WorldWideScience

Sample records for removing sulfur oxides

  1. Simultaneous removal of nitrogen oxides and sulfur oxides from combustion gases

    Science.gov (United States)

    Clay, David T.; Lynn, Scott

    1976-10-19

    A process for the simultaneous removal of sulfur oxides and nitrogen oxides from power plant stack gases comprising contacting the stack gases with a supported iron oxide catalyst/absorbent in the presence of sufficient reducing agent selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof, to provide a net reducing atmosphere in the SO.sub.x /NO.sub.x removal zone. The sulfur oxides are removed by absorption substantially as iron sulfide, and nitrogen oxides are removed by catalytic reduction to nitrogen and ammonia. The spent iron oxide catalyst/absorbent is regenerated by oxidation and is recycled to the contacting zone. Sulfur dioxide is also produced during regeneration and can be utilized in the production of sulfuric acid and/or sulfur.

  2. Process for removal of sulfur oxides from hot gases

    International Nuclear Information System (INIS)

    Bauerle, G. L.; Kohl, A. L.

    1984-01-01

    A process for the removal of sulfur oxides from two gas streams containing the same. One gas stream is introduced into a spray dryer zone and contacted with a finely dispersed spray of an aqueous medium containing an absorbent for sulfur oxides. The aqueous medium is introduced at a controlled rate so as to provide water to the gas in an amount to produce a cooled product gas having a temperature at least 7 0 C. above its adiabatic saturation temperature and from about 125-300% of the stoichiometric amount of absorbent required to react with the sulfur oxides to be removed from the gas stream. The effluent from the spray dryer zone comprises a gas stream of reduced sulfur oxide content and contains entrained dry particulate reaction products including unreacted absorbent. This gas stream is then introduced into a particulate removal zone from which is withdrawn a gas stream substantially free of particles and having a reduced sulfur oxide content. the dry particulate reaction products are collected and utilized as a source of absorbent for a second aqueous scrubbing medium containing unreacted absorbent for the sulfur oxides. An effluent gas stream is withdrawn from the aqueous scrubbing zone and comprises a water-saturated gas stream of reduced sulfur oxide content and substantially free of particles. The effluent gas streams from the particulate removal zone and the aqueous scrubbing zone are combined in such proportions that the combined gas stream has a temperature above its adiabatic saturation temperature

  3. Method of removing oxides of sulfur and oxides of nitrogen from exhaust gases

    Science.gov (United States)

    Walker, Richard J.

    1986-01-01

    A continuous method is presented for removing both oxides of sulfur and oxides of nitrogen from combustion or exhaust gases with the regeneration of the absorbent. Exhaust gas is cleaned of particulates and HCl by a water scrub prior to contact with a liquid absorbent that includes an aqueous solution of bisulfite and sulfite ions along with a metal chelate, such as, an iron or zinc aminopolycarboxylic acid. Following contact with the combustion gases the spent absorbent is subjected to electrodialysis to transfer bisulfite ions into a sulfuric acid solution while splitting water with hydroxide and hydrogen ion migration to equalize electrical charge. The electrodialysis stack includes alternate layers of anion selective and bipolar membranes. Oxides of nitrogen are removed from the liquid absorbent by air stripping at an elevated temperature and the regenerated liquid absorbent is returned to contact with exhaust gases for removal of sulfur oxides and nitrogen oxides.

  4. Process for the removal of sulfur oxides and nitrogen oxides from flue gas

    International Nuclear Information System (INIS)

    Elshout, R.V.

    1992-01-01

    This patent describes a continuous process for removing sulfur oxide and nitrogen oxide contaminants from the flue gas generated by industrial power plants and boiler systems burning sulfur containing fossil fuels and for converting these contaminants, respectively, into recovered elemental liquid sulfur and nitrogen ammonia and mixtures thereof. It comprises removing at least a portion of the flue gas generated by a power plant or boiler system upstream of the stack thereof; passing the cooled and scrubbed flue gas through an adsorption system; combining a first portion of the reducing gas stream leaving the adsorbers of the adsorption system during regeneration thereof and containing sulfur oxide and nitrogen oxide contaminants with a hydrogen sulfide rich gas stream at a temperature of about 400 degrees F to about 600 degrees F and passing the combined gas streams through a Claus reactor-condenser system over a catalyst in the reactor section thereof which is suitable for promoting the equilibrium reaction between the hydrogen sulfide and the sulfur dioxide of the combined streams to form elemental sulfur

  5. Ultrasound-assisted oxidative process for sulfur removal from petroleum product feedstock.

    Science.gov (United States)

    Mello, Paola de A; Duarte, Fábio A; Nunes, Matheus A G; Alencar, Mauricio S; Moreira, Elizabeth M; Korn, Mauro; Dressler, Valderi L; Flores, Erico M M

    2009-08-01

    A procedure using ultrasonic irradiation is proposed for sulfur removal of a petroleum product feedstock. The procedure involves the combination of a peroxyacid and ultrasound-assisted treatment in order to comply with the required sulfur content recommended by the current regulations for fuels. The ultrasound-assisted oxidative desulfurization (UAOD) process was applied to a petroleum product feedstock using dibenzothiophene as a model sulfur compound. The influence of ultrasonic irradiation time, oxidizing reagents amount, kind of solvent for the extraction step and kind of organic acid were investigated. The use of ultrasonic irradiation allowed higher efficiency for sulfur removal in comparison to experiments performed without its application, under the same reactional conditions. Using the optimized conditions for UAOD, the sulfur removal was about 95% after 9min of ultrasonic irradiation (20kHz, 750W, run at 40%), using hydrogen peroxide and acetic acid, followed by extraction with methanol.

  6. Removal and recovery of nitrogen and sulfur oxides from gaseous mixtures containing them

    International Nuclear Information System (INIS)

    Cooper, H.B.H.

    1984-01-01

    A cyclic process for removing lower valence nitrogen oxides from gaseous mixtures includes treating the mixtures with an aqueous media including alkali metal carbonate and alkali metal bicarbonate and a preoxygen oxidant to form higher valence nitrogen oxides and to capture these oxides as alkali metal salts, expecially nitrites and nitrates, in a carbonate/bicarbonate-containing product aqueous media. Highly selective recovery of nitrates in high purity and yield may then follow, as by crystallization, with the carbonate and bicarbonate alkali metal salts strongly increasing the selectivity and yield of nitrates. The product nitrites are converted to nitrates by oxidation after lowering the product aqueous media pH to below about 9. A cyclic process for removing sulfur oxides from gas mixtures includes treating these mixtures includes treating these mixtures with aqueous media including alkali metal carbonate and alkali metal bicarbonate where the ratio of alkali metal to sulfur dioxide is not less than 2. The sulfur values may be recovered from the resulting carbonate/bicarbonate/-sulfite containing product aqueous media as alkali metal sulfate or sulfite salts which are removed by crystallization from the carbonate-containing product aqueous media. As with the nitrates, the carbonate/bicarbonate system strongly increases yield of sulfate or sulfite during crystallization. Where the gas mixtures include both sulfur dioxide and lower valence nitrogen oxides, the processes for removing lower valence nitrogen oxides and sulfur dioxide may be combined into a single removal/recovery system, or may be effected in sequence

  7. Method of removing and recovering elemental sulfur from highly reducing gas streams containing sulfur gases

    Science.gov (United States)

    Gangwal, Santosh K.; Nikolopoulos, Apostolos A.; Dorchak, Thomas P.; Dorchak, Mary Anne

    2005-11-08

    A method is provided for removal of sulfur gases and recovery of elemental sulfur from sulfur gas containing supply streams, such as syngas or coal gas, by contacting the supply stream with a catalyst, that is either an activated carbon or an oxide based catalyst, and an oxidant, such as sulfur dioxide, in a reaction medium such as molten sulfur, to convert the sulfur gases in the supply stream to elemental sulfur, and recovering the elemental sulfur by separation from the reaction medium.

  8. Microbial Desulfurization of a Crude Oil Middle-Distillate Fraction: Analysis of the Extent of Sulfur Removal and the Effect of Removal on Remaining Sulfur

    Science.gov (United States)

    Grossman, M. J.; Lee, M. K.; Prince, R. C.; Garrett, K. K.; George, G. N.; Pickering, I. J.

    1999-01-01

    Rhodococcus sp. strain ECRD-1 was evaluated for its ability to desulfurize a 232 to 343°C middle-distillate (diesel range) fraction of Oregon basin (OB) crude oil. OB oil was provided as the sole source of sulfur in batch cultures, and the extent of desulfurization and the chemical fate of the residual sulfur in the oil after treatment were determined. Gas chromatography (GC), flame ionization detection, and GC sulfur chemiluminesce detection analysis were used to qualitatively evaluate the effect of Rhodococcus sp. strain ECRD-1 treatment on the hydrocarbon and sulfur content of the oil, respectively. Total sulfur was determined by combustion of samples and measurement of released sulfur dioxide by infrared absorption. Up to 30% of the total sulfur in the middle distillate cut was removed, and compounds across the entire boiling range of the oil were affected. Sulfur K-edge X-ray absorption-edge spectroscopy was used to examine the chemical state of the sulfur remaining in the treated OB oil. Approximately equal amounts of thiophenic and sulfidic sulfur compounds were removed by ECRD-1 treatment, and over 50% of the sulfur remaining after treatment was in an oxidized form. The presence of partially oxidized sulfur compounds indicates that these compounds were en route to desulfurization. Overall, more than two-thirds of the sulfur had been removed or oxidized by the microbial treatment. PMID:9872778

  9. Removal of Sulfur from CaF2 Containing Desulfurization Slag Exhausted from Secondary Steelmaking Process by Oxidation

    Science.gov (United States)

    Hiraki, Takehito; Kobayashi, Junichi; Urushibata, Satomi; Matsubae, Kazuyo; Nagasaka, Tetsuya

    2012-08-01

    The oxidation behavior of sulfur in desulfurization slag generated from the secondary steelmaking process with air has been investigated in the temperature range of 973 K to 1373 K (700 °C to 1100 °C). Although a high removal rate of sulfur is not achieved at temperatures lower than 1273 K (1000 °C) because of the formation of CaSO4, most of the sulfur is rapidly removed from slag as SO2 gas in the 1273 K to 1373 K (700 °C to 1100 °C) range. This finding indicates that the desulfurization slag generated from the secondary steelmaking process can be reused as a desulfurized flux through air oxidation, making it possible to reduce significantly the amount of desulfurization slag for disposal.

  10. Radiation induced sulfur dioxide removal

    International Nuclear Information System (INIS)

    Chmielewski, A.G.

    2000-01-01

    The biggest source of air pollution is the combustion of fossil fuels, were pollutants such as particulate, sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), and volatile organic compounds (VOC) are emitted. Among these pollutants, sulfur dioxide plays the main role in acidification of the environment. The mechanism of sulfur dioxide transformation in the environment is partly photochemical. This is not direct photooxidation, however, but oxidation through formed radicals. Heterogenic reactions play an important role in this transformation as well; therefore, observations from environmental chemistry can be used in air pollution control engineering. One of the most promising technologies for desulfurization of the flue gases (and simultaneous denitrification) is radiation technology with an electron accelerator application. Contrary to the nitrogen oxides (NO x ) removal processes, which is based on pure radiation induced reactions, sulfur dioxide removal depends on two pathways: a thermochemical reaction in the presence of ammonia/water vapor and a radiation set of radiochemical reactions. The mechanism of these reactions and the consequent technological parameters of the process are discussed in this paper. The industrial application of this radiation technology is being implemented in an industrial pilot plant operated by INCT at EPS Kaweczyn. A full-scale industrial plant is currently in operation in China, and two others are under development in Japan and Poland. (author)

  11. Effect of sulfur removal on scale adhesion to PWA 1480

    International Nuclear Information System (INIS)

    Smialek, J.L.; Tubbs, B.K.

    1995-01-01

    A commercial superalloy, PWA 1480, was annealed in hydrogen at 1,000 C to 1,300 C in order to remove a 10 ppmw sulfur impurity. This treatment was very successful above 1,200 C, resulting in residual sulfur contents below 0.1 ppmw. The degree of scale adhesion in subsequent 1,100 C cyclic oxidation tests was inversely related to residual sulfur content. Control of adhesion by desulfurization in the absence of reactive elements supports an adhesion mechanism based on oxide-metal bonding weakened by sulfur segregation. Attempts at sulfur purging and improving adhesion by repeated oxidation/polishing were not successful, in contrast to previous studies on NiCrAl

  12. Effect of sulfur removal on Al2O3 scale adhesion

    Science.gov (United States)

    Smialek, James L.

    1991-03-01

    If the role of reactive element dopants in producing A12O3 scale adhesion on NiCrAl alloys is to getter sulfur and prevent interfacial segregation, then eliminating sulfur from undoped alloys should also produce adherence. Four experiments successfully produced scale adhesion by sulfur removal alone. (1) Repeated oxidation and polishing of a pure NiCrAl alloy lowered the sulfur content from 10 to 2 parts per million by weight (ppmw), presumably by removing the segregated interfacial layer after each cycle. Total scale spallation changed to total retention after 13 such cycles, with no changes in the scale or interfacial morphology. (2) Thinner samples became adherent after fewer oxidation polishing cycles because of a more limited supply of sulfur. (3) Spalling in subsequent cyclic oxidation tests of samples from experiment (1) was a direct function of the initial sulfur content. (4) Desulfurization to 0.1 ppmw levels was accomplished by annealing melt-spun foil in 1 arm H2. These foils produced oxidation weight change curves for 500 1-hour cycles at 1100 °C similar to those for Y- or Zr-doped NiCrAl. The transition between adherent and nonadherent behavior was modeled in terms of sulfur flux, sulfur content, and sulfur segregation.

  13. Extractive de-sulfurization and de-ashing of high sulfur coals by oxidation with ionic liquids

    International Nuclear Information System (INIS)

    Saikia, Binoy K.; Khound, Kakoli; Baruah, Bimala P.

    2014-01-01

    Highlights: • Extractive de-sulfurization and de-ashing process for cleaning high sulfur coals. • The process removes inorganic as well as organic sulfur components from high sulfur coals. • The process has less risk to chemists and other surroundings. - Abstract: The environmental consequences of energy production from coals are well known, and are driving the development of desulfurization technologies. In this investigation, ionic liquids were examined for extractive desulfurization and de-ashing in industrially important high sulfur sub-bituminous Indian coals. The ionic liquids, namely, 1-n-butyl-3-methylimidazolium tetrafluoroborate (IL1) and 1-n-butyl 3-methylimidazolium chloride (IL2) were employed for desulfurization of a few Indian coal samples in presence of HCOOH/H 2 O 2 and V 2 O 5 . Results show the maximum removal of 50.20% of the total sulfur, 48.00% of the organic sulfur, and 70.37 wt% of the ash in this process. The ionic liquids were recovered and subsequently used for further desulfurization. FT-IR spectra reveal the transformation of organic sulfur functionalities into the sulfoxides (S=O) and sulfones (-SO 2 ) due to the oxidative reactions. The sulfate, pyrite and sulfides (aryls) signals in the near edge X-ray absorption fine structure (NEXAFS) of the oxidized coal samples showed sulfur transformation during the desulfurization process. The study demonstrates the removal of significant amount of inorganic as well as organic sulfur (aryls) components from the original high sulfur coal samples to make them cleaner

  14. Catalytic removal of sulfur dioxide from dibenzothiophene sulfone over Mg-Al mixed oxides supported on mesoporous silica.

    Science.gov (United States)

    You, Nansuk; Kim, Min Ji; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Jeon, Jong-Ki

    2010-05-01

    Dibenzothiophene sulfone (DBTS), one of the products of the oxidative desulfurization of heavy oil, can be removed through extraction as well as by an adsorption process. It is necessary to utilize DBTS in conjunction with catalytic cracking. An object of the present study is to provide an Mg-Al-mesoporous silica catalyst for the removal of sulfur dioxide from DBTS. The characteristics of the Mg-Al-mesoporous silica catalyst were investigated through N2 adsorption, XRD, ICP, and XRF. An Mg-Al-mesoporous silica catalyst formulated in a direct incorporation method showed higher catalytic performance compared to pure MgO during the catalytic removal of sulfur dioxide from DBTS. The higher dispersion of Mg as well as the large surface area of the Mg-Al-mesoporous silica catalyst strongly influenced the catalyst basicity in DBTS cracking.

  15. Modeling of a Large-Scale High Temperature Regenerative Sulfur Removal Process

    DEFF Research Database (Denmark)

    Konttinen, Jukka T.; Johnsson, Jan Erik

    1999-01-01

    model that does not account for bed hydrodynamics. The pilot-scale test run results, obtained in the test runs of the sulfur removal process with real coal gasifier gas, have been used for parameter estimation. The validity of the reactor model for commercial-scale design applications is discussed.......Regenerable mixed metal oxide sorbents are prime candidates for the removal of hydrogen sulfide from hot gasifier gas in the simplified integrated gasification combined cycle (IGCC) process. As part of the regenerative sulfur removal process development, reactor models are needed for scale......-up. Steady-state kinetic reactor models are needed for reactor sizing, and dynamic models can be used for process control design and operator training. The regenerative sulfur removal process to be studied in this paper consists of two side-by-side fluidized bed reactors operating at temperatures of 400...

  16. Sulfur Removal by Adding Iron During the Digestion Process of High-sulfur Bauxite

    Science.gov (United States)

    Zhanwei, Liu; Hengwei, Yan; Wenhui, Ma; Keqiang, Xie; Dunyong, Li; Licong, Zheng; Pengfei, Li

    2018-04-01

    This paper proposes a novel approach to sulfur removal by adding iron during the digestion process. Iron can react with high-valence sulfur (S2O3 2-, SO3 2-, SO4 2-) to generate S2- at digestion temperature, and then S2- enter red mud in the form of Na3FeS3 to be removed. As iron dosage increases, high-valence sulfur concentration decreases, but the concentration of S2- increases; sulfur digestion rate decreases while sulfur content in red mud markedly increases; the alumina digestion rate, conversely, remains fairly stable. So sulfur can be removed completely by adding iron in digestion process, which provide a theoretical basis for the effective removal of sulfur in alumina production process.

  17. Removal of sulfur and nitrogen containing pollutants from discharge gases

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, James I. (Pittsburgh, PA)

    1986-01-01

    Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

  18. Removal of sulfur and nitrogen containing pollutants from discharge gases

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, J.I.

    1985-02-08

    Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

  19. Conversion of sulfur and nitrogen oxides in air under exposure to microsecond electron beams

    International Nuclear Information System (INIS)

    Denisov, G.V.; Kuznetsov, D.L.; Novoselov, Yu.N.; Tkachenko, R.M.

    2002-01-01

    Flue gases of power plants realizing sulfur and nitrogen oxides into the atmosphere represent one of the environmental pollution sources. Paper presents the results of experimental investigations of conversion of sulfur and nitrogen oxides in the ionized gas mixture simulating composition of off-gases of thermal power stations. Pulse beam of microsecond duration electrons was used as a source of ionization. Mutual influence of both types of oxides on process of their conversion is shown. One studied possible kinetic mechanisms to remove sulfur and nitrogen oxides from gaseous mixture [ru

  20. A dynamic mathematical model for microbial removal of pyritic sulfur from coal.

    Science.gov (United States)

    Kargi, F; Weissman, J G

    1984-06-01

    A dynamic mathematical model has been developed to describe microbial desulfurization of coal by Thiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption-description constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm(3) mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leaching.

  1. Simultaneous removal of nitrogen oxide/nitrogen dioxide/sulfur dioxide from gas streams by combined plasma scrubbing technology.

    Science.gov (United States)

    Chang, Moo Been; Lee, How Ming; Wu, Feeling; Lai, Chi Ren

    2004-08-01

    Oxides of nitrogen (NOx) [nitrogen oxide (NO) + nitrogen dioxide (NO2)] and sulfur dioxide (SO2) are removed individually in traditional air pollution control technologies. This study proposes a combined plasma scrubbing (CPS) system for simultaneous removal of SO2 and NOx. CPS consists of a dielectric barrier discharge (DBD) and wet scrubbing in series. DBD is used to generate nonthermal plasmas for converting NO to NO2. The water-soluble NO2 then can be removed by wet scrubbing accompanied with SO2 removal. In this work, CPS was tested with simulated exhausts in the laboratory and with diesel-generator exhausts in the field. Experimental results indicate that DBD is very efficient in converting NO to NO2. More than 90% removal of NO, NOx, and SO2 can be simultaneously achieved with CPS. Both sodium sulfide (Na2S) and sodium sulfite (Na2SO3) scrubbing solutions are good for NO2 and SO2 absorption. Energy efficiencies for NOx and SO2 removal are 17 and 18 g/kWh, respectively. The technical feasibility of CPS for simultaneous removal of NO, NO2, and SO2 from gas streams is successfully demonstrated in this study. However, production of carbon monoxide as a side-product (approximately 100 ppm) is found and should be considered.

  2. Biotransformation and removal of sulfur from dibenzothiophene using improved bio catalytic methods

    International Nuclear Information System (INIS)

    La Rotta, C. E; Mora, A.L; Madero, A; Mogollon, L.I

    1998-01-01

    Three methods for the removal of sulfur from dibenzothiophene were evaluated using bio catalytic processes. The methods were a microbial, an enzymatic and a combined one that involves a previous enzymatic oxidation followed by microbial degradation. The bioconversion was evaluated over the molecular dibenzothiophene model, obtaining higher bioconversion percentages through the combined method. The microorganisms used in this study correspond to several Colombian indigenous strains isolated by direct methods from natural sources, and using a standard strain as positive control. All strains have shown sulfur removal capacity, and organic solvent tolerance. The enzyme used was a hemo protein with peroxidase activity, Cytochrome C, obtained from equine heart

  3. Synthesis and Application of Iron Oxide/Silica Gel Nanocomposite for Removal of Sulfur Dyes from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Naser Tavassoli

    2017-03-01

    Full Text Available Background & Aims of the Study: water pollution by synthetic organic dyes is mainly regarded as environmental and ecological critical issues worldwide. In this research, magnetite iron oxide/silica gel nanocomposite (termed as Fe3O4/SG was synthesized chemically and then used as an effective adsorbent for removal of sulfur dyes from aqueous solution. Materials and Methods: The various parameters such as pH, sorbent dosage, initial dye concentration, contact time and dye solution temperature were investigated in a batch system. The equilibrium data were analyzed by Langmuir and Freundlich isotherm models. Results: The experimental data fit well with pseudo-second-order kinetic model (R2≥0.998 and conformed better to Langmuir isotherm model (R2≥0.997. The maximum adsorption capacity for Fe3O4/SG obtained from the Langmuir model was 11.1mg/g. Evaluation of thermodynamic parameters proved that the adsorption process was normally feasible, spontaneous and exothermic. Conclusion: It can be concluded that the Fe3O4/SG can be considered as a cost-effective and an environmental friendly adsorbent for efficient removal of sulfur dyes from aqueous solutions.

  4. Reduction of produced elementary sulfur in denitrifying sulfide removal process.

    Science.gov (United States)

    Zhou, Xu; Liu, Lihong; Chen, Chuan; Ren, Nanqi; Wang, Aijie; Lee, Duu-Jong

    2011-05-01

    Denitrifying sulfide removal (DSR) processes simultaneously convert sulfide, nitrate, and chemical oxygen demand from industrial wastewater into elemental sulfur, dinitrogen gas, and carbon dioxide, respectively. The failure of a DSR process is signaled by high concentrations of sulfide in reactor effluent. Conventionally, DSR reactor failure is blamed for overcompetition for heterotroph to autotroph communities. This study indicates that the elementary sulfur produced by oxidizing sulfide that is a recoverable resource from sulfide-laden wastewaters can be reduced back to sulfide by sulfur-reducing Methanobacterium sp. The Methanobacterium sp. was stimulated with excess organic carbon (acetate) when nitrite was completely consumed by heterotrophic denitrifiers. Adjusting hydraulic retention time of a DSR reactor when nitrite is completely consumed provides an additional control variable for maximizing DSR performance.

  5. Air Quality Criteria for Sulfur Oxides.

    Science.gov (United States)

    National Air Pollution Control Administration (DHEW), Washington, DC.

    Included is a literature review which comprehensively discusses knowledge of the sulfur oxides commonly found in the atmosphere. The subject content is represented by the 10 chapter titles: Physical and Chemical Properties and the Atmospheric Reactions of the Oxides of Sulfur; Sources and Methods of Measurements of Sulfur Oxides in the Atmosphere;…

  6. Removal of sulfur compounds from diesel using ArF laser and oxygen.

    Science.gov (United States)

    Gondal, M A; Siddiqui, M N; Al-Hooshani, K

    2013-01-01

    A laser-based technique for deep desulfurization of diesel and other hydrocarbon fuels by removal of dimethyldibenzothiophene (DMDBT), a persistent sulfur contaminant in fuel oils has been developed. We report a selective laser excitation of DMDBT in diesel and model compounds such as n-hexane in a reaction chamber under oxygen environment where oxidative reactions can take place. ArF laser emitting at 193 nm was employed for excitation of oxygen and DMDBT, while for process optimization, the laser energy was varied from 50 to 200 mJ/cm(2). The laser-irradiated DMDBT solution under continuous oxygen flow was analyzed by UV absorption spectrometer to determine the photochemical oxidative degradation of DMDBT. In just 5 min of laser irradiation time, almost 95% DMDBT was depleted in a diesel containing 200 ppm of DMDBT. This article provides a new method for the removal of sulfur compounds from diesel by laser based photochemical process.

  7. Anaerobic sulfide-oxidation in marine colorless sulfur-oxidizing bacteria

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

    Colorless sulfur-oxidizing bacteria are ubiquitous in Indian waters and have the ability to oxidize sulfide under anaerobic conditions. These bacteria can not only mediate the sulfur cycle oxidatively but also the nitrogen cycle reductively without...

  8. KINETICS OF DIRECT OXIDATION OF H2S IN COAL GAS TO ELEMENTAL SULFUR; F

    International Nuclear Information System (INIS)

    K.C. Kwon

    2002-01-01

    Removal of hydrogen sulfide (H(sub 2)S) from coal gasifier gas and sulfur recovery are key steps in the development of Department of Energy's (DOE's) advanced Vision 21 plants that employ coal and natural gas and produce electric power and clean transportation fuels. These Vision 21 plants will require highly clean coal gas with H(sub 2)S below 1 ppm and negligible amounts of trace contaminants such as hydrogen chloride, ammonia, alkali, heavy metals, and particulate. The conventional method of sulfur removal and recovery employing amine, Claus, and tail-gas treatment is very expensive. A second generation approach developed under DOE's sponsorship employs hot-gas desulfurization (HGD) using regenerable metal oxide sorbents followed by Direct Sulfur Recovery Process (DSRP). However, this process sequence does not remove trace contaminants and is targeted primarily towards the development of advanced integrated gasification combined cycle (IGCC) plants that produce electricity (not both electricity and transportation fuels). There is an immediate as well as long-term need for the development of cleanup processes that produce highly clean coal gas for next generation Vision 21 plants. To this end, a novel process is now under development at Research Triangle Institute (RTI) in which the H(sub 2)S in coal gas is directly oxidized to elemental sulfur over a selective catalyst. Such a process is ideally suited for coal gas from commercial gasifiers with a quench system to remove essentially all the trace contaminants except H(sub 2)S. This direct oxidation process has the potential to produce a super clean coal gas more economically than both conventional amine-based processes and HGD/DSRP. The objective of this research is to support the near- and long-term DOE efforts to commercialize this direct oxidation technology. Specifically, we aim to: Measure the kinetics of direct oxidation of H(sub 2)S to elemental sulfur over selective catalysts in the presence of major

  9. Influence of sulfurous oxide on plants

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, J

    1872-01-01

    It has been determined that of the trees living in an atmosphere containing sulfurous oxide, the conifers suffer more injuries than ordinary foliaged trees. Experiments were conducted to find the causes of injuries and their relation in these two kinds of plants. Pine and alder were chosen as test plants. It was found that 1000 square centimeters of pine leaves had absorbed 1.6 c.c. of sulfurous oxide and the same surface area of alder leaves had accumulated 7.9 c.c. of sulfurous oxide. Experiments were also conducted to determine the effects of sulfurous oxide on transpiration in plants. Two similar twigs of a sycamore were arranged so that the water transpired could be weighed. Results indicate that the ratio between the total amount of water transpired by the leaves not acted on by the sulfurous oxide and those under its influence was 3.8:1. The author concludes that the amount of sulfurous oxide absorbed by pine leaves is smaller than that absorbed by trees with ordinary foliage for equal surfaces. Since its effect on transpiration is less in the case of pine, the cause of the greater injury to pine trees in nature must be due to the accumulation of sulfur. In trees annual leaves the damage to one year's foliage would have only an indirect influence on that of the following year.

  10. Graphene oxide as a sulfur immobilizer in high performance lithium/sulfur cells

    Science.gov (United States)

    Zhang, Yuegang; Cairns, Elton J.; Ji, Liwen; Rao, Mumin

    2017-06-06

    The loss of sulfur cathode material as a result of polysulfide dissolution causes significant capacity fading in rechargeable lithium/sulfur cells. Embodiments of the invention use a chemical approach to immobilize sulfur and lithium polysulfides via the reactive functional groups on graphene oxide. This approach obtains a uniform and thin (.about.tens of nanometers) sulfur coating on graphene oxide sheets by a chemical reaction-deposition strategy and a subsequent low temperature thermal treatment process. Strong interaction between graphene oxide and sulfur or polysulfides demonstrate lithium/sulfur cells with a high reversible capacity of 950-1400 mAh g.sup.-1, and stable cycling for more than 50 deep cycles at 0.1 C.

  11. Graphene oxide as a sulfur immobilizer in high performance lithium/sulfur cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuegang; Cairns, Elton J.; Ji, Liwen; Rao, Mumin

    2017-12-26

    The loss of sulfur cathode material as a result of polysulfide dissolution causes significant capacity fading in rechargeable lithium/sulfur cells. Embodiments of the invention use a chemical approach to immobilize sulfur and lithium polysulfides via the reactive functional groups on graphene oxide. This approach obtains a uniform and thin (.about.tens of nanometers) sulfur coating on graphene oxide sheets by a chemical reaction-deposition strategy and a subsequent low temperature thermal treatment process. Strong interaction between graphene oxide and sulfur or polysulfides demonstrate lithium/sulfur cells with a high reversible capacity of 950-1400 mAh g.sup.-1, and stable cycling for more than 50 deep cycles at 0.1 C.

  12. Oxidation of inorganic sulfur compounds in acidophilic prokaryotes

    Energy Technology Data Exchange (ETDEWEB)

    Rohwerder, T.; Sand, W. [Universitaet Duisburg-Essen, Biofilm Centre, Aquatic Biotechnology, Duisburg (Germany)

    2007-07-15

    The oxidation of reduced inorganic sulfur compounds to sulfuric acid is of great importance for biohydrometallurgical technologies as well as the formation of acidic (below pH 3) and often heavy metal-contaminated environments. The use of elemental sulfur as an electron donor is the predominant energy-yielding process in acidic natural sulfur-rich biotopes but also at mining sites containing sulfidic ores. Contrary to its significant role in the global sulfur cycle and its biotechnological importance, the microbial fundamentals of acidophilic sulfur oxidation are only incompletely understood. Besides giving an overview of sulfur-oxidizing acidophiles, this review describes the so far known enzymatic reactions related to elemental sulfur oxidation in acidophilic bacteria and archaea. Although generally similar reactions are employed in both prokaryotic groups, the stoichiometry of the key enzymes is different. Bacteria oxidize elemental sulfur by a sulfur dioxygenase to sulfite whereas in archaea, a sulfur oxygenase reductase is used forming equal amounts of sulfide and sulfite. In both cases, the activation mechanism of elemental sulfur is not known but highly reactive linear sulfur forms are assumed to be the actual substrate. Inhibition as well as promotion of these biochemical steps is highly relevant in bioleaching operations. An efficient oxidation can prevent the formation of passivating sulfur layers. In other cases, a specific inhibition of sulfur biooxidation may be beneficial for reducing cooling and neutralization costs. In conclusion, the demand for a better knowledge of the biochemistry of sulfur-oxidizing acidophiles is underlined. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  13. Mathematical modeling of simultaneous carbon-nitrogen-sulfur removal from industrial wastewater.

    Science.gov (United States)

    Xu, Xi-Jun; Chen, Chuan; Wang, Ai-Jie; Ni, Bing-Jie; Guo, Wan-Qian; Yuan, Ye; Huang, Cong; Zhou, Xu; Wu, Dong-Hai; Lee, Duu-Jong; Ren, Nan-Qi

    2017-01-05

    A mathematical model of carbon, nitrogen and sulfur removal (C-N-S) from industrial wastewater was constructed considering the interactions of sulfate-reducing bacteria (SRB), sulfide-oxidizing bacteria (SOB), nitrate-reducing bacteria (NRB), facultative bacteria (FB), and methane producing archaea (MPA). For the kinetic network, the bioconversion of C-N by heterotrophic denitrifiers (NO 3 - →NO 2 - →N 2 ), and that of C-S by SRB (SO 4 2- →S 2- ) and SOB (S 2- →S 0 ) was proposed and calibrated based on batch experimental data. The model closely predicted the profiles of nitrate, nitrite, sulfate, sulfide, lactate, acetate, methane and oxygen under both anaerobic and micro-aerobic conditions. The best-fit kinetic parameters had small 95% confidence regions with mean values approximately at the center. The model was further validated using independent data sets generated under different operating conditions. This work was the first successful mathematical modeling of simultaneous C-N-S removal from industrial wastewater and more importantly, the proposed model was proven feasible to simulate other relevant processes, such as sulfate-reducing, sulfide-oxidizing process (SR-SO) and denitrifying sulfide removal (DSR) process. The model developed is expected to enhance our ability to predict the treatment of carbon-nitrogen-sulfur contaminated industrial wastewater. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Biologically removing sulfur from dilute gas flows

    Science.gov (United States)

    Ruitenberg, R.; Dijkman, H.; Buisman, C. J. N.

    1999-05-01

    A biological process has been developed to clean off-gases containing sulfur dioxide from industrial installations. The sulfur dioxide is converted into hydrogen sulfide, which can then be oxidized to elemental sulfur if not used on-site. The process produces no waste products that require disposal and has a low reagent consumption.

  15. Synthesis and characterization of porous metal oxides and desulfurization studies of sulfur containing compounds

    Science.gov (United States)

    Garces Trujillo, Hector Fabian

    This thesis contains two parts: 1) synthesis and characterization of porous metal oxides that include zinc oxide and a porous mixed-valent manganese oxide with an amorphous structure (AMO) 2) the desulfurization studies for the removal of sulfur compounds. Zinc oxide with different nano-scale morphologies may result in various porosities with different adsorption capabilities. A tunable shape microwave synthesis of ZnO nano-spheres in a co-solvent mixture is presented. The ZnO nano-sphere material is investigated as a desulfurizing sorbent in a fixed bed reactor in the temperature range 200 to 400 °C and compared with ZnO nanorods and platelet-like morphologies. Fresh and sulfided materials were characterized by X-ray diffraction (XRD), BET specific surface area, pore volume, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (SEM/EDX), Raman spectroscopy, and thermogravimetric analysis (TGA). The tunable shape microwave synthesis of ZnO presents a high sulfur sorption capacity at temperatures as low as 200 °C which accounts for a three and four fold enhancement over the other preparations presented in this work, and reached 76 % of the theoretical sulfur capacity (TSC) at 300 °C. Another ZnO material with a bimodal micro- and mesopore size distribution investigated as a desulfurizing sorbent presents a sorption capacity that reaches 87% of the theoretical value for desulfurization at 400 °C at breakthrough time. A deactivation model that considers the activity of the solid reactant was used to fit the experimental data. Good agreement between the experimental breakthrough curves and the model predictions are obtained. Manganese oxides are a type of metal oxide materials commonly used in catalytic applications. Little is known about the adsorption capabilities for the removal of sulfur compounds. One of these manganese oxides; amorphous manganese oxide (AMO) is highly promising material for low temperature sorption processes. Amorphous

  16. Halophilic and haloalkaliphilic sulfur-oxidizing bacteria

    NARCIS (Netherlands)

    Sorokin, D.Y.; Banciu, H.; Robertson, L.A.; Kuenen, J.G.; Muntyan, M.S.; Muyzer, G.; Rosenberg, E.; DeLong, F.; Delong, E.; Lory, S.; Stackebrandt, E.; Thompson, F.

    2013-01-01

    Chemotrophic sulfur-oxidizing bacteria (SOB) represent an important functional group of microorganisms responsible for the dark oxidation of reduced sulfur compounds generated by sulfidogens. Until recently, only a single genus of halophilic SOB (Halothiobacillus) has been described, and nothing was

  17. Acidithiobacillus caldus sulfur oxidation model based on transcriptome analysis between the wild type and sulfur oxygenase reductase defective mutant.

    Directory of Open Access Journals (Sweden)

    Linxu Chen

    Full Text Available Acidithiobacillus caldus (A. caldus is widely used in bio-leaching. It gains energy and electrons from oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs for carbon dioxide fixation and growth. Genomic analyses suggest that its sulfur oxidation system involves a truncated sulfur oxidation (Sox system (omitting SoxCD, non-Sox sulfur oxidation system similar to the sulfur oxidation in A. ferrooxidans, and sulfur oxygenase reductase (SOR. The complexity of the sulfur oxidation system of A. caldus generates a big obstacle on the research of its sulfur oxidation mechanism. However, the development of genetic manipulation method for A. caldus in recent years provides powerful tools for constructing genetic mutants to study the sulfur oxidation system.An A. caldus mutant lacking the sulfur oxygenase reductase gene (sor was created and its growth abilities were measured in media using elemental sulfur (S(0 and tetrathionate (K(2S(4O(6 as the substrates, respectively. Then, comparative transcriptome analysis (microarrays and real-time quantitative PCR of the wild type and the Δsor mutant in S(0 and K(2S(4O(6 media were employed to detect the differentially expressed genes involved in sulfur oxidation. SOR was concluded to oxidize the cytoplasmic elemental sulfur, but could not couple the sulfur oxidation with the electron transfer chain or substrate-level phosphorylation. Other elemental sulfur oxidation pathways including sulfur diooxygenase (SDO and heterodisulfide reductase (HDR, the truncated Sox pathway, and the S(4I pathway for hydrolysis of tetrathionate and oxidation of thiosulfate in A. caldus are proposed according to expression patterns of sulfur oxidation genes and growth abilities of the wild type and the mutant in different substrates media.An integrated sulfur oxidation model with various sulfur oxidation pathways of A. caldus is proposed and the features of this model are summarized.

  18. Photoresist removal using gaseous sulfur trioxide cleaning technology

    Science.gov (United States)

    Del Puppo, Helene; Bocian, Paul B.; Waleh, Ahmad

    1999-06-01

    A novel cleaning method for removing photoresists and organic polymers from semiconductor wafers is described. This non-plasma method uses anhydrous sulfur trioxide gas in a two-step process, during which, the substrate is first exposed to SO3 vapor at relatively low temperatures and then is rinsed with de-ionized water. The process is radically different from conventional plasma-ashing methods in that the photoresist is not etched or removed during the exposure to SO3. Rather, the removal of the modified photoresist takes place during the subsequent DI-water rinse step. The SO3 process completely removes photoresist and polymer residues in many post-etch applications. Additional advantages of the process are absence of halogen gases and elimination of the need for other solvents and wet chemicals. The process also enjoys a very low cost of ownership and has minimal environmental impact. The SEM and SIMS surface analysis results are presented to show the effectiveness of gaseous SO3 process after polysilicon, metal an oxide etch applications. The effects of both chlorine- and fluorine-based plasma chemistries on resist removal are described.

  19. Sulfur removal from low-sulfur gasoline and diesel fuel by metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, G.; Haemmerle, M.; Moos, R. [Functional Materials, University of Bayreuth, Bayreuth (Germany); Malkowsky, I.M.; Kiener, C. [BASF SE, Ludwigshafen (Germany); Achmann, S.

    2010-02-15

    Several materials in the class of metal-organic frameworks (MOF) were investigated to determine their sorption characteristics for sulfur compounds from fuels. The materials were tested using different model oils and common fuels such as low-sulfur gasoline or diesel fuel at room temperature and ambient pressure. Thiophene and tetrahydrothiophene (THT) were chosen as model substances. Total-sulfur concentrations in the model oils ranged from 30 mg/kg (S from thiophene) to 9 mg/kg (S from tetrahydrothiophene) as determined by elementary analysis. Initial sulfur contents of 8 mg/kg and 10 mg/kg were identified for low-sulfur gasoline and for diesel fuel, respectively, by analysis of the common liquid fuels. Most of the MOF materials examined were not suitable for use as sulfur adsorbers. However, a high efficiency for sulfur removal from fuels and model oils was noticed for a special copper-containing MOF (copper benzene-1,3,5-tricarboxylate, Cu-BTC-MOF). By use of this material, 78 wt % of the sulfur content was removed from thiophene containing model oils and an even higher decrease of up to 86 wt % was obtained for THT-based model oils. Moreover, the sulfur content of low-sulfur gasoline was reduced to 6.5 mg/kg, which represented a decrease of more than 22 %. The sulfur level in diesel fuel was reduced by an extent of 13 wt %. Time-resolved measurements demonstrated that the sulfur-sorption mainly occurs in the first 60 min after contact with the adsorbent, so that the total time span of the desulfurization process can be limited to 1 h. Therefore, this material seems to be highly suitable for sulfur reduction in commercial fuels in order to meet regulatory requirements and demands for automotive exhaust catalysis-systems or exhaust gas sensors. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Physiology and genetics of sulfur-oxidizing bacteria.

    Science.gov (United States)

    Friedrich, C G

    1998-01-01

    Reduced inorganic sulfur compounds are oxidized by members of the domains Archaea and Bacteria. These compounds are used as electron donors for anaerobic phototrophic and aerobic chemotrophic growth, and are mostly oxidized to sulfate. Different enzymes mediate the conversion of various reduced sulfur compounds. Their physiological function in sulfur oxidation is considered (i) mostly from the biochemical characterization of the enzymatic reaction, (ii) rarely from the regulation of their formation, and (iii) only in a few cases from the mutational gene inactivation and characterization of the resulting mutant phenotype. In this review the sulfur-metabolizing reactions of selected phototrophic and of chemotrophic prokaryotes are discussed. These comprise an archaeon, a cyanobacterium, green sulfur bacteria, and selected phototrophic and chemotrophic proteobacteria. The genetic systems are summarized which are presently available for these organisms, and which can be used to study the molecular basis of their dissimilatory sulfur metabolism. Two groups of thiobacteria can be distinguished: those able to grow with tetrathionate and other reduced sulfur compounds, and those unable to do so. This distinction can be made irrespective of their phototrophic or chemotrophic metabolism, neutrophilic or acidophilic nature, and may indicate a mechanism different from that of thiosulfate oxidation. However, the core enzyme for tetrathionate oxidation has not been identified so far. Several phototrophic bacteria utilize hydrogen sulfide, which is considered to be oxidized by flavocytochrome c owing to its in vitro activity. However, the function of flavocytochrome c in vivo may be different, because it is missing in other hydrogen sulfide-oxidizing bacteria, but is present in most thiosulfate-oxidizing bacteria. A possible function of flavocytochrome c is discussed based on biophysical studies, and the identification of a flavocytochrome in the operon encoding enzymes involved

  1. Process for removal of sulfur compounds from fuel gases

    Science.gov (United States)

    Moore, Raymond H.; Stegen, Gary E.

    1978-01-01

    Fuel gases such as those produced in the gasification of coal are stripped of sulfur compounds and particulate matter by contact with molten metal salt. The fuel gas and salt are intimately mixed by passage through a venturi or other constriction in which the fuel gas entrains the molten salt as dispersed droplets to a gas-liquid separator. The separated molten salt is divided into a major and a minor flow portion with the minor flow portion passing on to a regenerator in which it is contacted with steam and carbon dioxide as strip gas to remove sulfur compounds. The strip gas is further processed to recover sulfur. The depleted, minor flow portion of salt is passed again into contact with the fuel gas for further sulfur removal from the gas. The sulfur depleted, fuel gas then flows through a solid absorbent for removal of salt droplets. The minor flow portion of the molten salt is then recombined with the major flow portion for feed to the venturi.

  2. Physiology of alkaliphilic sulfur-oxidizing bacteria from soda lakes

    NARCIS (Netherlands)

    Banciu, H.L.

    2004-01-01

    The inorganic sulfur oxidation by obligate haloalkaliphilic chemolithoautotrophs was only recently discovered and investigated. These autotrophic sulfur oxidizing bacteria (SOB), capable of oxidation of inorganic sulfur compounds at moderate to high salt concentration and at high pH, can be divided

  3. Denitrification of groundwater using a sulfur-oxidizing autotrophic denitrifying anaerobic fluidized-bed MBR: performance and bacterial community structure.

    Science.gov (United States)

    Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Qu, Jiuhui

    2015-03-01

    This paper investigates a novel sulfur-oxidizing autotrophic denitrifying anaerobic fluidized bed membrane bioreactor (AnFB-MBR) that has the potential to overcome the limitations of conventional sulfur-oxidizing autotrophic denitrification systems. The AnFB-MBR produced consistent high-quality product water when fed by a synthetic groundwater with NO3 (-)-N ranging 25-80 mg/L and operated at hydraulic retention times of 0.5-5.0 h. A nitrate removal rate of up to 4.0 g NO3 (-)-N/Lreactord was attained by the bioreactor, which exceeded any reported removal capacity. The flux of AnFB-MBR was maintained in the range of 1.5-15 L m(-2) h(-1). Successful membrane cleaning was practiced with cleaning cycles of 35-81 days, which had no obvious effect on the AnFB-MBR performance. The (15) N-tracer analyses elucidated that nitrogen was converted into (15) N2-N and (15) N-biomass accounting for 88.1-93.1 % and 6.4-11.6 % of the total nitrogen produced, respectively. Only 0.3-0.5 % of removed nitrogen was in form of (15)N2O-N in sulfur-oxidizing autotrophic denitrification process, reducing potential risks of a significant amount of N2O emissions. The sulfur-oxidizing autotrophic denitrifying bacterial consortium was composed mainly of bacteria from Proteobacteria, Chlorobi, and Chloroflexi phyla, with genera Thiobacillus, Sulfurimonas, and Ignavibacteriales dominating the consortium. The pyrosequencing assays also suggested that the stable microbial communities corresponded to the elevated performance of the AnFB-MBR. Overall, this research described relatively high nitrate removal, acceptable flux, indicating future potential for the technology in practice.

  4. Hydrogen sulfide oxidation by a microbial consortium in a recirculation reactor system: sulfur formation under oxygen limitation and removal of phenols.

    Science.gov (United States)

    Alcantara, Sergio; Velasco, Antonio; Muñoz, Ana; Cid, Juan; Revah, Sergio; Razo-Flores, Elías

    2004-02-01

    Wastewater from petroleum refining may contain a number of undesirable contaminants including sulfides, phenolic compounds, and ammonia. The concentrations of these compounds must be reduced to acceptable levels before discharge. Sulfur formation and the effect of selected phenolic compounds on the sulfide oxidation were studied in autotrophic aerobic cultures. A recirculation reactor system was implemented to improve the elemental sulfur recovery. The relation between oxygen and sulfide was determined calculating the O2/S2- loading rates (Q(O2)/Q(S)2- = Rmt), which adequately defined the operation conditions to control the sulfide oxidation. Sulfur-producing steady states were achieved at Rmt ranging from 0.5 to 1.5. The maximum sulfur formation occurred at Rmt of 0.5 where 85% of the total sulfur added to the reactor as sulfide was transformed to elemental sulfur and 90% of it was recovered from the bottom of the reactor. Sulfide was completely oxidized to sulfate (Rmt of 2) in a stirred tank reactor, even when a mixture of phenolic compounds was present in the medium. Microcosm experiments showed that carbon dioxide production increased in the presence of the phenols, suggesting that these compounds were oxidized and that they may have been used as carbon and energy source by heterotrophic microorganisms present in the consortium.

  5. Process for removing sulfur from sulfur-containing gases: high calcium fly-ash

    Science.gov (United States)

    Rochelle, Gary T.; Chang, John C. S.

    1991-01-01

    The present disclosure relates to improved processes for treating hot sulfur-containing flue gas to remove sulfur therefrom. Processes in accordance with the present invention include preparing an aqueous slurry composed of a calcium alkali source and a source of reactive silica and/or alumina, heating the slurry to above-ambient temperatures for a period of time in order to facilitate the formation of sulfur-absorbing calcium silicates or aluminates, and treating the gas with the heat-treated slurry components. Examples disclosed herein demonstrate the utility of these processes in achieving improved sulfur-absorbing capabilities. Additionally, disclosure is provided which illustrates preferred configurations for employing the present processes both as a dry sorbent injection and for use in conjunction with a spray dryer and/or bagfilter. Retrofit application to existing systems is also addressed.

  6. Effects of sulfur oxides on eicosanoids

    International Nuclear Information System (INIS)

    Chen, L.C.; Miller, P.D.; Amdur, M.O.

    1989-01-01

    Ultrafine metal oxides and SO2 react during coal combustion or smelting operations to form primary emissions coated with an acidic SOx layer. Ongoing work in this laboratory has examined the effects of sulfur oxides on pulmonary functions of guinea pigs. We have previously reported that 20 micrograms/m3 acidic sulfur oxide as a surface layer on ultrafine ZnO particles decreases lung volumes, decreases carbon monoxide diffusing capacity, and causes lung inflammation in guinea pigs after 4 daily 3-h exposures. It also produces bronchial hypersensitivity following a single 1-h exposure. The importance of this surface layer is demonstrated by our observation that 200 micrograms/m3 of sulfuric acid droplets of equivalent size are needed to produce the same degree of hypersensitivity. This study characterized the concentration-dependent effects of in vivo exposures to sulfur oxides on arachidonic acid metabolism in the guinea pig lung, and investigated the time course and the relation between eicosanoid composition and pulmonary functions. We focused specifically on four cyclooxygenase metabolites of arachidonic acid, that is, prostaglandins (PG) E1, F2 alpha, 6-keto prostaglandin F1 alpha, and thromboxane (Tx) B2, and two groups of sulfidopeptide leukotrienes (C4, D4, E4, and F4). Guinea pigs were exposed to ultrafine ZnO aerosol (count median diameter = 0.05 microns, sigma g = 1.80) with a layer of acidic sulfur oxide on the surface of the particles. Lung lavage was collected after exposures, and the levels of arachidonic acid metabolites were determined using radioimmunoassay (RIA). Concentration-dependent promotion of PGF2 alpha and concentration-dependent suppression of LtB4 were observed. The increased PGF2 alpha was associated with depressed vital capacity and diffusing capacity of the lungs measured in guinea pigs exposed to the same atmosphere described in a previous study

  7. Confine sulfur in mesoporous metal–organic framework @ reduced graphene oxide for lithium sulfur battery

    International Nuclear Information System (INIS)

    Bao, Weizhai; Zhang, Zhian; Qu, Yaohui; Zhou, Chengkun; Wang, Xiwen; Li, Jie

    2014-01-01

    Highlights: • Metal organic framework @ reduced graphene oxide was applied for sulfur cathode. • MIL-101(Cr)@rGO/S composites are synthesized by a facile two-step liquid method. • Cycling stability of MIL-101(Cr)@rGO/S sulfur cathode was improved. -- Abstract: Mesoporous metal organic framework @ reduced graphene oxide (MIL-101(Cr)@rGO) materials have been used as a host material to prepare the multi-composite sulfur cathode through a facile and effective two-step liquid phase method successfully, which is different from the simple MIL-101(Cr)/S mixed preparation method. The successful reduced graphene oxide coating in the MIL-101(Cr)@rGO improve the electronic conductivity of meso-MOFs effectively. The discharge capacity and capacity retention rate of MIL-101(Cr)@rGO/S composite sulfur cathode are as high as 650 mAh g −1 and 66.6% at the 50th cycle at the current density of 335 mA g −1 . While the discharge capacity and capacity retention rate of MIL-101(Cr)/S mixed sulfur cathode is 458 mAh g −1 and 37.3%. Test results indicate that the MIL-101(Cr)@rGO is a promising host material for the sulfur cathode in the lithium–sulfur battery applications

  8. Effects of reactive element additions and sulfur removal on the oxidation behavior of FECRAL alloys

    International Nuclear Information System (INIS)

    Stasik, M.C.; Pettit, F.S.; Meier, G.H.; Smialek, J.L.

    1994-01-01

    The results of this study have shown that desulfurization of FeCrAl alloys by hydrogen annealing can result in improvements in cyclic oxidation comparable to that achieved by doping with reactive elements. Moreover, specimens of substantial thicknesses can be effectively desulfurized because of the high diffusivity of sulfur in bcc iron alloys. The results have also shown that there is less stress generation during the cyclic oxidation of Y-doped FeCrAl compared to Ti-doped or desulfurized FeCrAl. This indicates that the growth mechanism, as well as the strength of the oxide/alloy interface, influences the ultimate oxidation morphology and stress state which will certainly affect the length of time the alumina remains protective

  9. Identification of major planktonic sulfur oxidizers in stratified freshwater lake.

    Directory of Open Access Journals (Sweden)

    Hisaya Kojima

    Full Text Available Planktonic sulfur oxidizers are important constituents of ecosystems in stratified water bodies, and contribute to sulfide detoxification. In contrast to marine environments, taxonomic identities of major planktonic sulfur oxidizers in freshwater lakes still remain largely unknown. Bacterioplankton community structure was analyzed in a stratified freshwater lake, Lake Mizugaki in Japan. In the clone libraries of 16S rRNA gene, clones very closely related to a sulfur oxidizer isolated from this lake, Sulfuritalea hydrogenivorans, were detected in deep anoxic water, and occupied up to 12.5% in each library of different water depth. Assemblages of planktonic sulfur oxidizers were specifically analyzed by constructing clone libraries of genes involved in sulfur oxidation, aprA, dsrA, soxB and sqr. In the libraries, clones related to betaproteobacteria were detected with high frequencies, including the close relatives of Sulfuritalea hydrogenivorans.

  10. Mechanisms and evolution of oxidative sulfur metabolism in green sulfur bacteria

    DEFF Research Database (Denmark)

    Gregersen, Lea Haarup; Bryant, Donald A.; Frigaard, Niels-Ulrik

    2011-01-01

    Green sulfur bacteria (GSB) constitute a closely related group of photoautotrophic and thiotrophic bacteria with limited phenotypic variation. They typically oxidize sulfide and thiosulfate to sulfate with sulfur globules as an intermediate. Based on genome sequence information from 15 strains...... product is further oxidized to sulfite by the dissimilatory sulfite reductase (DSR) system. This system consists of components horizontally acquired partly from sulfide-oxidizing and partly from sulfate-reducing bacteria. Depending on the strain, the sulfite is probably oxidized to sulfate by one of two...... in sulfate formation in other bacteria has been replaced by the DSR system in GSB. Sequence analyses suggested that the conserved soxJXYZAKBW gene cluster was horizontally acquired by Chlorobium phaeovibrioides DSM 265 from the Chlorobaculum lineage and that this acquisition was mediated by a mobile genetic...

  11. Characterization and uranium bioleaching performance of mixed iron- and sulfur-oxidizers versus iron-oxidizers

    International Nuclear Information System (INIS)

    Qian Li; Jing Sun; Dexin Ding; Qingliang Wang; Wenge Shi; Eming Hu; Xiaoyu Jiang; University of South China, Hengyang; Xingxing Wang

    2017-01-01

    In order to develop and apply mixed iron- and sulfur-oxidizers in uranium bioleaching, the characteristics of a mixed iron- and sulfur-oxidizing consortium (Consortium ISO) were comparatively investigated versus an iron-oxidizing consortium (Consortium IO). The results showed, the Consortium ISO exerted stronger oxidative ability and acid-producing ability than Consortium IO did. The synergy of sulfur-oxidizers and iron-oxidizers could change the structure and properties of the passivation substance, and work positively for eliminating the accumulation of passivation substance. In the bioleaching process, the uranium bioleaching experiments showed the recovery percentage of uranium reached 99.5% with Consortium ISO, 6.3% more than that of Consortium IO. (author)

  12. Integrated Science Assessment (ISA) for Sulfur Oxides ...

    Science.gov (United States)

    This draft document provides EPA’s evaluation and synthesis of the most policy-relevant science related to the health effects of sulfur oxides. When final, it will provide a critical part of the scientific foundation for EPA’s decision regarding the adequacy of the current primary (health-based) National Ambient Air Quality Standard (NAAQS) for sulfur dioxide. The references considered for inclusion in or cited in the external review draft ISA are available at https://hero.epa.gov/hero/sulfur-oxides. The intent of the ISA, according to the CAA, is to “accurately reflect the latest scientific knowledge expected from the presence of [a] pollutant in ambient air” (U.S. Code, 1970a, 1970b). It includes an assessment of scientific research from atmospheric sciences, exposure sciences, dosimetry, mode of action, animal and human toxicology, and epidemiology. Key information and judgments formerly found in the Air Quality Criteria Documents (AQCDs) for sulfur oxides (SOx) are included; Annexes provide additional details supporting the ISA. Together, the ISA and Annexes serve to update and revise the last SOx ISA which was published in 2008.

  13. Interfacial and electrical properties of HfAlO/GaSb metal-oxide-semiconductor capacitors with sulfur passivation

    International Nuclear Information System (INIS)

    Tan Zhen; Zhao Lian-Feng; Wang Jing; Xu Jun

    2014-01-01

    Interfacial and electrical properties of HfAlO/GaSb metal-oxide-semiconductor capacitors (MOSCAPs) with sulfur passivation were investigated and the chemical mechanisms of the sulfur passivation process were carefully studied. It was shown that the sulfur passivation treatment could reduce the interface trap density D it of the HfAlO/GaSb interface by 35% and reduce the equivalent oxide thickness (EOT) from 8 nm to 4 nm. The improved properties are due to the removal of the native oxide layer, as was proven by x-ray photoelectron spectroscopy measurements and high-resolution cross-sectional transmission electron microscopy (HRXTEM) results. It was also found that GaSb-based MOSCAPs with HfAlO gate dielectrics have interfacial properties superior to those using HfO 2 or Al 2 O 3 dielectric layers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Advanced treatment technique for swine wastewater using two agents: Thermally polymerized amorphous silica and hydrated lime for color and phosphorus removal and sulfur for nitrogen removal.

    Science.gov (United States)

    Hasegawa, Teruaki; Kurose, Yohei; Tanaka, Yasuo

    2017-10-01

    The efficacy of advanced treatment of swine wastewater using thermally polymerized, modified amorphous silica and hydrated lime (M-CSH-lime) for color and phosphorus removal and sulfur for nitrogen removal was examined with a demonstration-scale treatment plant. The color removal rate was approximately 78% at M-CSH-lime addition rates of > 0.055 wt/v%. The PO43--P removal rate exceeded 99.9% with > 0.023 wt/v%. pH of the effluent from the M-CSH-lime reactor increased with the addition rate till a maximum value of 12.7, which was effective in disinfection. The recovered M-CSH-lime would be suitable as a phosphorus fertilizer because the total P 2 O 5 content was approximately 10%. The nitrogen oxide (NOx-N) removal rate by sulfur denitrification increased to approximately 80% when the NOx-N loading rate was around 0.1 kg-N/ton-S/day. It was suggested that the combination of the two processes would be effective in the advanced treatment of swine wastewater. © 2017 Japanese Society of Animal Science.

  15. Ultrasound-assisted oxidative desulfurization of bitumen

    Science.gov (United States)

    Kamal, Wan Mohamad Ikhwan bin Wan; Okawa, Hirokazu; Kato, Takahiro; Sugawara, Katsuyasu

    2017-07-01

    Bitumen contains a high percentage of sulfur (about 4.6 wt %). A hydrodesulfurization method is used to remove sulfur from bitumen. The drawback of this method is the requirement for a high temperature of >300 °C. Most of the sulfur in bitumen exists as thiophene. Oxidative desulfurization (ODS), involving oxidizing sulfur using H2O2, then removing it using NaOH, allows the removal of sulfur in thiophene at low temperatures. We removed sulfur from bitumen using ODS treatment under ultrasound irradiation, and 52% of sulfur was successfully removed. Additionally, the physical action of ultrasound assisted the desulfurization of bitumen, even at low H2O2 concentrations.

  16. Laboratory simulated slipstream testing of novel sulfur removal processes for gasification application

    International Nuclear Information System (INIS)

    Schmidt, Roland; Tsang, Albert; Cross, Joe; Summers, Clinton; Kornosky, Bob

    2008-01-01

    The Wabash River Integrated Methanol and Power Production from Clean Coal Technologies (IMPPCCT) project is investigating an Early Entrance Coproduction Plant (EECP) concept to evaluate integrated electrical power generation and methanol production from coal and other carbonaceous feedstocks. Research, development and testing (RD and T) that is currently being conducted under the project is evaluating cost effective process systems for removing contaminants, particularly sulfur species, from the generated gas which contains mainly synthesis gas (syngas), CO 2 and steam at concentrations acceptable for the methanol synthesis catalyst. The RD and T includes laboratory testing followed by bench-scale and field testing at the SG Solutions Gasification Plant located in West Terre Haute, Indiana. Actual synthesis gas produced by the plant was utilized at system pressure and temperature for bench-scale field testing. ConocoPhillips Company (COP) developed a sulfur removal technology based on a novel, regenerable sorbent - S Zorb trademark - to remove sulfur contaminants from gasoline at high temperatures. The sorbent was evaluated for its sulfur removal performance from the generated syngas especially in the presence of other components such as water and CO 2 which often cause sorbent performance to decline over time. This publication also evaluates the performance of a regenerable activated carbon system developed by Nucon International, Inc. in polishing industrial gas stream by removing sulfur species to parts-per-billion (ppb) levels. (author)

  17. Selective removal of methyl mercaptan in coffee aroma using oxidized microporous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Sakano, T. [Ajinomoto General Foods Inc., Tokyo (Japan). Central Research Laboratoties; Tamon, H.; Okazaki, M. [Kyoto University, Kyoto (Japan). Dept. of Chemical Engineering

    1999-10-01

    Coffee aroma recovered from the extraction process of roasted coffee beans is used to improve the quality of soluble coffee products. Coffee aroma often has an irritating sulfurous odor. In the present work, it is experimentally elucidated that methyl mercaptan could be selectively removed from the coffee aroma-containing gas by the oxidized microporous carbon. Breakthrough curves of coffee aroma-containing gas on zeolite 5A, microporous carbon (MSC 5A), and MSC 5A oxidized with 13.2N HNO{sub 3} aqueous solution revealed that the adsorption capacity of methyl mercaptan on the oxidized carbon was 4.2 times of that on the zeolite. The loss of desired coffee aroma was decreased using the oxidized carbon in the removal of methyl mercaptan. (author)

  18. Plutonium oxides analysis. Sulfur potentiometric analysis

    International Nuclear Information System (INIS)

    Anon.

    Total sulfur determination (sulfur, sulfates, sulfides ...) in plutonium oxides, suitable for sulfate ion content between 0.003 percent to 0.2 percent, by dissolution in nitric hydrofluoric acid, nitrates elimination, addition of hydrochloric acid and reduction in hydrogen sulfide which is carried by an inert gas and neutralized by sodium hydroxide. Sodium sulfide is titrated with mercuric acetate by constant intensity potentiometry [fr

  19. Production of petroleum bitumen by oxidation of heavy oil residue with sulfur

    Science.gov (United States)

    Tileuberdi, Ye.; Akkazyn, Ye. A.; Ongarbayev, Ye. K.; Imanbayev, Ye. I.; Mansurov, Z. A.

    2018-03-01

    In this paper production of bitumen adding elemental sulfur at oxidation of oil residue are investigated. The objects of research were distilled residue of Karazhanbas crude oil and elemental sulfur. These oil residue characterized by a low output of easy fractions and the high content of tar-asphaltene substances, therefore is the most comprehensible feedstock for producing bitumen. The sulfur is one of the oil product collected in oil extraction regions. Oxidation process of hydrocarbons carried out at temperatures from 180 up to 210 °С without addition of sulfur and with the addition of sulfur (5-10 wt. %) for 4 hours. At 200 °С oxidation of hydrocarbons with 5, 7 and 10 wt.% sulfur within 3-4 h allows receiving paving bitumen on the mark BND 200/300, BND 130/200, BN 90/130 and BN 70/30. Physical and mechanical characteristics of oxidation products with the addition of 5-7 wt. % sulfur corresponds to grade of paving bitumen BND 40/60. At the given temperature oxidized for 2.5-3 h, addition of 10 wt. % sulfur gave the products of oxidation describing on parameters of construction grades of bitumen (BN 90/10).

  20. Action of sulfurous oxide on plants

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, J

    1873-01-01

    In order to ascertain which trees best withstand the action of sulfurous oxide, and are, therefore, best suited for planting in neighborhoods where this gas is given off, young trees of various kinds growing in the open ground, were exposed under glass shades to air containing quantities of sulfurous oxide, varying from 1/10,000 to 1/70,000, under circumstances most favorable to its action, viz., in direct sunlight and after having been watered. The sensitiveness of the leaves was carefully noticed, and also the power which the trees possessed of compensating for injury by the reproduction of leaves; this was found to vary considerably in different trees, as did also the resisting power in the first case. Alder, sycamore, ash, and especially maple, are recommended for growth where exposed to smoke containing sulfurous oxide; next follow birch, hornbeam, and oak, and last, beech. The pines did not give constant results, but in nature they suffer more than other trees, and this is owing to the fact that, although their sensitiveness at first is less than that of other trees, their power of restoring lost leaves is much less.

