of possible disinfection by-products (formaldehyde and bromide) in treated water were lower than detection limits, indicating that there was no harmful effect on water after the treatments. These investigations are helpful for the ecotoxicological studies of advanced oxidation system in the treatments of chemical polluted water or waste water. The findings of this work suggest that the developed water treatment system is ideal in the acute phases of emergencies, which also could offer additional advantages over a wide range of applications in water pollution control.

  11. Influence of formulation on the oxidative stability of water-in-oil emulsions.

    Science.gov (United States)

    Dridi, Wafa; Essafi, Wafa; Gargouri, Mohamed; Leal-Calderon, Fernando; Cansell, Maud

    2016-07-01

    The oxidation of water-in-oil (W/O) emulsions was investigated, emphasizing the impact of compositional parameters. The emulsions had approximately the same average droplet size and did not show any physical destabilization throughout the study. In the absence of pro-oxidant ions in the aqueous phase, lipid oxidation of the W/O emulsions was moderate at 60°C and was in the same range as that measured for the neat oils. Oxidation was significantly promoted by iron encapsulation in the aqueous phase, even at 25°C. However, iron chelation reduced the oxidation rate. Emulsions based on triglycerides rich in polyunsaturated fatty acids were more prone to oxidation, whether the aqueous phase encapsulated iron or not. The emulsions were stabilized by high- and low-molecular weight surfactants. Increased relative fractions of high molecular weight components reduced the oxidation rate when iron was present. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Hydrothermal Synthesis of Metal Oxide Nanoparticles in Supercritical Water

    National Research Council Canada - National Science Library

    Hayashi, Hiromichi; Hakuta, Yukiya

    2010-01-01

    .... Supercritical water allows control of the crystal phase, morphology, and particle size since the solvent's properties, such as density of water, can be varied with temperature and pressure, both...

  13. Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

    Science.gov (United States)

    de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

    2011-11-01

    Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Fourier transform infrared difference spectroscopy for studying the molecular mechanism of photosynthetic water oxidation

    Directory of Open Access Journals (Sweden)

    Hsiu-An eChu

    2013-05-01

    Full Text Available The photosystem II reaction center mediates the light-induced transfer of electrons from water to plastoquinone, with concomitant production of O2. Water oxidation chemistry occurs in the oxygen-evolving complex (OEC, which consists of an inorganic Mn4CaO5 cluster and its surrounding protein matrix. Light-induced Fourier transform infrared (FTIR difference spectroscopy has been successfully used to study the molecular mechanism of photosynthetic water oxidation. This powerful technique has enabled the characterization of the dynamic structural changes in active water molecules, the Mn4CaO5 cluster, and its surrounding protein matrix during the catalytic cycle. This mini-review presents an overview of recent important progress in FTIR studies of the OEC and implications for revealing the molecular mechanism of photosynthetic water oxidation.

  15. Efficient electrochemical water oxidation in neutral and near-neutral systems by nanoscale silver-oxide catalyst

    KAUST Repository

    Joya, Khurram Saleem

    2016-07-19

    In electrocatalytic water splitting systems pursuing for renewable energy using sun light, developing robust, stable and easy accessible materials operating under mild chemical conditions is pivotal. We present here unique nano-particulate type silver-oxide (AgOx-NP) based robust and highly stable electrocatalyst for efficient water oxidation. The AgOx-NP is generated in situ in a HCO3–/CO2 system under benign conditions. Mircographs show that they exhibit nanoscale box type squared nano-bipyramidal configuration. The oxygen generation is initiated at low overpotential, and a sustained O2 evolution current density of > 1.1 mA cm–2 is achieved during prolonged-period water electrolysis. The AgOx-NP electrocatalyst performs exceptionally well in metal-ions free neutral or near-neutral carbonate, phosphate and borate buffers relative to recently reported Co-oxide and Ni-oxide based heterogeneous electrocatalysts, which are unstable in metal-ions free electrolyte and tend to degrade with time and lose catalytic performance during long-term experimental tests.

  16. Water transport confined in graphene oxide channels through the rarefied effect.

    Science.gov (United States)

    Chen, Bo; Jiang, Haifeng; Liu, Xiang; Hu, Xuejiao

    2018-02-21

    Understanding the mechanism of water transport inside an interlayer between graphene-based plates has tremendous value for theoretical studies and industrial applications. The fluid flow confined in nano-scaled spaces experiences a slip velocity near the wall, which is significantly different to that of bulk water. Here we propose a model combining classic hydrodynamics with kinetic theory to depict the dependency of the slip effect on the oxide concentration of valley plates. The influence of oxidized graphene on water flow is a comprehensive result of a slipped boundary, and depends on both the diffuse reflection coefficient of the wall, and the shrunken effective passageway caused by the electrostatic interactions between the oxidized surface and the water molecules. The former effect enhances the water flow, which reduces with increasing oxide concentration, while the latter effect inhibits water flow. We examine the diffuse reflection coefficient and the shrunken effective passageway at different oxide concentrations of the GO sheets by molecular dynamics simulations, and we quantitively predict the flux relationship at various concentrations. This work provides a molecular insight into transport processes of confined water and a useful guideline for the design of perfect graphene-derived membranes for desalination.

  17. Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes.

    Science.gov (United States)

    Doyle, Richard L; Godwin, Ian J; Brandon, Michael P; Lyons, Michael E G

    2013-09-07

    This paper presents a review of the redox and electrocatalytic properties of transition metal oxide electrodes, paying particular attention to the oxygen evolution reaction. Metal oxide materials may be prepared using a variety of methods, resulting in a diverse range of redox and electrocatalytic properties. Here we describe the most common synthetic routes and the important factors relevant to their preparation. The redox and electrocatalytic properties of the resulting oxide layers are ascribed to the presence of extended networks of hydrated surface bound oxymetal complexes termed surfaquo groups. This interpretation presents a possible unifying concept in water oxidation catalysis - bridging the fields of heterogeneous electrocatalysis and homogeneous molecular catalysis.

  18. Time resolved study of hydroxyl radical oxidation of oleic acid at the air-water interface

    Science.gov (United States)

    Zhang, Xinxing; Barraza, Kevin M.; Upton, Kathleen T.; Beauchamp, J. L.

    2017-09-01

    The ubiquity of oleic acid (OA) renders it a poster child for laboratory investigations of environmental oxidation chemistry. In the current study, mechanistic details of the oxidation of OA by hydroxyl radicals at the air-water interface are investigated using field-induced droplet ionization mass spectrometry (FIDI-MS). Products from OH oxidation of both unsaturated and saturated carbon atoms are identified, and mechanisms for both types of oxidation processes are proposed. Uptake of oxygen in the interfacial layer increases linearly with time, consistent with Langmuir-Hinshelwood reaction kinetics. These results provide fundamental knowledge relating to OH initiated degradation of fatty acids in atmospheric aerosols.

  19. Scalable Synthesis of Efficient Water Oxidation Catalysts: Insights into the Activity of Flame-Made Manganese Oxide Nanocrystals.

    Science.gov (United States)

    Liu, Guanyu; Hall, Jeremy; Nasiri, Noushin; Gengenbach, Thomas; Spiccia, Leone; Cheah, Mun Hon; Tricoli, Antonio

    2015-12-21

    Chemical energy storage by water splitting is a promising solution for the utilization of renewable energy in numerous currently impracticable needs, such as transportation and high temperature processing. Here, the synthesis of efficient ultra-fine Mn3O4 water oxidation catalysts with tunable specific surface area is demonstrated by a scalable one-step flame-synthesis process. The water oxidation performance of these flame-made structures is compared with pure Mn2O3 and Mn5O8, obtained by post-calcination of as-prepared Mn3O4 (115 m(2)  g(-1)), and commercial iso-structural polymorphs, probing the effect of the manganese oxidation state and synthetic route. The structural properties of the manganese oxide nanoparticles were investigated by XRD, FTIR, high-resolution TEM, and XPS. It is found that these flame-made nanostructures have substantially higher activity, reaching up to 350 % higher surface-specific turnover frequency (0.07 μmolO2  m(-2)  s(-1)) than commercial nanocrystals (0.02 μmolO2  m(-2)  s(-1)), and production of up to 0.33 mmolO2  molMn (-1)  s(-1). Electrochemical characterization confirmed the high water oxidation activity of these catalysts with an initial current density of 10 mA cm(-2) achieved with overpotentials between 0.35 and 0.50 V in 1 m NaOH electrolyte. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water

    Science.gov (United States)

    van der Grift, B.; Rozemeijer, J. C.; Griffioen, J.; van der Velde, Y.

    2014-06-01

    The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from groundwater to surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and ditch water, we investigated Fe(II) oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II) by O2. Seasonal changes in climatic conditions affected the Fe(II) oxidation process. Lower pH and lower temperatures in winter (compared to summer) resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than one week before complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilisation of dissolved P during the initial stage of the Fe(II) oxidation proces which results in P-depleted water before Fe(II) is competly depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox gradients seems an

  1. Comparision of photocatalysis and photolysis processes for arsenic oxidation in water.

    Science.gov (United States)

    Fontana, Klaiani B; Lenzi, Giane G; Seára, Eriton C R; Chaves, Eduardo S

    2018-01-11

    The oxidation of As(III) to As(V) in aqueous solution was evaluated using heterogeneous photocatalysis and photolysis. The influence of TiO 2 as catalyst in different crystalline (rutile, anatase) and commercial forms was evaluated in a batch reactor and an insignificant difference was observed between them. The process by photocatalysis reached up to 97% As(III) oxidation and no significant difference was observed comparing to results obtained by photolysis. The photolysis experiments (UV radiation only), also carried out in a batch system, showed a high oxidation rate of As(III) (90% in 20min). The influence of different matrices (well water, river water and public water supply) were evaluated. Additionally, the effect of As(V) concentration, generated during the oxidation process, was studied. Continuous photolysis experiments using only UV radiation were performed, resulting in a high As(III) oxidation rate. Using a flow rate of 5mLmin -1 and an initial concentration of As(III) 200µgL -1 , gave an oxidation percentage of As(III) of up to 72%, showing a simple and economical alternative to the oxidation step of As(III) to As(V) in the treatment of water contaminated with arsenic. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Heterogeneous Photo-Fenton Reaction Catalyzed by Nanosized Iron Oxides for Water Treatment

    Directory of Open Access Journals (Sweden)

    Chuan Wang

    2012-01-01

    Full Text Available Great efforts have been exerted in overcoming the drawbacks of the Fenton reaction for water treatment applications. The drawbacks include pH confinement, handling of iron sludge, slow regeneration of Fe(II, and so forth. This paper highlights the recent developments in the heterogeneous photo-Fenton reaction which utilizes nanosized iron oxides as catalyst for maximizing the activity due to the enhanced physical or chemical properties brought about by the unique structures. This paper also summarizes the fundamentals of the Fenton reaction, which determine the inherent drawbacks and associated advances, to address the advantages of iron oxides and nanosized iron oxides. Tips for applying this method in water treatment are also provided. Given that the environmental effect of nanosized iron oxides is not yet well established, rapid research growth may occur in the near future to advance this promising technology toward water treatment once it is smartly coupled with conventional technologies.

  3. Strain-Induced Water Dissociation on Supported Ultrathin Oxide Films

    CERN Document Server

    Song, Zhenjun; Xu, Hu

    2015-01-01

    Controlling the dissociation of single water molecule on an insulating surface plays a crucial role in many catalytic reactions. In this Letter, we have identified the enhanced chemical reactivity of ultrathin MgO(100) films deposited on Mo(100) substrate that causes water dissociation. We reveal that the ability to split water on insulating surface closely depends on the lattice mismatch between ultrathin films and the underlying substrate, and substrate-induced in-plane tensile strain dramatically results in water dissociation on MgO(100). Three dissociative adsorption configurations of water with lower energy are predicted, and the structural transition going from molecular form to dissociative form is almost barrierless. Our results provide an effective avenue to achieve water dissociation at the single-molecule level and shed light on how to tune the chemical reactions of insulating surfaces by choosing the suitable substrates.

  4. Significant role of Mn(III) sites in e(g)(1) configuration in manganese oxide catalysts for efficient artificial water oxidation.

    Science.gov (United States)

    Indra, Arindam; Menezes, Prashanth W; Schuster, Felix; Driess, Matthias

    2015-11-01

    Development of efficient bio-inspired water oxidation system with transition metal oxide catalyst has been considered as the one of the most challenging task in the recent years. As the oxygen evolving center of photosystem II consists of Mn4CaO5 cluster, most of the water oxidation study was converged to build up manganese oxide based catalysts. Here we report the synthesis of efficient artificial water oxidation catalysts by transferring the inactive manganese monooxide (MnO) under highly oxidizing conditions with ceric ammonium nitrate (CAN) and ozone (O3). MnO was partially oxidized to form mixed-valent manganese oxide (MnOx) with CAN whereas completely oxidized to mineral phase of ε-MnO2 (Akhtenskite) upon treatment of O3 in acidic solution, which we explore first time as a water oxidation catalyst. Chemical water oxidation, as well as the photochemical water oxidation in the presence of sacrificial electron acceptor and photosensitizer with the presented catalysts were carried out that followed the trends: MnOx>MnO2>MnO. Structural and activity correlation reveals that the presence of larger extent of Mn(III) in MnOx is the responsible factor for higher activity compared to MnO2. Mn(III) species in octahedral system with eg(1) configuration furnishes and facilitates the Mn-O and Mn-Mn bond enlargement with required structural flexibility and disorder in the manganese oxide structure which indeed facilitates water oxidation. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Effect of tolvaptan on renal water and sodium excretion and blood pressure during nitric oxide inhibition

    DEFF Research Database (Denmark)

    Therwani, Safa Al; Rosenbæk, Jeppe Bakkestrøm; Mose, Frank Holden

    2017-01-01

    BACKGROUND: Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron's principal cells. In a dose-response study, we measured the effect of tolvaptan on renal handling of water and sodium and sy...

  6. Co-doped titanium oxide foam and water disinfection device

    Science.gov (United States)

    Shang, Jian-Ku; Wu, Pinggui; Xie, Rong-Cai

    2016-01-26

    A quaternary oxide foam, comprises an open-cell foam containing (a) a dopant metal, (b) a dopant nonmetal, (c) titanium, and (d) oxygen. The foam has the advantages of a high surface area and a low back pressure during dynamic flow applications. The inactivation of Escherichia coli (E. coli) was demonstrated in a simple photoreactor.

  7. Removal of arsenic from drinking water by chemical precipitation--a modeling and simulation study of the physical-chemical processes.

    Science.gov (United States)

    Pal, Parimal; Ahammad, Sk Ziauddin; Pattanayak, Abhinandan; Bhattacharya, Pinaki

    2007-04-01

    A dynamic mathematical model was developed for removal of arsenic from drinking water by chemical coagulation-precipitation and was validated experimentally in a bench-scale set-up. While examining arsenic removal efficiency of the scheme under different operating conditions, coagulant dose, pH and degree of oxidation were found to have pronounced impact. Removal efficiency of 91-92% was achieved for synthetic feed water spiked with 1 mg/L arsenic and pre-oxidized by potassium permanganate at optimum pH and coagulant dose. Model predictions corroborated well with the experimental findings (the overall correlation coefficient being 0.9895) indicating the capability of the model in predicting performance of such a treatment plant under different operating conditions. Menu-driven, user-friendly Visual Basic software developed in the study will be very handy in quick performance analysis. The simulation is expected to be very useful in full-scale design and operation of the treatment plants for removal of arsenic from drinking water.

  8. Improving the oxidation resistance of 316L stainless steel in simulated pressurized water reactor primary water by electropolishing treatment

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guangdong [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); Lu, Zhanpeng, E-mail: zplu@shu.edu.cn [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China); State Key Laboratory of Advanced Special Steels, Shanghai University, Shanghai, 200072 (China); Ru, Xiangkun; Chen, Junjie; Xiao, Qian; Tian, Yongwu [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai, 200072 (China)

    2015-12-15

    The oxidation behavior of 316L stainless steel specimens after emery paper grounding, mechanical polishing, and electropolishing were investigated in simulated pressurized water reactor primary water at 310 °C for 120 and 500 h. Electropolishing afforded improved oxidation resistance especially during the early immersion stages. Duplex oxide films comprising a coarse Fe-rich outer layer and a fine Cr-rich inner layer formed on all specimens after 500 h of immersion. Only a compact layer was observed on the electropolished specimen after 120 h of immersion. The enrichment of chromium in the electropolished layer contributed to the passivity and protectiveness of the specimen. - Highlights: • Duplex oxide films on ground and mechanically polished specimens. • Compact oxide on electropolished specimen after 120 h immersion. • Large spinel outer layer rich in Fe and fine spinel inner layer rich in Cr. • Electropolishing improved oxidation resistance especially at the early stages. • Inhomogeneous Cr-rich inner layer with granular areas affected by surface treatment.

  9. Report on the research cooperation promoting project in fiscal 1998. Research cooperation related to the mine waste water treatment technology utilizing biomass; 1998 nendo kenkyu kyoryoku suishin jigyo hokokusho. Bio riyo ni yoru kohaisui shori gijutsu ni kansuru kyoryoku

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    This paper describes the achievement in relation with the mine waste water treatment technology utilizing biomass, from among the promotion projects for research cooperation with China. Waste water is converted into ferric iron (Fe{sup 3+}), which precipitates at low pH, by utilizing iron oxidizing bacteria which use ferrous iron (Fe{sup 2+}) in the waste water as the energy source, and is precipitated and removed by using low-cost calcium carbonate as a neutralizing agent. Fiscal 1998 has performed eight site surveys with 47 persons in total. The main survey items are the study and guidance of pilot plant operation and the survey on measures to prevent occurrence of contamination by heavy metals in Wushan Mine. Additional site surveys were made at Dexing Mine and Yinshan Lead/Zinc Mine. Continued from fiscal 1997, consumables required for the pilot plant were purchased, and items of the bench-scale testing equipment used by Japan for domestic researches (an oxidation and neutralization testing equipment and a copper recovering and testing equipment) were transported to China. The operation research data of the pilot plant were put in order and analyzed. This paper summarizes the concept design of the shaft waste water treatment facilities for the north mine in Wushan Mine, and the surveys on measures for heavy metal contamination sources. (NEDO)

  10. Research cooperation project in fiscal 1998. General report on research cooperation related to mine waste water treatment technology by utilizing biotechnology; 1998 nendo kenkyu kyoryoku jigyo. Bio riyo ni yoru kohaisui shori gijutsu ni kansuru kenkyu kyoryoku sokatsu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    This paper describes cooperative development of bio-treatment technology for mine waste water generated by operating mines in China. Certain types of bacteria have capability to oxidize ferrous iron in the waste water into ferric iron ions. The bacteria cause ferric iron oxides in low pH regions to get deposited, and can remove them from sedimentation by using cheap calcium carbonate as a neutralizer. Volumetric reduction in waste sediments may also be achieved during removing heavy metals in a pretreatment process. Great advance may be expected in taking actions to prevent water quality contamination. This paper summarizes activities taken in fiscal 1998. Eight site surveys in total were carried out using 47 persons in total. Major activities included operation study guidance of a pilot plant, and surveys for measures on heavy metal generation sources in Wushan Mine. In addition, site surveys were performed at Dexing Mine and Yinshan Zinc Mine. Subsequently from fiscal 1997, a bench scale testing equipment used in Japan and consumables were transported to China. The operation study data on the pilot plant were put into order and analyzed. Concept design was also made on a waste water treatment facility for Wushan Mine. (NEDO)

  11. UV/H2O2 oxidation of arsenic and terbuthylazine in drinking water.

    Science.gov (United States)

    Sorlini, S; Gialdini, F; Stefan, M

    2014-02-01

    Arsenic is a widespread contaminant in the environment. The intake of water containing high concentrations of arsenic could have serious impact on human health, such as skin and lung cancer. In the European Union, thus, also in Italy, the arsenic limit in drinking water is 10 μg L(-1). Several water remediation treatment technologies are available for arsenic removal. For some processes, the removal efficiencies can be improved after an oxidation step. Most full-scale applications are based on conventional oxidation processes for chemical micropollutant removal. However, if water contains arsenic and refractory organic contaminants, the advanced oxidation processes could be considered. The aim of this work was to investigate the effectiveness of ultraviolet (UV) radiation alone and in combination with hydrogen peroxide for the oxidation of arsenic and terbuthylazine (TBA). The experimental tests were performed in groundwater at the laboratory scale (0.1 mg L(-1) As(III) and 10 μg L(-1) TBA). Hydrogen peroxide alone (15 mg L(-1)) was ineffective on both arsenic and TBA oxidation; the 253.7-nm radiation alone did not oxidize arsenic(III), but photolyzed efficiently TBA (52 % removal yield at a UV dose of 1,200 mJ cm(-2)). The UV/H2O2 advanced oxidation (UV dose 600-2,000 mJ cm(-2), 5-15 mg L(-1) H2O2) was the most effective process for the oxidation of both arsenic and TBA, with observed oxidation efficiencies of 85 and 94 %, respectively, with 5 mg L(-1) H2O2 and a UV dose of 2,000 mJ cm(-2).

  12. Manganese-oxidizing and -reducing microorganisms isolated from biofilms in chlorinated drinking water systems.

    Science.gov (United States)

    Cerrato, José M; Falkinham, Joseph O; Dietrich, Andrea M; Knocke, William R; McKinney, Chad W; Pruden, Amy

    2010-07-01

    The interaction of chemical, physical and biological factors that affect the fate, transport and redox cycling of manganese in engineered drinking water systems is not clearly understood. This research investigated the presence of Mn-oxidizing and -reducing bacteria in conventional water treatment plants exposed to different levels of chlorine. Mn(II)-oxidizing and Mn(IV)-reducing bacteria, principally Bacillus spp., were isolated from biofilm samples recovered from four separate drinking water systems. Rates of Mn-oxidation and -reduction for selected individual isolates were represented by pseudo-first-order kinetics. Pseudo-first-order rate constants were obtained for Mn-oxidation (range: 0.106-0.659 days(-1)), aerobic Mn-reduction (range: 0.036-0.152 days(-1)), and anaerobic Mn-reduction (range: 0.024-0.052 days(-1)). The results indicate that microbial-catalyzed Mn-oxidation and -reduction (aerobic and anaerobic) can take place simultaneously in aqueous environments exposed to considerable oxygen and chlorine levels and thus affect Mn-release and -deposition in drinking water systems. This has important implications for Mn-management strategies, which typically assume Mn-reduction is not possible in the presence of chlorine and oxidizing conditions. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. Water dispersal of methanotrophic bacteria maintains functional methane oxidation in Sphagnum mosses

    Directory of Open Access Journals (Sweden)

    Anuliina ePutkinen

    2012-01-01

    Full Text Available It is known that Sphagnum associated methanotrophy (SAM changes in relation to the peatland water table (WT level. After drought, rising WT is able to reactivate SAM. We aimed to reveal whether this reactivation is due to activation of indigenous methane (CH4 oxidizing bacteria (MOB already present in the mosses or to MOB present in water. This was tested through two approaches: In a transplantation experiment, Sphagna lacking SAM activity were transplanted into flark water next to Sphagna oxidizing CH4. Already after 3 d, most of the transplants showed CH4 oxidation activity. Microarray showed that the MOB community compositions of the transplants and the original active mosses had become more similar within 28 d thus indicating MOB movement through water between mosses. Methylocystis-related type II MOB dominated the community. In a following experiment, SAM inactive mosses were bathed overnight in non-sterile and sterile-filtered SAM active site flark water. Only mosses bathed with non-sterile flark water became SAM active, which was also shown by the pmoA copy number increase of over 60 times. Thus, it was evident that MOB present in the water can colonize Sphagnum mosses. This colonization could act as a resilience mechanism for peatland CH4 dynamics by allowing the re-emergence of CH4 oxidation activity in Sphagnum.