  1. Efficient removal of sulfur hexafluoride (SF6) through reacting with recycled electroplating sludge.

    Science.gov (United States)

    Zhang, Jia; Zhou, Ji Zhi; Liu, Qiang; Qian, Guangren; Xu, Zhi Ping

    2013-06-18

    This paper reports that recycled electroplating sludge is able to efficiently remove greenhouse gas sulfur hexafluoride (SF6). The removal process involves various reactions of SF6 with the recycled sludge. Remarkably, the sludge completely removed SF6 at a capacity of 1.10 mmol/g (SF6/sludge) at 600 °C. More importantly, the evolved gases were SO2, SiF4, and a limited amount of HF, with no toxic SOF4, SO2F2, or SF4 being detected. These generated gases can be readily captured and removed by NaOH solution. The reacted solids were further found to be various metal fluorides, thus revealing that SF6 removal takes place by reacting with various metal oxides and silicate in the sludge. Moreover, the kinetic investigation revealed that the SF6 reaction with the sludge is a first-order chemically controlled process. This research thus demonstrates that the waste electroplating sludge can be potentially used as an effective removal agent for one of the notorious greenhouse gases, SF6.

  2. ADVANCED SULFUR CONTROL CONCEPTS

    Energy Technology Data Exchange (ETDEWEB)

    Apostolos A. Nikolopoulos; Santosh K. Gangwal; William J. McMichael; Jeffrey W. Portzer

    2003-01-01

    Conventional sulfur removal in integrated gasification combined cycle (IGCC) power plants involves numerous steps: COS (carbonyl sulfide) hydrolysis, amine scrubbing/regeneration, Claus process, and tail-gas treatment. Advanced sulfur removal in IGCC systems involves typically the use of zinc oxide-based sorbents. The sulfides sorbent is regenerated using dilute air to produce a dilute SO{sub 2} (sulfur dioxide) tail gas. Under previous contracts the highly effective first generation Direct Sulfur Recovery Process (DSRP) for catalytic reduction of this SO{sub 2} tail gas to elemental sulfur was developed. This process is currently undergoing field-testing. In this project, advanced concepts were evaluated to reduce the number of unit operations in sulfur removal and recovery. Substantial effort was directed towards developing sorbents that could be directly regenerated to elemental sulfur in an Advanced Hot Gas Process (AHGP). Development of this process has been described in detail in Appendices A-F. RTI began the development of the Single-step Sulfur Recovery Process (SSRP) to eliminate the use of sorbents and multiple reactors in sulfur removal and recovery. This process showed promising preliminary results and thus further process development of AHGP was abandoned in favor of SSRP. The SSRP is a direct Claus process that consists of injecting SO{sub 2} directly into the quenched coal gas from a coal gasifier, and reacting the H{sub 2}S-SO{sub 2} mixture over a selective catalyst to both remove and recover sulfur in a single step. The process is conducted at gasifier pressure and 125 to 160 C. The proposed commercial embodiment of the SSRP involves a liquid phase of molten sulfur with dispersed catalyst in a slurry bubble-column reactor (SBCR).

  3. Methane oxidation in presence of sulfur dioxide

    International Nuclear Information System (INIS)

    Mantashyan, A.A.; Avetisyan, A.M.; Makaryan, E.M.; Wang, H.

    2006-01-01

    The emission of sulfurous gases including SO 2 from stationary power generation remains to be a serious environmental and ecological problem. Sulfurous gases are almost entirely produced from the combustion of sulfur-containing fuels. While fuel desulfurization and flue gas scrubbing is a viable solution, in the developing countries it remains to be an economical challenge to implement these SO x reduction technologies. The oxidation of methane in presence of sulfurous gas (SO 2 ) addition was studied experimentally. Te experiments were conducted in a static reactor at temperature of 728-786 K, and for mixture of C 4 /O 2 ≡ 1/2 at a pressure of 117 Torr with varying amount of SO 2 addition. It was observed that SO 2 addition accelerated the oxidation process, reduced the induction period and increased the extent of methane consumption. At the relatively short resident time (less than 50 sec) SO 3 was detected, but at longer residence time SO 3 was reduced spontaneously to SO 2

  4. Gas cleaning and hydrogen sulfide removal for COREX coal gas by sorption enhanced catalytic oxidation over recyclable activated carbon desulfurizer.

    Science.gov (United States)

    Sun, Tonghua; Shen, Yafei; Jia, Jinping

    2014-02-18

    This paper proposes a novel self-developed JTS-01 desulfurizer and JZC-80 alkaline adsorbent for H2S removal and gas cleaning of the COREX coal gas in small-scale and commercial desulfurizing devices. JTS-01 desulfurizer was loaded with metal oxide (i.e., ferric oxides) catalysts on the surface of activated carbons (AC), and the catalyst capacity was improved dramatically by means of ultrasonically assisted impregnation. Consequently, the sulfur saturation capacity and sulfur capacity breakthrough increased by 30.3% and 27.9%, respectively. The whole desulfurizing process combined selective adsorption with catalytic oxidation. Moreover, JZC-80 adsorbent can effectively remove impurities such as HCl, HF, HCN, and ash in the COREX coal gas, stabilizing the system pressure drop. The JTS-01 desulfurizer and JZC-80 adsorbent have been successfully applied for the COREX coal gas cleaning in the commercial plant at Baosteel, Shanghai. The sulfur capacity of JTS-01 desulfurizer can reach more than 50% in industrial applications. Compared with the conventional dry desulfurization process, the modified AC desulfurizers have more merit, especially in terms of the JTS-01 desulfurizer with higher sulfur capacity and low pressure drop. Thus, this sorption enhanced catalytic desulfurization has promising prospects for H2S removal and other gas cleaning.

  5. Quantification of Discrete Oxide and Sulfur Layers on Sulfur-Passivated InAs by XPS

    National Research Council Canada - National Science Library

    Petrovykh, D. Y; Sullivan, J. M; Whitman, L. J

    2005-01-01

    .... The S-passivated InAs(001) surface can be modeled as a sulfur-indium-arsenic layer-cake structure, such that characterization requires quantification of both arsenic oxide and sulfur layers that are at most a few monolayers thick...

  6. Investigation on thiosulfate-involved organics and nitrogen removal by a sulfur cycle-based biological wastewater treatment process.

    Science.gov (United States)

    Qian, Jin; Lu, Hui; Cui, Yanxiang; Wei, Li; Liu, Rulong; Chen, Guang-Hao

    2015-02-01

    Thiosulfate, as an intermediate of biological sulfate/sulfite reduction, can significantly improve nitrogen removal potential in a biological sulfur cycle-based process, namely the Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI(®)) process. However, the related thiosulfate bio-activities coupled with organics and nitrogen removal in wastewater treatment lacked detailed examinations and reports. In this study, S2O3(2-) transformation during biological SO4(2-)/SO3(2-) co-reduction coupled with organics removal as well as S2O3(2-) oxidation coupled with chemolithotrophic denitrification were extensively evaluated under different experimental conditions. Thiosulfate is produced from the co-reduction of sulfate and sulfite through biological pathway at an optimum pH of 7.5 for organics removal. And the produced S2O3(2-) may disproportionate to sulfide and sulfate during both biological S2O3(2-) reduction and oxidation most possibly carried out by Desulfovibrio-like species. Dosing the same amount of nitrate, pH was found to be the more direct factor influencing the denitritation activity than free nitrous acid (FNA) and the optimal pH for denitratation (7.0) and denitritation (8.0) activities were different. Spiking organics significantly improved both denitratation and denitritation activities while minimizing sulfide inhibition of NO3(-) reduction during thiosulfate-based denitrification. These findings in this study can improve the understanding of mechanisms of thiosulfate on organics and nitrogen removal in biological sulfur cycle-based wastewater treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Capital cost: high and low sulfur coal plants-1200 MWe. [High sulfur coal

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    This Commercial Electric Power Cost Study for 1200 MWe (Nominal) high and low sulfur coal plants consists of three volumes. The high sulfur coal plant is described in Volumes I and II, while Volume III describes the low sulfur coal plant. The design basis and cost estimate for the 1232 MWe high sulfur coal plant is presented in Volume I, and the drawings, equipment list and site description are contained in Volume II. The reference design includes a lime flue gas desulfurization system. A regenerative sulfur dioxide removal system using magnesium oxide is also presented as an alternate in Section 7 Volume II. The design basis, drawings and summary cost estimate for a 1243 MWe low sulfur coal plant are presented in Volume III. This information was developed by redesigning the high sulfur coal plant for burning low sulfur sub-bituminous coal. These coal plants utilize a mechanical draft (wet) cooling tower system for condenser heat removal. Costs of alternate cooling systems are provided in Report No. 7 in this series of studies of costs of commercial electrical power plants.

  8. Comparative analysis of the mechanisms of sulfur anion oxidation and reduction by dsr operon to maintain environmental sulfur balance.

    Science.gov (United States)

    Ghosh, Semanti; Bagchi, Angshuman

    2015-12-01

    Sulfur metabolism is one of the oldest known redox geochemical cycles in our atmosphere. These redox processes utilize different sulfur anions and the reactions are performed by the gene products of dsr operon from phylogenetically diverse sets of microorganisms. The operon is involved in the maintenance of environmental sulfur balance. Interestingly, the dsr operon is found to be present in both sulfur anion oxidizing and reducing microorganisms and in both types of organisms DsrAB protein complex plays a vital role. Though there are various reports regarding the genetics of dsr operon there are practically no reports dealing with the structural aspects of sulfur metabolism by dsr operon. In our present study, we tried to compare the mechanisms of sulfur anion oxidation and reduction by Allochromatium vinosum and Desulfovibrio vulgaris respectively through DsrAB protein complex. We analyzed the modes of bindings of sulfur anions to the DsrAB protein complex and observed that for sulfur anion oxidizers, sulfide and thiosulfate are the best substrates whereas for reducers sulfate and sulfite have the best binding abilities. We analyzed the binding interaction pattern of the DsrA and DsrB proteins while forming the DsrAB protein complexes in Desulfovibrio vulgaris and Allochromatium vinosum. To our knowledge this is the first report that analyzes the differences in binding patterns of sulfur substrates with DsrAB protein from these two microorganisms. This study would therefore be essential to predict the biochemical mechanism of sulfur anion oxidation and reduction by these two microorganisms i.e., Desulfovibrio vulgaris (sulfur anion reducer) and Allochromatium vinosum (sulfur anion oxidizer). Our observations also highlight the mechanism of sulfur geochemical cycle which has important implications in future study of sulfur metabolism as it has a huge application in waste remediation and production of industrial bio-products viz. vitamins, bio-polyesters and bio

  9. Thermal dynamic analysis of sulfur removal from coal by electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Gao, J.; Meng, F. [Qinghua University, Beijing (China). Dept. of Thermal Engineering

    2002-06-01

    The electrolytic reactions about sulfur removal from coal were studied by using chemical thermal dynamic analysis. According to the thermodynamical data, the Gibbs free energy value of the electrolytic reactions of pyritic and organic sulfur removal from coal is higher than zero. So, these electrolytic reactions are not spontaneous chemical reactions. In order to carry out desulfurisation by electrolysis, a certain voltage is necessary and important. Because theoretic decomposition voltage of pyrite and some parts of organic sulfur model compound is not very high, electrolysis reactions are easily to be carried out by using electrolysis technology. Mn ion and Fe ion are added into electrolysis solutions to accelerate the desulfurisation reaction. The electrolytic decomposition of coal is discussed. Because the theoretical decomposition voltage of some organic model compound is not high, the coal decomposition might happen. 17 refs., 4 tabs.

  10. A novel hydrogen oxidizer amidst the sulfur-oxidizing Thiomicrospira lineage

    Science.gov (United States)

    Hansen, Moritz; Perner, Mirjam

    2015-01-01

    Thiomicrospira species are ubiquitously found in various marine environments and appear particularly common in hydrothermal vent systems. Members of this lineage are commonly classified as sulfur-oxidizing chemolithoautotrophs. Although sequencing of Thiomicrospira crunogena's genome has revealed genes that encode enzymes for hydrogen uptake activity and for hydrogenase maturation and assembly, hydrogen uptake ability has so far not been reported for any Thiomicrospira species. We isolated a Thiomicrospira species (SP-41) from a deep sea hydrothermal vent and demonstrated that it can oxidize hydrogen. We show in vivo hydrogen consumption, hydrogen uptake activity in partially purified protein extracts and transcript abundance of hydrogenases during different growth stages. The ability of this strain to oxidize hydrogen opens up new perspectives with respect to the physiology of Thiomicrospira species that have been detected in hydrothermal vents and that have so far been exclusively associated with sulfur oxidation. PMID:25226028

  11. Dissimilatory oxidation and reduction of elemental sulfur in thermophilic archaea.

    Science.gov (United States)

    Kletzin, Arnulf; Urich, Tim; Müller, Fabian; Bandeiras, Tiago M; Gomes, Cláudio M

    2004-02-01

    The oxidation and reduction of elemental sulfur and reduced inorganic sulfur species are some of the most important energy-yielding reactions for microorganisms living in volcanic hot springs, solfataras, and submarine hydrothermal vents, including both heterotrophic, mixotrophic, and chemolithoautotrophic, carbon dioxide-fixing species. Elemental sulfur is the electron donor in aerobic archaea like Acidianus and Sulfolobus. It is oxidized via sulfite and thiosulfate in a pathway involving both soluble and membrane-bound enzymes. This pathway was recently found to be coupled to the aerobic respiratory chain, eliciting a link between sulfur oxidation and oxygen reduction at the level of the respiratory heme copper oxidase. In contrast, elemental sulfur is the electron acceptor in a short electron transport chain consisting of a membrane-bound hydrogenase and a sulfur reductase in (facultatively) anaerobic chemolithotrophic archaea Acidianus and Pyrodictium species. It is also the electron acceptor in organoheterotrophic anaerobic species like Pyrococcus and Thermococcus, however, an electron transport chain has not been described as yet. The current knowledge on the composition and properties of the aerobic and anaerobic pathways of dissimilatory elemental sulfur metabolism in thermophilic archaea is summarized in this contribution.

  12. Effect of Nitrogen Oxides on Elemental Mercury Removal by Nanosized Mineral Sulfide.

    Science.gov (United States)

    Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Lee, Po-Heng; Feng, Yong; Shih, Kaimin

    2017-08-01

    Because of its large surface area, nanosized zinc sulfide (Nano-ZnS) has been demonstrated in a previous study to be efficient for removal of elemental mercury (Hg 0 ) from coal combustion flue gas. The excellent mercury adsorption performance of Nano-ZnS was found to be insusceptible to water vapor, sulfur dioxide, and hydrogen chloride. However, nitrogen oxides (NO X ) apparently inhibited mercury removal by Nano-ZnS; this finding was unlike those of many studies on the promotional effect of NO X on Hg 0 removal by other sorbents. The negative effect of NO X on Hg 0 adsorption over Nano-ZnS was systematically investigated in this study. Two mechanisms were identified as primarily responsible for the inhibitive effect of NO X on Hg 0 adsorption over Nano-ZnS: (1) active sulfur sites on Nano-ZnS were oxidized to inactive sulfate by NO X ; and (2) the chemisorbed mercury, i.e., HgS, was reduced to Hg 0 by NO X . This new insight into the role of NO X in Hg 0 adsorption over Nano-ZnS can help to optimize operating conditions, maximize Hg 0 adsorption, and facilitate the application of Nano-ZnS as a superior alternative to activated carbon for Hg 0 removal using existing particulate matter control devices in power plants.

  13. Sulfur removal from fuel using zeolites/polyimide mixed matrix membrane adsorbents

    International Nuclear Information System (INIS)

    Lin, Ligang; Wang, Andong; Dong, Meimei; Zhang, Yuzhong; He, Benqiao; Li, Hong

    2012-01-01

    Graphical abstract: Membrane adsorption process is proposed for sulfur removal. Three-dimensional network structure is key to fulfill adsorption function of MMMs, which adsorption/desorption behavior is markedly related with binding force with sulfur molecules. Highlights: ► Membrane adsorption process is proposed for sulfur removal. ► Three-dimensional network structure of MMMs is key to fulfill adsorption function. ► Adsorption/desorption behavior is markedly related with binding force. - Abstract: A novel membrane adsorption process was proposed for the sulfur removal from fuels. The mixed matrix membranes (MMMs) adsorbents composed of polyimide (PI) and various Y zeolites were prepared. By the detailed characterization of FT-IR, morphology, thermal and mechanical properties of MMMs adsorbents, combining the adsorption and desorption behavior research, the process–structure–function relationship was discussed. Field-emission scanning electron microscope (FESEM) images show that the functional particles are incorporated into the three-dimensional network structure. MMMs adsorbents with 40% of zeolites content possess better physical properties, which was confirmed by mechanical strength and thermo stability analysis. Influence factors including post-treatment, content of incorporated zeolites, adsorption time, temperature, initial sulfur concentration as well as sulfur species on the adsorption performance of MMMs adsorbents have been evaluated. At 4 wt.% zeolites content, adsorption capacity for NaY/PI, AgY/PI and CeY/PI MMMs adsorbents come to 2.0, 7.5 and 7.9 mg S/g, respectively. And the regeneration results suggest that the corresponding spent membranes can recover about 98%, 90% and 70% of the desulfurization capacity, respectively. The distinct adsorption and desorption behavior of MMMs adsorbents with various functional zeolites was markedly related with their various binding force and binding mode with sulfur compounds.

  14. Sulfur-centered reactive intermediates derived from the oxidation of sulfur compounds of biological interest

    Energy Technology Data Exchange (ETDEWEB)

    Abedinzadeh, Z. [Lab. de Chimie Physique, UMR, Univ. Rene Descartes, Paris (France)

    2001-02-01

    Sulphur compounds play a central role in the structure and activity of many vital systems. In the living cell, sulfur constitutes an essential part of the defense against oxidative damage and is transformed into a variety of sulfur free radical species. Many studies of the chemistry of sulfur-centered radicals using pulse radiolysis and photolysis techniques to detect and measure the kinetics of these radicals have been published and reviewed. This paper discusses the present state of research on the formation and reactivity of certain sulfur-centered radicals [RS{sup .}, RSS{sup .}, RS{sup .+}, (RSSR){sup .+}] and their implications for biological systems. (author)

  15. Sulfur-centered reactive intermediates derived from the oxidation of sulfur compounds of biological interest

    International Nuclear Information System (INIS)

    Abedinzadeh, Z.

    2001-01-01

    Sulphur compounds play a central role in the structure and activity of many vital systems. In the living cell, sulfur constitutes an essential part of the defense against oxidative damage and is transformed into a variety of sulfur free radical species. Many studies of the chemistry of sulfur-centered radicals using pulse radiolysis and photolysis techniques to detect and measure the kinetics of these radicals have been published and reviewed. This paper discusses the present state of research on the formation and reactivity of certain sulfur-centered radicals [RS . , RSS . , RS .+ , (RSSR) .+ ] and their implications for biological systems. (author)

  16. Performance evaluation of pilot scale sulfur-oxidizing denitrification for treatment of metal plating wastewater.

    Science.gov (United States)

    Flores, Angel S P; Gwon, Eun-Mi; Sim, Dong-Min; Nisola, Grace; Galera, Melvin M; Chon, Seung-Se; Chung, Wook-Jin; Pak, Dae-Won; Ahn, Zou Sam

    2006-01-01

    A full-scale and two pilot-scale upflow sulfur-oxidizing denitrification (SOD) columns were evaluated using metal plating wastewater as feed. The sludge was autotrophically enriched, and inoculated in the SOD columns attached to the effluent line of three metal plating wastewater treatment facilities. The effects of activated carbon and aeration were also studied, and found effective for the removal of suspended solids and ammonia, respectively. The results showed that the constituents, such as the total nitrogen, nitrates, nitrites, ammonia, chemical oxygen demand (COD), and heavy metals, were effectively removed. The pH was observed to be maintained at 7-8 due to the alkalinity supplied by the sulfur-calcium carbonate (SC) pellet. The denitrification efficiency and start-up period were observed to be affected by the influent quality. Chromium, iron, nickel, copper, and zinc--the major heavy metal components of the influent--were effectively reduced at certain concentrations. Other metal ions were also detected and reduced to undetectable concentrations, but no trends in the comparison with denitrification were observed. From the results it can be concluded that SOD is effective for the removal of nitrogen, particularly nitrates, without a drastic pH change, and can effectively remove minute concentrations of heavy metals and COD in metal plating wastewaters.

  17. Characterization of desulfurization, denitrogenation and process sulfur transfer during hydropyrolysis of Chinese high sulfur coals

    Energy Technology Data Exchange (ETDEWEB)

    Sun Chenggong; Li Baoqing [Chinese Academy of Sciences, Taiyuan (China). State Key Lab. of Coal Conversion; Snape, C.E. [Strathclyde Univ., Glasgow (United Kingdom). Dept. of Pure and Applied Chemistry

    1997-12-31

    The process desulphurization and denitrogenation of Chinese high sulfur coals and the characteristics of sulfur transformation during non-catalytic hydropyrolysis were investigated by a 10 g fixed-bed reactor and a small-scaled reactor with online spectrometry respectively. It was indicated that more than 70% of the total sulfur of the two high sulfur coals and almost all pyritic sulfur are removed as H{sub 2}S, leaving the char and tar products with much less sulfur distribution. The liability of sulfur transformation to tar products is closely related to the thiophenic structure forms rather than sulfidic forms. At the same time, the formation of trace amount of sulfur dioxide indicates the presence of inherent sulfur oxidation reactions inside coal frame structures even under H{sub 2} pressure. (orig.)

  18. Synthesis and characterization of sulfur functionalized graphene oxide nanosheets as efficient sorbent for removal of Pb2+, Cd2+, Ni2+ and Zn2+ ions from aqueous solution: A combined thermodynamic and kinetic studies

    Science.gov (United States)

    Pirveysian, Mahtab; Ghiaci, Mehran

    2018-01-01

    A very simple, one pot method was used for preparation of sulfur functionalized graphene oxide (GO-SOxR) with sodium sulfide and water in reflux condition. The elemental analysis data showed high sulfur content up to 15%. EDS and XPS analysis also proved introduction of sulfur element. To make the sorbent more efficient operationally, the GO-SOxR was coated with a mesoporous shell of TiO2 or SiO2. The prepared sorbents were characterized by SEM, TEM, TGA, XPS, XRD, IR and EDS. GO-SOxR@TiO2 and GO-SOxR@SiO2 composites were tested for removal of Pb(II), Cd(II), Ni(II) and Zn(II) as heavy metal ions from aqueous solution in batch method. Adsorption of the heavy metal ions was studied kinetically, and the adsorption capacities of GO-SOxR, GO-SOxR@TiO2, and GO-SOxR@SiO2 were evaluated using equilibrium adsorption isotherms, and compared to other adsorbents used for removal of these heavy metals. Kinetic studies showed that the experimental data was fitted with pseudo second order model. The adsorption capacity of GO was significantly improved by sulfur functionalization and TiO2 coating.

  19. Reduced graphene oxide encapsulated sulfur spheres for the lithium-sulfur battery cathode

    Directory of Open Access Journals (Sweden)

    Feiyan Liu

    Full Text Available Reduced graphene oxide (rGO encapsulated sulfur spheres for the Li-S batteries were prepared via the redox reaction between sodium polysulfide. XRD spectra showed that the diffraction peak of graphite oxide (GO at 10° disappeared, while the relatively weak diffraction peak at 27° belongs to graphene emerged. FT-IR spectra showed that the vibrations of the functional groups of GO, such as 3603 cm−1, 1723 cm−1and 1619 cm−1 which contributed from OH, COC and CO respectively, disappeared when compared to the spectra of GSC. SEM observations indicated that the optimum experimental condition followed as: mass ratio of GO and S was 1:1, 10% NaOH was used to adjust the pH. EDX analysis showed that the sulfur content reached at 68.8% of the composite material. The resultant electric resistance was nearly less than GO’s resistance in three orders of magnitude under same condition. Further electrochemical performance tests showed a coulombic efficiency was 96% from the first cycle capacity was 827 mAh g−1, to 388 mAh g−1 in the 100 cycles. This study carries substantial significance to the development of Li-S battery cathode materials. Keywords: Lithium-sulfur battery, Graphene, Sulfur spheres, Cathode material

  20. Mesoporous binary metal oxide nanocomposites: Synthesis, characterization and decontamination of sulfur mustard

    Energy Technology Data Exchange (ETDEWEB)

    Praveen Kumar, J., E-mail: praveenjella10@gmail.com; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Singh, Beer; Gopi, T.; Krishna, R.

    2016-04-15

    Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. They were synthesized by precipitation pyrolysis method and characterized by means of transmission electron microscopy, scanning electron microscopy coupled with energy dispersive analysis of X rays, X ray diffraction, and nitrogen adsorption techniques. The transmission electron microscopy and nitrogen adsorption data indicated the presence of pores with diameter ranging from 10 to 70 nm in the binary metal oxide nanocomposites and these materials exhibited surface area values in the range of 76–134 m{sup 2}/g. These binary metal oxide nanocomposites demonstrated large decontamination efficiencies against sulfur mustard when compared to their single component metal oxide nanoparticles. The binary metal oxide nanocomposites effectively decontaminated sulfur mustard into relatively non toxic products such as chloro ethyl vinyl sulfide, divinyl sulfide, 1,4-oxathiane, etc. The promising decontamination properties of binary metal oxide nanocomposites against sulfur mustard were attributed to the basic sites, Lewis acid sites, and the presence of these sites was confirmed by CO{sub 2} and NH{sub 3} temperature programmed desorption. - Graphical abstract: Mesoporous MnO{sub 2}–ZnO, Fe{sub 2}O{sub 3}–ZnO, NiO–ZnO, and CeO{sub 2}–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard. - Highlights: • Binary metal oxide nanocomposites were synthesized by co-precipitation method. • They were studied as sorbent decontaminants against sulfur mustard. • They decontaminated sulfur mustard into non toxic products. • MnO{sub 2}–ZnO and CeO{sub 2}–ZnO nanocomposites showed greater decontamination efficiency.

  1. Performance of a pilot-scale packed bed reactor for perchlorate reduction using a sulfur oxidizing bacterial consortium.

    Science.gov (United States)

    Boles, Amber R; Conneely, Teresa; McKeever, Robert; Nixon, Paul; Nüsslein, Klaus R; Ergas, Sarina J

    2012-03-01

    A novel sulfur-utilizing perchlorate reducing bacterial consortium successfully treated perchlorate (ClO₄⁻) in prior batch and bench-scale packed bed reactor (PBR) studies. This study examined the scale up of this process for treatment of water from a ClO ₄⁻ and RDX contaminated aquifer in Cape Cod Massachusetts. A pilot-scale upflow PBR (∼250-L) was constructed with elemental sulfur and crushed oyster shell packing media. The reactor was inoculated with sulfur oxidizing ClO₄⁻ reducing cultures enriched from a wastewater seed. Sodium sulfite provided a good method of dissolved oxygen removal in batch cultures, but was found to promote the growth of bacteria that carry out sulfur disproportionation and sulfate reduction, which inhibited ClO₄⁻ reduction in the pilot system. After terminating sulfite addition, the PBR successfully removed 96% of the influent ClO₄⁻ in the groundwater at an empty bed contact time (EBCT) of 12 h (effluent ClO₄⁻ of 4.2 µg L(-1)). Simultaneous ClO₄⁻ and NO₃⁻ reduction was observed in the lower half of the reactor before reactions shifted to sulfur disproportionation and sulfate reduction. Analyses of water quality profiles were supported by molecular analysis, which showed distinct groupings of ClO₄⁻ and NO₃⁻ degrading organisms at the inlet of the PBR, while sulfur disproportionation was the primary biological process occurring in the top potion of the reactor. Copyright © 2011 Wiley Periodicals, Inc.

  2. Adsorption/oxidation of sulfur-containing gases on nitrogen-doped activated carbon

    Directory of Open Access Journals (Sweden)

    Liu Qiang

    2016-01-01

    Full Text Available Coconut shell-based activated carbon (CAC was used for the removal of methyl mercaptan (MM. CAC was modified by urea impregnation and calcined at 450°C and 950°C. The desulfurization activity was determined in a fixed bed reactor under room temperature. The results showed that the methyl mercaptan adsorption/oxidation capacity of modified carbon caicined at 950°C is more than 3 times the capacity of original samples. On the other hand, the modified carbon caicined at 950°C also has a high capacity for the simultaneous adsorption/oxidation of methyl mercaptan and hydrogen sulfide.The introduce of basic nitrogen groups siginificantly increases the desulfurization since it can facilitate the electron transfer process between sulfur and oxygen. The structure and chemical properties are characterized using Boehm titration, N2 adsorption-desorption method, thermal analysis and elemental analysis. The results showed that the major oxidation products were dimethyl disulfide and methanesulfonic acid which adsorbed in the activated carbon.

  3. Removal of hydrogen sulfide and sulfur dioxide by carbons impregnated with triethylenediamine.

    Science.gov (United States)

    Wu, Li-Chun; Chang, Tsu-Hua; Chung, Ying-Chien

    2007-12-01

    Activated carbon (AC) adsorption has long been considered to be a readily available technology for providing protection against exposure to acutely toxic gases. However, ACs without chemical impregnation have proven to be much less efficient than impregnated ACs in terms of gas removal. The impregnated ACs in current use are usually modified with metalloid impregnation agents (ASC-carbons; copper, chromium, or silver) to simultaneously enhance the chemical and physical properties of the ACs in removing specific poisonous gases. These metalloid agents, however, can cause acute poisoning to both humans and the environment, thereby necessitating the search for organic impregnation agents that present a much lower risk. The aim of the study reported here was to assess AC or ASC-carbon impregnated with triethylenediamine (TEDA) in terms of its adsorption capability for simulated hydrogen sulfide (H2S) and sulfur dioxide (SO2) gases. The investigation was undergone in a properly designed laboratory-scale and industrial fume hood evaluation. Using the system reported here, we obtained a significant adsorption: the removal capability for H2S and SO2 was 375 and 229 mg/g-C, respectively. BET measurements, element analysis, scanning electron microscopy, and energy dispersive spectrometry identified the removal mechanism for TEDA-impregnated AC to be both chemical and physical adsorption. Chemical adsorption and oxidation were the primary means by which TEDA-impregnated ASC-carbons removed the simulated gases.

  4. Sulfur isotope fractionation during oxidation of sulfur dioxide: gas-phase oxidation by OH radicals and aqueous oxidation by H2O2, O3 and iron catalysis

    Directory of Open Access Journals (Sweden)

    J. N. Crowley

    2012-01-01

    Full Text Available The oxidation of SO2 to sulfate is a key reaction in determining the role of sulfate in the environment through its effect on aerosol size distribution and composition. Sulfur isotope analysis has been used to investigate sources and chemical processes of sulfur dioxide and sulfate in the atmosphere, however interpretation of measured sulfur isotope ratios is challenging due to a lack of reliable information on the isotopic fractionation involved in major transformation pathways. This paper presents laboratory measurements of the fractionation factors for the major atmospheric oxidation reactions for SO2: Gas-phase oxidation by OH radicals, and aqueous oxidation by H2O2, O3 and a radical chain reaction initiated by iron. The measured fractionation factor for 34S/32S during the gas-phase reaction is αOH = (1.0089±0.0007−((4±5×10−5 T(°C. The measured fractionation factor for 34S/32S during aqueous oxidation by H2O2 or O3 is αaq = (1.0167±0.0019−((8.7±3.5 ×10−5T(°C. The observed fractionation during oxidation by H2O2 and O3 appeared to be controlled primarily by protonation and acid-base equilibria of S(IV in solution, which is the reason that there is no significant difference between the fractionation produced by the two oxidants within the experimental error. The isotopic fractionation factor from a radical chain reaction in solution catalysed by iron is αFe = (0.9894±0.0043 at 19 °C for 34S/32S. Fractionation was mass-dependent with regards to 33S/32S for all the reactions investigated. The radical chain reaction mechanism was the only measured reaction that had a faster rate for the light isotopes. The results presented in this study will be particularly useful to determine the importance of the transition metal-catalysed oxidation pathway compared to other oxidation pathways, but other main oxidation pathways can not be distinguished based on stable sulfur isotope measurements alone.

  5. Sulfur metabolism in phototrophic sulfur bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Dahl, Christiane

    2008-01-01

    Phototrophic sulfur bacteria are characterized by oxidizing various inorganic sulfur compounds for use as electron donors in carbon dioxide fixation during anoxygenic photosynthetic growth. These bacteria are divided into the purple sulfur bacteria (PSB) and the green sulfur bacteria (GSB......). They utilize various combinations of sulfide, elemental sulfur, and thiosulfate and sometimes also ferrous iron and hydrogen as electron donors. This review focuses on the dissimilatory and assimilatory metabolism of inorganic sulfur compounds in these bacteria and also briefly discusses these metabolisms...... in other types of anoxygenic phototrophic bacteria. The biochemistry and genetics of sulfur compound oxidation in PSB and GSB are described in detail. A variety of enzymes catalyzing sulfur oxidation reactions have been isolated from GSB and PSB (especially Allochromatium vinosum, a representative...

  6. Manganese-Loaded Activated Carbon for the Removal of Organosulfur Compounds from High-Sulfur Diesel Fuels

    OpenAIRE

    Al-Ghouti, M.A.; Al-Degs, Y.S.

    2014-01-01

    The adsorptive capacity of activated carbon (AC) is significantly enhanced toward weakly interacting organosulfur compounds (OSC) from sulfur-rich diesel fuel. Sulfur compounds are selectively removed from diesel after surface modification by manganese dioxide (MnO2). A selective surface for OSC removal was created by loading MnO2 on the surface; π-complexation between the partially filled d-orbitals of Mn4+ and the S atom is the controlling mechanism for OSC removal. Principal component anal...

  7. Nitrate removal from aquaculture effluents using woodchip bioreactors improved by adding sulfur granules and crushed seashells

    DEFF Research Database (Denmark)

    von Ahnen, Mathis; Pedersen, Per Bovbjerg; Dalsgaard, Johanne

    2018-01-01

    This study examined the effects on nitrate removal when adding sulfur granules and crushed seashells to a woodchip bioreactor treating aquaculture effluents. Using a central composite design, the two components were added at three levels (0.000, 0.125 and 0.250 m3/m3 bioreactor volume) to 13......, the inclusion of crushed seashells together with sulfur granules helped to maintain the pH above 7.4 and prevent a production (i.e., release) of nitrite. According to the modeled response surfaces, a sulfur granule:crushed seashell:woodchip mixture ratio containing about 0.2 m3 sulfur granules and 0.1 m3...... crushed seashells per m3 reactor volume would give the best results with respect to high N removal and minimal nitrite release. In conclusion, the study showed that N removal in woodchip bioreactors may be improved by adding sulfur granules and seashells, contributing to the optimization of woodchip...

  8. Sensing sulfur oxides and other sulfur bearing pollutants with solid electrolyte pellets. I. Gas concentration cells

    Energy Technology Data Exchange (ETDEWEB)

    Chamberland, A M; Gauthier, J M

    1977-01-01

    A new sensing technique using a solid electrolyte has been demonstrated for sulfur-bearing pollutants. Based on potentiometric measurements across a pellet of potassium sulfate, this sensor allows concentrations of sulfur dioxides, sulfur trioxide, hydrogen sulfide, methyl mercaptan and carbonyl sulfide in air to be measured with accuracy. Its operational concentration range at the present time is 0.1 ppM up to at least 10,000 ppM. The presence of other common pollutants such as carbon dioxide, methane, nitric oxide and nitrogen dioxide does not interfere with the measurement of air samples containing sulfur-bearing pollutants.

  9. Study of the reduction of sulfur dioxide to elemental sulfur by carbon monoxide on a La/sub 0/ /sub 5/ Sr/sub 0/ /sub 5/ CoO/sub 3/ catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hibbert, D B; Tseung, A C.C.

    1979-12-01

    A study of the reduction of sulfur dioxide to elemental sulfur by carbon monoxide on a La/sub 0/ /sub 5/ Sr/sub 0/ /sub 5/ CoO/sub 3/ catalyst a perovskite oxide, to determine the effects of oxygen and water on SO2 reduction showed that in the presence of 5 to 16% oxygen, the reaction between sulfur dioxide and carbon monoxide still occurred if there was sufficient carbon monoxide in the gas to react with all the oxygen. At 600C, all the sulfur dioxide was removed at 5 to 16% oxygen levels. Water vapor at 2% did not adversely affect the reaction. The unwanted by-products, hydrogen disulfide and carbonyl sulfide, were reduced at contact times below 0.25 sec. During the reaction, the catalyst itself reacted with sulfur to give metal sulfides. When reagent grade CO/sub 2/O/sub 3/ was substituted for perovskite oxide, the maximum conversion of 98% of sulfur dioxide was attained at 550C, but an unacceptably high concentration of carbonyl sulfide was formed; within 1 hr, the sulfur dioxide conversion fell to 60%. The perovskite oxide reaction may be useful in removing sulfur dioxide from fosill fuel stack gases.

  10. Biodesulfurization techniques: Application of selected microorganisms for organic sulfur removal from coals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Elmore, B.B.

    1993-08-01

    As an alternative to post-combustion desulfurization of coal and pre-combustion desulfurization using physicochemical techniques, the microbial desulfurization of coal may be accomplished through the use of microbial cultures that, in an application of various microbial species, may remove both the pyritic and organic fractions of sulfur found in coal. Organisms have been isolated that readily depyritize coal but often at prohibitively low rates of desulfurization. Microbes have also been isolated that may potentially remove the organic-sulfur fraction present in coal (showing promise when acting on organic sulfur model compounds such as dibenzothiophene). The isolation and study of microorganisms demonstrating a potential for removing organic sulfur from coal has been undertaken in this project. Additionally, the organisms and mechanisms by which coal is microbially depyritized has been investigated. Three cultures were isolated that grew on dibenzothiophene (DBT), a model organic-sulfur compound, as the sole sulfur source. These cultures (UMX3, UMX9, and IGTS8) also grew on coal samples as the sole sulfur source. Numerous techniques for pretreating and ``cotreating`` coal for depyritization were also evaluated for the ability to improve the rate or extent of microbial depyritization. These include prewashing the coal with various solvents and adding surfactants to the culture broth. Using a bituminous coal containing 0.61% (w/w) pyrite washed with organic solvents at low slurry concentrations (2% w/v), the extent of depyritization was increased approximately 25% in two weeks as compared to controls. At slurry concentrations of 20% w/v, a tetrachloroethylene treatment of the coal followed by depyritization with Thiobacillus ferrooxidans increased both the rate and extent of depyritization by approximately 10%.

  11. Simultaneous nitrogen and phosphorus removal in the sulfur cycle-associated Enhanced Biological Phosphorus Removal (EBPR) process.

    Science.gov (United States)

    Wu, Di; Ekama, George A; Wang, Hai-Guang; Wei, Li; Lu, Hui; Chui, Ho-Kwong; Liu, Wen-Tso; Brdjanovic, Damir; van Loosdrecht, Mark C M; Chen, Guang-Hao

    2014-02-01

    Hong Kong has practiced seawater toilet flushing since 1958, saving 750,000 m(3) of freshwater every day. A high sulfate-to-COD ratio (>1.25 mg SO4(2-)/mg COD) in the saline sewage resulting from this practice has enabled us to develop the Sulfate reduction, Autotrophic denitrification and Nitrification Integrated (SANI(®)) process with minimal sludge production and oxygen demand. Recently, the SANI(®) process has been expanded to include Enhanced Biological Phosphorus Removal (EBPR) in an alternating anaerobic/limited-oxygen (LOS-EBPR) aerobic sequencing batch reactor (SBR). This paper presents further development - an anaerobic/anoxic denitrifying sulfur cycle-associated EBPR, named as DS-EBPR, bioprocess in an alternating anaerobic/anoxic SBR for simultaneous removal of organics, nitrogen and phosphorus. The 211 day SBR operation confirmed the sulfur cycle-associated biological phosphorus uptake utilizing nitrate as electron acceptor. This new bioprocess cannot only reduce operation time but also enhance volumetric loading of SBR compared with the LOS-EBPR. The DS-EBPR process performed well at high temperatures of 30 °C and a high salinity of 20% seawater. A synergistic relationship may exist between sulfur cycle and biological phosphorus removal as the optimal ratio of P-release to SO4(2-)-reduction is close to 1.0 mg P/mg S. There were no conventional PAOs in the sludge. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. In situ tribochemical sulfurization of molybdenum oxide nanotubes.

    Science.gov (United States)

    Rodríguez Ripoll, Manel; Tomala, Agnieszka; Gabler, Christoph; DraŽić, Goran; Pirker, Luka; Remškar, Maja

    2018-02-15

    MoS 2 nanoparticles are typically obtained by high temperature sulfurization of organic and inorganic precursors under a S rich atmosphere and have excellent friction reduction properties. We present a novel approach for making the sulfurization unnecessary for MoO 3 nanotubes during the synthesis process for friction and wear reduction applications while simultaneously achieving a superb tribological performance. To this end, we report the first in situ sulfurization of MoO 3 nanotubes during sliding contact in the presence of sulfur-containing lubricant additives. The sulfurization leads to the tribo-chemical formation of a MoS 2 -rich low-friction tribofilm as verified using Raman spectroscopy and can be achieved both during sliding contact and under extreme pressure conditions. Under sliding contact conditions, MoO 3 nanotubes in synergy with sulfurized olefin polysulfide and pre-formed zinc dialkyl dithiophosphate tribofilms achieve an excellent friction performance. Under these conditions, the tribochemical sulfurization of MoO 3 nanotubes leads to a similar coefficient of friction to the one obtained using a model nanolubricant containing MoS 2 nanotubes. Under extreme pressure conditions, the in situ sulfurization of MoO 3 nanotubes using sulfurized olefin polysulfide results in a superb load carrying capacity capable of outperforming MoS 2 nanotubes. The reason is that while MoO 3 nanotubes are able to continuously sulfurize during sliding contact conditions, MoS 2 nanotubes progressively degrade by oxidation thus losing lubricity.

  13. Method for removing heavy metal and nitrogen oxides from flue gas, device for removing heavy metal and nitrogen oxides from flue gas

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hann-Sheng; Livengood, Charles David

    1997-12-01

    A method for the simultaneous removal of oxides and heavy metals from a fluid is provided comprising combining the fluid with compounds containing alkali and sulfur to create a mixture; spray drying the mixture to create a vapor phase and a solid phase; and isolating the vapor phase from the solid phase. A device is also provided comprising a means for spray-drying flue gas with alkali-sulfide containing liquor at a temperature sufficient to cause the flue gas to react with the compounds so as to create a gaseous fraction and a solid fraction and a means for directing the gaseous fraction to a fabric filter.

  14. A binder-free sulfur/reduced graphene oxide aerogel as high performance electrode materials for lithium sulfur batteries

    Science.gov (United States)

    Nitze, Florian; Agostini, Marco; Lundin, Filippa; Palmqvist, Anders E. C.; Matic, Aleksandar

    2016-12-01

    Societies’ increasing need for energy storage makes it necessary to explore new concepts beyond the traditional lithium ion battery. A promising candidate is the lithium-sulfur technology with the potential to increase the energy density of the battery by a factor of 3-5. However, so far the many problems with the lithium-sulfur system have not been solved satisfactory. Here we report on a new approach utilizing a self-standing reduced graphene oxide based aerogel directly as electrodes, i.e. without further processing and without the addition of binder or conducting agents. We can thereby disrupt the common paradigm of “no battery without binder” and can pave the way to a lithium-sulfur battery with a high practical energy density. The aerogels are synthesized via a one-pot method and consist of more than 2/3 sulfur, contained inside a porous few-layered reduced graphene oxide matrix. By combining the graphene-based aerogel cathode with an electrolyte and a lithium metal anode, we demonstrate a lithium-sulfur cell with high areal capacity (more than 3 mAh/cm2 after 75 cycles), excellent capacity retention over 200 cycles and good sulfur utilization. Based on this performance we estimate that the energy density of this concept-cell can significantly exceed the Department of Energy (DEO) 2020-target set for transport applications.

  15. Facilitated and selective oxidation of thiophenic sulfur compounds using MoOx/Al₂O₃-H₂O₂ system under ultrasonic irradiation.

    Science.gov (United States)

    Akbari, Azam; Omidkhah, Mohammadreza; Towfighi Darian, Jafar

    2015-03-01

    Oxidative desulfurization of thiophenic sulfur compounds of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) with MoOx/Al₂O₃ catalyst and H₂O₂ oxidant has been facilitated and more selective under ultrasonic irradiation. The catalyst with the optimum 10% of Mo loading consisted of isolated tetrahedral molybdenum oxide species based on FTIR analysis. The increase of Mo loading to 15% and 20% caused to generation of polymolybdate and MoO₃ crystals which decreased desulfurization activity. Sonication enhanced the apparent reaction rate constants in oxidation of all three sulfur compounds. An increase in the Arrhenius factor (A0), which is the total number of collisions per second, could explain the acceleration in the rate constants by sonication. The apparent activated energy (Ea) of BT oxidation was reduced from 96.6 to 75.3 kJ/mol by using ultrasound. This indicated that ultrasound had also a chemical effect, like a catalytic influence, in the acceleration of BT removal. DBT oxidation was reduced when investigated in the presence of tetralin, naphthalene and 2-methyl naphthalene as the model aromatic compounds of actual light oils. A higher selectivity toward DBT elimination in the presence of aromatics was obtained by sonication when compared with the silent treatment. Ultrasound cleaned the catalyst surface from adsorbed aromatics. On the basis of the obtained results, a mechanistic proposal for this desulfurization was explained. Oxidation was performed by nucleophilic attack of sulfur atom to the molybdenum peroxide species of tetrahedral molybdates, which was more advanced by sonication. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Removals of aqueous sulfur dioxide and hydrogen sulfide using CeO2-NiAl-LDHs coating activated carbon and its mix with carbon nano-tubes

    KAUST Repository

    Li, Jing; Chen, Fangping; Jin, Guanping; Feng, Xiaoshuang; Li, Xiaoxuan

    2015-01-01

    Ce-doped NiAl/layered double hydroxide was coated at activated carbon by urea hydrolysis method (CeO2-NiAl-LDHs/AC) in one pot, which was characterized by X-ray diffraction, infrared spectra, field emission scanning electron microscope and electrochemical techniques. CeO2-NiAl-LDHs/AC shows good uptake for aqueous sulfur dioxide (483.09mg/g) and hydrogen sulfide (181.15mg/g), respectively at 25°C. Meanwhile, the electrochemical removals of aqueous sulfur dioxide and hydrogen sulfide were respectively investigated at the mix of CeO2-NiAl-LDHs/AC and carbon nano-tubes modified homed paraffin-impregnated electrode. Both sulfur dioxide and hydrogen sulfide could be effectively oxidized to sulfuric acid at 1.0V in alkaline aqueous solution. © 2015 Elsevier B.V.

  17. Removals of aqueous sulfur dioxide and hydrogen sulfide using CeO2-NiAl-LDHs coating activated carbon and its mix with carbon nano-tubes

    KAUST Repository

    Li, Jing

    2015-07-01

    Ce-doped NiAl/layered double hydroxide was coated at activated carbon by urea hydrolysis method (CeO2-NiAl-LDHs/AC) in one pot, which was characterized by X-ray diffraction, infrared spectra, field emission scanning electron microscope and electrochemical techniques. CeO2-NiAl-LDHs/AC shows good uptake for aqueous sulfur dioxide (483.09mg/g) and hydrogen sulfide (181.15mg/g), respectively at 25°C. Meanwhile, the electrochemical removals of aqueous sulfur dioxide and hydrogen sulfide were respectively investigated at the mix of CeO2-NiAl-LDHs/AC and carbon nano-tubes modified homed paraffin-impregnated electrode. Both sulfur dioxide and hydrogen sulfide could be effectively oxidized to sulfuric acid at 1.0V in alkaline aqueous solution. © 2015 Elsevier B.V.

  18. Desulfurization of organic sulfur from a subbituminous coal by electron-transfer process with K{sub 4}(Fe(CN){sub 6})

    Energy Technology Data Exchange (ETDEWEB)

    Dipu Borah [Pragjyotika J College, Titabar (India). Department of Chemistry

    2006-02-01

    The desulfurization reaction involving direct electron transfer from potassium ferrocyanide, K{sub 4}(Fe(CN){sub 6}), successfully removed organic sulfur from a subbituminous coal. The temperature variation of desulfurization revealed that increase of temperature enhanced the level of sulfur removal. Moreover, the desulfurization reaction was found to be dependent on the concentration of K{sub 4}(Fe(CN){sub 6}). Gradual increase in the concentration of K{sub 4}(Fe(CN){sub 6}) raised the magnitude of desulfurization, but at higher concentration the variation was not significant. The removal of organic sulfur from unoxidized coal slightly increased with reduced particle size. Desulfurization from oxidized coals (prepared by aerial oxidation) revealed a higher level of sulfur removal in comparison to unoxidized coal. Highest desulfurization of 36.4 wt % was obtained at 90{sup o}C and 0.1 M concentration of K{sub 4}(Fe(CN){sub 6}) in the 100-mesh size oxidized coal prepared at 200{sup o}C. Model sulfur compound study revealed that aliphatic types of sulfur compounds are primarily responsible for desulfurization. Because of higher stability, thiophene and condensed thiophene-type of compounds perhaps remained unaffected by the electron-transfer agent. Infrared study revealed the formation of oxidized sulfur compounds (sulfoxide, sulfone, sulfonic acid, etc.) in the oxidized coals. The desulfurization reaction in different systems is well-represented by the pseudo-first-order kinetic model. Application of the transition state theory indicated that the desulfurization reaction proceeds with the absorption of heat (endothermic reaction) and is nonspontaneous in nature. 53 refs., 6 figs., 3 tabs.

  19. Effect of antimony oxide on magnesium vanadates for the selective oxidation of hydrogen sulfide to sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Li, K.T.; Chi, Z.H. [Department of Chemical Engineering, Tunghai University, ROC Taichung (Taiwan)

    2001-05-17

    The effect of antimony oxide addition to MgV{sub 2}O{sub 6} and Mg{sub 3}V{sub 2}O{sub 8} was studied in the selective oxidation of hydrogen sulfide to sulfur. Significant improvements in sulfur selectivity and yield were observed for the uncalcined mechanical mixtures of magnesium vanadates with {alpha}-Sb{sub 2}O{sub 4}. Calcination of the mechanical mixtures resulted in the much stronger synergy in catalytic activity and sulfur selectivity. For the uncalcined samples, XRD, TPR and XPS studies indicated that antimony reduction behaviors in the mechanical mixtures differed very much from those in {alpha}-Sb{sub 2}O{sub 4} alone, suggested that their selectivity improvements might be due to the interactions (probably oxygen transfer) between {alpha}-Sb{sub 2}O{sub 4} and magnesium vanadates. For the calcined samples, XRD results indicated that their better catalytic performances in H{sub 2}S oxidation were primarily attributed to the formation of VSbO{sub 4} compound from antimony oxide and magnesium vanadates.

  20. Micro-Spherical Sulfur/Graphene Oxide Composite via Spray Drying for High Performance Lithium Sulfur Batteries

    Science.gov (United States)

    Tian, Yuan; Sun, Zhenghao; Zhang, Yongguang; Yin, Fuxing

    2018-01-01

    An efficient, industry-accepted spray drying method was used to synthesize micro-spherical sulfur/graphene oxide (S/GO) composites as cathode materials within lithium sulfur batteries. The as-designed wrapping of the sulfur-nanoparticles, with wrinkled GO composites, was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The unique morphological design of this material enabled superior discharge capacity and cycling performance, demonstrating a high initial discharge capacity of 1400 mAh g−1 at 0.1 C. The discharge capacity remained at 828 mAh g−1 after 150 cycles. The superior electrochemical performance indicates that the S/GO composite improves electrical conductivity and alleviates the shuttle effect. This study represents the first time such a facile spray drying method has been adopted for lithium sulfur batteries and used in the fabrication of S/GO composites. PMID:29346303

  1. Bioenergetic studies of coal sulfur oxidation by extremely thermophilic bacteria. Final report, September 15, 1992--August 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.M.; Han, C.J.

    1997-12-31

    Thermoacidophilic microorganisms have been considered for inorganic sulfur removal from coal because of expected improvements in rates of both biotic and abiotic sulfur oxidation reactions with increasing temperature. In this study, the bioenergetic response of the extremely thermoacidophilic archaeon, Metallosphaera sedula, to environmental changes have been examined in relation to its capacity to catalyze pyrite oxidation in coal. Given an appropriate bioenergetic challenge, the metabolic response was to utilize additional amounts of energy sources (i.e., pyrite) to survive. Of particular interest were the consequences of exposing the organism to various forms of stress (chemical, nutritional, thermal, pH) in the presence of coal pyrite. Several approaches to take advantage of stress response to accelerate pyrite oxidation by this organism were examined, including attempts to promote acquired thermal tolerance to extend its functional range, exposure to chemical uncouplers and decouplers, and manipulation of heterotrophic and chemolithotrophic tendencies to optimize biomass concentration and biocatalytic activity. Promising strategies were investigated in a continuous culture system. This study identified environmental conditions that promote better coupling of biotic and abiotic oxidation reactions to improve biosulfurization rates of thermoacidophilic microorganisms.

  2. Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments.

    Science.gov (United States)

    Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

    2015-11-01

    A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration--a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder.

  3. Effects of sulfur dioxide and nitric oxide on mercury oxidation and reduction under homogeneous conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yongxin Zhao; Michael D. Mann; Edwin S. Olson; John H. Pavlish; Grant E. Dunham [University of North Dakota, Grand Forks, ND (United States). Department of Chemical Engineering

    2006-05-15

    This paper is particularly related to elemental mercury (Hg{sup 0}) oxidation and divalent mercury (Hg{sup 2+} reduction under simulated flue gas conditions in the presence of nitric oxide (NO) and sulfur dioxide (SO{sub 2}). As a powerful oxidant and chlorinating reagent, Cl{sub 2} has the potential for Hg oxidation. However, the detailed mechanism for the interactions, especially among chlorine (Cl)-containing species, SO{sub 2}, NO, as well as H{sub 2}O, remains ambiguous. Research described in this paper therefore focused on the impacts of SO{sub 2} and NO on Hg{sup 0} oxidation and Hg{sup 2+} reduction with the intent of unraveling unrecognized interactions among Cl species, SO{sub 2}, and NO most importantly in the presence of H{sub 2}O. The experimental results demonstrated that SO{sub 2} and NO had pronounced inhibitory effects on Hg{sup 0} oxidation at high temperatures when H{sub 2}O was also present in the gas blend. Such a demonstration was further confirmed by the reduction of Hg{sup 2+} back into its elemental form. Data revealed that SO{sub 2} and NO were capable of promoting homogeneous reduction of Hg{sup 2+} to Hg{sup 0} with H{sub 2}O being present. However, the above inhibition or promotion disappeared under homogeneous conditions when H{sub 2}O was removed from the gas blend. 23 refs., 8 figs.

  4. Removal of organic and inorganic sulfur from Ohio coal by combined physical and chemical process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Attia, Y.A.; Zeky, M.El.; Lei, W.W.; Bavarian, F.; Yu, S. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1989-04-28

    This project consisted of three sections. In the first part, the physical cleaning of Ohio coal by selective flocculation of ultrafine slurry was considered. In the second part, the mild oxidation process for removal of pyritic and organic sulfur.was investigated. Finally, in-the third part, the combined effects of these processes were studied. The physical cleaning and desulfurization of Ohio coal was achieved using selective flocculation of ultrafine coal slurry in conjunction with froth flotation as flocs separation method. The finely disseminated pyrite particles in Ohio coals, in particular Pittsburgh No.8 seam, make it necessary to use ultrafine ({minus}500 mesh) grinding to liberate the pyrite particles. Experiments were performed to identify the ``optimum`` operating conditions for selective flocculation process. The results indicated that the use of a totally hydrophobic flocculant (FR-7A) yielded the lowest levels of mineral matters and total sulfur contents. The use of a selective dispersant (PAAX) increased the rejection of pyritic sulfur further. In addition, different methods of floc separation techniques were tested. It was found that froth flotation system was the most efficient method for separation of small coal flocs.

  5. Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction

    NARCIS (Netherlands)

    Meulepas, R.J.W.

    2009-01-01

    Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal

  6. HYBRID SULFUR RECOVERY PROCESS FOR NATURAL GAS UPGRADING

    International Nuclear Information System (INIS)

    Girish Srinivas; Steven C. Gebhard; David W. DeBerry

    2001-01-01

    This first quarter report of 2001 describes progress on a project funded by the U.S. Department of Energy (DOE) to test a hybrid sulfur recovery process for natural gas upgrading. The process concept represents a low cost option for direct treatment of natural gas streams to remove H(sub 2)S in quantities equivalent to 0.2-25 metric tons (LT) of sulfur per day. This process is projected to have lower capital and operating costs than the competing technologies, amine/aqueous iron liquid redox and amine/Claus/tail gas treating, and have a smaller plant footprint, making it well suited to both on-shore and offshore applications. CrystaSulf(trademark) (service mark of Gas Research Institute) is a new nonaqueous sulfur recovery process that removes hydrogen sulfide (H(sub 2)S) from gas streams and converts it into elemental sulfur. CrystaSulf features high sulfur recovery similar to aqueous-iron liquid redox sulfur recovery processes, but differs from the aqueous processes in that CrystaSulf controls the location where elemental sulfur particles are formed. In the hybrid process, approximately 1/3 of the total H(sub 2)S in the natural gas is first oxidized to SO(sub 2) at low temperatures over a heterogeneous catalyst. Low temperature oxidation is done so that the H(sub 2)S can be oxidized in the presence of methane and other hydrocarbons without oxidation of the hydrocarbons. The project involves the development of a catalyst using laboratory/bench-scale catalyst testing, and then demonstration of the catalyst at CrystaTech's pilot plant in west Texas. During this reporting periods new catalyst formulations were tested. The experiments showed that the newest catalyst has slightly better performance, but catalyst TDA No.2 is still superior overall for use with the hybrid CrystaSulf process due to lower costs. Plans for catalyst pelletization and continued testing are described

  7. Characterization of sludge properties for sewage treatment in a practical-scale down-flow hanging sponge reactor: oxygen consumption and removal of organic matter, ammonium, and sulfur.

    Science.gov (United States)

    Nomoto, Naoki; Hatamoto, Masashi; Ali, Muntjeer; Jayaswal, Komal; Iguchi, Akinori; Okubo, Tsutomu; Takahashi, Masanobu; Kubota, Kengo; Tagawa, Tadashi; Uemura, Shigeki; Yamaguchi, Takashi; Harada, Hideki

    2018-02-01

    The characteristics of sludge retained in a down-flow hanging sponge reactor were investigated to provide a better understanding of the sewage treatment process in the reactor. The organic removal and sulfur oxidation conditions were found to differ between the first layer and the following three layers. It was found that 63% and 59% of the organic matter was removed in the first layer, even though the hydraulic retention time was only 0.2 h. It is thought that the organic removal resulted from aerobic and anaerobic biodegradation on the sponge medium. The sulfate concentration increased 1.5-1.9-fold in the first layer, with almost no subsequent change in the second to fourth layers. It was shown that oxidation of sulfide in the influent was completed in the first layer. The result of the oxygen uptake rate test with an ammonium nitrogen substrate suggested that the ammonium oxidation rate was affected by the condition of dissolved oxygen (DO) or oxidation-reduction potential (ORP).

  8. HYBRID SULFUR RECOVERY PROCESS FOR NATURAL GAS UPGRADING

    International Nuclear Information System (INIS)

    Girish Srinivas; Steven C. Gebhard; David W. DeBerry

    2002-01-01

    This first quarter report of 2002 describes progress on a project funded by the U.S. Department of Energy (DOE) to test a hybrid sulfur recovery process for natural gas upgrading. The process concept represents a low cost option for direct treatment of natural gas streams to remove H(sub 2)S in quantities equivalent to 0.2-25 metric tons (LT) of sulfur per day. This process is projected to have lower capital and operating costs than the competing technologies, amine/aqueous iron liquid redox and amine/Claus/tail gas treating, and have a smaller plant footprint, making it well suited to both on-shore and offshore applications. CrystaSulf(sup SM) (service mark of CrystaTech, Inc.) is a new nonaqueous sulfur recovery process that removes hydrogen sulfide (H(sub 2)S) from gas streams and converts it into elemental sulfur. CrystaSulf features high sulfur recovery similar to aqueous-iron liquid redox sulfur recovery processes, but differs from the aqueous processes in that CrystaSulf controls the location where elemental sulfur particles are formed. In the hybrid process, approximately 1/3 of the total H(sub 2)S in the natural gas is first oxidized to SO(sub 2) at low temperatures over a heterogeneous catalyst. Low temperature oxidation is done so that the H(sub 2)S can be oxidized in the presence of methane and other hydrocarbons without oxidation of the hydrocarbons. The project involves the development of a catalyst using laboratory/bench-scale catalyst testing, and then demonstration of the catalyst at CrystaTech's pilot plant in west Texas. In a previous reporting period tests were done to determine the effect of hydrocarbons such as n-hexane on catalyst performance with and without H(sub 2)S present. The experiments showed that hexane oxidation is suppressed when H(sub 2)S is present. Hexane represents the most reactive of the C1 to C6 series of alkanes. Since hexane exhibits low reactivity under H(sub 2)S oxidation conditions, and more importantly, does not change

  9. Process and system for removing sulfur from sulfur-containing gaseous streams

    Science.gov (United States)

    Basu, Arunabha; Meyer, Howard S.; Lynn, Scott; Leppin, Dennis; Wangerow, James R.

    2012-08-14

    A multi-stage UCSRP process and system for removal of sulfur from a gaseous stream in which the gaseous stream, which contains a first amount of H.sub.2S, is provided to a first stage UCSRP reactor vessel operating in an excess SO.sub.2 mode at a first amount of SO.sub.2, producing an effluent gas having a reduced amount of SO.sub.2, and in which the effluent gas is provided to a second stage UCSRP reactor vessel operating in an excess H.sub.2S mode, producing a product gas having an amount of H.sub.2S less than said first amount of H.sub.2S.

  10. Biologically produced sulfur

    NARCIS (Netherlands)

    Kleinjan, W.E.; Keizer, de A.; Janssen, A.J.H.

    2003-01-01

    Sulfur compound oxidizing bacteria produce sulfur as an intermediate in the oxidation of hydrogen sulfide to sulfate. Sulfur produced by these microorganisms can be stored in sulfur globules, located either inside or outside the cell. Excreted sulfur globules are colloidal particles which are

  11. Facile synthesis of graphene oxide @ mesoporous carbon hybrid nanocomposites for lithium sulfur battery

    International Nuclear Information System (INIS)

    Bao, Weizhai; Zhang, Zhian; Chen, Wei; Zhou, Chengkun; Lai, Yanqing; Li, Jie

    2014-01-01

    Graphical abstract: - Highlights: • A novel design and synthesis of GO@Meso-C using GO@MOF-5 as precursor. • GO@Meso-C hybrid material as a host material was applied for sulfur cathode. • Electrochemical performances were improved in sulfur cathode using Go@Meso-C. - Abstract: We present a design and synthesis of a hierarchical architecture of graphene oxide @ mesoporous carbon (GO@Meso-C) using graphene oxide @ metal-organic framework hybrid materials (GO@MOF-5) as both the template and precursor. Active sulfur is encapsulated into the GO@Meso-C matrix prepared via carbonize GO@MOF-5 polyhedrons for high performance lithium sulfur battery. The initial and 100th cycle discharge capacity of GO@Meso-C/S sulfur cathode are as high as 1122 mAh g −1 and 820 mAh g −1 at a current rate of 0.2 C. The remarkably high special capacity and capacity retention rate indicate that the GO@Meso-C is a promising host material for the sulfur cathode in the lithium sulfur battery applications

  12. Biological removal of sulfur from coal flotation concentrate by culture isolated from coal washery plant tailing dump

    Energy Technology Data Exchange (ETDEWEB)

    Jorjani, E. [Azad University, Tehran (Iran). Mining Engineering Dept.

    2005-10-15

    A combination of flotation and microbial leaching processes was used to achieve acceptable level of sulfur and ash in Tabas coal sample of Iran. Representative sample of the minus 500 micron size fraction was subjected to flotation separation for the removal of ash and sulfur. The final concentrate with recovery, combustion value and sulfur content of 86.03, 86.45 and 1.35% respectively was achieved at pH 8 and following reagent dosage and operating conditions: collector: diesel oil (1200 g/ton), frother: MIBC (5%) + pine oil (95%) with concentration of 120 (g/ton), depressant: sodium silicate (1000 g/ton), particle size: {lt} 500 {mu} m and pulp density: 7%. Because of fine distribution of sulfur on Tabas coal macerals and lithotypes, high percentage of total sulfur (79.9%) is distributed in flotation concentrate and only 20.1% is yielded in the tails. So microbial leaching using a species isolated from coal washery plant tailing dump was used in batch system to remove sulfur from flotation concentrate. The conditions were optimized for the maximum removal of sulfur. These conditions were found to be pH of 2, particle size less than 0.18 mm; pulp density: 8%, temperature: 30 {sup o}C, shaking rate: 150 rpm conditions. Total sulfur and ash content was reduced by bioleaching from 13.55 and 1.35 in flotation concentrate to 9.47 and 0.55 in the final leached concentrate, a reduction of 35 and 61.9% respectively. Sterilization of coal adversely affects the sulfur reduction. The results suggest that the isolated culture is sufficiently effective for depyritization of Tabas coal flotation concentrate in stirred system.