  14. A Robust Molecular Catalyst Generated In Situ for Photo- and Electrochemical Water Oxidation.

    Science.gov (United States)

    Younus, Hussein A; Ahmad, Nazir; Chughtai, Adeel H; Vandichel, Matthias; Busch, Michael; Van Hecke, Kristof; Yusubov, Mekhman; Song, Shaoxian; Verpoort, Francis

    2017-03-09

    Water splitting is the key step towards artificial photosystems for solar energy conversion and storage in the form of chemical bonding. The oxidation of water is the bottle-neck of this process that hampers its practical utility; hence, efficient, robust, and easy to make catalytic systems based on cheap and earth-abundant materials are of exceptional importance. Herein, an in situ generated cobalt catalyst, [Co II (TCA) 2 (H 2 O) 2 ] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently conducts photochemical water oxidation under near-neutral conditions is presented. The catalyst showed high stability under photolytic conditions for more than 3 h of photoirradiation. During electrochemical water oxidation, the catalytic system assembled a catalyst film, which proved not to be cobalt oxide/hydroxide as normally expected, but instead, and for the first time, generated a molecular cobalt complex that incorporated the organic ligand bound to cobalt ions. The catalyst film exhibited a low overpotential for electrocatalytic water oxidation (360 mV) and high oxygen evolution peak current densities of 9 and 2.7 mA cm -2 on glassy carbon and indium-doped tin oxide electrodes, respectively, at only 1.49 and 1.39 V (versus a normal hydrogen electrode), respectively, under neutral conditions. This finding, exemplified on the in situ generated cobalt complex, might be applicable to other molecular systems and suggests that the formation of a catalytic film in electrochemical water oxidation experiments is not always an indication of catalyst decomposition and the formation of nanoparticles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Effects of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing surfaces.

    Science.gov (United States)

    Liu, Chengchu; Duan, Jingyun; Su, Yi-Cheng

    2006-02-15

    The effects of electrolyzed oxidizing (EO) water on reducing Listeria monocytogenes contamination on seafood processing surfaces were studied. Chips (5 x 5 cm(2)) of stainless steel sheet (SS), ceramic tile (CT), and floor tile (FT) with and without crabmeat residue on the surface were inoculated with L. monocytogenes and soaked in tap or EO water for 5 min. Viable cells of L. monocytogenes were detected on all chip surfaces with or without crabmeat residue after being held at room temperature for 1 h. Soaking contaminated chips in tap water resulted in small-degree reductions of the organism (0.40-0.66 log cfu/chip on clean surfaces and 0.78-1.33 log cfu/chip on dirty surfaces). Treatments of EO water significantly (peffectiveness of EO water on inactivating Listeria cells. However, treatments of EO water also resulted in significant reductions of L. monocytogenes on dirty surfaces (2.33 log on SS and CT and 1.52 log on FT) when compared with tap water treatments. The antimicrobial activity of EO water was positively correlated with its chlorine content. High oxidation-reduction potential (ORP) of EO water also contributed significantly to its antimicrobial activity against L. monocytogenes. EO water was more effective than chlorine water on inactivating L. monocytogenes on surfaces and could be used as a chlorine alternative for sanitation purpose. Application of EO water following a thorough cleaning process could greatly reduce L. monocytogenes contamination in seafood processing environments.

  16. Spacecraft Water Regeneration by Catalytic Wet Air Oxidation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to develop advanced catalysts for a volatile removal assembly used to purify spacecraft water. The innovation of the proposed...

  17. Advanced Electrochemical Oxidation Cell for Purification of Water Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Vesitech, Inc. has developed a totally new class of water treatment technology utilizing novel carbon based electrodes that have been shown to electrochemically...

  18. Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

    KAUST Repository

    de Ruiter, J. M.

    2016-09-20

    One of the key challenges in designing light-driven artificial photosynthesis devices is the optimization of the catalytic water oxidation process. For this optimization it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the form [Ru(cy)(L)(H2O)](2+) (cy = p-cymene, L = 2,2\\'-bipyridine and its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques, and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using online electrochemical mass spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental spectra, as well as free energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified as the third PCET step, which involves O-O bond formation. The good agreement between the optical and thermodynamic data and DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterization of water oxidation catalysts and for the interpretation of experimental observables.

  19. Ligand exchange and redox processes in iridium triazolylidene complexes relevant to catalytic water oxidation.

    Science.gov (United States)

    Petronilho, Ana; Llobet, Antoni; Albrecht, Martin

    2014-12-15

    Iridium(III) complexes containing a bidentate spectator ligand have emerged as powerful catalyst precursors for water oxidation. Here we investigate the initial steps of the transformation at the iridium center when using complex [IrCp*(pyr-trz)Cl] 1 (Cp* = pentamethylcyclopentadienyl, pyr-trz = 4-(2-pyridyl)-1,2,3-triazol-5-ylidene), a potent water oxidation catalyst precursor. Ligand exchange with water is facile and is reversed in the presence of chloride ions, while MeCN substitution is effective only from the corresponding aqua complex. A pKa of 8.3 for the aqua complex was determined, which is in agreement with strong electron donation from the triazolylidene ligand that is comparable to aryl anions. Evaluation of the pH-dependent oxidation process in aqueous media reveals two regimes (pH 4-8.5 and above pH 10.5) where proton-coupled electron transfer processes occur. These investigations will help to further optimize water oxidation catalysts and indicate that MeCN as a cosolvent has adverse effects for initiating water coordination in the oxidation process.

  20. The anti-aging and anti-oxidation effects of tea water extract in Caenorhabditis elegans.

    Science.gov (United States)

    Fei, Tianyi; Fei, Jian; Huang, Fang; Xie, Tianpei; Xu, Jifeng; Zhou, Yi; Yang, Ping

    2017-10-15

    Tea includes puer tea, black tea, green tea and many others. By using model organism Caenorhabditis elegans, the anti-aging and anti-oxidation effects of tea water extract were systemically examined in this study. We found that water extract of puer tea, black tea and green tea all increased the lifespan of worms, postponed Aβ-induced progressive paralysis in Alzheimer's disease transgenic worms, and improved the tolerance of worms to the oxidative stress induced by heavy metal Cr6+. Moreover, the anti-oxidation effects of tea water extract at low concentration were different among 4 kinds of brands of green tea. The underlying mechanisms were further explored using genetically manipulated-mutant worms. The anti-oxidative stress effects of green tea water extract depend on the dietary restriction and germline signaling pathways, but not the FOXO and mitochondrial respiratory chain signals. Therefore, tea water extract provides benefits of anti-aging, anti-AD and anti-oxidation. Copyright © 2017. Published by Elsevier Inc.

  1. The production of magnetic nanoparticles of Iron Oxide by arc discharge in water

    Science.gov (United States)

    Yousefi, Hamid Reza; Fathollah, Sara; Nikeyn, Maryam; Khatami, Shohreh

    2012-10-01

    Nanoparticles can be utilized for any practical application. In recent years; considerable attention has been paid to iron oxide magnetic. Iron oxide nanoparticles are the class of nanoparticle which can have useful magnetic properties. In this research, magnetic iron oxide nanoparticles were produced by Arc discharge method in water. Structural analysis carried out by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Spectrophotometer. Various magnetic nanoparticles like iron carbide (Fe3c), magnetic iron oxide (magnetite /maghemite) are obtained by arc discharge method in water. In this work have been showed, the influence of the time duration on the number of magnetic nanoparticles and the influence of the gap between the two electrodes on particle structure and size distribution. Furthermore, when iron nanoparticles are used under applied magnetic field, the particles would move in the direction of magnetic field. When the magnetic field is removed, the particles stop moving and still remain stably suspend in the dielectric liquid.

  2. Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview).

    Energy Technology Data Exchange (ETDEWEB)

    Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodriguez, J.

    2008-03-18

    The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.

  3. Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview).

    Energy Technology Data Exchange (ETDEWEB)

    Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodgriguez, J.

    2008-03-18

    The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.

  4. Treatment of sewage sludge in supercritical water and evaluation of the combined process of supercritical water gasification and oxidation.

    Science.gov (United States)

    Qian, Lili; Wang, Shuzhong; Xu, Donghai; Guo, Yang; Tang, Xingying; Wang, Longfei

    2015-01-01

    Influences of temperature and oxidation coefficient (n) on sewage sludge treatment in supercritical water and its corresponding reaction mechanism were studied. Moreover, the combined process of supercritical water gasification (SCWG) and supercritical water oxidation (SCWO) was also investigated. The results show that ammonia nitrogen, phenols and pyridines are main refractory intermediates. The weight of solid products at 873K and n=4 is only 3.5wt.% of the initial weight, which is lower than that after combustion. Volatile organics in solid phase have almost released at 723K and n=0. Highest yield of combustible gases was obtained at n=0, and H2 yield can reach 11.81mol/kg at 873K. Furthermore, the combination of SCWG at 723K and SCWO at 873K with a total n=1 is feasible for its good effluent quality and low operation costs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Oxidation of the antibacterial agent norfloxacin during sodium hypochlorite disinfection of marine culture water.

    Science.gov (United States)

    Zhang, Yuanyuan; Rong, Chuan; Song, Yanqun; Wang, Yinghui; Pei, Jiying; Tang, Xinying; Zhang, Ruijie; Yu, Kefu

    2017-09-01

    Chlorination disinfection and antibiotic addition are two universal processes of marine culture. The generation of disinfection byproducts (DBPs) is unavoidable. Antibiotic residue not only pollutes water but also acts as a precursor to the production of new DBPs. The fate of antibiotic norfloxacin (NOR) in chlorination disinfection was investigated. It was observed that NOR could be oxidized by disinfection agent sodium hypochlorite, but the oxidation rate varied considerably with the type of disinfected water. For fresh water, marine culture water and sea water, the reaction rate constant was 0.066 min(-1), 0.466 min(-1) and 1.241 min(-1), respectively. The difference was primarily attributed to the promotion role of bromide ions in seawater and marine culture water. Moreover, the bromide ions could result in the generation of brominated DBPs (Br-DBPs). The kinetics, products, reaction centers and mechanisms were investigated. The active site of NOR was found to be the N4 atom on piperazinyl in fresh water. During marine culture water and sea water disinfection, the carboxyl on NOR was oxidized and two Br-DBPs were formed. This was attributed to the lowering of the reaction's required activation energy when performed in the presence of bromide ions. The Br-DBPs were also confirmed in real shrimp pond brackish water. Quantitative structure activity relationships and the total organic halogen analysis showed that the DBPs in marine culture water possessed stronger toxicological properties than the DBPs in fresh water. The toxicity increase was attributed to the production of Br-DBPs in the disinfection process of marine culture water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine-Periodic Mesoporous Organosilica.

    Science.gov (United States)

    Liu, Xiao; Maegawa, Yoshifumi; Goto, Yasutomo; Hara, Kenji; Inagaki, Shinji

    2016-07-04

    Heterogenization of metal-complex catalysts for water oxidation without loss of their catalytic activity is important for the development of devices simulating photosynthesis. In this study, efficient heterogeneous iridium complexes for water oxidation were prepared using bipyridine-bridged periodic mesoporous organosilica (BPy-PMO) as a solid chelating ligand. The BPy-PMO-based iridium catalysts (Ir-BPy-PMO) were prepared by postsynthetic metalation of BPy-PMO and characterized through physicochemical analyses. The Ir-BPy-PMOs showed high catalytic activity for water oxidation. The turnover frequency (TOF) values for Ir-BPy-PMOs were one order of magnitude higher than those of conventional heterogeneous iridium catalysts. The reusability and stability of Ir-BPy-PMO were also examined, and detailed characterization was conducted using powder X-ray diffraction, nitrogen adsorption, (13) C DD MAS NMR spectroscopy, TEM, and XAFS methods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Supercritical water oxidation technology development paths for prevention of corrosion and deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, C.; Garcia, K.; Barnes, C.; Beller, J. [EG and G Idaho Inc., Idaho Falls, ID (United States). Idaho National Engineering Lab.

    1994-12-31

    Supercritical Water Oxidation is being developed by the Department of Energy as a promising technology for treatment of mixed waste--that is waste that contains hazardous and radioactive constituents. The aim of this program has been to identify and resolve key technical challenges that have been barriers to commercialization of supercritical water oxidation. Initial testing with benchscale systems indicated that the overriding technical challenge for this technology was prevention of corrosion and deposition inside the reactor. A number of approaches are being pursued to resolve the issue of corrosion and deposition including alternate reactor designs, advanced material development and testing, salt separation processes, and analytical modeling of supercritical water oxidation systems. Ongoing projects in these areas are discussed along with plans for pilot plant testing with promising configurations.

  8. Influence of oxide films on primary water stress corrosion cracking initiation of alloy 600

    Energy Technology Data Exchange (ETDEWEB)

    Panter, J. [Framatome, Centre Technique, BP 181, 71205 Le Creusot cedex (France); Viguier, B. [Centre Inter-Universitaire de Recherche et d' Ingenierie des Materiaux (CIRIMAT), CNRS/INPT/UPS, ENSIACET, 118 Route de Narbonne, 31077 Toulouse cedex 04 (France)]. E-mail: Bernard.Viguier@ensiacet.fr; Cloue, J.-M. [Framatome, Centre Technique, BP 181, 71205 Le Creusot cedex (France); Foucault, M. [Framatome, Centre Technique, BP 181, 71205 Le Creusot cedex (France); Combrade, P. [Framatome, Centre Technique, BP 181, 71205 Le Creusot cedex (France); Andrieu, E. [Centre Inter-Universitaire de Recherche et d' Ingenierie des Materiaux (CIRIMAT), CNRS/INPT/UPS, ENSIACET, 118 Route de Narbonne, 31077 Toulouse cedex 04 (France)

    2006-01-01

    In the present study alloy 600 was tested in simulated pressurised water reactor (PWR) primary water, at 360 deg. C, under an hydrogen partial pressure of 30 kPa. These testing conditions correspond to the maximum sensitivity of alloy 600 to crack initiation. The resulting oxidised structures (corrosion scale and underlying metal) were characterised. A chromium rich oxide layer was revealed, the underlying metal being chromium depleted. In addition, analysis of the chemical composition of the metal close to the oxide scale had allowed to detect oxygen under the oxide scale and particularly in a triple grain boundary. Implication of such a finding on the crack initiation of alloy 600 is discussed. Significant diminution of the crack initiation time was observed for sample oxidised before stress corrosion tests. In view of these results, a mechanism for stress corrosion crack initiation of alloy 600 in PWR primary water was proposed.

  9. Influence of oxide films on primary water stress corrosion cracking initiation of alloy 600

    Science.gov (United States)

    Panter, J.; Viguier, B.; Cloué, J.-M.; Foucault, M.; Combrade, P.; Andrieu, E.

    2006-01-01

    In the present study alloy 600 was tested in simulated pressurised water reactor (PWR) primary water, at 360 °C, under an hydrogen partial pressure of 30 kPa. These testing conditions correspond to the maximum sensitivity of alloy 600 to crack initiation. The resulting oxidised structures (corrosion scale and underlying metal) were characterised. A chromium rich oxide layer was revealed, the underlying metal being chromium depleted. In addition, analysis of the chemical composition of the metal close to the oxide scale had allowed to detect oxygen under the oxide scale and particularly in a triple grain boundary. Implication of such a finding on the crack initiation of alloy 600 is discussed. Significant diminution of the crack initiation time was observed for sample oxidised before stress corrosion tests. In view of these results, a mechanism for stress corrosion crack initiation of alloy 600 in PWR primary water was proposed.

  10. Monitoring Interfacial Lipid Oxidation in Oil-in-Water Emulsions Using Spatially Resolved Optical Techniques.

    Science.gov (United States)

    Banerjee, Chiranjib; Westberg, Michael; Breitenbach, Thomas; Bregnhøj, Mikkel; Ogilby, Peter R

    2017-06-06

    The oxidation of lipids is an important phenomenon with ramifications for disciplines that range from food science to cell biology. The development and characterization of tools and techniques to monitor lipid oxidation are thus relevant. Of particular significance in this regard are tools that facilitate the study of oxidations at interfaces in heterogeneous samples (e.g., oil-in-water emulsions, cell membranes). In this article, we establish a proof-of-principle for methods to initiate and then monitor such oxidations with high spatial resolution. The experiments were performed using oil-in-water emulsions of polyunsaturated fatty acids (PUFAs) prepared from cod liver oil. We produced singlet oxygen at a point near the oil-water interface of a given PUFA droplet in a spatially localized two-photon photosensitized process. We then followed the oxidation reactions initiated by this process with the fluorescence-based imaging technique of structured illumination microscopy (SIM). We conclude that the approach reported herein has attributes well-suited to the study of lipid oxidation in heterogeneous samples.

  11. Optical modeling of nickel-base alloys oxidized in pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2012-10-01

    The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratification model was determined using focused ion beam cross-section of thin foils examined by transmission electron microscopy. Dielectric constants of the inner oxide layer depleted in chromium were assimilated to those of the nickel thin film. The optical constants of both the spinels and extern layer were determined. - Highlights: Black-Right-Pointing-Pointer Spectroscopic ellipsometry of Ni-base alloy oxidation in pressurized water reactor Black-Right-Pointing-Pointer Measurements of the dielectric constants of the alloys Black-Right-Pointing-Pointer Optical simulation of the mixed oxidation process using a three stack model Black-Right-Pointing-Pointer Scattered crystallites cationic outer layer; linear Ni-gradient bottom layer Black-Right-Pointing-Pointer Determination of the refractive index of the spinel and the Cr{sub 2}O{sub 3} layers.

  12. Selective oxidation of organic compounds in waste water by ozone-based oxidation processes

    NARCIS (Netherlands)

    Boncz, M.A.

    2002-01-01

    For many different types of waste water, treatment systems have been implemented in the past decades. Waste water treatment is usually performed by biological processes, either aerobic or anaerobic, complemented with physical / chemical post treatment techniques.

  13. Transparent semiconducting amorphous cadmium-gallium-tin oxide films by magnetron sputtering with water vapor

    Science.gov (United States)

    Yanagi, Hiroshi; Koyamaishi, Yusuke; Sato, Chiyuki; Kimura, Yota

    2017-06-01

    Amorphous oxide semiconductors (including transparent ones) are attractive materials for next-generation optoelectronic applications. One of the difficulties with amorphous oxide semiconductors is the lack of high mobility (>10 cm2 V-1 s-1) at low carrier density (radio-frequency magnetron sputtering with a water-vapor pressure ≥0.25 Pa. In these amorphous films, the threshold carrier density for obtaining high mobility (˜10 cm2 V-1 s-1) is possibly four orders of magnitude lower than that in conventional amorphous oxide semiconductors such as amorphous In-Ga-Zn-O.

  14. An Alternative Reaction Pathway for Iridium Catalyzed Water Oxidation Driven by CAN

    KAUST Repository

    Bucci, Alberto

    2016-06-10

    The generation of solar fuels by means of a photosynthetic apparatus strongly relies on the development of an efficient water oxidation catalyst (WOC). Cerium ammonium nitrate (CAN) is the most commonly used sacrificial oxidant to explore the potentiality of WOCs. It is usually assumed that CAN has the unique role to oxidatively energize WOCs, making them capable to offer a low energy reaction pathway to transform H2O to O2. Herein we show that CAN might have a much more relevant and direct role in WO, mainly related to the capture and liberation of O–O containing molecular moieties.

  15. Water and the oxidation state of subduction zone magmas.

    Science.gov (United States)

    Kelley, Katherine A; Cottrell, Elizabeth

    2009-07-31

    Mantle oxygen fugacity exerts a primary control on mass exchange between Earth's surface and interior at subduction zones, but the major factors controlling mantle oxygen fugacity (such as volatiles and phase assemblages) and how tectonic cycles drive its secular evolution are still debated. We present integrated measurements of redox-sensitive ratios of oxidized iron to total iron (Fe3+/SigmaFe), determined with Fe K-edge micro-x-ray absorption near-edge structure spectroscopy, and pre-eruptive magmatic H2O contents of a global sampling of primitive undegassed basaltic glasses and melt inclusions covering a range of plate tectonic settings. Magmatic Fe3+/SigmaFe ratios increase toward subduction zones (at ridges, 0.13 to 0.17; at back arcs, 0.15 to 0.19; and at arcs, 0.18 to 0.32) and correlate linearly with H2O content and element tracers of slab-derived fluids. These observations indicate a direct link between mass transfer from the subducted plate and oxidation of the mantle wedge.

  16. Possibilities of practical usage of dispersed aluminim oxidation by liquid water

    Science.gov (United States)

    Larichev, M. N.; Laricheva, O. O.; Shaitura, N. S.; Shkolnikov, E. I.

    2012-12-01

    The goal of this work is to show the possibility of practical usage of the environmentally pure oxidation process of preliminarily dispersed aluminum (aluminum powders of the ASD or PAD grade according to TU (Technical Specifications) 48-5-226-87, which are serially produced in industry) with liquid water in order to obtain gaseous hydrogen in volumes sufficient to provide the operation of energizers based on airhydrogen fuel cells (AHFC) for portable and stationary devices (up to 3 kW). It is shown that the synthesis of aluminum oxides-hydroxides with the specified phase and chemical compositions as well as the particle shape and size can be provided simultaneously with producing commercial hydrogen. The practical usage of hydrogen, which is formed in the oxidation reaction of metallic aluminum with liquid water at pressures close to atmospheric (particularly, to service AHFCs), requires reaction intensification to increase the oxidation rate of aluminum. In this work, we considered the aspects of practical implementation of thermal, ultrasonic, and chemical activation as well as their combinations for this purpose. As the chemical activator of oxidation, we used the additives of calcium oxide (<5% of the mass of oxidized aluminum). Application of each activation method affects the phase and chemical compositions as well as the structure of formed aluminum hydroxides, which provides the possibility of their reproducible production. Thus, simultaneously with the production of commercial hydrogen, solid oxidation products satisfying the needs of industry in aluminum oxides and having the specified composition, purity, and particle shape and size can be synthesized. The acquired experimental results and elements of the design of specially developed industrial apparatuses, which were used when performing this work, can be applied when designing the model of the hydrogen generator—the prototype of the hydrogen generator for portable and stationary devices or devices

  17. Lipid oxidation in water-in-olive oil emulsions initiated by a lipophilic radical source.

    Science.gov (United States)

    Mosca, Monica; Ceglie, Andrea; Ambrosone, Luigi

    2010-03-18

    The lipophilic 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) was used to study thoroughly the oxidation reaction in a model water-in-olive oil emulsion system. This radical species decomposes thermally generating a constant flux of radicals in the oil phase. The dissociation constant k(d) in olive oil at 40 degrees C for AMVN was calculated as 2.5 x 10(-4) min(-1) and the rate of initiation of the oxidation reaction, R(i) was calculated by using vitamin E as antioxidant. The olive oil oxidation in emulsion was monitored by measuring the hydroperoxide concentration by a sensitive fluorimetric method. The DPPP (diphenyl-1-pyrenylphosphine) was used as a probe because it reacts stoichiometrically with hydroperoxides to yield a fluorescent product, the diphenyl-1-pyrenylphosphine oxide (DPPP-O). Oxidation data together with emulsion droplet size data showed that in the presence of radical initiator and a large interface, the oxidation reaction is accelerated in W/Olive oil emulsion with respect to whole oil. The mediation of the surface area of water droplets is surely involved in this process because the addition of saturated solutions of ascorbic acid (AA) dispersed in the oil brings about the strong reduction of the oxidation rate even in the presence of the highest AMVN quantity.