  13. Ultrasound-assisted oxidative desulfurization of bunker-C oil using tert-butyl hydroperoxide.

    Science.gov (United States)

    Tang, Qiong; Lin, Song; Cheng, Ying; Liu, Sujun; Xiong, Jun-Ru

    2013-09-01

    This work investigated the ultrasonic assisted oxidative desulfurization of bunker-C oil with TBHP/MoO3 system. The operational parameters for the desulfurization procedure such as ultrasonic irradiation time, ultrasonic wave amplitude, catalyst initial concentration and oxidation agent initial concentration were studied. The experimental results show that the present oxidation system was very efficient for the desulfurization of bunker-C oil and ~35% sulfur was removed which was dependent on operational parameters. The application of ultrasonic irradiation allowed sulfur removal in a shorter time. The stronger the solvent polarity is, the higher the sulfur removal rate, but the recovery rate of oil is lower. The sulfur compounds in bunker-C oil reacted with TBHP to produce corresponding sulfoxide, and further oxidation produced the corresponding sulfone. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Desulfurization of Diesel Fuel by Oxidation and Solvent Extraction

    Directory of Open Access Journals (Sweden)

    Wadood Taher Mohammed

    2015-02-01

    Full Text Available This research presents a study in ultra-desulfurization of diesel fuel produced from conventional hydro desulfurization process, using oxidation and solvent extraction techniques. Dibenzothiophene (DBT was the organosulfur compound that had been detected in sulfur removal. The oxidation process used hydrogen peroxide as an oxidant and acetic acid as homogeneous catalyst . The solvent extraction process used acetonitrile (ACN and N-methyl – 2 - pyrrolidone (NMP as extractants . Also the effect of five parameters (stirring speed :150 , 250 , 350 , and 450 rpm, temperature (30 , 40 , 45 , and 50 oC, oxidant/simulated diesel fuel ratio (0.5 , 0.75 , 1 , and 1.5 , catalyst/oxidant ratio(0.125,0.25,0.5,and0.75 , and solvent/simulated diesel fuel ratio(0.5,0.6,0.75,and1 were examined as well as solvent type. The results exhibit that the highest removal of sulfur is 98.5% using NMP solvent while it is 95.8% for ACN solvent. The set of conditions that show the highest sulfur removal is: stirring speed of 350 rpm , temperature 50oC , oxidant/simulated diesel fuel ratio 1 , catalyst/oxidant ratio 0.5 , solvent/simulated diesel fuel ratio 1. These best conditions were applied upon real diesel fuel (produced from Al-Dora refinerywith 1000 ppm sulfur content . It was found that sulfur removal was 64.4% using ACN solvent and 75% using NMP solvent.

  15. 40 CFR 52.1126 - Control strategy: Sulfur oxides.

    Science.gov (United States)

    2010-07-01

    ... Department of Environmental Quality Engineering.). Gardner State Hospital, Gardner. Grafton State Hospital... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Sulfur oxides. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1126 Control...

  16. The role of sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering

    International Nuclear Information System (INIS)

    Sasaki, K.; Tsunekawa, M.; Ohtsuka, T.; Konno, H.

    1998-01-01

    The paper investigates the role of the sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering in order to clarify the effects of the bacteria on the dissolution behavior of pyrite and the formation of secondary minerals using Raman spectroscopy and powder X-ray diffraction (XRD) in addition to solution analysis. It was found that T. thiooxidans, when present with the iron-oxidizing bacteria Thiobacillus ferrooxidans, enhanced the dissolution of Fe and S species for pyrite, whereas T. thiooxidans alone did not oxidize pyrite. Enhancement of the consumption of elemental sulfur and regeneration of Fe(II) ions were also observed with T. thiooxidans together with T. ferrooxidans, while this did not occur with T. ferrooxidans alone

  17. Removal of sulfur from process streams

    International Nuclear Information System (INIS)

    Brignac, D.G.

    1984-01-01

    A process wherein water is added to a non-reactive gas stream, preferably a hydrogen or hydrogen-containing gas stream, sufficient to raise the water level thereof to from about 0.2 percent to about 50 percent, based on the total volume of the process gas stream, and the said moist gas stream is contacted, at elevated temperature, with a particulate mass of a sulfur-bearing metal alumina spinel characterized by the formula MAl 2 O 4 , wherein M is chromium, iron, cobalt, nickel, copper, cadmium, mercury, or zinc to desorb sulfur thereon. In the sulfur sorption cycle, due to the simultaneous adsorption of water and sulfur, the useful life of the metal alumina spinel for sulfur adsorption can be extended, and the sorbent made more easily regenerable after contact with a sulfur-bearing gas stream, notably sulfur-bearing wet hydrogen or wet hydrogen-rich gas streams

  18. Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid

    Directory of Open Access Journals (Sweden)

    Alireza Haghighat Mamaghani

    2013-01-01

    Full Text Available An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was followed by a liquid-liquid extraction stage using acetonitrile as a polar solvent to remove produced sulfones from the model fuel. The impact of operating parameters including the molar ratio of formic acid to sulfur (, hydrogen peroxide to sulfur (, and the time of reaction was investigated using Box-Behnken experimental design for oxidation of the model fuel. A significant quadratic model was introduced for the sulfur removal as a function of effective parameters by the statistic analysis.

  19. Improvement of sulfur resistance of Pd/Ce-Zr-Al-O catalysts for CO oxidation

    Science.gov (United States)

    Shin, Haebin; Baek, Minsung; Ro, Youngsoo; Song, Changyeol; Lee, Kwan-Young; Song, In Kyu

    2018-01-01

    Two kinds of mesoporous ceria-zirconia-alumina supports were prepared by a single-step epoxide-driven sol-gel method (SGCZA) and by a co-precipitation method (PCZA). Palladium catalysts supported on these materials were then prepared by a wet impregnation method (Pd/SGCZA and Pd/PCZA). The prepared catalysts were applied to the CO oxidation reaction before and after sulfur aging. XRD and N2 adsorption-desorption analyses revealed that these two catalysts retained different physicochemical properties. Pd/SGCZA had higher surface area and larger pore volume than Pd/PCZA before and after sulfur aging. TPR (Temperature-programmed reduction), CO chemisorption, FT-IR, and XPS analyses showed that the catalysts were differently influenced by sulfur species. Pd/SGCZA formed less sulfate and retained higher palladium dispersion than Pd/PCZA after sulfur aging. In the CO oxidation, Pd/PCZA showed better activity than Pd/SGCZA before sulfur aging. However, Pd/SGCZA showed higher CO conversion than Pd/PCZA after sulfur aging. We concluded that Pd/SGCZA was less poisoned by sulfur species than Pd/PCZA.

  20. EFFECT OF SOLE AND ASSOCIATIVE ACTIONS OF ELEMENTAL SULFUR AND INOCULATION SULFUR OXIDIZING BACTERIA ON GROWTH AND NUTRIENTS CONTENTS OF PEPPER PLANTS AND THE USED SOILS

    Directory of Open Access Journals (Sweden)

    S. A. Ibrahim

    2011-12-01

    Full Text Available A pot experiment was conducted to study the effect of elemental sulfur (E.S rate (2.5 g/kg soil and sulfur oxidizing bacteria on pepper plant and some chemical properties of two representative soil samples varying in their texture and CaCO3 content. Pepper was grown in Shobrakheet clay loam and Nobaria sandy loam soils for 50 days. Each soil was treated with elemental sulfur (2.5 g kg-1 soil and inoculated with two sulfur oxidizing bacteria (S.O.B. No.8 and S.O.B. ATCC 8158. Elemental sulfur with or without sulfur oxidizing bacteria increased shoot dry weights of pepper plants as compared with control. The highest effect was observed with E.S + ATCC 8158 treatment which resulted in increasing the pepper shoot dry weights from 1.36 to 2.08 g pot-1 with the clay loam soil and from 0.77 to 1.37 g pot-1 with the sandy loam soil. The same treatment resulted in the highest plant content of S, N, P, K and micronutrients.

  1. Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

    International Nuclear Information System (INIS)

    Praveen Kumar, J.; Prasad, G.K.; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

    2013-01-01

    Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m 2 g −1 when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions

  2. Mesoporous CuO–ZnO binary metal oxide nanocomposite for decontamination of sulfur mustard

    Energy Technology Data Exchange (ETDEWEB)

    Praveen Kumar, J.; Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Garg, P.; Ganesan, K.

    2013-11-01

    Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. They were prepared by precipitation pyrolysis method and characterized by means of X-ray diffraction, transmission electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy techniques. Obtained data indicated the presence of mesopores with diameter ranging from 2 to 80 nm and the materials exhibited relatively high surface area 86 m{sup 2} g{sup −1} when compared to the individual metal oxide nanoparticles. Reactive sites of mesoporous CuO–ZnO binary metal oxide nanocomposites were studied by infrared spectroscopy technique using pyridine as a probe molecule. These materials demonstrated superior decontamination properties against sulfur mustard when compared to single component metal oxides and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Graphical abstract: Mesoporous CuO–ZnO binary metal oxide nanocomposites were studied as sorbent decontaminants against sulfur mustard, a well known chemical warfare agent. These materials demonstrated superior decontamination properties against sulfur mustard and decontaminated it to divinyl sulfide, chloroethyl vinyl sulfide, hemisulfur mustard, etc. - Highlights: • Preparation of mesoporous CuO–ZnO binary metal oxide nanocomposite. • CuO–ZnO with better surface area was synthesized by precipitation pyrolysis. • Decontamination of HD using mesoporous CuO–ZnO binary metal oxide nanocomposite. • HD decontaminated by elimination and hydrolysis reactions.

  3. Regulation of dsr genes encoding proteins responsible for the oxidation of stored sulfur in Allochromatium vinosum.

    Science.gov (United States)

    Grimm, Frauke; Dobler, Nadine; Dahl, Christiane

    2010-03-01

    Sulfur globules are formed as obligatory intermediates during the oxidation of reduced sulfur compounds in many environmentally important photo- and chemolithoautotrophic bacteria. It is well established that the so-called Dsr proteins are essential for the oxidation of zero-valent sulfur accumulated in the globules; however, hardly anything is known about the regulation of dsr gene expression. Here, we present a closer look at the regulation of the dsr genes in the phototrophic sulfur bacterium Allochromatium vinosum. The dsr genes are expressed in a reduced sulfur compound-dependent manner and neither sulfite, the product of the reverse-acting dissimilatory sulfite reductase DsrAB, nor the alternative electron donor malate inhibit the gene expression. Moreover, we show the oxidation of sulfur to sulfite to be the rate-limiting step in the oxidation of sulfur to sulfate as sulfate production starts concomitantly with the upregulation of the expression of the dsr genes. Real-time RT-PCR experiments suggest that the genes dsrC and dsrS are additionally expressed from secondary internal promoters, pointing to a special function of the encoded proteins. Earlier structural analyses indicated the presence of a helix-turn-helix (HTH)-like motif in DsrC. We therefore assessed the DNA-binding capability of the protein and provide evidence for a possible regulatory function of DsrC.

  4. Balancing surface adsorption and diffusion of lithium-polysulfides on nonconductive oxides for lithium-sulfur battery design.

    Science.gov (United States)

    Tao, Xinyong; Wang, Jianguo; Liu, Chong; Wang, Haotian; Yao, Hongbin; Zheng, Guangyuan; Seh, Zhi Wei; Cai, Qiuxia; Li, Weiyang; Zhou, Guangmin; Zu, Chenxi; Cui, Yi

    2016-04-05

    Lithium-sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.

  5. Balancing surface adsorption and diffusion of lithium-polysulfides on nonconductive oxides for lithium–sulfur battery design

    Science.gov (United States)

    Tao, Xinyong; Wang, Jianguo; Liu, Chong; Wang, Haotian; Yao, Hongbin; Zheng, Guangyuan; Seh, Zhi Wei; Cai, Qiuxia; Li, Weiyang; Zhou, Guangmin; Zu, Chenxi; Cui, Yi

    2016-01-01

    Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides. PMID:27046216

  6. Removal of sulfur dioxide and formation of sulfate aerosol in Tokyo

    Science.gov (United States)

    Miyakawa, T.; Takegawa, N.; Kondo, Y.

    2007-07-01

    Ground-based in situ measurements of sulfur dioxide (SO2) and submicron sulfate aerosol (SO42-) together with carbon monoxide (CO) were conducted at an urban site in Tokyo, Japan from spring 2003 to winter 2004. The observed concentrations of SO2 were affected dominantly by anthropogenic emissions (for example, manufacturing industries) in source areas, while small fraction of the data (sulfur compounds (SOx = SO2 + SO42-) and the remaining fraction of SOx, which is derived as the ratio of the linear regression slope of the SOx-CO correlation, is used as measures for the formation of SO42- and removal of SOx, respectively. Using these parameters, the average formation efficiency of SO42- (i.e., amount of SO42- produced per SO2 emitted from emission sources) are estimated to be 0.18 and 0.03 in the summer and winter periods, respectively. A simple box model was developed to estimate the lifetime of SOx. The lifetime of SOx for the summer period (26 h) is estimated to be about two times longer than that for the winter period (14 h). The seasonal variations of the remaining fraction of SOx, estimated formation efficiency of SO42-, and lifetime of SOx are likely due to those of the boundary layer height and photochemical activity (i.e., hydroxyl radical). These results provide useful insights into the formation and removal processes of sulfur compounds exported from an urban area.

  7. Measurement of sulfur dioxide oxidation rates in wintertime orographic clouds

    International Nuclear Information System (INIS)

    Snider, J.R.

    1990-01-01

    SO2-reaction studies in the clouds are examined and summarized to experimentally confirm model predictions and previous field studies regarding dominant SO2-reaction pathways. Controlled amounts of SO2 were released into nonprecipitating orographic clouds, and sulfate yields are compared to oxidant depletions. The sulfate yields were taken from cloud-water samples and liquid-water-concentration measurements, and oxidant-depletion data were generated from continuous gas-phase measurements. Comparisons of Y sub SO4 and D sub H2O2 suggest that H2O2 is the dominant oxidant, and the in-cloud reaction between H2O2 and the bisulfite ion can be expressed by a simple rate that agrees with predictions and laboratory results. The rate measurements are found to be inconsistent with the rate law proposed by Hegg and Hobbs (1982) and with some observational data. The present conclusions are of interest to evaluating the effects of sulfur dioxide emissions on sulfuric acid deposition. 30 refs

  8. Synthesis of a Flexible Freestanding Sulfur/Polyacrylonitrile/Graphene Oxide as the Cathode for Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    Huifen Peng

    2018-04-01

    Full Text Available Rechargeable lithium/sulfur (Li/S batteries have received quite significant attention over the years because of their high theoretical specific capacity (1672 mAh·g−1 and energy density (2600 mAh·g−1 which has led to more efforts for improvement in their electrochemical performance. Herein, the synthesis of a flexible freestanding sulfur/polyacrylonitrile/graphene oxide (S/PAN/GO as the cathode for Li/S batteries by simple method via vacuum filtration is reported. The S/PAN/GO hybrid binder-free electrode is considered as one of the most promising cathodes for Li/S batteries. Graphene oxide (GO slice structure provides effective ion conductivity channels and increases structural stability of the ternary system, resulting in excellent electrochemical properties of the freestanding S/PAN/GO cathode. Additionally, graphene oxide (GO membrane was able to minimize the polysulfides’ dissolution and their shuttle, which was attributed to the electrostatic interactions between the negatively-charged species and the oxygen functional groups on GO. Furthermore, these oxygen-containing functional groups including carboxyl, epoxide and hydroxyl groups provide active sites for coordination with inorganic materials (such as sulfur. It exhibits the initial reversible specific capacity of 1379 mAh·g−1 at a constant current rate of 0.2 C and maintains 1205 mAh·g−1 over 100 cycles (~87% retention. In addition, the freestanding S/PAN/GO cathode displays excellent coulombic efficiency (~100% and rate capability, delivering up to 685 mAh·g−1 capacity at 2 C.

  9. Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

    Science.gov (United States)

    Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

    2015-01-01

    We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

  10. New insight of high temperature oxidation on self-exfoliation capability of graphene oxide

    Science.gov (United States)

    Liu, Yuhang; Zeng, Jie; Han, Di; Wu, Kai; Yu, Bowen; Chai, Songgang; Chen, Feng; Fu, Qiang

    2018-05-01

    The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

  11. Anthropogenic emissions of oxidized sulfur and nitrogen into the atmosphere of the former Soviet Union in 1985 and 1990

    Energy Technology Data Exchange (ETDEWEB)

    Ryaboshapko, A.G.; Brukhanov, P.A.; Gromov, S.A.; Proshina, Yu.V; Afinogenova, O.G. [Institute of Global Climate and Ecology, Moscow (Russian Federation)

    1996-09-01

    Anthropogenic emissions of oxidized sulfur and nitrogen over the former Soviet Union for 1985 and 1990 were calculated on the basis of a combination of `bottom-up` and `top-down` approaches. Sulfur dioxide emissions from combustion of hard coal, brown coal, oil products, natural gas, shale oil, peat, wood as well as from metallurgy, sulfuric acid production, and cement production were estimated. Nitrogen oxides emissions were considered separately for large power plants, small power plants, industrial boilers, residential combustion units, and for transport. The sulfur and nitrogen emissions were spatially distributed over the former Soviet Union with 1 x 1 degree resolution. Data on 721 point sources of sulfur dioxide emissions and on the 242 largest power stations as nitrogen oxides sources were used. The area sources of both sulfur dioxide and nitrogen oxides were distributed according to the population density separately for about 150 administrative units of the former Soviet Union. 63 refs., 19 tabs.

  12. Composition and oxidation state of sulfur in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    A. F. Longo

    2016-10-01

    Full Text Available The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS and X-ray fluorescence (XRF microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  13. Removal of ethylene oxide from waste gases by absorption

    Directory of Open Access Journals (Sweden)

    Arsenijević Zorana Lj.

    2011-01-01

    Full Text Available Ethylene oxide (EtO is an organic compound, which is used as starting material in the production of polymers and as sterilizing agent for thermolabile materials. Although ethylene oxide is not common as an organic pollutant, its removal from numerous emission sources (e.g. ethylene oxide production plants or food and pharmaceutical sterilizing units is of the crucial importance because of its mutagenic, teratogenic and cancerogenic effect on human health. The objective of this paper is the experimental investigation of ethylene oxide (EtO absorption in diluted aqueous solution of sulfuric acid in order to evaluate the applicability of this procedure as well as to obtain project parameters for industrial plant realization. It was found that absorption is suitable as the fist step in the purification treatment of high EtO concentrations in the emission gases. According to the literature data, the basic parameter that defines the scrubber efficiency is the contact time, i.e. the ratio of packing height in scrubber and velocity of gas mixture. To investigate the characteristics of wet treatment in a broad range of contact time, part of experimental studies were conducted in the system with two and with three scrubbers in series. The obtained experimental results show that the high degree of EtO removal can be achieved (>98% when the contact time is sufficiently long (about 25 s. The process is effective until the concentration of formed glycol in the solution reaches value of about 20%. The process is safe and there is no danger of ignition and explosion of air and EtO mixture, although at the entrance to the scrubber EtO concentrations are significantly above the lower explosive limit.

  14. Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid

    OpenAIRE

    Haghighat Mamaghani, Alireza; Fatemi, Shohreh; Asgari, Mehrdad

    2013-01-01

    An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was ...

  15. Intensification of oxidative desulfurization of gas oil by ultrasound irradiation: Optimization using Box–Behnken design (BBD)

    International Nuclear Information System (INIS)

    Jalali, Mohammad Reza; Sobati, Mohammad Amin

    2017-01-01

    Highlights: • Ultrasound-assisted oxidative desulfurization (UAOD) of gas oil was studied. • The influences of the different operating parameters were investigated. • Response surface methodology (RSM) was used to find the best operating parameters. • An accurate correlation was developed for the sulfur removal. • Ultrasound-assisted desulfurization process was compared with conventional process. - Abstract: In the present work, ultrasound assisted oxidative desulfurization (UAOD) of gas oil as the feedstock with sulfur content of 2210 ppmw was investigated using a mixture of hydrogen peroxide and formic acid as the oxidant and catalyst, respectively. The influences of main process variables such as sonication time (2–30 min), oxidation temperature (40–70 °C), hydrogen peroxide to sulfur molar ratio (10–50), formic acid to oxidant molar ratio (2–4), ultrasound power per gas oil volume (5.56–8.89 W/mL), and number of extraction stages (1–4) on the sulfur removal of gas oil were investigated. Response surface methodology (RSM) based on Box–Behnken design (BBD) and single-factor experiments were employed. The best performance of UAOD process for gas oil was achieved at 50 °C of reaction temperature, oxidant to sulfur molar ratio of 46.36, formic acid to oxidant molar ratio of 3.22, sonication time of 19.81 min, and 7.78 W/mL as the ultrasound power per gas oil volume. The sulfur removal of UAOD process was evaluated after oxidation under the abovementioned conditions followed by (a) one stage extraction and (b) four stages extraction using acetonitrile as solvent. The observed sulfur removal was 87 for case (a) and 96.2% for case (b). The UAOD process was also compared with conventional ODS process. Considerable improvement on the sulfur removal was observed specially in lower reaction time in the case of using ultrasound irradiation in comparison with conventional mixing.

  16. Mathematical modelling of the kinetics of aerosol oxidation of sulfur dioxide upon electron-beam purification of power-plant flue gases from nitrogen and sulfur oxides

    International Nuclear Information System (INIS)

    Gerasimov, G.Ya.; Gerasimova, T.S.; Fadeev, S.A.

    1996-01-01

    A kinetic model of SO 2 oxidation in flue gases, irradiated with accelerated electron flux is proposed. The model comprises an optimized mechanism of gas phase radiation chemical oxidation of NO and SO 2 , kinetics circuit of SO 2 and NH 3 thermal interaction, kinetic models of volumetric condensation of water and sulfuric acid vapors and liquid-phase oxidation of SO 2 in aerosol drops, produced in the course of volumetric condensation. Calculation results are in a satisfactory agreement with experimental data. (author)

  17. Deep desulfurization of diesel via peroxide oxidation using phosphotungstic acid as phase transfer catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sachdeva, T.O.; Pant, K.K. [Department of Chemical Engineering, Indian Institute of Technology, Delhi, New Delhi, 110016 (India)

    2010-09-15

    High sulfur level in diesel fuel has been identified as a major contributor to air pollutant in term of sulfur dioxide (SO{sub x}) through diesel fueled vehicles. The main aim of the present work is to develop a promising methodology for ultra deep desulfurization of diesel fuel using oxidation followed by phase transfer of oxidized sulfur. Experiments were carried out in a batch reactor using n-decane as the model diesel compound and also using commercial diesel feedstock. To remove sulfur tetraoctylammonium bromide, phosphotungstic acid, and hydrogen peroxide were used as phase transfer agent, catalyst and oxidant respectively. The percent sulfur removal increases with increasing the initial concentration of sulfur in fuel and with increasing the reaction temperature. Similar trends were observed when commercial diesel was used to carry out desulfurization studies. The amphiphilic catalyst serves as a catalyst and also as an emulsifying agent to stabilize the emulsion droplets. The effects of temperature, agitation speed, quantity of catalyst and the phase transfer agent were studied to estimate the optimal conditions for the reactions. The sulfur removal from a commercial diesel by phase transfer catalysis has been found effective and removal efficiency was more than 98%. Kinetic experiments carried out for the desulfurization revealed that the sulfur removal results are best fitted to a pseudo first order kinetics and the apparent activation energy of desulfurization was 30.6 kJ/mol. (author)

  18. Deep desulfurization of diesel via peroxide oxidation using phosphotungstic acid as phase transfer catalyst

    International Nuclear Information System (INIS)

    Sachdeva, T.O.; Pant, K.K.

    2010-01-01

    High sulfur level in diesel fuel has been identified as a major contributor to air pollutant in term of sulfur dioxide (SO x ) through diesel fueled vehicles. The main aim of the present work is to develop a promising methodology for ultra deep desulfurization of diesel fuel using oxidation followed by phase transfer of oxidized sulfur. Experiments were carried out in a batch reactor using n-decane as the model diesel compound and also using commercial diesel feedstock. To remove sulfur tetraoctylammonium bromide, phosphotungstic acid, and hydrogen peroxide were used as phase transfer agent, catalyst and oxidant respectively. The percent sulfur removal increases with increasing the initial concentration of sulfur in fuel and with increasing the reaction temperature. Similar trends were observed when commercial diesel was used to carry out desulfurization studies. The amphiphilic catalyst serves as a catalyst and also as an emulsifying agent to stabilize the emulsion droplets. The effects of temperature, agitation speed, quantity of catalyst and the phase transfer agent were studied to estimate the optimal conditions for the reactions. The sulfur removal from a commercial diesel by phase transfer catalysis has been found effective and removal efficiency was more than 98%. Kinetic experiments carried out for the desulfurization revealed that the sulfur removal results are best fitted to a pseudo first order kinetics and the apparent activation energy of desulfurization was 30.6 kJ/mol. (author)

  19. Oxygen and sulfur isotope systematics of sulfate produced during abiotic and bacterial oxidation of sphalerite and elemental sulfur

    Science.gov (United States)

    Balci, N.; Mayer, B.; Shanks, Wayne C.; Mandernack, K.W.

    2012-01-01

    Studies of metal sulfide oxidation in acid mine drainage (AMD) systems have primarily focused on pyrite oxidation, although acid soluble sulfides (e.g., ZnS) are predominantly responsible for the release of toxic metals. We conducted a series of biological and abiotic laboratory oxidation experiments with pure and Fe-bearing sphalerite (ZnS & Zn 0.88Fe 0.12S), respectively, in order to better understand the effects of sulfide mineralogy and associated biogeochemical controls of oxidation on the resultant ?? 34S and ?? 18O values of the sulfate produced. The minerals were incubated in the presence and absence of Acidithiobacillus ferrooxidans at an initial solution pH of 3 and with water of varying ?? 18O values to determine the relative contributions of H 2O-derived and O 2-derived oxygen in the newly formed sulfate. Experiments were conducted under aerobic and anaerobic conditions using O 2 and Fe(III) aq as the oxidants, respectively. Aerobic incubations with A. ferrooxidans, and S o as the sole energy source were also conducted. The ??34SSO4 values from both the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq produced sulfur isotope fractionations (??34SSO4-ZnS) of up to -2.6???, suggesting the accumulation of sulfur intermediates during incomplete oxidation of the sulfide. No significant sulfur isotope fractionation was observed from any of the aerobic experiments. Negative sulfur isotope enrichment factors (??34SSO4-ZnS) in AMD systems could reflect anaerobic, rather than aerobic pathways of oxidation. During the biological and abiotic oxidation of ZnS and ZnS Fe by Fe(III) aq all of the sulfate oxygen was derived from water, with measured ?? 18OSO 4-H 2O values of 8.2??0.2??? and 7.5??0.1???, respectively. Also, during the aerobic oxidation of ZnS Fe and S o by A. ferrooxidans, all of the sulfate oxygen was derived from water with similar measured ?? 18OSO 4-H 2O values of 8.1??0.1??? and 8.3??0.3???, respectively. During biological oxidation

  20. Photoactive thin film semiconducting iron pyrite prepared by sulfurization of iron oxides

    Energy Technology Data Exchange (ETDEWEB)

    Smestad, G.; Ennaoui, A.; Fiechter, S.; Tributsch, H.; Hofmann, W.K.; Birkholz, M. (Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.). Abt. Solare Energetik Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.). Abt. Materialforschung); Kautek, W. (Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany, F.R.))

    1990-03-01

    Photoactive iron pyrite (FeS{sub 2}) thin film layers have been synthesized by a simple method involving the reaction of Fe{sub 3}O{sub 4} or Fe{sub 2}O{sub 3} with elemental sulfur. The films were formed on a variety of different substrate materials by converting or sulfurizing iron oxide layers. The subsequent sulfur treatment of the oxide layers consisted of exposure of the films to gaseous sulfur in open or closed ampules at 350degC for 0.5-2 h. The morphology, composition and photoactivity of the films produced were checked using X-ray diffraction, X-ray photoelectron spectroscopy (ESCA), optical absorption, steady state and transient photoconductivity. The best films showed good crystallinity and purity with concurrent photoconductivity and photoelectrochemical response. The ability of this technique to produce photoactive material can be explained by interpretation of the Gibbs ternary phase diagram for the Fe-O-S system, and may be related to the production of photoactive pyrite in nature. A discussion is made as to the future improvement of the solar cell response by proper optimization of geometric and configurational properties. (orig.).

  1. Arsenic Removal from Water Using Various Adsorbents: Magnetic Ion Exchange Resins, Hydrous Ion Oxide Particles, Granular Ferric Hydroxide, Activated Alumina, Sulfur Modified Iron, and Iron Oxide-Coated Microsand

    KAUST Repository

    Sinha, Shahnawaz

    2011-09-30

    The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four natural types (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxide particles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated mic - rosand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The results showed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determined for a given equilibrium concentration of C eq = 10 μg/L were 500 mg/L for AA and GFH, 520–1,300 mg/L for MIEX, 1,200 mg/L for HIOPs, 2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbents were 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantly reduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenic in the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbents had lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreased by approximately 60–95 % .

  2. Application of acoustic agglomeration for removing sulfuric acid mist from air stream

    Directory of Open Access Journals (Sweden)

    Asghar Sadighzadeh

    2018-01-01

    Full Text Available The application of acoustic fields at high sound pressure levels (SPLs for removing sulfuric acid mists from the air stream was studied. An acoustic agglomeration chamber was used to conduct the experiments. The studied SPLs ranged from 115 to 165 decibel (dB, with three inlet concentrations of acid mist at 5–10, 15–20, and 25–30 ppm. The air flow rates for conducting experiments were 20, 30, and 40 L min−1. The concentration of sulfuric acid mist was measured using US Environmental Protection Agency Method 8 at inlet and outlet of the chamber. The resonance frequencies for experiments were found to be 852, 1410, and 3530 Hz. The maximum acoustic agglomeration efficiency of 86% was obtained at optimum frequency of 852 Hz. The analysis of variance test revealed significant differences between agglomeration efficiency at three resonance frequencies (p-value < 0.001. The maximum acoustic agglomeration efficiency was obtained at SPL level of 165 dB. High initial concentrations of acid mists and lower air flow rates enhance the acoustic agglomeration of mists. High removal efficiency of acid mists from air stream could be achieved by the application of acoustic agglomeration method with appropriate range of frequencies and SPLs. Keywords: Sulfuric acid, Mist, Acoustic agglomeration, SPL

  3. Characterization of sulfur-oxidizing bacteria isolated from acid mine drainage and black shale samples

    International Nuclear Information System (INIS)

    Sajjad, W.; Bhatti, T. M.; Hasan, F.; Khan, S.; Badshah, M.

    2016-01-01

    Acid mine drainage (AMD) and black shale (BS) are the main habitats of sulfur-oxidizing bacteria. The aim of this study was to isolate and characterize sulfur-oxidizing bacteria from extreme acidic habitats (AMD and BS). Concentration of metals in samples from AMD and BS varied significantly from the reference samples and exceeded the acceptable limits set by the Environmental Protection Agency (EPA) and the World Health Organization (WHO). A total of 24 bacteria were isolated from these samples that were characterized both morphologically as well as through biochemical tests. All the bacteria were gram-negative rods that could efficiently oxidize sulfur into sulfate ions (SO/sub 4/-2), resulted into decrease in pH up to 1.0 when grown in thiosulfate medium with initial pH 4.0. Out of 24, only 06 isolates were selected for phylogenetic analysis through 16S rRNA sequencing, on the basis of maximum sulfur-oxidizing efficiency. The isolates were identified as the species from different genera such as Alcaligenes, Pseudomonas, Bordetella, and Stenotrophomonas on the basis of maximum similarity index. The concentration of sulfate ions produced was estimated in the range of 179-272 mg/L. These acidophiles might have various potential applications such as biological leaching of metals from low-grade ores, alkali soil reclamation and to minimize the use of chemical S-fertilizers and minimize environmental pollution. (author)

  4. Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

    Science.gov (United States)

    Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

    2016-04-27

    Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

  5. Oxidation of refractory sulfur compounds over Ti-containing mesoporous molecular sieves prepared by using a fluorosilicon compound.

    Science.gov (United States)

    Jeong, Kwang-Eun; Cho, Chin-Soo; Chae, Ho-Jeong; Kim, Chul-Ung; Jeong, Soon-Yong

    2010-05-01

    Titanium containing mesoporous molecular sieve (Ti-MMS) catalysts were studied for the oxidative desulfurization of refractory sulfur compounds. Ti-MMS catalysts were synthesized from fluorosilicon compounds and Ti with the hydrolysis reaction of H2SiF6 in an ammonia-surfactant mixed solution. The solid products were characterized by XRD, XRF, nitrogen adsorption, and diffuse reflectance UV-vis spectroscopy. Effects of Ti loading and oxidant/sulfur mole ratio, and sulfur species on ODS activity were investigated.

  6. The influence of water vapor and sulfur dioxide on the catalytic decomposition of nitrous oxide

    Energy Technology Data Exchange (ETDEWEB)

    Yalamas, C.; Heinisch, R.; Barz, M. [Technische Univ. Berlin (Germany). Inst. fuer Energietechnik; Cournil, M. [Ecole Nationale Superieure des Mines, 42 - Saint-Etienne (France)

    2001-03-01

    For the nitrous oxide decomposition three groups of catalysts such as metals on support, hydrotalcites, and perovskites were studied relating to their activity in the presence of vapor or sulfur dioxide, in the temperature range from 200 to 500 C. It was found that the water vapor strongly inhibates the nitrous oxide decomposition at T=200-400 C. The sulfur dioxide poisons the catalysts, in particular the perovskites. (orig.)

  7. Sulfur rich microporous polymer enables rapid and efficient removal of mercury(II) from water.

    Science.gov (United States)

    Xu, Dan; Wu, Winston Duo; Qi, Hao-Jun; Yang, Rui-Xia; Deng, Wei-Qiao

    2018-04-01

    Design and synthesis of adsorbents for efficient decontamination of hazardous contaminants Hg 2+ from wastewater, based on a facile and economical strategy, is an attractive target. Here, a novel sulfur rich microporous polymer (sulfur content of 31.4 wt %) with high surface area as well as densely populated sulfur atom with fast accessibility was reported to remove mercury (II) from water. The as prepared polymer (SMP) exhibited high binding affinity, high adsorption capacities, rapid adsorption kinetics, and good recyclability for Hg 2+ . The adsorption capacity of SMP was 595.2 mg g -1 . Furthermore, SMP could reduce trace concentrations of Hg 2+ from 200 p. p. b. to a level below drinking water standards (2 p. p. b.) within 3 min. This work allows large-scale production of sulfur rich porous materials for the practical application in water treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Near-Zero Emissions Oxy-Combustion Flue Gas Purification Task 2: SOx/Nox/Hg Removal for High Sulfur Coal

    Energy Technology Data Exchange (ETDEWEB)

    Nick Degenstein; Minish Shah; Doughlas Louie

    2012-05-01

    The goal of this project is to develop a near-zero emissions flue gas purification technology for existing PC (pulverized coal) power plants that are retrofitted with oxy-combustion technology. The objective of Task 2 of this project was to evaluate an alternative method of SOx, NOx and Hg removal from flue gas produced by burning high sulfur coal in oxy-combustion power plants. The goal of the program was not only to investigate a new method of flue gas purification but also to produce useful acid byproduct streams as an alternative to using a traditional FGD and SCR for flue gas processing. During the project two main constraints were identified that limit the ability of the process to achieve project goals. 1) Due to boiler island corrosion issues >60% of the sulfur must be removed in the boiler island with the use of an FGD. 2) A suitable method could not be found to remove NOx from the concentrated sulfuric acid product, which limits sale-ability of the acid, as well as the NOx removal efficiency of the process. Given the complexity and safety issues inherent in the cycle it is concluded that the acid product would not be directly saleable and, in this case, other flue gas purification schemes are better suited for SOx/NOx/Hg control when burning high sulfur coal, e.g. this project's Task 3 process or a traditional FGD and SCR.

  9. A Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) process for decentralized wastewater treatment.

    Science.gov (United States)

    Krayzelova, Lucie; Lynn, Thomas J; Banihani, Qais; Bartacek, Jan; Jenicek, Pavel; Ergas, Sarina J

    2014-09-15

    Nitrogen discharges from decentralized wastewater treatment (DWT) systems contribute to surface and groundwater contamination. However, the high variability in loading rates, long idle periods and lack of regular maintenance presents a challenge for biological nitrogen removal in DWT. A Tire-Sulfur Hybrid Adsorption Denitrification (T-SHAD) process was developed that combines nitrate (NO3(-)) adsorption to scrap tire chips with sulfur-oxidizing denitrification. This allows the tire chips to adsorb NO3(-) when the influent loading exceeds the denitrification capacity of the biofilm and release it when NO3(-) loading rates are low (e.g. at night). Three waste products, scrap tire chips, elemental sulfur pellets and crushed oyster shells, were used as a medium in adsorption, leaching, microcosm and up-flow packed bed bioreactor studies of NO3(-) removal from synthetic nitrified DWT wastewater. Adsorption isotherms showed that scrap tire chips have an adsorption capacity of 0.66 g NO3(-)-N kg(-1) of scrap tires. Leaching and microcosm studies showed that scrap tires leach bioavailable organic carbon that can support mixotrophic metabolism, resulting in lower effluent SO4(2-) concentrations than sulfur oxidizing denitrification alone. In column studies, the T-SHAD process achieved high NO3(-)-N removal efficiencies under steady state (90%), variable flow (89%) and variable concentration (94%) conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Interface polymerization synthesis of conductive polymer/graphite oxide@sulfur composites for high-rate lithium-sulfur batteries

    International Nuclear Information System (INIS)

    Wang, Xiwen; Zhang, Zhian; Yan, Xiaolin; Qu, Yaohui; Lai, Yanqing; Li, Jie

    2015-01-01

    Highlights: • A hybrid nanostructure that incorporate the merits of conductive polymer nanorods and graphite oxide sheets. • A novel approach based on interface polymerization for synthesizing CP/GO@S ternary composite. • CP/GO@S ternary composite cathode shows enhanced electrochemical properties compared with CP@S binary composite cathode. • PEDOT/GO@S composite is the material system that have best electrochemical performance in all CP/GO@S ternary composites. - Abstract: The novel ternary composites, conductive polymers (CPs)/graphene oxide (GO)@sulfur composites were successfully synthesized via a facile one-pot route and used as cathode materials for Li-S batteries The poly(3,4-ethylenedioxythiophene) (PEDOT)/GO and polyaniline (PANI)/GO composites were prepared by interface polymerization of monomers on the surface of GO sheets. Then sulfur was in-situ deposited on the CPs/GO composites in same solution. The component and structure of the composites were characterized by XPS, TGA, FTIR, SEM, TEM and electrochemical measurements. In this structure, the CPs nanostructures are believed to serve as a conductive matrix and an adsorbing agent, while the highly conductive GO will physically and chemically confine the sulfur and polysulfide within cathode. The PEDOT/GO@S composites with the sulfur content of 66.2 wt% exhibit a reversible discharge capacity of 800.2 mAh g −1 after 200 cycles at 0.5 C, which is much higher than that of PANI/GO@S composites (599.1 mAh g −1 ) and PANI@S (407.2 mAh g −1 ). Even at a high rate of 4 C, the PEDOT/GO@S composites still retain a high specific capacity of 632.4 mAh g −1

  11. Adsorption of sulfur compound utilizing rice husk ash modified with niobium

    International Nuclear Information System (INIS)

    Cavalcanti, Rodrigo M.; Pessoa Júnior, Wanison A.G.; Braga, Valdeilson S.; Barros, Ivoneide de C.L.

    2015-01-01

    Graphical abstract: - Highlights: • Adsorbents based in RHA modified with niobium were prepared by impregnation. • The impregnation modified the particle size and topology of RHA particles. • The adsorbents were applied in sulfur removal in model liquid fuels. • The larger sulfur removal (>50%) was achieved using RHA with 5 wt.% niobium oxide. • The adsorbent show great selectivity in adsorption experiments. - Abstract: Adsorbents based in rice husk ash (RHA) modified with niobium pentoxide were prepared for impregnation methods and applied in sulfur removal in liquid fuels. The solids were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption and thermal analysis; they show that there was no qualitative change in the amorphous structure of the RHA; however, the method of impregnation could modify the particle size and topology of RHA particles. The larger sulfur removal (>50%) was achieved using RHA with 5 wt.% Nb 2 O 5 at a dosage of 10 g L −1 , after 4 h of contact with the model fuel. The kinetic study of adsorption of thiophene showed that the models of pseudo-second order and intra-particle diffusion best fit the experimental data. The adsorption experiments with the thiophenic derivatives compounds show a large selectivity of the adsorbent.

  12. Adsorption of sulfur compound utilizing rice husk ash modified with niobium

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcanti, Rodrigo M.; Pessoa Júnior, Wanison A.G. [Laboratório de Catálise Química e Materiais (CATAMA), Instituto de Ciências Exatas, Universidade Federal do Amazonas (UFAM), Av. Gen. Rodrigo Otávio Jordão Ramos, 6200, 69077-000 Manaus, AM (Brazil); Braga, Valdeilson S. [Laboratório de Catálise, Centro das Ciências Exatas e das Tecnologias, Universidade Federal do Oeste da Bahia, Rua Professor José Seabra de Lemos, 316, Recanto dos Pássaros, 47808-021 Barreira, BA (Brazil); Barros, Ivoneide de C.L., E-mail: iclbarros@gmail.com [Laboratório de Catálise Química e Materiais (CATAMA), Instituto de Ciências Exatas, Universidade Federal do Amazonas (UFAM), Av. Gen. Rodrigo Otávio Jordão Ramos, 6200, 69077-000 Manaus, AM (Brazil)

    2015-11-15

    Graphical abstract: - Highlights: • Adsorbents based in RHA modified with niobium were prepared by impregnation. • The impregnation modified the particle size and topology of RHA particles. • The adsorbents were applied in sulfur removal in model liquid fuels. • The larger sulfur removal (>50%) was achieved using RHA with 5 wt.% niobium oxide. • The adsorbent show great selectivity in adsorption experiments. - Abstract: Adsorbents based in rice husk ash (RHA) modified with niobium pentoxide were prepared for impregnation methods and applied in sulfur removal in liquid fuels. The solids were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption and thermal analysis; they show that there was no qualitative change in the amorphous structure of the RHA; however, the method of impregnation could modify the particle size and topology of RHA particles. The larger sulfur removal (>50%) was achieved using RHA with 5 wt.% Nb{sub 2}O{sub 5} at a dosage of 10 g L{sup −1}, after 4 h of contact with the model fuel. The kinetic study of adsorption of thiophene showed that the models of pseudo-second order and intra-particle diffusion best fit the experimental data. The adsorption experiments with the thiophenic derivatives compounds show a large selectivity of the adsorbent.

  13. Acquisition of a Novel Sulfur-Oxidizing Symbiont in the Gutless Marine Worm Inanidrilus exumae

    Science.gov (United States)

    2018-01-01

    ABSTRACT Gutless phallodrilines are marine annelid worms without a mouth or gut, which live in an obligate association with multiple bacterial endosymbionts that supply them with nutrition. In this study, we discovered an unusual symbiont community in the gutless phallodriline Inanidrilus exumae that differs markedly from the microbiomes of all 22 of the other host species examined. Comparative 16S rRNA gene sequence analysis and fluorescence in situ hybridization revealed that I. exumae harbors cooccurring gamma-, alpha-, and deltaproteobacterial symbionts, while all other known host species harbor gamma- and either alpha- or deltaproteobacterial symbionts. Surprisingly, the primary chemoautotrophic sulfur oxidizer “Candidatus Thiosymbion” that occurs in all other gutless phallodriline hosts does not appear to be present in I. exumae. Instead, I. exumae harbors a bacterial endosymbiont that resembles “Ca. Thiosymbion” morphologically and metabolically but originates from a novel lineage within the class Gammaproteobacteria. This endosymbiont, named Gamma 4 symbiont here, had a 16S rRNA gene sequence that differed by at least 7% from those of other free-living and symbiotic bacteria and by 10% from that of “Ca. Thiosymbion.” Sulfur globules in the Gamma 4 symbiont cells, as well as the presence of genes characteristic for autotrophy (cbbL) and sulfur oxidation (aprA), indicate that this symbiont is a chemoautotrophic sulfur oxidizer. Our results suggest that a novel lineage of free-living bacteria was able to establish a stable and specific association with I. exumae and appears to have displaced the “Ca. Thiosymbion” symbionts originally associated with these hosts. IMPORTANCE All 22 gutless marine phallodriline species examined to date live in a highly specific association with endosymbiotic, chemoautotrophic sulfur oxidizers called “Ca. Thiosymbion.” These symbionts evolved from a single common ancestor and represent the ancestral trait for

  14. Specific ability of sulfur-ligands on removal of 203Hg-labeled organomercury from hemoglobin in comparison with nitrogen-ligands

    International Nuclear Information System (INIS)

    Hojo, Yasuji; Sugiura, Yukio; Tanaka, Hisashi

    1975-01-01

    Removal of 203 Hg-labeled organomercurials, bound to sulfhydryl groups of hemoglobin, by various chelating agents was investigated by the use of equilibrium dialysis. Organomercurials employed were chlormerodrin, methylmercury, ethylmercury and phenylmercury compounds. Higher and more specific effects of the sulfur-ligands, such as penicillamine and glutathione, on removal of organomercurial were found as compared with those of the nitrogen-ligands such as EDTA, glycine and polymethylenediamines. Linear correlation was observed between the degree of organomercury elimination from hemoglobin and the stability constant (log K 1 ) of 1:1 organomercury complex in both the sulfur- and nitrogen-ligand systems and at the same value of log K 1 , the elimination-effect of sulfur-ligands was extremely greater than that of the nitrogen-ligands. The relationship between the average percentage of removal and the Taft's polar substituent constant of organic moiety of the metal was also linear among the organomercury compounds other than chlormerodrin. The average removal percentage by sulfur-ligands increased in the order, ethylmercury>methylmercury>phenylmercury, while that of the nitrogen-ligands was not different among the organomercurials investigated. In addition, direct ligand-exchange reaction between hemoglobin-SH and the ligand coordinating-atom (S or N) against organomercurials rather than Ssub(N2) reaction via the ternary complex, hemoglobin-S-RHg-ligand, is postulated. (auth.)

  15. 40 CFR 52.125 - Control strategy and regulations: Sulfur oxides.

    Science.gov (United States)

    2010-07-01

    ... to existing fuel burning equipment producing electrical energy will provide for the attainment and...: Sulfur oxides. 52.125 Section 52.125 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... since the control strategy does not analyze the impact of smelter fugitive emissions on ambient air...

  16. Thermal stress analysis of sulfur deactivated solid oxide fuel cells

    Science.gov (United States)

    Zeng, Shumao; Parbey, Joseph; Yu, Guangsen; Xu, Min; Li, Tingshuai; Andersson, Martin

    2018-03-01

    Hydrogen sulfide in fuels can deactivate catalyst for solid oxide fuel cells, which has become one of the most critical challenges to stability. The reactions between sulfur and catalyst will cause phase changes, leading to increase in cell polarization and mechanical mismatch. A three-dimensional computational fluid dynamics (CFD) approach based on the finite element method (FEM) is thus used to investigate the polarization, temperature and thermal stress in a sulfur deactivated SOFC by coupling equations for gas-phase species, heat, momentum, ion and electron transport. The results indicate that sulfur in fuels can strongly affect the cell polarization and thermal stresses, which shows a sharp decrease in the vicinity of electrolyte when 10% nickel in the functional layer is poisoned, but they remain almost unchanged even when the poisoned Ni content was increased to 90%. This investigation is helpful to deeply understand the sulfur poisoning effects and also benefit the material design and optimization of electrode structure to enhance cell performance and lifetimes in various hydrocarbon fuels containing impurities.

  17. Molecular characterization of anaerobic sulfur-oxidizing microbial communities in up-flow anaerobic sludge blanket reactor treating municipal sewage.

    Science.gov (United States)

    Aida, Azrina A; Hatamoto, Masashi; Yamamoto, Masamitsu; Ono, Shinya; Nakamura, Akinobu; Takahashi, Masanobu; Yamaguchi, Takashi

    2014-11-01

    A novel wastewater treatment system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with sulfur-redox reaction was developed for treatment of municipal sewage under low-temperature conditions. In the UASB reactor, a novel phenomenon of anaerobic sulfur oxidation occurred in the absence of oxygen, nitrite and nitrate as electron acceptors. The microorganisms involved in anaerobic sulfur oxidation have not been elucidated. Therefore, in this study, we studied the microbial communities existing in the UASB reactor that probably enhanced anaerobic sulfur oxidation. Sludge samples collected from the UASB reactor before and after sulfur oxidation were used for cloning and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes of the bacterial and archaeal domains. The microbial community structures of bacteria and archaea indicated that the genus Smithella and uncultured bacteria within the phylum Caldiserica were the dominant bacteria groups. Methanosaeta spp. was the dominant group of the domain archaea. The T-RFLP analysis, which was consistent with the cloning results, also yielded characteristic fingerprints for bacterial communities, whereas the archaeal community structure yielded stable microbial community. From these results, it can be presumed that these major bacteria groups, genus Smithella and uncultured bacteria within the phylum Caldiserica, probably play an important role in sulfur oxidation in UASB reactors. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  18. Sulfur-doped graphene via thermal exfoliation of graphite oxide in H2S, SO2, or CS2 gas.

    Science.gov (United States)

    Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

    2013-06-25

    Doping of graphene with heteroatoms is an effective way to tailor its properties. Here we describe a simple and scalable method of doping graphene lattice with sulfur atoms during the thermal exfoliation process of graphite oxides. The graphite oxides were first prepared by Staudenmaier, Hofmann, and Hummers methods followed by treatments in hydrogen sulfide, sulfur dioxide, or carbon disulfide. The doped materials were characterized by scanning electron microscopy, high-resolution X-ray photoelectron spectroscopy, combustible elemental analysis, and Raman spectroscopy. The ζ-potential and conductivity of sulfur-doped graphenes were also investigated in this paper. It was found that the level of doping is more dramatically influenced by the type of graphite oxide used rather than the type of sulfur-containing gas used during exfoliation. Resulting sulfur-doped graphenes act as metal-free electrocatalysts for an oxygen reduction reaction.

  19. Selective oxidation of refractory sulfur compounds for the production of low sulfur transportation fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Kwang-Eun; Kim, Tae-Wan; Kim, Joo-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Jeong, Soon-Yong [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Park, Young-Kwon [University of Seoul, Seoul (Korea, Republic of)

    2013-03-15

    The current technologies for achieving low sulfur in diesel fuel are based on hydrotreating, which requires high temperature, high pressure and excessive supply of hydrogen. Oxidative desulfurization (ODS) is considered one of the promising new methods for super deep desulfurization, which could be carried out under very mild conditions (atmospheric pressure, <100 .deg.. C) without consumption of hydrogen. In this paper, development status of ODS process by major licensors are described as well as general concepts of ODS reaction. In addition, the ODS process has been categorized into single phasic and biphasic system according to the oxidants involved. Recent trends in both systems are reviewed in detail and future work is also proposed.

  20. Selective oxidation of refractory sulfur compounds for the production of low sulfur transportation fuel

    International Nuclear Information System (INIS)

    Jeong, Kwang-Eun; Kim, Tae-Wan; Kim, Joo-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Jeong, Soon-Yong; Park, Young-Kwon

    2013-01-01

    The current technologies for achieving low sulfur in diesel fuel are based on hydrotreating, which requires high temperature, high pressure and excessive supply of hydrogen. Oxidative desulfurization (ODS) is considered one of the promising new methods for super deep desulfurization, which could be carried out under very mild conditions (atmospheric pressure, <100 .deg.. C) without consumption of hydrogen. In this paper, development status of ODS process by major licensors are described as well as general concepts of ODS reaction. In addition, the ODS process has been categorized into single phasic and biphasic system according to the oxidants involved. Recent trends in both systems are reviewed in detail and future work is also proposed

  1. Sulfur isotope fractionation during heterogeneous oxidation of SO2 on mineral dust

    Directory of Open Access Journals (Sweden)

    P. Hoppe

    2012-06-01

    Full Text Available Mineral dust is a major fraction of global atmospheric aerosol, and the oxidation of SO2 on mineral dust has implications for cloud formation, climate and the sulfur cycle. Stable sulfur isotopes can be used to understand the different oxidation processes occurring on mineral dust. This study presents measurements of the 34S/32S fractionation factor α34 for oxidation of SO2 on mineral dust surfaces and in the aqueous phase in mineral dust leachate. Sahara dust, which accounts for ~60% of global dust emissions and loading, was used for the experiments. The fractionation factor for aqueous oxidation in dust leachate is αleachate = 0.9917±0.0046, which is in agreement with previous measurements of aqueous SO2 oxidation by iron solutions. This fractionation factor is representative of a radical chain reaction oxidation pathway initiated by transition metal ions. Oxidation on the dust surface at subsaturated relative humidity (RH had an overall fractionation factor of αhet = 1.0096±0.0036 and was found to be almost an order of magnitude faster when the dust was simultaneously exposed to ozone, light and RH of ~40%. However, the presence of ozone, light and humidity did not influence isotope fractionation during oxidation on dust surfaces at subsaturated relative humidity. All the investigated reactions showed mass-dependent fractionation of 33S relative to 34S. A positive matrix factorization model was used to investigate surface oxidation on the different components of dust. Ilmenite, rutile and iron oxide were found to be the most reactive components, accounting for 85% of sulfate production with a fractionation factor of α34 = 1.012±0.010. This overlaps within the analytical uncertainty with the fractionation of other major atmospheric oxidation pathways such as the oxidation of SO2 by H2O2 and O3 in the aqueous phase and OH in the gas phase. Clay minerals accounted for roughly 12% of the sulfate production, and oxidation on clay minerals

  2. Oxidation-sulfidation behavior of Ni aluminide in oxygen-sulfur mixed-gas atmospheres

    International Nuclear Information System (INIS)

    Natesan, K.

    1988-01-01

    Oxidation-sulfidation studies were conducted with sheet samples of nickel aluminide, containing 23.5 at. % Al, 0.5 at. % Hf, and 0.2 at. % B, in an annealed condition and after preoxidation treatments. Continuous weight-change measurements were made by a thermogravimetric technique in exposure atmospheres of air, a low-pO/sub 2/ gas mixture, and low-pO/sub 2/ gas mixtures with several levels of sulfur. The air-exposed specimens developed predominantly nickel oxide; the specimen exposed to a low-pO/sub 2/ environment developed an aluminum oxide scale. As the sulfur content of the gas mixture increased, the alumina scale exhibited spallation and the alloy tended to form nickel sulfide as the reaction phase. The results indicated that the sulfidation reaction of nickel aluminide specimens (both bare and preoxidized) was determined by the rate of transport of nickel from the substrate through the scale to the gas/alumina scale interface, the mechanical integrity of the oxide scale, and the H/sub 2/S concentration in the exposure environment

  3. Multi-component removal in flue gas by aqua ammonia

    Science.gov (United States)

    Yeh, James T [Bethel Park, PA; Pennline, Henry W [Bethel Park, PA

    2007-08-14

    A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO.sub.2) and nitric oxide (NO) and nitrous oxide (N.sub.2O) to sulfur trioxide (SO.sub.3) and nitrogen dioxide (NO.sub.2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.

  4. Removal of H2S and volatile organic sulfur compounds by silicone membrane extraction

    NARCIS (Netherlands)

    Manconi, I.; Lens, P.N.L.

    2009-01-01

    BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the

  5. Functional bacteria and process metabolism of the Denitrifying Sulfur conversion-associated Enhanced Biological Phosphorus Removal (DS-EBPR) system: An investigation by operating the system from deterioration to restoration.

    Science.gov (United States)

    Guo, Gang; Wu, Di; Hao, Tianwei; Mackey, Hamish Robert; Wei, Li; Wang, Haiguang; Chen, Guanghao

    2016-05-15

    A sulfur conversion-associated Enhanced Biological Phosphorus (P) Removal (EBPR) system is being developed to cater for the increasing needs to treat saline/brackish wastewater resulting from seawater intrusion into groundwater and sewers and frequent use of sulfate coagulants during drinking water treatment, as well as to meet the demand for eutrophication control in warm climate regions. However, the major functional bacteria and metabolism in this emerging biological nutrient removal system are still poorly understood. This study was thus designed to explore the functional microbes and metabolism in this new EBPR system by manipulating the deterioration, failure and restoration of a lab-scale system. This was achieved by changing the mixed liquor suspended solids (MLSS) concentration to monitor and evaluate the relationships among sulfur conversion (including sulfate reduction and sulfate production), P removal, variation in microbial community structures, and stoichiometric parameters. The results show that the stable Denitrifying Sulfur conversion-associated EBPR (DS-EBPR) system was enriched by sulfate-reducing bacteria (SRB) and sulfide-oxidizing bacteria (SOB). These bacteria synergistically participated in this new EBPR process, thereby inducing an appropriate level of sulfur conversion crucial for achieving a stable DS-EBPR performance, i.e. maintaining sulfur conversion intensity at 15-40 mg S/L, corresponding to an optimal sludge concentration of 6.5 g/L. This range of sulfur conversion favors microbial community competition and various energy flows from internal polymers (i.e. polysulfide or elemental sulfur (poly-S(2-)/S(0)) and poly-β-hydroxyalkanoates (PHA)) for P removal. If this range was exceeded, the system might deteriorate or even fail due to enrichment of glycogen-accumulating organisms (GAOs). Four methods of restoring the failed system were investigated: increasing the sludge concentration, lowering the salinity or doubling the COD

  6. Durability of solid oxide fuel cells using sulfur containing fuels

    DEFF Research Database (Denmark)

    Hagen, Anke; Rasmussen, Jens Foldager Bregnballe; Thydén, Karl Tor Sune

    2011-01-01

    The usability of hydrogen and also carbon containing fuels is one of the important advantages of solid oxide fuel cells (SOFCs), which opens the possibility to use fuels derived from conventional sources such as natural gas and from renewable sources such as biogas. Impurities like sulfur compounds...... are critical in this respect. State-of-the-art Ni/YSZ SOFC anodes suffer from being rather sensitive towards sulfur impurities. In the current study, anode supported SOFCs with Ni/YSZ or Ni/ScYSZ anodes were exposed to H2S in the ppm range both for short periods of 24h and for a few hundred hours. In a fuel...

  7. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules

    CERN Document Server

    Schobesberger, Siegfried; Bianchi, Federico; Lönn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-01-01

    Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molec...

  8. [Oxidation of sulfur-containing substrates by aboriginal and experimentally designed microbial communities].

    Science.gov (United States)

    Pivovarova, T A; Bulaev, A G; Roshchupko, P V; Belyĭ, A V; Kondrat'eva, T F

    2012-01-01

    Aboriginal and experimental (constructed of pure microbial cultures) communities of acidophilic chemolithotrophs have been studied. The oxidation of elemental sulfur, sodium thiosulfate, and potassium tetrathionate as sole sources of energy has been monitored. The oxidation rate of the experimental community is higher as compared to the aboriginal community isolated from a flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore. The degree of oxidation of the mentioned S substrates amounts to 17.91, 68.30, and 93.94% for the experimental microbial community and to 10.71, 56.03, and 79.50% for the aboriginal community, respectively. The degree of oxidation of sulfur sulfide forms in the ore flotation concentrate is 59.15% by the aboriginal microbial community and 49.40% by the experimental microbial community. Despite a higher rate of oxidation of S substrates as a sole source of energy by the experimental microbial community, the aboriginal community oxidizes S substrates at a higher rate in the flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore, from which it was isolated. Bacterial-chemical oxidation of the flotation concentrate by the aboriginal microbial community allows for the extraction of an additional 32.3% of gold from sulfide minerals, which is by 5.7% larger compared to the yield obtained by the experimental microbial community.

  9. Economic analysis of ultrasound-assisted oxidative desulfurization

    OpenAIRE

    Anderson, K.; Atkins, M.P.; Borges, P; Chan, Z.P.; Rafeen, M.S.; Sebran, N.H.; van der Pool, E; Vleeming, J.H.

    2017-01-01

    Oxidative desulfurization is a method of removing sulfur from diesel fuel that has the potential to compete with conventional hydrodesulfurization processes in refineries. Ultrasound has been shown to greatly increase peroxide oxidation rates of sulfur compounds and can thereby enhance the technology. Through the use of conceptual design modeling, this article critically assesses a range of novel process options. Calculations show that the rate enhancement achieved by ultrasound can translate...

  10. Retention of sulfur and nitrogen oxides from the exhaust gases by radiolysis, a modern method of environmental protection

    International Nuclear Information System (INIS)

    Macarie, Rodica; Zissulescu, Ecaterina; Martin, Diana; Radoiu, Marilena

    2000-01-01

    Industry, especially the power industry, is a great generator of gaseous pollutants (SO x , NO x , CO 2 , CO). The oxides are responsible for the 'acid rains' which have a great negative impact on the environment, human beings and animals, while CO 2 emissions contribute to the increase of the greenhouse effect. Retention of the sulfur and nitrogen oxides from the exhaust gases can be carried out either by conventional methods (using chemical adsorbents) or by non-conventional ones (radiolysis). Recently, non-conventional methods have bee given priority, including exhaust gas irradiation with an accelerated electron beam as a more efficient alternative to the gas desulfurization. In order to increase the efficiency of the accelerated electron beam injected into the exhaust gas, the effect of microwave utilization has been investigated. The company S.C. ICPET S.A.-Bucuresti, in cooperation with INFLPR-Bucuresti, investigated the retention by radiolysis of the sulfur and nitrogen oxides from a synthetic mixture of exhaust gases in an installation developed in the laboratory by means of accelerated electron beams, microwaves and by the accelerated electron beams and microwave combined. The paper presents the results obtained in the laboratory experiments and the advantages of radiolysis in comparison with the chemical conventional methods, namely: simultaneous removal of SO 2 and NO x , solid by-products that can be used as fertilizers in agriculture, simple technologies that do not imply catalysts or adsorbents, no waste waters. (authors)

  11. Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

    Directory of Open Access Journals (Sweden)

    Jafari Mohammad Javad

    2012-12-01

    Full Text Available Abstract The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p 3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream.

  12. Dynamic transition of chemolithotrophic sulfur-oxidizing bacteria in response to amendment with nitrate in deposited marine sediments

    Directory of Open Access Journals (Sweden)

    Tomo eAoyagi

    2015-05-01

    Full Text Available Although environmental stimuli are known to affect the structure and function of microbial communities, their impact on the metabolic network of microorganisms has not been well investigated. Here, geochemical analyses, high-throughput sequencing of 16S rRNA genes and transcripts, and isolation of potentially relevant bacteria were carried out to elucidate the anaerobic respiration processes stimulated by nitrate (20 mM amendment of marine sediments. Marine sediments deposited by the Great East Japan Earthquake in 2011 were incubated anaerobically in the dark at 25°C for 5 days. Nitrate in slurry water decreased gradually for 2 days, then more rapidly until its complete depletion at day 5; production of N2O followed the same pattern. From day 2 to 5, the sulfate concentration increased and the sulfur content in solid-phase sediments significantly decreased. These results indicated that denitrification and sulfur oxidation occurred simultaneously. Illumina sequencing revealed the proliferation of known sulfur oxidizers, i.e., Sulfurimonas spp. and Chromatiales bacteria, which accounted for approximately 43.5% and 14.8% of the total population at day 5, respectively. They also expressed 16S rRNA to a considerable extent, whereas the other microorganisms, e.g., iron(III reducers and methanogens, became metabolically active at the end of the incubation. Extinction dilution culture in a basal-salts medium supplemented with sulfur compounds and nitrate successfully isolated the predominant sulfur oxidizers: Sulfurimonas sp. strain HDS01 and Thioalkalispira sp. strain HDS22. Their 16S rRNA genes showed 95.2−96.7% sequence similarity to the closest cultured relatives and they grew chemolithotrophically on nitrate and sulfur. Novel sulfur-oxidizing bacteria were thus directly involved in carbon fixation under nitrate-reducing conditions, activating anaerobic respiration processes and the reorganization of microbial communities in the deposited marine

  13. Isolation and characterization of ferrous- and sulfur-oxidizing bacteria from Tengchong solfataric region, China.

    Science.gov (United States)

    Jiang, Chengying; Liu, Ying; Liu, Yanyang; Guo, Xu; Liu, Shuang-Jiang

    2009-01-01

    Microbial oxidation and reduction of iron and sulfur are important parts of biogeochemical cycles in acidic environments such as geothermal solfataric regions. Species of Acidithiobacillus and Leptospirillum are the common ferrous-iron and sulfur oxidizers from such environments. This study focused on the Tengchong sofataric region, located in Yunnan Province, Southwest China. Based on cultivation, 9 strains that grow on ferrous-iron and sulfuric compounds were obtained. Analysis of 16S rRNA genes of the 9 strains indicated that they were affiliated to Acidithiobacillus, Alicyclobacillus, Sulfobacillus, Leptospirillum and Acidiphilium. Physiological and phylogenetic studies indicated that two strains (TC-34 and TC-71) might represent two novel members of Alicyclobacillus. Strain TC-34 and TC-71 showed 94.8%-97.1% 16S rRNA gene identities to other species of Alicyclobacillus. Different from the previously described Alicyclobacillus species, strains TC-34 and TC-71 were mesophilic and their cellular fatty acids do not contain omega-cyclic fatty acids. Strain TC-71 was obligately dependent on ferrous-iron for growth. It was concluded that the ferrous-iron oxidizers were diversified and Alicyclobacillus species were proposed to take part in biochemical geocycling of iron in the Tengchong solfataric region.