  18. Crossing the divide between homogeneous and heterogeneous catalysis in water oxidation.

    Science.gov (United States)

    Vannucci, Aaron K; Alibabaei, Leila; Losego, Mark D; Concepcion, Javier J; Kalanyan, Berç; Parsons, Gregory N; Meyer, Thomas J

    2013-12-24

    Enhancing the surface binding stability of chromophores, catalysts, and chromophore-catalyst assemblies attached to metal oxide surfaces is an important element in furthering the development of dye sensitized solar cells, photoelectrosynthesis cells, and interfacial molecular catalysis. Phosphonate-derivatized catalysts and molecular assemblies provide a basis for sustained water oxidation on these surfaces in acidic solution but are unstable toward hydrolysis and loss from surfaces as the pH is increased. Here, we report enhanced surface binding stability of a phosphonate-derivatized water oxidation catalyst over a wide pH range (1-12) by atomic layer deposition of an overlayer of TiO2. Increased stability of surface binding, and the reactivity of the bound catalyst, provides a hybrid approach to heterogeneous catalysis combining the advantages of systematic modifications possible by chemical synthesis with heterogeneous reactivity. For the surface-stabilized catalyst, greatly enhanced rates of water oxidation are observed upon addition of buffer bases -H2PO(-)(4)/HPO(2-)(4), B(OH)3/B(OH)2 O-, HPO(2-)4 /PO(3-)(4) - and with a pathway identified in which O-atom transfer to OH(-) occurs with a rate constant increase of 10(6) compared to water oxidation in acid.

  19. Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

    Science.gov (United States)

    Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

    2018-01-01

    Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

  20. Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water

    Directory of Open Access Journals (Sweden)

    Ruifeng Zhang

    2017-07-01

    Full Text Available An iron-manganese co-oxide filter film (MeOx has been proven to be a good catalyst for the chemical catalytic oxidation of ammonium in groundwater. Compared with groundwater, surface water is generally used more widely and has characteristics that make ammonium removal more difficult. In this study, MeOx was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeOx was greater than 90%, even though the water quality changed dramatically and the water temperature was reduced to about 6–8 °C. Then, through inactivating microorganisms, it showed that the removal capability of MeOx included both biological (accounted for about 41.05% and chemical catalytic oxidation and chemical catalytic oxidation (accounted for about 58.95%. The investigation of the characterizations suggested that MeOx was formed by abiotic ways and the main elements on the surface of MeOx were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeOx as both ammonia molecules and ammonium ions and the active species of O2 were possibly •O and O2−.

  1. Catalysis of the electrochemical water oxidation to oxygen

    NARCIS (Netherlands)

    Díaz Morales, Oscar Alfonso

    2015-01-01

    This thesis discusses the parameters affecting the catalysis for the electrochemical conversion of water into oxygen. The slow kinetics for the oxygen evolution reaction (OER) is one of the major bottlenecks in the solar energy-to-fuels conversion process, which reduces the efficiency for the

  2. Promotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells

    Science.gov (United States)

    Yang, Lei; Choi, YongMan; Qin, Wentao; Chen, Haiyan; Blinn, Kevin; Liu, Mingfei; Liu, Ping; Bai, Jianming; Tyson, Trevor A.; Liu, Meilin

    2011-01-01

    The existing Ni-yttria-stabilized zirconia anodes in solid oxide fuel cells (SOFCs) perform poorly in carbon-containing fuels because of coking and deactivation at desired operating temperatures. Here we report a new anode with nanostructured barium oxide/nickel (BaO/Ni) interfaces for low-cost SOFCs, demonstrating high power density and stability in C3H8, CO and gasified carbon fuels at 750°C. Synchrotron-based X-ray analyses and microscopy reveal that nanosized BaO islands grow on the Ni surface, creating numerous nanostructured BaO/Ni interfaces that readily adsorb water and facilitate water-mediated carbon removal reactions. Density functional theory calculations predict that the dissociated OH from H2O on BaO reacts with C on Ni near the BaO/Ni interface to produce CO and H species, which are then electrochemically oxidized at the triple-phase boundaries of the anode. This anode offers potential for ushering in a new generation of SOFCs for efficient, low-emission conversion of readily available fuels to electricity. PMID:21694705

  3. Promotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells.

    Science.gov (United States)

    Yang, Lei; Choi, YongMan; Qin, Wentao; Chen, Haiyan; Blinn, Kevin; Liu, Mingfei; Liu, Ping; Bai, Jianming; Tyson, Trevor A; Liu, Meilin

    2011-06-21

    The existing Ni-yttria-stabilized zirconia anodes in solid oxide fuel cells (SOFCs) perform poorly in carbon-containing fuels because of coking and deactivation at desired operating temperatures. Here we report a new anode with nanostructured barium oxide/nickel (BaO/Ni) interfaces for low-cost SOFCs, demonstrating high power density and stability in C(3)H(8), CO and gasified carbon fuels at 750°C. Synchrotron-based X-ray analyses and microscopy reveal that nanosized BaO islands grow on the Ni surface, creating numerous nanostructured BaO/Ni interfaces that readily adsorb water and facilitate water-mediated carbon removal reactions. Density functional theory calculations predict that the dissociated OH from H(2)O on BaO reacts with C on Ni near the BaO/Ni interface to produce CO and H species, which are then electrochemically oxidized at the triple-phase boundaries of the anode. This anode offers potential for ushering in a new generation of SOFCs for efficient, low-emission conversion of readily available fuels to electricity.

  4. Manganese compounds as catalysts for water oxidation and as CO releasing molecules

    OpenAIRE

    Berends, Hans-Martin

    2011-01-01

    This PhD thesis deals with several aspects of manganese chemistry and is divided into three parts. The first two concern the synthesis and characterization of manganese-based water oxidation catalysts. The four-electron oxidation of water to dioxygen is a key process of oxygenic photosynthesis in which solar energy is captured and stored in the form of carbohydrates. In nature, this reaction is catalyzed by a µ-oxido-Mn4Ca cluster, the oxygen evolving complex (OEC). Mimicking this reacti...

  5. Water as origin of hysteresis in zinc tin oxide thin-film transistors.

    Science.gov (United States)

    Fakhri, M; Johann, H; Görrn, P; Riedl, T

    2012-09-26

    The hysteresis behavior of transparent zinc tin oxide (ZTO) thin film transistors (TFTs) is identified to be a result of short-term bias stress induced by the measurement. The related density of shallow defect states can be adjusted by the amount of water in the ambient. Time-resolved studies of the TFTs under varied ambient demonstrate that hysteresis can be immediately switched on and off by the adsorption and desorption of water, respectively. These findings are expected to be of general importance also for other oxide-based TFTs.

  6. Thermal oxidation synthesis of crystalline iron-oxide nanowires on low-cost steel substrates for solar water splitting

    Science.gov (United States)

    Dlugosch, T.; Chnani, A.; Muralidhar, P.; Schirmer, A.; Biskupek, J.; Strehle, S.

    2017-08-01

    Iron-oxide and in particular its crystallographic phase hematite (α-Fe2O3) is a promising candidate for non-toxic, earth abundant and low cost photo-anodes in the field of photo-electrochemical water splitting. We report here on the synthesis of α-Fe2O3 nanowires by thermal oxidation of low-cost steel substrates. Nanowires grown in this manner exhibit often a blade-like shape but can also possess a wire-like geometry partly decorated at their tip with an iron-rich ellipsoidal head consisting also of crystalline iron-oxide. We show furthermore that these ellipsoidal heads represent suitable growth sites leading in some cases to an additional growth of so-called antenna nanowires. Besides nanowires also nanoflakes were frequently observed at the surface. We discuss the influence of the oxidation temperature and other synthesis parameters as well as dispute the current growth models. Finally, we show that our α-Fe2O3 nanostructures on steel are also photo-electrochemically active supporting in principle their use as photo-anode material.

  7. In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

    Directory of Open Access Journals (Sweden)

    Basseem B. Hallac

    2018-02-01

    Full Text Available The extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt % lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe3O4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible light using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe2O3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe+2.57 for the catalyst with no lanthana and Fe+2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe+2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe+2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. The paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.

  8. Water transport through graphene oxide membranes: the roles of driving forces.

    Science.gov (United States)

    Chong, J Y; Wang, B; Li, K

    2018-02-21

    Graphene oxide (GO) membranes have shown excellent selectivities in nanofiltration and pervaporation. However, the water transport mechanisms in the unique membrane laminar structure are still not well understood, especially in pervaporation which involves selective permeation and evaporation. Herein, water transport in GO membranes was tested under two different modes: pressure-driven permeation and pervaporation. The pure water flux was found to be 1-2 orders of magnitude higher in pervaporation due to the large capillary pressure induced by evaporation. The water flux in pervaporation was suggested to be limited by evaporation at room temperature but surface diffusion at high temperature.

  9. Graphene oxide/ferroferric oxide/polyethylenimine nanocomposites for Congo red adsorption from water.

    Science.gov (United States)

    Wang, Lina; Mao, Changming; Sui, Ning; Liu, Manhong; Yu, William W

    2017-04-01

    Graphene oxide/ferroferric oxide/polyethylenimine (GO/Fe 3 O 4 /PEI) nanocomposites were synthesized by an in situ growth of Fe 3 O 4 nanoparticles on GO sheets, and then modified by PEI. The GO/Fe 3 O 4 /PEI nanocomposites showed extremely high removal efficiency for anionic dye Congo Red (CR) due to the positively charged PEI molecules (methylene blue was also tested but with low adsorption capacity due to its cationic property). The CR removal capacity was 574.7 mg g -1 , higher than most of reported results. The adsorption kinetics could be well described by a pseudo-second-order model. Furthermore, GO/Fe 3 O 4 /PEI nanocomposites could be easily recycled by magnetic separation. The removal efficiency remained above 70% after five cycles.

  10. Electrochemical Water Oxidation by a Catalyst-Modified Metal-Organic Framework Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shaoyang; Pineda-Galvan, Yuliana; Maza, William A.; Epley, Charity C.; Zhu, Jie; Kessinger, Matthew C.; Pushkar, Yulia; Morris, Amanda J. (VP); (Purdue)

    2016-12-15

    Water oxidation, a key component in artificial photosynthesis, requires high overpotentials and exhibits slow reaction kinetics that necessitates the use of stable and efficient heterogeneous water-oxidation catalysts (WOCs). Here, we report the synthesis of UiO-67 metal–organic framework (MOF) thin films doped with [Ru(tpy)(dcbpy)OH2]2+ (tpy=2,2':6',2''-terpyridine, dcbpy=5,5'-dicarboxy-2,2'-bipyridine) on conducting surfaces and their propensity for electrochemical water oxidation. The electrocatalyst oxidized water with a turnover frequency (TOF) of (0.2±0.1) s-1 at 1.71 V versus the normal hydrogen electrode (NHE) in buffered solution (pH~7) and exhibited structural and electrochemical stability. The electroactive sites were distributed throughout the MOF thin film on the basis of scan-ratedependent voltammetry studies. This work demonstrates a promising way to immobilize large concentrations of electroactive WOCs into a highly robust MOF scaffold and paves the way for future photoelectrochemical water-splitting systems.

  11. Water Oxidation Catalysis by Co(II) Impurities in Co(III) 4 O 4 Cubanes

    Energy Technology Data Exchange (ETDEWEB)

    Ullman, Andrew M.; Liu, Yi; Huynh, Michael; Bediako, D. Kwabena; Wang, Hongsen; Anderson, Bryce L.; Powers, David C.; Breen, John J.; Abruña, Héctor D.; Nocera, Daniel G.

    2014-12-17

    The observed water oxidation activity of the compound class Co4O4(OAc)4(Py–X)4 emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co4O4 molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.

  12. Light induced oxidative water splitting in photosynthesis: energetics, kinetics and mechanism.

    Science.gov (United States)

    Renger, Gernot

    2011-01-01

    The essential steps of photosynthetic water splitting take place in Photosystem II (PSII) and comprise three different reaction sequences: (i) light induced formation of the radical pair P680(+)Q(A)(-), (ii) P680(+) driven oxidative water splitting into O(2) and four protons, and (iii) two step plastoquinone reduction to plastoquinol by Q(A)(-). This mini-review briefly summarizes our state of knowledge on energetics, kinetics and mechanism of oxidative water splitting. Essential features of the two types of reactions involved are described: (a) P680(+) reduction by the redox active tyrosine Y(z) and (b) sequence of oxidation steps induced by Y(z)(ox) in the water-oxidizing complex (WOC). The rate of the former reaction is limited by the non-adiabatic electron transfer (NET) step and the multi-phase kinetics shown to originate from a sequence of relaxation processes. In marked contrast, the rate of the stepwise oxidation by Y(z)(ox) of the WOC up to the redox level S(3) is not limited by NET but by trigger reactions which probably comprise proton shifts and/or conformational changes. The overall rate of the final reaction sequence leading to formation and release of O(2) is assumed to be limited by the electron transfer step from the S(3) state of WOC to Y(z)(ox) due to involvement of an endergonic redox equilibrium. Currently discussed controversial ideas on possible pathways are briefly outlined. Several crucial points of the mechanism of oxidative water splitting, like O-O bond formation, role of local proton shift(s), details of hydrogen bonding, are still not clarified and remain a challenging topic of future research. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Permanent water swelling effect in low temperature thermally reduced graphene oxide

    Science.gov (United States)

    Papamatthaiou, S.; Argyropoulos, D.-P.; Masurkar, A.; Cavallari, M. R.; Farmakis, F.; Kymissis, I.; Georgoulas, N.

    2017-06-01

    We demonstrate permanent water trapping in reduced graphene oxide after high relative humidity exposure. For this purpose, we grew graphene oxide films via spin-coating on glass substrates followed by thermal reduction. The electrical resistance of the planar device was then measured. We observed that resistance is significantly increased after water vapor exposure and remains stable even after 250 days in ambient conditions. Various techniques were applied to desorb the water and decrease (recover) the material's resistance, but it was achieved only with low temperature thermal annealing (180 °C) under forming gas (H2/N2 mixture). The permanent effect of water absorption was also detected by x-ray photoelectron spectroscopy.

  14. Post-treatment of reclaimed waste water based on an electrochemical advanced oxidation process

    Science.gov (United States)

    Verostko, Charles E.; Murphy, Oliver J.; Hitchens, G. D.; Salinas, Carlos E.; Rogers, Tom D.

    1992-01-01

    The purification of reclaimed water is essential to water reclamation technology life-support systems in lunar/Mars habitats. An electrochemical UV reactor is being developed which generates oxidants, operates at low temperatures, and requires no chemical expendables. The reactor is the basis for an advanced oxidation process in which electrochemically generated ozone and hydrogen peroxide are used in combination with ultraviolet light irradiation to produce hydroxyl radicals. Results from this process are presented which demonstrate concept feasibility for removal of organic impurities and disinfection of water for potable and hygiene reuse. Power, size requirements, Faradaic efficiency, and process reaction kinetics are discussed. At the completion of this development effort the reactor system will be installed in JSC's regenerative water recovery test facility for evaluation to compare this technique with other candidate processes.

  15. Application of Metal Oxide Heterostructures in Arsenic Removal from Contaminated Water

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2014-01-01

    Full Text Available It has become one of the major environmental problems for people worldwide to be exposed to high arsenic concentrations through contaminated drinking water, and even the long-term intake of small doses of arsenic has a carcinogenic effect. As an efficient and economic approach for the purification of arsenic-containing water, the adsorbents in adsorption processes have been widely studied. Among a variety of adsorbents reported, the metal oxide heterostructures with high surface area and specific affinity for arsenic adsorption from aqueous systems have demonstrated a promising performance in practical applications. This review paper aims to summarize briefly the metal oxide heterostructures in arsenic removal from contaminated water, so as to provide efficient, economic, and robust solutions for water purification.

  16. Engineered nanomaterials for water treatment and remediation: Costs, benefits, and applicability

    OpenAIRE

    Adeleye, AS; Conway, JR; Garner, K.; Y. Huang; Su, Y.; Keller, AA

    2016-01-01

    © 2015 Elsevier B.V. The application of nanotechnology in drinking water treatment and pollution cleanup is promising, as demonstrated by a number of field-based (pilot and full scale) and bench scale studies. A number of reviews exist for these nanotechnology-based applications; but to better illustrate its importance and guide its development, a direct comparison between traditional treatment technologies and emerging approaches using nanotechnology is needed. In this review, the performanc...

  17. Cost and Performance Report Low Impact Technologies to Reduce Pollution from Storm Water Runoff SI-200405

    Science.gov (United States)

    2008-09-01

    Active Substance (MBAS) SM5540C EPA377.1 Nitrogen (Total) SM4500N Ammonia EPA350.2 Total Kjeldahl Nitrogen (TKN) EPA351.3 Nitrite...Prevention Ashore Program), NAVFAC ESC has conducted bench scale tests on 24 different adsorbent media to determine the combination that is the most...water passes through the media. Knowledge of hydraulic conductivity is needed to determine the required availability of hydraulic head for a known

  18. Prevention of enzymatic browning of Chinese yam (Dioscorea spp.) using electrolyzed oxidizing water.

    Science.gov (United States)

    Jia, Guo-Liang; Shi, Jing-Ying; Song, Zhan-Hua; Li, Fa-De

    2015-04-01

    In this study, the effects of electrolyzed oxidizing water (EOW) on the prevention of enzymatic browning of fresh-cut "Jiu Jinhuang" Chinese yam were investigated. The yams were immersed in the inhibitors for 25 min at 20 °C. Compared with the tap water (TW) treatment, the chromatic attributes were significantly different after 72 h of storage (P browning inhibitor. © 2015 Institute of Food Technologists®

  19. Water Radiolysis: Influence of Oxide Surfaces on H2 Production under Ionizing Radiation

    Directory of Open Access Journals (Sweden)

    Sophie Le Caër

    2011-02-01

    Full Text Available The radiolysis of water due to ionizing radiation results in the production of electrons, H· atoms, ·OH radicals, H3O+ ions and molecules (dihydrogen H2 and hydrogen peroxide H2O2. A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H2 production. This H2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented.

  20. Stripped sour water treatment by advanced oxidation processes

    OpenAIRE

    Guimarães, José R.; Gasparini, Mirthys C.; Maniero,Milena G.; Mendes, Carlos G. N.

    2012-01-01

    This study assessed the application of photolysis (UV), peroxidation (H2O2), peroxidation combined with ultraviolet light (UV/H2O2), Fenton’s reagent (H2O2/Fe(II)) and photo-Fenton (H2O2/Fe(II)/UV) processes in the treatment of stripped sour water from the Petrobras Replan Oil Refinery in Paulínia City, São Paulo State, Brazil. To evaluate the efficiency of the process, the concentration of dissolved organic carbon (DOC) was monitored throughout the reaction period. Among the evaluated proces...

  1. Kinetics of Chronic Oxidation of NBG-17 Nuclear Graphite by Water Vapor

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burchell, Timothy D [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mee, Robert [Univ. of Tennessee, Knoxville, TN (United States)

    2015-05-01

    This report presents the results of kinetic measurements during accelerated oxidation tests of NBG-17 nuclear graphite by low concentration of water vapor and hydrogen in ultra-high purity helium. The objective is to determine the parameters in the Langmuir-Hinshelwood (L-H) equation describing the oxidation kinetics of nuclear graphite in the helium coolant of high temperature gas-cooled reactors (HTGR). Although the helium coolant chemistry is strictly controlled during normal operating conditions, trace amounts of moisture (predictably < 0.2 ppm) cannot be avoided. Prolonged exposure of graphite components to water vapor at high temperature will cause very slow (chronic) oxidation over the lifetime of graphite components. This behavior must be understood and predicted for the design and safe operation of gas-cooled nuclear reactors. The results reported here show that, in general, oxidation by water of graphite NBG-17 obeys the L-H mechanism, previously documented for other graphite grades. However, the characteristic kinetic parameters that best describe oxidation rates measured for graphite NBG-17 are different than those reported previously for grades H-451 (General Atomics, 1978) and PCEA (ORNL, 2013). In some specific conditions, certain deviations from the generally accepted L-H model were observed for graphite NBG-17. This graphite is manufactured in Germany by SGL Carbon Group and is a possible candidate for the fuel elements and reflector blocks of HTGR.

  2. Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides

    Science.gov (United States)

    2015-01-01

    Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic–electronic conducting perovskite-type materials La0.6Sr0.4FeO3−δ (LSF) and SrTi0.7Fe0.3O3−δ (STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2 was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities. PMID:26045733

  3. Water oxidation by a cytochrome p450: mechanism and function of the reaction.

    Science.gov (United States)

    Prasad, Brinda; Mah, Derrick J; Lewis, Andrew R; Plettner, Erika

    2013-01-01

    P450(cam) (CYP101A1) is a bacterial monooxygenase that is known to catalyze the oxidation of camphor, the first committed step in camphor degradation, with simultaneous reduction of oxygen (O2). We report that P450(cam) catalysis is controlled by oxygen levels: at high O2 concentration, P450(cam) catalyzes the known oxidation reaction, whereas at low O2 concentration the enzyme catalyzes the reduction of camphor to borneol. We confirmed, using (17)O and (2)H NMR, that the hydrogen atom added to camphor comes from water, which is oxidized to hydrogen peroxide (H2O2). This is the first time a cytochrome P450 has been observed to catalyze oxidation of water to H2O2, a difficult reaction to catalyze due to its high barrier. The reduction of camphor and simultaneous oxidation of water are likely catalyzed by the iron-oxo intermediate of P450(cam) , and we present a plausible mechanism that accounts for the 1:1 borneol:H2O2 stoichiometry we observed. This reaction has an adaptive value to bacteria that express this camphor catabolism pathway, which requires O2, for two reasons: 1) the borneol and H2O2 mixture generated is toxic to other bacteria and 2) borneol down-regulates the expression of P450(cam) and its electron transfer partners. Since the reaction described here only occurs under low O2 conditions, the down-regulation only occurs when O2 is scarce.

  4. Removal of fluoride from water using iron oxide-hydroxide nanoparticles.

    Science.gov (United States)

    Raul, Prasanta Kumar; Devi, Rashmi Rekha; Umlong, Iohborlang M; Banerjee, Saumen; Singh, Lokendra; Purkait, Mihir

    2012-05-01

    A novel and facile method for the synthesis of uniform stoichiometric powder form of non-magnetic iron oxide-hydroxide nanoparticles with spherical morphology and its application for defluoridation of drinking water is reported. X-ray powder diffraction analysis (XRD), BET surface area, FTIR, field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) images were used to characterize nanoscale iron oxide-hydroxide. Transmission electron microscopy (TEM) image revealed the formation of iron oxide-hydroxide nanoparticles with spherical morphology. The iron oxide-hydroxide nanoparticles showed an excellent ability to remove fluoride (F-) from contaminated water over a wide range of pH. The influences of temperature, stirring speed, pH, adsorbent dose and contact time were studied. The equilibrium data were tested with various isotherm models and finally, a calculation procedure was reported for the calculation of adsorbent requirement. The fluoride adsorbed nanoparticles was regenerated upto 70% using sodium hydroxide or hydrochloric acid solution. The iron oxide-hydroxide nanoparticles can be used as an effective and replicable adsorbent media for defluoridation of water in presence of competing anions like chloride, iodate, iodide and sulphate.

  5. Influence of Adsorbed Water on the Oxygen Evolution Reaction on Oxides

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Vojvodic, Aleksandra

    2015-01-01

    We study the interface between adsorbed water and stoichiometric, defect-free (110) rutile oxide surfaces of TiO2, RuO2, and IrO2 in order to understand how water influences the stabilities of the intermediates of the oxygen evolution reaction (OER). In our model the water is treated as explicitly...... molecules binding to bridging oxygens. The third chain interacts weakly and predominantly with the H2O molecules of the second layer, resembling bulk water. We find that the stability of the water layer close to the oxide surface is almost the same as the one found on flat metal surfaces, such as the Pt(111...... adsorbed H2O molecules, which are found to form two-dimensional water chains (layers) on all investigated oxide surfaces. The first chain formed by the most strongly bound H2O molecules is adsorbed on the 5-fold coordinated surface metal atoms. The second chain is composed of less strongly bound H2O...

  6. Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins

    Directory of Open Access Journals (Sweden)

    N. D. D. Carareto

    2010-03-01

    Full Text Available The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models.

  7. Plutonium Oxide Containment and the Potential for Water-Borne Transport as a Consequence of ARIES Oxide Processing Operations

    Energy Technology Data Exchange (ETDEWEB)

    Wayne, David Matthew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rowland, Joel C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-01

    The question of oxide containment during processing and storage has become a primary concern when considering the continued operability of the Plutonium Facility (PF-4) at Los Alamos National Laboratory (LANL). An Evaluation of the Safety of the Situation (ESS), “Potential for Criticality in a Glovebox Due to a Fire” (TA55-ESS-14-002-R2, since revised to R3) first issued in May, 2014 summarizes these concerns: “The safety issue of fire water potentially entering a glovebox is: the potential for the water to accumulate in the bottom of a glovebox and result in an inadvertent criticality due to the presence of fissionable materials in the glovebox locations and the increased reflection and moderation of neutrons from the fire water accumulation.” As a result, the existing documented safety analysis (DSA) was judged inadequate and, while it explicitly considered the potential for criticality resulting from water intrusion into gloveboxes, criticality safety evaluation documents (CSEDs) for the affected locations did not evaluate the potential for fire water intrusion into a glovebox.

  8. Alpha Radiolysis of Sorbed Water on Uranium Oxides and Uranium Oxyfluorides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2003-09-10

    The radiolysis of sorbed water and other impurities contained in actinide oxides has been the focus of a number of studies related to the establishment of criteria for the safe storage and transport of these materials. Gamma radiolysis studies have previously been performed on uranium oxides and oxyfluorides (UO{sub 3}, U{sub 3}O{sub 8}, and UO{sub 2}F{sub 2}) to evaluate the long-term storage characteristics of {sup 233}U. This report describes a similar study for alpha radiolysis. Uranium oxides and oxyfluorides (with {sup 238}U as the surrogate for {sup 233}U) were subjected to relatively high alpha radiation doses (235 to 634 MGy) by doping with {sup 244}Cm. The typical irradiation time for these samples was about 1.5 years, which would be equivalent to more than 50 years irradiation by a {sup 233}U sample. Both dry and wet (up to 10 wt % water) samples were examined in an effort to identify the gas pressure and composition changes that occurred as a result of radiolysis. This study shows that several competing reactions occur during radiolysis, with the net effect that only very low pressures of hydrogen, nitrogen, and carbon dioxide are generated from the water, nitrate, and carbon impurities, respectively, associated with the oxides. In the absence of nitrate impurities, no pressures greater than 1000 torr are generated. Usually, however, the oxygen in the air atmosphere over the oxides is consumed with the corresponding oxidation of the uranium oxide. In the presence of up to 10 wt % water, the oxides first show a small pressure rise followed by a net decrease due to the oxygen consumption and the attainment of a steady-state pressure where the rate of generation of gaseous components is balanced by their recombination and/or consumption in the oxide phase. These results clearly demonstrate that alpha radiolysis of either wet or dry {sup 233}U oxides will not produce deleterious pressures or gaseous components that could compromise the long-term storage of

  9. Oxidative dissolution of unirradiated Mimas MOX fuel (U/Pu oxides) in carbonated water under oxic and anoxic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Odorowski, Mélina [CEA/DEN/DTCD/SECM/LMPA, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); MINES ParisTech, PSL Research University, Centre de Géosciences, 35 rue St Honoré, 77305 Fontainebleau (France); Jégou, Christophe, E-mail: christophe.jegou@cea.fr [CEA/DEN/DTCD/SECM/LMPA, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); De Windt, Laurent [MINES ParisTech, PSL Research University, Centre de Géosciences, 35 rue St Honoré, 77305 Fontainebleau (France); Broudic, Véronique; Peuget, Sylvain; Magnin, Magali; Tribet, Magaly [CEA/DEN/DTCD/SECM/LMPA, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Martin, Christelle [Agence nationale pour la gestion des déchets radioactifs (Andra), DRD/CM, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry Cedex (France)

    2016-01-15

    Few studies exist concerning the alteration of Mimas Mixed-OXide (MOX) fuel, a mixed plutonium and uranium oxide, and data is needed to better understand its behavior under leaching, especially for radioactive waste disposal. In this study, two leaching experiments were conducted on unirradiated MOX fuel with a strong alpha activity (1.3 × 10{sup 9} Bq.g{sub MOX}{sup −1} reproducing the alpha activity of spent MOX fuel with a burnup of 47 GWd·t{sub HM}{sup −1} after 60 years of decay), one under air (oxic conditions) for 5 months and the other under argon (anoxic conditions with [O{sub 2}] < 1 ppm) for one year in carbonated water (10{sup −2} mol L{sup −1}). For each experiment, solution samples were taken over time and Eh and pH were monitored. The uranium in solution was assayed using a kinetic phosphorescence analyzer (KPA), plutonium and americium were analyzed by a radiochemical route, and H{sub 2}O{sub 2} generated by the water radiolysis was quantified by chemiluminescence. Surface characterizations were performed before and after leaching using Scanning Electron Microscopy (SEM), Electron Probe Microanalyzer (EPMA) and Raman spectroscopy. Solubility diagrams were calculated to support data discussion. The uranium releases from MOX pellets under both oxic and anoxic conditions were similar, demonstrating the predominant effect of alpha radiolysis on the oxidative dissolution of the pellets. The uranium released was found to be mostly in solution as carbonate species according to modeling, whereas the Am and Pu released were significantly sorbed or precipitated onto the TiO{sub 2} reactor. An intermediate fraction of Am (12%) was also present as colloids. SEM and EPMA results indicated a preferential dissolution of the UO{sub 2} matrix compared to the Pu-enriched agglomerates, and Raman spectroscopy showed the Pu-enriched agglomerates were slightly oxidized during leaching. Unlike Pu-enriched zones, the UO{sub 2} grains were much more

  10. Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

    Science.gov (United States)

    Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

    2013-08-19

    Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

  11. Effect of Support in Heterogeneous Ruthenium Catalysts Used for the Selective Aerobic Oxidation of HMF in Water

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Riisager, Anders

    2011-01-01

    Heterogeneous ruthenium-based catalysts were applied in the selective, aerobic oxidation of 5-hydroxymethylfurfural, a versatile biomass-derived chemical, to form 2,5-furandicarboxylic acid. The oxidation reactions were performed in water with dioxygen as the oxidant at different pressures without...

  12. Computationally Probing the Performance of Hybrid, Heterogeneous, and Homogeneous Iridium-Based Catalysts for Water Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    García-Melchor, Max [SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford CA (United States); Vilella, Laia [Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST),Tarragona (Spain); Departament de Quimica, Universitat Autonoma de Barcelona, Barcelona (Spain); López, Núria [Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Tarragona (Spain); Vojvodic, Aleksandra [SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park CA (United States)

    2016-04-29

    An attractive strategy to improve the performance of water oxidation catalysts would be to anchor a homogeneous molecular catalyst on a heterogeneous solid surface to create a hybrid catalyst. The idea of this combined system is to take advantage of the individual properties of each of the two catalyst components. We use Density Functional Theory to determine the stability and activity of a model hybrid water oxidation catalyst consisting of a dimeric Ir complex attached on the IrO2(110) surface through two oxygen atoms. We find that homogeneous catalysts can be bound to its matrix oxide without losing significant activity. Hence, designing hybrid systems that benefit from both the high tunability of activity of homogeneous catalysts and the stability of heterogeneous systems seems feasible.

  13. Zinc adsorption effects on arsenite oxidation kinetics at the birnessite-water interface

    Science.gov (United States)

    Power, L.E.; Arai, Y.; Sparks, D.L.

    2005-01-01

    Arsenite is more toxic and mobile than As(V) in soil and sediment environments, and thus it is advantageous to explore factors that enhance oxidation of As(III) to As(V). Previous studies showed that manganese oxides, such as birnessite (??-MnO2), directly oxidized As(III). However, these studies did not explore the role that cation adsorption has on As(III) oxidation. Accordingly, the effects of adsorbed and nonadsorbed Zn on arsenite (As(III)) oxidation kinetics at the birnessite-water interface were investigated using batch adsorption experiments (0.1 g L-1; pH 4.5 and 6.0; I = 0.01 M NaCl). Divalent Zn adsorption on synthetic ??-MnO 2 in the absence of As(III) increased with increasing pH and caused positive shifts in electrophoretic mobility values at pH 4-6, indirectly suggesting inner-sphere Zn adsorption mechanisms. Arsenite was readily oxidized on birnessite in the absence of Zn. The initial As(III) oxidation rate constant decreased with increasing pH from 4.5 to 6.0 and initial As(III) concentrations from 100 to 300 ??M. Similar pH and initial As(III) concentration effects were observed in systems when Zn was present (i.e., presorbed Zn prior to As(III) addition and simultaneously added Zn-As(III) systems), but As(III) oxidation reactions were suppressed compared to the respective control systems. The suppression was more pronounced when Zn was presorbed on the ??-MnO 2 surfaces as opposed to added simultaneously with As(III). This study provides further understanding of As(III) oxidation reactions on manganese oxide surfaces under environmentally applicable conditions where metals compete for reactive sites.

  14. Destabilization of the hydrogen-bond structure of water by the osmolyte trimethylamine N-oxide

    NARCIS (Netherlands)

    Rezus, Y.L.A.; Bakker, H.J.

    2009-01-01

    We use femtosecond mid-infrared pump−probe spectroscopy to investigate the effects of the osmolyte trimethylamine N-oxide (TMAO) on the structural dynamics of water. As a comparison, we also investigate the effects of other amphiphilic molecules: tetramethylurea (TMU), urea, proline, and

  15. Electrochemical oxidation of tetracycline in water and microbiology investigations of products

    Energy Technology Data Exchange (ETDEWEB)

    Baturova, M.; Vedenjapin, A. [N.D. Zelinsky Inst. of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Univ. of Hannover, Inst. of Water Quality and Waste Management, Hannover (Germany); Skundin, A. [A.N. Frumkin Inst. of Electrochemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2003-07-01

    A possibility to use electrochemical treatment for tetracyclinee (TC) removal from waste water and pig farm sewage was studied. It was found that TC can be oxidized at platinum and carbon anodes with formation of harmless products, carbon anode being more effective than platinum one. (orig.)

  16. Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water

    NARCIS (Netherlands)

    van der Grift, B.; Rozemeijer, J. C.|info:eu-repo/dai/nl/304838403; Griffioen, J.; van der Velde, Y.

    2014-01-01

    The retention of phosphorus in surface waters though co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from

  17. How to make an efficient and robust molecular catalyst for water oxidation.

    Science.gov (United States)

    Garrido-Barros, Pablo; Gimbert-Suriñach, Carolina; Matheu, Roc; Sala, Xavier; Llobet, Antoni

    2017-10-16

    Energy has been a central subject for human development from Homo erectus to date. The massive use of fossil fuels during the last 50 years has generated a large CO2 concentration in the atmosphere that has led to the so-called global warming. It is very urgent to come up with C-neutral energy schemes to be able to preserve Planet Earth for future generations to come and still preserve our modern societies' life style. One of the potential solutions is water splitting with sunlight (hν-WS) that is also associated with "artificial photosynthesis", since its working mode consists of light capture followed by water oxidation and proton reduction processes. The hydrogen fuel generated in this way is named as "solar fuel". For this set of reactions, the catalytic oxidation of water to dioxygen is one of the crucial processes that need to be understood and mastered in order to build up potential devices based on hν-WS. This tutorial describes the different important aspects that need to be considered to come up with efficient and oxidatively robust molecular water oxidation catalysts (Mol-WOCs). It is based on our own previous work and completed with essential contributions from other active groups in the field. We mainly aim at describing how the ligands can influence the properties of the Mol-WOCs and showing a few key examples that overall provide a complete view of today's understanding in this field.

  18. Water Oxidation by In Situ Generated [RuII(OH2)(NCNHCO)(pic)2].

    Science.gov (United States)

    Su, Wei; Zhou, Kui; Cai, Fanglin; Chen, Cheng; Mousavi, Bibimaryam; Chaemchuen, Somboon; Verpoort, Francis

    2017-09-05

    A dinuclear ruthenium complex [Ru II (NC NHC O)(pic) 2 ] 2 2+ (2) was firstly prepared and characterized spectroscopically and electrochemically. Instead of the conventional ligand exchange, complex 2 dissociates in situ to afford two single-site Ru aqua complexes, [Ru II (OH 2 )(NC NHC O)(pic) 2 ] + , which mediates water oxidation through proton-coupled electron transfer events. In electrokinetic studies, complex 2 demonstrated a TOF of 150.3 s -1 comparable to those state-of-the-art catalysts at neutral conditions. TONs of 2173 and 217 were attained in chemical and photochemical water oxidation when 2 was used as a catalyst, exhibiting good stability. Notably, a TOF of 1.3 s -1 was achieved at CAN-driven water oxidation, which outperformed most of the reported single-site Ru complexes, indicating that complex 2 is one of most active water oxidation catalysts (WOCs) to date. The unique coordination configuration and outstanding catalytic performance of complex 2 might shed light on the design of novel molecular WOCs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Biological iron(II) oxidation as pre-treatment to limestone neutralisation of acid water

    CSIR Research Space (South Africa)

    Maree, JP

    1998-01-01

    Full Text Available Iron (II) should be oxidised to iron (III) before the neutralisation of acid water with limestone, otherwise the oxidation will occur downstream of the neutralisation plant with the formation of acid (reactions 1 and 2). This study aimed...

  20. Star block-copolymers: Enzyme-inspired catalysts for oxidation of alcohols in water

    KAUST Repository

    Mugemana, Clement

    2014-01-01

    A number of fluorous amphiphilic star block-copolymers containing a tris(benzyltriazolylmethyl)amine motif have been prepared. These polymers assembled into well-defined nanostructures in water, and their mode of assembly could be controlled by changing the composition of the polymer. The polymers were used for enzyme-inspired catalysis of alcohol oxidation. This journal is © the Partner Organisations 2014.

  1. Integrated iron(II) oxidation and limestone neutralisation of acid mine water

    CSIR Research Space (South Africa)

    Maree, JP

    1999-01-01

    Full Text Available Volumetric iron (II) oxidation rates exceeding 100 g/(l.d) were achieved by dosing powdered limestone to a bio-reactor treating artificial acid mine water. Neutralisation and partial sulphate removal were achieved as well. The rate is highly...

  2. Highly selective nitroxyl radical-mediated oxidation of primary alcohol groups in water-soluble glucans

    NARCIS (Netherlands)

    Nooy, A.E.J. de; Besemer, A.C.; Bekkum, H. van

    1995-01-01

    With catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and hypochlorite/bromide as the regenerating oxidant in water, primary alcohol groups in glucans and derivatives thereof were rapidly and completely oxidised. For pyranosides, selectivity was higher than 95% and no side products

  3. Fe(II) oxidation kinetics and Fe hydroxyphosphate precipitation upon aeration of anaerobic (ground)water

    NARCIS (Netherlands)

    van der Grift, B.|info:eu-repo/dai/nl/373433484; Griffioen, J.|info:eu-repo/dai/nl/091129265; Behrends, T.|info:eu-repo/dai/nl/30484358X; Wassen, M.J.|info:eu-repo/dai/nl/07165710X; Schot, P.P.|info:eu-repo/dai/nl/08071563X; Osté, Leonard

    2015-01-01

    Exfiltration of anaerobic Fe-rich groundwater into surface water plays an important role in controlling the transport of phosphate (P) from agricultural areas to the sea. Previous laboratory and field studies showed that Fe(II) oxidation upon aeration leads to effective immobilization of dissolved P

  4. TiO2-Based Advanced Oxidation Nanotechnologies For Water Purification And Reuse

    Science.gov (United States)

    TiO2 photocatalysis, one of the UV-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness of TiO2 to generate ...

  5. Spruce galactoglucomannans inhibit the lipid oxidation in rapeseed oil-in-water emulsions

    Science.gov (United States)

    Oil-in-water emulsions are functional and industrially valuable systems, whose large interfacial area makes them prone to deterioration, due in part to as the oxidation and oligomerization of polyunsaturated fatty acids. Spruce galactoglucomannans (GGM), wood biomacromolecules abundantly available f...

  6. The Oxidative Stress Response in Elite Water Polo Players: Effects of Genetic Background

    Directory of Open Access Journals (Sweden)

    Mercurio Vecchio

    2017-01-01

    Full Text Available Acute exercise is known to induce oxidative stress. Here we assessed the effects of gene polymorphisms SOD2 A16V, CAT −844 G>A, and GPx-1 rs1800668 C>T on oxidative stress markers in 28 elite water polo male players prior to and after a routinely programmed friendly match. The mean plasma concentrations of derivatives of reactive oxygen metabolites (dROMs, as well as lactic dehydrogenase (LDH activity, creatine kinase (CK activity, CK-MB, and myoglobin, were significantly increased after exercise, while blood antioxidant potential (BAP and total free thiols were significantly decreased, compared with those measured before exercise. Advanced oxidation protein products (AOPP were also increased after exercise but not significantly. We observed that water polo players having either AV16 or VV16 SOD genotype exhibited a significant increase of postexercise AOPP, LDH, CK, and myoglobin plasma levels in comparison with wild-type athletes. Water polo players having either CAT −844 GA or GPx1 CT genotype showed a significant increase of postexercise dROMs plasma levels and, respectively, GPx and CAT enzyme activities in comparison with wild-type subjects. These preliminary results suggest that the screening for gene variants of antioxidant enzymes could be useful to assess individual susceptibility to oxidative stress and muscle damage in water polo players.

  7. Oxidation kinetics of model compounds of metabolic waste in supercritical water

    Science.gov (United States)

    Webley, Paul A.; Holgate, Henry R.; Stevenson, David M.; Tester, Jefferson W.

    1990-01-01

    In this NASA-funded study, the oxidation kinetics of methanol and ammonia in supercritical water have been experimentally determined in an isothermal plug flow reactor. Theoretical studies have also been carried out to characterize key reaction pathways. Methanol oxidation rates were found to be proportional to the first power of methanol concentration and independent of oxygen concentration and were highly activated with an activation energy of approximately 98 kcal/mole over the temperature range 480 to 540 C at 246 bar. The oxidation of ammonia was found to be catalytic with an activation energy of 38 kcal/mole over temperatures ranging from 640 to 700 C. An elementary reaction model for methanol oxidation was applied after correction for the effect of high pressure on the rate constants. The conversion of methanol predicted by the model was in good agreement with experimental data.

  8. Auto-inhibition effects in anodic oxidation of phenols for electrochemical waste-water purification

    Directory of Open Access Journals (Sweden)

    B. E. CONWAY

    2001-12-01

    Full Text Available Removal or modification of noxious organic impurities in waste-waters is a major challenge for environmental science. Pollutants such as phenols and their derivatives, as well as PCBs, have attracted special attention. In recent years, the possibilities of effecting direct electrocatalytic oxidations at high-area electrodes such as supported Pt or RuO2 have been investigated. However, in a number of cases, especially with phenolic impurities, application of anodic oxidation fails to lead to continuous Faradaic oxidation currents owing to the electrode surfaces becoming blocked with polymeric oxidation products leading to auto-inhibition (“passivation” of the desired electrode process. Examples of such effects with phenols and related compounds are examined comparatively in the present paper by means of cyclic volatammetry and chronoamperometry.

  9. Homogenization conditions affect the oxidative stability of fish oil enriched milk emulsions: oxidation linked to changes in protein composition at the oil-water interface

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit M.; Baron, Caroline P.; Let, Mette B.

    2007-01-01

    Fish oil was incorporated into milk under different homogenization temperatures (50 and 72 °C) and pressures (5, 15, and 22.5 MPa). Subsequently, the oxidative stability of the milk and changes in the protein composition of the milk fat globule membrane (MFGM) were examined. Results showed...... casein seemed to be present at the oil−water interface with increasing pressure. Overall, the results indicated that a combination of more β-lactoglobulin and less casein at the oil−water interface gave the most stable emulsions with respect to lipid oxidation....... that high pressure and high temperature (72 °C and 22.5 MPa) resulted in less lipid oxidation, whereas low pressure and low temperature (50 °C and 5 MPa) resulted in faster lipid oxidation. Analysis of protein oxidation indicated that especially casein was prone to oxidation. The level of free thiol groups...

  10. Water growth on metals and oxides: binding, dissociation and role of hydroxyl groups.

    Science.gov (United States)

    Salmeron, M; Bluhm, H; Tatarkhanov, M; Ketteler, G; Shimizu, T K; Mugarza, A; Deng, Xingyi; Herranz, T; Yamamoto, S; Nilsson, A

    2009-01-01

    We discuss the role of the presence of dangling H-bonds from water or from surface hydroxyl species on the wetting behavior of surfaces. Using scanning tunneling and atomic force microscopies and photoelectron spectroscopy, we have examined a variety of surfaces, including mica, oxides and pure metals. We find that in all cases, the availability of free, dangling H-bonds at the surface is crucial for the subsequent growth of wetting water films. In the case of mica, electrostatic forces and H-bonding to surface O atoms determine the water orientation in the first layer and also in subsequent layers with a strong influence in its wetting characteristics. In the case of oxides like TiO2, Cu2O, SiO2 and Al2O3, surface hydroxyls form readily on defects upon exposure to water vapor and help nucleate the subsequent growth of molecular water films. On pure metals, such as Pt, Pd and Ru, the structure of the first water layer and whether or not it exhibits dangling H-bonds is again crucial. Dangling H-bonds are provided by molecules with their plane oriented vertically, or by OH groups formed by the partial dissociation of water. By tying the two H atoms of the water molecules into strong H-bonds with pre-adsorbed O on Ru can also quench the wettability of the surface.

  11. Differential contributions of archaeal ammonia oxidizer ecotypes to nitrification in coastal surface waters.

    Science.gov (United States)

    Smith, Jason M; Casciotti, Karen L; Chavez, Francisco P; Francis, Christopher A

    2014-08-01

    The occurrence of nitrification in the oceanic water column has implications extending from local effects on the structure and activity of phytoplankton communities to broader impacts on the speciation of nitrogenous nutrients and production of nitrous oxide. The ammonia-oxidizing archaea, responsible for carrying out the majority of nitrification in the sea, are present in the marine water column as two taxonomically distinct groups. Water column group A (WCA) organisms are detected at all depths, whereas Water column group B (WCB) are present primarily below the photic zone. An open question in marine biogeochemistry is whether the taxonomic definition of WCA and WCB organisms and their observed distributions correspond to distinct ecological and biogeochemical niches. We used the natural gradients in physicochemical and biological properties that upwelling establishes in surface waters to study their roles in nitrification, and how their activity--ascertained from quantification of ecotype-specific ammonia monooxygenase (amoA) genes and transcripts--varies in response to environmental fluctuations. Our results indicate a role for both ecotypes in nitrification in Monterey Bay surface waters. However, their respective contributions vary, due to their different sensitivities to surface water conditions. WCA organisms exhibited a remarkably consistent level of activity and their contribution to nitrification appears to be related to community size. WCB activity was less consistent and primarily constrained to colder, high nutrient and low chlorophyll waters. Overall, the results of our characterization yielded a strong, potentially predictive, relationship between archaeal amoA gene abundance and the rate of nitrification.