  14. Oxidation of phosphine by sulfur or selenium involving a catalytic ...

    Indian Academy of Sciences (India)

    Administrator

    P NMR spec- troscopy. Such interconversion with the participation of breaking of bridging copper-µ3-sulfur bond with the formation of new copper–phosphorous bond led to the development of a catalytic cycle using excess. PPh3 and S or Se as the reacting substrates. The turnover number for the oxidation of PPh3 by S ...

  15. Balancing surface adsorption and diffusion of lithium-polysulfides on nonconductive oxides for lithium?sulfur battery design

    OpenAIRE

    Tao, Xinyong; Wang, Jianguo; Liu, Chong; Wang, Haotian; Yao, Hongbin; Zheng, Guangyuan; Seh, Zhi Wei; Cai, Qiuxia; Li, Weiyang; Zhou, Guangmin; Zu, Chenxi; Cui, Yi

    2016-01-01

    Lithium?sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understandin...

  16. The significance of elemental sulfur dissolution in liquid electrolyte lithium sulfur batteries

    NARCIS (Netherlands)

    Harks, Peter Paul R.M.L.; Robledo, Carla B.; Verhallen, Tomas W.; Notten, Peter H.L.; Mulder, Fokko M.

    2017-01-01

    It is shown that the dissolution of elemental sulfur into, and its diffusion through, the electrolyte allows cycling of lithium–sulfur batteries in which the sulfur is initially far removed and electrically insulated from the current collector. These findings help to understand why liquid

  17. Molecular analysis of the diversity of sulfate-reducing and sulfur-oxidizing prokaryotes in the environment, using aprA as functional marker gene.

    Science.gov (United States)

    Meyer, Birte; Kuever, Jan

    2007-12-01

    The dissimilatory adenosine-5'-phosphosulfate reductase is a key enzyme of the microbial sulfate reduction and sulfur oxidation processes. Because the alpha- and beta-subunit-encoding genes, aprBA, are highly conserved among sulfate-reducing and sulfur-oxidizing prokaryotes, they are most suitable for molecular profiling of the microbial community structure of the sulfur cycle in environment. In this study, a new aprA gene-targeting assay using a combination of PCR and denaturing gradient gel electrophoresis is presented. The screening of sulfate-reducing and sulfur-oxidizing reference strains as well as the analyses of environmental DNA from diverse habitats (e.g., microbial mats, invertebrate tissue, marine and estuarine sediments, and filtered hydrothermal water) by the new primer pair revealed an improved microbial diversity coverage and less-pronounced template-to-PCR product bias in direct comparison to those of the previously published primer set (B. Deplancke, K. R. Hristova, H. A. Oakley, V. J. McCracken, R. Aminov, R. I. Mackie, and H. R. Gaskins, Appl. Environ. Microbiol. 66:2166-2174, 2000). The concomitant molecular detection of sulfate-reducing and sulfur-oxidizing prokaryotes was confirmed. The new assay was applied in comparison with the 16S rRNA gene-based analysis to investigate the microbial diversity of the sulfur cycle in sediment, seawater, and manganese crust samples from four study sites in the area of the Lesser Antilles volcanic arc, Caribbean Sea (Caribflux project). The aprA gene-based approach revealed putative sulfur-oxidizing Alphaproteobacteria of chemolithoheterotrophic lifestyle to have been abundant in the nonhydrothermal sediment and water column. In contrast, the sulfur-based microbial community that inhabited the surface of the volcanic manganese crust was more complex, consisting predominantly of putative chemolithoautotrophic sulfur oxidizers of the Betaproteobacteria and Gammaproteobacteria.

  18. Growth kinetics of hydrogen sulfide oxidizing bacteria in corroded concrete from sewers

    International Nuclear Information System (INIS)

    Jensen, Henriette Stokbro; Lens, Piet N.L.; Nielsen, Jeppe L.; Bester, Kai; Nielsen, Asbjorn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2011-01-01

    Hydrogen sulfide oxidation by microbes present on concrete surfaces of sewer pipes is a key process in sewer corrosion. The growth of aerobic sulfur oxidizing bacteria from corroded concrete surfaces was studied in a batch reactor. Samples of corrosion products, containing sulfur oxidizing bacteria, were suspended in aqueous solution at pH similar to that of corroded concrete. Hydrogen sulfide was supplied to the reactor to provide the source of reduced sulfur. The removal of hydrogen sulfide and oxygen was monitored. The utilization rates of both hydrogen sulfide and oxygen suggested exponential bacterial growth with median growth rates of 1.25 d -1 and 1.33 d -1 as determined from the utilization rates of hydrogen sulfide and oxygen, respectively. Elemental sulfur was found to be the immediate product of the hydrogen sulfide oxidation. When exponential growth had been achieved, the addition of hydrogen sulfide was terminated leading to elemental sulfur oxidation. The ratio of consumed sulfur to consumed oxygen suggested that sulfuric acid was the ultimate oxidation product. To the knowledge of the authors, this is the first study to determine the growth rate of bacteria involved in concrete corrosion with hydrogen sulfide as source of reduced sulfur.

  19. Genomic analysis reveals versatile heterotrophic capacity of a potentially symbiotic sulfur-oxidizing bacterium in sponge

    KAUST Repository

    Tian, Renmao

    2014-08-29

    Sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play essential roles in marine sponges. However, the detailed characteristics and physiology of the bacteria are largely unknown. Here, we present and analyse the first genome of sponge-associated SOB using a recently developed metagenomic binning strategy. The loss of transposase and virulence-associated genes and the maintenance of the ancient polyphosphate glucokinase gene suggested a stabilized SOB genome that might have coevolved with the ancient host during establishment of their association. Exclusive distribution in sponge, bacterial detoxification for the host (sulfide oxidation) and the enrichment for symbiotic characteristics (genes-encoding ankyrin) in the SOB genome supported the bacterial role as an intercellular symbiont. Despite possessing complete autotrophic sulfur oxidation pathways, the bacterium developed a much more versatile capacity for carbohydrate uptake and metabolism, in comparison with its closest relatives (Thioalkalivibrio) and to other representative autotrophs from the same order (Chromatiales). The ability to perform both autotrophic and heterotrophic metabolism likely results from the unstable supply of reduced sulfur in the sponge and is considered critical for the sponge-SOB consortium. Our study provides insights into SOB of sponge-specific clade with thioautotrophic and versatile heterotrophic metabolism relevant to its roles in the micro-environment of the sponge body. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. Fuel processor integrated H{sub 2}S catalytic partial oxidation technology for sulfur removal in fuel cell power plants

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, T.H.; Berry, D.A.; Lyons, K.D.; Beer, S.K.; Freed, A.D. [U.S. Department of Energy, Morgantown, WV (USA). National Energy Technology Laboratory

    2002-12-01

    H{sub 2}S catalytic partial oxidation technology with an activated carbon catalyst was found to be a promising method for the removal of hydrogen sulfide from fuel cell hydrocarbon feedstocks. Three different fuel cell feedstocks were considered for analysis: sour natural gas, sour effluent from a liquid middle distillate fuel processor and a Texaco O{sub 2}-blown coal-derived synthesis gas. The H{sub 2}S catalytic partial oxidation reaction, its integratability into fuel cell power plants with different hydrocarbon feedstocks and its salient features are discussed. Experimental results indicate that H{sub 2}S concentration can be removed down to the part-per-million level in these plants. Additionally, a power law rate expression was developed and reaction kinetics compared to prior literature. The activation energy for this reaction was determined to be 34.4 kJ/g mol with the reaction being first order in H{sub 2}S and 0.3 order in O{sub 2}. 18 refs., 14 figs., 3 tabs.

  1. Genomic Insights into the Sulfur Metabolism of Phototrophic Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Bryant, Donald A.

    2008-01-01

    Green sulfur bacteria (GSB) utilize various combinations of sulfide, elemental sulfur, thiosulfate, ferrous iron, and hydrogen for anaerobic photoautotrophic growth. Genome sequence data is currently available for 12 strains of GSB. We present here a genome-based survey of the distribution...... and phylogenies of genes involved in oxidation of sulfur compounds in these strains. Sulfide:quinone reductase, encoded by sqr, is the only known sulfur-oxidizing enzyme found in all strains. All sulfide-utilizing strains contain the dissimilatory sulfite reductase dsrABCEFHLNMKJOPT genes, which appear...... to be involved in elemental sulfur utilization. All thiosulfate-utilizing strains have an identical sox gene cluster (soxJXYZAKBW). The soxCD genes found in certain other thiosulfate-utilizing organisms like Paracoccus pantotrophus are absent from GSB. Genes encoding flavocytochrome c (fccAB), adenosine-5...

  2. Simultaneous removal of sulfur dioxide and polycyclic aromatic hydrocarbons from incineration flue gas using activated carbon fibers.

    Science.gov (United States)

    Liu, Zhen-Shu; Li, Wen-Kai; Hung, Ming-Jui

    2014-09-01

    Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO2). The effects of SO2 concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 degrees C), and the type of activated carbon fibers (ACFs) on the removal of SO2 and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO2 in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 degrees C on removal of PAHs was greater than that on SO2 removal at an SO2 concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO2 and PAHs when these gases coexisted in the incineration flue gas. Implications: Simultaneous adsorption of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO2 in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO2 removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO2 and PAHs.

  3. Effect of Iron Oxides (Ordinary and Nano and Municipal Solid Waste Compost (MSWC Coated Sulfur on Wheat (Triticum aestivum L. Plant Iron Concentration and Growth

    Directory of Open Access Journals (Sweden)

    S Mazaherinia

    2011-02-01

    Full Text Available Abstract A greenhouse study was conducted to compare the effects of ordinary iron oxide (0.02-0.06 mm and nano iron oxide (25-250 nm and five levels of both iron oxides (0, 0.05, 0.1, 0.5, and 1.0 %w/w and two levels of sulfurous granular compost (MSW (0 and 2% w/w on plant height, spike length, grain weight per spike, total plant dry matter weight and thousands grain weight of wheat. The experimental factors were combined in factorial arrangement in a completely randomized design with 3 replications. Results showed that nano iron oxide was superior over ordinary iron oxide in all parameters studied. Fe concentration, spike length, plant height, grain weight per spike, total plant dry weight and thousands grain weight showed increasing trend per increase in both of iron oxides levels. Also, all parameters studied in sulfurous granular compost (MSW treatment were superior over granular compost without sulfurous (MSW. This increase in all parameters were significantly higher when urban solid waste compost coated with sulfur coupled with nano iron oxide compared to urban sulfurous granular compost (MSW along with ordinary iron oxide. Keywords: Sulfurous granular compost (MSW, Nano and ordinary iron oxides, Wheat

  4. Sulfur-Modified Zero-Valent Iron for Remediation Applications at DOE Sites - 13600

    Energy Technology Data Exchange (ETDEWEB)

    Fogwell, Thomas W. [Fogwell Consulting, P.O. Box 20221, Piedmont, CA 94620 (United States); Santina, Pete [SMI-PS, Inc., 2073 Prado Vista, Lincoln, CA 95648 (United States)

    2013-07-01

    municipal water treatment applications. Sulfur-modified iron has been found to not only be an extremely economical treatment technology for municipal water supplies, where very large quantities of water must be treated economically, but it has also been demonstrated to immobilize technetium. It has the added benefit of eliminating several other harmful chemicals in water supplies. These include arsenic and selenium. In one large-scale evaluation study an integrated system implemented chemical reduction of nitrate with sulfur-modified iron followed by filtration for arsenic removal. The sulfur-modified iron that was used was an iron-based granular medium that has been commercially developed for the removal of nitrate, co-contaminants including uranium, vanadium and chromium, and other compounds from water. The independent study concluded that 'It is foreseen that the greatest benefit of this technology (sulfur-modified iron) is that it does not produce a costly brine stream as do the currently accepted nitrate removal technologies of ion exchange and reverse osmosis. This investigation confirmed that nitrate reduction via sulfur-modified iron is independent of the hydraulic loading rate. Future sulfur-modified iron treatment systems can be designed without restriction of the reactor vessel dimensions. Future vessels can be adapted to existing site constraints without being limited to height-to-width ratios that would exist if nitrate reduction were to depend on hydraulic loading rate'. Sulfur-modified iron was studied by the Pacific Northwest National Laboratory (PNNL) for its effectiveness in the reduction and permanent sequestration of technetium. The testing was done using Hanford Site groundwater together with sediment. The report stated, 'Under reducing conditions, TcO{sub 4} is readily reduced to TcIV, which forms highly insoluble oxides such at TcO{sub 2}.nH{sub 2}O. However, (re)oxidation of TcIV oxides can lead to remobilization. Under sulfidogenic

  5. The mechanism of the catalytic oxidation of hydrogen sulfide: II. Kinetics and mechanism of hydrogen sulfide oxidation catalyzed by sulfur

    NARCIS (Netherlands)

    Steijns, M.; Derks, F.; Verloop, A.; Mars, P.

    1976-01-01

    The kinetics of the catalytic oxidation of hydrogen sulfide by molecular oxygen have been studied in the temperature range 20–250 °C. The primary reaction product is sulfur which may undergo further oxidation to SO2 at temperatures above 200 °C. From the kinetics of this autocatalytic reaction we

  6. Genomic and Evolutionary Perspectives on Sulfur Metabolism in Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Bryant, Donald A.

    2008-01-01

    Green sulfur bacteria (GSB) are anaerobic photoautotrophs that oxidize sulfide, elemental sulfur, thiosulfate, ferrous iron, and hydrogen for growth. We present here an analysis of the distribution and evolution of enzymes involved in oxidation of sulfur compounds in GSB based on genome sequence......, in combination with phylogenetic analyses, suggests that the Dsr system in GSB could be a recent acquisition, which was obtained by lateral gene transfer in part from sulfideoxidizing bacteria and in part from sulfate-reducing bacteria. All thiosulfate-utilizing GSB strains have an identical sox gene cluster...

  7. Disproportionation of elemental sulfur by haloalkaliphilic bacteria from soda lakes.

    Science.gov (United States)

    Poser, Alexander; Lohmayer, Regina; Vogt, Carsten; Knoeller, Kay; Planer-Friedrich, Britta; Sorokin, Dimitry; Richnow, Hans-H; Finster, Kai

    2013-11-01

    Microbial disproportionation of elemental sulfur to sulfide and sulfate is a poorly characterized part of the anoxic sulfur cycle. So far, only a few bacterial strains have been described that can couple this reaction to cell growth. Continuous removal of the produced sulfide, for instance by oxidation and/or precipitation with metal ions such as iron, is essential to keep the reaction exergonic. Hitherto, the process has exclusively been reported for neutrophilic anaerobic bacteria. Here, we report for the first time disproportionation of elemental sulfur by three pure cultures of haloalkaliphilic bacteria isolated from soda lakes: the Deltaproteobacteria Desulfurivibrio alkaliphilus and Desulfurivibrio sp. AMeS2, and a member of the Clostridia, Dethiobacter alkaliphilus. All cultures grew in saline media at pH 10 by sulfur disproportionation in the absence of metals as sulfide scavengers. Our data indicate that polysulfides are the dominant sulfur species under highly alkaline conditions and that they might be disproportionated. Furthermore, we report the first organism (Dt. alkaliphilus) from the class Clostridia that is able to grow by sulfur disproportionation.

  8. Molecular Analysis of the Diversity of Sulfate-Reducing and Sulfur-Oxidizing Prokaryotes in the Environment, Using aprA as Functional Marker Gene▿ †

    Science.gov (United States)

    Meyer, Birte; Kuever, Jan

    2007-01-01

    The dissimilatory adenosine-5′-phosposulfate reductase is a key enzyme of the microbial sulfate reduction and sulfur oxidation processes. Because the alpha- and beta-subunit-encoding genes, aprBA, are highly conserved among sulfate-reducing and sulfur-oxidizing prokaryotes, they are most suitable for molecular profiling of the microbial community structure of the sulfur cycle in environment. In this study, a new aprA gene-targeting assay using a combination of PCR and denaturing gradient gel electrophoresis is presented. The screening of sulfate-reducing and sulfur-oxidizing reference strains as well as the analyses of environmental DNA from diverse habitats (e.g., microbial mats, invertebrate tissue, marine and estuarine sediments, and filtered hydrothermal water) by the new primer pair revealed an improved microbial diversity coverage and less-pronounced template-to-PCR product bias in direct comparison to those of the previously published primer set (B. Deplancke, K. R. Hristova, H. A. Oakley, V. J. McCracken, R. Aminov, R. I. Mackie, and H. R. Gaskins, Appl. Environ. Microbiol. 66:2166-2174, 2000). The concomitant molecular detection of sulfate-reducing and sulfur-oxidizing prokaryotes was confirmed. The new assay was applied in comparison with the 16S rRNA gene-based analysis to investigate the microbial diversity of the sulfur cycle in sediment, seawater, and manganese crust samples from four study sites in the area of the Lesser Antilles volcanic arc, Caribbean Sea (Caribflux project). The aprA gene-based approach revealed putative sulfur-oxidizing Alphaproteobacteria of chemolithoheterotrophic lifestyle to have been abundant in the nonhydrothermal sediment and water column. In contrast, the sulfur-based microbial community that inhabited the surface of the volcanic manganese crust was more complex, consisting predominantly of putative chemolithoautotrophic sulfur oxidizers of the Betaproteobacteria and Gammaproteobacteria. PMID:17921272

  9. Use of zeolites for the removal of volatile sulfur compounds from industrial waste gases and from natural gases

    Energy Technology Data Exchange (ETDEWEB)

    Dudzik,; Z,; Bilska, M

    1974-12-01

    The use of zeolites for the removal of sulfur dioxide from industrial waste gases and for the removal of hydrogen sulfide and volatile mercaptans from the natural gas or synthetic gas manufactured from coal is discussed. The effectiveness and cost of zeolite methods are superior to that of other methods. The best sorption properties with respect to sulfur dioxide are observed in faujasites and erionites. The molecular sieve 13X (a sodium form of low-silicon faujasite) is the most effective sorbent of hydrogen sulfide, produced commercially on a large scale. This zeolite is also a very effective catalyst for simultaneous oxygenation of hydrogen sulfide. The reaction with oxygen can begin at temperatures as low as -80/sup 0/C. The effectiveness of zeolite reactors is enhanced by the presence of oxygen in the gas being purified, and is hindered by the presence of water or water vapor. The extraordinary catalytic activity of sodium faujasites is due to free donors, and sulfur and oxygen ion donors at their surface. A zeolite reactor is also economical.

  10. Aircraft exhaust sulfur emissions

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R C; Anderson, M R; Miake-Lye, R C; Kolb, C E [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics; Sorokin, A A; Buriko, Y I [Scientific Research Center ` Ecolen` , Moscow (Russian Federation)

    1998-12-31

    The extent to which fuel sulfur is converted to SO{sub 3} during combustion and the subsequent turbine flow in supersonic and subsonic aircraft engines is estimated numerically. The analysis is based on: a flamelet model with non-equilibrium sulfur chemistry for the combustor, and a one-dimensional, two-stream model with finite rate chemical kinetics for the turbine. The results indicate that between 2% and 10% of the fuel sulfur is emitted as SO{sub 3}. It is also shown that, for a high fuel sulfur mass loading, conversion in the turbine is limited by the level of atomic oxygen at the combustor exit, leading to higher SO{sub 2} oxidation efficiency at lower fuel sulfur loadings. While SO{sub 2} and SO{sub 3} are the primary oxidation products, the model results further indicate H{sub 2}SO{sub 4} levels on the order of 0.1 ppm for supersonic expansions through a divergent nozzle. This source of fully oxidized S(6) (SO{sub 3} + H{sub 2}SO{sub 4}) exceeds previously calculated S(6) levels due to oxidation of SO{sub 2} by OH in the exhaust plume outside the engine nozzle. (author) 26 refs.

  11. Aircraft exhaust sulfur emissions

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.C.; Anderson, M.R.; Miake-Lye, R.C.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics; Sorokin, A.A.; Buriko, Y.I. [Scientific Research Center `Ecolen`, Moscow (Russian Federation)

    1997-12-31

    The extent to which fuel sulfur is converted to SO{sub 3} during combustion and the subsequent turbine flow in supersonic and subsonic aircraft engines is estimated numerically. The analysis is based on: a flamelet model with non-equilibrium sulfur chemistry for the combustor, and a one-dimensional, two-stream model with finite rate chemical kinetics for the turbine. The results indicate that between 2% and 10% of the fuel sulfur is emitted as SO{sub 3}. It is also shown that, for a high fuel sulfur mass loading, conversion in the turbine is limited by the level of atomic oxygen at the combustor exit, leading to higher SO{sub 2} oxidation efficiency at lower fuel sulfur loadings. While SO{sub 2} and SO{sub 3} are the primary oxidation products, the model results further indicate H{sub 2}SO{sub 4} levels on the order of 0.1 ppm for supersonic expansions through a divergent nozzle. This source of fully oxidized S(6) (SO{sub 3} + H{sub 2}SO{sub 4}) exceeds previously calculated S(6) levels due to oxidation of SO{sub 2} by OH in the exhaust plume outside the engine nozzle. (author) 26 refs.

  12. Results of Study of Sulfur Oxide Reduction During Combustion of Coal-Water Slurry Fuel Through use of Sulfur Capturing Agents

    Directory of Open Access Journals (Sweden)

    Murko Vasiliy I.

    2016-01-01

    Full Text Available It is shown that an effective way of burning high sulfur coal is to burn coal-water slurry fuel (CWF prepared on its basis containing a sulfur capture agent (SCA entered in the slurry at the stage of preparation. The technique of thermodynamic analysis of chemical reactions during CWF burning has been developed including burning in the presence of SCA. Using the developed calculation program, the optimal temperature conditions have been determined as required for the effective reduction of sulfur oxides in flue gases when using different types of SCA. According to the results of calculating the composition of CWF combustion products when entering various substances in the burner space as SCA it has been determined that magnesite, calcite, and dolomite are the most effective natural minerals. The analysis of calculated and experimental data proves the efficiency of SCA addition as well as validity of the obtained results.

  13. Tuning the oxidative power of free iron-sulfur clusters.

    Science.gov (United States)

    Lang, Sandra M; Zhou, Shaodong; Schwarz, Helmut

    2017-03-15

    The gas-phase reactions between a series of di-iron sulfur clusters Fe 2 S x + (x = 1-3) and the small alkenes C 2 H 4 , C 3 H 6 , and C 4 H 8 have been investigated by means of Fourier-transform ion-cyclotron resonance mass spectrometry. For all studied alkenes, the reaction efficiency is found to increase in the order Fe 2 S + desulfurization of the cluster and formation of H 2 S. This indicates an increased propensity to induce oxidation reactions, i.e. oxidative power, of Fe 2 S 3 + that is attributed to an increased formal oxidation state of the iron atoms. Furthermore, the ability of Fe 2 S 3 + to activate and dissociate the C-H bonds of the alkenes is observed to increase with increasing size of the alkene and thus correlates with the alkene ionization energy.

  14. Ultrasound-Assisted Oxidative Desulfurization of Diesel

    Directory of Open Access Journals (Sweden)

    Niran K. Ibrahim

    2016-11-01

    Full Text Available Due to the dramatic environmental impact of sulfur emissions associated with the exhaust of diesel engines, last environmental regulations for ultra-low-sulfur diesel require a very deep desulfurization (up to 15 ppm, which cannot be met by the conventional hydrodesulfurization units alone. The proposed method involves a batch ultrasound-assisted oxidative desulfurization (UAODS of a previously hydrotreated diesel (containing 480 ppm sulfur so as to convert the residual sulfur-bearing compounds into their corresponding highly polar oxides, which can be eliminated easily by extraction with a certain highly polar solvent. The oxidizing system utilized was H2O2 as an oxidant, CH3COOH as a promoter, with FeSO4 as a catalyst; whereas acetonitrile was used as extractant. The major influential parameters related to UAODS process have been investigated, namely: ratio of oxidant/fuel, ratio of the promoter/oxidant, dose of catalyst, reaction temperature, and intensity of ultrasonic waves. Kinetics of the reaction has been also studied; it was observed that the UAODS of diesel fuels fitted pseudo-first-order kinetics under the best experimental conditions, whereas values of the apparent rate constant and activation energy were 0.373 min-1 and 24 KJ/mol, respectively. The oxidation treatment, in combination with ultrasonic irradiation, revealed a synergistic effect for diesel desulfurization. The experimental results showed that sulfur removal efficiency could amount to 98% at mild operating conditions (70 ○C and 1 bar. This indicates that the process is efficient and promising for the production of ultra-low-sulfur diesel fuels.

  15. NO/sub x/ removal facility: MON process

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Y

    1974-05-01

    A newly developed process for nitrogen oxides removal is described. The MON process, named for Mitsubishi Kizoku, Okabe of Tohoku Univ., and Nippon Kagaku, uses potassium permanganate as an oxidizing agent. Potassium permanganate in alkaline solution converts nitric oxide into nitrate and nitrogen dioxide into nitric acid. The resulting MnO/sub 2/ is easily filtered and recovered as material for the manufacturing of KMnO/sub 4/. Contrary to the conventional methods, the NO/sub x/ conversion rate increases with increasing temperature. Test results at a pilot plant showed that NO/sub x/ was reduced from 570 ppM (nitric oxide 520 ppM) to 27 ppM (mostly NO) at 97 to 98 percent conversion. Another advantage of the process is that other acidic gases such as sulfur dioxide are also removed.

  16. Biogeochemistry of the sulfur oxidizer Thiomicrospira thermophila

    Science.gov (United States)

    Houghton, J.; Fike, D. A.; Wills, E.; Foustoukos, D.

    2013-12-01

    Near-seafloor hydrothermal environments such as diffuse flow venting or subsurface mixing are characterized by rapidly changing conditions and steep chemical and thermal gradients. Microorganisms living in these environments can take advantage of these changes by switching among metabolic pathways rather than specializing. We present reaction stoichiometry and rates for T. thermophila grown in a closed system both at ambient and elevated pressure (50 bars) that demonstrate substantial metabolic flexibility, shifting between up to 5 different sulfur cycling reactions over a 24 hour period. Based on the stoichiometry between S2O3 consumed and SO4 produced, three reactions are sulfur oxidation and two are disproportionation, which has not previously been demonstrated for Thiomicrospira strains. Reactants include S2O3, elemental S (both polymeric S chains and S8 rings), HS-, and O2, while products include polymeric elemental S, SO4, HS-, and polysulfides. The presence of μmolal concentrations of HS- has been confirmed during the time series only when stoichiometry predicts disproportionation. Production of HS- in the presence of elemental S results in abiotic conversion to polysulfides, keeping the sulfide concentrations low in solution. The transition from oxidation to disproportionation appears to be triggered by a depletion in dissolved oxygen and the rate of reaction is a second order function of S2O3 and O2 concentrations. Growth was tested at conditions spanning their pH tolerance (5.0 - 8.0) using a citrate buffer (pH 5.0), unbuffered media (initial pH 7.0), and Tris buffer (pH 8.0). The highest rates are observed at pH 8.0 with rates decreasing as a function of pH. The lowest rate occurs at pH 5.0 and exhibits pseudo-first order behavior over a 24 hour period, likely due to a long lag and very slow growth. Repeat injections after the culture is acclimated to the experimental conditions result in very high pseudo-first order rates due to rapid consumption of

  17. Enhanced metabolic versatility of planktonic sulfur-oxidizing γ-proteobacteria in an oxygen-deficient coastal ecosystem

    Directory of Open Access Journals (Sweden)

    Alejandro A. Murillo

    2014-07-01

    Full Text Available Sulfur-oxidizing Gamma-proteobacteria are abundant in marine oxygen-deficient waters, and appear to play a key role in a previously unrecognized cryptic sulfur cycle. Metagenomic analyses of members of the uncultured SUP05 lineage in the Canadian seasonally anoxic fjord Saanich Inlet (SI, hydrothermal plumes in the Guaymas Basin (GB and single cell genomics analysis of two ARCTIC96BD-19 representatives from the South Atlantic Sub-Tropical Gyre (SASG have shown them to be metabolically versatile. However, SI and GB SUP05 bacteria seem to be obligate chemolithoautotrophs, whereas ARCTIC96BD-19 has the genetic potential for aerobic respiration. Here, we present results of a metagenomic analysis of sulfur-oxidizing Gamma-proteobacteria (GSO, closely related to the SUP05/ARCTIC96BD-19 clade, from a coastal ecosystem in the eastern South Pacific (ESP. This ecosystem experiences seasonal anoxia and accumulation of nitrite and ammonium at depth, with a corresponding increase in the abundance of GSO representatives. The ESP-GSOs appear to have a significantly different gene complement than those from Saanich Inlet, Guaymas Basin and SASG. Genomic analyses of de novo assembled contigs indicate the presence of a complete aerobic respiratory complex based on the cytochrome bc1 oxidase. Furthermore, they appear to encode a complete TCA cycle and several transporters for dissolved organic carbon species, suggesting a mixotrophic lifestyle. Thus, the success of sulfur-oxidizing Gamma-proteobacteria in oxygen-deficient marine ecosystems appears due not only to their previously recognized anaerobic metabolic versatility, but also to their capacity to function under aerobic conditions using different carbon sources. Finally, members of ESP-GSO cluster also have the genetic potential for reducing nitrate to ammonium based on the nirBD genes, and may therefore facilitate a tighter coupling of the nitrogen and sulfur cycles in oxygen-deficient waters.

  18. Isolation and characterization of a sulfur-oxidizing chemolithotroph growing on crude oil under anaerobic conditions.

    Science.gov (United States)

    Kodama, Yumiko; Watanabe, Kazuya

    2003-01-01

    Molecular approaches have shown that a group of bacteria (called cluster 1 bacteria) affiliated with the epsilon subclass of the class Proteobacteria constituted major populations in underground crude-oil storage cavities. In order to unveil their physiology and ecological niche, this study isolated bacterial strains (exemplified by strain YK-1) affiliated with the cluster 1 bacteria from an oil storage cavity at Kuji in Iwate, Japan. 16S rRNA gene sequence analysis indicated that its closest relative was Thiomicrospira denitrificans (90% identity). Growth experiments under anaerobic conditions showed that strain YK-1 was a sulfur-oxidizing obligate chemolithotroph utilizing sulfide, elemental sulfur, thiosulfate, and hydrogen as electron donors and nitrate as an electron acceptor. Oxygen also supported its growth only under microaerobic conditions. Strain YK-1 could not grow on nitrite, and nitrite was the final product of nitrate reduction. Neither sugars, organic acids (including acetate), nor hydrocarbons could serve as carbon and energy sources. A typical stoichiometry of its energy metabolism followed an equation: S(2-) + 4NO(3)(-) --> SO(4)(2-) + 4NO(2)(-) (Delta G(0) = -534 kJ mol(-1)). In a difference from other anaerobic sulfur-oxidizing bacteria, this bacterium was sensitive to NaCl; growth in medium containing more than 1% NaCl was negligible. When YK-1 was grown anaerobically in a sulfur-depleted inorganic medium overlaid with crude oil, sulfate was produced, corresponding to its growth. On the contrary, YK-1 could not utilize crude oil as a carbon source. These results suggest that the cluster 1 bacteria yielded energy for growth in oil storage cavities by oxidizing petroleum sulfur compounds. Based on its physiology, ecological interactions with other members of the groundwater community are discussed.

  19. Sulfur equilibrium desulfurization of sulfur containing products of combustion

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Abichandani, J.S.

    1990-01-01

    This patent describes the method for the combustion of a carbon- and sulfur-containing fuel for substantially reducing emission of gaseous sulfur compounds formed during combustion of the fuel in a combustion zone. The zone having one or more fuel inlets and one or more oxidizer inlets, and having a combustion products outlet spaced therefrom, and having one or more inorganic sorbent inlets downstream of the fuel inlet(s) and oxidizer inlet(s) and upstream of the combustion products outlet

  20. Graphene-wrapped sulfur nanospheres with ultra-high sulfur loading for high energy density lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ya; Guo, Jinxin; Zhang, Jun, E-mail: zhangjun@zjnu.cn; Su, Qingmei; Du, Gaohui, E-mail: gaohuidu@zjnu.edu.cn

    2015-01-01

    Graphical abstract: - Highlights: • A graphene-wrapped sulfur nanospheres composite with 91 wt% S is prepared. • It shows highly improved electrochemical performance as cathode for Li–S cell. • The PVP coating and conductive graphene minimize polysulfides dissolution. • The flexible coatings with void space accommodate the volume expansion of sulfur. - Abstract: Lithium–sulfur (Li–S) battery with high theoretical energy density is one of the most promising energy storage systems for electric vehicles and intermittent renewable energy. However, due to the poor conductivity of the active material, considerable weight of the electrode is occupied by the conductive additives. Here we report a graphene-wrapped sulfur nanospheres composite (S-nanosphere@G) with sulfur content up to 91 wt% as the high energy density cathode material for Li–S battery. The sulfur nanospheres with diameter of 400–500 nm are synthesized through a solution-based approach with the existence of polyvinylpyrrolidone (PVP). Then the sulfur nanospheres are uniformly wrapped by conductive graphene sheets through the electrostatic interaction between graphene oxide and PVP, followed by reducing of graphene oxide with hydrazine. The design of graphene wrapped sulfur nanoarchitecture provides flexible conductive graphene coating with void space to accommodate the volume expansion of sulfur and to minimize polysulfide dissolution. As a result, the S-nanosphere@G nanocomposite with 91 wt% sulfur shows a reversible initial capacity of 970 mA h g{sup −1} and an average columbic efficiency > 96% over 100 cycles at a rate of 0.2 C. Taking the total mass of electrode into account, the S-nanosphere@G composite is a promising cathode material for high energy density Li–S batteries.

  1. Evaluation of haloalkaliphilic sulfur-oxidizing microorganisms with potential application in the effluent treatment of the petroleum industry.

    Science.gov (United States)

    Olguín-Lora, P; Le Borgne, S; Castorena-Cortés, G; Roldán-Carrillo, T; Zapata-Peñasco, I; Reyes-Avila, J; Alcántara-Pérez, S

    2011-02-01

    Haloalkaliphilic sulfur-oxidizing mixed cultures for the treatment of alkaline-saline effluents containing sulfide were characterized and evaluated. The mixed cultures (IMP-PB, IMP-XO and IMP-TL) were obtained from Mexican alkaline soils collected in Puebla (PB), Xochimilco (XO) and Tlahuac (TL), respectively. The Ribosomal Intergenic Spacer Analysis (RISA) revealed bacteria related to Thioalkalibacterium and Thioalkalivibrio in IMP-XO and IMP-PB mixed cultures. Halomonas strains were detected in IMP-XO and IMP-TL. In addition, an uncultured Bacteroides bacterium was present in IMP-TL. Mixed cultures were evaluated at different pH and NaCl concentrations at 30°C. IMP-PB and IMP-TL expressed thiosulfate-oxidizing activity in the 7.5-10.5 pH range, whereas IMP-XO presented its maximal activity with 19.0 mg O₂ g (protein)⁻¹ min⁻¹, at pH 10.6; it was not affected by NaCl concentrations up to 1.7 M. In continuous culture, IMP-XO showed a growth rate of 15 day⁻¹, productivity of 433.4 mg(protein) l⁻¹ day⁻¹ and haloalkaliphilic sulfur-oxidizing activity was also detected up to 170 mM by means of N-methyl-diethanolamine (MDEA). Saline-alkaline soil samples are potential sources of haloalkaliphilic sulfur-oxidizing bacteria and the mixed cultures could be applied in the treatment of inorganic sulfur compounds in petroleum industry effluents under alkaline-saline conditions.

  2. The desulfurization mechanism of iron-manganese compound oxide desulfurizer for removal of COS from coal gas

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fang-fang; Zhao Hai; Zhang De-xiang; Gao Jin-sheng [East China University of Science and Technology. Shanghai (China). School of Resource and Environmental Engineering

    2008-02-15

    The sorbent, atmospheric and components of outlet gas were analyzed by mass spectra, XRD, SEM, EDS etc. Desulfurisation performance of sorbents is good at 240 - 400 {sup o}C, atmospheric pressure and space speed of 500 - 2,000 h {sup -1}. The possible mechanism of desulfurisation reactions was obtained by analyzing the reduction- adsorption-sulfidation process. Carbon oxysulfide (COS) was converted to H{sub 2}S by hydrogen in strongly reducing atmosphere firstly. Then H{sub 2}S was adsorbed on the surface of desulfurizers, reacted with active component and transformed metal sulfides and water. Efficiency of removal of carbonyl sulfur is better in an atmosphere without carbonaceous oxide than in one with it, under test conditions. The existence of carbonaceous oxide restrains hydrogenation and the hydrolytic process of COS, which leads to a higher concentration of COS in the outlet. It is shown that chemical conversion is the main pathway in the reaction system of COS. Hydrogenation is the main process in the removal of COS from syngas. COS is preferentially catalyzed with active components n desulfurization sorbents, and generates H{sub 2}S which is subsequently absorbed. 13 refs., 4 figs., 2 tabs.

  3. STUDY OF HYDROGEN SULFIDE REMOVAL FROM GROUNDWATER

    Directory of Open Access Journals (Sweden)

    T. Lupascu

    2013-06-01

    Full Text Available The process of the hydrogen sulfide removal from the underground water of the Hancesti town has been investigated. By oxygen bubbling through the water containing hydrogen sulfide, from the Hancesti well tube, sulfur is deposited in the porous structure of studied catalysts, which decreases their catalytic activity. Concomitantly, the process of adsorption / oxidation of hydrogen sulfide to sulfate take place. The kinetic research of the hydrogen sulfide removal from the Hancesti underground water, after its treatment by hydrogen peroxide, proves greater efficiency than in the case of modified carbonic adsorbents. As a result of used treatment, hydrogen sulfide is completely oxidized to sulfates

  4. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID REMOVAL

    Energy Technology Data Exchange (ETDEWEB)

    Gary M. Blythe

    2004-01-01

    The objective of this project has been to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The project was co-funded by the U.S. DOE National Energy Technology Laboratory under Cooperative Agreement DE-FC26-99FT40718, along with EPRI, the American Electric Power Company (AEP), FirstEnergy Corporation, the Tennessee Valley Authority, and Carmeuse North America. Sulfuric acid controls are becoming of increased interest for coal-fired power generating units for a number of reasons. In particular, sulfuric acid can cause plant operation problems such as air heater plugging and fouling, back-end corrosion, and plume opacity. These issues will likely be exacerbated with the retrofit of selective catalytic reduction (SCR) for NOX control, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project tested the effectiveness of furnace injection of four different magnesium-based or dolomitic alkaline sorbents on full-scale utility boilers. These reagents were tested during one- to two-week tests conducted on two FirstEnergy Bruce Mansfield Plant (BMP) units. One of the sorbents tested was a magnesium hydroxide slurry byproduct from a modified Thiosorbic{reg_sign} Lime wet flue gas desulfurization process. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercially available magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners. The other three reagents were injected as slurries through air-atomizing nozzles inserted through the front wall of the upper furnace. After completing the four one- to two-week tests, the most promising sorbents were selected for longer-term (approximately 25-day) full-scale tests on two different units. The longer-term tests were conducted to confirm sorbent effectiveness over extended operation on two

  5. Multiple-heteroatom-containing sulfur compounds in a high sulfur coal

    International Nuclear Information System (INIS)

    Winans, R.E.; Neill, P.H.

    1990-01-01

    Flash vacuum pyrolysis of a high sulfur coal has been combined with high resolution mass spectrometry yielding information on aromatic sulfur compounds containing an additional heteroatom. Sulfur emission from coal utilization is a critical problem and in order to devise efficient methods for removing organic sulfur, it is important to know what types of molecules contain sulfur. A high sulfur Illinois No. 6 bituminous coal (Argonne Premium Coal Sample No. 3) was pyrolyzed on a platinum grid using a quartz probe inserted into a modified all glass heated inlet system and the products characterized by high resolution mass spectrometry (HRMS). A significant number of products were observed which contained both sulfur and an additional heteroatom. In some cases two additional heteroatoms were observed. These results are compared to those found in coal extracts and liquefaction products

  6. Desulfurization of oxidized diesel using ionic liquids

    Science.gov (United States)

    Wilfred, Cecilia D.; Salleh, M. Zulhaziman M.; Mutalib, M. I. Abdul

    2014-10-01

    The extraction of oxidized sulfur compounds from diesel were carried out using ten types of ionic liquids consisting of different cation and anion i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazoium thiocyanate, 1-butyl-3-methylimidazoium dicyanamide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazoliumhexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, trioctylmethylammonium chloride, 1-propionitrile-3-butylimidazolium thiocyanate, 1-propionitrile-3-butylimidazolium dicyanamide and 1-butyl-6-methylquinolinium dicyanamide. The oxidation of diesel was successfully done using phosphotungstic acid as the catalyst, hydrogen peroxide (H2O2) as the oxidant and trioctylmethylammonium chloride as the phase transfer agent. The oxidation of diesel changes the sulfur compounds into sulfone which increases its polarity and enhances the ionic liquid's extraction performance. Result showed that ionic liquid [C4mquin][N(CN)2] performed the highest sulfur removal (91% at 1:5 diesel:IL ratio) compared to the others.

  7. 40 CFR 52.1881 - Control strategy: Sulfur oxides (sulfur dioxide).

    Science.gov (United States)

    2010-07-01

    ....0 pounds of sulfur dioxide per million BTU actual heat input for the coal-fired boiler and 0.4... BTU actual heat input for coal-fired boiler C exiting through stack 5. (3) 2.24 pounds of sulfur dioxide per million BTU acutal heat input for coal-fired boiler D exiting through stack 6. (E) In lieu of...

  8. SYNTHESIS OF SULFUR-BASED WATER TREATMENT AGENT FROM SULFUR DIOXIDE WASTE STREAMS

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Maohong Fan; Adrienne Cooper

    2002-10-01

    Absorption of sulfur dioxide from a simulated flue gas was investigated for the production of polymeric ferric sulfate (PFS), a highly effective coagulant useful in treatment of drinking water and wastewater. The reaction for PFS synthesis took place near atmospheric pressure and at temperatures of 30-80 C. SO{sub 2} removal efficiencies greater than 90% were achieved, with ferrous iron concentrations in the product less than 0.1%. A factorial analysis of the effect of temperature, oxidant dosage, SO{sub 2} concentration, and gas flow rate on SO{sub 2} removal efficiency was carried out, and statistical analyses are conducted. The solid PFS was also characterized with different methods. Characterization results have shown that PFS possesses both crystalline and non-crystalline structure. The kinetics of reactions among FeSO{sub 4} {center_dot} 7H{sub 2}O, NaHSO{sub 3} and NaClO{sub 3} was investigated. The PFS product was used in pilot-scale tests at a municipal water treatment facility and gave good results in removal of turbidity and superior results in removal of disinfection byproduct precursors (TOC, DOC, UV-254) when compared with equal doses of ferric chloride.

  9. Warm Cleanup of Coal-Derived Syngas: Multicontaminant Removal Process Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Spies, Kurt A.; Rainbolt, James E.; Li, Xiaohong S.; Braunberger, Beau; Li, Liyu; King, David L.; Dagle, Robert A.

    2017-02-15

    Warm cleanup of coal- or biomass-derived syngas requires sorbent and catalytic beds to protect downstream processes and catalysts from fouling. Sulfur is particularly harmful because even parts-per-million amounts are sufficient to poison downstream synthesis catalysts. Zinc oxide (ZnO) is a conventional sorbent for sulfur removal; however, its operational performance using real gasifier-derived syngas and in an integrated warm cleanup process is not well reported. In this paper, we report the optimal temperature for bulk desulfurization to be 450oC, while removal of sulfur to parts-per-billion levels requires a lower temperature of approximately 350oC. Under these conditions, we found that sulfur in the form of both hydrogen sulfide and carbonyl sulfide could be absorbed equally well using ZnO. For long-term operation, sorbent regeneration is desirable to minimize process costs. Over the course of five sulfidation and regeneration cycles, a ZnO bed lost about a third of its initial sulfur capacity, however sorbent capacity stabilized. Here, we also demonstrate, at the bench-scale, a process and materials used for warm cleanup of coal-derived syngas using five operations: 1) Na2CO3 for HCl removal, 2) regenerable ZnO beds for bulk sulfur removal, 3) a second ZnO bed for trace sulfur removal, 4) a Ni-Cu/C sorbent for multi-contaminant inorganic removal, and 5) a Ir-Ni/MgAl2O4 catalyst employed for ammonia decomposition and tar and light hydrocarbon steam reforming. Syngas cleanup was demonstrated through successful long-term performance of a poison-sensitive, Cu-based, water-gas-shift catalyst placed downstream of the cleanup process train. The tar reformer is an important and necessary operation with this particular gasification system; its inclusion was the difference between deactivating the water-gas catalyst with carbon deposition and successful 100-hour testing using 1 LPM of coal-derived syngas.

  10. Process for selected gas oxide removal by radiofrequency catalysts

    Science.gov (United States)

    Cha, Chang Y.

    1993-01-01

    This process to remove gas oxides from flue gas utilizes adsorption on a char bed subsequently followed by radiofrequency catalysis enhancing such removal through selected reactions. Common gas oxides include SO.sub.2 and NO.sub.x.

  11. One-Step Extraction of Antimony in Low Temperature from Stibnite Concentrate Using Iron Oxide as Sulfur-Fixing Agent

    Directory of Open Access Journals (Sweden)

    Yun Li

    2016-07-01

    Full Text Available A new process for one-step extraction of antimony in low temperature from stibnite concentrate by reductive sulfur-fixation smelting in sodium molten salt, using iron oxide as sulfur-fixing agent, was presented. The influences of molten salt addition and composition, ferric oxide dosage, smelting temperature and duration on extraction efficiency of antimony were investigated in details, respectively. The optimum conditions were determined as follows: 1.0 time stoichiometric requirement (α of mixed sodium salt (αsalt = 1.0, WNaCl:Wsalt = 40%, αFe2O3 = 1.0, Wcoke:Wstibnite = 40%, where W represents weight, smelting at 850 °C (1123 K for 60 min. Under the optimum conditions, the direct recovery rate of antimony can reach 91.48%, and crude antimony with a purity of 96.00% has been achieved. 95.31% of sulfur is fixed in form of FeS in the presence of iron oxide. Meanwhile, precious metals contained in stibnite concentrate are enriched and recovered comprehensively in crude antimony. In comparison to traditional antimony pyrometallurgical process, the smelting temperature of present process is reduced from 1150–1200 °C (1423–1473 K to 850–900 °C (1123–1173 K. Sulfur obtained in stibnite is fixed in FeS which avoids SO2 emission owing to the sulfur-fixing agent. Sodium salt can be regenerated and recycled in smelting system when the molten slag is operated to filter solid residue. The solid residue is subjected to mineral dressing operation to obtain iron sulfide concentrate which can be sold directly or roasted to regenerate into iron oxide.

  12. Development of enhanced sulfur rejection processes

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, R.H.; Luttrell, G.H.; Adel, G.T.; Richardson, P.E.

    1996-03-01

    Research at Virginia Tech led to the development of two complementary concepts for improving the removal of inorganic sulfur from many eastern U.S. coals. These concepts are referred to as Electrochemically Enhanced Sulfur Rejection (EESR) and Polymer Enhanced Sulfur Rejection (PESR) processes. The EESR process uses electrochemical techniques to suppress the formation of hydrophobic oxidation products believed to be responsible for the floatability of coal pyrite. The PESR process uses polymeric reagents that react with pyrite and convert floatable middlings, i.e., composite particles composed of pyrite with coal inclusions, into hydrophilic particles. These new pyritic-sulfur rejection processes do not require significant modifications to existing coal preparation facilities, thereby enhancing their adoptability by the coal industry. It is believed that these processes can be used simultaneously to maximize the rejection of both well-liberated pyrite and composite coal-pyrite particles. The project was initiated on October 1, 1992 and all technical work has been completed. This report is based on the research carried out under Tasks 2-7 described in the project proposal. These tasks include Characterization, Electrochemical Studies, In Situ Monitoring of Reagent Adsorption on Pyrite, Bench Scale Testing of the EESR Process, Bench Scale Testing of the PESR Process, and Modeling and Simulation.

  13. Solvent extraction of elemental sulfur from coal and a determination of its source using stable sulfur isotopes

    Science.gov (United States)

    Hackley, Keith C.; Buchanan, D.H.; Coombs, K.; Chaven, C.; Kruse, C.W.

    1990-01-01

    Hot tetrachloroethene (perchloroethylene, PCE) extracts significant amounts of elemental sulfur (So) from weathered coals but not from pristine coals. The objective of this study was to determine whether So extracted by PCE is an oxidation product of pyrite or whether it originates in some way from unstable, organically-bound sulfur. The isotopic composition of the PCE-extracted So was compared to the isotopic compositions of the pyritic and the organic sulfur in a coal. The So was shown to have an isotopic signature similar to the pyritic sulfur. Additionally, the isotopic differences observed between the pyritic, So and sulfatic sulfur were consistent with bacterial mediated oxidation of sulfide sulfur (pyrite) as the source of both the sulfatic and elemental sulfur. ?? 1990.

  14. Ammonia removal in electrochemical oxidation: Mechanism and pseudo-kinetics

    International Nuclear Information System (INIS)

    Li Liang; Liu Yan

    2009-01-01

    This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO 2 /Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode-liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl - . The oxidation rates of ammonia ranged from 1.0 to 12.3 mg N L -1 h -1 and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl - . About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N 2 in the produced gas. The rate at which Cl - lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl - concentration affected the constant of the pseudo zero-order kinetics, expressed by k = 0.0024[Cl - ] x j. The ammonia was reduced to less than 0.5 mg N L -1 after 2 h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements

  15. Surface characterization studies of walnut-shell biochar catalysts for simultaneously removing of organic sulfur from yellow phosphorus tail gas

    Science.gov (United States)

    Song, Xin; Li, Kai; Ning, Ping; Wang, Chi; Sun, Xin; Tang, Lihong; Ruan, Haotian; Han, Shuang

    2017-12-01

    The influences of different preparation conditions for surface characteristics on removing organic sulfur were studied. From BET, XRD, FTIR, DRIFTS, TG/DTA, CO2-TPD results, it can be seen that these preparation conditions had great influences on the pore structure, specific surface area, crystal structure and surface functional groups. The micropore volume, amorphous structure and alkalinity site strength played major roles in desulfurization process. H2S was oxidized by oxygen containing functional groups, such as sbnd COO, sbnd Cdbnd O. H2O molecule could be converted into some groups, such as sbnd CH and Csbnd OH groups, and promoted the hydrolysis reaction. The strong alkalinity site was the key factor for chemical adsorption and hydrolysis. H2O molecule, sbnd CH, Csbnd OH groups promoted the hydrolysis reaction and sbnd COO, sbnd Cdbnd O groups promoted the oxidation of H2S on the surface of WSB. Meanwhile, the main desulfurization process over WSB after carbonization was adsorption and it changed to hydrolysis reaction after activation on the surface of WSB. Furthermore, the reaction mechanism was investigated by DRIFTS measurement according to the change of surface functional groups.

  16. Plasma polymer-functionalized silica particles for heavy metals removal.

    Science.gov (United States)

    Akhavan, Behnam; Jarvis, Karyn; Majewski, Peter

    2015-02-25

    Highly negatively charged particles were fabricated via an innovative plasma-assisted approach for the removal of heavy metal ions. Thiophene plasma polymerization was used to deposit sulfur-rich films onto silica particles followed by the introduction of oxidized sulfur functionalities, such as sulfonate and sulfonic acid, via water-plasma treatments. Surface chemistry analyses were conducted by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Electrokinetic measurements quantified the zeta potentials and isoelectric points (IEPs) of modified particles and indicated significant decreases of zeta potentials and IEPs upon plasma modification of particles. Plasma polymerized thiophene-coated particles treated with water plasma for 10 min exhibited an IEP of less than 3.5. The effectiveness of developed surfaces in the adsorption of heavy metal ions was demonstrated through copper (Cu) and zinc (Zn) removal experiments. The removal of metal ions was examined through changing initial pH of solution, removal time, and mass of particles. Increasing the water plasma treatment time to 20 min significantly increased the metal removal efficiency (MRE) of modified particles, whereas further increasing the plasma treatment time reduced the MRE due to the influence of an ablation mechanism. The developed particulate surfaces were capable of removing more than 96.7% of both Cu and Zn ions in 1 h. The combination of plasma polymerization and oxidative plasma treatment is an effective method for the fabrication of new adsorbents for the removal of heavy metals.

  17. Use of liquid chromatography for measuring atmospheric sulfur dioxide and nitrogen oxide

    Energy Technology Data Exchange (ETDEWEB)

    Benova, E

    1973-02-01

    A literature search to ascertain the applicability of liquid chromatography to the analysis of atmospheric sulfur dioxide and various oxides of nitrogen is reported. Simple or enriched samples can be analyzed. Plastic bags are recommended for preparation of simple samples; and a table of 18 plastic materials, their manufacturers, and pollutants to which they are inert is provided. Enriched samples can be prepared in chromatographic columns by adsorption methods. Tables are provided listing carriers, stationary phase materials, temperatures, carrier liquids (helium or nitrogen), column dimensions, and other data recommended for chromatographic tests of SO/sub 2/ and NOx. Because of its reactivity and tendency to polymerize, sulfur trioxide should be reduced to SO/sub 2/ prior to analysis.

  18. X-ray spectral determination of chemical state of phosphorus and sulfur in anodic oxide films on niobium

    International Nuclear Information System (INIS)

    Bokij, L.P.; Kostikov, Yu.P.

    1989-01-01

    Chemical forms of phosphorus and sulfur in niobium oxide anodic film, obtained by electrochemical technique using niobium in H 2 SO 4 and H 3 PO 4 aqueous solutions, are determined using data on chemical shifts of X-ray emission lines. Films represent Nb 2 O 5(1-γ) (SO 4 ) 5γ and Nb 2 O 5(1-γ) (PO 4 ) 10γ/3 (γ -share of oxygen substituted by acid anion) composition oxosalts. Electrolyte role in formation of niobium anodic oxide structure and effect of phosphorus and sulfur compounds on anodic film conductivity are determined

  19. Danburite decomposition by sulfuric acid

    International Nuclear Information System (INIS)

    Mirsaidov, U.; Mamatov, E.D.; Ashurov, N.A.

    2011-01-01

    Present article is devoted to decomposition of danburite of Ak-Arkhar Deposit of Tajikistan by sulfuric acid. The process of decomposition of danburite concentrate by sulfuric acid was studied. The chemical nature of decomposition process of boron containing ore was determined. The influence of temperature on the rate of extraction of boron and iron oxides was defined. The dependence of decomposition of boron and iron oxides on process duration, dosage of H 2 SO 4 , acid concentration and size of danburite particles was determined. The kinetics of danburite decomposition by sulfuric acid was studied as well. The apparent activation energy of the process of danburite decomposition by sulfuric acid was calculated. The flowsheet of danburite processing by sulfuric acid was elaborated.

  20. An oxidative desulfurization method using ultrasound/Fenton's reagent for obtaining low and/or ultra-low sulfur diesel fuel

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yongchuan; Qi, Yutai [Department of Applied Chemistry, School of Science, Harbin Institute of Technology, Harbin 115001 (China); Zhao, Dezhi [Department of Petroleum Chemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Zhang, Huicheng [Fushun Research Institute of Petroleum and Petrochemicals of SINOPEC Corp., Fushun 113001 (China)

    2008-10-15

    The total development trend in the world is towards continuously lower of sulfur content as a quality standard of diesel fuels. Integrating of an oxidative desulfurization unit with a conventional hydrotreating unit can bring benefits to producing low and/or ultra-low sulfur diesel fuels. Using the hydrotreated Middle East diesel fuel as a feedstock, four processes of the oxidative desulfurization have been studied: a hydrogen peroxide-acetic acid system and a Fenton's reagent system both without/with ultrasound. Results showed that the oxidative desulfurization reaction mechanics fitted apparent first-order kinetics. The addition of Fenton's reagent could enhance the oxidative desulfurization efficiency for diesel fuels and sono-oxidation treatment in combination with Fenton's reagent shows a good synergistic effect. Under our best operating condition for the oxidative desulfurization: temperature 313 K, ultrasonic power 200 W, ultrasonic frequency 28 kHz, Fe{sup 2+}/H{sub 2}O{sub 2} 0.05 mol/mol, pH 2.10 in aqueous phase and reaction time 15 min, the sulfur content in the diesel fuels was decreased from 568.75 {mu}g/g to 9.50 {mu}g/g. (author)

  1. Solvent extraction of elemental sulfur from coal and a determination of its source using stable sulfur isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, K.C.; Buchanan, D.H.; Coombs, K.; Chaven, C.; Kruse, C.W. (Eastern Illinois University, Charleston, IL (USA). Chemistry Dept.)

    1990-01-01

    Hot tetrachloroethene (perchloroethylen PCE) extracts significant amounts of elemental sulfur (S{sup o}) from weathered coals but not from pristine coals. The objective of this study was to determine whether S{sup o} extracted by PCE is an oxidation product of pyrite or whether it originates in some way from unstable, organically-bound sulfur. The isotopic composition of the PCE-extracted S{sup o} was compared to the isotopic compositions of the pyritic and the organic sulfur in a coal. The S{sup o} was shown to have an isotopic signature similar to the pyritic sulfur. Additionally, the isotopic differences observed between the pyritic, S{sup o} and sulfatic sulfur were consistent with bacterial mediated oxidation of sulfide sulfur (pyrite) as the source of both the sulfatic and elemental sulfur. 21 refs., 2 tabs.

  2. Sulfur cycle

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.

    Microbes, especially bacteria, play an important role in oxidative and reductive cycle of sulfur. The oxidative part of the cycle is mediated by photosynthetic bacteria in the presence of light energy and chemosynthetic forms in the absence of light...

  3. Process using sorbents for the removal of SOx from flue gas

    International Nuclear Information System (INIS)

    Pinnavaia, T.J.; Amareskera, J.; Polansky, C.A.

    1992-01-01

    This patent describes a process for removing the SO x components from a flue gas stream containing oxygen, sulfur dioxide and sulfur trioxide from the combustion of coal from a coal-fired boiler which comprises combusting the coal in the boiler to provide the flue gas stream and contacting the the gas stream with a heated sorbent composition at 400 degrees to 1000 degrees C wherein the the sorbent before being heated is selected from the group consisting of a layered double hydroxide composition of formula: [M 1-x II M x III (OH) 2 ](A n- ) x/n · yH 2 O wherein M II is a divalent metal cation and M III is a trivalent metal cation selected from the group consisting of Group IIA. IIB and IIIA metals as the cation which form metal oxides and which are capable of reacting with SO 2 to form metal sulfites and SO 3 to form metal sulfates, A is an interlayer anion of charge n- which comprises at least one metal atoms selected from the group consisting of main group metals and transition metals which provide oxidation of sulfur dioxide to sulfur trioxide in an amount sufficient that the layered double hydroxide structure promotes the oxidation of the sulfur dioxide to the sulfur trioxide at the combustion conditions within the coal-fired boiler, wherein y is moles of water

  4. The surface evolution of La0.4Sr0.6TiO3+δ anode in solid oxide fuel cells: Understanding the sulfur-promotion effect

    Science.gov (United States)

    Yan, Ning; Zanna, Sandrine; Klein, Lorena H.; Roushanafshar, Milad; Amirkhiz, Babak S.; Zeng, Yimin; Rothenberg, Gadi; Marcus, Philippe; Luo, Jing-Li

    2017-03-01

    The ideal solid oxide fuel cells (SOFCs) can be powered by readily available hydrocarbon fuels containing impurities. While this is commonly recognized as a key advantage of SOFC, it also, together with the elevated operating temperature, becomes the main barrier impeding the in-situ or operando investigations of the anode surface chemistry. Here, using a well-designed quenching experiment, we managed to characterize the near-surface structure of La0.4Sr0.6TiO3+δ (LST) anode in SOFCs fuelled by H2S-containing methane. This new method enabled us to clearly observe the surface amorphization and sulfidation of LST under simulated SOFC operating conditions. The ∼1 nm-thick two dimensional sulfur-adsorbed layer was on top of the disordered LST, containing -S, -SH and elemental sulfur species. In SOFC test, such "poisoned" anode showed increased performances: a ten-fold enhanced power density enhancement (up to 30 mW cm-2) and an improved open circuit voltage (from 0.69 V to 1.17 V). Moreover, its anodic polarization resistance in methane decreased to 21.53 Ω cm2, a difference of 95% compared with the sulfur-free anode. Control experiments confirmed that once the adsorbed sulfur species were removed electrochemically, methane conversion slowed down simultaneously till full stop.

  5. Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria (Final Report, Sep 2008)

    Science.gov (United States)

    EPA announced the availability of the final report, Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria final assessment. This report represents a concise synthesis and evaluation of the most policy-relevant science and will ultimately provide the scien...

  6. Development of a portable, modular unit for the optimization of ultrasound-assisted oxidative desulfurization of diesel

    Science.gov (United States)

    Wan, Meng-Wei

    Due to the stringent rules requiring ultra-low sulfur content in diesel fuels, it is necessary to develop alternative methods of desulfurization of fossil fuel derived oil, such as diesel. Current technology is not sufficient to solve this problem. Ultrasound applied to oxidative desulfurization which combined three complementary techniques: ultrasonication, phase transfer catalysis (PTC) and transition metal catalyzed oxidation, has accomplished high sulfur removal in a short contact time at ambient temperature and atmospheric pressure. This research has successfully demonstrated that the higher oxidation efficiency of BT to BTO and free of any by-products by using tetraoctylammonium fluoride as phase transfer agent. The oxidation rate of BT to BTO increased with increasing the carbon chain length of QAS cations. Under the same length of carbon chain, the oxidation rate of BT to BTO increased with decreasing the molecular size of QAS anions. Moreover, for diesel fuels containing various levels of sulfur content, UAOD process followed by solvent extraction has demonstrated that the sulfur reduction can reach above 95 % removal efficiency or final sulfur content below 15 ppm in mild condition. For large-scale commercial production, this research has successfully developed and operated a continuous desulfurization unit, which consists of a sonoractor, an RF amplifier, a function generator, a pretreatment tank, and a pipeline system. A single unit only needed 2' x 4' x 1' space for installation. The results indicated that the remarkable 92% removal efficiency for the sulfur in marine logistic diesel, even at a treatment rate as high as 25 lb/hour which is approximately 2 barrels per day. Therefore, this sonoreactor demonstrated the feasibility of large-scale operation even in a relatively small installation with low capital investment and maintenance cost. It also ensures the safety considerations by operating with diluted hydrogen peroxide under ambient temperature

  7. Characteristics of activated carbon remove sulfur particles against smog.

    Science.gov (United States)

    Ge, Shengbo; Liu, Zhenling; Furuta, Yuzo; Peng, Wanxi

    2017-09-01

    Sulfur particles, which could cause diseases, were the main powder of smog. And activated carbon had the very adsorption characteristics. Therefore, five sulfur particles were adsorbed by activated carbon and were analyzed by FT-IR. The optimal adsorption time were 120 min of Na 2 SO 3 , 120 min of Na 2 S 2 O 8 , 120 min of Na 2 SO 4 , 120 min of Fe 2 (SO 4 ) 3 and 120 min of S. FT-IR spectra showed that activated carbon had the eight characteristic absorption of S-S stretch, H 2 O stretch, O-H stretch, -C-H stretch, conjugated C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 O stretch or CC stretch, CH 2 bend, C-O stretch and acetylenic C-H bend vibrations at 3850 cm -1 , 3740 cm -1 , 3430 cm -1 , 2920 cm -1 , 1630 cm -1 , 1390 cm -1 , 1110 cm -1 and 600 cm -1 , respectively. For Na 2 SO 3 , the peaks at 2920 cm -1 , 1630 cm -1 , 1390 cm -1 and 1110 cm -1 achieved the maximum at 20 min. For Na 2 S 2 O 8 , the peaks at 3850 cm -1 , 3740 cm -1 and 2920 cm -1 achieved the maximum at 60 min. The peaks at 1390 cm -1 , 1110 cm -1 and 600 cm -1 achieved the maximum at 40 min. For Na 2 SO 4 , the peaks at 3430 cm -1 , 2920 cm -1 , 1630 cm -1 , 1390 cm -1 , 1110 cm -1 and 600 cm -1 achieved the maximum at 60 min. For Fe 2 (SO 4 ) 3 , the peaks at 1390 cm -1 , 1110 cm -1 and 600 cm -1 achieved the maximum at 20 min. For S, the peaks at 1630 cm -1 , 1390 cm -1 and 600 cm -1 achieved the maximum at 120 min. It provided that activated carbon could remove sulfur particles from smog air to restrain many anaphylactic diseases.

  8. A MnO2/Graphene Oxide/Multi-Walled Carbon Nanotubes-Sulfur Composite with Dual-Efficient Polysulfide Adsorption for Improving Lithium-Sulfur Batteries.