  12. Benefits of neutral electrolyzed oxidizing water as a drinking water additive for broiler chickens

    National Research Council Canada - National Science Library

    Bügener, E; Kump, A. Wilms-Schulze; Casteel, M; Klein, G

    2014-01-01

    .... At each farm, 3 rearing periods were included in the study. With EO water as the water additive, the total viable cell count and the number of Escherichia coli in drinking water samples were reduced compared with the respective control group...

  13. Hematite modified tungsten trioxide nanoparticle photoanode for solar water oxidation

    Science.gov (United States)

    Mao, Aiming; Kim, Jung Kyu; Shin, Kahee; Wang, Dong Hwan; Yoo, Pil J.; Han, Gui Young; Park, Jong Hyeok

    2012-07-01

    Hematite (α-Fe2O3) film is electrochemically deposited onto the surface of tungsten trioxide (WO3) nanoparticulate film. The synthesis of the WO3 nanostructure is directed by surfactants for control of its morphology. The resulting composite shows visible light harvesting and is tested as photoanodes in heterojunction photoelectrochemical cells for the possibility of direct water splitting under visible illumination. The composite's structural and optical properties are characterized by FESEM, EDS, XRD, XPS, and UV-vis spectrometry; its photocurrent responses are also investigated under simulated solar illumination. Coupling WO3 with hematite results in over 9 times greater photocurrent density than that shown by pure WO3 in sodium sulfate electrolyte. This simple modification can significantly improve the performance of WO3.

  14. Detection of viruses in drinking water by concentration on magnetic iron oxide.

    Science.gov (United States)

    Rao, V C; Waghmare, S V; Lakhe, S B

    1981-09-01

    Discharge of raw domestic wastes containing human enteric viruses into water courses, consumption of untreated water from canals, streams, and shallow wells in villages, and cross-contamination of water in the distribution system because of intermittent water supply in urban areas continue to cause widespread outbreaks of infectious hepatitis in India. To detect a low number of viruses in 50- to 100-liter samples of water, a method was developed with magnetic iron oxide as the virus adsorbent. Poliovirus-seeded dechlorinated tap water, adjusted to pH 3.0 and 0.0005 M AlCl3, was filtered through a 10-g bed of iron oxide sandwiched between two AP20 prefilter pads held in a 142-mm-diameter, stainless-steel holder. Virus was eluted from iron oxide by recirculating three times a 100-ml volume of 3% beef extract, pH 9.0. The eluate was reconcentrated to 5 ml by adjusting to pH 3, adding 1 g of iron oxide, stirring for 30 min, and eluting the readsorbed virus with 5 ml of beef extract, pH 9.0. Virus recovery varied from 60 to 80%. Using the above method, we took a survey of drinking water at three locations in Nagpur during 1976 and found the presence of virus in 7 of 50 samples. The quantity of virus recovered ranged from 1 to 7 plaque-forming units per 30 to 60 liters. Virus was detected in some samples even with residual chlorine. No coliforms were detected in the virus-positive samples.

  15. Characterization of interfacial reactions and oxide films on 316L stainless steel in various simulated PWR primary water environments

    Science.gov (United States)

    Chen, Junjie; Xiao, Qian; Lu, Zhanpeng; Ru, Xiangkun; Peng, Hao; Xiong, Qi; Li, Hongjuan

    2017-06-01

    The effect of water chemistry on the electrochemical and oxidizing behaviors of 316L SS was investigated in hydrogenated, deaerated and oxygenated PWR primary water at 310 °C. Water chemistry significantly influenced the electrochemical impedance spectroscopy parameters. The highest charge-transfer resistance and oxide-film resistance occurred in oxygenated water. The highest electric double-layer capacitance and constant phase element of the oxide film were in hydrogenated water. The oxide films formed in deaerated and hydrogenated environments were similar in composition but different in morphology. An oxide film with spinel outer particles and a compact and Cr-rich inner layer was formed in both hydrogenated and deaerated water. Larger and more loosely distributed outer oxide particles were formed in deaerated water. In oxygenated water, an oxide film with hematite outer particles and a porous and Ni-rich inner layer was formed. The reaction kinetics parameters obtained by electrochemical impedance spectroscopy measurements and oxidation film properties relating to the steady or quasi-steady state conditions in the time-period of measurements could provide fundamental information for understanding stress corrosion cracking processes and controlling parameters.

  16. Understanding flocculation mechanism of graphene oxide for organic dyes from water: Experimental and molecular dynamics simulation

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2015-11-01

    Full Text Available Flocculation treatment processes play an important role in water and wastewater pretreatment. Here we investigate experimentally and theoretically the possibility of using graphene oxide (GO as a flocculant to remove methylene blue (MB from water. Experimental results show that GO can remove almost all MB from aqueous solutions at its optimal dosages and molecular dynamics simulations indicate that MB cations quickly congregate around GO in water. Furthermore, PIXEL energy contribution analysis reveals that most of the strong interactions between GO and MB are of a van der Waals (London dispersion character. These results offer new insights for shedding light on the molecular mechanism of interaction between GO and organic pollutants.

  17. Remarkable effect of Pt nanoparticles on visible light-induced oxygen generation from water catalysed by perovskite oxides.

    Science.gov (United States)

    Gupta, Uttam; Naidu, B S; Rao, C N R

    2015-01-14

    Oxidation of water is a challenging process with a positive free energy change and it is purposeful to find good catalysts to facilitate the process. While the perovskite oxides, LaCoO3 and LaMnO3, are good electron transfer catalysts in artificial photosynthesis to produce oxygen by the oxidation of water, the electron transfer is further favoured by the presence of platinum nanoparticles, causing a substantial increase in oxygen evolution.

  18. Synthesis and characterization of alginate beads encapsulated zinc oxide nanoparticles for bacteria disinfection in water.

    Science.gov (United States)

    Motshekga, Sarah Constance; Sinha Ray, Suprakas; Maity, Arjun

    2017-11-03

    The use of polymer nanocomposites as novel materials for water remediation has emerged as a promising alternative for disinfection of bacteria contaminated water. Sodium alginate, a natural biopolymer has been investigated in this study by encapsulating antimicrobial zinc oxide nanoparticles supported bentonite. The confirmation of the alginate nanocomposites was done by use of TEM, SEM-EDS and XRD. The antimicrobial activity of the alginate nanocomposites was investigated by batch studies using surface water and synthetic bacteria contaminated water containing Staphylococcus aureus. The effect of nanocomposite amount and initial bacteria concentration has been studied. The inactivation results indicated that the nanocomposite effectively inactivated bacteria in both the synthetic and surface water. With an amount of 0.5 g of the nanocomposites, no bacteria was observed in the water after 70 min of contact time with initial bacteria concentration of 200 cfu/ml for synthetic water and within a min, no bacteria was observed in the water for surface water. It is worth noting that 200 cfu/ml is the bacteria concentration range in which environmental water is likely to contain. Therefore, the results of this study have indicated that the alginate nanocomposites can be deemed as a potential antimicrobial agent for water disinfection. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. EVALUATING ARSENIC AND MANGANESE REMOVAL FROM WATER BY CHLORINE OXIDATION FOLLOWED BY CLARIFICATION

    Directory of Open Access Journals (Sweden)

    V. G. R. Pires

    2015-06-01

    Full Text Available AbstractThis paper investigates the simultaneous removal of arsenic [As(V or As(III] and manganese [Mn(II] from natural waters of low and high turbidity by clarification (with polyaluminum chloride and aluminum sulfate as primary coagulants associated or not with chlorine pre-oxidation. The results showed that the clarification process exhibited low Mn(II removal, that varied from 6% to 18% and from 19% to 27% for natural waters of low and high turbidity, respectively. The use of chlorine as pre-oxidant increased Mn(II removal up to 77% and was associated with the formation of birnessite. Regarding As(V removal by clarification, particularly for high turbidity water, a concentration lower than that established by the National Drinking Water Quality Standards (10 μg.L-1 was achieved in almost all tests. Oxidation preceding the clarification led to AsIII removal efficiencies from 80% to 90% for both coagulants and types of water.

  20. Pebax®1657/Graphene oxide composite membranes for improved water vapor separation

    KAUST Repository

    Akhtar, Faheem Hassan

    2016-11-02

    In this study composite mixed matrix membranes containing hydrophilic microphase-separated block copolymer (Pebax® 1657) and graphene oxide nanosheets were prepared using a dip coating method. Water vapor and N2 gas permeation were measured as a function of different parameters: (i) layer thickness, (ii) content of graphene oxide (GO), and (iii) content of reduced GO. Surprisingly, a concentration of only 2 wt% of GO nanosheets well dispersed in the Pebax layer boosted the selectivity 8 times by decreasing the water vapor permeance by only 12% whereas N2 gas permeance decreased by 70%. Using reduced GO instead, the water vapor permeance declined by up to 16% with no influence on the N2 gas permeance. We correlated the permeation properties of the mixed matrix membranes with different models and found, that both the modified Nielsen model and the Cussler model give good correlation with experimental findings.

  1. A Co(II)-Ru(II) dyad relevant to light-driven water oxidation catalysis.

    Science.gov (United States)

    López, Alejandro Montellano; Natali, Mirco; Pizzolato, Erica; Chiorboli, Claudio; Bonchio, Marcella; Sartorel, Andrea; Scandola, Franco

    2014-06-28

    Artificial photosynthesis aims at efficient water splitting into hydrogen and oxygen, by exploiting solar light. As a priority requirement, this process entails the integration of suitable multi-electron catalysts with light absorbing units, where charge separation is generated in order to drive the catalytic routines. The final goal could be the transposition of such an asset into a photoelectrocatalytic cell, where the two half-reactions, proton reduction to hydrogen and water oxidation to oxygen, take place at two appropriately engineered photoelectrodes. We herein report a covalent approach to anchor a Co(II) water oxidation catalyst to a Ru(II) polypyridine photosensitizer unit; photophysical characterisation and the catalytic activity of such a dyad in a light activated cycle are reported, and implications for the development of regenerative systems are discussed.

  2. Effect of supplementation of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives.

    Science.gov (United States)

    Talikoti, Prashanth; Bobby, Zachariah; Hamide, Abdoul

    2015-01-01

    The objective of the study was to evaluate the effect of water-soluble vitamins on oxidative stress and blood pressure in prehypertensives. Sixty prehypertensives were recruited and randomized into 2 groups of 30 each. One group received water-soluble vitamins and the other placebo for 4 months. Further increase in blood pressure was not observed in the vitamin group which increased significantly in the placebo group at the end of 4 months. Malonedialdehyde and protein carbonylation were reduced during the course of treatment with vitamins whereas in the placebo group there was an increase in the level of malondialdehyde. In conclusion, supplementation of water-soluble vitamins in prehypertension reduces oxidative stress and its progression to hypertension.

  3. THE EVOLUTION OF BIOCHEMICAL OXIDATION OF AMMONIA IONS IN SMALL RIVERS WATER

    Directory of Open Access Journals (Sweden)

    Elena Mosanu

    2010-06-01

    Full Text Available Nitrification is the oxidation of ammonia to nitrate, via nitrite and it occupies a central position within the global nitrogen cycle. Nitrifying bacteria are the organisms capable of converting the most reduced form of nitrogen, ammonia, to the most oxidized form, nitrate, but their activity is influenced by pollution level. Starting with the assumption that pollution of small internal water courses in the Republic of Moldova remained severe (phenols, detergents and copper regularly exceed the MACs the work presented in the paper discusses the evolution of ammonia ions nitrification in the water of river Prut tributaries and its correlation with the content of pollutants in water: surface-active substances, Cu, BOD5, COD and other compounds.

  4. Electrochemical oxidation of drug residues in water by the example of tetracycline, gentamicin and Aspirin {sup trademark}

    Energy Technology Data Exchange (ETDEWEB)

    Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Inst. of Water Quality and Waste Management, Univ. of Hannover, Hannover (Germany); Vedenjapin, A.; Baturova, M. [Inst. of Organic Chemistry, Russian Academy of Science, Moscow (Russian Federation)

    2003-07-01

    The electrochemical oxidation as a method to destroy drug residues like Aspirin {sup trademark}, tetracycline or gentamicin in water was investigated with C-Anode (modified by manganese oxides) and Pt Anode. The mechanism of Aspirin {sup trademark} and tetracycline oxidation and the influence of the biocide effect was observed using GC-MS and three different microbiological tests. In general the biological availability increases with progressive oxidation of the antibiotics. (orig.)

  5. Arsenic and antimony removal from drinking water by adsorption on granular ferric oxide.

    Science.gov (United States)

    Sazakli, Eleni; Zouvelou, Stavroula V; Kalavrouziotis, Ioannis; Leotsinidis, Michalis

    2015-01-01

    Arsenic and antimony occur in drinking water due to natural weathering or anthropogenic activities. There has been growing concern about their impact on health. The aim of this study was to assess the efficiency of a granular ferric oxide adsorbent medium to remove arsenic and antimony from drinking water via rapid small-scale column tests (RSSCTs). Three different water matrices - deionized, raw water treated with a reverse osmosis domestic device and raw water - were spiked with arsenic and/or antimony to a concentration of 100 μg L⁻¹. Both elements were successfully adsorbed onto the medium. The loadings until the guideline value was exceeded in the effluent were found to be 0.35-1.63 mg g⁻¹ for arsenic and 0.12-2.11 mg g⁻¹ for antimony, depending on the water matrix. Adsorption of one element was not substantially affected by the presence of the other. Aeration did not affect significantly the adsorption capacity. Granular ferric oxide could be employed for the simultaneous removal of arsenic and antimony from drinking water, whereas full-scale systems should be assessed via laboratory tests before their implementation.

  6. Rigidity, conformation, and solvation of native and oxidized tannin macromolecules in water-ethanol solution

    Science.gov (United States)

    Zanchi, Dražen; Konarev, Petr V.; Tribet, Christophe; Baron, Alain; Svergun, Dmitri I.; Guyot, Sylvain

    2009-06-01

    We studied by light scattering and small angle x-rays scattering (SAXS) conformations and solvation of plant tannins (oligomers and polymers) in mixed water-ethanol solutions. Their structures are not simple linear chains but contain about 6% of branching. Ab initio reconstruction reveals that monomers within a branch are closely bound pairwise. The chains are rather rigid, with the Kuhn length b =13±3 nm, corresponding to about 35 linearly bound monomers. Contribution of solvation layer to SAXS intensity varies in a nonmonotonic way with ethanol content ϕA, which is an indication of amphipathic nature of tannin molecules. Best solvent composition ϕAB is a decreasing function of polymerization degree N, in agreement with increasing water solubility of tannins with N. Polymers longer than b present a power-law behavior I ˜Q-d in the SAXS profile at high momentum transfer Q. The monotonic decrease in d with increasing ϕA (from 2.4 in water to 1.9 in ethanol) points that the tannins are more compact in water than in ethanol, presumably due to attractive intramolecular interactions in water. Tannins were then oxidized in controlled conditions similar to real biological or food systems. Oxidation does not produce any intermolecular condensation, but generates additional intramolecular links. Some oxidation products are insoluble in water rich solvent. For that reason, we identify these species as a fraction of natural tannins called "T1" in the notation of Zanchi et al. [Langmuir 23, 9949 (2007)]. Within the fraction left soluble after oxidation, conformations of polymeric tannins, despite their higher rigidity, remain sensitive to solvent composition.

  7. Oxidation of PCEA nuclear graphite by low water concentrations in helium

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I [ORNL; Mee, Robert [University of Tennessee (UT); Wang, Peng [ORNL; Romanova, Anna V [University of Tennessee, Knoxville (UTK); Burchell, Timothy D [ORNL

    2014-10-01

    Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors best knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam [Velasquez, Hightower, Burnette, 1978]. Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades under qualification for gas-cooled reactors. The Langmuir-Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800 to 1100 oC), and partial pressures of water (15 to 850 Pa) and hydrogen (30 to 150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity of the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another.

  8. Oxidation of PCEA nuclear graphite by low water concentrations in helium

    Energy Technology Data Exchange (ETDEWEB)

    Contescu, Cristian I., E-mail: ContescuCI@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Mee, Robert W. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States); Wang, Peng [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6087 (United States); Romanova, Anna V.; Burchell, Timothy D. [Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN 37996-0525 (United States)

    2014-10-15

    Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors’ knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir–Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800–1100 °C), and partial pressures of water (15–850 Pa) and hydrogen (30–150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another.

  9. Adsorption of Cadmium Ions from Water on Double-walled Carbon Nanotubes/Iron Oxide Composite

    Directory of Open Access Journals (Sweden)

    Karima Seffah

    2017-12-01

    Full Text Available A new material (DWCNT/iron oxide for heavy metals removal was developed by combining the adsorption features of double-walled carbon nanotubes with the magnetic properties of iron oxides. Batch experiments were applied in order to evaluate adsorption capacity of the DWCNT/iron oxide composite for cadmium ions. The influence of operating parameters such as pH value, amount of adsorbent, initial adsorbate concentration and agitation speed was studied. The adsorption capacity of the DWCNT/iron oxide adsorbent for Cd2+ ions was 20.8 mg g-1, which is at the state of the art. The obtained results revealed that DWCNT/iron oxide composite is a very promising adsorbent for removal of Cd2+ ions from water under natural conditions. The advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

  10. Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

    Science.gov (United States)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2015-12-01

    In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H2O2 under UV irradiation (H2O2/UV) and Fenton system under visible light (Fenton/H2O2/Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H2O2/UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H2O2/Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

  11. Evaluating Nanoparticle Breakthrough during Drinking Water Treatment

    Science.gov (United States)

    Chalew, Talia E. Abbott; Ajmani, Gaurav S.; Huang, Haiou

    2013-01-01

    Background: Use of engineered nanoparticles (NPs) in consumer products is resulting in NPs in drinking water sources. Subsequent NP breakthrough into treated drinking water is a potential exposure route and human health threat. Objectives: In this study we investigated the breakthrough of common NPs—silver (Ag), titanium dioxide (TiO2), and zinc oxide (ZnO)—into finished drinking water following conventional and advanced treatment. Methods: NPs were spiked into five experimental waters: groundwater, surface water, synthetic freshwater, synthetic freshwater containing natural organic matter, and tertiary wastewater effluent. Bench-scale coagulation/flocculation/sedimentation simulated conventional treatment, and microfiltration (MF) and ultrafiltration (UF) simulated advanced treatment. We monitored breakthrough of NPs into treated water by turbidity removal and inductively coupled plasma–mass spectrometry (ICP-MS). Results: Conventional treatment resulted in 2–20%, 3–8%, and 48–99% of Ag, TiO2, and ZnO NPs, respectively, or their dissolved ions remaining in finished water. Breakthrough following MF was 1–45% for Ag, 0–44% for TiO2, and 36–83% for ZnO. With UF, NP breakthrough was 0–2%, 0–4%, and 2–96% for Ag, TiO2, and ZnO, respectively. Variability was dependent on NP stability, with less breakthrough of aggregated NPs compared with stable NPs and dissolved NP ions. Conclusions: Although a majority of aggregated or stable NPs were removed by simulated conventional and advanced treatment, NP metals were detectable in finished water. As environmental NP concentrations increase, we need to consider NPs as emerging drinking water contaminants and determine appropriate drinking water treatment processes to fully remove NPs in order to reduce their potential harmful health outcomes. Citation: Abbott Chalew TE, Ajmani GS, Huang H, Schwab KJ. 2013. Evaluating nanoparticle breakthrough during drinking water treatment. Environ Health Perspect 121

  12. Effect of Leaves of Caesalpinia decapetala on Oxidative Stability of Oil-in-Water Emulsions

    Directory of Open Access Journals (Sweden)

    María Gabriela Gallego

    2017-03-01

    Full Text Available Caesalpinia decapetala (Roth Alston (Fabaceae (CD is used in folk medicine to prevent colds and treat bronchitis. This plant has antitumor and antioxidant activity. The antioxidant effects of an extract from Caesalpinia decapetala (Fabaceae were assessed by storage of model food oil-in-water emulsions with analysis of primary and secondary oxidation products. The antioxidant capacity of the plant extract was evaluated by the diphenylpicrylhydrazyl (DPPH, Trolox equivalent antioxidant capacity (TEAC, oxygen radical absorbance capacity (ORAC and ferric reducing antioxidant power (FRAP assays and by electron paramagnetic resonance (EPR spectroscopy. Lyophilized extracts of CD were added at concentrations of 0.002%, 0.02% and 0.2% into oil-in-water emulsions, which were stored for 30 days at 33 ± 1 °C, and then, oxidative stability was evaluated. The CD extract had high antioxidant activity (700 ± 70 µmol Trolox/g dry plant for the ORAC assay, mainly due to its phenolic components: gallic acid, quercetin, catechin, 4-hydroxybenzoic acid and p-coumaric acid. At a concentration of 0.2%, the extract significantly reduced the oxidative deterioration of oil-in-water emulsions. The results of the present study show the possibility of utilizing CD as a promising source of natural antioxidants for retarding lipid oxidation in the food and cosmetic industries.

  13. Effect of Leaves of Caesalpinia decapetala on Oxidative Stability of Oil-in-Water Emulsions

    Science.gov (United States)

    Gallego, María Gabriela; Skowyra, Monika; Gordon, Michael H.; Azman, Nurul Aini Mohd; Almajano, María Pilar

    2017-01-01

    Caesalpinia decapetala (Roth) Alston (Fabaceae) (CD) is used in folk medicine to prevent colds and treat bronchitis. This plant has antitumor and antioxidant activity. The antioxidant effects of an extract from Caesalpinia decapetala (Fabaceae) were assessed by storage of model food oil-in-water emulsions with analysis of primary and secondary oxidation products. The antioxidant capacity of the plant extract was evaluated by the diphenylpicrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays and by electron paramagnetic resonance (EPR) spectroscopy. Lyophilized extracts of CD were added at concentrations of 0.002%, 0.02% and 0.2% into oil-in-water emulsions, which were stored for 30 days at 33 ± 1 °C, and then, oxidative stability was evaluated. The CD extract had high antioxidant activity (700 ± 70 µmol Trolox/g dry plant for the ORAC assay), mainly due to its phenolic components: gallic acid, quercetin, catechin, 4-hydroxybenzoic acid and p-coumaric acid. At a concentration of 0.2%, the extract significantly reduced the oxidative deterioration of oil-in-water emulsions. The results of the present study show the possibility of utilizing CD as a promising source of natural antioxidants for retarding lipid oxidation in the food and cosmetic industries. PMID:28273843

  14. Preparation of water-dispersible graphene by facile surface modification of graphite oxide.

    Science.gov (United States)

    Kuila, Tapas; Khanra, Partha; Bose, Saswata; Kim, Nam Hoon; Ku, Bon-Cheol; Moon, Bongho; Lee, Joong Hee

    2011-07-29

    Water-dispersible graphene was prepared by reacting graphite oxide and 6-amino-4-hydroxy-2-naphthalenesulfonic acid (ANS). X-ray diffraction study showed that the basal reflection (002) peak of graphite oxide was absent in the ANS-functionalized graphene (ANS-G), indicating crystal layer delamination. Ultraviolet-visible spectral data were recorded to assess the solubility of the ANS-G in water. Fourier transform infrared spectral analysis suggested the attachment of ANS molecules to the surface of graphene. Raman and x-ray photoelectron spectroscopy revealed that oxygen functionality in the graphite oxide had been removed during reduction. Atomic force microscopy found that the thickness of ANS-G in water was about 1.8 nm, much higher than that of single layer graphene. Thermal stability measurements also indicated successful removal of oxygen functionality from the graphite oxide and the attachment of thermally unstable ANS to the graphene surfaces. The electrical conductivity of ANS-G, determined by a four-point probe, was 145 S m(-1) at room temperature.

  15. REMOVAL OF ORGANIC DYES FROM CONTAMINATED WATER USING COFE2O4 /REDUCED GRAPHENE OXIDE NANOCOMPOSITE

    Directory of Open Access Journals (Sweden)

    F. Sakhaei

    2016-12-01

    Full Text Available Up to now, lots of materials such as active carbon, iron, manganese, zirconium, and metal oxides have been widely used for removal of dyes from contaminated water. Among these, ferrite nanoparticle is an interesting magnetic material due to its moderate saturation magnetization, excellent chemical stability and mechanical hardness. Graphene, a new class of 2D carbonaceous material with atom thick layer features, has attracted much attention recently due to its high specific surface area. Reduced graphene oxide (rGO has also been of great interest because of its unique properties, which are similar to those of graphene, such as specific surface area, making it an ideal candidate for dye removal. Thus far, few works have been carried out on the preparation of CoFe2O4-rGO composite and its applications in removal of contaminants from water. In this paper, CoFe2O4 reduced graphene oxide nanocomposite was fabricated using hydrothermal process. During the hydrothermal process, the reduction of graphene oxide and growth of CoFe2O4 simultaneously occurred on the carbon basal planes under the conditions generated in the hydrothermal system. The samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy contaminant and UV-Vis spectroscopy as the analytical method. The experimental results suggest that this material has great potential for treating Congo red contaminated water.

  16. Effect of Leaves of Caesalpinia decapetala on Oxidative Stability of Oil-in-Water Emulsions.

    Science.gov (United States)

    Gallego, María Gabriela; Skowyra, Monika; Gordon, Michael H; Azman, Nurul Aini Mohd; Almajano, María Pilar

    2017-03-04

    Caesalpinia decapetala (Roth) Alston (Fabaceae) (CD) is used in folk medicine to prevent colds and treat bronchitis. This plant has antitumor and antioxidant activity. The antioxidant effects of an extract from Caesalpinia decapetala (Fabaceae) were assessed by storage of model food oil-in-water emulsions with analysis of primary and secondary oxidation products. The antioxidant capacity of the plant extract was evaluated by the diphenylpicrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays and by electron paramagnetic resonance (EPR) spectroscopy. Lyophilized extracts of CD were added at concentrations of 0.002%, 0.02% and 0.2% into oil-in-water emulsions, which were stored for 30 days at 33 ± 1 °C, and then, oxidative stability was evaluated. The CD extract had high antioxidant activity (700 ± 70 µmol Trolox/g dry plant for the ORAC assay), mainly due to its phenolic components: gallic acid, quercetin, catechin, 4-hydroxybenzoic acid and p-coumaric acid. At a concentration of 0.2%, the extract significantly reduced the oxidative deterioration of oil-in-water emulsions. The results of the present study show the possibility of utilizing CD as a promising source of natural antioxidants for retarding lipid oxidation in the food and cosmetic industries.

  17. Reaction pattern and mechanism of light induced oxidative water splitting in photosynthesis.

    Science.gov (United States)

    Renger, Gernot; Kühn, Philipp

    2007-06-01

    This mini review is an attempt to briefly summarize our current knowledge on light driven oxidative water splitting in photosynthesis. The reaction leading to molecular oxygen and four protons via photosynthesis comprises thermodynamic and kinetic constraints that require a balanced fine tuning of the reaction coordinates. The mode of coupling between electron (ET) and proton transfer (PT) reactions is shown to be of key mechanistic relevance for the redox turnover of Y(Z) and the reactions within the WOC. The WOC is characterized by peculiar energetics of its oxidation steps in the WOC. In all oxygen evolving photosynthetic organisms the redox state S(1) is thermodynamically most stable and therefore this general feature is assumed to be of physiological relevance. Available information on the Gibbs energy differences between the individual redox states S(i+1) and S(i) and on the activation energies of their oxidative transitions are used to construct a general reaction coordinate of oxidative water splitting in photosystem II (PS II). Finally, an attempt is presented to cast our current state of knowledge into a mechanism of oxidative water splitting with special emphasis on the formation of the essential O-O bond and the active role of the protein environment in tuning the local proton activity that depends on time and redox state S(i). The O-O linkage is assumed to take place within a multistate equilibrium at the redox level of S(3), comprising both redox isomerism and proton tautomerism. It is proposed that one state, S(3)(P), attains an electronic configuration and nuclear geometry that corresponds with a hydrogen bonded peroxide which acts as the entatic state for the generation of complexed molecular oxygen through S(3)(P) oxidation by Y(Z)(ox).

  18. Self-propagating solar light reduction of graphite oxide in water

    Energy Technology Data Exchange (ETDEWEB)

    Todorova, N.; Giannakopoulou, T.; Boukos, N.; Vermisoglou, E. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 153 41 Attikis (Greece); Lekakou, C. [Division of Mechanical, Medical, and Aerospace Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford (United Kingdom); Trapalis, C., E-mail: c.trapalis@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 153 41 Attikis (Greece)

    2017-01-01

    Highlights: • Graphite oxide was partially reduced by solar light irradiation in water media. • No addition of catalysts nor reductive agent were used for the reduction. • Specific capacitance increased stepwise with increase of irradiation time. • Self-propagating reduction of graphene oxide by solar light is suggested. - Abstract: Graphite Oxide (GtO) is commonly used as an intermediate material for preparation of graphene in the form of reduced graphene oxide (rGO). Being a semiconductor with tunable band gap rGO is often coupled with various photocatalysts to enhance their visible light activity. The behavior of such rGO-based composites could be affected after prolonged exposure to solar light. In the present work, the alteration of the GtO properties under solar light irradiation is investigated. Water dispersions of GtO manufactured by oxidation of natural graphite via Hummers method were irradiated into solar light simulator for different periods of time without addition of catalysts or reductive agent. The FT-IR analysis of the treated dispersions revealed gradual reduction of the GtO with the increase of the irradiation time. The XRD, FT-IR and XPS analyses of the obtained solid materials confirmed the transition of GtO to rGO under solar light irradiation. The reduction of the GtO was also manifested by the CV measurements that revealed stepwise increase of the specific capacitance connected with the restoration of the sp{sup 2} domains. Photothermal self-propagating reduction of graphene oxide in aqueous media under solar light irradiation is suggested as a possible mechanism. The self-photoreduction of GtO utilizing solar light provides a green, sustainable route towards preparation of reduced graphene oxide. However, the instability of the GtO and partially reduced GO under irradiation should be considered when choosing the field of its application.

  19. Photosynthetic oxygen evolution: Changes in magnetism of the water-oxidizing enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Sivaraja, M.; Dismukes, G.C. (Princeton Univ., NJ (USA)); Philo, J.S.; Lary, J. (Univ. of Connecticut, Storrs (USA))

    1989-04-26

    Changes in magnetic susceptibility produced by single-turnover flashes of light have been measured for the first time for four of the oxidation states, so-called S states, produced during oxygen evolution in Photosystem II (PSII) complexes of spinach. The data reveal new insights into the structure and bonding of the manganese cluster responsible for catalysis of water oxidation. In samples that have been dark adapted for 15 min or longer to favor population of the resting S{sub 1} state, a train of six flashes increases the paramagnetism on flashes 1, 3, and 5, while no or small increases are observed on flashes 2, 4, and 6. Advancement to the S{sub 1} state does not restore the dark level of S{sub 1} magnetism. This is due to two effects: formation of net paramagnetism from O{sub 2} release on the S{sub 4} {yields} S{sub 0} reaction (scavengeable by glucose oxidase) and a large increase in magnetism for the S{sub 1}(resting) {yields} S{sub 2} reaction, which is not restored without dark readaptation. Comparison of these data with models proposed for the structure of the manganese site reveals that models in which oxidation of substrate water occurs prior to S{sub 4} or oxidation of magnetically isolated Mn ions cannot account for the susceptibility changes observed. The large increase of 17 {mu}{sub B}{sup 2}/PSII observed for the S{sub 1} (resting) {yields} S{sub 2} oxidation is opposite in sign to the decrease in paramagnetism reported for oxidation of synthetic Mn dimers containing the {mu}{sub 2}-oxo-di-{mu}{sub 2}-carboxylato and di-{mu}{sub 2}-oxo-{mu}{sub 2}-carboxylato bridges undergoing the oxidation Mn{sub 2}(III,III) {yields} Mn{sub 2}(III,IV).

  20. Intramolecular Proton Transfer Boosts Water Oxidation Catalyzed by a Ru Complex

    Energy Technology Data Exchange (ETDEWEB)

    Matheu, Roc; Ertem, Mehmed Z.; Benet-Buchholz, Jordi; Coronado, Eugenio; Batista, Victor S.; Sala, Xavier; Llobet, Antoni

    2015-08-26

    We introduce a new family of complexes with the general formula [Run(tda)(py)2]m+ (n = 2, m = 0, 1; n = 3, m = 1, 2+; n = 4, m = 2, 32+), with tda2– being [2,2':6',2''-terpyridine]-6,6''-dicarboxylate, including complex [RuIV(OH)(tda-κ-N3O)(py)2]+, 4H+, which we find to be an impressive water oxidation catalyst, formed by hydroxo coordination to 32+ under basic conditions. The complexes are synthesized, isolated, and thoroughly characterized by analytical, spectroscopic (UV–vis, nuclear magnetic resonance, electron paramagnetic resonance), computational, and electrochemical techniques (cyclic voltammetry, differential pulse voltammetry, coulometry), including solid-state monocrystal X-ray diffraction analysis. In oxidation state IV, the Ru center is seven-coordinated and diamagnetic, whereas in oxidation state II, the complex has an unbonded dangling carboxylate and is six-coordinated while still diamagnetic. With oxidation state III, the coordination number is halfway between the coordination of oxidation states II and IV. Species generated in situ have also been characterized by spectroscopic, computational, and electrochemical techniques, together with the related species derived from a different degree of protonation and oxidation states. 4H+ can be generated potentiometrically, or voltammetrically, from 32+, and both coexist in solution. While complex 32+ is not catalytically active, the catalytic performance of complex 4H+ is characterized by the foot of the wave analysis, giving an impressive turnover frequency record of 8000 s–1 at pH 7.0 and 50 000 s–1 at pH 10.0. Density functional theory calculations provide a complete description of the water oxidation catalytic cycle of 4H+, manifesting the key functional role of the dangling carboxylate in lowering the activation free energies that lead to O–O bond formation.

  1. Induced dipole in vanadium-doped zinc oxide nanosheets and its effects on photoelectrochemical water splitting

    Science.gov (United States)

    Lee, Song Mi; Shin, Sung-Ho; Nah, Junghyo; Lee, Min Hyung

    2017-09-01

    Appropriate control of energy band bending at the interface between semiconductors and electrolytes are closely related to performance of photoelectrochemical (PEC) water splitting. Dipoles formed near the surface of semiconductors induces energy band bending at the interface. Energy band bending control has been demonstrated by employing charged molecules and piezoelectric materials. However, chemical and piezoelectric approaches have demerit of chemical instability and inducement of instantaneous dipole, respectively. To overcome these problems, we adopted the ferroelectric material for PEC water splitting, where spontaneous dipoles in the material can be oriented by applying external electric field. In this work, we hydrothermally synthesized vanadium (V)-doped ferroelectric ZnO nanosheets and employed to systematically investigate the dipole effect on performance of V-doped ZnO PEC for water oxidation. Consequently, positively polarized V-doped ZnO photoanode exhibits 125% enhanced water splitting efficiency compared to negatively polarized ones due to favorable band bending for carrier transport from semiconductor to water.

  2. Development of bioinspired Mn4O4-cubane water oxidation catalysts: lessons from photosynthesis.

    Science.gov (United States)

    Dismukes, G Charles; Brimblecombe, Robin; Felton, Greg A N; Pryadun, Ruslan S; Sheats, John E; Spiccia, Leone; Swiegers, Gerhard F

    2009-12-21

    Hydrogen is the most promising fuel of the future owing to its carbon-free, high-energy content and potential to be efficiently converted into either electrical or thermal energy. The greatest technical barrier to accessing this renewable resource remains the inability to create inexpensive catalysts for the solar-driven oxidation of water. To date, the most efficient system that uses solar energy to oxidize water is the photosystem II water-oxidizing complex (PSII-WOC), which is found within naturally occurring photosynthetic organisms. The catalytic core of this enzyme is a CaMn(4)O(x) cluster, which is present in all known species of oxygenic phototrophs and has been conserved since the emergence of this type of photosynthesis about 2.5 billion years ago. The key features that facilitate the catalytic success of the PSII-WOC offer important lessons for the design of abiological water oxidation catalysts. In this Account, we examine the chemical principles that may govern the PSII-WOC by comparing the water oxidation capabilities of structurally related synthetic manganese-oxo complexes, particularly those with a cubical Mn(4)O(4) core ("cubanes"). We summarize this research, from the self-assembly of the first such clusters, through the elucidation of their mechanism of photoinduced rearrangement to release O(2), to recent advances highlighting their capability to catalyze sustained light-activated electrolysis of water. The [Mn(4)O(4)](6+) cubane core assembles spontaneously in solution from monomeric precursors or from [Mn(2)O(2)](3+) core complexes in the presence of metrically appropriate bidentate chelates, for example, diarylphosphinates (ligands of Ph(2)PO(2)(-) and 4-phenyl-substituted derivatives), which bridge pairs of Mn atoms on each cube face (Mn(4)O(4)L(6)). The [Mn(4)O(4)](6+) core is enlarged relative to the [Mn(2)O(2)](3+) core, resulting in considerably weaker Mn-O bonds. Cubanes are ferocious oxidizing agents, stronger than analogous complexes

  3. Sulfur Poisoning of the Water Gas Shift Reaction on Anode Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Hagen, Anke

    2013-01-01

    resistance increased both in the high and low frequency region, which indicates a strong poisoning of the water gas shift reaction and thus a lack of hydrogen fuel in addition to the poisoning of the electrochemical hydrogen oxidation. All poisoning effects are reversible under the applied operating......Investigation of fuels containing sulfur impurities is important regarding durability of solid oxide fuel cells (SOFC) because they are present in various potential fuels for SOFC applications. The effect of H2S in the ppm range on the performance of state-of-the-art anode supported SOFC at 850...

  4. Formation of bioactive benzofuran via oxidative coupling, using coconut water (Cocos nucifera L. as biocatalyst

    Directory of Open Access Journals (Sweden)

    Luís Cezar Rodrigues

    2017-04-01

    Full Text Available The capacity of simple coconut water, which contains natural peroxidases, to act as a biocatalyst for the oxidative coupling-cyclization of p-(OH-phenylpropanoids, was evaluated in this work. As a result, dimeric forms of isoeugenol (licarin A and methyl p-coumarate (methyl dehydrodicoumarate were obtained. The products of the reactions were characterized by optical rotatory dispersion, and 1H-NMR and 13C-NMR spectroscopy. The oxidative coupling-cyclization mechanism for coniferyl alcohol is proposed.

  5. Biomarkers of oxidative damage in bacteria for the assessment of sanitation efficacy in lettuce wash water.

    Science.gov (United States)

    Cossu, Andrea; Dou, Fang; Young, Glenn M; Nitin, Nitin

    2017-07-01

    In the fresh produce industry, validation of sanitation efficacy is critical to prevent cross-contamination of produce. The current validation approaches are either based on time-consuming plate counting assays or indirect measurements of chemical properties of wash water. In the study, the focus was to identify biomarkers that can provide direct assessment of oxidative damage in bacteria upon exposure to sanitizers in the presence of fresh produce and correlation of these oxidative biomarkers with logarithmic inactivation of bacteria. Two endogenous bacterial biomarkers, protein carbonylation and thiol oxidation, were evaluated for assessing oxidative damage in Escherichia coli O157:H7 and Listeria innocua during sanitation of pre-cut lettuce leaves with NaOCl or H2O2. Results show that NaOCl treatment was more effective than H2O2 for oxidation of both the intracellular thiols and protein carbonylation in the selected strains. Statistical analysis of the measurements illustrates that oxidation of the intracellular thiol induced by NaOCl or H2O2 was correlated with logarithmic reduction of E. coli O157:H7 and L. innocua. In contrast, changes in the protein carbonylation content were not correlated with reduction in bacterial cell viability. In summary, these results provide a novel approach to validate sanitation efficacy for the fresh produce industry.

  6. Oxidation of Oil Sands Process-Affected Water by Potassium Ferrate(VI).

    Science.gov (United States)

    Wang, Chengjin; Klamerth, Nikolaus; Huang, Rongfu; Elnakar, Haitham; Gamal El-Din, Mohamed

    2016-04-19

    This paper investigates the oxidation of oil sands process-affected water (OSPW) by potassium ferrate(VI). Due to the selectivity of ferrate(VI) oxidation, two-ring and three-ring fluorescing aromatics were preferentially removed at doses oxidation achieved 64.0% and 78.4% removal of naphthenic acids (NAs) at the dose of 200 mg/L and 400 mg/L Fe(VI) respectively, and NAs with high carbon number and ring number were removed preferentially. (1)H nuclear magnetic resonance ((1)H NMR) spectra indicated that the oxidation of fluorescing aromatics resulted in the opening of some aromatic rings. Electron paramagnetic resonance (EPR) analysis detected signals of organic radical intermediates, indicating that one-electron transfer is one of the probable mechanisms in the oxidation of NAs. The inhibition effect of OSPW on Vibrio fischeri and the toxicity effect on goldfish primary kidney macrophages (PKMs) were both reduced after ferrate(VI) oxidation. The fluorescing aromatics in OSPW were proposed to be an important contributor to this acute toxicity. Degradation of model compounds with ferrate(VI) was also investigated and the results confirmed our findings in OSPW study.

  7. Ammonia-oxidizing Archaea in the Arctic Ocean and Antarctic coastal waters.

    Science.gov (United States)

    Kalanetra, Karen M; Bano, Nasreen; Hollibaugh, James T

    2009-09-01

    We compared abundance, distributions and phylogenetic composition of Crenarchaeota and ammonia-oxidizing Archaea (AOA) in samples collected from coastal waters west of the Antarctic Peninsula during the summers of 2005 and 2006, with samples from the central Arctic Ocean collected during the summer of 1997. Ammonia-oxidizing Archaea and Crenarchaeota abundances were estimated from quantitative PCR measurements of amoA and 16S rRNA gene abundances. Crenarchaeota and AOA were approximately fivefold more abundant at comparable depths in the Antarctic versus the Arctic Ocean. Crenarchaeota and AOA were essentially absent from the Antarctic Summer Surface Water (SSW) water mass (0-45 m depth). The ratio of Crenarchaeota 16S rRNA to archaeal amoA gene abundance in the Winter Water (WW) water mass (45-105 m depth) of the Southern Ocean was much lower (0.15) than expected and in sharp contrast to the ratio (2.0) in the Circumpolar Deep Water (CDW) water mass (105-3500 m depth) immediately below it. We did not observe comparable segregation of this ratio by depth or water mass in Arctic Ocean samples. A ubiquitous, abundant and polar-specific crenarchaeote was the dominant ribotype in the WW and important in the upper halocline of the Arctic Ocean. Our data suggest that this organism does not contain an ammonia monooxygenase gene. In contrast to other studies where Crenarchaeota populations apparently lacking amoA genes are found in bathypelagic waters, this organism appears to dominate in well-defined, ammonium-rich, near-surface water masses in polar oceans.

  8. Efficient Light-Driven Water Oxidation Catalysis by Dinuclear Ruthenium Complexes.

    Science.gov (United States)

    Berardi, Serena; Francàs, Laia; Neudeck, Sven; Maji, Somnath; Benet-Buchholz, Jordi; Meyer, Franc; Llobet, Antoni

    2015-11-01

    Mastering the light-induced four-electron oxidation of water to molecular oxygen is a key step towards the achievement of overall water splitting to produce alternative solar fuels. In this work, we report two rugged molecular pyrazolate-based diruthenium complexes that efficiently catalyze visible-light-driven water oxidation. These complexes were fully characterized both in the solid state (by X-ray diffraction analysis) and in solution (spectroscopically and electrochemically). Benchmark performances for homogeneous oxygen production have been obtained for both catalysts in the presence of a photosensitizer and a sacrificial electron acceptor at pH 7, and a turnover frequency of up to 11.1 s(-1) and a turnover number of 5300 were obtained after three successive catalytic runs. Under the same experimental conditions with the same setup, the pyrazolate-based diruthenium complexes outperform other well-known water oxidation catalysts owing to both electrochemical and mechanistic aspects. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Dioxygen and water activation processes on multi-Ru-substituted polyoxometalates: comparison with the "blue-dimer" water oxidation catalyst.

    Science.gov (United States)

    Kuznetsov, Aleksey E; Geletii, Yurii V; Hill, Craig L; Morokuma, Keiji; Musaev, Djamaladdin G

    2009-05-20

    Dioxygen and water activation on multi-Ru-substituted polyoxometalates were studied using the B3LYP density functional method. It was shown that the reaction of the Ru(2)-substituted gamma-Keggin polyoxotungstate {gamma-[(H(2)O)Ru(III)-(mu-OH)(2)-Ru(III)(H(2)O)][SiW(10)O(36)]}(4-), I(H(2)O), with O(2) is a 4-electron highly exothermic [DeltaE(gas) = 62.5 (DeltaE(gas) + DeltaG(solv(water)) = 24.6) kcal/mol] process and leads to formation of (H(2)O){gamma-[(O)Ru-(mu-OH)(2)-Ru(O)](H(2)O)[SiW(10)O(36)]}(4-), IV(H(2)O). Both the stepwise (or dissociative) and the concerted (or associative) pathways of this reaction occurring with and without water dissociation, respectively, were examined, and the latter has been found to be kinetically more favorable. It was shown that the first 1e-oxidation is achieved by the H(2)O-to-O(2) substitution, which might occur with a maximum of 23.1 (10.5) kcal/mol barrier and leads to the formation of {gamma-[(OO)Ru-(mu-OH)(2)-Ru(H(2)O)](H(2)O)[SiW(10)O(36)]}(4-), II(H(2)O). The second 1e-oxidation is initiated by the proton transfer from the coordinated water molecule to the superoxide (OO(-)) ligand in II(H(2)O) and is completed upon formation of hydroperoxo-hydroxo intermediate {gamma-[(OOH)Ru-(mu-OH)(2)-Ru(OH)](H(2)O)[SiW(10)O(36)]}(4-), III-1(H(2)O). The final 2e-oxidation occurs upon the proton transfer from the terminal OH-ligand to the Ru-coordinated OOH fragment and is completed at the formation of (H(2)O)...{gamma-[(O)Ru-(mu-OH)(2)-Ru(O)](H(2)O)[SiW(10)O(36)]}(4-), IV(H(2)O), with two Ru=O bonds. Each step in the associative pathway is exothermic and occurs with small energy barriers. During the process, the oxidation state of Ru centers increases from +3 to +4. The resulting IV(H(2)O) with a {Ru(O)-(mu-OH)(2)-Ru(O)} core should be formulated to have the Ru(IV)=O(*) units, rather than the Ru(V)=O groups. The reverse reaction, water oxidation by IV(H(2)O), is found to be highly endothermic and cannot occur; this finding is

  10. Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants.