    Science.gov (United States)

    Li, Yong; Ye, Daixin; Liu, Wen; Shi, Bin; Guo, Rui; Zhao, Hongbin; Pei, Haijuan; Xu, Jiaqiang; Xie, Jingying

    2016-10-26

    Lithium-sulfur batteries can potentially be used as a chemical power source because of their high energy density. However, the sulfur cathode has several shortcomings, including fast capacity attenuation, poor electrochemical activity, and low Coulombic efficiency. Herein, multi-walled carbon nanotubes (CNTs), graphene oxide (GO), and manganese dioxide are introduced to the sulfur cathode. A MnO 2 /GO/CNTs-S composite with a unique three-dimensional (3D) architecture was synthesized by a one-pot chemical method and heat treatment approach. In this structure, the innermost CNTs work as a conducting additive and backbone to form a conducting network. The MnO 2 /GO nanosheets anchored on the sidewalls of CNTs have a dual-efficient absorption capability for polysulfide intermediates as well as afford adequate space for sulfur loading. The outmost nanosized sulfur particles are well-distributed on the surface of the MnO 2 /GO nanosheets and provide a short transmission path for Li + and the electrons. The sulfur content in the MnO 2 /GO/CNTs-S composite is as high as 80 wt %, and the as-designed MnO 2 /GO/CNTs-S cathode displays excellent comprehensive performance. The initial specific capacities are up to 1500, 1300, 1150, 1048, and 960 mAh g -1 at discharging rates of 0.05, 0.1, 0.2, 0.5, and 1 C, respectively. Moreover, the composite cathode shows a good cycle performance: the specific capacity remains at 963.5 mAh g -1 at 0.2 C after 100 cycles when the area density of sulfur is 2.8 mg cm -2 .

  9. Sulfite-oxido-reductase is involved in the oxidation of sulfite in Desulfocapsa sulfoexigens during disproportionation of thiosulfate and elemental sulfur.

    Science.gov (United States)

    Frederiksen, Trine-Maria; Finster, Kai

    2003-06-01

    The enzymatic pathways of elemental sulfur and thiosulfate disproportionation were investigated using cell-free extract of Desulfocapsa sulfoexigens. Sulfite was observed to be an intermediate in the metabolism of both compounds. Two distinct pathways for the oxidation of sulfite have been identified. One pathway involves APS reductase and ATP sulfurylase and can be described as the reversion of the initial steps of the dissimilatory sulfate reduction pathway. The second pathway is the direct oxidation of sulfite to sulfate by sulfite oxidoreductase. This enzyme has not been reported from sulfate reducers before. Thiosulfate reductase, which cleaves thiosulfate into sulfite and sulfide, was only present in cell-free extract from thiosulfate disproportionating cultures. We propose that this enzyme catalyzes the first step in thiosulfate disproportionation. The initial step in sulfur disproportionation was not identified. Dissimilatory sulfite reductase was present in sulfur and thiosulfate disproportionating cultures. The metabolic function of this enzyme in relation to elemental sulfur or thiosulfate disproportionation was not identified. The presence of the uncouplers HQNO and CCCP in growing cultures had negative effects on both thiosulfate and sulfur disproportionation. CCCP totally inhibited sulfur disproportionation and reduced thiosulfate disproportionation by 80% compared to an unamended control. HQNO reduced thiosulfate disproportionation by 80% and sulfur disproportionation by 90%.

  10. Removal of mercury from coal via a microbial pretreatment process

    Science.gov (United States)

    Borole, Abhijeet P [Knoxville, TN; Hamilton, Choo Y [Knoxville, TN

    2011-08-16

    A process for the removal of mercury from coal prior to combustion is disclosed. The process is based on use of microorganisms to oxidize iron, sulfur and other species binding mercury within the coal, followed by volatilization of mercury by the microorganisms. The microorganisms are from a class of iron and/or sulfur oxidizing bacteria. The process involves contacting coal with the bacteria in a batch or continuous manner. The mercury is first solubilized from the coal, followed by microbial reduction to elemental mercury, which is stripped off by sparging gas and captured by a mercury recovery unit, giving mercury-free coal. The mercury can be recovered in pure form from the sorbents via additional processing.

  11. The GC/AED studies on the reactions of sulfur mustard with oxidants

    International Nuclear Information System (INIS)

    Popiel, StanisIaw; Witkiewicz, Zygfryd; Szewczuk, Aleksander

    2005-01-01

    A gas chromatograph coupled with an atomic emission detector was used to identify and to determine the products formed on oxidation of sulfur mustard. The oxidation rate and the resulting oxidates were studied in relation to oxidant type and reaction medium parameters. Hydrogen peroxide, sodium hypochlorite, sodium perborate, potassium monopercarbonate, ammonium peroxydisulfate, potassium peroxymonosulfate (oxone), and tert-butyl peroxide were used as oxidants. Oxidations were run in aqueous media or in solvents of varying polarities. The oxidation rate was found to be strongly related to oxidant type: potassium peroxymonosulfate (oxone) and sodium hypochlorite were fast-acting oxidants; sodium perborate, hydrogen peroxide, ammonium peroxydisulfate, and sodium monopercarbonate were moderate oxidants; tert-butyl peroxide was the slowest-acting oxidant. In non-aqueous solvents, the oxidation rate was strongly related to solvent polarity. The higher the solvent polarity, the faster the oxidation rate. In the acid and neutral media, the mustard oxidation rates were comparable. In the alkaline medium, oxidation was evidently slower. A suitable choice of the initial oxidant-to-mustard concentration ratio allowed to control the type of the resulting mustard oxidates. As the pH of the reaction medium was increased, the reaction of elimination of hydrogen chloride from mustard oxidates becomes more and more intensive

  12. Regeneration of sulfated metal oxides and carbonates

    Science.gov (United States)

    Hubble, Bill R.; Siegel, Stanley; Cunningham, Paul T.

    1978-03-28

    Alkali metal or alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate found in dolomite or limestone are employed for removal of sulfur dioxide from combustion exhaust gases. The sulfated carbonates are regenerated to oxides through use of a solid-solid reaction, particularly calcium sulfide with calcium sulfate to form calcium oxide and sulfur dioxide gas. The regeneration is performed by contacting the sulfated material with a reductant gas such as hydrogen within an inert diluent to produce calcium sulfide in mixture with the sulfate under process conditions selected to permit the sulfide-sulfate, solid-state reaction to occur.

  13. Degradation of solid oxide fuel cell metallic interconnects in fuels containing sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Ziomek-Moroz, M.; Hawk, Jeffrey A.

    2005-01-01

    Hydrogen is the main fuel for all types of fuel cells except direct methanol fuel cells. Hydrogen can be generated from all manner of fossil fuels, including coal, natural gas, diesel, gasoline, other hydrocarbons, and oxygenates (e.g., methanol, ethanol, butanol, etc.). Impurities in the fuel can cause significant performance problems and sulfur, in particular, can decrease the cell performance of fuel cells, including solid oxide fuel cells (SOFC). In the SOFC, the high (800-1000°C) operating temperature yields advantages (e.g., internal fuel reforming) and disadvantages (e.g., material selection and degradation problems). Significant progress in reducing the operating temperature of the SOFC from ~1000 ºC to ~750 ºC may allow less expensive metallic materials to be used for interconnects and as balance of plant (BOP) materials. This paper provides insight on the material performance of nickel, ferritic steels, and nickel-based alloys in fuels containing sulfur, primarily in the form of H2S, and seeks to quantify the extent of possible degradation due to sulfur in the gas stream.

  14. Some information needs for air quality modeling. [Environmental effects of sulfur compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hill, F B

    1975-09-01

    The following topics were considered at the workshop: perturbation of the natural sulfur cycle by human activity; ecosystem responses to a given environmental dose of sulfur compounds; movement of sulfur compounds within the atmosphere; air quality models; contribution of biogenic sulfur compounds to atmospheric burden of sulfur; production of acid rain from sulfur dioxide; meteorological processes; and rates of oxidation of SO/sub 2/ via direct photo-oxidation, oxidation resulting from photo-induced free radical chemistry, and catalytic oxidation in cloud droplets and on dry particles. (HLW)

  15. Oxidation of sulfur and nitrogen oxides by pulse corona discharge

    International Nuclear Information System (INIS)

    Amirov, R.H.; Desiaterik, Yu.N.; Filimonova, E.A.; Zhelezniak, M.B.; Chae, J.O.

    1996-01-01

    The NO x and SO 2 removal efficiency of the corona reactor has been measured both with and without ammonia addition to the gas stream. Experimental conditions are described. The dependence of NO and SO 2 removal efficiency from flow rate and initial pollutant concentrations were measured. One test with fixed amount of the inputted energy per the unit of SO 2 but with different initial concentration have been made. It is found that increasing of the initial concentration from 200 ppm to 700 ppm can enlarge the removal efficiency by factor 2.5. Some tests were carried out with both pollutant gases SO 2 and NO simultaneously. An efficiency on the SO 2 removal of 96% and on the NO removal 70% in pulse corona have been achieved with ammonia addition when SO 2 initial concentration was 480 ppm and the NO initial concentration was 230 ppm. A numerical model for NO and SO 2 oxidation in homogeneous gas flow has been developed. The flow contains cold (T = 300-400 K) background components N 2 , CO 2 , H 2 O, O 2 and impurities SO 2 , NO x , CO. A source of chemically active species is an electrical streamer discharge of corona type. (authors)

  16. Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

    DEFF Research Database (Denmark)

    Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

    1997-01-01

    Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de......NOx'ed flue gas. The vanadium (IV) compound K4(VO)3(SO4)5 precipitated during all the investigated conditions hence causing catalyst deactivation. Hysteresis behavior of both the catalytic activity and the V(IV) content was observed during reheating....

  17. Elementary sulfur in effluent from denitrifying sulfide removal process as adsorbent for zinc(II).

    Science.gov (United States)

    Chen, Chuan; Zhou, Xu; Wang, Aijie; Wu, Dong-hai; Liu, Li-hong; Ren, Nanqi; Lee, Duu-Jong

    2012-10-01

    The denitrifying sulfide removal (DSR) process can simultaneously convert sulfide, nitrate and organic compounds into elementary sulfur (S(0)), di-nitrogen gas and carbon dioxide, respectively. However, the S(0) formed in the DSR process are micro-sized colloids with negatively charged surface, making isolation of S(0) colloids from other biological cells and metabolites difficult. This study proposed the use of S(0) in DSR effluent as a novel adsorbent for zinc removal from wastewaters. Batch and continuous tests were conducted for efficient zinc removal with S(0)-containing DSR effluent. At pHremoval rates of zinc(II) were increased with increasing pH. The formed S(0) colloids carried negative charge onto which zinc(II) ions could be adsorbed via electrostatic interactions. The zinc(II) adsorbed S(0) colloids further enhanced coagulation-sedimentation efficiency of suspended solids in DSR effluents. The DSR effluent presents a promising coagulant for zinc(II) containing wastewaters. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Prevention of formation of acid drainage from high-sulfur coal refuse by inhibition of iron- and sulfur-oxidizing microorganisms. 1. Preliminary experiments in controlled shaken flasks

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, P.R.

    1987-01-01

    Changes of pH and sulfate concentration in high-sulfur coal refuse slurries are used as measurements of microbial pyrite oxidation in the laboratory. Sodium lauryl sulfate (SLS), alkylbenzene sulfonate (ABS), benzoic acid (BZ) and combinations of SLS plus BZ and ABS plus BZ effectively inhibited formation of sulfate and acid when added in concentrations greater than 50 mg/l to inoculated 20 or 30% coal refuse slurries. Here 25 mg/l concentrations of SLS, ABS and ABS plus BZ stimulated acid production. Formic, hexanoic, oxalic, propionic, and pyruvic acids at 0.1% concentrations were also effective inhibitors. Four different lignin sulfonates were only slightly effective inhibitors at 0.1% concentrations. It was concluded that acid formation resulting from microbial oxidation in high-sulfur coal refuse can be inhibited. 22 references.

  19. Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments

    Directory of Open Access Journals (Sweden)

    François eThomas

    2014-06-01

    Full Text Available Salt marshes are highly productive ecosystems hosting an intense sulfur (S cycle, yet little is known about S-oxidizing microorganisms in these ecosystems. Here, we studied the diversity and transcriptional activity of S-oxidizers in salt marsh sediments colonized by the plant Spartina alterniflora, and assessed variations with sediment depth and small-scale compartments within the rhizosphere. We combined next-generation amplicon sequencing of 16S rDNA and rRNA libraries with phylogenetic analyses of marker genes for two S-oxidation pathways (soxB and rdsrAB. Gene and transcript numbers of soxB and rdsrAB phylotypes were quantified simultaneously, using newly designed (RT-qPCR assays. We identified a diverse assemblage of S-oxidizers, with Chromatiales and Thiotrichales being dominant. The detection of transcripts from S-oxidizers was mostly confined to the upper 5 cm sediments, following the expected distribution of root biomass. A common pool of species dominated by Gammaproteobacteria transcribed S-oxidation genes across roots, rhizosphere, and surrounding sediment compartments, with rdsrAB transcripts prevailing over soxB. However, the root environment fine-tuned the abundance and transcriptional activity of the S-oxidizing community. In particular, the global transcription of soxB was higher on the roots compared to mix and rhizosphere samples. Furthermore, the contribution of Epsilonproteobacteria-related S-oxidizers tended to increase on Spartina roots compared to surrounding sediments. These data shed light on the under-studied oxidative part of the sulfur cycle in salt marsh sediments and indicate small-scale heterogeneities are important factors shaping abundance and potential activity of S-oxidizers in the rhizosphere.

  20. Peatland Acidobacteria with a dissimilatory sulfur metabolism.

    Science.gov (United States)

    Hausmann, Bela; Pelikan, Claus; Herbold, Craig W; Köstlbacher, Stephan; Albertsen, Mads; Eichorst, Stephanie A; Glavina Del Rio, Tijana; Huemer, Martin; Nielsen, Per H; Rattei, Thomas; Stingl, Ulrich; Tringe, Susannah G; Trojan, Daniela; Wentrup, Cecilia; Woebken, Dagmar; Pester, Michael; Loy, Alexander

    2018-02-23

    Sulfur-cycling microorganisms impact organic matter decomposition in wetlands and consequently greenhouse gas emissions from these globally relevant environments. However, their identities and physiological properties are largely unknown. By applying a functional metagenomics approach to an acidic peatland, we recovered draft genomes of seven novel Acidobacteria species with the potential for dissimilatory sulfite (dsrAB, dsrC, dsrD, dsrN, dsrT, dsrMKJOP) or sulfate respiration (sat, aprBA, qmoABC plus dsr genes). Surprisingly, the genomes also encoded DsrL, which so far was only found in sulfur-oxidizing microorganisms. Metatranscriptome analysis demonstrated expression of acidobacterial sulfur-metabolism genes in native peat soil and their upregulation in diverse anoxic microcosms. This indicated an active sulfate respiration pathway, which, however, might also operate in reverse for dissimilatory sulfur oxidation or disproportionation as proposed for the sulfur-oxidizing Desulfurivibrio alkaliphilus. Acidobacteria that only harbored genes for sulfite reduction additionally encoded enzymes that liberate sulfite from organosulfonates, which suggested organic sulfur compounds as complementary energy sources. Further metabolic potentials included polysaccharide hydrolysis and sugar utilization, aerobic respiration, several fermentative capabilities, and hydrogen oxidation. Our findings extend both, the known physiological and genetic properties of Acidobacteria and the known taxonomic diversity of microorganisms with a DsrAB-based sulfur metabolism, and highlight new fundamental niches for facultative anaerobic Acidobacteria in wetlands based on exploitation of inorganic and organic sulfur molecules for energy conservation.

  1. Ag@Ni core-shell nanowire network for robust transparent electrodes against oxidation and sulfurization.

    Science.gov (United States)

    Eom, Hyeonjin; Lee, Jaemin; Pichitpajongkit, Aekachan; Amjadi, Morteza; Jeong, Jun-Ho; Lee, Eungsug; Lee, Jung-Yong; Park, Inkyu

    2014-10-29

    Silver nanowire (Ag NW) based transparent electrodes are inherently unstable to moist and chemically reactive environment. A remarkable stability improvement of the Ag NW network film against oxidizing and sulfurizing environment by local electrodeposition of Ni along Ag NWs is reported. The optical transmittance and electrical resistance of the Ni deposited Ag NW network film can be easily controlled by adjusting the morphology and thickness of the Ni shell layer. The electrical conductivity of the Ag NW network film is increased by the Ni coating via welding between Ag NWs as well as additional conductive area for the electron transport by electrodeposited Ni layer. Moreover, the chemical resistance of Ag NWs against oxidation and sulfurization can be dramatically enhanced by the Ni shell layer electrodeposited along the Ag NWs, which provides the physical barrier against chemical reaction and diffusion as well as the cathodic protection from galvanic corrosion. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Method of removing niobium from uranium-niobium alloy

    International Nuclear Information System (INIS)

    Pollock, E.N.; Schlier, D.S.; Shinopulos, G.

    1992-01-01

    This patent describes a method of removing niobium from a uranium-niobium alloy. It comprises dissolving the uranium-niobium alloy metal pieces in a first aqueous solution containing an acid selected from the group consisting of hydrochloric acid and sulfuric acid and fluoboric acid as a catalyst to provide a second aqueous solution, which includes uranium (U +4 ), acid radical ions, the acids insolubles including uranium oxides and niobium oxides; adding nitric acid to the insolubles to oxidize the niobium oxides to yield niobic acid and to complete the solubilization of any residual uranium; and separating the niobic acid from the nitric acid and solubilized uranium

  3. Rational Design of a Water-Storable Hierarchical Architecture Decorated with Amorphous Barium Oxide and Nickel Nanoparticles as a Solid Oxide Fuel Cell Anode with Excellent Sulfur Tolerance.

    Science.gov (United States)

    Song, Yufei; Wang, Wei; Ge, Lei; Xu, Xiaomin; Zhang, Zhenbao; Julião, Paulo Sérgio Barros; Zhou, Wei; Shao, Zongping

    2017-11-01

    Solid oxide fuel cells (SOFCs), which can directly convert chemical energy stored in fuels into electric power, represent a useful technology for a more sustainable future. They are particularly attractive given that they can be easily integrated into the currently available fossil fuel infrastructure to realize an ideal clean energy system. However, the widespread use of the SOFC technology is hindered by sulfur poisoning at the anode caused by the sulfur impurities in fossil fuels. Therefore, improving the sulfur tolerance of the anode is critical for developing SOFCs for use with fossil fuels. Herein, a novel, highly active, sulfur-tolerant anode for intermediate-temperature SOFCs is prepared via a facile impregnation and limited reaction protocol. During synthesis, Ni nanoparticles, water-storable BaZr 0.4 Ce 0.4 Y 0.2 O 3- δ (BZCY) perovskite, and amorphous BaO are formed in situ and deposited on the surface of a Sm 0.2 Ce 0.8 O 1.9 (SDC) scaffold. More specifically, a porous SDC scaffold is impregnated with a well-designed proton-conducting perovskite oxide liquid precursor with the nominal composition of Ba(Zr 0.4 Ce 0.4 Y 0.2 ) 0.8 Ni 0.2 O 3- δ (BZCYN), calcined and reduced in hydrogen. The as-synthesized hierarchical architecture exhibits high H 2 electro-oxidation activity, excellent operational stability, superior sulfur tolerance, and good thermal cyclability. This work demonstrates the potential of combining nanocatalysts and water-storable materials in advanced electrocatalysts for SOFCs.

  4. Sulfur deactivation of fatty ester hydrogenolysis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Brands, D.S.; U-A-Sai, G.; Poels, E.K.; Bliek, A. [Univ. of Amsterdam (Netherlands). Dept. of Chemical Engineering

    1999-08-15

    Trace organosulfur compounds present as natural impurities in oleochemical feedstocks may lead to activation of copper-containing catalysts applied for hydrogenolysis of esters toward fatty alcohols. In this paper, the sulfur deactivation of Cu/SiO{sub 2} and Cu/ZnO/SiO{sub 2} catalysts was studied in the liquid-phase hydrogenolysis of methyl palmitate. The rate of deactivation is fast and increases as a function of the sulfur-containing compound present: octadecanethiol {approx} dihexadecyl disulfide < benzyl isothiocyanate < methyl p-toluene sulfonate < dihexadecyl sulfide < dibenzothiophene. The rapid deactivation is caused by the fact that sulfur is quantitatively removed from the reaction mixture and because mainly surface sulfides are formed under hydrogenolysis conditions. The life time of a zinc-promoted catalyst is up to two times higher than that of the Cu/SiO{sub 2} catalyst, most likely due to zinc surface sulfide formation. The maximum sulfur coverage obtained after full catalyst deactivation with dibenzothiophene and dihexadecyl sulfide--the sulfur compounds that cause the fastest deactivation--may be as low as 0.07. This is due to the fact that decomposition of these compounds as well as the hydrogenolysis reaction itself proceeds on ensembles of copper atoms. Catalyst regeneration studies reveal that activity cannot be regained by reduction or combined oxidation/reduction treatments. XRD, TPR, and TPO results confirm that no distinct bulk copper or zinc sulfide or sulfate phases are present.

  5. Mechanism of SO2 removal by carbon

    Science.gov (United States)

    Lizzio, Anthony A.; DeBarr, Joseph A.

    1997-01-01

    The reaction of SO2 with carbon (C) in the presence of O2 and H2O involves a series of reactions that leads to the formation of sulfuric acid as the final product. The rate-determining step in the overall process is the oxidation of SO2 to SO3. Three SO2 oxidation reactions are possible. Adsorbed SO2 (C−SO2) can react either with gas phase O2 or with adsorbed oxygen (C−O complex) to form sulfur trioxide (SO3), or gas phase SO2 can react directly with the C−O complex. In optimizing the SO2 removal capabilities of carbon, most studies only assume a given mechanism for SO2 adsorption and conversion to H2SO4 to be operable. The appropriate SO2 oxidation step and role of the C−O complex in this mechanism remain to be determined. The ultimate goal of this study was to prepare activated char from Illinois coal with optimal properties for low-temperature (80−150°C) removal of sulfur dioxide from coal combustion flue gas. The SO2 adsorption capacity of activated char was found to be inversely proportional to the amount of oxygen adsorbed on its surface. A temperature-programmed desorption technique was developed to titrate those sites responsible for adsorption of SO2 and conversion to H2SO4. On the basis of these results, a mechanism for SO2 removal by carbon was proposed. The derived rate expression showed SO2 adsorption to be dependent only on the fundamental rate constant and concentration of carbon atoms designated as free sites. Recent studies indicate a similar relationship exists between the rate of carbon gasification (in CO2 or H2O) and the number of reactive sites as determined by transient kinetics experiments. Utilizing the concept of active or free sites, it was possible to produce a char from Illinois coal having an SO2 adsorption capacity surpassing that of a commercial catalytic activated carbon.

  6. Nitrogen removal from wastewater by a catalytic oxidation method.

    Science.gov (United States)

    Huang, T L; Macinnes, J M; Cliffe, K R

    2001-06-01

    The ammonia-containing waste produced in industries is usually characterized by high concentration and high temperature, and is not treatable by biological methods directly. In this study, a hydrophobic Pt/SDB catalyst was first used in a trickle-bed reactor to remove ammonia from wastewater. In the reactor, both stripping and catalytic oxidation occur simultaneously. It was found that higher temperature and higher oxygen partial pressure enhanced the ammonia removal. A reaction pathway, which involves oxidizing ammonia to nitric oxide, which then further reacts with ammonia to produce nitrogen and water, was confirmed. Small amounts of by-products, nitrites and nitrates were also detected in the resultant reaction solution. These compounds came from the absorption of nitrogen oxides. Both the minimum NO2- selectivity and maximum ammonia removal were achieved when the resultant pH of treated water was near 7.5 for a feed of unbuffered ammonia solution.

  7. Pharmaceutical removal during managed aquifer recharge with pretreatment by advanced oxidation

    KAUST Repository

    Lekkerkerker-Teunissen, Karin

    2012-10-01

    Organic micropollutants (OMPs) are detected in sources for drinking water and treatment possibilities are investigated. Innovative removal technologies are available such as membrane filtration and advanced oxidation, but also biological treatment should be considered. By combining an advanced oxidation process with managed aquifer recharge (MAR), two complementary processes are expected to provide a hybrid system for OMP removal, according to the multiple barrier approach. Laboratory scale batch reactor experiments were conducted to investigate the removal of dissolved organic carbon (DOC) and 14 different pharmaceutically active compounds (PhACs) from MAR influent water and water subjected to oxidation, under different process conditions. A DOC removal of 10% was found in water under oxic (aerobic) conditions for batch reactor experiments, a similar value for DOC removal was observed in the field. Batch reactor experiments for the removal of PhACs showed that the removal of pharmaceuticals ranged from negligible to more than 90%. Under oxic conditions, seven out of 14 pharmaceuticals were removed over 90% and 12 out of 14 pharmaceuticals were removed at more than 50% during 30 days of experiments. Under anoxic conditions, four out of 14 pharmaceuticals were removed over 90% and eight out of 14 pharmaceuticals were removed at more than 50% over 30 days\\' experiments. Carbamazepine and phenazone were persistent both under oxic and anoxic conditions. The PhACs removal efficiency with oxidized water was, for most compounds, comparable to the removal with MAR influent water. Copyright © IWA Publishing 2012.

  8. Pharmaceutical removal during managed aquifer recharge with pretreatment by advanced oxidation

    KAUST Repository

    Lekkerkerker-Teunissen, Karin; Chekol, E. T.; Maeng, Sungkyu; Ghebremichael, Kebreab A.; Houtman, Corine J.; Verliefde, Arne R. D.; Verberk, J. Q J C; Amy, Gary L.; Van Dijk, Johannis C.

    2012-01-01

    Organic micropollutants (OMPs) are detected in sources for drinking water and treatment possibilities are investigated. Innovative removal technologies are available such as membrane filtration and advanced oxidation, but also biological treatment should be considered. By combining an advanced oxidation process with managed aquifer recharge (MAR), two complementary processes are expected to provide a hybrid system for OMP removal, according to the multiple barrier approach. Laboratory scale batch reactor experiments were conducted to investigate the removal of dissolved organic carbon (DOC) and 14 different pharmaceutically active compounds (PhACs) from MAR influent water and water subjected to oxidation, under different process conditions. A DOC removal of 10% was found in water under oxic (aerobic) conditions for batch reactor experiments, a similar value for DOC removal was observed in the field. Batch reactor experiments for the removal of PhACs showed that the removal of pharmaceuticals ranged from negligible to more than 90%. Under oxic conditions, seven out of 14 pharmaceuticals were removed over 90% and 12 out of 14 pharmaceuticals were removed at more than 50% during 30 days of experiments. Under anoxic conditions, four out of 14 pharmaceuticals were removed over 90% and eight out of 14 pharmaceuticals were removed at more than 50% over 30 days' experiments. Carbamazepine and phenazone were persistent both under oxic and anoxic conditions. The PhACs removal efficiency with oxidized water was, for most compounds, comparable to the removal with MAR influent water. Copyright © IWA Publishing 2012.

  9. The application of an isotopic ratio technique to a study of the atmospheric oxidation of sulfur dioxide in the plume from a coal fired power plant

    International Nuclear Information System (INIS)

    Newman, L.; Forrest, J.; Manowitz, B.

    1975-01-01

    The extent of oxidation of sulfur dioxide to sulfate in the plume of a coal fired plant has been studied by using sampling with a single engine aircraft. A technique employing isotopic ratio measurements was utilized in conjunction with simultaneous concentration measurements of sulfur dioxide and sulfate. The use of sulfur hexafluroide as a conservative tracer was explored. The heterogeneous mechanism postulated in an oil fired plume study appears to pertain to the coal fired plume. However, the extent of oxidation seldom exceeded 5% and is limited by the relatively low particulate content of the coal fired plume. Evidence is presented for the apparent dropping out of sulfate from the plume. Implications pertaining to the ambient oxidation of sulfur dioxide are presented. (author)

  10. Demand outlook for sulfur and high-sulfur petroleum coke

    Energy Technology Data Exchange (ETDEWEB)

    Koshkarov, V.Ya.; Danil' yan, P.G.; Feotov, V.E.; Gimaev, R.N.; Koshkarova, M.E.; Sadykova, S.R.; Vodovichenko, N.S.

    1980-01-01

    The feasibility of using sulfur and high-sulfur petroleum coke fines in pyrometallurgical processes and also in the chemical and coal-tar chemical industry is examined. Results of industrial tests on briquetting fines of petroleum coke with a petroleum binder are presented. The feasibility of using the obtained briquets in shaft furnace smelting of oxidized nickel ores, production of anode stock, and also in the chemical industry are demonstrated.

  11. Sulfur-oxidizing bacteria dominate the microbial diversity shift during the pyrite and low-grade pyrolusite bioleaching process.

    Science.gov (United States)

    Han, Yifan; Ma, Xiaomei; Zhao, Wei; Chang, Yunkang; Zhang, Xiaoxia; Wang, Xingbiao; Wang, Jingjing; Huang, Zhiyong

    2013-10-01

    The microbial ecology of the pyrite-pyrolusite bioleaching system and its interaction with ore has not been well-described. A 16S rRNA gene clone library was created to evaluate changes in the microbial community at different stages of the pyrite-pyrolusite bioleaching process in a shaken flask. The results revealed that the bacterial community was disturbed after 5 days of the reaction. Phylogenetic analysis of 16S rRNA sequences demonstrated that the predominant microorganisms were members of a genus of sulfur-oxidizing bacteria, Thiomonas sp., that subsequently remained dominant during the bioleaching process. Compared with iron-oxidizing bacteria, sulfur-oxidizing bacteria were more favorable to the pyrite-pyrolusite bioleaching system. Decreased pH due to microbial acid production was an important condition for bioleaching efficiency. Iron-oxidizing bacteria competed for pyrite reduction power with Mn(IV) in pyrolusite under specific conditions. These results extend our knowledge of microbial dynamics during pyrite-pyrolusite bioleaching, which is a key issue to improve commercial applications. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  12. Wet-cupping removes oxidants and decreases oxidative stress.

    Science.gov (United States)

    Tagil, Suleyman Murat; Celik, Huseyin Tugrul; Ciftci, Sefa; Kazanci, Fatmanur Hacievliyagil; Arslan, Muzeyyen; Erdamar, Nazan; Kesik, Yunus; Erdamar, Husamettin; Dane, Senol

    2014-12-01

    Wet-cupping therapy is one of the oldest known medical techniques. Although it is widely used in various conditions such as acute\\chronic inflammation, infectious diseases, and immune system disorders, its mechanism of action is not fully known. In this study, we investigated the oxidative status as the first step to elucidate possible mechanisms of action of wet cupping. Wet cupping therapy is implemented to 31 healthy volunteers. Venous blood samples and Wet cupping blood samples were taken concurrently. Serum nitricoxide, malondialdehyde levels and activity of superoxide dismutase and myeloperoxidase were measured spectrophotometrically. Wet cupping blood had higher activity of myeloperoxidase, lower activity of superoxide dismutase, higher levels of malondialdehyde and nitricoxide compared to the venous blood. Wet cupping removes oxidants and decreases oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Acidophilic sulfur disproportionation

    Science.gov (United States)

    Hardisty, Dalton S.; Olyphant, Greg A.; Bell, Jonathan B.; Johnson, Adam P.; Pratt, Lisa M.

    2013-07-01

    Bacterial disproportionation of elemental sulfur (S0) is a well-studied metabolism and is not previously reported to occur at pH values less than 4.5. In this study, a sediment core from an abandoned-coal-mine-waste deposit in Southwest Indiana revealed sulfur isotope fractionations between S0 and pyrite (Δ34Ses-py) of up to -35‰, inferred to indicate intense recycling of S0 via bacterial disproportionation and sulfide oxidation. Additionally, the chemistry of seasonally collected pore-water profiles were found to vary, with pore-water pH ranging from 2.2 to 3.8 and observed seasonal redox shifts expressed as abrupt transitions from Fe(III) to Fe(II) dominated conditions, often controlled by fluctuating water table depths. S0 is a common product during the oxidation of pyrite, a process known to generate acidic waters during weathering and production of acid mine drainage. The H2S product of S0 disproportionation, fractionated by up to -8.6‰, is rapidly oxidized to S0 near redox gradients via reaction with Fe(III) allowing for the accumulation of isotopically light S0 that can then become subject to further sulfur disproportionation. A mass-balance model for S0 incorporating pyrite oxidation, S0 disproportionation, and S0 oxidation readily explains the range of observed Δ34Ses-py and emphasizes the necessity of seasonally varying pyrite weathering and metabolic rates, as indicated by the pore water chemistry. The findings of this research suggest that S0 disproportionation is potentially a common microbial process at a pH < 4.5 and can create large sulfur isotope fractionations, even in the absence of sulfate reduction.

  14. Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

    Directory of Open Access Journals (Sweden)

    Natascha Riedinger

    2017-05-01

    Full Text Available The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope—a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory—conditions that result in low organoclastic sulfate reduction rates (SRR. Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT. Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydroxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS. Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron

  15. Permanganate oxidation of sulfur compounds to prevent poisoning of Pd catalysts in water treatment processes.

    Science.gov (United States)

    Angeles-Wedler, Dalia; Mackenzie, Katrin; Kopinke, Frank-Dieter

    2008-08-01

    The practical application of Pd-catalyzed water treatment processes is impeded by catalyst poisoning by reduced sulfur compounds (RSCs). In this study, the potential of permanganate as a selective oxidant for the removal of microbially generated RSCs in water and as a regeneration agent for S-poisoned catalysts was evaluated. Hydrodechlorination using Pd/Al2O3 was carried out as a probe reaction in permanganate-pretreated water. The activity of the Pd catalysts in the successfully pretreated reaction medium was similar to that in deionized water. The catalyst showed no deactivation behavior in the presence of permanganate at a concentration level or = 0.08 mM, a significant but temporary inhibition of the catalytic dechlorination was observed. Unprotected Pd/Al2O3, which had been completely poisoned by sulfide, was reactivated by a combined treatment with permanganate and hydrazine. However, the anthropogenic water pollutants thiophene and carbon disulfide were resistant against permanganate. Together with the preoxidation of catalyst poisons, hydrophobic protection of the catalysts was studied. Pd/zeolite and various hydrophobically coated catalysts showed a higher stability against ionic poisons and permanganate than the uncoated catalyst. By means of a combination of oxidative water pretreatment and hydrophobic catalyst protection, we provide a new tool to harness the potential of Pd-catalyzed hydrodehalogenation for the treatment of real waters.

  16. Study of a combined heterotrophic and sulfur autotrophic denitrification technology for removal of nitrate in water

    International Nuclear Information System (INIS)

    Liu Huijuan; Jiang Wei; Wan Dongjin; Qu Jiuhui

    2009-01-01

    A combined two-step process of heterotrophic denitrification in a fluidized reactor and sulfur autotrophic denitrification processes (CHSAD) was developed for the removal of nitrate in drinking water. In this process, the advantage of high efficiency of heterotrophic denitrification with non-excessive methanol and the advantage of non-pollution of sulfur autotriphic denitrification were integrated in this CHSAD process. And, this CHSAD process had the capacity of pH balance and could control the concentration of SO 4 2- in effluent by adjusting the operation condition. When the influent nitrate was 30 mg NO 3 - -N/L, the reactor could be operated efficiently at the hydraulic retention time (HRT) ranging from 20 to 40 min with C:N ratio (mg CH 3 OH:mg NO 3 - -N) of 2.0 (methanol as carbon source). The nitrate removal was nearly 100% and there was no accumulated nitrite or residual methanol in the effluent. The effluent pH was about 7.5 and the sulfate concentration was lower than 130 mg/L. The maximum volume-loading rate of the reactor was 2.16 kg NO 3 - -N/(m 3 d). The biomass and scanning electron microscopy graphs of biofilm were also analyzed.

  17. The oxidation state of sulfur in apatite: A new oxybarometer?

    Science.gov (United States)

    Fiege, A.; Konecke, B.; Kim, Y.; Simon, A. C.; Becker, U.; Parat, F.

    2016-12-01

    Oxygen fugacity (fO2) of magmatic and hydrothermal systems influences, for instance, crystallization and degassing processes as well as metal solubilities in melts and fluids. Apatite is a ubiquitous mineral in magmatic and hydrothermal environments that can record and preserve volatile zonation. It can contain several thousand μg/g of the redox sensitive element sulfur (S), making S-in-apatite a potential fO2 sensor. Despite the polyvalent properties of S (e.g., S2-, S4+, S6+), the oxidation state and incorporation mechanisms of S in the apatite structure are poorly understood. In this study, the oxidation state of S-in-apatite as a function of fO2 is investigated using X-ray absorption near-edge structures (XANES) spectroscopy at the S K-edge. Apatites crystallized from lamproitic melts at 1000°C, 300 MPa and over a broad range of fO2 and sulfur fugacities (fS2) were measured. Peaks corresponding to S6+ ( 2482 eV), S4+ ( 2478 eV) and S2- ( 2470 eV) were identified in apatite. The integrated S6+/STotal (STotal = S6+ + S4+ + S2-) peak area ratios show a distinct positive correlation with fO2, increasing from 0.17 at FMQ+0 to 0.96 at FMQ+3. Ab-initio calculations were performed to further understand the energetics and geometry of incorporation of S6+, S4+ and S2- into the apatite (F-, Cl-, OH-) end-members. The results confirm that apatite can contain three different oxidations states of S (S6+, S4+, S2-) as a function of fO2. This makes apatite probably the first geologically relevant mineral to incorporate reduced (S2-), intermediate (S4+), and oxidized (S6+) S in variable proportions. We emphasize that the strong dependence of the S oxidation state in apatite as a function of fO2 is also coupled with changing S content of apatite and co-existing melt (i.e., with changing fS2), resulting in a complex correlation between [1] apatite-melt (or fluid) partitioning, [2] redox conditions and [3] the melt and/or fluid composition, making the application of previously

  18. Sulfur passivation and contact methods for GaAs nanowire solar cells

    International Nuclear Information System (INIS)

    Tajik, N; Peng, Z; Kuyanov, P; LaPierre, R R

    2011-01-01

    The effect of sulfur passivation on core-shell p-n junction GaAs nanowire (NW) solar cells has been investigated. Devices of two types were investigated, consisting of indium tin oxide contact dots or opaque Au finger electrodes. Lateral carrier transport from the NWs to the contact fingers was achieved via a p-doped GaAs surface conduction layer. NWs between the opaque contact fingers had sidewall surfaces exposed for passivation by sulfur. The relative cell efficiency increased by 19% upon passivation. The contribution of the thin film grown between the NWs to the total cell efficiency was estimated by removing the NWs using a sonication procedure. Mechanisms of carrier transport and photovoltaic effects are discussed on the basis of spatially resolved laser scanning measurements.

  19. Fractionation of sulfur isotopes in the chemical and biochemical oxidation of sulfide to sulfate

    International Nuclear Information System (INIS)

    Maass, I.; Wetzel, K.; Weise, G.; Heyer, J.

    1983-01-01

    The behaviour of sulfur isotopes in the chemical and biochemical oxidation of marcasite (FeS 2 ) to sulfate has been investigated in rest and shaker cultures at 30 0 C. The microbiological oxidation was carried out using a mixed culture of Thiobacillus. The results show a considerably faster formation of sulfate in the biochemical oxidation in comparison with the chemical oxidation. Isotope analyses of the formed sulfates indicate no or only very small isotope fractionations depending on experimental conditions. The highest enrichment of 32 S in the sulfate is 1.7 per mille. In accordance with the results of other authors it is concluded that in both chemical and biochemical weathering of sedimentary sulfides resulting in the formation of sulfates isotope effects are not of importance. (author)

  20. Contribution of sulfuric acid and oxidized organic compounds to particle formation and growth

    Directory of Open Access Journals (Sweden)

    F. Riccobono

    2012-10-01

    Full Text Available Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to the formation and early growth of nucleated particles. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and α-pinene showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two chemical ionization mass spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene.

    New analysis methods were applied to the data collected with a condensation particle counter battery and a scanning mobility particle sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (Γ, defined as the ratio between the measured growth rate in the presence of α-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed Γ values indicate that the growth is already dominated by organic compounds at particle diameters of 2 nm. Both the absolute growth rates and Γ showed a strong dependence on particle size, supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particle growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. Finally, the size resolved growth analysis indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

  1. Simultaneous heterotrophic and sulfur-oxidizing autotrophic denitrification process for drinking water treatment: control of sulfate production.

    Science.gov (United States)

    Sahinkaya, Erkan; Dursun, Nesrin; Kilic, Adem; Demirel, Sevgi; Uyanik, Sinan; Cinar, Ozer

    2011-12-15

    A long-term performance of a packed-bed bioreactor containing sulfur and limestone was evaluated for the denitrification of drinking water. Autotrophic denitrification rate was limited by the slow dissolution rate of sulfur and limestone. Dissolution of limestone for alkalinity supplementation increased hardness due to release of Ca(2+). Sulfate production is the main disadvantage of the sulfur autotrophic denitrification process. The effluent sulfate concentration was reduced to values below drinking water guidelines by stimulating the simultaneous heterotrophic and autotrophic denitrification with methanol supplementation. Complete removal of 75 mg/L NO(3)-N with effluent sulfate concentration of around 225 mg/L was achieved when methanol was supplemented at methanol/NO(3)-N ratio of 1.67 (mg/mg), which was much lower than the theoretical value of 2.47 for heterotrophic denitrification. Batch studies showed that sulfur-based autotrophic NO(2)-N reduction rate was around three times lower than the reduction rate of NO(3)-N, which led to NO(2)-N accumulation at high loadings. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Bioleaching of metals from soils or sediments using the microbial sulfur cycle

    NARCIS (Netherlands)

    Tichy, R.

    1998-01-01

    Reduced inorganic sulfur species like elemental sulfur or sulfide are sensitive to changes in oxidative environments. Generally, inorganic reduced sulfur exists in natural environments in a solid phase, whereas its oxidation leads to sulfur solubilization and a production of acidity. This

  3. Desulfurization of Diesel Fuel by Oxidation and Solvent Extraction

    OpenAIRE

    Wadood Taher Mohammed; Raghad Fareed Kassim Almilly; Sheam Bahjat Abdulkareem Al-Ali

    2015-01-01

    This research presents a study in ultra-desulfurization of diesel fuel produced from conventional hydro desulfurization process, using oxidation and solvent extraction techniques. Dibenzothiophene (DBT) was the organosulfur compound that had been detected in sulfur removal. The oxidation process used hydrogen peroxide as an oxidant and acetic acid as homogeneous catalyst . The solvent extraction process used acetonitrile (ACN) and N-methyl – 2 - pyrrolidone (NMP) as extractants . Also the ef...

  4. Kinetics of aerobic oxidation of volatile sulfur compounds in wastewater and biofilm from sewers

    DEFF Research Database (Denmark)

    Rudelle, Elise Alice; Vollertsen, Jes; Hvitved-Jacobsen, Thorkild

    2013-01-01

    Laboratory experiments were conducted to investigate the kinetics of aerobic chemical and biological oxidation of selected odorous volatile sulfur compounds (VSCs) by wastewater and biofilm from sewers. The VSCs included methyl mercaptan (MeSH), ethyl mercaptan (EtSH), dimethyl sulfide (DMS......-spot downstream of a force main and the other was a gravity sewer transporting young aerobic wastewater. The kinetics of VSC oxidation for both wastewater and suspended biofilm samples followed a first-order rate equation. The average values of the reaction rate constants demonstrated the following order...... in the aerobic wastewater....

  5. Environmental aspects of the combustion of sulfur-bearing fuels

    International Nuclear Information System (INIS)

    Manowitz, B.; Lipfert, F.W.

    1990-01-01

    This paper describes the origins of sulfur in fossil fuels and the consequences of its release into the environment after combustion, with emphasis on the United States. Typical sulfur contents of fuels are given, together with fuel uses and the resulting air concentrations of sulfur air pollutants. Atmospheric transformation and pollutant removal processes are described, as they affect the pathways of sulfur through the environment. The environmental effects discussed include impacts on human health, degradation of materials, acidification of ecosystems, and effects on vegetation and atmospheric visibility. The paper concludes with a recommendation for the use of risk assessment to assess the need for regulations which may require the removal of sulfur from fuels or their combustion products

  6. Sulfur isotope studies of biogenic sulfur emissions at Wallops Island, Virginia

    International Nuclear Information System (INIS)

    Hitchcock, D.R.; Black, M.S.; Herbst, R.P.

    1978-03-01

    This research attempted to determine whether it is possible to measure the stable sulfur isotope distributions of atmospheric particulate and gaseous sulphur, and to use this information together with measurements of the ambient levels of sulfur gases and particulate sulfate and sodium in testing certain hypotheses. Sulfur dioxide and particulate sulfur samples were collected at a coastal marine location and their delta (34)S values were determined. These data were used together with sodium concentrations to determine the presence of biogenic sulfur and the identity of the biological processes producing it. Excess (non-seasalt) sulfate levels ranged from 2 to 26 micrograms/cu m and SO2 from 1 to 9 ppb. Analyses of air mass origins and lead concentrations indicated that some anthropogenic contaminants were present on all days, but the isotope data revealed that most of the atmospheric sulfur originated locally from the metabolism of bacterial sulfate reducers on all days, and that the atmospheric reactions leading to the production of sulfate from this biogenic sulfur source are extremely rapid. Delta 34 S values of atmospheric sulfur dioxide correlated well with those of excess sulfate, and implied little or no sulfur isotope fractionation during the oxidation of sulfur gases to sulfate

  7. Method of burning sulfur-containing fuels in a fluidized bed boiler

    Science.gov (United States)

    Jones, Brian C.

    1982-01-01

    A method of burning a sulfur-containing fuel in a fluidized bed of sulfur oxide sorbent wherein the overall utilization of sulfur oxide sorbent is increased by comminuting the bed drain solids to a smaller average particle size, preferably on the order of 50 microns, and reinjecting the comminuted bed drain solids into the bed. In comminuting the bed drain solids, particles of spent sulfur sorbent contained therein are fractured thereby exposing unreacted sorbent surface. Upon reinjecting the comminuted bed drain solids into the bed, the newly-exposed unreacted sorbent surface is available for sulfur oxide sorption, thereby increasing overall sorbent utilization.

  8. Influence of zinc oxide during different stages of sulfur vulcanization. Elucidated by model compound studies

    NARCIS (Netherlands)

    Heideman, G.; Datta, Rabin; Noordermeer, Jacobus W.M.; van Baarle, B.

    2005-01-01

    The addition of zinc oxide (ZnO) as an activator for the sulfur vulcanization of rubbers enhances the vulcanization efficiency and vulcanizate properties and reduces the vulcanization time. The first part of this article deals with the reduction and optimization of the amount of ZnO. Two different

  9. Practical considerations of pyrite oxidation control in uranium tailings

    International Nuclear Information System (INIS)

    1984-05-01

    The problems posed by the oxidation of pyrite in uranium tailings include the generation of sulfuric acid and acid sulfate metal salts. These have substantial negative impacts on watercourse biota by themselves, and the lowered pH levels tend to mobilize heavy metals present in the tailings the rate of oxidation of pyrite at lower pH levels is catalyzed by sulfur and iron oxidizing bacteria present in soils. No single clear solution to the problems came from this study. Exclusion of air is a most important preventative of bacterial catalysis of oxidation. Bactericides, chemically breaking the chain of integrated oxidation reactions, maintaining anaerobic conditions, or maintaining a neutral or alkaline pH all reduce the oxidation rate. Removal of pyrite by flotation will reduce but not eliminate the impact of pyrite oxidation. Controlled oxidation of the remaining sulfide in the flotation tails would provide an innocuous tailing so far as acidity generation is concerned

  10. Heavy metal extraction from PCB wastewater treatment sludge by sulfuric acid

    International Nuclear Information System (INIS)

    Kuan, Yu-Chung; Lee, I-Hsien; Chern, Jia-Ming

    2010-01-01

    Heavy metals contaminated wastewater sludge is classified as hazardous solid waste and needs to be properly treated to prevent releasing heavy metals to the environment. In this study, the wastewater treatment sludge from a printed circuit board manufacturing plant was treated in a batch reactor by sulfuric acid to remove the contained heavy metals. The effects of sulfuric acid concentration and solid to liquid ratio on the heavy metal removal efficiencies were investigated. The experimental results showed that the total and individual heavy metal removal efficiencies increased with increasing sulfuric acid concentration, but decreased with increasing solid to liquid ratio. A mathematical model was developed to predict the residual sludge weights at varying sulfuric concentrations and solid to liquid ratios. The trivalent heavy metal ions, iron and chromium were more difficult to be removed than the divalent ions, copper, zinc, nickel, and cadmium. For 5 g/L solid to liquid ratio, more than 99.9% of heavy metals can be removed from the sludge by treating with 0.5 M sulfuric acid in 2 h.

  11. Relationship between corrosion and the biological sulfur cycle: A review

    Energy Technology Data Exchange (ETDEWEB)

    Little, B.J.; Ray, R.I.; Pope, R.K.

    2000-04-01

    Sulfur and sulfur compounds can produce pitting, crevice corrosion, dealloying, stress corrosion cracking, and stress-oriented hydrogen-induced cracking of susceptible metals and alloys. Even though the metabolic by-products of the biological sulfur cycle are extremely corrosive, there are no correlations between numbers and types of sulfur-related organisms and the probability or rate of corrosion, Determination of specific mechanisms for corrosion caused by microbiologically mediated oxidation and reduction of sulfur and sulfur compounds is complicated by the variety of potential metabolic-energy sources and by-products; the coexistence of reduced and oxidized sulfur species; competing reactions with inorganic and organic compounds; and the versatility and adaptability of microorganisms in biofilms. The microbial ecology of sulfur-rich environments is poorly understood because of the association of aerobes and anaerobes and the mutualism or succession of heterotrophs to autotrophs. The physical scale over which the sulfur cycle influences corrosion varies with the environment. The complete sulfur cycle of oxidation and reduction reactions can take place in macroenvironments, including sewers and polluted harbors, or within the microenvironment of biofilms. In this review, reactions of sulfur and sulfur compounds resulting in corrosion were discussed in the context of environmental processes important to corrosion.

  12. SYNTHESIS OF SULFUR-BASED WATER TREATMENT AGENT FROM SULFUR DIOXIDE WASTE STREAMS

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Maohong Fan; Adrienne Cooper

    2004-11-01

    Absorption of sulfur dioxide from a simulated flue gas was investigated for the production of polymeric ferric sulfate (PFS), a highly effective coagulant useful in treatment of drinking water and wastewater. The reaction for PFS synthesis took place near atmospheric pressure and at temperatures of 30-80 C. SO{sub 2} removal efficiencies greater than 90% were achieved, with ferrous iron concentrations in the product less than 0.1%. A factorial analysis of the effect of temperature, oxidant dosage, SO{sub 2} concentration, and gas flow rate on SO{sub 2} removal efficiency was carried out, and statistical analyses are conducted. The solid PFS was also characterized with different methods. Characterization results have shown that PFS possesses both crystalline and non-crystalline structure. The kinetics of reactions among FeSO{sub 4} {center_dot} 7H{sub 2}O, NaHSO{sub 3} and NaClO{sub 3} was investigated. Characterizations of dry PFS synthesized from SO{sub 2} show the PFS possesses amorphous structure, which is desired for it to be a good coagulant in water and wastewater treatment. A series of lab-scale experiments were conducted to evaluate the performance of PFS synthesized from waste sulfur dioxide, ferrous sulfate and sodium chlorate. The performance assessments were based on the comparison of PFS and other conventional and new coagulants for the removal of turbidity and arsenic under different laboratory coagulant conditions. Pilot plant studies were conducted at Des Moines Water Works in Iowa and at the City of Savannah Industrial and Domestic (I&D) Water Treatment Plant in Port Wentworth, Georgia. PFS performances were compared with those of conventional coagulants. The tests in both water treatment plants have shown that PFS is, in general, comparable or better than other coagulants in removal of turbidity and organic substances. The corrosion behavior of polymeric ferric sulfate (PFS) prepared from SO{sub 2} and ferric chloride (FC) were compared. Results

  13. Removal of hazardous gaseous pollutants from industrial flue gases by a novel multi-stage fluidized bed desulfurizer.

    Science.gov (United States)

    Mohanty, C R; Adapala, Sivaji; Meikap, B C

    2009-06-15

    Sulfur dioxide and other sulfur compounds are generated as primary pollutants from the major industries such as sulfuric acid plants, cupper smelters, catalytic cracking units, etc. and cause acid rain. To remove the SO(2) from waste flue gas a three-stage counter-current multi-stage fluidized bed adsorber was developed as desulfurization equipment and operated in continuous bubbling fluidization regime for the two-phase system. This paper represents the desulfurization of gas mixtures by chemical sorption of sulfur dioxide on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of the multi-stage fluidized bed reactor are of high mass transfer and high gas-solid residence time that can enhance the removal of acid gas at low temperature by dry method. Experiments were carried out in the bubbling fluidization regime supported by visual observation. The effects of the operating parameters such as sorbent (lime) flow rate, superficial gas velocity, and the weir height on SO(2) removal efficiency in the multistage fluidized bed are reported. The results have indicated that the removal efficiency of the sulfur dioxide was found to be 65% at high solid flow rate (2.0 kg/h) corresponding to lower gas velocity (0.265 m/s), wier height of 70 mm and SO(2) concentration of 500 ppm at room temperature.

  14. Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria (First External Review Draft, Sep 2007)

    Science.gov (United States)

    EPA has announced that the First External Review Draft of the Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria has been made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evaluatio...

  15. Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

    Science.gov (United States)

    Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

    2018-03-01

    Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Heavy metal removal from water/wastewater by nanosized metal oxides: A review

    International Nuclear Information System (INIS)

    Hua, Ming; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

    2012-01-01

    Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs’ preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance.

  17. Study on the Relation between the Mn/Al Mixed Oxides Composition and Performance of FCC Sulfur Transfer Agent

    Directory of Open Access Journals (Sweden)

    Ruiyu Jiang

    2016-01-01

    Full Text Available A sulfur transfer agent in catalysts can effectively reduce the emission of SO2 with minimum adverse effects on the catalytic cracking ability of the primary catalyst. In this paper, the composition and performance of sulfur transfer agents with different oxidative active components (such as Cu, Fe, Ni, Co, Ba, Zn and Cr were prepared by acid peptization technique and characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and N2 adsorption-desorption technique. The relationship between the composition and performance of the new sulfur transfer agents was investigated and the regeneration and recycling of the agents were performed. The results indicates that copper is a very good desulfurization active component. Moreover, the presence of CO has no significant effect on the absorption ability of SO2 by the sulfur transfer agent.

  18. Hexavalent chromium reduction in a sulfur reducing packed-bed bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Sahinkaya, Erkan, E-mail: erkansahinkaya@yahoo.com [Department of Bioengineering, Istanbul Medeniyet University, Goeztepe, Istanbul (Turkey); Kilic, Adem [Department of Environmental Engineering, Harran University, Osmanbey Campus, 63000 Sanliurfa (Turkey); Altun, Muslum [Department of Chemistry, Hacettepe University, Beytepe, Ankara (Turkey); Komnitsas, Kostas [Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania (Greece); Lens, Piet N.L. [Unesco-IHE Institute for Water Education, Westvest 7, Delft 2611 AX (Netherlands)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Elemental sulfur can be used as electron acceptor for sulfide production. Black-Right-Pointing-Pointer Biogenically produced sulfide reduces Cr(VI) to the much less toxic and immobile form of Cr(III). Black-Right-Pointing-Pointer Sulfur packed bioreactor is efficient for Cr(VI) containing wastewater treatment. Black-Right-Pointing-Pointer Reduced form of chromium precipitates in the bioreactor. - Abstract: The most commonly used approach for the detoxification of hazardous industrial effluents and wastewaters containing Cr(VI) is its reduction to the much less toxic and immobile form of Cr(III). This study investigates the cleanup of Cr(VI) containing wastewaters using elemental sulfur as electron acceptor, for the production of hydrogen sulfide that induces Cr(VI) reduction. An elemental sulfur reducing packed-bed bioreactor was operated at 28-30 Degree-Sign C for more than 250 days under varying influent Cr(VI) concentrations (5.0-50.0 mg/L) and hydraulic retention times (HRTs, 0.36-1.0 day). Ethanol or acetate (1000 mg/L COD) was used as carbon source and electron donor. The degree of COD oxidation varied between 30% and 85%, depending on the operating conditions and the type of organic carbon source. The oxidation of organic matter was coupled with the production of hydrogen sulfide, which reached a maximum concentration of 750 mg/L. The biologically produced hydrogen sulfide reduced Cr(VI) chemically to Cr(III) that precipitated in the reactor. Reduction of Cr(VI) and removal efficiency of total chromium always exceeded 97% and 85%, respectively, implying that the reduced chromium was retained in the bioreactor. This study showed that sulfur can be used as an electron acceptor to produce hydrogen sulfide that induces efficient reduction and immobilization of Cr(VI), thus enabling decontamination of Cr(VI) polluted wastewaters.

  19. Effect of selective removal of organic matter and iron oxides on the ...

    African Journals Online (AJOL)

    The effect of selective removal of organic matter and amorphous and crystalline iron oxides on N2-BET specific surface areas of some soil clays was evaluated. Clay fractions from 10 kaolinitic tropical soils were successively treated to remove organic matter by oxidation with Na hypochlorite, amorphous Fe oxide with acid ...

  20. Surface structure-dependent pyrite oxidation in relatively dry and moist air: Implications for the reaction mechanism and sulfur evolution

    Science.gov (United States)

    Zhu, Jianxi; Xian, Haiyang; Lin, Xiaoju; Tang, Hongmei; Du, Runxiang; Yang, Yiping; Zhu, Runliang; Liang, Xiaoliang; Wei, Jingming; Teng, H. Henry; He, Hongping

    2018-05-01

    Pyrite oxidation not only is environmentally significant in the formation of acid mine (or acid rock) drainage and oxidative acidification of lacustrine sediment but also is a critical stage in geochemical sulfur evolution. The oxidation process is always controlled by the reactivity of pyrite, which in turn is controlled by its surface structure. In this study, the oxidation behavior of naturally existing {1 0 0}, {1 1 1}, and {2 1 0} facets of pyrite was investigated using a comprehensive approach combining X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, and time-of-flight secondary-ion mass spectrometry with periodic density functional theoretical (DFT) calculations. The experimental results show that (i) the initial oxidation rates of both pyrite {1 1 1} and {2 1 0} are much greater than that of pyrite {1 0 0}; (ii) the initial oxidation rate of pyrite {2 1 0} is greater than that of pyrite {1 1 1} in low relative humidity, which is reversed in high relative humidity; and (iii) inner sphere oxygen-bearing sulfur species are originally generated from surface reactions and then converted to outer sphere species. The facet dependent rate law can be expressed as: r{hkl} =k{hkl}haP0.5(t + 1) - 0.5 , where r{hkl} is the orientation dependent reaction rate, k{hkl} is the orientation dependent rate constant, h is the relative humidity, P is the oxygen partial pressure, and t is the oxidation time in seconds. {1 1 1} is the most sensitive facet for pyrite oxidation. Combined with DFT theoretical investigations, water catalyzed electron transfer is speculated as the rate-limiting step. These findings disclose the structure-reactivity dependence of pyrite, which not only presents new insight into the mechanism of pyrite oxidation but also provides fundamental data to evaluate sulfur speciation evolution, suggesting that the surface structure sensitivity should be considered to estimate the reactivity at the mineral

  1. Surface-initiated growth of thin oxide coatings for Li-sulfur battery cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyu Tae; Black, Robert; Yim, Taeeun; Ji, Xiulei; Nazar, Linda F. [University of Waterloo, Department of Chemistry, Waterloo, ON (Canada)

    2012-12-15

    The concept of surface-initiated growth of oxides on functionalized carbons is introduced as a method to inhibit the dissolution of polysulfide ions in Li-S battery cathode materials. MO{sub x} (M: Si, V) thin layers are homogeneously coated on nanostructured carbon-sulfur composites. The coating significantly inhibits the dissolution of polysulfides on cycling, resulting in enhanced cycle performance and coulombic efficiency of the Li-S battery. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Building better lithium-sulfur batteries: from LiNO3 to solid oxide catalyst

    Science.gov (United States)

    Ding, Ning; Zhou, Lan; Zhou, Changwei; Geng, Dongsheng; Yang, Jin; Chien, Sheau Wei; Liu, Zhaolin; Ng, Man-Fai; Yu, Aishui; Hor, T. S. Andy; Sullivan, Michael B.; Zong, Yun

    2016-09-01

    Lithium nitrate (LiNO3) is known as an important electrolyte additive in lithium-sulfur (Li-S) batteries. The prevailing understanding is that LiNO3 reacts with metallic lithium anode to form a passivation layer which suppresses redox shuttles of lithium polysulfides, enabling good rechargeability of Li-S batteries. However, this view is seeing more challenges in the recent studies, and above all, the inability of inhibiting polysulfide reduction on Li anode. A closely related issue is the progressive reduction of LiNO3 on Li anode which elevates internal resistance of the cell and compromises its cycling stability. Herein, we systematically investigated the function of LiNO3 in redox-shuttle suppression, and propose the suppression as a result of catalyzed oxidation of polysulfides to sulfur by nitrate anions on or in the proximity of the electrode surface upon cell charging. This hypothesis is supported by both density functional theory calculations and the nitrate anions-suppressed self-discharge rate in Li-S cells. The catalytic mechanism is further validated by the use of ruthenium oxide (RuO2, a good oxygen evolution catalyst) on cathode, which equips the LiNO3-free cell with higher capacity and improved capacity retention over 400 cycles.

  3. Oxidation state of sulfur, iron and tin at the surface of float glasses

    International Nuclear Information System (INIS)

    Lagarde, P; Flank, A-M; Jupille, J; Montigaud, H

    2009-01-01

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO 3 ), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 μm 2 ) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  4. Oxidation state of sulfur, iron and tin at the surface of float glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lagarde, P; Flank, A-M [Synchrotron SOLEIL, l' Orme des Merisiers, BP 48 91192 Gif/Yvette cedex (France); Jupille, J [IMPMC, Universite P. and M. Curie, Campus de Boucicaut, 140 rue de Lourmel 75015 Paris (France); Montigaud, H [Saint-Gobain Recherche 39, quai Lucien Lefranc, BP 135 93303 Aubervilliers Cedex (France)

    2009-11-15

    Sulfur is an important element of glasses, not because of its amount, always very low (less than 0.4 % in weight of SO{sub 3}), but because of its role since it actively participates to the refinement process and, combined to other elements, it can be responsible for the coloration of the glass. Iron is also of a major importance in most of the glasses. In the case of the float glass, the two faces, because of the fabrication process, are different in terms of composition (presence of Sn for one face) and also in terms of oxidation state of these minority elements (Fe, Sn, S). There should be a subtle interplay between the concentrations and the oxidation states of these different minority elements, and anyway these variations occur over a thickness of the order of few micrometers below the surface. Using the high intensity and the focusing properties (3 x 3 {mu}m{sup 2}) of the x-ray beam from the Lucia beamline, we have therefore studied the speciation of iron and sulfur near the face of a float glass in relation with the behavior of tin. This has been obtained by combining elemental x-ray fluorescence cartography and x-ray micro-absorption at the different K-edges.

  5. Keep your Sox on: Community genomics-directed isolation and microscopic characterization of the dominant subsurface sulfur-oxidizing bacterium in a sediment aquifer

    Science.gov (United States)

    Mullin, S. W.; Wrighton, K. C.; Luef, B.; Wilkins, M. J.; Handley, K. M.; Williams, K. H.; Banfield, J. F.

    2012-12-01

    Community genomics and proteomics (proteogenomics) can be used to predict the metabolic potential of complex microbial communities and provide insight into microbial activity and nutrient cycling in situ. Inferences regarding the physiology of specific organisms then can guide isolation efforts, which, if successful, can yield strains that can be metabolically and structurally characterized to further test metagenomic predictions. Here we used proteogenomic data from an acetate-stimulated, sulfidic sediment column deployed in a groundwater well in Rifle, CO to direct laboratory amendment experiments to isolate a bacterial strain potentially involved in sulfur oxidation for physiological and microscopic characterization (Handley et al, submitted 2012). Field strains of Sulfurovum (genome r9c2) were predicted to be capable of CO2 fixation via the reverse TCA cycle and sulfur oxidation (Sox and SQR) coupled to either nitrate reduction (Nap, Nir, Nos) in anaerobic environments or oxygen reduction in microaerobic (cbb3 and bd oxidases) environments; however, key genes for sulfur oxidation (soxXAB) were not identified. Sulfidic groundwater and sediment from the Rifle site were used to inoculate cultures that contained various sulfur species, with and without nitrate and oxygen. We isolated a bacterium, Sulfurovum sp. OBA, whose 16S rRNA gene shares 99.8 % identity to the gene of the dominant genomically characterized strain (genome r9c2) in the Rifle sediment column. The 16S rRNA gene of the isolate most closely matches (95 % sequence identity) the gene of Sulfurovum sp. NBC37-1, a genome-sequenced deep-sea sulfur oxidizer. Strain OBA grew via polysulfide, colloidal sulfur, and tetrathionate oxidation coupled to nitrate reduction under autotrophic and mixotrophic conditions. Strain OBA also grew heterotrophically, oxidizing glucose, fructose, mannose, and maltose with nitrate as an electron acceptor. Over the range of oxygen concentrations tested, strain OBA was not

  6. Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition

    International Nuclear Information System (INIS)

    Chen Chuan; Ren Nanqi; Wang Aijie; Liu Lihong; Lee, Duu-Jong

    2010-01-01

    The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed.

  7. Zeolites as catalyzer to environmental control. Nitric oxide removal

    International Nuclear Information System (INIS)

    Montes, C.; Zapata N, M; Villa H, A.L.

    1995-01-01

    Zeolites and the microporous materials related to them are a class of environmental catalysts, it which are used to remove the produced gases in combustion process (as mobile sources). In this work the importance that has catalysis for environment improvement is emphasized. A review of recent progress in the use of certain zeolitic material as catalysts for nitric oxide elimination of combustion systems is presented. More used nitric oxide removal methods are presented, as well as its advantages and disadvantages. Furthermore, it is emphasized on the need of accomplishing more investigation projects on the development of an active catalyst for the decomposition of the nitric oxide in its elements (N and O)

  8. Deep desulfurization of diesel oil oxidized by Fe (VI) systems

    Energy Technology Data Exchange (ETDEWEB)

    Shuzhi Liu; Baohui Wang; Baochen Cui; Lanlan Sun [Daqing Petroleum Institute, Daqing (China). College of Chemistry and Chemical Engineering

    2008-03-15

    Fe (VI) compound, such as K{sub 2}FeO{sub 4}, is a powerful oxidizing agent. Its oxidative potential is higher than KMnO{sub 4}, O{sub 3} and Cl{sub 2}. Oxidation activity of Fe (VI) compounds can be adjusted by modifying their structure and pH value of media. The reduction of Fe (VI), differing from Cr and Mn, results in a relatively non-toxic by-product Fe (III) compounds, which suggests that Fe (VI) compound is an environmentally friendly oxidant. Oxidation of model sulfur compound and diesel oil by K{sub 2}FeO{sub 4} in water-phase, in organic acid and in the presence of phase-transfer catalysts is investigated, respectively. The results show that the activity of oxidation of benzothiophene (BT) and dibenzothiophene (DBT) is low in water-phase, even adding phase-transfer catalyst to the system, because K{sub 2}FeO{sub 4} reacts rapidly with water to form brown Fe(OH){sub 3} to lose ability of oxidation of organic sulfur compounds. The activity of oxidation of the BT and DBT increases markedly in acetic acid. Moreover, the addition of the solid catalyst to the acetic acid medium promotes very remarkably oxidation of organic sulfur compounds. Conversions of the DBT and BT are 98.4% and 70.1%, respectively, under the condition of room temperature, atmospheric pressure, acetic acid/oil (v/v) = 1.0, K{sub 2}FeO{sub 4}/S (mol/mol) = 1.0 and catalyst/K{sub 2}FeO{sub 4} (mol/mol) = 1.0. Under the same condition, diesel oil is oxidized, followed by furfural extraction, the results display sulfur removal rate is 96.7% and sulfur content in diesel oil reduces from 457 ppm to 15.1 ppm. 11 refs., 9 figs., 5 tabs.

  9. Tetrathionate and Elemental Sulfur Shape the Isotope Composition of Sulfate in Acid Mine Drainage

    Directory of Open Access Journals (Sweden)

    Nurgul Balci

    2017-08-01

    Full Text Available Sulfur compounds in intermediate valence states, for example elemental sulfur, thiosulfate, and tetrathionate, are important players in the biogeochemical sulfur cycle. However, key understanding about the pathways of oxidation involving mixed-valance state sulfur species is still missing. Here we report the sulfur and oxygen isotope fractionation effects during the oxidation of tetrathionate (S4O62− and elemental sulfur (S° to sulfate in bacterial cultures in acidic conditions. Oxidation of tetrathionate by Acidithiobacillus thiooxidans produced thiosulfate, elemental sulfur and sulfate. Up to 34% of the tetrathionate consumed by the bacteria could not be accounted for in sulfate or other intermediate-valence state sulfur species over the experiments. The oxidation of tetrathionate yielded sulfate that was initially enriched in 34S (ε34SSO4−S4O6 by +7.9‰, followed by a decrease to +1.4‰ over the experiment duration, with an average ε34SSO4−S4O6 of +3.5 ± 0.2‰ after a month of incubation. We attribute this significant sulfur isotope fractionation to enzymatic disproportionation reactions occurring during tetrathionate decomposition, and to the incomplete transformation of tetrathionate into sulfate. The oxygen isotope composition of sulfate (δ18OSO4 from the tetrathionate oxidation experiments indicate that 62% of the oxygen in the formed sulfate was derived from water. The remaining 38% of the oxygen was either inherited from the supplied tetrathionate, or supplied from dissolved atmospheric oxygen (O2. During the oxidation of elemental sulfur, the product sulfate became depleted in 34S between −1.8 and 0‰ relative to the elemental sulfur with an average for ε34SSO4−S0 of −0.9 ± 0.2‰ and all the oxygen atoms in the sulfate derived from water with an average normal oxygen isotope fractionation (ε18OSO4−H2O of −4.4‰. The differences observed in δ18OSO4 and the sulfur isotope composition of sulfate (δ34SSO4

  10. Flue gas cleanup using the Moving-Bed Copper Oxide Process

    Energy Technology Data Exchange (ETDEWEB)

    Pennline, Henry W; Hoffman, James S

    2013-10-01

    The use of copper oxide on a support had been envisioned as a gas cleanup technique to remove sulfur dioxide (SO{sub 2}) and nitric oxides (NO{sub x}) from flue gas produced by the combustion of coal for electric power generation. In general, dry, regenerable flue gas cleanup techniques that use a sorbent can have various advantages, such as simultaneous removal of pollutants, production of a salable by-product, and low costs when compared to commercially available wet scrubbing technology. Due to the temperature of reaction, the placement of the process into an advanced power system could actually increase the thermal efficiency of the plant. The Moving-Bed Copper Oxide Process is capable of simultaneously removing sulfur oxides and nitric oxides within the reactor system. In this regenerable sorbent technique, the use of the copper oxide sorbent was originally in a fluidized bed, but the more recent effort developed the use of the sorbent in a moving-bed reactor design. A pilot facility or life-cycle test system was constructed so that an integrated testing of the sorbent over absorption/regeneration cycles could be conducted. A parametric study of the total process was then performed where all process steps, including absorption and regeneration, were continuously operated and experimentally evaluated. The parametric effects, including absorption temperature, sorbent and gas residence times, inlet SO{sub 2} and NO{sub x} concentration, and flyash loadings, on removal efficiencies and overall operational performance were determined. Although some of the research results have not been previously published because of previous collaborative restrictions, a summary of these past findings is presented in this communication. Additionally, the potential use of the process for criteria pollutant removal in oxy-firing of fossil fuel for carbon sequestration purposes is discussed.

  11. Mixing-assisted oxidative desulfurization of model sulfur compounds using polyoxometalate/H2O2 catalytic system

    Directory of Open Access Journals (Sweden)

    Angelo Earvin Sy Choi

    2016-07-01

    Full Text Available Desulfurization of fossil fuel derived oil is needed in order to comply with environmental regulations. Dibenzothiophene and benzothiophene are among the predominant sulfur compound present in raw diesel oil. In this study, mixing-assisted oxidative desulfurization of dibenzothiophene and benzothiophene were carried out using polyoxometalate/H2O2 systems and a phase transfer agent. The effects of reaction time (2–30 min and temperature (30–70 °C were examined in the oxidation of model sulfur compounds mixed in toluene. A pseudo first-order reaction kinetic model and the Arrhenius equation were utilized in order to evaluate the kinetic rate constant and activation energy of each catalyst tested in the desulfurization process. Results showed the order of catalytic activity and activation energy of the different polyoxometalate catalysts to be H3PW12O40 > H3PM12O40 > H4SiW12O40 for both dibenzothiophene and benzothiophene.

  12. Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

    Science.gov (United States)

    Liu, Chao; Li, Bin; Du, Haishun; Lv, Dong; Zhang, Yuedong; Yu, Guang; Mu, Xindong; Peng, Hui

    2016-10-20

    In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Sulfidogenic biotreatment of synthetic acid mine drainage and sulfide oxidation in anaerobic baffled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bekmezci, Ozan K.; Ucar, Deniz [Harran University, Environmental Engineering Department, Osmanbey Campus, 63000 Sanliurfa (Turkey); Kaksonen, Anna H. [CSIRO Land and Water, Underwood Avenue, Floreat, WA 6014 (Australia); Sahinkaya, Erkan, E-mail: erkansahinkaya@yahoo.com [Harran University, Environmental Engineering Department, Osmanbey Campus, 63000 Sanliurfa (Turkey)

    2011-05-30

    The treatment of synthetic acid mine drainage (AMD) water (pH 3.0-6.5) containing sulfate (3.0-3.5 g L{sup -1}) and various metals (Co, Cu, Fe, Mn, Ni, and Zn) was studied in an ethanol-fed sulfate-reducing 4-compartment anaerobic baffled reactor (ABR) at 32 {sup o}C. The reactor was operated for 160 days at different chemical oxygen demand (COD)/sulfate ratios, hydraulic retention times (HRT), pH, and metal concentrations to study the robustness of the process. The last compartment of the reactor was aerated at different rates to study the bio-oxidation of sulfide to elemental sulfur. The highest sulfate reduction efficiency (88%) was obtained with a feed sulfate concentration of 3.5 g L{sup -1}, COD/sulfate mass ratio of 0.737, feed pH of 3.0 and HRT of 2 days without aeration in the 4th compartment. The corresponding COD removal efficiency was about 92%. The alkalinity produced in the sulfidogenic ethanol oxidation neutralized the acidic mine water from pH 3.0-4.5 to pH 7.0-8.0. Effluent soluble and total heavy metal concentrations were substantially reduced with removal efficiencies generally higher than 99%, except for Mn (25-77%). Limited aeration in the 4th compartment of ABR promoted incomplete oxidation of sulfide to elemental sulfur rather than complete oxidation to sulfate. Depending on the aeration rate and HRT, 32-74% of produced sulfide was oxidized to elemental sulfur. This study demonstrates that by optimizing operating conditions, sulfate reduction, metal removal, alkalinity generation, and excess sulfide oxidation can be achieved in a single ABR treating AMD.

  14. TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER

    Directory of Open Access Journals (Sweden)

    RAISA NASTAS

    2012-03-01

    Full Text Available Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O, or metals (Fe, Cu, Ni, on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions.

  15. Bioleaching of heavy metal polluted sediment: kinetics of leaching and microbial sulfur oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Loeser, C. [Technische Universitaet Dresden, Institut fuer Lebenmitteltechnik und Bioverfahrenstechnik, D-01062 Dresden (Germany); Zehnsdorf, A. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Umwelt- und Biotechnologisches Zentrum (UBZ), Permoserstrasse 15, D-04318 Leipzig (Germany); Goersch, K.; Seidel, H. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Department Bioremediation, Permoserstrasse 15, D-04318 Leipzig (Germany)

    2005-12-01

    Remediation of heavy metal polluted sediment through bioleaching using elemental sulfur (S{sup 0}) as the leaching agent can be regarded as a two-step process: firstly, the microbial oxidation of the added S{sup 0} to sulfuric acid and, secondly, the reaction of the produced acid with the sediment. Here, both subprocesses were studied in detail independently: oxidized river sediment was either suspended in sulfuric acid of various strengths, or mixed with various amounts of finely ground S{sup 0} powder (diameter of the S{sup 0} particles between 1 and 175 {mu}m with a Rosin-Rammler-Sperling-Bennet (RRSB) distribution and an average diameter of 35 {mu}m) and suspended in water. The leaching process was observed by repeated analysis of the suspension concerning pH, soluble sulfate and metals, and remaining S{sup 0}. In the case of abiotic leaching with H{sub 2}SO{sub 4}, the reaction between the acid and the sediment resulted in a gradual increase in pH and a solubilization of sediment-borne heavy metals which required some time; 80 % of the finally solubilized heavy metals was dissolved after 1 h, 90 % after 10 h, and 100 % after 100 h. In the case of bioleaching, the rate of S{sup 0} oxidation was maximal at the beginning, gradually diminished with time, and was proportional to the initial amount of S{sup 0}. Due to its very low solubility in water, S{sup 0} is oxidized in a surface reaction catalyzed by attached bacteria. The oxidation let the particles shrink, their surface became smaller and, thus, the S{sup 0} oxidation rate gradually decreased. The shrinking rate was time-invariant and, at 30 C, amounted to 0.5 {mu}m/day (or 100 {mu}g/cm{sup 2}/day). Within 21 days, 90 % of the applied S{sup 0} was oxidized. Three models with a different degree of complexity have been developed that describe this S{sup 0} oxidation, assuming S{sup 0} particles of uniform size (I), using a measured particle size distribution (II), or applying an adapted RRSB distribution (III

  16. Thermochemical Study on the Sulfurization of Fission Products in Spent Nuclear Fuel

    International Nuclear Information System (INIS)

    Lee, Jung Won; Yang, M. S.; Park, G. I.; Kim, W. K.; Lee, J. W.

    2005-11-01

    The thermodynamic behavior of the sulfurization of Nd, and Eu element, which are contained in spent nuclear fuel as fission products was investigated through collection and properties analysis of thermodynamic data in sulfurization of uranium oxides, thermodynamic properties analysis for the oxidation and reduction of fission products, and test and analysis for sulfurization characteristics of Nd and Eu oxide. And also, analysis on thermodynamic data, such as M-O-S phase stability diagram and changes of Gibbs free energy for sulfurization of uranium and Nd 2 O 3 and Eu 2 O 3 were carried out. Nd 2 O 3 and Eu 2 O 3 are sulfurized into Nd 2 O 2 S and Eu 2 O 2 S or NdySx and EuySx at a range of 400 to 450 .deg. C, while uranium oxides, such as UO 2 and U 3 O 8 remain unreacted up to 450 .deg. C Formation of UOS at 500 .deg. C is initiated by sulfurization of uranium oxides. Hence, reaction temperature for the sulfurization of the Nd 2 O 3 and Eu 2 O 3 was selected as a 450 .deg. C

  17. Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors: Impact of sulfur passivation on gate stack quality

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Dian; Wang, Wei; Gong, Xiao, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Material Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Tok, Eng-Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2016-01-14

    The effect of room temperature sulfur passivation of the surface of Ge{sub 0.83}Sn{sub 0.17} prior to high-k dielectric (HfO{sub 2}) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the chemical bonding at the interface of HfO{sub 2} and Ge{sub 0.83}Sn{sub 0.17}. Sulfur passivation is found to be effective in suppressing the formation of both Ge oxides and Sn oxides. A comparison of XPS results for sulfur-passivated and non-passivated Ge{sub 0.83}Sn{sub 0.17} samples shows that sulfur passivation of the GeSn surface could also suppress the surface segregation of Sn atoms. In addition, sulfur passivation reduces the interface trap density D{sub it} at the high-k dielectric/Ge{sub 0.83}Sn{sub 0.17} interface from the valence band edge to the midgap of Ge{sub 0.83}Sn{sub 0.17}, as compared with a non-passivated control. The impact of the improved D{sub it} is demonstrated in Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs with sulfur passivation show improved subthreshold swing S, intrinsic transconductance G{sub m,int}, and effective hole mobility μ{sub eff} as compared with the non-passivated control. At a high inversion carrier density N{sub inv} of 1 × 10{sup 13 }cm{sup −2}, sulfur passivation increases μ{sub eff} by 25% in Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs.

  18. Biosorption and biodegradation of a sulfur dye in high-strength dyeing wastewater by Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Nguyen, Thai Anh; Fu, Chun-Chieh; Juang, Ruey-Shin

    2016-11-01

    The ability of the bacterial strain Acidithiobacillus thiooxidans to remove sulfur blue 15 (SB15) dye from water samples was examined. This bacterium could not only oxidize sulfur compounds to sulfuric acid but also promote the attachment of the cells to the surface of sulfidic particles, therefore serving as an efficient biosorbent. The biosorption isotherms were better described by the Langmuir equation than by the Freundlich or Dubinin-Radushkevich equation. Also, the biosorption process followed the pseudo-second-order kinetics. At pH 8.3 and SB15 concentrations up to 2000 mg L(-1) in the biomass/mineral salt solution, the dye removal and decolorization were 87.5% and 91.4%, respectively, following the biosorption process. Biodegradation was proposed as a subsequent process for the remaining dye (250-350 mg L(-1)). A central composite design was used to analyze independent variables in the response surface methodology study. Under the optimal conditions (i.e., initial dye concentration of 300 mg L(-1), initial biomass concentration of 1.0 g L(-1), initial pH of 11.7, and yeast extract dose of 60 mg L(-1)), up to 50% of SB15 was removed after 4 days of biodegradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Sulfur transformation during rapid hydropyrolysis of coal under high pressure by using a continuous free fall pyrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    W.-C. Xu; M. Kumagai

    2003-02-01

    The behavior of sulfur transformation during rapid hydropyrolysis of coal was investigated using a pressurized, continuous free fall pyrolyzer under the conditions of temperature ranging from 923 to 1123 K and hydrogen pressure up to 5 MPa. The yields of sulfur converted to gas, tar and char were determined, together with the analyses of sulfur form distributions in coals and chars. The results showed that the decomposition of inorganic sulfur species was affected only by the temperature, while the increases in temperature and hydrogen pressure obviously enhanced the removal of organic sulfur from coal. The extent of organic sulfur removal was proportional to the coal conversion, depending on coal type. A significant retention of gaseous sulfur products by the organic matrix of the char was observed during hydropyrolysis of a Chinese coal above 1023 K, even under the pressurized hydrogen atmosphere. The kinetic analysis indicates that the rate of organic sulfur removal from coal was 0.2th-order with respect to the hydrogen pressure, and the activation energy for total sulfur removal and organic sulfur removal is 17 26 and 13 55 kJ/mol, respectively. The low activation energies suggest that the transformation and removal of sulfur from coal might be controlled by the diffusion and/or thermodynamic equilibrium during hydropyrolysis under the pressurized conditions. 29 refs., 10 figs., 3 tabs.

  20. Mixing-assisted oxidative desulfurization of model sulfur compounds using polyoxometalate/H2O2 catalytic system

    OpenAIRE

    Angelo Earvin Sy Choi; Susan Roces; Nathaniel Dugos; Meng-Wei Wan

    2016-01-01

    Desulfurization of fossil fuel derived oil is needed in order to comply with environmental regulations. Dibenzothiophene and benzothiophene are among the predominant sulfur compound present in raw diesel oil. In this study, mixing-assisted oxidative desulfurization of dibenzothiophene and benzothiophene were carried out using polyoxometalate/H2O2 systems and a phase transfer agent. The effects of reaction time (2–30 min) and temperature (30–70 °C) were examined in the oxidation of model sulfu...

  1. Transformation of sulfur during pyrolysis and hydropyrolysis of coal

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Li, B.; Yang, J.; Zhang, B. [Chinese Academy of Sciences, Taiyuan (China). Inst. of Coal Chemistry

    1998-05-01

    It is reported that the transformation of sulfur during pyrolysis (Py) under nitrogen and hydropyrolysis (HyPy) of Chinese Yanzhou high sulfur bituminous coal and Hongmiao lignite was studied in a fixed-bed reactor. The volatile sulfur-containing products were determined by gas chromatography with flame photometric detection. The sulfur in initial coal and char (mainly aliphatic and thiophenic sulfur forms) was quantitatively analyzed using X-ray photoelectron spectroscopy (XPS). The desulfurization yield was calculated by elemental analysis. The main volatile sulfur-containing gas was H{sub 2}S in both Py and HyPy. Both the elemental analysis and XPS results indicated that more sulfur was removed in HyPy than in Py under nitrogen. Thiophenic sulfur can be partially hydrogenated and removed in HyPy. Pyrite can be reduced to a ferrous sulfide completely even as low as 400{degree}C in HyPy while in Py the reduction reaction continues up to 650{degree}C. Mineral matter can not only fix H{sub 2}S produced in Py and HyPy to form higher sulfur content chars but also catalyses the desulfurization reactions to form lower sulfur content tars in HyPy. 24 refs., 8 figs., 4 tabs.

  2. Partial oxidation process for producing a stream of hot purified gas

    Science.gov (United States)

    Leininger, T.F.; Robin, A.M.; Wolfenbarger, J.K.; Suggitt, R.M.

    1995-03-28

    A partial oxidation process is described for the production of a stream of hot clean gas substantially free from particulate matter, ammonia, alkali metal compounds, halides and sulfur-containing gas for use as synthesis gas, reducing gas, or fuel gas. A hydrocarbonaceous fuel comprising a solid carbonaceous fuel with or without liquid hydrocarbonaceous fuel or gaseous hydrocarbon fuel, wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H{sub 2}, CO, CO{sub 2}, H{sub 2}O, CH{sub 4}, NH{sub 3}, HCl, HF, H{sub 2}S, COS, N{sub 2}, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is split into two streams which are separately deslagged, cleaned and recombined. Ammonia in the gas mixture is catalytically disproportionated into N{sub 2} and H{sub 2}. The ammonia-free gas stream is then cooled and halides in the gas stream are reacted with a supplementary alkali metal compound to remove HCl and HF. Alkali metal halides, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000 F. 1 figure.

  3. Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification

    Energy Technology Data Exchange (ETDEWEB)

    Simões, Eliana F.C. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal); Leitão, João M.M., E-mail: jleitao@ff.uc.pt [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Esteves da Silva, Joaquim C.G. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal)

    2017-04-01

    Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM{sup −1} and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. - Highlights: • S,N co-doped CDs were microwave synthetized from citric acid, urea and sodium thiosulfate. • The NO fluorescence sensing was evaluated at pH 7. • The selective and sensitive detection of NO at pH 7 was achieved. • Good NO quantification results in serum samples were obtained.

  4. Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification

    International Nuclear Information System (INIS)

    Simões, Eliana F.C.; Leitão, João M.M.; Esteves da Silva, Joaquim C.G.

    2017-01-01

    Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM"−"1 and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. - Highlights: • S,N co-doped CDs were microwave synthetized from citric acid, urea and sodium thiosulfate. • The NO fluorescence sensing was evaluated at pH 7. • The selective and sensitive detection of NO at pH 7 was achieved. • Good NO quantification results in serum samples were obtained.

  5. In liquid laser treated graphene oxide for dye removal

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Paola, E-mail: rsspla1@gmail.com [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy); Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., West Waterloo, Ontario N2L 3G1 (Canada); D’Urso, Luisa [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy); Hu, Anming [Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 57996-2210 (United States); Zhou, Norman [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., West Waterloo, Ontario N2L 3G1 (Canada); Compagnini, Giuseppe [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy)

    2015-09-01

    Highlights: • Graphene oxide and reduced graphene oxide were tested as adsorbents for dye removal from water. • Reduced graphene oxide was obtained after laser irradiation of a colloidal suspension of graphene oxide. • Methylene blue was chosen as the dye to test graphene oxide and reduced graphene oxide. - Abstract: The presence of dyes, pharmaceuticals and many other pollutants in wastewaters is critical due to severe effects on the human beings and on the environment. Here, solutions of graphene oxide (GO) and reduced graphene oxide (rGO) were tested as adsorbents for the removal of methylene blue (MB), a cationic dye, from aqueous media. The reduced forms of graphene oxide were obtained after laser irradiation of colloidal suspensions of graphene oxide, obtained by the Hummers and Offeman's method. We observed that both graphene oxide and its reduced forms are excellent adsorbents towards methylene blue. In particular, rGO showed a higher adsorption capacity than GO, suggesting that a strict control of laser irradiation time permits to obtain rGO with different degrees of reduction and therefore the residual oxygenated functional groups may influence the adsorption behaviour more or less. Characterization of the samples by atomic force microscopy (AFM) showed that produced rGO sheets via laser irradiation exhibited a discontinuous surface where some holes could be detected contributing to an enhancement of the rGO surface area that is a higher adsorption capacity.

  6. Evaluation of biological hydrogen sulfide oxidation coupled with two-stage upflow filtration for groundwater treatment.

    Science.gov (United States)

    Levine, Audrey D; Raymer, Blake J; Jahn, Johna

    2004-01-01

    Hydrogen sulfide in groundwater can be oxidized by aerobic bacteria to form elemental sulfur and biomass. While this treatment approach is effective for conversion of hydrogen sulfide, it is important to have adequate control of the biomass exiting the biological treatment system to prevent release of elemental sulfur into the distribution system. Pilot scale tests were conducted on a Florida groundwater to evaluate the use of two-stage upflow filtration downstream of biological sulfur oxidation. The combined biological and filtration process was capable of excellent removal of hydrogen sulfide and associated turbidity. Additional benefits of this treatment approach include elimination of odor generation, reduction of chlorine demand, and improved stability of the finished water.

  7. BIOTRANSFORMATION AND REMOVAL OF SULFUR FROM DIBENZOTHIOPHENE USING IMPROVED BIOCATALYTIC METHODS

    OpenAIRE

    LAROTTA, C. E; MORA, A. L; MADERO, A; MOGOLLÓN, L. I

    1998-01-01

    Three methods for the removal of sulfurfrom dibenzothiophene were evaluated using biocatalytic processes. The methods were a microbial, an enzymatic and a combined one that involves a previous enzymatic oxidation followed by microbial degradation. The byconversion was evaluated over the molecular dibenzothiophene model, obtaining higher byconversion percentages through the combined method. The microorganisms used in this study correspond to several Colombian indigenous strains isolated by dir...

  8. Garlic Sulfur Compounds Suppress Cancerogenesis and Oxidative Stress: a Review

    Directory of Open Access Journals (Sweden)

    Dvořáková M.

    2015-06-01

    Full Text Available Garlic has long been considered a food with many health benefits. Several studies have confirmed that sulfur compounds are responsible for the positive effects of garlic on organisms. Garlic acts as an antioxidant by increasing antioxidant enzyme activity, reducing reactive oxygen species generation, and protecting proteins and lipids from oxidation. Garlic suppresses carcinogenesis through several mechanisms: (1 it reduces oxidative stress, and therefore, prevents damage to DNA; (2 it induces apoptosis or cell cycle arrest in cancer cells; and (3 it modifies gene expression through histon acetylation. The positive effects of garlic could be mediated by several mechanisms. It influences signalling pathways of gasotransmitters such as hydrogen sulfide. Garlic enhances hydrogen sulfide production both through its direct release and through an increase in activity of enzymes which produce hydrogen sulfide. Hydrogen sulfide acts as a signalling molecule in various tissues and participates in the regulation of many physiological processes. We can presume that garlic, which is able to release hydrogen sulfide, exhibits effects similar to those of this gasotransmitter.

  9. Prevention of formation of acid drainage from high-sulfur coal refuse by inhibition of iron- and sulfur-oxidizing microorganisms. II. Inhibition in run of mine refuse under simulated field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, P.R.

    1987-01-01

    The combination of sodium lauryl sulfate and benzoic acid effectively inhibits iron- and sulfur-oxidizing bacteria in coal refuse and prevents the conversion of iron pyrite to sulfate, ferric iron, and sulfuric acid, thereby significantly reducing the formation of acidic drainage from coal refuse. The inhibitors were effective in a concentration of 1.1. mg/kg refuse, and data indicate that the SLS was in excess of the concentration required. The treatment was compatible with the use of lime for neutralization of acid present prior to inhibition of its formation.

  10. Effect of Prussian blue on organic sulfur of coal in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A. [Selcuk University, Konya (Turkey). Dept. of Chemical Engineering

    2007-01-15

    This study is an attempt to desulfurize organic sulfur from coal samples with ferric hexacyanoferrate (II), Fe{sub 4} (Fe(CN){sub 6}), as the desulfurization agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the level of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K. The organic sulfur removal rate sharply increases from 10 min to 30 min stirring time. After 30 min, it reaches a value of plateau. Particle size between -100 mesh and -200 mesh slightly affects the amount of organic sulfur removal. Gradual increase in the concentration of ferric hexacyanoferrate (II) raised the magnitude of desulfurization, but at higher concentration, the variation is not significant.

  11. 34S/32S fractionation in sulfur cycles catalyzed by anaerobic bacteria

    Science.gov (United States)

    Fry, B.; Gest, H.; Hayes, J. M.

    1988-01-01

    Stable isotopic distributions in the sulfur cycle were studied with pure and mixed cultures of the anaerobic bacteria, Chlorobium vibrioforme and Desulfovibrio vulgaris. D. vulgaris and C. vibrioforme can catalyze three reactions constituting a complete anaerobic sulfur cycle: reduction of sulfate to sulfide (D. vulgaris), oxidation of sulfide to elemental sulfur (C. vibrioforme), and oxidation of sulfur to sulfate (C. vibrioforme). In all experiments, the first and last reactions favored concentration of the light 32S isotope in products (isotopic fractionation factor epsilon = -7.2 and -1.7%, respectively), whereas oxidation of sulfide favored concentration of the heavy 34S isotope in products (epsilon = +1.7%). Experimental results and model calculations suggest that elemental sulfur enriched in 34S versus sulfide may be a biogeochemical marker for the presence of sulfide-oxidizing bacteria in modern and ancient environments.

  12. Irradiation technologies used for combustion gases and diluted sulfurous gases decontamination

    International Nuclear Information System (INIS)

    Villanueva Z, Loreto

    1998-01-01

    A brief description of irradiation technology used for ambient decontamination is presented here. The system is adequate fort gas and liquid effluents and solid wastes. In particular, the characteristics and applications of the irradiation done with an electron beam to gas effluent is described, mainly to clean combustion gases and other industrial gases containing sulfur and nitrogen oxides, S O x and N O x , respectively. This technology permits the remove of these contaminants and the acquisition of a solid byproduct, an ammonia sulfate-nitrate, apt for fertilizer applications. (author)

  13. 78 FR 27387 - Notice of Workshop and Call for Information on Integrated Science Assessment for Oxides of Sulfur

    Science.gov (United States)

    2013-05-10

    ... periodically, and, if appropriate, to revise existing air quality criteria to reflect advances in scientific... such as chemistry and physics, sources and emissions, analytical methodology, transport and... will update the scientific assessment presented in the Integrated Science Assessment for Sulfur Oxides...

  14. Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition.

    Science.gov (United States)

    Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

    2010-07-15

    The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed. 2010 Elsevier B.V. All rights reserved.

  15. The partitioning of sulfur between multicomponent aqueous fluids and felsic melts

    Science.gov (United States)

    Binder, Bernd; Wenzel, Thomas; Keppler, Hans

    2018-02-01

    Sulfur partitioning between melt and fluid phase largely controls the environmental impact of volcanic eruptions. Fluid/melt partitioning data also provide the physical basis for interpreting changes in volcanic gas compositions that are used in eruption forecasts. To better constrain some variables that control the behavior of sulfur in felsic systems, in particular the interaction between different volatiles, we studied the partitioning of sulfur between aqueous fluids and haplogranitic melts at 200 MPa and 750-850 °C as a function of oxygen fugacity (Ni-NiO or Re-ReO2 buffer), melt composition (Al/(Na + K) ratio), and fluid composition (NaCl and CO2 content). The data confirm a first-order influence of oxygen fugacity on the partitioning of sulfur. Under "reducing conditions" (Ni-NiO buffer), D fluid/melt is nearly one order of magnitude larger (323 ± 14 for a metaluminous melt) than under "oxidizing conditions" (Re-ReO2 buffer; 74 ± 5 for a metaluminous melt). This effect is likely related to a major change in sulfur speciation in both melt and fluid. Raman spectra of the quenched fluids show the presence of H2S and HS- under reducing conditions and of SO4 2- and HSO4 - under oxidizing conditions, while SO2 is undetectable. The latter observation suggests that already at the Re-ReO2 buffer, sulfur in the fluid is almost completely in the S6+ state and, therefore, more oxidized than expected according to current models. CO2 in the fluid (up to x CO2 = 0.3) has no effect on the fluid/melt partitioning of sulfur, neither under oxidizing nor under reducing conditions. However, the effect of NaCl depends on redox state. While at oxidizing conditions, D fluid/melt is independent of x NaCl, the fluid/melt partition coefficient strongly decreases with NaCl content under reducing conditions, probably due to a change from H2S to NaSH as dominant sulfur species in the fluid. A decrease of D fluid/melt with alkali content in the melt is observed over the entire

  16. VOC removal and deodorization of effluent gases from an industrial plant by photo-oxidation, chemical oxidation, and ozonization.

    Science.gov (United States)

    Domeño, Celia; Rodríguez-Lafuente, Angel; Martos, J M; Bilbao, Rafael; Nerín, Cristina

    2010-04-01

    The efficiency of photo-oxidation, chemical oxidation by sodium hypochlorite, and ozonization for the industrial-scale removal of volatile organic compounds (VOCs) and odors from gaseous emissions was studied by applying these treatments (in an experimental system) to substances passing through an emission stack of a factory producing maize derivatives. Absorption and ozonization were the most efficient treatment, removing 75% and 98% of VOCs, respectively, while photo-oxidation only removed about 59%. The emitted chemical compounds and odors were identified and quantified by gas chromatography-mass spectrometry (in full-scan mode). In addition to presenting the results, their implications for selecting optimal processes for treating volatile emissions are discussed.

  17. Biodesulfurization of refractory organic sulfur compounds in fossil fuels.

    Science.gov (United States)

    Soleimani, Mehran; Bassi, Amarjeet; Margaritis, Argyrios

    2007-01-01

    The stringent new regulations to lower sulfur content in fossil fuels require new economic and efficient methods for desulfurization of recalcitrant organic sulfur. Hydrodesulfurization of such compounds is very costly and requires high operating temperature and pressure. Biodesulfurization is a non-invasive approach that can specifically remove sulfur from refractory hydrocarbons under mild conditions and it can be potentially used in industrial desulfurization. Intensive research has been conducted in microbiology and molecular biology of the competent strains to increase their desulfurization activity; however, even the highest activity obtained is still insufficient to fulfill the industrial requirements. To improve the biodesulfurization efficiency, more work is needed in areas such as increasing specific desulfurization activity, hydrocarbon phase tolerance, sulfur removal at higher temperature, and isolating new strains for desulfurizing a broader range of sulfur compounds. This article comprehensively reviews and discusses key issues, advances and challenges for a competitive biodesulfurization process.

  18. Method of distillation of sulfurous bituminous shales

    Energy Technology Data Exchange (ETDEWEB)

    Hallback, A J.S.; Bergh, S V

    1918-04-22

    A method of distillation of sulfur-containing bituminous shales is characterized by passing the hot sulfur-containing and oil-containing gases and vapors formed during the distillation through burned shale containing iron oxide, so that when these gases and vapors are thereafter cooled they will be, as far as possible, free from sulfur compounds. The patent contains six more claims.

  19. Simultaneous removal of SO{sub 2} and NOx by microwave with potassium permanganate over zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Zai-shan Wei; He-jingying Niu; Yong-feng Ji [Sun Yat-sen University, Guangzhou (China). School of Environmental Science and Engineering

    2009-02-15

    Simultaneous sulfur dioxide (SO{sub 2}) and nitrogen oxides (NOx) removal from flue gas can be achieved with high efficiency by microwave with potassium permanganate (KMnO{sub 4}) over zeolite. The experimental results showed that the microwave reactor could be used to oxidation of SO{sub 2} to sulfate with the best desulfurization efficiency of 96.8% and oxidize NOx to nitrates with the best NOx removal efficiency of 98.4%. Microwave accentuates catalytic oxidation treatment, and microwave addition can increase the SO{sub 2} and NOx removal efficiency by 7.2% and 12.2% separately. The addition of zeolite to microwave potassium permanganate increases from 16.5% to 43.5% the microwave removal efficiency for SO{sub 2}, and the NOx removal efficiency from 85.6% to 98.2%. The additional use of potassium permanganate to the microwave zeolite leads to the enhancement of SO{sub 2} removal efficiency up from 53.9% to 95%, and denitrification efficiency up from 85.6% to 98.2%. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and denitrification are 259 W and 0.357 s, respectively. SO{sub 2} and NOx were rapidly oxidized in microwave induced catalytic oxidation reaction using potassium permanganate with zeolite being the catalyst and microwave absorbent. 13 refs., 6 figs.

  20. Cu-based metal–organic framework/activated carbon composites for sulfur compounds removal

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Rui-Hua [State Key Laboratory of Coal Science and Technology, Co-founded by Shanxi Province and the Ministry of Science and Technology, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, West Yingze Street Number 79, Taiyuan 030024 (China); Zhang, Zhen-Rong [Institute of Applied Chemical, Shanxi (China); Fan, Hui-Ling, E-mail: fanhuiling@tyut.edu.cn [State Key Laboratory of Coal Science and Technology, Co-founded by Shanxi Province and the Ministry of Science and Technology, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, West Yingze Street Number 79, Taiyuan 030024 (China); Zhen, Tian [Deparment of Analysis and Service Center Micromertics instrumental Ltd, Shanghai (China); Shangguan, Ju; Mi, Jie [State Key Laboratory of Coal Science and Technology, Co-founded by Shanxi Province and the Ministry of Science and Technology, Institute for Chemical Engineering of Coal, Taiyuan University of Technology, West Yingze Street Number 79, Taiyuan 030024 (China)

    2017-02-01

    Highlights: • Incorporation of AC less than 2% in MOF-199 can increase micropores and BET surface area, as evidenced by N{sub 2} adsorption. • Lewis acid (unsaturated copper) sites could also be increased in the modified MOF-199, as revealed by Py-IR characterization. • Composite with 2% AC showed highest sulfur capacity with 8.46 and 8.53% for H{sub 2}S and CH{sub 3}SCH{sub 3}, respectively. • The adsorption of CH{sub 3}SCH{sub 3} on composite is reversible, physic-adsorption and weak chemisorption were involved. - Abstract: MOF-199 was modified by incorporating activated carbon (AC) during its synthesis under hydrothermal conditions to improve its performance in the removal of hydrogen sulfide (H{sub 2}S) and dimethyl sulfide (CH{sub 3}SCH{sub 3}). A variety of different characterization techniques including X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM), pyridine adsorption infrared spectroscopy (Py-IR), thermogravimetric- mass spectroscopy (TG-MS) and X-ray photoelectron spectroscopy (XPS) were used to analyze the fresh and exhausted composites. It was found that the composites, which have an amount of AC of less than 2%, had the same morphology as those of pristine MOF-199, but exhibited a more ordered crystallinity structure as well as higher surface area. The composite with 2% AC incorporation showed highest sulfur capacity of 8.46 and 8.53% for H{sub 2}S and CH{sub 3}SCH{sub 3}, respectively, which increased by 51 and 41% compared to that of MOF-199. This improvement was attributed to the formation of more micropores and especially the increased number of unsaturated copper metal sites, as revealed by Py-IR. It is suggested the chemical reaction was apparent during adsorption of H{sub 2}S, which resulted in the formation of CuS and the collapse of the MOF structure. Whereas reversible chemisorption was found for CH{sub 3}SCH{sub 3} adsorption, as

  1. Partial oxidation of jet fuels over Rh/Al_2O_3. Design and reaction kinetics of sulfur-containing surrogates

    International Nuclear Information System (INIS)

    Baer, Julian Nicolaas

    2016-01-01

    The conversion of logistic fuels via catalytic partial oxidation (CPOX) on Rh/Al_2O_3 at short contact times is an efficient method for generating hydrogen-rich synthesis gas. Depending on the inlet conditions, fuel, and catalyst, high syngas yields, low by-product formation, and rates of high fuel conversion can be achieved. CPOX is relevant for mobile hydrogen generation, e.g., on board of airplanes in order to increase the fuel efficiency via fuel cell-based auxiliary power units. Jet fuels contain hundreds of different hydrocarbons and a significant amount of sulfur. The hydrocarbon composition and sulfur content of a jet fuel vary depending on distributor, origin, and refinement of the crude oil. Little is known about the influence of the various compounds on the synthesis-gas yield and the impact of sulfur on the product yield. In this work, the influence of three main chemical compounds of a jet fuel (aromatics, alkanes, and sulfur compounds) on syngas selectivity, the catalyst deactivation process, and reaction sequence is unraveled. As representative components of alkanes and aromatics, n-dodecane and 1,2,4-trimethylbenzene were chosen for ex-situ and in-situ investigations on the CPOX over Rh/Al_2O_3, respectively. Additionally, for a fixed paraffin-to-aromatics ratio, benzothiophene or dibenzothiophene were added as a sulfur component in three different concentrations. The knowledge gained about the catalytic partial oxidation of jet fuels and their surrogates is used to identify requirements for jet fuels in mobile applications based on CPOX and to optimize the overall system efficiency. The results show an influence of the surrogate composition on syngas selectivity. The tendency for syngas formation increases with higher paraffin contents. A growing tendency for by-product formation can be observed with increasing aromatics contents in the fuel. The impact of sulfur on the reaction system shows an immediate change in the product distribution. An

  2. Performance evaluation of the sulfur-redox-reaction-activated up-flow anaerobic sludge blanket and down-flow hanging sponge anaerobic/anoxic sequencing batch reactor system for municipal sewage treatment.

    Science.gov (United States)

    Hatamoto, Masashi; Ohtsuki, Kota; Maharjan, Namita; Ono, Shinya; Dehama, Kazuya; Sakamoto, Kenichi; Takahashi, Masanobu; Yamaguchi, Takashi

    2016-03-01

    A sulfur-redox-reaction-activated up-flow anaerobic sludge blanket (UASB) and down-flow hanging sponge (DHS) system, combined with an anaerobic/anoxic sequencing batch reactor (A2SBR), has been used for municipal sewage treatment for over 2 years. The present system achieved a removal rate of 95±14% for BOD, 74±22% for total nitrogen, and 78±25% for total phosphorus, including low water temperature conditions. Sludge conversion rates during the operational period were 0.016 and 0.218 g-VSS g-COD-removed(-1) for the UASB, and DHS, respectively, which are similar to a conventional UASB-DHS system, which is not used of sulfur-redox-reaction, for sewage treatment. Using the sulfur-redox reaction made advanced treatment of municipal wastewater with minimal sludge generation possible, even in winter. Furthermore, the occurrence of a unique phenomenon, known as the anaerobic sulfur oxidation reaction, was confirmed in the UASB reactor under the winter season. Copyright © 2016. Published by Elsevier Ltd.

  3. Selective catalytic reduction of sulfur dioxide to elemental sulfur. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1995-06-01

    This project has investigated new metal oxide catalysts for the single stage selective reduction of SO{sub 2} to elemental sulfur by a reductant, such as CO. Significant progress in catalyst development has been made during the course of the project. We have found that fluorite oxides, CeO{sub 2} and ZrO{sub 2}, and rare earth zirconates such as Gd{sub 2}Zr{sub 2}O{sub 7} are active and stable catalysts for reduction Of SO{sub 2} by CO. More than 95% sulfur yield was achieved at reaction temperatures about 450{degrees}C or higher with the feed gas of stoichiometric composition. Reaction of SO{sub 2} and CO over these catalysts demonstrated a strong correlation of catalytic activity with the catalyst oxygen mobility. Furthermore, the catalytic activity and resistance to H{sub 2}O and CO{sub 2} poisoning of these catalysts were significantly enhanced by adding small amounts of transition metals, such as Co, Ni, Co, etc. The resulting transition metal-fluorite oxide composite catalyst has superior activity and stability, and shows promise in long use for the development of a greatly simplified single-step sulfur recovery process to treat variable and dilute SO{sub 2} concentration gas streams. Among various active composite catalyst systems the Cu-CeO{sub 2} system has been extensively studied. XRD, XPS, and STEM analyses of the used Cu-CeO{sub 2} catalyst found that the fluorite crystal structure of ceria was stable at the present reaction conditions, small amounts of copper was dispersed and stabilized on the ceria matrix, and excess copper oxide particles formed copper sulfide crystals of little contribution to catalytic activity. A working catalyst consisted of partially sulfated cerium oxide surface and partially sulfided copper clusters. The overall reaction kinetics were approximately represented by a first order equation.

  4. Removal of arsenic from groundwater by using a native isolated arsenite-oxidizing bacterium.

    Science.gov (United States)

    Kao, An-Chieh; Chu, Yu-Ju; Hsu, Fu-Lan; Liao, Vivian Hsiu-Chuan

    2013-12-01

    Arsenic (As) contamination of groundwater is a significant public health concern. In this study, the removal of arsenic from groundwater using biological processes was investigated. The efficiency of arsenite (As(III)) bacterial oxidation and subsequent arsenate (As(V)) removal from contaminated groundwater using bacterial biomass was examined. A novel As(III)-oxidizing bacterium (As7325) was isolated from the aquifer in the blackfoot disease (BFD) endemic area in Taiwan. As7325 oxidized 2300μg/l As(III) using in situ As(III)-contaminated groundwater under aerobic conditions within 1d. After the oxidation of As(III) to As(V), As(V) removal was further examined using As7325 cell pellets. The results showed that As(V) could be adsorbed efficiently by lyophilized As7325 cell pellets, the efficiency of which was related to lyophilized cell pellet concentration. Our study conducted the examination of an alternative technology for the removal of As(III) and As(V) from groundwater, indicating that the oxidation of As(III)-contaminated groundwater by native isolated bacterium, followed by As(V) removal using bacterial biomass is a potentially effective technology for the treatment of As(III)-contaminated groundwater. © 2013.

  5. Genomic features of "Candidatus Venteria ishoeyi", a new sulfur-oxidizing macrobacterium from the Humboldt Sulfuretum off Chile.

    Directory of Open Access Journals (Sweden)

    Alexis Fonseca

    Full Text Available The Humboldt Sulfuretum (HS, in the productive Humboldt Eastern Boundary Current Upwelling Ecosystem, extends under the hypoxic waters of the Peru-Chile Undercurrent (ca. 6°S and ca. 36°S. Studies show that primeval sulfuretums held diverse prokaryotic life, and, while rare today, still sustain species-rich giant sulfur-oxidizing bacterial communities. We here present the genomic features of a new bacteria of the HS, "Candidatus Venteria ishoeyi" ("Ca. V. ishoeyi" in the family Thiotrichaceae.Three identical filaments were micro-manipulated from reduced sediments collected off central Chile; their DNA was extracted, amplified, and sequenced by a Roche 454 GS FLX platform. Using three sequenced libraries and through de novo genome assembly, a draft genome of 5.7 Mbp, 495 scaffolds, and a N50 of 70 kbp, was obtained. The 16S rRNA gene phylogenetic analysis showed that "Ca. V. ishoeyi" is related to non-vacuolate forms presently known as Beggiatoa or Beggiatoa-like forms. The complete set of genes involved in respiratory nitrate-reduction to dinitrogen was identified in "Ca. V. ishoeyi"; including genes likely leading to ammonification. As expected, the sulfur-oxidation pathway reported for other sulfur-oxidizing bacteria were deduced and also, key inorganic and organic carbon acquisition related genes were identified. Unexpectedly, the genome of "Ca. V. ishoeyi" contained numerous CRISPR repeats and an I-F CRISPR-Cas type system gene coding array. Findings further show that, as a member of an eons-old marine ecosystem, "Ca. V. ishoeyi" contains the needed metabolic plasticity for life in an increasingly oxygenated and variable ocean.

  6. Removal of ammonia solutions used in catalytic wet oxidation processes.

    Science.gov (United States)

    Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

    2003-08-01

    Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

  7. Hydrogen sulfide oxidation without oxygen - oxidation products and pathways

    International Nuclear Information System (INIS)

    Fossing, H.

    1992-01-01

    Hydrogen sulfide oxidation was studied in anoxic marine sediments-both in undisturbed sediment cores and in sediment slurries. The turn over of hydrogen sulfide was followed using 35 S-radiolabeled hydrogen sulfide which was injected into the sediment. However, isotope exchange reactions between the reduced sulfur compounds, in particular between elemental sulfur and hydrogen sulfide, influenced on the specific radioactivity of these pools. It was, therefore, not possible to measure the turn over rates of the reduced sulfur pools by the radiotracer technique but merely to use the radioisotope to demonstrate some of the oxidation products. Thiosulfate was one important intermediate in the anoxic oxidation of hydrogen sulfide and was continuously turned over by reduction, oxidation and disproportionation. The author discusses the importance of isotope exchange and also presents the results from experiments in which both 35 S-radiolabeled elemental sulfur, radiolabeled hydrogen sulfide and radiolabeled thiosulfate were used to study the intermediates in the oxidative pathways of the sulfur cycle

  8. Controls of nitrite oxidation in ammonia-removing biological air filters

    DEFF Research Database (Denmark)

    Juhler, Susanne; Ottosen, Lars Ditlev Mørck; Nielsen, Lars Peter

    2008-01-01

    in accumulation of nitrate rather than nitrite and a significant decline in pH. As a consequence, ammonia is removed more efficiently, but heterotrophic oxidation of odorous compounds might be inhibited.  To identify the controlling mechanisms of nitrite oxidation, full-scale biological air filters were...... activity resulting in a lowered pH and thus a decreased FA concentration, promoting further growth of NOB. Yet, in some cases a situation with a nitrate-to-nitrite ratio of 1 and moderate pH remained stable even under varying air load and water supply, suggesting that additional mechanisms were involved......In biological air filters ammonia is removed due to the action of Ammonia Oxidizing Bacteria (AOB) resulting in nitrite accumulation exceeding 100 mM. Among filters treating exhaust air from pig facilities successful establishment of Nitrite Oxidizing Bacteria (NOB) sometimes occurs, resulting...

  9. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur.

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    More than 170 wet scrubber systems applied, to 72,000 MW of U.S., coal-fired, utility boilers are in operation or under construction. In these systems, the sulfur dioxide removed from the boiler flue gas is permanently bound to a sorbent material, such as lime or limestone. The sulfated sorbent must be disposed of as a waste product or, in some cases, sold as a byproduct (e.g. gypsum). Due to the abundance and low cost of naturally occurring gypsum, and the costs associated with producing an industrial quality product, less than 7% of these scrubbers are configured to produce usable gypsum (and only 1% of all units actually sell the byproduct). The disposal of solid waste from each of these scrubbers requires a landfill area of approximately 200 to 400 acres. In the U.S., a total of 19 million tons of disposable FGD byproduct are produced, transported and disposed of in landfills annually. The use of regenerable sorbent technologies has the potential to reduce or eliminate solid waste production, transportation and disposal. In a regenerable sorbent system, the sulfur dioxide in the boiler flue gas is removed by the sorbent in an adsorber. The S0{sub 2}s subsequently released, in higher concentration, in a regenerator. All regenerable systems produce an off-gas stream from the regenerator that must be processed further in order to obtain a salable byproduct, such as elemental sulfur, sulfuric acid or liquid S0{sub 2}.

  10. Method for combined removal of mercury and nitrogen oxides from off-gas streams

    Science.gov (United States)

    Mendelsohn, Marshall H [Downers Grove, IL; Livengood, C David [Lockport, IL

    2006-10-10

    A method for removing elemental Hg and nitric oxide simultaneously from a gas stream is provided whereby the gas stream is reacted with gaseous chlorinated compound to convert the elemental mercury to soluble mercury compounds and the nitric oxide to nitrogen dioxide. The method works to remove either mercury or nitrogen oxide in the absence or presence of each other.

  11. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    Science.gov (United States)

    Sundararaman, Ramanathan

    Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

  12. The uptake and excretion of partially oxidized sulfur expands the repertoire of energy resources metabolized by hydrothermal vent symbioses.

    Science.gov (United States)

    Beinart, R A; Gartman, A; Sanders, J G; Luther, G W; Girguis, P R

    2015-05-07

    Symbiotic associations between animals and chemoautotrophic bacteria crowd around hydrothermal vents. In these associations, symbiotic bacteria use chemical reductants from venting fluid for the energy to support autotrophy, providing primary nutrition for the host. At vents along the Eastern Lau Spreading Center, the partially oxidized sulfur compounds (POSCs) thiosulfate and polysulfide have been detected in and around animal communities but away from venting fluid. The use of POSCs for autotrophy, as an alternative to the chemical substrates in venting fluid, could mitigate competition in these communities. To determine whether ESLC symbioses could use thiosulfate to support carbon fixation or produce POSCs during sulfide oxidation, we used high-pressure, flow-through incubations to assess the productivity of three symbiotic mollusc genera-the snails Alviniconcha spp. and Ifremeria nautilei, and the mussel Bathymodiolus brevior-when oxidizing sulfide and thiosulfate. Via the incorporation of isotopically labelled inorganic carbon, we found that the symbionts of all three genera supported autotrophy while oxidizing both sulfide and thiosulfate, though at different rates. Additionally, by concurrently measuring their effect on sulfur compounds in the aquaria with voltammetric microelectrodes, we showed that these symbioses excreted POSCs under highly sulfidic conditions, illustrating that these symbioses could represent a source for POSCs in their habitat. Furthermore, we revealed spatial disparity in the rates of carbon fixation among the animals in our incubations, which might have implications for the variability of productivity in situ. Together, these results re-shape our thinking about sulfur cycling and productivity by vent symbioses, demonstrating that thiosulfate may be an ecologically important energy source for vent symbioses and that they also likely impact the local geochemical regime through the excretion of POSCs.

  13. Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

    Science.gov (United States)

    Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

    2014-10-21

    Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously

  14. Continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process: An efficient diesel treatment by injection of the aqueous phase.

    Science.gov (United States)

    Rahimi, Masoud; Shahhosseini, Shahrokh; Movahedirad, Salman

    2017-11-01

    A new continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process was developed in order to decrease energy and aqueous phase consumption. In this process the aqueous phase is injected below the horn tip leading to enhanced mixing of the phases. Diesel fuel as the oil phase with sulfur content of 1550ppmw and an appropriate mixture of hydrogen peroxide and formic acid as the aqueous phase were used. At the first step, the optimized condition for the sulfur removal has been obtained in the batch mode operation. Hence, the effect of more important oxidation parameters; oxidant-to-sulfur molar ratio, acid-to-sulfur molar ratio and sonication time were investigated. Then the optimized conditions were obtained using Response Surface Methodology (RSM) technique. Afterwards, some experiments corresponding to the best batch condition and also with objective of minimizing the residence time and aqueous phase to fuel volume ratio have been conducted in a newly designed double-compartment reactor with injection of the aqueous phase to evaluate the process in a continuous flow operation. In addition, the effect of nozzle diameter has been examined. Significant improvement on the sulfur removal was observed specially in lower sonication time in the case of dispersion method in comparison with the conventional contact between two phases. Ultimately, the flow pattern induced by ultrasonic device, and also injection of the aqueous phase were analyzed quantitatively and qualitatively by capturing the sequential images. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Sulfur metabolism in the extreme acidophile Acidithiobacillus caldus

    Directory of Open Access Journals (Sweden)

    Stefanie eMangold

    2011-02-01

    Full Text Available Given the challenges to life at low pH, an analysis of inorganic sulfur compound oxidation was initiated in the chemolithoautotrophic extremophile Acidithiobacillus caldus. A. caldus is able to metabolize elemental sulfur and a broad range of inorganic sulfur compounds. It has been implicated in the production of environmentally damaging acidic solutions as well as participating in industrial bioleaching operations where it forms part of microbial consortia used for the recovery of metal ions. Based upon the recently published A. caldus type strain genome sequence, a bioinformatic reconstruction of elemental sulfur and inorganic sulfur compound metabolism predicted genes included: sulfide quinone reductase (sqr, tetrathionate hydrolase (tth, two sox gene clusters potentially involved in thiosulfate oxidation (soxABXYZ, sulfur oxygenase reductase (sor, and various electron transport components. RNA transcript profiles by semi-quantitative reverse transcription PCR suggested up-regulation of sox genes in the presence of tetrathionate. Extensive gel based proteomic comparisons of total soluble and membrane enriched protein fractions during growth on elemental sulfur and tetrathionate identified differential protein levels from the two Sox clusters as well as several chaperone and stress proteins up-regulated in the presence of elemental sulfur. Proteomics results also suggested the involvement of heterodisulfide reductase (HdrABC in A. caldus inorganic sulfur compound metabolism. A putative new function of Hdr in acidophiles is discussed. Additional proteomic analysis evaluated protein expression differences between cells grown attached to solid, elemental sulfur versus planktonic cells. This study has provided insights into sulfur metabolism of this acidophilic chemolithotroph and gene expression during attachment to solid elemental sulfur.

  16. Selective Sulfidation of Lead Smelter Slag with Sulfur

    Science.gov (United States)

    Han, Junwei; Liu, Wei; Wang, Dawei; Jiao, Fen; Qin, Wenqing

    2016-02-01

    The selective sulfidation of lead smelter slag with sulfur was studied. The effects of temperature, sulfur dosage, carbon, and Na salts additions were investigated based on thermodynamic calculation. The results indicated that more than 96 pct of zinc in the slag could be converted into sulfides. Increasing temperature, sulfur dosage, or Na salts dosage was conducive to the sulfidation of the zinc oxides in the slag. High temperature and excess Na salts would result in the more consumption of carbon and sulfur. Carbon addition not only promoted the selective sulfidation but reduced the sulfur dosage and eliminated the generation of SO2. Iron oxides had a buffering role on the sulfur efficient utilization. The transformation of sphalerite to wurtzite was feasible under reducing condition at high temperature, especially above 1273 K (1000 °C). The growth of ZnS particles largely depended upon the roasting temperature. They were significantly increased when the temperature was above 1273 K (1000 °C), which was attributed to the formation of a liquid phase.

  17. Application of Iron Oxide Nano materials for the Removal of Heavy Metals

    International Nuclear Information System (INIS)

    Dave, P.N.; Chopda, L.V.

    2014-01-01

    In the 21st century water polluted by heavy metal is one of the environment problems. Various methods for removal of the heavy metal ions from the water have extensively been studied. Application of iron oxide nana particles based nano materials for removal of heavy metals is well-known adsorbents for remediation of water. Due to its important physiochemical property, inexpensive method and easy regeneration in the presence of external magnetic field make them more attractive toward water purification. Surface modification strategy of iron oxide nanoparticles is also used for the remediation of water increases the efficiency of iron oxide for the removal of the heavy metal ions from the aqueous system.

  18. Selective catalytic oxidation: a new catalytic approach to the desulfurization of natural gas and liquid petroleum gas for fuel cell reformer applications

    Science.gov (United States)

    Lampert, J.

    In both natural gas and liquid petroleum gas (LPG), sulfur degrades the performance of the catalysts used in fuel reformers and fuel cells. In order to improve system performance, the sulfur must be removed to concentrations of less than 200 ppbv (in many applications to less than 20 ppbv) before the fuel reforming operation. Engelhard Corporation presents a unique approach to the desulfurization of natural gas and LPG. This new method catalytically converts the organic and inorganic sulfur species to sulfur oxides. The sulfur oxides are then adsorbed on a high capacity adsorbent. The sulfur compounds in the fuel are converted to sulfur oxides by combining the fuel with a small amount of air. The mixture is then heated from 250 to 270 °C, and contacted with a monolith supported sulfur tolerant catalyst at atmospheric pressure. When Engelhard Corporation demonstrated this catalytic approach in the laboratory, the result showed sulfur breakthrough to be less than 10 ppbv in the case of natural gas, and less than 150 ppbv for LPG. We used a simulated natural gas and LPG mixture, doped with a 50-170 ppmv sulfur compound containing equal concentrations of COS, ethylmercaptan, dimethylsulfide, methylethylsulfide and tetrahydrothiophene. There is no need for recycled H 2 as in the case for hydrodesulfurization.

  19. Ultra Low Sulfur Home Heating Oil Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Batey, John E. [Energy Research Center, Inc., Easton, CT (United States); McDonald, Roger [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-30

    This Ultra Low Sulfur (ULS) Home Heating Oil Demonstration Project was funded by the New York State Energy Research and Development Authority (NYSERDA) and has successfully quantified the environmental and economic benefits of switching to ULS (15 PPM sulfur) heating oil. It advances a prior field study of Low Sulfur (500 ppm sulfur) heating oil funded by NYSERDA and laboratory research conducted by Brookhaven National Laboratory (BNL) and Canadian researchers. The sulfur oxide and particulate matter (PM) emissions are greatly reduced as are boiler cleaning costs through extending cleaning intervals. Both the sulfur oxide and PM emission rates are directly related to the fuel oil sulfur content. The sulfur oxide and PM emission rates approach near-zero levels by switching heating equipment to ULS fuel oil, and these emissions become comparable to heating equipment fired by natural gas. This demonstration project included an in-depth review and analysis of service records for both the ULS and control groups to determine any difference in the service needs for the two groups. The detailed service records for both groups were collected and analyzed and the results were entered into two spreadsheets that enabled a quantitative side-by-side comparison of equipment service for the entire duration of the ULS test project. The service frequency for the ULS and control group were very similar and did indicate increased service frequency for the ULS group. In fact, the service frequency with the ULS group was slightly less (7.5 percent) than the control group. The only exception was that three burner fuel pump required replacement for the ULS group and none were required for the control group.

  20. Studies on nitric oxide removal in simulated gas compositions under plasma-dielectric/catalytic discharges

    International Nuclear Information System (INIS)

    Rajanikanth, B.S.; Rout, Satyabrata

    2001-01-01

    Application of pulsed electrical discharges for gas cleaning is gaining prominence, mainly from the energy consideration point of view. This present paper presents recent work on applying the electrical discharge plasma technology for treating gaseous pollutants, in general, and nitric oxide, in particular, as this is one of the major contributors to air pollution. The present work focuses attention on pulsed electrical discharge technique for nitric oxide removal from simulated gas compositions and study of effect of packed dielectric pellets, with and without a coating of catalyst, on the removal process. Experiments were conducted in a cylindrical corona reactor energized by repetitive high voltage pulses. The effects of various parameters, viz. pulse voltage magnitude, pulse frequency, initial nitric oxide concentration and gas mixture composition on nitric oxide removal efficiency, are discussed. When the reactors were filled with different dielectric pellets like, barium titanate, alumina, and alumina coated with palladium catalyst, the improvement in nitric oxide removal efficiency is studied and discussed. The power dissipated in the reactor and the energy consumed per nitric oxide molecule removed was calculated. Further results and comparative study of various cases are presented in the paper

  1. Oxidative desulfurization of dibenzothiophene from model oil using ionic liquids as extracting agent

    Science.gov (United States)

    Taha, Mohd F.; Atikah, N.; Chong, F. K.; Shaharun, Maizatul S.

    2012-09-01

    The oxidative desulfurization of dibenzothiophene (DBT) from model oil (in n-dodecane) was carried out using ionic liquid as the extractant and catalyst, and hydrogen peroxide (H2O2) in combination with acetic acid (CH3COOH) and sulphuric acid (H2SO4) as the oxidant. The ionic liquids used were 1-butyl-3-methylimidazolium octyl sulphate ([Bmim][OcSO4]) and 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]). The effect of the amounts of H2O2 on oxidative desulphurization of model oil was first investigated without the usage of ionic liquids at room temperature. The results indicate that greater amount of H2O2 give higher desulfurization and the maximum desulfurization in this study, i.e. 34 %, was occurred when the molar ratio of H2O2 to sulfur was 5:1. With the usage of ionic liquid and the molar ratio of 5:1 (H2O2:sulfur), the efficiency of DBT removal from model oil was increased significantly in terms of percent removal and removal time. Ionic liquid of [Bmim][OcSO4] performed better than [Bmim][Ac] with 72 % DBT removal. When molar ratio of H2O2 to sulphur was 5:1, volume ratio of ionic liquid to model oil was 1:1 and mixing time was 60 min at room temperature. The results indicate the potential of ionic liquids as the extractant and catalyst for oxidative desulfurization of hydrocarbon fuels.

  2. Oxidative desulfurization of diesel with TBHP/isobutyl aldehyde/air oxidation system

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei; Wang, Chengyong; Lin, Peng; Lu, Xiaoping [Institute of Sonochemical Engineering, Nanjing University of Technology, Nanjing 210009, Jiangsu (China)

    2011-01-15

    Oxidative desulfurization of hydrogenation diesel (40 mL) was studied using air as oxidant, tert-butyl hydroperoxide (TBHP) as radical initiator at ambient pressure and moderate temperature in the presence of isobutyl aldehyde. TBHP could accelerate the production of carbonyl radical and its peroxidation. When the molar fraction of TBHP was 5 mmol, the conversion of DBT could reach 96.1% in the present of 20 mmol isobutyl aldehyde and air, which was more than that of 85.5% without initiator. The air was an effective oxidant and acetonitrile was an optimal solvent in this process. The sulfur content of the hydrogenation diesel could be reduced from 403 to 13 ppm (96.8% removed) under the synergistic effect of air, TBHP and isobutyl aldehyde. (author)

  3. Sulfur dioxide leaching of spent zinc-carbon-battery scrap

    Energy Technology Data Exchange (ETDEWEB)

    Avraamides, J.; Senanayake, G.; Clegg, R. [A.J. Parker Cooperative Research Centre for Hydrometallurgy, Murdoch University, Perth, WA 6150 (Australia)

    2006-09-22

    Zinc-carbon batteries, which contain around 20% zinc, 35% manganese oxides and 10% steel, are currently disposed after use as land fill or reprocessed to recover metals or oxides. Crushed material is subjected to magnetic separation followed by hydrometallurgical treatment of the non-magnetic material to recover zinc metal and manganese oxides. The leaching with 2M sulfuric acid in the presence of hydrogen peroxide recovers 93% Zn and 82% Mn at 25{sup o}C. Alkaline leaching with 6M NaOH recovers 80% zinc. The present study shows that over 90% zinc and manganese can be leached in 20-30min at 30{sup o}C using 0.1-1.0M sulfuric acid in the presence of sulfur dioxide. The iron extraction is sensitive to both acid concentration and sulfur dioxide flow rate. The effect of reagent concentration and particle size on the extraction of zinc, manganese and iron are reported. It is shown that the iron and manganese leaching follow a shrinking core kinetic model due to the formation of insoluble metal salts/oxides on the solid surface. This is supported by (i) the decrease in iron and manganese extraction from synthetic Fe(III)-Mn(IV)-Zn(II) oxide mixtures with increase in acid concentration from 1M to 2M, and (ii) the low iron dissolution and re-precipitation of dissolved manganese and zinc during prolonged leaching of battery scrap with low sulfur dioxide. (author)

  4. Sulfur emission from Victorian brown coal under pyrolysis, oxy-fuel combustion and gasification conditions.

    Science.gov (United States)

    Chen, Luguang; Bhattacharya, Sankar

    2013-02-05

    Sulfur emission from a Victorian brown coal was quantitatively determined through controlled experiments in a continuously fed drop-tube furnace under three different atmospheres: pyrolysis, oxy-fuel combustion, and carbon dioxide gasification conditions. The species measured were H(2)S, SO(2), COS, CS(2), and more importantly SO(3). The temperature (873-1273 K) and gas environment effects on the sulfur species emission were investigated. The effect of residence time on the emission of those species was also assessed under oxy-fuel condition. The emission of the sulfur species depended on the reaction environment. H(2)S, SO(2), and CS(2) are the major species during pyrolysis, oxy-fuel, and gasification. Up to 10% of coal sulfur was found to be converted to SO(3) under oxy-fuel combustion, whereas SO(3) was undetectable during pyrolysis and gasification. The trend of the experimental results was qualitatively matched by thermodynamic predictions. The residence time had little effect on the release of those species. The release of sulfur oxides, in particular both SO(2) and SO(3), is considerably high during oxy-fuel combustion even though the sulfur content in Morwell coal is only 0.80%. Therefore, for Morwell coal utilization during oxy-fuel combustion, additional sulfur removal, or polishing systems will be required in order to avoid corrosion in the boiler and in the CO(2) separation units of the CO(2) capture systems.