    Science.gov (United States)

    Zhang, Linyao; Yang, Li; Zhao, Yijun; Zhang, Jiaxu; Feng, Dongdong; Sun, Shaozeng

    2017-07-06

    The water dilute oxy-fuel combustion is a clean combustion technology for near-zero emission power; and the presence of water molecule could have both kinetic and dynamic effects on combustion reactions. The reaction OH + CO → CO 2 + H, one of the most important elementary reactions, has been investigated by extensive electronic structure calculations. And the effects of a single water molecule on CO oxidation have been studied by considering the preformed OH(H 2 O) complex reacts with CO. The results show little change in the reaction pathways, but the additional water molecule actually increases the vibrationally adiabatic energy barriers (V a G ). Further thermal rate constant calculations in the temperature range of 200 to 2000 K demonstrate that the total low-pressure limit rate constant for the water assisted OH(H 2 O) + CO → CO 2 + H 2 O + H reaction is 1-2 orders lower than that of the water unassisted one, which is consistent with the change of V a G . Therefore, the hydrated radical OH(H 2 O) would actually slow down the oxidation of CO. Meanwhile, comparisons show that the M06-2X/aug-cc-pVDZ method gives a much better estimation in energy and thus is recommended to be employed for direct dynamics simulations.

  11. Photocatalytic Oxidation of Oil Contaminated Water Using TiO2/UV

    Science.gov (United States)

    Vargas Solla, Monica; Romero Rojas, Jairo

    2017-04-01

    Currently, oil is one of the most used energy sources all around the world, for example to make motor engines work. That prevailing usage of oil is the reason why water sources are under serious pollution risks with compounds that are hard to remove, such as hydrocarbons. There are a few water treatment processes known as Advanced Oxidation Processes, which search for a way to treat polluted water with toxic refractory compounds, to make its reuse more feasible and to avoid or at least appease the injurious effects of pollution over ecosystems. A heterogeneous photocatalysis water treatment technology, sorted as an Advanced Oxidation Process, which is intended to treat refractory compound polluted water by the use of TiO2 and UV light, is presented in this investigation. The evidence about its efficiency in hydrocarbon removal from used motor oil polluted water, since it is an extremely important pollutant due to its complexity, toxicity and recalcitrant characteristics, is also presented through COD, Oil and Grease and Hydrocarbons analysis.

  12. Theoretical study of catalytic mechanism for single-site water oxidation process.

    Science.gov (United States)

    Lin, Xiangsong; Hu, Xiangqian; Concepcion, Javier J; Chen, Zuofeng; Liu, Shubin; Meyer, Thomas J; Yang, Weitao

    2012-09-25

    Water oxidation is a linchpin in solar fuels formation, and catalysis by single-site ruthenium complexes has generated significant interest in this area. Combining several theoretical tools, we have studied the entire catalytic cycle of water oxidation for a single-site catalyst starting with [Ru(II)(tpy)(bpm)(OH(2))](2+) (i.e., [Ru(II)-OH(2)](2+); tpy is 2,2':6',2''-terpyridine and bpm is 2,2'-bypyrimidine) as a representative example of a new class of single-site catalysts. The redox potentials and pK(a) calculations for the first two proton-coupled electron transfers (PCETs) from [Ru(II)-OH(2)](2+) to [Ru(IV) = O](2+) and the following electron-transfer process to [Ru(V) = O](3+) suggest that these processes can proceed readily in acidic or weakly basic conditions. The subsequent water splitting process involves two water molecules, [Ru(V) = O](3+) to generate [Ru(III)-OOH](2+), and H(3)O(+) with a low activation barrier (~10 kcal/mol). After the key O-O bond forming step in the single-site Ru catalysis, another PECT process oxidizes [Ru(III)-OOH](2+) to [Ru(IV)-OO](2+) when the pH is lower than 3.7. Two possible forms of [Ru(IV)-OO](2+), open and closed, can exist and interconvert with a low activation barrier (catalytic cycle. This understanding is helpful in the design of new catalysts for water oxidation.

  13. Chemical oxidation methods in the closure of paper mill water circulations; Hapetustekniikoiden kaeyttoe metsaeteollisuuden vesikiertojen sulkemisessa - EKT 04

    Energy Technology Data Exchange (ETDEWEB)

    Laari, A.; Kallas, J. [Lappeenranta Univ. of Technology (Finland); Korhonen, S. [Kuopio Univ. (Finland); Tuhkanen, T. [Mikkelin Ammattikorkeakoulu, Mikkeli (Finland)

    1998-12-31

    When water circulations are closed some harmful compounds tend to accumulate in the circulation waters. These compounds include lipophilic extractives, like resin and fatty acids, triglycerides and sterols, but also other compounds, like lignins, lignans and sugars. Microbial growth will increase due to elevated organic concentrations. The purpose of this project is to find out the possibilities of the use of ozonation and wet oxidation in the treatment of paper mill water circulations. In chemical oxidation organic matter is destroyed in oxidation reactions. Especially lipophilic extractives are selectively oxidated by ozone. Chemical oxidation reactions are carried out in gas-liquid reactors, where ozone or oxygen are transferred from gas to liquid phase where the oxidation reactions happen. One target of the project is to estimate kinetic parameters for different groups of compounds on the basis of experimental data. Kinetic parameters are then used in modelling of reactors and in estimation of process costs. (orig.)

  14. Laser-induced breakdown spectroscopy of light water reactor simulated used nuclear fuel: Main oxide phase

    Science.gov (United States)

    Campbell, Keri R.; Judge, Elizabeth J.; Barefield, James E.; Colgan, James P.; Kilcrease, David P.; Czerwinski, Ken R.; Clegg, Samuel M.

    2017-07-01

    The analysis of light water reactor simulated used nuclear fuel using laser-induced breakdown spectroscopy (LIBS) is explored using a simplified version of the main oxide phase. The main oxide phase consists of the actinides, lanthanides, and zirconium. The purpose of this study is to develop a rapid, quantitative technique for measuring zirconium in a uranium dioxide matrix without the need to dissolve the material. A second set of materials including cerium oxide is also analyzed to determine precision and limit of detection (LOD) using LIBS in a complex matrix. Two types of samples are used in this study: binary and ternary oxide pellets. The ternary oxide, (U,Zr,Ce)O2 pellets used in this study are a simplified version the main oxide phase of used nuclear fuel. The binary oxides, (U,Ce)O2 and (U,Zr)O2 are also examined to determine spectral emission lines for Ce and Zr, potential spectral interferences with uranium and baseline LOD values for Ce and Zr in a UO2 matrix. In the spectral range of 200 to 800 nm, 33 cerium lines and 25 zirconium lines were identified and shown to have linear correlation values (R2) > 0.97 for both the binary and ternary oxides. The cerium LOD in the (U,Ce)O2 matrix ranged from 0.34 to 1.08 wt% and 0.94 to 1.22 wt% in (U,Ce,Zr)O2 for 33 of Ce emission lines. The zirconium limit of detection in the (U,Zr)O2 matrix ranged from 0.84 to 1.15 wt% and 0.99 to 1.10 wt% in (U,Ce,Zr)O2 for 25 Zr lines. The effect of multiple elements in the plasma and the impact on the LOD is discussed.

  15. Spectroscopic Characterization of the Water Oxidation Intermediates in the Blue Dimer Ru-Based Catalyst for Artificial Photosynthesis

    Science.gov (United States)

    Moonshiram, Dooshaye; Pushkar, Yulia; Jurss, Jonah; Concepcion, Javier; Meyer, Thomas; Zakharova, Taisiya; Alperovich, Igor

    2012-02-01

    Utilization of sunlight requires solar capture, light-to-energy conversion and storage. One effective way to store energy is to convert it into chemical energy by fuel-forming reactions, such as water splitting into hydrogen and oxygen. Ruthenium complexes are among few molecular-defined catalysts capable of water splitting. Mechanistic insights about such catalysts can be acquired by spectroscopic analysis of short-lived intermediates of catalytic water oxidation. Use of techniques such as EPR and X-ray absorption spectroscopy (XAS) are used to determine electronic requirements of catalytic water oxidation. About 30 years ago Meyer and coworkers reported first ruthenium-based catalyst for water oxidation, the ``blue dimer''. We performed EPR studies and characterized structures and electronic configurations of intermediates of water oxidation by the ``blue dimer''. Intermediates were prepared chemically by oxidation of Ru-complexes with defined number of Ce (IV) equivalents and freeze-quenched at controlled times. Changes in oxidation state of Ru atom were detected by XANES at Ru K-edges. K-edges are sensitive to changes in Ru oxidation state for Blue Dimer [3,3]^4+, [3,4]^4+, [3,4]'^4+ and [4,5]^3+ allowing a clear assignment of Ru oxidation state in intermediates. EXAFS demonstrated structural changes.

  16. Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

    Directory of Open Access Journals (Sweden)

    Seungho Cho

    2014-01-01

    Full Text Available Photoelectrochemical (PEC water splitting to hydrogen is an attractive method for capturing and storing the solar energy in the form of chemical energy. Metal oxides are promising photoanode materials due to their low-cost synthetic routes and higher stability than other semiconductors. In this paper, we provide an overview of recent efforts to improve PEC efficiencies via applying a variety of fabrication strategies to metal oxide photoanodes including (i size and morphology-control, (ii metal oxide heterostructuring, (iii dopant incorporation, (iv attachments of quantum dots as sensitizer, (v attachments of plasmonic metal nanoparticles, and (vi co-catalyst coupling. Each strategy highlights the underlying principles and mechanisms for the performance enhancements.

  17. Lindqvist Polyoxoniobate Ion-Assisted Electrodeposition of Cobalt and Nickel Water Oxidation Catalysts.

    Science.gov (United States)

    Liu, YuPing; Guo, Si-Xuan; Ding, Liang; Ohlin, C André; Bond, Alan M; Zhang, Jie

    2015-08-05

    A method has been developed for the efficient electrodeposition of cobalt and nickel nanostructures with the assistance of the Lindqvist ion [Nb6O19](8-). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry, and a range of electrochemical techniques have been used to characterize the morphology, composition, catalytic water oxidation activity and stability of the films in alkaline solution. SEM images show that films consisting of nanoparticles with diameters of ca. 30 to 40 nm are formed after 40-50 potential cycles of deposition. Nb and Co/Ni are detected in the films by EDX. ICP-MS results show an elemental ratio of 1:1 for Co:Nb and 1:3 for Ni:Nb, respectively. Raman spectra reveal the presence of both [Nb6O19](8-) and Co(OH)2/Ni(OH)2. The films exhibit excellent stability and efficiency for electrocatalytic water oxidation in alkaline solution. Turnover frequencies of 12.9 and 13.2 s(-1) were determined by rotating ring disk electrode voltammetry at an overpotential of 480 mV for Co and Ni films, respectively. Fourier transformed large amplitude alternating current (FTAC) voltammetry reveals an additional underlying oxidation process for Co under catalytic turnover conditions, which indicates that a Co(IV) species is involved in the efficient catalytic water oxidation reactions. FTAC voltammetric data also suggest that the Ni films undergoes a clear phase transformation upon aging in aqueous 1 M NaOH and the electrogenerated higher oxidation state Ni from β-NiOOH is the more active form of the catalyst.

  18. Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite.

    Science.gov (United States)

    Qiu, Jingjing; Hajibabaei, Hamed; Nellist, Michael R; Laskowski, Forrest A L; Hamann, Thomas W; Boettcher, Shannon W

    2017-09-27

    Electrocatalysts improve the efficiency of light-absorbing semiconductor photoanodes driving the oxygen evolution reaction, but the precise function(s) of the electrocatalysts remains unclear. We directly measure, for the first time, the interface carrier transport properties of a prototypical visible-light-absorbing semiconductor, α-Fe2O3, in contact with one of the fastest known water oxidation catalysts, Ni0.8Fe0.2O x , by directly measuring/controlling the current and/or voltage at the Ni0.8Fe0.2O x catalyst layer using a second working electrode. The measurements demonstrate that the majority of photogenerated holes in α-Fe2O3 directly transfer to the catalyst film over a wide range of conditions and that the Ni0.8Fe0.2O x is oxidized by photoholes to an operating potential sufficient to drive water oxidation at rates that match the photocurrent generated by the α-Fe2O3. The Ni0.8Fe0.2O x therefore acts as both a hole-collecting contact and a catalyst for the photoelectrochemical water oxidation process. Separate measurements show that the illuminated junction photovoltage across the α-Fe2O3|Ni0.8Fe0.2O x interface is significantly decreased by the oxidation of Ni(2+) to Ni(3+) and the associated increase in the Ni0.8Fe0.2O x electrical conductivity. In sum, the results illustrate the underlying operative charge-transfer and photovoltage generation mechanisms of catalyzed photoelectrodes, thus guiding their continued improvement.

  19. Molybdenum oxide nanocolloids prepared by an external field-assisted laser ablation in water

    Science.gov (United States)

    Spadaro, Salvatore; Bonsignore, Martina; Fazio, Enza; Cimino, Francesco; Speciale, Antonio; Trombetta, Domenico; Barreca, Francesco; Saija, Antonina; Neri, Fortunato

    2018-01-01

    he synthesis of extremely stable molybdenum oxide nanocolloids by pulsed laser ablation was studied. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products. A focused picosecond pulsed laser beam was used to ablate a solid molybdenum target immersed in deionized water. Molybdenum oxide nearly spherical nanoparticles with dimensions within few nanometers (20-100 nm) are synthesized when the ablation processes were carried out, in water, at room temperature and 80°C. The application of an external electric field during the ablation process induces a nanostructures reorganization, as indicated by Scanning-Transmission Electron Microscopy images analysis. The ablation products were also characterized by some spectroscopic techniques: conventional UV-vis optical absorption, atomic absorption, dynamic light scattering, micro-Raman and X-ray photoelectron spectroscopies. Finally, NIH/3T3 mouse fibroblasts were used to evaluate cell viability by the sulforhodamine B assay

  20. Molybdenum oxide nanocolloids prepared by an external field-assisted laser ablation in water

    Directory of Open Access Journals (Sweden)

    Spadaro Salvatore

    2018-01-01

    Full Text Available he synthesis of extremely stable molybdenum oxide nanocolloids by pulsed laser ablation was studied. This green technique ensures the formation of contaminant-free nanostructures and the absence of by-products. A focused picosecond pulsed laser beam was used to ablate a solid molybdenum target immersed in deionized water. Molybdenum oxide nearly spherical nanoparticles with dimensions within few nanometers (20-100 nm are synthesized when the ablation processes were carried out, in water, at room temperature and 80°C. The application of an external electric field during the ablation process induces a nanostructures reorganization, as indicated by Scanning-Transmission Electron Microscopy images analysis. The ablation products were also characterized by some spectroscopic techniques: conventional UV-vis optical absorption, atomic absorption, dynamic light scattering, micro-Raman and X-ray photoelectron spectroscopies. Finally, NIH/3T3 mouse fibroblasts were used to evaluate cell viability by the sulforhodamine B assay

  1. Carrier dynamics of a visible-light-responsive Ta3N5 photoanode for water oxidation

    KAUST Repository

    Ziani, Ahmed

    2015-01-01

    The physicochemical properties of a tantalum nitride (Ta3N5) photoanode were investigated in detail to understand the fundamental aspects associated with the photoelectrochemical (PEC) water oxidation. The Ta3N5 thin films were synthesized using DC magnetron sputtering followed by annealing in air and nitridation under ammonia (NH3). A polycrystalline structure with a dense morphology of the monoclinic Ta3N5 films was obtained. A relatively low absorption coefficient (104 to 105 cm-1) in the visible light range was measured for Ta3N5, consistent with the nature of the indirect band-gap. Ultra-fast spectroscopic measurements revealed that the Ta3N5 with different thicknesses films possess low transport properties and fast carrier recombination (<10 ps). These critical kinetic properties of Ta3N5 as a photoanode may necessitate high overpotentials to achieve appreciable photocurrents for water oxidation (onset ∼0.6 V vs. RHE). This journal is

  2. Bioinspired Cobalt-Citrate Metal-Organic Framework as an Efficient Electrocatalyst for Water Oxidation.

    Science.gov (United States)

    Jiang, Jing; Huang, Lan; Liu, Xiaomin; Ai, Lunhong

    2017-03-01

    Efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts are closely associated with many important energy conversion technologies. Herein, we first report an oxygen-evolving cobalt-citrate metal-organic framework (MOF, UTSA-16) for highly efficient electrocatalytic water oxidation. Benefiting from synergistic cooperation of intrinsic open porous structure, in situ formed high valent cobalt species, and existing Co4O4 cubane, the UTSA-16 exhibits excellent activity toward OER catalysis in alkaline medium. The UTSA-16 needs only 408 mV to offer a current density of 10 mA cm-2 for OER catalysis, which is superior to that of most MOF-based electrocatalysts and the standard Co3O4 counterpart. The present finding provides a better understanding of electroactive MOFs for water oxidation.

  3. Fullerene-reduced graphene oxide composites obtained by ultrashort laser ablation of fullerite in water

    Energy Technology Data Exchange (ETDEWEB)

    De Bonis, A., E-mail: angela.debonis@unibas.it [Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano, 10-85100, Potenza (Italy); Curcio, M. [Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano, 10-85100, Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050, Tito Scalo (PZ) (Italy); Rau, J.V. [CNR-ISM, Via del Fosso del Cavaliere, 100-00133, Rome (Italy); Galasso, A.; Teghil, R. [Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano, 10-85100, Potenza (Italy)

    2015-05-01

    Highlights: • Laser ablation of a fullerite target in water performed by an ultra-short laser source has been reported. • The formation of reduced graphene oxide has been described considering the laser ablation in liquid mechanism. • Fullerene-reduced graphene oxide composite, in the form of self assembled microtubes, has been described. - Abstract: The laser ablation in liquid of carbon-based solid targets is of particular interest thanks to the possibility of obtaining different carbon allotropes by varying the experimental parameters employed. The ablation of a fullerite target in water using a frequency-doubled Nd:glass laser source with a pulse duration of 250 fs and a frequency repetition rate of 10 Hz is presented. The obtained products have been characterized by transmission electron and atomic force microscopies and by X-ray photoelectron and micro-Raman spectroscopies. During the femtosecond laser ablation, the collapse of fullerene cages has been considered with the consequent formation of graphene oxide (GO) and its successive hydrogenation. The process of self-assembling in microtube structures of the formed reduced graphene oxide-fullerene composites has then been reported.

  4. Ligand Fluorination to Optimize Preferential Oxidation (PROX) of Carbon Monoxide by Water-Soluble Rhodium Porphyrins

    Science.gov (United States)

    Biffinger, Justin C.; Uppaluri, ShriHarsha; Sun, Haoran

    2011-01-01

    Catalytic, low temperature preferential oxidation (PROX) of carbon monoxide by aqueous [5,10,15,20-tetrakis(4-sulfonatophenyl)-2,3,7,8,12,13,17,18-octafluoroporphyrinato]rhodium(III) tetrasodium salt, (1[Rh(III)]) and [5,10,15,20-tetrakis(3-sulfonato-2,6-difluorophenyl)-2,3,7,8,12,13,17,18-octafluoroporphyrinato]rhodium(III) tetrasodium salt, (2[Rh(III)]) is reported. The PROX reaction occurs at ambient temperature in buffered (4 ≤ pH ≤ 13) aqueous solutions. Fluorination on the porphyrin periphery is shown to increase the CO PROX reaction rate, shift the metal centered redox potentials, and acidify ligated water molecules. Most importantly, β-fluorination increases the acidity of the rhodium hydride complex (pKa = 2.2 ± 0.2 for 2[Rh-D]); the dramatically increased acidity of the Rh(III) hydride complex precludes proton reduction and hydrogen activation near neutral pH, thereby permitting oxidation of CO to be unaffected by the presence of H2. This new fluorinated water-soluble rhodium porphyrin-based homogenous catalyst system permits preferential oxidation of carbon monoxide in hydrogen gas streams at 308 °K using dioxygen or a sacrificial electron acceptor (indigo carmine) as the terminal oxidant. PMID:21949596

  5. Oxidative treatments used to make water potable; Tratamientos oxidativos en la potabilizacion del agua

    Energy Technology Data Exchange (ETDEWEB)

    Gracia, R.; Cortes, S.; Sarasa, J.; Ormad, P.; Ovelleiro, J. L. [Universidad de Zaragoza (Spain)

    1999-08-01

    It is studied with pre-ozonation replacing pre-chlorination during drinking-water treatment for improving the water quality since the discovery of potentially harmful chlorination by products such as trihalomethanes (THM). Raw Ebro river (Spain) water is ozonated in the presence of titanium dioxide (TiO{sub 2}) supported on alumina as a catalyst and later chlorinated. It is shown that using this catalyst during ozonation of the natural water allowed reductions in organic matter and therefore in THM formation. Characterization of the organic compounds resulting from oxidation techniques was made by concentrating the sample through liquid-liquid extraction, along with the gas chromatography/mass spectrometry (GC/MS). THMs were measured by an head space connected to a gas chromatograph equipped with an electron capture detector (GC/ECD). (Author) 12 refs.

  6. Reduced Graphene Oxide Bipolar Membranes for Integrated Solar Water Splitting in Optimal pH.

    Science.gov (United States)

    McDonald, Michael B; Bruce, Jared P; McEleney, Kevin; Freund, Michael S

    2015-08-24

    The integration of light absorbers and catalysts for the water splitting process requires a membrane capable of both ion and electron management and product separation to realize efficient solar fuels systems. Bipolar membranes can maintain a pH gradient for optimal reaction conditions by the dissociation of water. Such membranes that contain graphene in the interfacial layer are fabricated by the chemical reduction of a uniformly deposited graphene oxide layer to convert sp(3) catalyst regions to sp(2) conductive regions. The resulting electrical and water dissociation properties are optimized by adjusting the exposure conditions, and treatments of less than 5 min render an interface that exceeds the conductivity requirements for integrated solar water splitting and increases the overpotential by graphene and Si microwires, and we found that efficient Ohmic junctions are possible. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Theoretical study of water oxidation and reduction mechanisms by aminopyridine first row transition metal catalysts

    OpenAIRE

    Acuña-Parés, Ferran

    2016-01-01

    One of the major current scientific goals is the development of renewable energy sources. An effective alternative to fossil fuels consists in the conversion of the sunlight energy into chemical fuels. The molecular hydrogen from water is considered the most promising energy carrier. In the natural photosynthesis the solar energy is stored into the carbohydrate chemical bonds derived from water and CO2. The key step of this process is the photo-oxidation of H2O molecules into O2, which provi...

  8. Implementing supercritical water oxidation technology in a lunar base environmental control/life support system

    Science.gov (United States)

    Meyer Sedej, M.

    1985-01-01

    A supercritical water oxidation system (SCWOS) offers several advantages for a lunar base environmental control/life support system (ECLSS) compared to an ECLSS based on Space Station technology. In supercritically heated water (630 K, 250 atm) organic materials mix freely with oxygen and undergo complete combustion. Inorganic salts lose solubility and precipitate out. Implementation of SCWOS can make an ECLSS more efficient and reliable by elimination of several subsystems and by reduction in potential losses of life support consumables. More complete closure of the total system reduces resupply requirements from the earth, a crucial cost item in maintaining a lunar base.