  5. Microaeration for hydrogen sulfide removal in UASB reactor.

    Science.gov (United States)

    Krayzelova, Lucie; Bartacek, Jan; Kolesarova, Nina; Jenicek, Pavel

    2014-11-01

    The removal of hydrogen sulfide from biogas by microaeration was studied in Up-flow Anaerobic Sludge Blanket (UASB) reactors treating synthetic brewery wastewater. A fully anaerobic UASB reactor served as a control while air was dosed into a microaerobic UASB reactor (UMSB). After a year of operation, sulfur balance was described in both reactors. In UASB, sulfur was mainly presented in the effluent as sulfide (49%) and in biogas as hydrogen sulfide (34%). In UMSB, 74% of sulfur was detected in the effluent (41% being sulfide and 33% being elemental sulfur), 10% accumulated in headspace as elemental sulfur and 9% escaped in biogas as hydrogen sulfide. The efficiency of hydrogen sulfide removal in UMSB was on average 73%. Microaeration did not cause any decrease in COD removal or methanogenic activity in UMSB and the elemental sulfur produced by microaeration did not accumulate in granular sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. The Fe removal in pyrophyllite by physical method

    Science.gov (United States)

    Cho, Kanghee; Jo, Jiyu; Bak, GeonYeong; Choi, NagChoul; Park*, CheonYoung

    2015-04-01

    The presence of Fe in ingredient material such as limestone, borax and pyrophyllite can prevent their use mainly in the glass fiber manufacturing industry. The red to yellow pigmentation in pyrophyllite is mainly due to the associated oxides and sulfides of Fe such as hematite, pyrite, etc. The removal of Fe in the pyrophyllite was investigated using high frequency treatment and magnetic separation under various alumina grades in pyrophyllite. The hematite and pyrite were observed in the pyrophyllite from photomicrograph and XRD analysis results. On the decrease of Al2O3 content in pyrophyllite was showed that SiO2, Fe2O3 and TiO2 content were increased by XRF analysis. The high frequency treatment experiment for the pyrophyllite showed that the (1) pyrite phase was transformed hematite and magnetite, (2) mass loss of the sample by volatilization of included sulfur(S) in pyrite. The results of magnetic separation for treated sample by high frequency were identified that Fe removal percent were in the range of 97.6~98.8%. This study demonstrated that physical method (high frequency treatment and magnetic separation) was effective for the removal of Fe in pyrophyllite. This subject is supported by Korea Ministry of Environment(MOE) as "Advanced Technology Program for Environmental Industry".

  7. The Global Redox Responding RegB/RegA Signal Transduction System Regulates the Genes Involved in Ferrous Iron and Inorganic Sulfur Compound Oxidation of the Acidophilic Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    Danielle Moinier

    2017-07-01

    Full Text Available The chemical attack of ore by ferric iron and/or sulfuric acid releases valuable metals. The products of these reactions are recycled by iron and sulfur oxidizing microorganisms. These acidophilic chemolithotrophic prokaryotes, among which Acidithiobacillus ferrooxidans, grow at the expense of the energy released from the oxidation of ferrous iron and/or inorganic sulfur compounds (ISCs. In At. ferrooxidans, it has been shown that the expression of the genes encoding the proteins involved in these respiratory pathways is dependent on the electron donor and that the genes involved in iron oxidation are expressed before those responsible for ISCs oxidation when both iron and sulfur are present. Since the redox potential increases during iron oxidation but remains stable during sulfur oxidation, we have put forward the hypothesis that the global redox responding two components system RegB/RegA is involved in this regulation. To understand the mechanism of this system and its role in the regulation of the aerobic respiratory pathways in At. ferrooxidans, the binding of different forms of RegA (DNA binding domain, wild-type, unphosphorylated and phosphorylated-like forms of RegA on the regulatory region of different genes/operons involved in ferrous iron and ISC oxidation has been analyzed. We have shown that the four RegA forms are able to bind specifically the upstream region of these genes. Interestingly, the phosphorylation of RegA did not change its affinity for its cognate DNA. The transcriptional start site of these genes/operons has been determined. In most cases, the RegA binding site(s was (were located upstream from the −35 (or −24 box suggesting that RegA does not interfere with the RNA polymerase binding. Based on the results presented in this report, the role of the RegB/RegA system in the regulation of the ferrous iron and ISC oxidation pathways in At. ferrooxidans is discussed.

  8. The Global Redox Responding RegB/RegA Signal Transduction System Regulates the Genes Involved in Ferrous Iron and Inorganic Sulfur Compound Oxidation of the Acidophilic Acidithiobacillus ferrooxidans

    Science.gov (United States)

    Moinier, Danielle; Byrne, Deborah; Amouric, Agnès; Bonnefoy, Violaine

    2017-01-01

    The chemical attack of ore by ferric iron and/or sulfuric acid releases valuable metals. The products of these reactions are recycled by iron and sulfur oxidizing microorganisms. These acidophilic chemolithotrophic prokaryotes, among which Acidithiobacillus ferrooxidans, grow at the expense of the energy released from the oxidation of ferrous iron and/or inorganic sulfur compounds (ISCs). In At. ferrooxidans, it has been shown that the expression of the genes encoding the proteins involved in these respiratory pathways is dependent on the electron donor and that the genes involved in iron oxidation are expressed before those responsible for ISCs oxidation when both iron and sulfur are present. Since the redox potential increases during iron oxidation but remains stable during sulfur oxidation, we have put forward the hypothesis that the global redox responding two components system RegB/RegA is involved in this regulation. To understand the mechanism of this system and its role in the regulation of the aerobic respiratory pathways in At. ferrooxidans, the binding of different forms of RegA (DNA binding domain, wild-type, unphosphorylated and phosphorylated-like forms of RegA) on the regulatory region of different genes/operons involved in ferrous iron and ISC oxidation has been analyzed. We have shown that the four RegA forms are able to bind specifically the upstream region of these genes. Interestingly, the phosphorylation of RegA did not change its affinity for its cognate DNA. The transcriptional start site of these genes/operons has been determined. In most cases, the RegA binding site(s) was (were) located upstream from the −35 (or −24) box suggesting that RegA does not interfere with the RNA polymerase binding. Based on the results presented in this report, the role of the RegB/RegA system in the regulation of the ferrous iron and ISC oxidation pathways in At. ferrooxidans is discussed. PMID:28747899

  9. Kinetic effects of sulfur oxidation on catalytic nitrile hydration: nitrile hydratase insights from bioinspired ruthenium(II) complexes.

    Science.gov (United States)

    Kumar, Davinder; Nguyen, Tho N; Grapperhaus, Craig A

    2014-12-01

    Kinetic investigations inspired by the metalloenzyme nitrile hydratase were performed on a series of ruthenium(II) complexes to determine the effect of sulfur oxidation on catalytic nitrile hydration. The rate of benzonitrile hydration was quantified as a function of catalyst, nitrile, and water concentrations. Precatalysts L(n)RuPPh3 (n = 1-3; L(1) = 4,7-bis(2'-methyl-2'-mercapto-propyl)-1-thia-4,7-diazacyclononane; L(2) = 4-(2'-methyl-2'-sulfinatopropyl)-7-(2'-methyl-2'-mercapto-propyl)-1-thia-4,7-diazacyclononane; L(3) = 4-(2'-methyl-2'-sulfinatopropyl)-7-(2'-methyl-2'-sulfenato-propyl)-1-thia-4,7-diazacyclononane) were activated by substitution of triphenylphosphine with substrate in hot dimethylformamide solution. Rate measurements are consistent with a dynamic equilibrium between inactive aqua (L(n)Ru-OH2) and active nitrile (L(n)Ru-NCR) derivatives with K = 21 ± 1, 9 ± 0.9, and 23 ± 3 for L(1) to L(3), respectively. Subsequent hydration of the L(n)Ru-NCR intermediate yields the amide product with measured hydration rate constants (k's) of 0.37 ± 0.01, 0.82 ± 0.07, and 1.59 ± 0.12 M(-1) h(-1) for L(1) to L(3), respectively. Temperature dependent studies reveal that sulfur oxidation lowers the enthalpic barrier by 27 kJ/mol, but increases the entropic barrier by 65 J/(mol K). Density functional theory (DFT) calculations (B3LYP/LanL2DZ (Ru); 6-31G(d) (all other atoms)) support a nitrile bound catalytic cycle with lowering of the reaction barrier as a consequence of sulfur oxidation through enhanced nitrile binding and attack of the water nucleophile through a highly organized transition state.

  10. Removing sulphur oxides from a fluid stream

    Science.gov (United States)

    Katz, Torsten; Riemann, Christian; Bartling, Karsten; Rigby, Sean Taylor; Coleman, Luke James Ivor; Lail, Marty Alan

    2014-04-08

    A process for removing sulphur oxides from a fluid stream, such as flue gas, comprising: providing a non-aqueous absorption liquid containing at least one hydrophobic amine, the liquid being incompletely miscible with water; treating the fluid stream in an absorption zone with the non-aqueous absorption liquid to transfer at least part of the sulphur oxides into the non-aqueous absorption liquid and to form a sulphur oxide-hydrophobic amine-complex; causing the non-aqueous absorption liquid to be in liquid-liquid contact with an aqueous liquid whereby at least part of the sulphur oxide-hydrophobic amine-complex is hydrolyzed to release the hydrophobic amine and sulphurous hydrolysis products, and at least part of the sulphurous hydrolysis products is transferred into the aqueous liquid; separating the aqueous liquid from the non-aqueous absorption liquid. The process mitigates absorbent degradation problems caused by sulphur dioxide and oxygen in flue gas.

  11. Ultrasound-assisted oxidative desulfurization of liquid fuels and its industrial application.

    Science.gov (United States)

    Wu, Zhilin; Ondruschka, Bernd

    2010-08-01

    Latest environmental regulations require a very deep desulfurization to meet the ultra-low sulfur diesel (ULSD, 15 ppm sulfur) specifications. Due to the disadvantages of hydrotreating technology on the slashing production conditions, costs and safety as well as environmental protection, the ultrasound-assisted oxidative desulfurization (UAOD) as an alternative technology has been developed. UAOD process selectively oxidizes sulfur in common thiophenes in diesel to sulfoxides and sulfones which can be removed via selective adsorption or extractant. SulphCo has successfully used a 5000 barrel/day mobile "Sonocracking" unit to duplicate on a commercial scale its proprietary process that applies ultrasonics at relatively low temperatures and pressures. The UAOD technology estimate capital costs less than half the cost of a new high-pressure hydrotreater. The physical and chemical mechanisms of UAOD process are illustrated, and the effective factors, such as ultrasonic frequency and power, oxidants, catalysts, phase-transfer agent, extractant and adsorbent, on reaction kinetics and product recovery are discussed in this review. Copyright 2009 Elsevier B.V. All rights reserved.

  12. Oxidation of SO2 by stabilized Criegee intermediate (sCI radicals as a crucial source for atmospheric sulfuric acid concentrations

    Directory of Open Access Journals (Sweden)

    M. Boy

    2013-04-01

    Full Text Available The effect of increased reaction rates of stabilized Criegee intermediates (sCIs with SO2 to produce sulfuric acid is investigated using data from two different locations, SMEAR II, Hyytiälä, Finland, and Hohenpeissenberg, Germany. Results from MALTE, a zero-dimensional model, show that using previous values for the rate coefficients of sCI + SO2, the model underestimates gas phase H2SO4 by up to a factor of two when compared to measurements. Using the rate coefficients recently calculated by Mauldin et al. (2012 increases sulfuric acid by 30–40%. Increasing the rate coefficient for formaldehyde oxide (CH2OO with SO2 according to the values recommended by Welz et al. (2012 increases the H2SO4 yield by 3–6%. Taken together, these increases lead to the conclusion that, depending on their concentrations, the reaction of stabilized Criegee intermediates with SO2 could contribute as much as 33–46% to atmospheric sulfuric acid gas phase concentrations at ground level. Using the SMEAR II data, results from SOSA, a one-dimensional model, show that the contribution from sCI reactions to sulfuric acid production is most important in the canopy, where the concentrations of organic compounds are the highest, but can have significant effects on sulfuric acid concentrations up to 100 m. The recent findings that the reaction of sCI + SO2 is much faster than previously thought together with these results show that the inclusion of this new oxidation mechanism could be crucial in regional as well as global models.

  13. Understanding the effects of sulfur on mercury capture from coal-fired utility flue gases

    Energy Technology Data Exchange (ETDEWEB)

    Morris, E.A.; Morita, K.; Jia, C.Q. [University of Toronto, Toronto, ON (Canada)

    2010-07-01

    Coal combustion continues to be a major source of energy throughout the world and is the leading contributor to anthropogenic mercury emissions. Effective control of these emissions requires a good understanding of how other flue gas constituents such as sulfur dioxide (SO{sub 2}) and sulfur trioxide (SO{sub 3}) may interfere in the removal process. Most of the current literature suggests that SO{sub 2} hinders elemental mercury (Hg{sup 0}) oxidation by scavenging oxidizing species such as chlorine (Cl2) and reduces the overall efficiency of mercury capture, while there is evidence to suggest that SO{sub 2} with oxygen (O{sub 2}) enhances Hg{sup 0} oxidation by promoting Cl2 formation below 100{sup o}C. However, studies in which SO{sub 2} was shown to have a positive correlation with Hg{sup 0} oxidation in full-scale utilities indicate that these interactions may be heavily dependent on operating conditions, particularly chlorine content of the coal and temperature. While bench-scale studies explicitly targeting SO{sub 3} are scarce, the general consensus among full-scale coal-fired utilities is that its presence in flue gas has a strong negative correlation with mercury capture efficiency. The exact reason behind this observed correlation is not completely clear, however. While SO{sub 3} is an inevitable product of SO{sub 2} oxidation by O{sub 2}, a reaction that hinders Hg{sup 0} oxidation, it readily reacts with water vapor, forms sulfuric acid (H{sub 2 }SO{sub 4}) at the surface of carbon, and physically blocks active sites of carbon. On the other hand, H{sub 2}SO{sub 4} on carbon surfaces may increase mercury capacity either through the creation of oxidation sites on the carbon surface or through a direct reaction of mercury with the acid. However, neither of these beneficial impacts is expected to be of practical significance for an activated carbon injection system in a real coal-fired utility flue gas.

  14. Transformation and removal of arsenic in groundwater by sequential anodic oxidation and electrocoagulation

    Science.gov (United States)

    Zhang, Peng; Tong, Man; Yuan, Songhu; Liao, Peng

    2014-08-01

    Oxidation of As(III) to As(V) is generally essential for the efficient remediation of As(III)-contaminated groundwater. The performance and mechanisms of As(III) oxidation by an as-synthesized active anode, SnO2 loaded onto Ti-based TiO2 nanotubes (Ti/TiO2NTs/Sb-SnO2), were investigated. The subsequent removal of total arsenic by electrocoagulation (EC) was further tested. The Ti/TiO2NTs/Sb-SnO2 anode showed a high and lasting electrochemical activity for As(III) oxidation. 6.67 μM As(III) in synthetic groundwater was completely oxidized to As(V) within 60 min at 50 mA. Direct electron transfer was mainly responsible at the current below 30 mA, while hydroxyl radicals contributed increasingly with the increase in the current above 30 mA. As(III) oxidation was moderately inhibited by the presence of bicarbonate (20 mM), while was dramatically increased with increasing the concentration of chloride (0-10 mM). After the complete oxidation of As(III) to As(V), total arsenic was efficiently removed by EC in the same reactor by reversing electrode polarity. The removal efficiency increased with increasing the current but decreased by the presence of phosphate and silica. Anodic oxidation represents an effective pretreatment approach to increasing EC removal of As(III) in groundwater under O2-limited conditions.

  15. Simultaneous removal of SO{sub 2} and NO{sub x} by microwave with potassium permanganate over zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Zai-shan; Niu, He-jingying; Ji, Yong-feng [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2009-02-15

    Simultaneous sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) removal from flue gas can be achieved with high efficiency by microwave with potassium permanganate (KMnO{sub 4}) over zeolite. The experimental results showed that the microwave reactor could be used to oxidation of SO{sub 2} to sulfate with the best desulfurization efficiency of 96.8% and oxidize NO{sub x} to nitrates with the best NO{sub x} removal efficiency of 98.4%. Microwave accentuates catalytic oxidation treatment, and microwave addition can increase the SO{sub 2} and NO{sub x} removal efficiency by 7.2% and 12.2% separately. The addition of zeolite to microwave potassium permanganate increases from 16.5% to 43.5% the microwave removal efficiency for SO{sub 2}, and the NO{sub x} removal efficiency from 85.6% to 98.2%. The additional use of potassium permanganate to the microwave zeolite leads to the enhancement of SO{sub 2} removal efficiency up from 53.9% to 95%, and denitrification efficiency up from 85.6% to 98.2%. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and denitrification are 259 W and 0.357 s, respectively. SO{sub 2} and NO{sub x} were rapidly oxidized in microwave induced catalytic oxidation reaction using potassium permanganate with zeolite being the catalyst and microwave absorbent. (author)

  16. Comparative Genomics of Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Ussery, David; Davenport, C; Tümmler, B

    2010-01-01

    Eleven completely sequenced Chlorobi genomes were compared in oligonucleotide usage, gene contents, and synteny. The green sulfur bacteria (GSB) are equipped with a core genome that sustains their anoxygenic phototrophic lifestyle by photosynthesis, sulfur oxidation, and CO(2) fixation. Whole...... weight of 10(6), and are probably instrumental for the bacteria to generate their own intimate (micro)environment....

  17. Study of the removal of cesium from aqueous solutions by graphene oxide

    International Nuclear Information System (INIS)

    Bueno, Vanessa N.; Rodrigues, Debora F.; Vitta, Patricia B. Di

    2013-01-01

    Graphene oxide, used in this work, was synthesized from the oxidation of graphite by Hummer method. The experiments were performed in batch and analyzed for the following parameters: contact time, pH, cesium ion concentration in aqueous solution and removing capacity of the graphene oxide. After the experiments the samples were vacuum filtered and the remaining cesium in solution was quantified by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The equilibrium was reached after 60 minutes of contact in neutral solution. The percentage of removal was around 80%

  18. Enhancement of Oxidative Desulfurization Performance over UiO-66(Zr) by Titanium Ion Exchange.

    Science.gov (United States)

    Ye, Gan; Qi, Hui; Li, Xiaolin; Leng, Kunyue; Sun, Yinyong; Xu, Wei

    2017-07-19

    Oxidative desulfurization is considered to be one of the most promising methods for producing ultra-low-sulfur fuels because it can effectively remove refractory sulfur-containing aromatic compounds under mild conditions. In this work, the oxidative desulfurization performance over UiO-66(Zr) is greatly enhanced by Ti ion exchange. This strategy is not only efficient for UiO-66(Zr) with crystal defects but also for UiO-66(Zr) with high crystallinity. In particular, the performance of UiO-66(Zr) with high crystallinity in the oxidative desulfurization of dibenzothiophene can be improved more than 11-fold, which can be mainly attributed to the introduction of active Ti sites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Oxidation of alginate and pectate biopolymers by cerium(IV) in perchloric and sulfuric acid solutions: A comparative kinetic and mechanistic study.

    Science.gov (United States)

    Fawzy, Ahmed

    2016-03-15

    The kinetics of oxidation of alginate (Alg) and pectate (Pec) carbohydrate biopolymers was studied by spectrophotometry in aqueous perchloric and sulfuric acid solutions at fixed ionic strengths and temperature. In both acids, the reactions showed a first order dependence on [Ce(IV)], whereas the orders with respect to biopolymer concentrations are less than unity. In perchloric acid, the reactions exhibited less than unit orders with respect to [H(+)] whereas those proceeded in sulfuric acid showed negative fractional-first order dependences on [H(+)]. The effect of ionic strength and dielectric constant was studied. Probable mechanistic schemes for oxidation reactions were proposed. In both acids, the final oxidation products were characterized as mono-keto derivatives of both biopolymers. The activation parameters with respect to the slow step of the mechanisms were computed and discussed. The rate laws were derived and the reaction constants involved in the different steps of the mechanisms were calculated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Sulfur poisoning of Ni/Gadolinium-doped ceria anodes: A long-term study outlining stable solid oxide fuel cell operation

    Science.gov (United States)

    Riegraf, Matthias; Zekri, Atef; Knipper, Martin; Costa, Rémi; Schiller, Günter; Friedrich, K. Andreas

    2018-03-01

    This work presents an analysis of the long-term behavior of nickel/gadolinium-doped ceria (CGO) anode-based solid oxide fuel cells (SOFC) under sulfur poisoning conditions. A parameter study of sulfur-induced irreversible long-term degradation of commercial, high-performance single cells was carried out at 900 °C for different H2/N2/H2S fuel gas atmospheres, current densities and Ni/CGO anodes. The poisoning periods of the cells varied from 200 to 1500 h. The possibility of stable long-term Ni/CGO anode operation under sulfur exposure is established and the critical operating regime is outlined. Depending on the operating conditions, two degradation phenomena can be observed. Small degradation of the ohmic resistance was witnessed for sulfur exposure times of approximately 1000 h. Moreover, degradation of the anode charge transfer resistance was observed to be triggered by the combination of a small anodic potential step and high sulfur coverage on Ni. The microstructural evolution of altered Ni/CGO anodes was examined post-mortem by means of SEM and FIB/SEM, and is correlated to the anode performance degradation under critical operating conditions, establishing Ni depletion, porosity increase and a tripe phase boundary density decrease in the anode functional layer. It is shown that short-term sulfur poisoning behavior can be used to assess long-term stability.

  1. Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water.

    Science.gov (United States)

    Zhang, Ruifeng; Huang, Tinglin; Wen, Gang; Chen, Yongpan; Cao, Xin; Zhang, Beibei

    2017-07-19

    An iron-manganese co-oxide filter film (MeO x ) 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, MeO x was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeO x 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 MeO x 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 MeO x was formed by abiotic ways and the main elements on the surface of MeO x were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeO x as both ammonia molecules and ammonium ions and the active species of O₂ were possibly • O and O₂ - .

  2. Physiology and application of sulfur-reducing microorganisms from acidic environments

    NARCIS (Netherlands)

    Florentino, Anna Patrícya

    2017-01-01

    Sulfur cycle is one of the main geochemical cycles on Earth. Oxidation and reduction reactions of sulfur are mostly biotic and performed by microorganisms. In anaerobic conditions – marine and some freshwater systems, dissimilatory sulfur- and sulfate-reducing bacteria and archaea are key players

  3. Do constructed wetlands remove metals or increase metal bioavailability?

    Science.gov (United States)

    Xu, Xiaoyu; Mills, Gary L

    2018-07-15

    The H-02 wetland was constructed to treat building process water and storm runoff water from the Tritium Processing Facility on the Department of Energy's Savannah River Site (Aiken, SC). Monthly monitoring of copper (Cu) and zinc (Zn) concentrations and water quality parameters in surface waters continued from 2014 to 2016. Metal speciation was modeled at each sampling occasion. Total Cu and Zn concentrations released to the effluent stream were below the NPDES limit, and the average removal efficiency was 65.9% for Cu and 71.1% for Zn. The metal-removal processes were found out to be seasonally regulated by sulfur cycling indicated by laboratory and model results. High temperature, adequate labile organic matter, and anaerobic conditions during the warm months (February to August) favored sulfate reduction that produced sulfide minerals to significantly remove metals. However, the dominant reaction in sulfur cycling shifted to sulfide oxidation during the cool months (September to next March). High concentrations of metal-organic complexes were observed, especially colloidal complexes of metal and fulvic acid (FA), demonstrating adsorption to organic matter became the primary process for metal removal. Meanwhile, the accumulation of metal-FA complexes in the wetland system will cause negative effects to the surrounding environment as they are biologically reactive, highly bioavailable, and can be easily taken up and transferred to ecosystems by trophic exchange. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. A broad spectrum catalytic system for removal of toxic organics from water by deep oxidation. 1998 annual progress report

    International Nuclear Information System (INIS)

    Sen, A.

    1998-01-01

    'Toxic organics and polymers pose a serious threat to the environment, especially when they are present in aquatic systems. The objective of the research is the design of practical procedures for the removal and/or recycling of such pollutants by oxidation. This report summarizes the work performed in the first one and half years of a three year project. The authors had earlier described a catalytic system for the deep oxidation of toxic organics, such as benzene, phenol and substituted phenols, aliphatic and aromatic halogenated compounds, organophosphorus, and organosulfur compounds [1]. In this system, metallic palladium was found to catalyze the oxidation of the substrate by dioxygen in aqueous medium at 80--100 C in the presence of carbon monoxide. For all the substrates examined, deep oxidation to carbon monoxide, carbon dioxide, and water occurred in high yields, resulting in up to several hundred turnovers over a 24 h period. Because of a pressing need for new procedures for the destruction of chemical warfare agents, the authors have examined in detail the deep oxidation of appropriate model compounds containing phosphorus-carbon and sulfur-carbon bonds using the same catalytic system. The result is the first observation of the efficient catalytic oxidative cleavage of phosphorus-carbon and sulfur-carbon bonds under mild conditions, using dioxygen as the oxidant [2]. In addition to the achievements described above, they have unpublished results in several other areas. For example, they have investigated the possibility of using dihydrogen rather than carbon monoxide as a coreductant in the catalytic deep oxidation of substrates. Even more attractive from a practical standpoint is the possibility of using a mixture of carbon monoxide and dihydrogen (synthesis gas). Indeed, experiments indicated that it is possible to substitute carbon monoxide by dihydrogen or synthesis gas. Significantly, in the case of nitro compounds, the deep oxidation in fact proceeded

  5. Complete Oxidation of Propionate, Valerate, Succinate, and Other Organic Compounds by Newly Isolated Types of Marine, Anaerobic, Mesophilic, Gram-Negative, Sulfur-Reducing Eubacteria

    Science.gov (United States)

    Finster, Kai; Bak, Friedhelm

    1993-01-01

    Anaerobic enrichment cultures with either propionate, succinate, lactate, or valerate and elemental sulfur and inocula from shallow marine or deep-sea sediments were dominated by rod-shaped motile bacteria after three transfers. By application of deep-agar dilutions, five eubacterial strains were obtained in pure culture and designated Kyprop, Gyprop, Kysw2, Gylac, and Kyval. All strains were gram negative and grew by complete oxidation of the electron donors and concomitant stoichiometric reduction of elemental sulfur to hydrogen sulfide. The isolates used acetate, propionate, succinate, lactate, pyruvate, oxaloacetate, maleate, glutamate, alanine, aspartate, and yeast extract. All isolates, except strain Gylac, used citrate as an electron donor but valerate was oxidized only by strain Kyval. Fumarate and malate were degraded by all strains without an additional electron donor or acceptor. Kyprop, Gyprop, and Gylac utilized elemental sulfur as the sole inorganic electron acceptor, while Kysw2 and Kyval also utilized nitrate, dimethyl sulfoxide, or Fe(III)-citrate as an electron acceptor. Images PMID:16348934

  6. Modeling and observational constraints on the sulfur cycle in the marine troposphere: a focus on reactive halogens and multiphase chemistry

    Science.gov (United States)

    Chen, Q.; Breider, T.; Schmidt, J.; Sherwen, T.; Evans, M. J.; Xie, Z.; Quinn, P.; Bates, T. S.; Alexander, B.

    2017-12-01

    The radiative forcing from marine boundary layer clouds is still highly uncertain, which partly stems from our poor understanding of cloud condensation nuclei (CCN) formation. The oxidation of dimethyl sulfide (DMS) and subsequent chemical evolution of its products (e.g. DMSO) are key processes in CCN formation, but are generally very simplified in large-scale models. Recent research has pointed out the importance of reactive halogens (e.g. BrO and Cl) and multiphase chemistry in the tropospheric sulfur cycle. In this study, we implement a series of sulfur oxidation mechanisms into the GEOS-Chem global chemical transport model, involving both gas-phase and multiphase oxidation of DMS, DMSO, MSIA and MSA, to improve our understanding of the sulfur cycle in the marine troposphere. DMS observations from six locations around the globe and MSA/nssSO42- ratio observations from two ship cruises covering a wide range of latitudes and longitudes are used to assess the model. Preliminary results reveal the important role of BrO for DMS oxidation at high latitudes (up to 50% over Southern Ocean). Oxidation of DMS by Cl radicals is small in the model (within 10% in the marine troposphere), probably due to an underrepresentation of Cl sources. Multiphase chemistry (e.g. oxidation by OH and O3 in cloud droplets) is not important for DMS oxidation but is critical for DMSO oxidation and MSA production and removal. In our model, about half of the DMSO is oxidized in clouds, leading to the formation of MSIA, which is further oxidized to form MSA. Overall, with the addition of reactive halogens and multiphase chemistry, the model is able to better reproduce observations of seasonal variations of DMS and MSA/nssSO42- ratios.

  7. Steam regenerative removal of hydrogen sulfide from hot syngas by a novel tin oxide and yttrium oxide sorbent

    International Nuclear Information System (INIS)

    Yang, Yi; Shi, Yixiang; Cai, Ningsheng

    2017-01-01

    A novel H 2 S sorbent based on SnO 2 and Y 2 O 3 is developed by a co-precipitation method for steam regenerative removal of H 2 S from hot syngas at moderate temperatures (400–500 °C). SnO 2 -Y 2 O 3 sorbent is stable in a reducing atmosphere (i.e. 500 °C, 50% H 2 ) and achieves a 99.9% H 2 S removal during successive desulfurization and regeneration cycles. The addition of yttrium to SnO 2 decreases the reduction property of SnO 2 and no metallic Sn exists in the reducing atmosphere due to the formation of a pyrochlore-type compound, Y 2 Sn 2 O 7 . The SnO 2 -Y 2 O 3 sorbent has a desulfurization performance deterioration with the increasing calcination temperature. The newly developed SnO 2 -Y 2 O 3 sorbent can be regenerated by steam at 500 °C. In the eight successive desulfurization and regeneration cycles, SnO 2 -Y 2 O 3 sorbent has a cyclic breakthrough sulfur capacity of 9 mg/g without significant sulfur capacity loss. - Highlights: • Reversible warm gas H 2 S clean up. • Suppressing SnO 2 reduction by formation of Sn 2 Y 2 O 7 . • Sn2Y-700 steam regeneration and cycling characterization.

  8. Removal of organic pollutants from industrial wastewater by applying photo-Fenton oxidation technology

    Directory of Open Access Journals (Sweden)

    Ebrahiem E. Ebrahiem

    2017-05-01

    Full Text Available The general strategy of this study was based on evaluation of the possibility of applying advanced photo-oxidation technique (Fenton oxidation process for removal of the residuals organic pollutants present in cosmetic wastewater. The different parameters that affect the chemical oxidation process for dyes in their aqueous solutions were studied by using Fenton’s reaction. These parameters are pH, hydrogen peroxide (H2O2 dose, ferrous sulfate (FeSO4·7H2O dose, Initial dye concentration, and time. The optimum conditions were found to be: pH 3, the dose of 1 ml/l H2O2 and 0.75 g/l for Fe(II and Fe(III and reaction time 40 min. Finally, chemical oxygen demands (COD, before and after oxidation process was measured to ensure the entire destruction of organic dyes during their removal from wastewater. The experimental results show that Fenton’s oxidation process successfully achieved very good removal efficiency over 95%.

  9. Application of chemical oxidation for removal of pharmaceuticals in wastewater effluents

    DEFF Research Database (Denmark)

    Hey, G.; Ledin, A.; la Cour Jansen, J.

    2012-01-01

    treatment dose is comparable to ClO2. Nevertheless, ozonation significantly enhanced the removal of most APIs including carbamazepine, metoprolol, flutamide, bupropion and beclomethasone. In addition, ozonation allows removal of ibuprofen at higher oxidant dose. APIs that possess the reactive electron...

  10. Genome-resolved metagenomics reveals that sulfur metabolism dominates the microbial ecology of rising hydrothermal plumes

    Science.gov (United States)

    Anantharaman, K.; Breier, J. A., Jr.; Jain, S.; Reed, D. C.; Dick, G.

    2015-12-01

    Deep-sea hydrothermal plumes occur when hot fluids from hydrothermal vents replete with chemically reduced elements and compounds like sulfide, methane, hydrogen, ammonia, iron and manganese mix with cold, oxic seawater. Chemosynthetic microbes use these reduced chemicals to power primary production and are pervasive throughout the deep sea, even at sites far removed from hydrothermal vents. Although neutrally-buoyant hydrothermal plumes have been well-studied, rising hydrothermal plumes have received little attention even though they represent an important interface in the deep-sea where microbial metabolism and particle formation processes control the transformation of important elements and impact global biogeochemical cycles. In this study, we used genome-resolved metagenomic analyses and thermodynamic-bioenergetic modeling to study the microbial ecology of rising hydrothermal plumes at five different hydrothermal vents spanning a range of geochemical gradients at the Eastern Lau Spreading Center (ELSC) in the Western Pacific Ocean. Our analyses show that differences in the geochemistry of hydrothermal vents do not manifest in microbial diversity and community composition, both of which display only minor variance across ELSC hydrothermal plumes. Microbial metabolism is dominated by oxidation of reduced sulfur species and supports a diversity of bacteria, archaea and viruses that provide intriguing insights into metabolic plasticity and virus-mediated horizontal gene transfer in the microbial community. The manifestation of sulfur oxidation genes in hydrogen and methane oxidizing organisms hints at metabolic opportunism in deep-sea microbes that would enable them to respond to varying redox conditions in hydrothermal plumes. Finally, we infer that the abundance, diversity and metabolic versatility of microbes associated with sulfur oxidation impart functional redundancy that could allow it to persist in the dynamic settings of hydrothermal plumes.

  11. Transformation and removal of arsenic in groundwater by sequential anodic oxidation and electrocoagulation.

    Science.gov (United States)

    Zhang, Peng; Tong, Man; Yuan, Songhu; Liao, Peng

    2014-08-01

    Oxidation of As(III) to As(V) is generally essential for the efficient remediation of As(III)-contaminated groundwater. The performance and mechanisms of As(III) oxidation by an as-synthesized active anode, SnO2 loaded onto Ti-based TiO2 nanotubes (Ti/TiO2NTs/Sb-SnO2), were investigated. The subsequent removal of total arsenic by electrocoagulation (EC) was further tested. The Ti/TiO2NTs/Sb-SnO2 anode showed a high and lasting electrochemical activity for As(III) oxidation. 6.67μM As(III) in synthetic groundwater was completely oxidized to As(V) within 60min at 50mA. Direct electron transfer was mainly responsible at the current below 30mA, while hydroxyl radicals contributed increasingly with the increase in the current above 30mA. As(III) oxidation was moderately inhibited by the presence of bicarbonate (20mM), while was dramatically increased with increasing the concentration of chloride (0-10mM). After the complete oxidation of As(III) to As(V), total arsenic was efficiently removed by EC in the same reactor by reversing electrode polarity. The removal efficiency increased with increasing the current but decreased by the presence of phosphate and silica. Anodic oxidation represents an effective pretreatment approach to increasing EC removal of As(III) in groundwater under O2-limited conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Comparative study of the oxidation behavior of sulfur-containing amino acids and glutathione by electrochemistry-mass spectrometry in the presence and absence of cisplatin.

    Science.gov (United States)

    Zabel, Robert; Weber, Günther

    2016-02-01

    Small sulfur-containing compounds are involved in several important biochemical processes, including-but not limited to-redox regulation and drug conjugation/detoxification. While methods for stable redox pairs of such compounds (thiols/disulfides) are available, analytical data on more labile and short-lived redox intermediates are scarce, due to highly challenging analytical requirements. In this study, we employ the direct combination of reagentless electrochemical oxidation and mass spectrometric (EC-MS) identification for monitoring oxidation reactions of cysteine, N-acetylcysteine, methionine, and glutathione under simulated physiological conditions (pH 7.4, 37 °C). For the first time, all theoretically expected redox intermediates-with only one exception-are detected simultaneously and in situ, including sulfenic, sulfinic, and sulfonic acids, disulfides, thiosulfinates, thiosulfonates, and sulfoxides. By monitoring the time/potential-dependent interconversion of sulfur species, mechanistic oxidation routes are confirmed and new reactions detected, e.g., sulfenamide formation due to reaction with ammonia from the buffer. Furthermore, our results demonstrate a highly significant impact of cisplatin on the redox reactivity of sulfur species. Namely, the amount of thiol oxidation to sulfonic acid via sulfenic and sulfinic acid intermediates is diminished for glutathione in the presence of cisplatin in favor of the disulfide formation, while for N-acetylcysteine the contrary applies. N-acetylcysteine is the only ligand which displays enhanced oxidation currents upon cisplatin addition, accompanied by increased levels of thiosulfinate and thiosulfonate species. This is traced back to thiol reactivity and highlights the important role of sulfenic acid intermediates, which may function as a switch between different oxidation routes.

  13. Sulfur-doped porous reduced graphene oxide hollow nanosphere frameworks as metal-free electrocatalysts for oxygen reduction reaction and as supercapacitor electrode materials.

    Science.gov (United States)

    Chen, Xi'an; Chen, Xiaohua; Xu, Xin; Yang, Zhi; Liu, Zheng; Zhang, Lijie; Xu, Xiangju; Chen, Ying; Huang, Shaoming

    2014-11-21

    Chemical doping with foreign atoms is an effective approach to significantly enhance the electrochemical performance of the carbon materials. Herein, sulfur-doped three-dimensional (3D) porous reduced graphene oxide (RGO) hollow nanosphere frameworks (S-PGHS) are fabricated by directly annealing graphene oxide (GO)-encapsulated amino-modified SiO2 nanoparticles with dibenzyl disulfide (DBDS), followed by hydrofluoric acid etching. The XPS and Raman spectra confirmed that sulfur atoms were successfully introduced into the PGHS framework via covalent bonds. The as-prepared S-PGHS has been demonstrated to be an efficient metal-free electrocatalyst for oxygen reduction reaction (ORR) with the activity comparable to that of commercial Pt/C (40%) and much better methanol tolerance and durability, and to be a supercapacitor electrode material with a high specific capacitance of 343 F g(-1), good rate capability and excellent cycling stability in aqueous electrolytes. The impressive performance for ORR and supercapacitors is believed to be due to the synergistic effect caused by sulfur-doping enhancing the electrochemical activity and 3D porous hollow nanosphere framework structures facilitating ion diffusion and electronic transfer.

  14. Small Systems Use of a Solid Arsenic Oxidizing Media in Place of Chemical Oxidation to Enhance Arsenic Removal

    Science.gov (United States)

    Presentation provides information on the need to oxidize As III to As V to increase arsenic removal followed by information on the results of an arsenic demonstration project (Plainview CDS) using a solid oxidizing media (Filox) to oxidize As III. The presentation includes a sho...

  15. Partial oxidation of jet fuels over Rh/Al{sub 2}O{sub 3}. Design and reaction kinetics of sulfur-containing surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Baer, Julian Nicolaas

    2016-07-01

    The conversion of logistic fuels via catalytic partial oxidation (CPOX) on Rh/Al{sub 2}O{sub 3} at short contact times is an efficient method for generating hydrogen-rich synthesis gas. Depending on the inlet conditions, fuel, and catalyst, high syngas yields, low by-product formation, and rates of high fuel conversion can be achieved. CPOX is relevant for mobile hydrogen generation, e.g., on board of airplanes in order to increase the fuel efficiency via fuel cell-based auxiliary power units. Jet fuels contain hundreds of different hydrocarbons and a significant amount of sulfur. The hydrocarbon composition and sulfur content of a jet fuel vary depending on distributor, origin, and refinement of the crude oil. Little is known about the influence of the various compounds on the synthesis-gas yield and the impact of sulfur on the product yield. In this work, the influence of three main chemical compounds of a jet fuel (aromatics, alkanes, and sulfur compounds) on syngas selectivity, the catalyst deactivation process, and reaction sequence is unraveled. As representative components of alkanes and aromatics, n-dodecane and 1,2,4-trimethylbenzene were chosen for ex-situ and in-situ investigations on the CPOX over Rh/Al{sub 2}O{sub 3}, respectively. Additionally, for a fixed paraffin-to-aromatics ratio, benzothiophene or dibenzothiophene were added as a sulfur component in three different concentrations. The knowledge gained about the catalytic partial oxidation of jet fuels and their surrogates is used to identify requirements for jet fuels in mobile applications based on CPOX and to optimize the overall system efficiency. The results show an influence of the surrogate composition on syngas selectivity. The tendency for syngas formation increases with higher paraffin contents. A growing tendency for by-product formation can be observed with increasing aromatics contents in the fuel. The impact of sulfur on the reaction system shows an immediate change in the product

  16. Combination of cathodic reduction with adsorption for accelerated removal of Cr(VI) through reticulated vitreous carbon electrodes modified with sulfuric acid–glycine co-doped polyaniline

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Xi [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Yang, Zhao-hui, E-mail: yzh@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Xu, Hai-yin; Zeng, Guang-ming; Huang, Jing; Yang, Xia; Song, Pei-pei; Wang, Li-ke [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

    2015-04-09

    Highlights: • RVC/PANI-SA-GLY electrode was applied as a novel electrode material for accelerated removal of Cr(VI). • Faster reduction kinetics of Cr(VI) was observed by RVC/PANI-SA-GLY electrode when compared with RVC/PANI-SA and RVC electrode. • Cr(VI) removal experienced an adsorption-reduction system built by RVC/PANI-SA-GLY electrode. • The stability of RVC/PANI-SA-GLY electrode was relatively satisfactory. - Abstract: Improving the reduction kinetics is crucial in the electroreduction process of Cr(VI). In this study, we developed a novel adsorption–electroreduction system for accelerated removal of Cr(VI) by employing reticulated vitreous carbon electrode modified with sulfuric acid–glycine co-doped polyaniline (RVC/PANI-SA-GLY). Firstly, response surface methodology confirmed the optimum polymerization condition of co-doped polyaniline for modifying electrodes (Aniline, sulfuric acid and glycine, respectively, of 0.2 mol/L, 0.85 mol/L, 0.93 mol/L) when untraditional dopant glycine was added. Subsequently, RVC/PANI-SA-GLY showed higher Cr(VI) removal percentages in electroreduction experiments over RVC electrode modified with sulfuric acid doped polyaniline (RVC/PANI-SA) and bare RVC electrode. In contrast to RVC/PANI-SA, the improvement by RVC/PANI-SA-GLY was more significant and especially obvious at more negative potential, lower initial Cr(VI) concentration, relatively less acidic solution and higher current densities, best achieving 7.84% higher removal efficiency with entire Cr(VI) eliminated after 900 s. Current efficiencies were likewise enhanced by RVC/PANI-SA-GLY under quite negative potentials. Fourier transform infrared (FTIR) and energy dispersive spectrometer (EDS) analysis revealed a possible adsorption–reduction mechanism of RVC/PANI-SA-GLY, which greatly contributed to the faster reduction kinetics and was probably relative to the absorption between protonated amine groups of glycine and HCrO{sub 4}{sup −}. Eventually, the

  17. Mercury adsorption properties of sulfur-impregnated adsorbents

    Science.gov (United States)

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  18. Removal of dimethyl sulfide by the combination of non-thermal plasma and biological process.

    Science.gov (United States)

    Wei, Z S; Li, H Q; He, J C; Ye, Q H; Huang, Q R; Luo, Y W

    2013-10-01

    A bench scale system integrated with a non-thermal plasma (NTP) and a biotricking filtration (BTF) unit for the treatment of gases containing dimethyl sulfide (DMS) was investigated. DMS removal efficiency in the integrated system was up to 96%. Bacterial communities in the BTF were assessed by PCR-DGGE, which play the dominant role in the biological processes of metabolism, sulfur oxidation, sulfate-reducing and carbon oxidation. The addition of ozone from NTP made microbial community in BTF more complicated and active for DMS removal. The NTP oxidize DMS to simple compounds such as methanol and carbonyl sulfide; the intermediate organic products and DMS are further oxidized to sulfate, carbon dioxide, water vapors by biological degradation. These results show that NTP-BTF is achievable and open new possibilities for applying the integrated with NTP and BTF to odour gas treatment. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Integrated bio-oxidation and adsorptive filtration reactor for removal of arsenic from wastewater.

    Science.gov (United States)

    Kamde, Kalyani; Dahake, Rashmi; Pandey, R A; Bansiwal, Amit

    2018-01-08

    Recently, removal of arsenic from different industrial effluent discharged using simple, efficient and low-cost technique has been widely considered. In this study, removal of arsenic (As) from real wastewater has been studied employing modified bio-oxidation followed by adsorptive filtration method in a novel continuous flow through the reactor. This method includes biological oxidation of ferrous to ferric ions by immobilized Acidothiobacillus ferrooxidans bacteria on granulated activated carbon (GAC) in fixed bed bio-column reactor with the adsorptive filtration unit. Removal efficiency was optimized regarding the initial flow rate of media and ferrous ions concentration. Synthetic wastewater sample having different heavy metal ions such as Arsenic (As), Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb) and Manganese (Mn) were also used in the study. The structural and surface changes occurring after the treatment process were scrutinized using FT-IR and Scanning Electron Microscopy (SEM) analysis. The finding showed that not only arsenic can be removed considerably in the bioreactor system, but also removing efficiency was much more (oxidation with adsorptive filtration method improves the removal efficiency of arsenic and other heavy metal ions in wastewater sample.

  20. Partial genome sequence of Thioalkalivibrio thiocyanodenitrificans ARhD 1T, a chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacterium capable of complete denitrification

    NARCIS (Netherlands)

    Berben, T.; Sorokin, D.Y.; Ivanova, N.; Pati, A.; Kyrpides, N.; Goodwin, L.A; Woyke, T.; Muyzer, G.

    2015-01-01

    Thioalkalivibrio thiocyanodenitrificans strain ARhD 1 T is a motile, Gram-negative bacterium isolated from soda lakes that belongs to the Gammaproteobacteria. It derives energy for growth and carbon fixation from the oxidation of sulfur compounds, most notably thiocyanate, and so is a

  1. Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel

    Science.gov (United States)

    Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

    2017-02-01

    The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

  2. Aqueous arsenite removal by simultaneous ultraviolet photocatalytic oxidation-coagulation of titanium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuxia [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Duan, Jinming, E-mail: jinmingduan@xauat.edu.cn [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia (Australia); Li, Wei [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Beecham, Simon; Mulcahy, Dennis [Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia (Australia)

    2016-02-13

    Highlights: • A simultaneous UV catalysed oxidation–coagulation for As(III) removal is proposed. • As(III) was effectively oxidised to As(V) by the UV catalysed coagulation. • >99% removal for As(III) in pH 4–6 at low doses of Ti(SO{sub 4}){sub 2} was achieved. • Concurrent UV radiation in massive small crystal formation facilitate the effects. • Reaction mechanisms involve both hydroxyl radicals and superoxide radicals. - Abstract: This study explored the efficacy and efficiency of a simultaneous UV-catalyzed oxidation–coagulation process of titanium sulfate (UV/Ti(SO{sub 4}){sub 2}) for efficient removal of As(III) from water. It revealed that, As(III) could be oxidized to As(V) during the UV catalyzed coagulation of Ti(SO{sub 4}){sub 2} with highly efficient As(III) removal in the pH range 4–6{sub .} The UV catalyzed oxidation–coagulation showed surprisingly effective oxidation of As(III) to As(V) within a short time. XPS indicated that 84.7% of arsenic on the coagulated precipitate was in the oxidized form of As(V) after the UV/Ti(SO{sub 4}){sub 2} treatment of As(III) aqueous solutions at pH 5. Arsenic remaining in solution at high pH was in the oxidized form As(V). Removal efficiencies of As(III) were investigated as a function of pH, Ti(SO{sub 4}){sub 2} dosage, initial As(III) concentration and irradiation energy. As(III) could almost completely be removed (>99%) by the photocatalytic oxidation–coagulation process with a moderate dose of Ti(SO{sub 4}){sub 2} in the pH range 4–6 at an initial arsenic concentration of 200 μg/L. The mechanisms of the photocatalytic coagulation oxidation of Ti(SO{sub 4}){sub 2} are similar to those of UV/crystalline TiO{sub 2} particles, involving the formation and reactions of the hydroxyl radical OH· and superoxide HO{sub 2}·/O{sub 2}{sup ·−}.

  3. Means of absorption for dry removal of sulfur dioxide from slack gases. Absorptionsmittel fuer die trockene Entfernung von Schwefedioxid aus Rauchgasen

    Energy Technology Data Exchange (ETDEWEB)

    Gebhard, G; Glaser, W; Hein, K

    1984-03-01

    This is a means of absorption for the dry removal of sulfur dioxide and other harmful substances from the stack gases from boilers. The means of absorption consists mainly of a fine-grained inorganic alkaline earth compound, particularly a calcium and/or a magnesium compound and an additive in the form of one or more carbonic acids and/or of their alkali salts, ammonium salts or alkaline earth salts.

  4. Removal of the antiviral agent oseltamivir and its biological activity by oxidative processes

    International Nuclear Information System (INIS)

    Mestankova, Hana; Schirmer, Kristin; Escher, Beate I.; Gunten, Urs von

    2012-01-01

    The antiviral agent oseltamivir acid (OA, the active metabolite of Tamiflu ® ) may occur at high concentrations in wastewater during pandemic influenza events. To eliminate OA and its antiviral activity from wastewater, ozonation and advanced oxidation processes were investigated. For circumneutral pH, kinetic measurements yielded second-order rate constants of 1.7 ± 0.1 × 10 5 and 4.7 ± 0.2 × 10 9 M −1 s −1 for the reaction of OA with ozone and hydroxyl radical, respectively. During the degradation of OA by both oxidants, the antiviral activity of the treated aqueous solutions was measured by inhibition of neuraminidase activity of two different viral strains. A transient, moderate (two-fold) increase in antiviral activity was observed in solutions treated up to a level of 50% OA transformation, while for higher degrees of transformation the activity corresponded to that caused exclusively by OA. OA was efficiently removed by ozonation in a wastewater treatment plant effluent, suggesting that ozonation can be applied to remove OA from wastewater. - Highlights: ► Oseltamivir acid (OA) is oxidized by ozone and hydroxyl radical. ► Kinetics: We determined rate constants for the reaction with these oxidants. ► The specific activity of OA as neuraminidase inhibitor disappeared during oxidation. ► Ozonation and advanced oxidation can effectively remove OA from wastewaters. - Ozone and hydroxyl radical treatment processes can degrade aqueous oseltamivir acid and remove its antiviral activity.

  5. Isotopic composition of reduced and oxidized sulfur in the Canary Islands: implications for the mantle S cycle

    Science.gov (United States)

    Beaudry, P.; Longpre, M. A.; Wing, B. A.; Bui, T. H.; Stix, J.

    2017-12-01

    The Earth's mantle contains distinct sulfur reservoirs, which can be probed by sulfur isotope analyses of volcanic rocks and gases. We analyzed the isotopic composition of reduced and oxidized sulfur in a diverse range of volcanically derived materials spanning historical volcanism in the Canary Islands. Our sample set consists of subaerial volcanic tephras from three different islands, mantle and sedimentary xenoliths, as well as lava balloon samples from the 2011-2012 submarine El Hierro eruption and associated crystal separates. This large sample set allows us to differentiate between the various processes responsible for sulfur isotope heterogeneity in the Canary archipelago. Our results define an array in triple S isotope space between the compositions of the MORB and seawater sulfate reservoirs. Specifically, the sulfide values are remarkably homogeneous around d34S = -1 ‰ and D33S = -0.01 ‰, while sulfate values peak at d34S = +4 ‰ and D33S = +0.01 ‰. Lava balloons from the El Hierro eruption have highly enriched sulfate d34S values up to +19.3 ‰, reflecting direct interaction between seawater sulfate and the erupting magma. Several sulfate data points from the island of Lanzarote also trend towards more positive d34S up to +13.8 ‰, suggesting interaction with seawater sulfate-enriched lithologies or infiltration of seawater within the magmatic system. On the other hand, the modal values and relative abundances of S2- and S6+ in crystal separates suggest that the Canary Island mantle source has a d34S around +3 ‰, similar to the S-isotopic composition of a peridotite xenolith from Lanzarote. We infer that the S2- and S6+ modes reflect isotopic equilibrium between those species in the magmatic source, which requires 80 % of the sulfide to become oxidized after melting, consistent with measured S speciation. This 34S enrichment of the source could be due to the recycling of hydrothermally-altered oceanic crust, which has been previously suggested

  6. Development of chemically engineered porous metal oxides for phosphate removal

    International Nuclear Information System (INIS)

    Delaney, Paul; McManamon, Colm; Hanrahan, John P.; Copley, Mark P.; Holmes, Justin D.; Morris, Michael A.

    2011-01-01

    In this study, the application of ordered mesoporous silica (OMS) doped with various metal oxides (Zr, Ti, Fe and Al) were studied for the removal of (ortho) phosphate ions from water by adsorption. The materials were characterized by means of N 2 physisorption (BET), powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The doped materials had surface areas between 600 and 700 m 2 g -1 and exhibited pore sizes of 44-64 A. Phosphate adsorption was determined by measurement of the aqueous concentration of orthophosphate using ultraviolet-visible (UV-vis) spectroscopy before and after extraction. The effects of different metal oxide loading ratios, initial concentration of phosphate solution, temperature and pH effects on the efficiency of phosphate removal were investigated. The doped mesoporous materials were effective adsorbents of orthophosphate and up to 100% removal was observed under appropriate conditions. 'Back extracting' the phosphate from the doped silica (following water treatment) was also investigated and shown to have little adverse effect on the adsorbent.

  7. Simultaneous removal of SO2 and NOX with ammonia absorbent in a packed column

    International Nuclear Information System (INIS)

    Jia, Yong; Du, Daqian; Zhang, Xinxi; Ding, Xilou; Zhong, Oin

    2013-01-01

    Catalytic oxidation of NO followed by simultaneous removal of SO 2 and NO X with ammonia is a promising method for control of coal-fired flue gas pollutants. We investigated simultaneous absorption of SO 2 and NO X in a packed column with ammonia, and found that SO 2 and NO X could promote absorption with each other in the process of simultaneous removal SO 2 and NO X . The removal efficiency of SO 2 and NO X was, respectively, about 98% and 70.9% at pH 5.5, temperature 323.15 K, SO 2 concentration 1,800x10 −6 , NO X concentration 400x10 −6 and m NO2 /m NO 1 in our experimental system. The experimental results also show that the formation of sulfite oxidized by reacting with dissolved NO 2 and the molar ratio of sulfite to total sulfur is more than 0.8 in the solution. Accordingly, the energy consumption for sulfite oxidation would be greatly reduced in the process of simultaneous desulfurization and denitrification with ammonia

  8. Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene

    2013-01-01

    Sulfate is the second most abundant anion (behind chloride) in modern seawater, and its cycling is intimately coupled to the cycling of organic matter and oxygen at the Earth’s surface. For example, the reduction of sulfide by microbes oxidizes vast amounts of organic carbon and the subsequent......, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through...... reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth’s history, and our understanding of this history is based mainly...

  9. Micropollutants removal by full-scale UV-C/sulfate radical based Advanced Oxidation Processes.

    Science.gov (United States)

    Rodríguez-Chueca, J; Laski, E; García-Cañibano, C; Martín de Vidales, M J; Encinas, Á; Kuch, B; Marugán, J

    2018-07-15

    The high chemical stability and the low biodegradability of a vast number of micropollutants (MPs) impede their correct treatment in urban wastewater treatment plants. In most cases, the chemical oxidation is the only way to abate them. Advanced Oxidation Processes (AOPs) have been experimentally proved as efficient in the removal of different micropollutants at lab-scale. However, there is not enough information about their application at full-scale. This manuscript reports the application of three different AOPs based on the addition of homogeneous oxidants [hydrogen peroxide, peroxymonosulfate (PMS) and persulfate anions (PS)], in the UV-C tertiary treatment of Estiviel wastewater treatment plant (Toledo, Spain) previously designed and installed in the facility for disinfection. AOPs based on the photolytic decomposition of oxidants have been demonstrated as more efficient than UV-C radiation alone on the removal of 25 different MPs using low dosages (0.05-0.5 mM) and very low UV-C contact time (4-18 s). Photolysis of PMS and H 2 O 2 reached similar average MPs removal in all the range of oxidant dosages, obtaining the highest efficiency with 0.5 mM and 18 s of contact time (48 and 55% respectively). Nevertheless, PMS/UV-C reached slightly higher removal than H 2 O 2 /UV-C at low dosages. So, these treatments are selective to degrade the target compounds, obtaining different removal efficiencies for each compound regarding the oxidizing agent, dosages and UV-C contact time. In all the cases, H 2 O 2 /UV-C is more efficient than PMS/UV-C, comparing the ratio cost:efficiency (€/m 3 ·order). Even H 2 O 2 /UV-C treatments are more efficient than UV-C alone. Thus, the addition of 0.5 mM of H 2 O 2 compensates the increased of UV-C contact time and therefore the increase of electrical consumption, that it should be need to increase the removal of MPs by UV-C treatments alone. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Selective adsorption of refractory sulfur species on active carbons and carbon based CoMo catalyst.

    Science.gov (United States)

    Farag, Hamdy

    2007-03-01

    Adsorption technique could be a reliable alternative in removing to a certain remarkable extent the sulfur species from the feedstock of petroleum oil. The performance of various carbons on adsorption of model sulfur compounds in a simulated feed solution and the sulfur containing compounds in the real gas oil was evaluated. The adsorption experiments have been carried out in a batch scale at ambient temperature and under the atmospheric pressure. In general, the most refractory sulfur compounds in the hydrotreatment reactions were selectively removed and adsorbed. It was found that the adsorbents affinities to dibenzothiophene and 4,6-dimethyldibenzothiophene were much more favored and pronounced than the aromatic matrices like fluorene, 1-methylnaphthalene and 9-methylanthracene. Among the sulfur species, 4,6-dimethyldibenzothiophene was the highest to be removed in terms of both selectivity and capacity over all the present adsorbents. The studied adsorbents showed significant capacities for the polyaromatic thiophenes. The electronic characteristics seem to play a certain role in such behavior. Regeneration of the used adsorbent was successfully attained either by washing it with toluene or by the release of the adsorbates through heat treatment. A suggested adsorptive removal process of sulfur compounds from petroleum distillate over carbon supported CoMo catalyst was discussed.

  11. THE EFFECT OF PH, PHOSPHATE AND OXIDANT TYPE ON THE REMOVAL OF ARSENIC FROM DRINKING WATER DURING IRON REMOVAL

    Science.gov (United States)

    In many regions of the United States, groundwaters that contain arsenic (primarily As[III]) also contain significant amounts of iron (Fe[II]). Arsenic removal will most likely be achieved by iron removal in many of those cases which will consist of oxidization followed by filtra...

  12. Effect of aircraft exhaust sulfur emissions on near field plume aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.C.; Miake-Lye, R.C.; Anderson, M.R.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics

    1997-12-31

    Based on estimated exit plane sulfur speciation, a two dimensional, axisymmetric flow field model with coupled gas phase oxidation kinetics and aerosol nucleation and growth dynamics is used to evaluate the effect of fuel sulfur oxidation in the engine on the formation and growth of volatile H{sub 2}SO{sub 4}/H{sub 2}O aerosols in the near field plume. The conversion of fuel sulfur to sulfur trioxide and sulfuric acid in the engine is predicted to significantly increase the number density and surface area density of volatile H{sub 2}SO{sub 4}/H{sub 2}O aerosols and the chemical activation of exhaust soot particulates. This analysis indicates the need for experimental measurements of exhaust SO{sub x} emissions to fully assess the atmospheric impact of aircraft emissions. (author) 18 refs.; Submitted to Geophysical Research Letters

  13. Effect of aircraft exhaust sulfur emissions on near field plume aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R C; Miake-Lye, R C; Anderson, M R; Kolb, C E [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics

    1998-12-31

    Based on estimated exit plane sulfur speciation, a two dimensional, axisymmetric flow field model with coupled gas phase oxidation kinetics and aerosol nucleation and growth dynamics is used to evaluate the effect of fuel sulfur oxidation in the engine on the formation and growth of volatile H{sub 2}SO{sub 4}/H{sub 2}O aerosols in the near field plume. The conversion of fuel sulfur to sulfur trioxide and sulfuric acid in the engine is predicted to significantly increase the number density and surface area density of volatile H{sub 2}SO{sub 4}/H{sub 2}O aerosols and the chemical activation of exhaust soot particulates. This analysis indicates the need for experimental measurements of exhaust SO{sub x} emissions to fully assess the atmospheric impact of aircraft emissions. (author) 18 refs.; Submitted to Geophysical Research Letters

  14. Removal of organic pollutants from produced water using Fenton oxidation

    Directory of Open Access Journals (Sweden)

    Afzal Talia

    2018-01-01

    Full Text Available Produced water (PW is the largest stream of wastewater from oil and gas exploration. It is highly polluted and requires proper treatment before disposal. The main objective of this study was to investigate the effectiveness of Fenton oxidation in degradation of organic matter in PW. The role of operating factors viz., H2O2 concentration (0.12 × 10-3 moles/L to 3 moles/L, [H2O2]/[Fe2+] molar ratio (2 to 75, and reaction time (30 to 200 minutes, on COD removal was determined through a series of batch experiments conducted in acidic environment at room temperature. The experiments were conducted with 500 mL PW samples in 1L glass beakers covered on the outside with aluminum foil to protect them from sunlight. Pre-decided amounts of ferrous sulfate heptahydrate (FeSO4.7H2O and hydrogen peroxide (H2O2 were added to initiate the Fenton reaction. An increase in COD removal was observed with increase in reaction time and [H2O2]/[Fe2+] molar ratio. COD removal also increased with H2O2 concentration up to 0.01 moles/L; further increase in H2O2 concentration decreased the COD removal efficiency. Over 90% COD removal was achieved under optimum reaction conditions. The study indicates that Fenton oxidation is effective for remediation of PW in terms of organic matter removal.

  15. Removal of organic pollutants from produced water using Fenton oxidation

    Science.gov (United States)

    Afzal, Talia; Hasnain Isa, Mohamed; Mustafa, Muhammad Raza ul

    2018-03-01

    Produced water (PW) is the largest stream of wastewater from oil and gas exploration. It is highly polluted and requires proper treatment before disposal. The main objective of this study was to investigate the effectiveness of Fenton oxidation in degradation of organic matter in PW. The role of operating factors viz., H2O2 concentration (0.12 × 10-3 moles/L to 3 moles/L), [H2O2]/[Fe2+] molar ratio (2 to 75), and reaction time (30 to 200 minutes), on COD removal was determined through a series of batch experiments conducted in acidic environment at room temperature. The experiments were conducted with 500 mL PW samples in 1L glass beakers covered on the outside with aluminum foil to protect them from sunlight. Pre-decided amounts of ferrous sulfate heptahydrate (FeSO4.7H2O) and hydrogen peroxide (H2O2) were added to initiate the Fenton reaction. An increase in COD removal was observed with increase in reaction time and [H2O2]/[Fe2+] molar ratio. COD removal also increased with H2O2 concentration up to 0.01 moles/L; further increase in H2O2 concentration decreased the COD removal efficiency. Over 90% COD removal was achieved under optimum reaction conditions. The study indicates that Fenton oxidation is effective for remediation of PW in terms of organic matter removal.

  16. Actinide removal from molten salts by chemical oxidation and salt distillation

    Energy Technology Data Exchange (ETDEWEB)

    McNeese, J.A.; Garcia, E.; Dole, V.R. [Los Alamos National Laboratory, NM (United States)] [and others

    1995-10-01

    Actinide removal from molten salts can be accomplished by a two step process where the actinide is first oxidized to the oxide using a chemical oxidant such as calcium carbonate or sodium carbonate. After the actinide is precipitated as an oxide the molten salt is distilled away from the actinide oxides leaving a oxide powder heel and an actinide free distilled salt that can be recycled back into the processing stream. This paper discusses the chemistry of the oxidation process and the physical conditions required to accomplish a salt distillation. Possible application of an analogous process sequence for a proposed accelerator driven transmutation molten salt process is also discussed.

  17. Actinide removal from molten salts by chemical oxidation and salt distillation

    International Nuclear Information System (INIS)

    McNeese, James A.; Garcia, Eduardo; Dole, Vonda R.; Griego, Walter J.