  9. Antioxidant effect of water and acetone extracts of Fucus vesiculosuson oxidative stability of skin care emulsions

    DEFF Research Database (Denmark)

    Poyato, Candelaria; Thomsen, Birgitte Raagaard; Hermund, Ditte Baun

    2017-01-01

    A water and an acetone extract of the Icelandic brown algae Fucus vesiculosus were evaluated as potential natural sources of antioxidant compounds in skin care emulsions. To assess their efficacy in inhibiting lipid oxidation caused by photo- or thermoxidation, they were stored in darkness and room...... temperature. High temperature also caused greater increments in the droplet size of the emulsions. The analysis of the tocopherol content, peroxide value and volatile compounds during the storage revealed that, whereas both water and acetone extracts showed (at 2 mg/g of emulsion) protective effect against...

  10. Enzyme-inspired functional surfactant for aerobic oxidation of activated alcohols to aldehydes in water

    KAUST Repository

    Chen, Batian

    2015-02-06

    We describe an enzyme-inspired catalytic system based on a rationally designed multifunctional amphiphile. The resulting micelles feature metal-binding sites and stable free radical moieties as well as fluorous pockets that attract and preconcentrate molecular oxygen. In the presence of copper ions, the micelles effect chemoselective aerobic alcohol oxidation under ambient conditions in water, a transformation that is challenging to achieve nonenzymatically.

  11. A new water oxidation catalyst: lithium manganese pyrophosphate with tunable Mn valency.

    Science.gov (United States)

    Park, Jimin; Kim, Hyunah; Jin, Kyoungsuk; Lee, Byung Ju; Park, Yong-Sun; Kim, Hyungsub; Park, Inchul; Yang, Ki Dong; Jeong, Hui-Yun; Kim, Jongsoon; Hong, Koo Tak; Jang, Ho Won; Kang, Kisuk; Nam, Ki Tae

    2014-03-19

    The development of a water oxidation catalyst has been a demanding challenge for the realization of overall water-splitting systems. Although intensive studies have explored the role of Mn element in water oxidation catalysis, it has been difficult to understand whether the catalytic capability originates mainly from either the Mn arrangement or the Mn valency. In this study, to decouple these two factors and to investigate the role of Mn valency on catalysis, we selected a new pyrophosphate-based Mn compound (Li2MnP2O7), which has not been utilized for water oxidation catalysis to date, as a model system. Due to the monophasic behavior of Li2MnP2O7 with delithiation, the Mn valency of Li(2-x)MnP2O7 (x = 0.3, 0.5, 1) can be controlled with negligible change in the crystal framework (e.g., volume change ~1%). Moreover, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, ex-situ X-ray absorption near-edge structure, galvanostatic charging-discharging, and cyclic voltammetry analysis indicate that Li(2-x)MnP2O7 (x = 0.3, 0.5, 1) exhibits high catalytic stability without additional delithiation or phase transformation. Notably, we observed that, as the averaged oxidation state of Mn in Li(2-x)MnP2O7 increases from 2 to 3, the catalytic performance is enhanced in the series Li2MnP2O7 catalyst under neutral conditions with controlled Mn valency and atomic arrangement.

  12. [Removal of arsenic (II) by ferrate oxidation-coagulation from drinking water].

    Science.gov (United States)

    Yuan, Bao-ling; Li, Kun-lin; Deng, Lin-li; Zhang, Zhi-dong

    2006-02-01

    Ferrate is multi-function agent in water treatment and shows great oxidizing ability and excellent purifying effect. This experiment evaluated the performance of ferrate for arsenic removal. Experimental results show that the best rate of ferrate and arsenic (III) is 15:1, the efficiency of As removal can be achieved 98%, and the residual concentration of As3 + is removal arsenic. This method is easy, very effective comparing with ferric method and KMnO4-Ferric method.

  13. Oxidation of substituted phenols in supercritical water. Final technical report, September 1992--August 1996

    Energy Technology Data Exchange (ETDEWEB)

    Savage, P.E.

    1996-11-01

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or reused. Oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of model pollutants in supercritical water. The decomposition of cresols, hydroxybenzaidehydes, nitrophenols, and benzenediols was studied in dilute aqueous solutions in both the presence and absence of oxygen at 460{degrees}C and 250 atm. Experimental data from the oxidation of these compounds were fit to global, power-law rate expressions. The resulting rate laws showed that the reactivity of the different isomers at 460{degrees}C was in the order of ortho > para > meta for cresols and hydroxybenzaldehydes. Moreover, the CHO-substituted phenol was more reactive than the analogous CH{sub 3}-substituted phenol, and all of these substituted phenols were more reactive than phenol itself. Identifying and quantifying the reaction products of incomplete oxidation allowed us to assemble a general reaction network for the oxidation of cresols in supercritical water. This network comprises parallel primary paths to phenol, to a hydroxybenzaldehyde, and to ring-opening products. The hydroxybenzaldehyde reacts through parallel paths to phenol and to ring-opening products. Phenol also reacts via two parallel paths, but these lead to phenol dimers; and ring-opening products. The dimers are eventually converted to ring-opening products, and the ring-opening products are ultimately converted to CO{sub 2} The relative rates of the different paths in the reaction network are strong functions of the location of the substituent on the phenolic ring.

  14. Chlorination of bromide-containing waters: enhanced bromate formation in the presence of synthetic metal oxides and deposits formed in drinking water distribution systems.

    Science.gov (United States)

    Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe

    2013-09-15

    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate > sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Chlorination of bromide-containing waters: Enhanced bromate formation in the presence ofsynthetic metal oxides and deposits formed indrinking water distribution systems

    KAUST Repository

    Liu, Chao

    2013-09-01

    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate>>sulfate>bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. © 2013 Elsevier Ltd.

  16. QSAR models for the removal of organic micropollutants in four different river water matrices

    KAUST Repository

    Sudhakaran, Sairam

    2012-04-01

    Ozonation is an advanced water treatment process used to remove organic micropollutants (OMPs) such as pharmaceuticals and personal care products (PPCPs). In this study, Quantitative Structure Activity Relationship (QSAR) models, for ozonation and advanced oxidation process (AOP), were developed with percent-removal of OMPs by ozonation as the criterion variable. The models focused on PPCPs and pesticides elimination in bench-scale studies done within natural water matrices: Colorado River, Passaic River, Ohio River and Suwannee synthetic water. The OMPs removal for the different water matrices varied depending on the water quality conditions such as pH, DOC, alkalinity. The molecular descriptors used to define the OMPs physico-chemical properties range from one-dimensional (atom counts) to three-dimensional (quantum-chemical). Based on a statistical modeling approach using more than 40 molecular descriptors as predictors, descriptors influencing ozonation/AOP were chosen for inclusion in the QSAR models. The modeling approach was based on multiple linear regression (MLR). Also, a global model based on neural networks was created, compiling OMPs from all the four river water matrices. The chemically relevant molecular descriptors involved in the QSAR models were: energy difference between lowest unoccupied and highest occupied molecular orbital (E LUMO-E HOMO), electron-affinity (EA), number of halogen atoms (#X), number of ring atoms (#ring atoms), weakly polar component of the solvent accessible surface area (WPSA) and oxygen to carbon ratio (O/C). All the QSAR models resulted in a goodness-of-fit, R 2, greater than 0.8. Internal and external validations were performed on the models. © 2011 Elsevier Ltd.

  17. Role of Oxygen Functionalities in Graphene Oxide Architectural Laminate Subnanometer Spacing and Water Transport.

    Science.gov (United States)

    Amadei, Carlo Alberto; Montessori, Andrea; Kadow, Julian P; Succi, Sauro; Vecitis, Chad D

    2017-04-18

    Active research in nanotechnology contemplates the use of nanomaterials for environmental engineering applications. However, a primary challenge is understanding the effects of nanomaterial properties on industrial device performance and translating unique nanoscale properties to the macroscale. One emerging example consists of graphene oxide (GO) membranes for separation processes. Thus, here we investigate how individual GO properties can impact GO membrane characteristics and water permeability. GO chemistry and morphology were controlled with easy-to-implement photoreduction and sonication techniques and were quantitatively correlated, offering a valuable tool for accelerating characterization. Chemical GO modification allows for fine control of GO oxidation state, allowing control of GO architectural laminate (GOAL) spacing and permeability. Water permeability was measured for eight GOALs characterized by different GOAL chemistry and morphology and indicates that GOAL nanochannel height dictates water transport. The experimental outputs were corroborated with mesoscale water transport simulations of relatively large domains (thousands of square nanometers) and indicate a no-slip Darcy-like behavior inside the GOAL nanochannels. The experimental and simulation evidence presented in this study helps create a clearer picture of water transport in GOAL and can be used to rationally design more effective and efficient GO membranes.

  18. Water dissociation and CO oxidation over Au/anatase catalyst. A DFT-D2 study

    Science.gov (United States)

    Saqlain, Muhammad Adnan; Hussain, Akhtar; Siddiq, Muhammad; Leitão, Alexandre A.

    2018-03-01

    With the help of DFT-D2 methodology, we have investigated the adsorption of water on clean anatase(001) and Au/anatase(001). In the former case, adsorption energies of H2O differ to small extent computed employing GGA = PW91 and DFT-D2 methods. While the GGA = PW91 predicts that water would desorb close to 650 K on the TiO2 surface, the DFT-D2 predicts that desorption is most likely to occur above 700 K. A comparison of water adsorption on TiO2 and Au/TiO2 surfaces shows that the TiO2 prefers dimer adsorption whereas the Au/TiO2 prefers monomer adsorption. We found that the diffusion of surface hydroxyls on to the Au cluster from the Au/TiO2 periphery is unlikely and it seems that the CO oxidation would occur at the Au/TiO2 boundary. The results show that water dissociation and CO oxidation steps occur easily on Au/TiO2 indicating that this could be good alternative catalyst for water gas shift reaction industry.

  19. Potential climate change effects on water tables and pyrite oxidation in headwater catchments in Colorado

    Science.gov (United States)

    Webb, Richard M.; Mast, M. Alisa; Manning, Andrew H.; Clow, David W.; Campbell, Donald H.; Medley, C. Nicholas; Patterson, Glenn; Parker, Melanie J.

    2011-01-01

    A water, energy, and biogeochemical model (WEBMOD) was constructed to simulate hydrology and pyrite oxidation for the period October 1992 through September 1997. The hydrologic model simulates processes in Loch Vale, a 6.6-km² granitic watershed that drains the east side of the Continental Divide. Parameters describing pyrite oxidation were derived sulfate concentrations measured in pore water and stream water in Handcart Gulch, a naturally acidic watershed in the Colorado Mineral Belt. Average monthly differences in precipitation and temperature between current and future climates, as predicted by using six global circulation models and three carbondioxide emission scenarios, were input into WEBMOD to identify possible shifts in the quantity and quality of the water flowing from the watershed for the period 2005 through 2100. Initial results suggest that increased air temperatures will result in earlier snowmelt compared to current conditions. Average sulfate concentrations and acidity in streams draining hydrothermally altered terrain may decrease as water tables rise in response to greater overall precipitation and earlier snowmelt, although a net increase of sulfate load was simulated as a result of greater overall discharge. Evapotranspiration is expected to increase but not enough to offset the increase in precipitation.

  20. Evaluating the role of soluble aluminum in manganese removal via MnOx(s)-coated filtration media in drinking water treatment.

    Science.gov (United States)

    Jones, A; Knocke, W R

    2017-03-15

    The Mn oxide (MnOx(s)) surfaces of water treatment filtration media are known to aid in the capture of dissolved Mn species, but the discovery of significant deposits of Al within these coatings (Tobiason et al., 2008) raised certain questions about the possible role of Al in soluble Mn removal and the formation of the MnOx(s) surface on the media. This phenomenon was addressed by conducting a series of bench-scale column studies that involved the application of solutions containing varying amounts of soluble Al and Mn to MnOx(s)-coated media. The experimental results confirmed that soluble Al was removed in significant amounts by adsorption onto the MnOx(s) media surface. The deposition of soluble Al onto the media surface did not have any significant effect on its ability to remove soluble Mn. Likewise, the relative amounts of Al incorporated into the media coating suggested that uptake of soluble Al alone cannot fully explain the levels of Al often found in real-world, MnOx(s)-coated filter media; instead, the incorporation of particulate forms of Al (routinely found in water treatment plant situations) must contribute to the formation of the MnOx(s) coatings on these media. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Iminium salts and their derivatives as models for catalytic water oxidation

    Science.gov (United States)

    Khatmullin, Renat R.

    The solar energy utilization is one of the most promising strategies for catering the ever-increasing energy demand in a renewable manner. For this reason, several approaches are pursued for solar energy storage, one of which involves the photocatalytic splitting of water. Over recent years, much research has been directed towards the design of transition-metal based water oxidation catalysts to obtain oxygen based on transition metal complexes. The major drawback of most of these catalysts is the cost of transition- metal complexes. For these reasons, the main focus of our research is based on the design of a fully organic catalyst suitable for water oxidation. Our group recently discovered that a flavinium ion performs electrode-mediated electrocatalytic water oxidation at large overpotentials. It was found that catalysis occurs only in the presence of the electrodes that produce active oxides on their surfaces. The mechanism of the catalysis by the flavinium ions was proposed to involve the coupling reaction two oxygen-centered radicals, one of which is derived from to the flavin moiety and the other one is formed at the electrode surface. The electrochemical oxidation of the formed peroxide species then proposed to release the oxygen molecule and recover the catalyst. However, it is important to note, that the detailed study of the mechanism is limited due the fact that electrode participates in the catalytic cycle. For these reasons, it is crucial to develop a fully homogeneous system to study the mechanism of the catalysis. One approach towards a fully molecular catalysis involves a system composed of two- iminium ion moieties joined covalently by a suitable linker. The mechanism of a catalysis is proposed to involve four individual steps: (i) pseudobase formation via a reaction of flavinium ions with water; (ii) proton-coupled oxidation of pseudobases to generate alkoxyl radicals; (iii) coupling of alkoxyl radicals to generate the peroxide intermediate; (iv

  2. Effectiveness of electrolyzed oxidizing water treatment in removing pesticide residues and its effect on produce quality.

    Science.gov (United States)

    Qi, Hang; Huang, Qingguo; Hung, Yen-Con

    2018-01-15

    This study evaluated the effects of electrolyzed oxidizing (EO) water treatment on the removal of pesticide residues (diazinon, cyprodinil and phosmet) from spinach, snap beans and grapes, and the effect on produce quality. High available chlorine content (ACC) and long treatment time of EO water resulted in high pesticide removals. Up to 59.2, 66.5 and 37.1% of diazinon; 43.8, 50.0 and 31.5% of cyprodinil; 85.7, 73.0 and 49.4% of phosmet; were removed from spinach, snap beans and grapes, respectively, after 15min EO water treatment at 120mg/l ACC. EO water was also more effective than electrolyzed reduced water, bleach, VegWash and DI water on pesticide removal. In addition, no significant colour or texture deterioration were found on produce samples treated with EO water. It was concluded, EO water can be very effective in pesticide residue removal from fresh produce without affecting the produce quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Degradation of fluoroquinolone antibiotics by ferrate(VI): Effects of water constituents and oxidized products.

    Science.gov (United States)

    Feng, Mingbao; Wang, Xinghao; Chen, Jing; Qu, Ruijuan; Sui, Yunxia; Cizmas, Leslie; Wang, Zunyao; Sharma, Virender K

    2016-10-15

    The degradation of five fluoroquinolone (FQ) antibiotics (flumequine (FLU), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (OFL) and marbofloxacin (MAR)) by ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) was examined to demonstrate the potential of this iron-based chemical oxidant to treat antibiotics in water. Experiments were conducted at different molar ratios of Fe(VI) to FQs at pH 7.0. All FQs, except FLU, were degraded within 2 min at [Fe(VI)]:[FQ] ≤ 20.0. Multiple additions of Fe(VI) improved the degradation efficiency, and provided greater degradation than a single addition of Fe(VI). The effects of anions, cations, and humic acid (HA), usually present in source waters and wastewaters, on the removal of FLU were investigated. Anions (Cl(-), SO4(2-), NO3(-), and HCO3(-)) and monovalent cations (Na(+) and K(+)) had no influence on the removal of FLU. However, multivalent cations (Ca(2+), Mg(2+), Cu(2+), and Fe(3+)) in water decreased the efficiency of FLU removal by Fe(VI). An increase in the ionic strength of the solution, and the presence of HA in the water, also decreased the percentage of FLU removed by Fe(VI). Experiments on the removal of selected FQs, present as co-existing antibiotics in pure water, river water, synthetic water and wastewater, were also conducted to demonstrate the practical application of Fe(VI) to remove the antibiotics during water treatment. The seventeen oxidized products (OPs) of FLU were identified using solid phase extraction-liquid chromatography-high-resolution mass spectrometry. The reaction pathways are proposed, and are theoretically confirmed by molecular orbital calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Distribution of manganese species in an oxidative dimerization reaction of a bis-terpyridine mononuclear manganese (II) complex and their heterogeneous water oxidation activities.

    Science.gov (United States)

    Takahashi, Kosuke; Sato, Taisei; Yamazaki, Hirosato; Yagi, Masayuki

    2015-11-01

    Heterogeneous water oxidation catalyses were studied as a synthetic model of oxygen evolving complex (OEC) in photosynthesis using mica adsorbing various manganese species. Distribution of manganese species formed in the oxidative dimerization reaction of [Mn(II)(terpy)2](2+) (terpy=2,2':6',2″-terpyridine) (1') with various oxidants in water was revealed. 1' was stoichiometrically oxidized to form di-μ-oxo dinuclear manganese complex, [(OH2)(terpy)Mn(III)(μ-O)2Mn(IV)(terpy)(OH2)](3+) (1) by KMnO4 as an oxidant. When Oxone and Ce(IV) oxidants were used, the further oxidation of 1 to [(OH2)(terpy)Mn(IV)(μ-O)2Mn(IV)(terpy)(OH2)](4+) (2) was observed after the oxidative dimerization reaction of 1'. The mica adsorbates with various composition of 1', 1 and 2 were prepared by adding mica suspension to the various oxidant-treated solutions followed by filtration. The heterogeneous water oxidation catalysis by the mica adsorbates was examined using a Ce(IV) oxidant. The observed catalytic activity of the mica adsorbates corresponded to a content of 1 (1ads) adsorbed on mica for KMnO4- and Oxone-treated systems, indicating that 1' (1'ads) and 2 (2ads) adsorbed on mica do not work for the catalysis. The kinetic analysis suggested that 1ads works for the catalysis through cooperation with adjacent 1ads or 2ads, meaning that 2ads assists the cooperative catalysis by 1ads though 2ads is not able to work for the catalysis alone. For the Ce(IV)-treated system, O2 evolution was hardly observed although the sufficient amount of 1ads was contained in the mica adsorbates. This was explained by the impeded penetration of Ce(IV) ions (as an oxidant for water oxidation) into mica by Ce(3+) cations (generated in oxidative dimerization of 1') co-adsorbed with 1ads. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Supercritical water oxidation of Quinazoline: Effects of conversion parameters and reaction mechanism.

    Science.gov (United States)

    Gong, Yanmeng; Guo, Yang; Wang, Shuzhong; Song, Wenhan

    2016-09-01

    The supercritical water oxidation reaction of quinazoline and a set of related reaction products were investigated in batch reactors by varying the temperature (T, 400-600 °C), time (t, 0-400 s), water density (ρ, 70.79-166.28  kg m(-3)) and oxidation coefficient (OC, 0-4.0). The TOC removal efficiency (CRE) increased significantly as the OC increased, whereas this effect was very limited at high OC (>2.0). Lack of oxygen resulted in low CRE and TN removal efficiency (NRE), also cause coke-formation, and giving high yield of NH3 and nitrogenous organic intermediates. Prolonging reaction time did not provide an appreciable improvement on CRE but remarkably increased NRE at temperature higher than 500 °C. Pyrimidines and pyridines as the nitrogenous intermediates were largely found in GC-MS spectrum. Polymerization among benzene, phenyl radical and benzyl radical played important roles in the formation of PAHs, such as naphthalene, biphenyl, phenanthrene. These collective results showed how the yield of intermediate products responded to changes in the process variables, which permitted the development of a potential reaction network for supercritical water oxidation of quinazoline. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Supercritical Water Oxidation: A Solution for the Elimination of Back-End Organic Reprocessing Wastes

    Energy Technology Data Exchange (ETDEWEB)

    Leybros, A.; Roubaud, A.; Turc, H.A.; Fournel, B. [Supercritical fluids and membranes Laboratory, CEA Valrho, BP 17171, 30207 Bagnols/Ceze Cedex (France)

    2008-07-01

    Supercritical water oxidation (SCWO) is a very efficient technique for total elimination of organic wastes from reprocessing activities on the way of 'zero wastes' facilities. This technology uses the properties of supercritical water (P > 221 bars and T > 647 K) to obtain a good mixing between oxygen (the oxidant) and the organic waste. Thereby, the oxidation reaction is fast and complete. Using the SCWO process, contamination contained in organic materials like spent solvents can be confined in a closed space, like a reactor in a glovebox. A new application is tested for the treatment of solid organic wastes like ion exchange resins (IER). Experiments are made with suspensions of IER in water and isopropyl-alcohol. A nuclear version of the process with the double shell reactor has been constructed and is being tested. The aim of this work is to obtain a treatment capacity of 1 kg/h for the nuclear version with the same global set-up, concept of process and security as well as contamination management as for a 200 g/h pilot. (authors)

  7. Foot of the Wave Analysis for Mechanistic Elucidation and Benchmarking Applications in Molecular Water Oxidation Catalysis.

    Science.gov (United States)

    Matheu, Roc; Neudeck, Sven; Meyer, Franc; Sala, Xavier; Llobet, Antoni

    2016-12-08

    The description of the foot of the wave analysis (FOWA) applied to the electrocatalytic oxidation of water to dioxygen is reported for cases where the rate determining step is first order and second order with regard to catalyst concentration, coinciding mechanistically with the so-called water nucleophilic attack (WNA) and the interaction of two M-O units (I2M, where M represents the metal center of the catalyst), respectively. The newly adapted equations are applied to a range of relevant molecular catalysts, both in homogeneous and heterogeneous phase, and the kinetic parameters are determined, including apparent rate constants and turnover frequencies. In this respect, the application of FOWA at different catalyst concentrations allows elucidation of the reaction mechanism that operates in each case. In addition, catalytic Tafel plots are used for assessing the performance of several molecular water oxidation catalysts (WOCs) as a function of overpotential under analogous conditions, and thus can be used for benchmarking purposes. This analysis was carried out earlier for oxide-based WOCs; however, this is the first report using molecular WOCs. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Efficient Photoelectrochemical Water Oxidation by Metal-Doped Bismuth Vanadate Photoanode with Iron Oxyhydroxide Electrocatalyst

    Directory of Open Access Journals (Sweden)

    Eun Jin Joo

    2016-01-01

    Full Text Available Intensive attention has been currently focused on the discovery of semiconductor and proficient cocatalysts for eventual applications to the photoelectrochemical water splitting system. A W-Mo-doped BiVO4 semiconductor was prepared by the surfactant-assisted thermal decomposition method on a fluorine-doped tin oxide conductive film. The W-Mo-doped BiVO4 films showed a porous morphology with the grain sizes of about 270 nm. Because the hole diffusion length of BiVO4 is about 100 nm, the W-Mo-doped BiVO4 film in this study is an ideal candidate for the photoelectrochemical water oxidation. Iron oxyhydroxide (FeOOH electrocatalyst was chemically deposited on the W-Mo-doped BiVO4 to investigate the effect of the electrocatalyst on the semiconductor. The W-Mo-doped BiVO4/FeOOH composite electrode showed enhanced activity compared to the pristine W-Mo-doped BiVO4 electrode for water oxidation reaction. The chemical deposition is a promising method for the deposition of FeOOH on semiconductor.

  9. Oxidation of chlorfenvinphos in ultrapure and natural