    1995-01-01

    Actinide removal from molten salts can be accomplished by a two step process where the actinide is first oxidized to the oxide using a chemical oxidant such as calcium carbonate or sodium carbonate. After the actinide is precipitated as an oxide the molten salt is distilled away from the actinide oxides leaving a oxide powder heel and an actinide free distilled salt that can be recycled back into the processing stream. This paper discusses the chemistry of the oxidation process and the physical conditions required to accomplish a salt distillation. Possible application of an analogous process sequence for a proposed accelerator driven transmutation molten salt process is also discussed

  18. Biological activity of soils strongly polluted with sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Krol, M; Maliszewska, W; Siuta, J

    1972-01-01

    Studies were carried out on soils strongly polluted with sulfur and acidified (to pH 1.4). The soils were subjected to an intensive liming. In field and pot experiments, the authors determined: the total quantity of bacteria, actinomycetes, fungi, azotobacter, nitrifiers, proteolytic activity of microorganisms, activity of ammonifiers and the number of sulfur-oxidizing and sulfate-reducing bacteria. It was found that intensive liming of sulfur-affected soils restored their biological activity. 8 references, 5 figures, 1 table.

  19. Effects of rare-earths additions on the breakdown of protective oxide scales in the presence of sulfur

    International Nuclear Information System (INIS)

    Srinivasan, V.; Goodman, D.E.

    1989-01-01

    Minor additions of rare-earths improve oxide scale adhesion in simple oxidation at high temperatures. The efficacy of such improvements and the role of such additions are not well understood in the presence of sulfur at 500-700 degrees C. Therefore, mixed gas corrosion tests were performed on model Fe-based alloys, with minor additions of rare-earths in an H 2 /H 2 S/H 2 O/Ar gas mixture at 700 degrees C up to 192 hours. The scale breakdown mechanisms were studied on preoxidized samples. The scales and the substrates were characterized by SEM/EDS, and scanning Auger microscopy (AES). The results are discussed

  20. Mercury removal in wastewater by iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Vélez, E; Campillo, G E; Morales, G; Hincapié, C; Osorio, J; Arnache, O; Uribe, J I; Jaramillo, F

    2016-01-01

    Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe 3 O 4 and γ-Fe 2 O 3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λ max ∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements. (paper)

  1. Transport-Induced Spatial Patterns of Sulfur Isotopes (δ34S) as Biosignatures

    Science.gov (United States)

    Mansor, Muammar; Harouaka, Khadouja; Gonzales, Matthew S.; Macalady, Jennifer L.; Fantle, Matthew S.

    2018-01-01

    Cave minerals deposited in the presence of microbes may host geochemical biosignatures that can be utilized to detect subsurface life on Earth, Mars, or other habitable worlds. The sulfur isotopic composition of gypsum (CaSO4·2H2O) formed in the presence of sulfur-oxidizing microbes in the Frasassi cave system, Italy, was evaluated as a biosignature. Sulfur isotopic compositions (δ34SV-CDT) of gypsum sampled from cave rooms with sulfidic air varied from -11 to -24‰, with minor deposits of elemental sulfur having δ34S values between -17 and -19‰. Over centimeter-length scales, the δ34S values of gypsum varied by up to 8.5‰. Complementary laboratory experiments showed negligible fractionation during the oxidation of elemental sulfur to sulfate by Acidithiobacillus thiooxidans isolated from the caves. Additionally, gypsum precipitated in the presence and absence of microbes at acidic pH characteristic of the sulfidic cave walls has δ34S values that are on average 1‰ higher than sulfate. We therefore interpret the 8.5‰ variation in cave gypsum δ34S (toward more negative values) to reflect the isotopic effect of microbial sulfide oxidation directly to sulfate or via elemental sulfur intermediate. This range is similar to that expected by abiotic sulfide oxidation with oxygen, thus complicating the use of sulfur isotopes as a biosignature at centimeter-length scales. However, at the cave room (meter-length) scale, reactive transport modeling suggests that the overall ˜13‰ variability in gypsum δ34S reflects isotopic distillation of circulating H2S gas due to microbial sulfide oxidation occurring along the cave wall-atmosphere interface. Systematic variations of gypsum δ34S along gas flow paths can thus be interpreted as biogenic given that slow, abiotic oxidation cannot produce the same spatial patterns over similar length scales. The expression and preservation potential of this biosignature is dependent on gas flow parameters and diagenetic

  2. Study and modeling of the reduction of sulfur dioxide, nitrogen oxides and hydrogen chloride by dry injection technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wuyin

    1997-05-01

    The potential and mechanism to reduce acid gases, such as sulfur dioxide (SO{sub 2}), nitrogen oxides (NO{sub x}) and hydrogen chloride (HCl), by dry Ca-based sorbents have been studied to improve the efficiency of the process and sorbent utilization. Several natural limestones were tested for SO{sub 2} removal. Calcium conversion as high as 45 % was achieved in the first 0.3 s at 1000 deg C, 1000 ppm SO{sub 2} and Ca/S=1. A SO{sub 2} removal efficiency of 95 % was reached at Ca/S=2. Two models for estimating the sulfation of CaO at high temperature are presented. Short-residence-time sulfation is described by a pore size distribution model and long-residence-time sulfation by a particle expansion model. The pore size distribution model explains the effects of particle size, pore size distribution and partial pressure of SO{sub 2}, suggesting these three factors be the most important for CaO conversion. For particles larger than 1-2 {mu}m in furnace sorbent injection, pore diameters of 50-300 Aa are desirable. When large particles or long residence times are used, as in fluidized bed combustion, the particle expansion model shows the particle size and the sorbent type to be the main factors affecting the reaction. By using the selected limestone and additives the simultaneous SO{sub 2}/NO{sub x} removal was also measured. Several ammonium salts as well as urea were tested. Urea was found to give the highest NO{sub x} removal efficiency. To fully utilize the unreacted Ca-based sorbents, the spent sorbents from SO{sub 2} reduction processes were tested in a fixed-bed reactor to measure the capacity for HCl removal at 150-600 deg C. The results showed that all spent materials could react with HCl to some extent. After being calcined and slaked, they even showed the same reactivity as pure Ca(OH){sub 2}. A shrinking core model was derived for fixed-bed reactor. For the best sorbent tested, the multiple sorbent utilization reached about 80 %. 100 refs, 42 figs, 12 tabs

  3. Sulfur containing nanoporous materials, nanoparticles, methods and applications

    Science.gov (United States)

    Archer, Lynden A.; Navaneedhakrishnan, Jayaprakash

    2018-01-30

    Sulfur containing nanoparticles that may be used within cathode electrodes within lithium ion batteries include in a first instance porous carbon shape materials (i.e., either nanoparticle shapes or "bulk" shapes that are subsequently ground to nanoparticle shapes) that are infused with a sulfur material. A synthetic route to these carbon and sulfur containing nanoparticles may use a template nanoparticle to form a hollow carbon shape shell, and subsequent dissolution of the template nanoparticle prior to infusion of the hollow carbon shape shell with a sulfur material. Sulfur infusion into other porous carbon shapes that are not hollow is also contemplated. A second type of sulfur containing nanoparticle includes a metal oxide material core upon which is located a shell layer that includes a vulcanized polymultiene polymer material and ion conducting polymer material. The foregoing sulfur containing nanoparticle materials provide the electrodes and lithium ion batteries with enhanced performance.

  4. Start-up of simultaneous removal of ammonium and sulfate from an anaerobic ammonium oxidation (anammox) process in an anaerobic up-flow bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhiquan [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China); Zhou Shaoqi, E-mail: fesqzhou@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China); State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, Guangdong 510640 (China); Sun Yanbo [College of Environmental Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510006 (China)

    2009-09-30

    A laboratory testing of simultaneous removal of ammonium and sulfate (SRAS) was studied from an anammox process in an anaerobic bioreactor filled with granular activated carbon. Two different phases of experiment were investigated to start up the SRAS process, and final batch tests were performed to analyze the SRAS process. The experiment included an anammox process and an SRAS process. During the anammox process, the highest removal efficiency of ammonium and nitrite was up to 97 and 98%, respectively. After 160 days in the stationary phase of anammox process, the ratio of ammonium to nitrite consumption was approximately 1:1.15, which is much higher than 1:1.32 in the traditional anammox process. The extra electron acceptor, such as sulfate, was thought to react with ammonium by bacteria. Synthetic wastewater containing ammonium chlorine and sodium sulfate was used as the feed for the bioreactor in the second phase of experiment. During the SRAS process, the influent concentrations of ammonium and sulfate were controlled to be 50-60 and 210-240 mg L{sup -1} respectively. After start-up and acclimatization of this process for 60 days, the average effluent concentrations of ammonium and sulfate were 30 and 160 mg L{sup -1}, respectively. The simultaneous ammonium and sulfate removal was detected in the reactor. In order to further validate the biochemical interaction between ammonium and sulfate, batch tests was carried out. Abiotic tests were carried out to demonstrate that the pure chemical action between ammonium and sulfate without microorganism was not possible. Biotic assays with different ammonium and sulfate concentrations were further investigated that high concentrations of ammonium and sulfate could promote simultaneous removal of ammonium and sulfate. And elemental sulfur and nitrogen gas as the products measured in the SRAS process helped to demonstrate the occurrence of new interaction between nitrogen and sulfur. The new process of SRAS in the

  5. Start-up of simultaneous removal of ammonium and sulfate from an anaerobic ammonium oxidation (anammox) process in an anaerobic up-flow bioreactor

    International Nuclear Information System (INIS)

    Yang Zhiquan; Zhou Shaoqi; Sun Yanbo

    2009-01-01

    A laboratory testing of simultaneous removal of ammonium and sulfate (SRAS) was studied from an anammox process in an anaerobic bioreactor filled with granular activated carbon. Two different phases of experiment were investigated to start up the SRAS process, and final batch tests were performed to analyze the SRAS process. The experiment included an anammox process and an SRAS process. During the anammox process, the highest removal efficiency of ammonium and nitrite was up to 97 and 98%, respectively. After 160 days in the stationary phase of anammox process, the ratio of ammonium to nitrite consumption was approximately 1:1.15, which is much higher than 1:1.32 in the traditional anammox process. The extra electron acceptor, such as sulfate, was thought to react with ammonium by bacteria. Synthetic wastewater containing ammonium chlorine and sodium sulfate was used as the feed for the bioreactor in the second phase of experiment. During the SRAS process, the influent concentrations of ammonium and sulfate were controlled to be 50-60 and 210-240 mg L -1 respectively. After start-up and acclimatization of this process for 60 days, the average effluent concentrations of ammonium and sulfate were 30 and 160 mg L -1 , respectively. The simultaneous ammonium and sulfate removal was detected in the reactor. In order to further validate the biochemical interaction between ammonium and sulfate, batch tests was carried out. Abiotic tests were carried out to demonstrate that the pure chemical action between ammonium and sulfate without microorganism was not possible. Biotic assays with different ammonium and sulfate concentrations were further investigated that high concentrations of ammonium and sulfate could promote simultaneous removal of ammonium and sulfate. And elemental sulfur and nitrogen gas as the products measured in the SRAS process helped to demonstrate the occurrence of new interaction between nitrogen and sulfur. The new process of SRAS in the inorganic

  6. A Cable-Shaped Lithium Sulfur Battery.

    Science.gov (United States)

    Fang, Xin; Weng, Wei; Ren, Jing; Peng, Huisheng

    2016-01-20

    A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new cable-shaped lithium-sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable-shaped lithium-sulfur battery rank far ahead of other fiber-shaped batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Enhancement of Methane Concentration by Removing Contaminants from Biogas Mixtures Using Combined Method of Absorption and Adsorption

    OpenAIRE

    Al Mamun, Muhammad Rashed; Torii, Shuichi

    2017-01-01

    We report a laboratory scale combined absorption and adsorption chemical process to remove contaminants from anaerobically produced biogas using cafeteria (food), vegetable, fruit, and cattle manure wastes. Iron oxide (Fe2O3), zero valent iron (Feo), and iron chloride (FeCl2) react with hydrogen sulfide (H2S) to deposit colloidal sulfur. Silica gel, sodium sulfate (Na2SO4), and calcium oxide (CaO) reduce the water vapour (H2O) and carbon dioxide (CO2). It is possible to upgrade methane (CH4) ...

  8. Estimation of sulfur in coal by fast neutron activation

    International Nuclear Information System (INIS)

    Das, G.C.; Bhattacharyya, P.K.

    1995-01-01

    A simple method is described for estimation of sulfur in coal using fast neutron activation of sulfur, i.e. 32 S(n,p) 32 P and subsequent measurement of 32 P β-activity (1.72 MeV) by a Geiger-Mueller counter. Since the sulfur content of Indian coal ranges from 0.25 to 3%, simulated samples of coal containing sulfur in the range from 0.25 to 3% and common impurities like oxides of aluminium, calcium, iron and silicon have been used to establish the method. (author). 6 refs., 2 figs., 1 tab

  9. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL; SEMIANNUAL

    International Nuclear Information System (INIS)

    Gary M. Blythe

    2002-01-01

    This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2001 through March 31, 2002. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO(sub X) selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, American Electric Power (AEP) and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. This is the fifth reporting period for the subject Cooperative Agreement. During the previous (fourth) period, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Plant. Those tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Plant) and a byproduct magnesium hydroxide slurry (at both Gavin and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70-75% overall sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO(sub 3) formed across the SCR system installed on the unit for NO(sub X) control than at removing SO(sub 3) formed in the furnace. The SO(sub 3) removal results were presented in the

  10. Catalytic oxidative desulfurization of diesel utilizing hydrogen peroxide and functionalized-activated carbon in a biphasic diesel-acetonitrile system

    Energy Technology Data Exchange (ETDEWEB)

    Haw, Kok-Giap; Bakar, Wan Azelee Wan Abu; Ali, Rusmidah; Chong, Jiunn-Fat [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Kadir, Abdul Aziz Abdul [Department of Petroleum Engineering, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2010-09-15

    This paper presents the development of granular functionalized-activated carbon as catalysts in the catalytic oxidative desulfurization (Cat-ODS) of commercial Malaysian diesel using hydrogen peroxide as oxidant. Granular functionalized-activated carbon was prepared from oil palm shell using phosphoric acid activation method and carbonized at 500 C and 700 C for 1 h. The activated carbons were characterized using various analytical techniques to study the chemistry underlying the preparation and calcination treatment. Nitrogen adsorption/desorption isotherms exhibited the characteristic of microporous structure with some contribution of mesopore property. The Fourier Transform Infrared Spectroscopy results showed that higher activation temperature leads to fewer surface functional groups due to thermal decomposition. Micrograph from Field Emission Scanning Electron Microscope showed that activation at 700 C creates orderly and well developed pores. Furthermore, X-ray Diffraction patterns revealed that pyrolysis has converted crystalline cellulose structure of oil palm shell to amorphous carbon structure. The influence of the reaction temperature, the oxidation duration, the solvent, and the oxidant/sulfur molar ratio were examined. The rates of the catalytic oxidative desulfurization reaction were found to increase with the temperature, and H{sub 2}O{sub 2}/S molar ratio. Under the best operating condition for the catalytic oxidative desulfurization: temperature 50 C, atmospheric pressure, 0.5 g activated carbon, 3 mol ratio of hydrogen peroxide to sulfur, 2 mol ratio of acetic acid to sulfur, 3 oxidation cycles with 1 h for each cycle using acetonitrile as extraction solvent, the sulfur content in diesel was reduced from 2189 ppm to 190 ppm with 91.3% of total sulfur removed. (author)

  11. A primer on sulfur for the planetary geologist

    Science.gov (United States)

    Theilig, E.

    1982-01-01

    Sulfur has been proposed as the dominant composition for the volcanic material on Io. Sulfur is a complex element which forms many intramolecular and intermolecular allotropes exhibiting a variety of physical properties. Cyclo-S8 sulfur is the most abundant and stable molecular form. The important molecular species within liquid sulfur change in concentration with temperature. Concentrations of the allotropes control the physical properties of the melt. Discontinuities in density, viscosity, and thermal properties reflect the polymerization process within liquid sulfur. Variations in the melting point are related to autodissociation of the liquid. Many solids forms of sulfur have been identified but only orthorhombic alpha and monoclinic beta sulfur, both composed of cyclo-S8 sulfur, are stable under terrestrial conditions. Physical properties of solid sulfur are dependent on the allotrope and, in some cases, the thermal history. Three natural terrestrial sulfur flows are described: (1) Siretoko-Iosan, Japan; (2) Volcan Azufre, Galapagos Islands; and (3) Mauna Loa, Hawaii. All of the flows are associated with fumarolic areas and are considered to have formed by the melting and mobilization of sulfur deposits. Surface textures of the flows indicate a behavior of molten sulfur similar to that of silicate lava. Channels, rivulets, and lobate edges were described for the flows. The solidification of man-made sulfur flows formed as part of the Frasch mining process by which sulfur is removed from the subsurface in a liquid state is described.

  12. Mathematical Modeling of Nitrous Oxide Production during Denitrifying Phosphorus Removal Process.

    Science.gov (United States)

    Liu, Yiwen; Peng, Lai; Chen, Xueming; Ni, Bing-Jie

    2015-07-21

    A denitrifying phosphorus removal process undergoes frequent alternating anaerobic/anoxic conditions to achieve phosphate release and uptake, during which microbial internal storage polymers (e.g., Polyhydroxyalkanoate (PHA)) could be produced and consumed dynamically. The PHA turnovers play important roles in nitrous oxide (N2O) accumulation during the denitrifying phosphorus removal process. In this work, a mathematical model is developed to describe N2O dynamics and the key role of PHA consumption on N2O accumulation during the denitrifying phosphorus removal process for the first time. In this model, the four-step anoxic storage of polyphosphate and four-step anoxic growth on PHA using nitrate, nitrite, nitric oxide (NO), and N2O consecutively by denitrifying polyphosphate accumulating organisms (DPAOs) are taken into account for describing all potential N2O accumulation steps in the denitrifying phosphorus removal process. The developed model is successfully applied to reproduce experimental data on N2O production obtained from four independent denitrifying phosphorus removal study reports with different experimental conditions. The model satisfactorily describes the N2O accumulation, nitrogen reduction, phosphate release and uptake, and PHA dynamics for all systems, suggesting the validity and applicability of the model. The results indicated a substantial role of PHA consumption in N2O accumulation due to the relatively low N2O reduction rate by using PHA during denitrifying phosphorus removal.

  13. Gene Identification and Substrate Regulation Provide Insights into Sulfur Accumulation during Bioleaching with the Psychrotolerant Acidophile Acidithiobacillus ferrivorans

    Science.gov (United States)

    Liljeqvist, Maria; Rzhepishevska, Olena I.

    2013-01-01

    The psychrotolerant acidophile Acidithiobacillus ferrivorans has been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested that Acidithiobacillus ferrivorans utilized a ferrous iron oxidation pathway similar to that of the related species Acidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since the Acidithiobacillus ferrivorans genome contained genes from both Acidithiobacillus ferrooxidans and Acidithiobacillus caldus encoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that the petA1 and petB1 genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression of cyoB1 (involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate with Acidithiobacillus ferrivorans SS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments. PMID:23183980

  14. Oxidation of Commercial Petronas Diesel with Tert-Butyl Hydroperoxide Over Poly molybdate Alumina Supported Catalyst Modified With Alkaline Earth Metals

    International Nuclear Information System (INIS)

    Wan Nazwanie Wan Abdullah; Rusmidah Ali; Wan Azlee Wan Abu Bakar

    2016-01-01

    Due to strict environmental legislation for ultra-low sulfur diesel fuels, increasing technical and operational challenges are imposed to conventional hydrodesulfurization (HDS) technology. Therefore, catalytic oxidative desulfurization (Cat-ODS) has been suggested to be an alternative method to replace a conventional method which is hydrodesulfurization. In this study, catalytic oxidation of commercial diesel was performed using an oil-soluble oxidant, tert-butyl hydroperoxide (TBHP), over poly molybdate supported on alumina MoO_3-PO_4/ Al_2O_3 catalyst. A commercial Petronas diesel with 440 ppm of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by (GC-FPD). Alkaline earth metals, such as Calcium (Ca), Barium (Ba) and Strontium (Sr) were introduced on the surface of MoO_3-PO_4/ Al_2O_3. The results showed that the catalytic activity decreased in the order, Ca/ MoO_3-PO_4/ Al_2O_3>Sr/ MoO_3-PO_4/ Al_2O_3> Ba/ MoO_3-PO_4/ Al_2O_3. The Ca/ MoO_3-PO_4/ Al_2O_3 catalyst was characterized by XRD and FESEM. XRD results showed that the best catalyst was highly amorphous while FESEM micrograph illustrated an aggregation and agglomeration of various particle sizes. The catalytic activity of Ca/ MoO_3-PO_4/ Al_2O_3 catalyst with various Ca/ Mo ratios were also studied. When the Ca/ Mo ratio was 15:85, the sulfur removal was the highest (79 %) at 45 degree Celsius, 30 min and O/ S molar ratio 3.0 with solvent = dimethylformamide (DMF), diesel/ solvent ratio = 1.0. (author)

  15. Sulfur-oxidizing autotrophic and mixotrophic denitrification processes for drinking water treatment: elimination of excess sulfate production and alkalinity requirement.

    Science.gov (United States)

    Sahinkaya, Erkan; Dursun, Nesrin

    2012-09-01

    This study evaluated the elimination of alkalinity need and excess sulfate generation of sulfur-based autotrophic denitrification process by stimulating simultaneous autotrophic and heterotrophic (mixotrophic) denitrification process in a column bioreactor by methanol supplementation. Also, denitrification performances of sulfur-based autotrophic and mixotrophic processes were compared. In autotrophic process, acidity produced by denitrifying sulfur-oxidizing bacteria was neutralized by the external NaHCO(3) supplementation. After stimulating mixotrophic denitrification process, the alkalinity need of the autotrophic process was satisfied by the alkalinity produced by heterotrophic denitrifiers. Decreasing and lastly eliminating the external alkalinity supplementation did not adversely affect the process performance. Complete denitrification of 75 mg L(-1) NO(3)-N under mixotrophic conditions at 4 h hydraulic retention time was achieved without external alkalinity supplementation and with effluent sulfate concentration lower than the drinking water guideline value of 250 mg L(-1). The denitrification rate of mixotrophic process (0.45 g NO(3)-N L(-1) d(-1)) was higher than that of autotrophic one (0.3 g NO(3)-N L(-1) d(-1)). Batch studies showed that the sulfur-based autotrophic nitrate reduction rate increased with increasing initial nitrate concentration and transient accumulation of nitrite was observed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Removal of FePO4 and Fe3(PO4)2 crystals on the surface of passive fillers in Fe0/GAC reactor using the acclimated bacteria

    International Nuclear Information System (INIS)

    Lai, Bo; Zhou, Yuexi; Yang, Ping; Wang, Juling; Yang, Jinghui; Li, Huiqiang

    2012-01-01

    Highlights: ► Fe 3 (PO 4 ) 2 and FePO 4 crystals would weaken treatment efficiency of Fe 0 /GAC reactor. ► Fe 3 (PO 4 ) 2 and FePO 4 crystals could be removed by the acclimated bacteria. ► FeS and sulfur in the passive film would be removed by the sulfur-oxidizing bacteria. ► Develop a cost-effective bio-regeneration technology for the passive fillers. - Abstract: As past studies presented, there is obvious defect that the fillers in the Fe 0 /GAC reactor begin to be passive after about 60 d continuous running, although the complicated, toxic and refractory ABS resin wastewater can be pretreated efficiently by the Fe 0 /GAC reactor. During the process, the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film are formed by the reaction between PO 4 3− and Fe 2+ /Fe 3+ . Meanwhile, they obstruct the formation of macroscopic galvanic cells between Fe 0 and GAC, which will lower the wastewater treatment efficiency of Fe 0 /GAC reactor. In this study, in order to remove the Fe 3 (PO 4 ) 2 and FePO 4 crystals on the surface of the passive fillers, the bacteria were acclimated in the passive Fe 0 /GAC reactor. According to the results, it can be concluded that the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film could be decomposed or removed by the joint action between the typical propionic acid type fermentation bacteria and sulfate reducing bacteria (SRB), whereas the PO 4 3− ions from the decomposition of the Fe 3 (PO 4 ) 2 and FePO 4 crystals were released into aqueous solution which would be discharged from the passive Fe 0 /GAC reactor. Furthermore, the remained FeS and sulfur (S) in the passive film also can be decomposed or removed easily by the oxidation of the sulfur-oxidizing bacteria. This study provides some theoretical references for the further study of a cost-effective bio-regeneration technology to solve the passive problems of the fillers in the zero-valent iron (ZVI) or Fe 0 /GAC reactor.

  17. The coordination of sulfur in synthetic and biogenic Mg calcites: The red coral case

    Science.gov (United States)

    Perrin, J.; Rivard, C.; Vielzeuf, D.; Laporte, D.; Fonquernie, C.; Ricolleau, A.; Cotte, M.; Floquet, N.

    2017-01-01

    Sulfur has been recognized in biogenic calcites for a long time. However, its structural position is matter of debate. For some authors, sulfur is a marker of the organic matrix while it is part of the calcite structure itself for others. To better understand the place of sulfur in calcite, sulfated magnesian calcites (S-MgCalcite) have been synthetized at high pressure and temperature and studied by μ-XANES spectroscopy. S-MgCalcite XANES spectra show two different types of sulfur: sulfate (SO42-) as a predominant species and a small contribution of sulfite (SO32-), both substituting for carbonate ions in the calcite structure. To address the question of the position of sulfur in biogenic calcites, the oxidation states of sulfur in the skeleton and organic tissues of Corallium rubrum have been investigated by micro X-ray fluorescence (μ-XRF) and sulfur K-edge micro X-ray absorption near edge structure (μ-XANES) spectroscopy at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) on beamline ID21. In the skeleton, sulfur is mainly present as oxidized sulfur SO42- (+VI), plus a weak sulfite contribution. XANES spectra indicate that sulfur is inorganically incorporated as sulfur structurally substituted to carbonate ions (SSS). Although an organic matrix is present in the red coral skeleton, reduced organic sulfur could not be detected by μ-XANES spectroscopy in the skeleton probably due to low organic/inorganic sulfur ratio. In the organic tissues surrounding the skeleton, several sulfur oxidation states have been detected including disulfide (S-S), thioether (R-S-CH3), sulfoxide (SO2), sulfonate (SO2O-) and sulfate (SO42-). The unexpected occurrence of inorganic sulfate within the organic tissues suggests the presence of pre-organized organic/inorganic complexes in the circulatory system of the red coral, precursors to biomineralization ahead of the growth front.

  18. Control and treatment of sulfur oxides emissions; Prevention et traitement des emissions d`oxydes de soufre

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The conference on the control and treatment of sulfur oxides emissions has held in Le Havre the 4. and 5. december, 1997. The aim of this conference was to promote the information on the different treatment technologies and to contribute on the one hand to the supporting and revival of the environmental protection and on the other hand to the desulfurization programs. It has allowed to recall too the technical and financial support of the Ademe to the manufacturers. (O.M.)

  19. Chemiluminescence behavior based on oxidation reaction of rhodamine B with cerium(IV) in sulfuric acid medium

    International Nuclear Information System (INIS)

    Ma Yongjun; Jin Xiaoyong; Zhou Min; Zhang Ziyu; Teng Xiulan; Chen Hui

    2003-01-01

    The chemiluminescence (CL) of the rhodamine B (RhB)-cerium(IV) system was investigated by flow-injection. Rhodamine B was suggested to be a suitable chemiluminescent reagent in acidic conditions. When the concentration of rhodamine B was 100 mg l -1 and cerium sulfate was 1.6 mmol l -1 in sulfuric acid, the chemiluminescent intensity was found to be highest by using 0.3 mol l -1 sulfuric acid as a carrier solution. The particular chemiluminescent system could tolerate such distinct acidic environments that it was utilized for detecting many compounds that are stable in acidic solutions. Furthermore, by virtue of IR, UV-Vis and luminescence spectroscopic measurements, the chemiluminescent behavior of rhodamine B was studied and a possible mechanism for this chemiluminescent reaction was proposed. The emitter was affirmed to be a radical species due to one of the oxidation products of RhB; the chemiluminescent emissive wavelength was about 425 nm

  20. Chemiluminescence behavior based on oxidation reaction of rhodamine B with cerium(IV) in sulfuric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yongjun; Jin Xiaoyong; Zhou Min; Zhang Ziyu; Teng Xiulan; Chen Hui

    2003-08-18

    The chemiluminescence (CL) of the rhodamine B (RhB)-cerium(IV) system was investigated by flow-injection. Rhodamine B was suggested to be a suitable chemiluminescent reagent in acidic conditions. When the concentration of rhodamine B was 100 mg l{sup -1} and cerium sulfate was 1.6 mmol l{sup -1} in sulfuric acid, the chemiluminescent intensity was found to be highest by using 0.3 mol l{sup -1} sulfuric acid as a carrier solution. The particular chemiluminescent system could tolerate such distinct acidic environments that it was utilized for detecting many compounds that are stable in acidic solutions. Furthermore, by virtue of IR, UV-Vis and luminescence spectroscopic measurements, the chemiluminescent behavior of rhodamine B was studied and a possible mechanism for this chemiluminescent reaction was proposed. The emitter was affirmed to be a radical species due to one of the oxidation products of RhB; the chemiluminescent emissive wavelength was about 425 nm.

  1. Preparation of ionic liquid-modified SBA-15 doped with molybdovanadophosphoric acid for oxidative desulfurization

    International Nuclear Information System (INIS)

    Zhuang, Jiang Zhou; Jin, Xiao Yin; Shen, Xian Lin; Tan, Jun Jun; Nie, Long Hui; Xiang, Jian; Hu, Bing

    2015-01-01

    A series of catalysts, ionic liquid-modified SBA-15 (denoted ILSBA) doped with H 5 PMo 10 V 2 O 40 (HPMoV 2 ) have been synthesized and characterized by XRD, FT-IR, 1 H NMR, TG-DTA, and TEM. The catalyst was used for the removal of dibenzothiophene (DBT) in model oil combined with hydrogen peroxide (the oxidant) and acetonitrile (the phase-transfer agent). It was observed that the sulfur content of DBT can be reduced from 500 to 2 ppm by adjusting the amount of catalyst, the reaction temperatures and the reaction time. Besides, the catalyst activity for different sulfur compounds showed a huge difference which may be mainly affected by the electron densities of sulfur atom. Moreover, the catalyst can be recycled seven times without a significant loss in activity, which could be ascribed to the strong electrostatic interaction between ILSBA and HPMoV 2 . In addition, a postulated mechanism was proposed to reveal the oxidative desulfurization process

  2. Regulation characteristics of oxide generation and formaldehyde removal by using volume DBD reactor

    Science.gov (United States)

    Bingyan, CHEN; Xiangxiang, GAO; Ke, CHEN; Changyu, LIU; Qinshu, LI; Wei, SU; Yongfeng, JIANG; Xiang, HE; Changping, ZHU; Juntao, FEI

    2018-02-01

    Discharge plasmas in air can be accompanied by ultraviolet (UV) radiation and electron impact, which can produce large numbers of reactive species such as hydroxyl radical (OH·), oxygen radical (O·), ozone (O3), and nitrogen oxides (NO x ), etc. The composition and dosage of reactive species usually play an important role in the case of volatile organic compounds (VOCs) treatment with the discharge plasmas. In this paper, we propose a volume discharge setup used to purify formaldehyde in air, which is configured by a plate-to-plate dielectric barrier discharge (DBD) channel and excited by an AC high voltage source. The results show that the relative spectral-intensity from DBD cell without formaldehyde is stronger than the case with formaldehyde. The energy efficiency ratios (EERs) of both oxides yield and formaldehyde removal can be regulated by the gas flow velocity in DBD channel, and the most desirable processing effect is the gas flow velocity within the range from 2.50 to 3.33 m s-1. Moreover, the EERs of both the generated dosages of oxides (O3 and NO2) and the amount of removed formaldehyde can also be regulated by both of the applied voltage and power density loaded on the DBD cell. Additionally, the EERs of both oxides generation and formaldehyde removal present as a function of normal distribution with increasing the applied power density, and the peak of the function is appeared in the range from 273.5 to 400.0 W l-1. This work clearly demonstrates the regulation characteristic of both the formaldehyde removal and oxides yield by using volume DBD, and it is helpful in the applications of VOCs removal by using discharge plasma.

  3. Factors affecting radium removal using mixed iron-manganese oxides

    International Nuclear Information System (INIS)

    Mott, H.V. Singh, S.; Kondapally, V.R.

    1993-01-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment

  4. Factors affecting radium removal using mixed iron-manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Mott, H.V. Singh, S.; Kondapally, V.R. (South Dakota School of Mines and Technology, Rapid City, SD (United States))

    1993-10-01

    Batch experiments confirmed that sorption of radium by a mixed iron-manganese oxide solid phase shows promise for treating radium-contaminated water. The capacities of these mixed oxides for sorption of radium depend on the composition of the solid phase, the pH of the aqueous solution, and the presence of competing cations. The removal of the oxide-radium complexes from aqueous suspension by manganese greensand filtration was also investigated. It was found that influent radium concentrations of 100 pCi/L were reduced to 2--9 pCi/L by this process. Additional study of the fate of radium in manganese greensand filters is recommended before this procedure is used for drinking water treatment.

  5. Possibility of use of Azgir underground nuclear cavities for burial of sulfur and her toxic compounds - products of oil refining

    International Nuclear Information System (INIS)

    Akhmetov, E.Z.; Adymov, Zh.I.

    1998-01-01

    is necessary previously to process and to transform into chemically neutral compounds or the sulfur is prepared as granule, covered by an inert, strength and steady shell, for prevention of formation of such harmful compounds, as oxides, chlorides, hydrogen sulphide, sulfuric acid etc. [1]. These neutral compounds and granules should be capable to endure extreme - aggressive physical and chemical conditions and other adverse factors in underground cavities, such as raised temperature, humidity and pressure of gas atmosphere, radio-activity of the alpha-, beta- and gamma-nuclides, products of fission and remains of the non-burned nuclear fuel. The researches of interaction of sulfur with stone salt and constructional materials, ignitability and detonation properties, toxicity, of exude gases and specificity their attack on biological objects, formation of dangerous chemical compounds with the definite substances, influence of intensive radiating emission in cavities on properties of sulfur and also diffuse, migration and transfer of sulfur and sulfur products in stratum of stone salt, the gypsum similar rocks, brine lenses etc. are necessary. The burial of sulfur in underground cavities will give, except direct effect of its removal from eco sphere, real possibility to stabilize cavities and to prevent them convergence and output radionuclides on a day time surface [2], as it happened with similar in Astrakhan area

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

    Directory of Open Access Journals (Sweden)

    Carmen Zaharia

    2014-06-01

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

  7. Three-Dimensionally Hierarchical Graphene Based Aerogel Encapsulated Sulfur as Cathode for Lithium/Sulfur Batteries

    Science.gov (United States)

    Li, Haipeng; Sun, Liancheng; Wang, Zhuo; Zhang, Yongguang; Tan, Taizhe; Wang, Gongkai

    2018-01-01

    A simple and effective method was developed to obtain the electrode for lithium/sulfur (Li/S) batteries with high specific capacity and cycling durability via adopting an interconnected sulfur/activated carbon/graphene (reduced graphene oxide) aerogel (S/AC/GA) cathode architecture. The AC/GA composite with a well-defined interconnected conductive network was prepared by a reduction-induced self-assembly process, which allows for obtaining compact and porous structures. During this process, reduced graphene oxide (RGO) was formed, and due to the presence of oxygen-containing functional groups on its surface, it not only improves the electronic conductivity of the cathode but also effectively inhibits the polysulfides dissolution and shuttle. The introduced activated carbon allowed for lateral and vertical connection between individual graphene sheets, completing the formation of a stable three-dimensionally (3D) interconnected graphene framework. Moreover, a high specific surface area and 3D interconnected porous structure efficiently hosts a higher amount of active sulfur material, about 65 wt %. The designed S/AC/GA composite electrodes deliver an initial capacity of 1159 mAh g−1 at 0.1 C and can retain a capacity of 765 mAh g−1 after 100 cycles in potential range from 1 V to 3 V. PMID:29373525

  8. Three-Dimensionally Hierarchical Graphene Based Aerogel Encapsulated Sulfur as Cathode for Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    Haipeng Li

    2018-01-01

    Full Text Available A simple and effective method was developed to obtain the electrode for lithium/sulfur (Li/S batteries with high specific capacity and cycling durability via adopting an interconnected sulfur/activated carbon/graphene (reduced graphene oxide aerogel (S/AC/GA cathode architecture. The AC/GA composite with a well-defined interconnected conductive network was prepared by a reduction-induced self-assembly process, which allows for obtaining compact and porous structures. During this process, reduced graphene oxide (RGO was formed, and due to the presence of oxygen-containing functional groups on its surface, it not only improves the electronic conductivity of the cathode but also effectively inhibits the polysulfides dissolution and shuttle. The introduced activated carbon allowed for lateral and vertical connection between individual graphene sheets, completing the formation of a stable three-dimensionally (3D interconnected graphene framework. Moreover, a high specific surface area and 3D interconnected porous structure efficiently hosts a higher amount of active sulfur material, about 65 wt %. The designed S/AC/GA composite electrodes deliver an initial capacity of 1159 mAh g−1 at 0.1 C and can retain a capacity of 765 mAh g−1 after 100 cycles in potential range from 1 V to 3 V.

  9. Advanced byproduct recovery: Direct catalytic reduction of sulfur dioxide to elemental sulfur. Quarterly report, April 1--June 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The team of Arthur D. Little, Tufts University and Engelhard Corporation are conducting Phase 1 of a four and a half year, two-phase effort to develop and scale-up an advanced byproduct recovery technology that is a direct, single-stage, catalytic process for converting sulfur dioxide to elemental sulfur. This catalytic process reduces SO{sub 2} over a fluorite-type oxide (such as ceria and zirconia). The catalytic activity can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst as part of an on-going DOE-sponsored, University Coal Research Program. This type of mixed metal oxide catalyst has stable activity, high selectivity for sulfur production, and is resistant to water and carbon dioxide poisoning. Tests with CO and CH{sub 4} reducing gases indicate that the catalyst has the potential for flexibility with regard to the composition of the reducing gas, making it attractive for utility use. The performance of the catalyst is consistently good over a range of SO{sub 2} inlet concentration (0.1 to 10%) indicating its flexibility in treating SO{sub 2} tail gases as well as high concentration streams. The principal objective of the Phase 1 program is to identify and evaluate the performance of a catalyst which is robust and flexible with regard to choice of reducing gas. In order to achieve this goal, the authors have planned a structured program including: Market/process/cost/evaluation; Lab-scale catalyst preparation/optimization studies; Lab-scale, bulk/supported catalyst kinetic studies; Bench-scale catalyst/process studies; and Utility review. Progress is reported from all three organizations.

  10. Desulfurization of organic sulfur from lignite by an electron transfer process

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A. [Selcuk University, Konya (Turkey). Dept. for Chemical Engineering

    2006-10-15

    This study is an attempt to desulfurize organic sulfur from lignite samples with ferrocyanide ion as the electron transferring agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the lignite samples has been investigated. The desulfurization process has been found to be continuous and gradually increases with increase of temperature from 298 to 368 K. The particle size has no significant impact on sulfur removal from the lignite samples. Particle size has no profound impact on the amount of sulfur removal. The desulfurization reaction has been found to be dependent on the concentration of potassium ferrocyanide. Gradual increase in the concentration of potassium ferrocyanide raised the magnitude of desulfurization, but at a higher concentration, the variation is not significant.

  11. Using Demonstrations Involving Combustion and Acid-Base Chemistry to Show Hydration of Carbon Dioxide, Sulfur Dioxide, and Magnesium Oxide and Their Relevance for Environmental Climate Science

    Science.gov (United States)

    Shaw, C. Frank, III; Webb, James W.; Rothenberger, Otis

    2016-01-01

    The nature of acidic and basic (alkaline) oxides can be easily illustrated via a series of three straightforward classroom demonstrations for high school and general chemistry courses. Properties of carbon dioxide, sulfur dioxide, and magnesium oxide are revealed inexpensively and safely. Additionally, the very different kinetics of hydration of…

  12. Adsorptive removal of SO{sub 2} from coal burning by bamboo charcoal

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Zengqiang; Qiu, Jianrong; Xiang, Jun; Zeng, Hancai [Huazhong Univ. of Science and Technology, Wuhan (China). Key Lab. of Coal Combustion

    2013-07-01

    Bamboo charcoal (BC) is an environmentally friendly, low-cost and renewable bioresource with porous structure. The adsorption property of bamboo charcoal for sulfur dioxide was investigated through a parametric study conducted with a bench-scale bed and mechanism study by BET, XPS, and temperature pro-grammed desorption (TPD). The varying parameters investigated include particle size of BC, moisture, oxygen, nitric oxide. The experimental data suggest that BC has a good adsorption potential for SO{sub 2}, which removal efficiency is greatly dependent upon the operation conditions. This study provides a good reference for BC to be used for SO{sub 2} removal in the actual flue gas over a wide range of conditions and further provided the preliminary experimental studies and theoretical discussion for bamboo charcoal to be used in multiple pollutants removing.

  13. Insights into the iron and sulfur energetic metabolism of Acidithiobacillus ferrooxidans by microarray transcriptome profiling

    Energy Technology Data Exchange (ETDEWEB)

    R. Quatrini; C. Appia-Ayme; Y. Denis; J. Ratouchniak; F. Veloso; J. Valdes; C. Lefimil; S. Silver; F. Roberto; O. Orellana; F. Denizot; E. Jedlicki; D. Holmes; V. Bonnefoy

    2006-09-01

    Acidithiobacillus ferrooxidans is a well known acidophilic, chemolithoautotrophic, Gram negative, bacterium involved in bioleaching and acid mine drainage. In aerobic conditions, it gains energy mainly from the oxidation of ferrous iron and/or reduced sulfur compounds present in ores. After initial oxidation of the substrate, electrons from ferrous iron or sulfur enter respiratory chains and are transported through several redox proteins to oxygen. However, the oxidation of ferrous iron and reduced sulfur compounds has also to provide electrons for the reduction of NAD(P) that is subsequently required for many metabolic processes including CO2 fixation. To help to unravel the enzymatic pathways and the electron transfer chains involved in these processes, a genome-wide microarray transcript profiling analysis was carried out. Oligonucleotides corresponding to approximately 3000 genes of the A. ferrooxidans type strain ATCC23270 were spotted onto glass-slides and hybridized with cDNA retrotranscribed from RNA extracted from ferrous iron and sulfur grown cells. The genes which are preferentially transcribed in ferrous iron conditions and those preferentially transcribed in sulfur conditions were analyzed. The expression of a substantial number of these genes has been validated by real-time PCR, Northern blot hybridization and/or immunodetection analysis. Our results support and extend certain models of iron and sulfur oxidation and highlight previous observations regarding the possible presence of alternate electron pathways. Our findings also suggest ways in which iron and sulfur oxidation may be co-ordinately regulated. An accompanying paper (Appia-Ayme et al.) describes results pertaining to other metabolic functions.

  14. New method for reduction of burning sulfur of coal

    International Nuclear Information System (INIS)

    Lyutskanov, L.; Dushanov, D.

    1998-01-01

    The coal pyrolysis is key phase in the the pyrolysis-combustion cycle as it provides char for combustor. The behaviour of sulfur compounds during coal pyrolysis depends on factors as rank of coal, quantity of sulfur and sulfur forms distribution in the coal, quantity and kind of mineral matter and the process conditions. The mineral content of coal may inhibit or catalyze the formation of volatile sulfur compounds. The pyrolysis itself is a mean of removing inorganic and organic sulfur but anyway a portion of it remains in the char while the other moves into the tar and gas. The aim of this study was to determine an optimal reduction of burning sulfur at the coal pyrolysis by varying parametric conditions. The pyrolysis of different kinds of coal has been studied. The samples with size particles o C at atmospheric pressure and with a heating rate of 6-50 o C min -1 . They were treated with exhaust gas and nitrogen at an addition of steam and air. The char obtained remains up to 10 min at the final temperature. The char samples cool without a contact with air. Two methods of desulfurization-pyrolysis were studied - using 9-vertical tubular reactor and 9-horizontal turning reactor. The results obtained show that at all samples there is a decrease of burning sulfur with maximal removal efficiency 83%. For example at a pyrolysis of Maritsa Iztok lignite coal the burning sulfur is only 16% in comparison with the control sample. The remained is 90% sulfate, 10% organic and pyrite traces when a mixture 'exhaust gas-water stream-air' was used. The method of desulfurization by pyrolysis could be applied at different kinds of coal and different conditions. Char obtained as a clean product can be used for generating electric power. This innovation is in a stage of patenting

  15. Chemical trapping and characterization of small oxoacids of sulfur (SOS) generated in aqueous oxidations of H2S.

    Science.gov (United States)

    Kumar, Murugaeson R; Farmer, Patrick J

    2018-04-01

    Small oxoacids of sulfur (SOS) are elusive molecules like sulfenic acid, HSOH, and sulfinic acid, HS(O)OH, generated during the oxidation of hydrogen sulfide, H 2 S, in aqueous solution. Unlike their alkyl homologs, there is a little data on their generation and speciation during H 2 S oxidation. These SOS may exhibit both nucleophilic and electrophilic reactivity, which we attribute to interconversion between S(II) and S(IV) tautomers. We find that SOS may be trapped in situ by derivatization with nucleophilic and electrophilic trapping agents and then characterized by high resolution LC MS. In this report, we compare SOS formation from H 2 S oxidation by a variety of biologically relevant oxidants. These SOS appear relatively long lived in aqueous solution, and thus may be involved in the observed physiological effects of H 2 S. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  16. A statistical approach to the experimental design of the sulfuric acid leaching of gold-copper ore

    Directory of Open Access Journals (Sweden)

    Mendes F.D.

    2003-01-01

    Full Text Available The high grade of copper in the Igarapé Bahia (Brazil gold-copper ore prevents the direct application of the classic cyanidation process. Copper oxides and sulfides react with cyanides in solution, causing a high consumption of leach reagent and thereby raising processing costs and decreasing recovery of gold. Studies have showm that a feasible route for this ore would be a pretreatment for copper minerals removal prior to the cyanidation stage. The goal of this experimental work was to study the experimental conditions required for copper removal from Igarapé Bahia gold-copper ore by sulfuric acid leaching by applying a statistical approach to the experimental design. By using the Plackett Burman method, it was possible to select the variables that had the largest influence on the percentage of copper extracted at the sulfuric acid leaching stage. These were temperature of leach solution, stirring speed, concentration of sulfuric acid in the leach solution and particle size of the ore. The influence of the individual effects of these variables and their interactions on the experimental response were analyzed by applying the replicated full factorial design method. Finally, the selected variables were optimized by the ascending path statistical method, which determined the best experimental conditions for leaching to achieve the highest percentage of copper extracted. Using the optimized conditions, the best leaching results showed a copper extraction of 75.5%.

  17. Removal of emerging pollutants by Ru/TiO2-catalyzed permanganate oxidation.

    Science.gov (United States)

    Zhang, Jing; Sun, Bo; Xiong, Xinmei; Gao, Naiyun; Song, Weihua; Du, Erdeng; Guan, Xiaohong; Zhou, Gongming

    2014-10-15

    TiO2 supported ruthenium nanoparticles, Ru/TiO2 (0.94‰ as Ru), was synthesized to catalyze permanganate oxidation for degrading emerging pollutants (EPs) with diverse organic moieties. The presence of 1.0 g L(-1) Ru/TiO2 increased the second order reaction rate constants of bisphenol A, diclofenac, acetaminophen, sulfamethoxazole, benzotriazole, carbamazepine, butylparaben, diclofenac, ciprofloxacin and aniline at mg L(-1) level (5.0 μM) by permanganate oxidation at pH 7.0 by 0.3-119 times. The second order reaction rate constants of EPs with permanganate or Ru/TiO2-catalyzed permanganate oxidation obtained at EPs concentration of mg L(-1) level (5.0 μM) underestimated those obtained at EPs concentration of μg L(-1) level (0.050 μM). Ru/TiO2-catalyzed permanganate could decompose a mixture of nine EPs at μg L(-1) level efficiently and the second order rate constant for each EP was not decreased due to the competition of other EPs. The toxicity tests revealed that Ru/TiO2-catalyzed permanganate oxidation was effective not only for elimination of EPs but also for detoxification. The removal rates of sulfamethoxazole by Ru/TiO2-catalyzed permanganate oxidation in ten successive cycles remained almost constant in ultrapure water and slightly decreased in Songhua river water since the sixth run, indicating the satisfactory stability of Ru/TiO2. Ru/TiO2-catalyzed permanganate oxidation was selective and could remove selected EPs spiked in real waters more efficiently than chlorination. Therefore, Ru/TiO2-catalyzed permanganate oxidation is promising for removing EPs with electron-rich moieties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Extraction of sulfuric acid with TOPO

    International Nuclear Information System (INIS)

    Shuyun, Xue; Yonghui, Yang; Yanzhao, Yang; Sixiu, Sun; Borong, Bao

    1998-01-01

    A study on solvent extraction of sulfuric acid by tri-octylphosphine oxide (TOPO) in n-heptane has been made. Extraction coefficients of H 2 SO 4 as a function of H 2 SO 4 concentration in aqueous phase, and extractant concentrations in organic phase have been studied. The composition of extracted species, equilibrium constants of extraction reaction have been evaluated. These results are important for interpreting extraction equilibrium data of uranium(VI) or other metal ions with TOPO in sulfuric acid media. (author)

  19. Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    König, C.F.J.; Nachtegaal, M.; Seemann, M.; Clemens, F.; Garderen, N. van; Biollaz, S.M.A.; Schildhauer, T.J.

    2014-01-01

    Highlights: • Mn sorbents remove H 2 S from hot syngas in chemical looping desulfurization process. • State of Mn followed by in situ X-ray absorption spectroscopy and mass spectrometry. • Two-step mechanism explains the formation of SO 2 under reducing conditions. - Abstract: Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature “chemical looping desulfurization” process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO 2 . Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a “chemical looping desulfurization” reactor. The “fuel reactor” gas contained H 2 , CO, CH 4 and H 2 S, similar as in the producer gas, and the “oxidizing reactor” contained diluted O 2 . Mass spectrometry showed that most of the H 2 S is taken up by the sample in the “fuel reactor” part, while also some unwanted SO 2 is generated in the “fuel reactor” part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn 3 O 4 is transformed in the presence of H 2 S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn 3 O 4 oxidizes some H 2 S to the undesired SO 2 in the fuel reactor. Upon exposure to O 2 , MnS is again oxidized to Mn 3 O 4 via MnO, releasing SO

  20. Optimized Ultrasound-Assisted Oxidative Desulfurization Process of Simulated Fuels over Activated Carbon-Supported Phosphotungstic Acid

    Directory of Open Access Journals (Sweden)

    Peniel Jean Gildo

    2018-01-01

    Full Text Available Recent technological advancements respond to the call to minimize/eliminate emissions to the atmosphere. However, on the average, fuel oils which is one of the major raw materials, is found to increase in sulfur concentration due to a phenomenon called thermal maturation. As such, a deeper desulfurization process is needed to obtain low/ultra-low sulfur fuel oils. In the present study, the ultrasound assisted oxidative desulfurization (UAOD processes using the H2O2 and HPW-AC oxidizing system applied to simulated fuel (~2800 ppm sulfur in the form of dibenzothiophene, benzothiophene, and thiophene dissolved in toluene, were optimized. After the pre-saturation of the HPW-AC with the simulated fuel, H2O2 was added just before the reaction was commenced under ultrasonic irradiation. After the application of both 2k-factorial design of experiment for screening and Face-Centered Design of Experiment for optimization, it was found that 25.52 wt% of H2O2 concentration, 983.9 mg of catalyst dose, 9.52 mL aqueous phase per 10 mL of the organic phase and 76.36 minutes of ultrasonication time would render 94.74% oxidation of the sulfur compounds in the simulated fuel. After the application of the optimized parameters to kerosene and employing a 4-cycle extraction using acetonitrile, 99% of the original sulfur content were removed from the kerosene using the UAOD optimized parameters. The desulfurization process resulted in a low-sulfur kerosene which retained its basic fuel properties such as density, viscosity and calorific value.

  1. Advanced sulfur control concepts for hot gas desulfurization technology

    International Nuclear Information System (INIS)

    1998-01-01

    The objective of this project is to develop a hot-gas desulfurization process scheme for control of H 2 S in HTHP coal gas that can be more simply and economically integrated with known regenerable sorbents in DOE/METC-sponsored work than current leading hot-gas desulfurization technologies. In addition to being more economical, the process scheme to be developed must yield an elemental sulfur byproduct. The Direct Sulfur Recovery Process (DSRP), a leading process for producing an elemental sulfur byproduct in hot-gas desulfurization systems, incurs a coal gas use penalty, because coal gas is required to reduce the SO 2 in regeneration off-gas to elemental sulfur. Alternative regeneration schemes, which avoid coal gas use and produce elemental sulfur, will be evaluated. These include (i) regeneration of sulfided sorbent using SO 2 ; (ii) partial oxidation of sulfided sorbent in an O 2 starved environment; and (iii) regeneration of sulfided sorbent using steam to produce H 2 S followed by direct oxidation of H 2 S to elemental sulfur. Known regenerable sorbents will be modified to improve the feasibility of the above alternative regeneration approaches. Performance characteristics of the modified sorbents and processes will be obtained through lab- and bench-scale testing. Technical and economic evaluation of the most promising processes concept(s) will be carried out

  2. Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems.

    Science.gov (United States)

    Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

    2011-12-01

    Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO₂⁻) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N₂O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O₂) is associated with N₂O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N₂O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N₂O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N₂O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N₂O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

  3. Nitrogen-doped graphene nanosheets/sulfur composite as lithium–sulfur batteries cathode

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yong [Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler Street, Miami, FL 33174 (United States); Li, Xifei; Sun, Xueliang [Nanomaterials and Energy Lab, Department of Mechanical and Materials Engineering, Western University, London, Ontario N6A 5B9 (Canada); Energy and Materials Engineering Centre, College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Wang, Chunlei, E-mail: wangc@fiu.edu [Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler Street, Miami, FL 33174 (United States)

    2016-11-15

    Highlights: • NGNSs are synthesized with amino-N and pyridine-N-oxide groups. • NGNSs provide a matrix with high surface area and conductivity. • N groups facilitate immobilization of polysulfides for Li–S batteries. - Abstract: Lithium–sulfur batteries have been receiving unprecedented attentions in recent years due to their exceptional high theoretical capacity and energy density, low cost and environmental friendliness. Yet their practical applications are still hindered by short cycle life, low efficiency and poor conductivity which are mainly caused by the insulating nature of sulfur and dissolution of polysulfides. Here, a nitrogen-doped graphene nanosheets/sulfur (NGNSs/S) composite was synthesized via a facile chemical reaction deposition. In this composite, NGNSs was employed as a conductive host to entrap S/polysulfides in the cathode part. The NGNSs/S composite delivered an initial discharge capacity of 856.7 mAh g{sup −1} and a reversible capacity of 319.3 mAh g{sup −1} at 0.1 C with good recoverable rate capability.

  4. A kinetic and mechanistic study on the oxidation of l-methionine and N-acetyl l-methionine by cerium(IV) in sulfuric acid medium

    OpenAIRE

    T. Sumathi; P. Shanmugasundaram; G. Chandramohan

    2016-01-01

    The kinetics of oxidation of l-methionine and N-acetyl l-methionine by Ce(IV) in sulfuric acid–sulfate media in the range of 288.1–298.1 K has been investigated. The major oxidation products of methionine and N-acetyl l-methionine have been identified as methionine sulfoxide and N-acetyl methionine sulfoxide. The major oxidation products have been confirmed by qualitative analysis and boiling point. The reaction was first order with respect to l-methionine, N-acetyl l-methionine and Ce(IV). I...

  5. Electrochemical reduction of sulfur dioxide in sulfolane

    Energy Technology Data Exchange (ETDEWEB)

    Vorob' ev, A.S.; Gavrilova, A.A.; Kolosnitsyn, V.S.; Nikitin, Yu.E.

    1985-09-01

    Solutions of sulfur dioxide in aproptic media are promising electrolyte oxidizing agents for chemical current sources with anodes of active metals. This work describes the electrochemical reduction of sulfur dioxide in sulfolane in a lithium halide supporting electrolyte which was investigated by the methods of voltamperometry and chronopotentiometry. The dependence of the current of the cathodic peak on the concentration of the supporting electrolyte salts, sulfur dioxide and water, was studied. On the basis of the data obtained, a hypothesis was advanced on the nature of the limiting step. The investigation showed that at low polarizing current densities, a substantial influence on the reduction of sulfur dioxide in sulfolane in a lithium halide supporting electrolyte is exerted by blockage of the electrode surface by sparingly soluble reaction products.

  6. Two-step rapid sulfur capture. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-04-01

    The primary goal of this program was to test the technical and economic feasibility of a novel dry sorbent injection process called the Two-Step Rapid Sulfur Capture process for several advanced coal utilization systems. The Two-Step Rapid Sulfur Capture process consists of limestone activation in a high temperature auxiliary burner for short times followed by sorbent quenching in a lower temperature sulfur containing coal combustion gas. The Two-Step Rapid Sulfur Capture process is based on the Non-Equilibrium Sulfur Capture process developed by the Energy Technology Office of Textron Defense Systems (ETO/TDS). Based on the Non-Equilibrium Sulfur Capture studies the range of conditions for optimum sorbent activation were thought to be: activation temperature > 2,200 K for activation times in the range of 10--30 ms. Therefore, the aim of the Two-Step process is to create a very active sorbent (under conditions similar to the bomb reactor) and complete the sulfur reaction under thermodynamically favorable conditions. A flow facility was designed and assembled to simulate the temperature, time, stoichiometry, and sulfur gas concentration prevalent in the advanced coal utilization systems such as gasifiers, fluidized bed combustors, mixed-metal oxide desulfurization systems, diesel engines, and gas turbines.

  7. Novel KMnO4-modified iron oxide for effective arsenite removal

    International Nuclear Information System (INIS)

    Huang, Yao-Hui; Shih, Yu-Jen; Cheng, Fu-Ji

    2011-01-01

    Highlights: ► We employ the MnBT-4 adsorbent for As (III)/(V) removal in solution. ► The waste iron oxide BT-4 acts as the support to immobilize Mn using FBR reactor. ► MnBT-4 has higher arsenite adsorption as compared with BT4. ► Easy solid–liquid separation and cost effective are the merits of applying MnBT-4. - Abstract: This work demonstrates the synthesis of a novel KMnO 4 -modified form of iron oxide, MnBT-4, using a fluidized bed reactor (FBR) for the adsorptive removal of arsenic (III)/(V). Characterization by XRD, BET, and SEM indicated that the BT-4 support was poorly crystallized goethite (α-FeOOH) with a specific surface area of 229 m 2 g −1 . In FBR experiments of synthesizing MnBT-4, the Fe and Mn salts were found to have an optimal dosage ratio of less than 4, which maximized the KMnO 4 immobilization efficiency. The immobilized Mn compounds on MnBT-4 underwent an additional oxidation step of As (III), promoting arsenic adsorption. When applied MnBT-4 for As (III) removal from solution, the sorption isotherm was accurately fitted with Langmuir and Freundlich models, while the maximum adsorption capacity of 27.4 mg g −1 exceeded those of other adsorbents in the literature. Batch experimental results revealed that both raw BT-4 and MnBT-4 could take up a large amount of As (V). However, the MnBT-4 provided a substantially higher As (III) removal efficiency than BT-4.

  8. Sulfur oxides and nitrogen oxides gas treating process

    International Nuclear Information System (INIS)

    Forbes, J. T.

    1985-01-01

    A process is disclosed for treating particle-containing gas streams by removing particles and gaseous atmospheric pollutants. Parallel passage contactors are utilized to remove the gaseous pollutants. The minimum required gas flow rate for effective operation of these contactors is maintained by recycling a variable amount of low temperature gas which has been passed through a particle removal zone. The recycled gas is reheated by heat exchange against a portion of the treated gas

  9. Fuel removal from plasma-facing components by oxidation-based techniques. An overview of surface conditions after oxidation

    International Nuclear Information System (INIS)

    Rubel, M.J.; De Temmerman, G.; Sergienko, G.; Sundelin, P.; Emmoth, B.; Philipps, V.

    2007-01-01

    Oxygen-assisted fuel removal is reported for laboratory-prepared a-C:D films and for layers obtained by boronisation in a tokamak and then exposed to a helium-oxygen glow discharge in TEXTOR. Oxidation of thick mixed-material co-deposits under laboratory conditions is also presented. The essential results are following: (i) laboratory-prepared amorphous deuterated carbon (a-C:D) layers are decomposed efficiently by the He-O 2 glow: D and C contents are decreased by a factor of 45-220 and 25-60, respectively; (ii) the same treatment of the boronised films leads to the release of D but no removal of carbon is observed; (iii) the thermal oxidation (at 300 deg. C in air under laboratory conditions) of co-deposits on PFC and probes exposed to the SOL reduces the D content by a factor of 4-5 after 2 h, whereas nearly complete fuel removal (98%) occurs after 10 h at 300 deg. C. The study shows that the fuel removal efficiency is dependent on the overall composition of the mixed layer. It is high from pure a-C:D films but distinctly less efficient from real co-deposits

  10. New treating processes for sulfur-containing natural gases

    Energy Technology Data Exchange (ETDEWEB)

    Kislenko, N.; Aphanasiev, A.; Nabokov, S.; Ismailova, H. [VNIIGAS, Moscow (Russian Federation)

    1996-12-31

    The traditional method of removing H{sub 2}S from sour natural gases is first to treat the gas with a solvent and then to recover the H{sub 2}S from the sour stream in a Claus plant. This method recovers up to 97% of the sulfur when a three-stage Claus unit is employed. Amine/Claus units have operating difficulties for small sulfur capacities (up to 5 tons/day) because the operation of the fired equipment (reaction furnace) is much more difficult. Therefore, for small scale sulfur recovery plants redox processes which exhibit a significant reduction in investment and operating costs are normally used. Many different factors influence the choice of gas desulfurization technology--composition and gas flow, environmental sulfur recovery requirements and CO{sub 2}/H{sub 2}S ratio.

  11. Color, TOC and AOX removals from pulp mill effluent by advanced oxidation processes: A comparative study

    International Nuclear Information System (INIS)

    Catalkaya, Ebru Cokay; Kargi, Fikret

    2007-01-01

    Pulp mill effluent containing toxic chemicals was treated by different advanced oxidation processes (AOPs) consisting of treatments by hydrogen peroxide, Fenton's reagent (H 2 O 2 /Fe 2+ ), UV, UV/H 2 O 2 , photo-Fenton (UV/H 2 O 2 /Fe 2+ ), ozonation and peroxone (ozone/H 2 O 2 ) in laboratory-scale reactors for color, total organic carbon (TOC) and adsorbable organic halogens (AOX) removals from the pulp mill effluent. Effects of some operating parameters such as the initial pH, oxidant and catalyst concentrations on TOC, color, AOX removals were investigated. Almost every method used resulted in some degree of color removal from the pulp mill effluent. However, the Fenton's reagent utilizing H 2 O 2 /Fe 2+ resulted in the highest color, TOC and AOX removals under acidic conditions when compared with the other AOPs tested. Approximately, 88% TOC, 85% color and 89% AOX removals were obtained by the Fenton's reagent at pH 5 within 30 min. Photo-Fenton process yielded comparable TOC (85%), color (82%) and AOX (93%) removals within 5 min due to oxidations by UV light in addition to the Fenton's reagent. Fast oxidation reactions by the photo-Fenton treatment makes this approach more favorable as compared to the others used

  12. Sulfur Poisoning of Ni/stabilized-zirconia Anodes – Effect on Long-Term Durability

    DEFF Research Database (Denmark)

    Hauch, Anne; Hagen, Anke; Hjelm, Johan

    2013-01-01

    Sulfur impurities in carbon containing fuels for solid oxide fuel cells (SOFC), e.g. natural gas and biogas, can lead to significant losses in performance due to the sulfur sensitivity of Ni/YSZ SOFC anodes. Full cells having Ni/YSZ and Ni/ScYSZ anodes have been characterized during long-term gal...... to focus on the long-term effect over a few hundred of hours. This work describes and correlates the observed evolution of anode performance, over hundreds of hours, with sulfur poisoning with the different operating conditions.......Sulfur impurities in carbon containing fuels for solid oxide fuel cells (SOFC), e.g. natural gas and biogas, can lead to significant losses in performance due to the sulfur sensitivity of Ni/YSZ SOFC anodes. Full cells having Ni/YSZ and Ni/ScYSZ anodes have been characterized during long...

  13. Gas-phase advanced oxidation as an integrated air pollution control technique

    Directory of Open Access Journals (Sweden)

    Getachew A. Adnew

    2016-03-01

    Full Text Available Gas-phase advanced oxidation (GPAO is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8 and reduced sulfur compounds (e.g. H2S and CH3SH, removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

  14. Graphene oxide/ferric hydroxide composites for efficient arsenate removal from drinking water

    International Nuclear Information System (INIS)

    Zhang Kai; Dwivedi, Vineet; Chi Chunyan; Wu Jishan

    2010-01-01

    A series of novel composites based on graphene oxide (GO) cross-linked with ferric hydroxide was developed for effective removal of arsenate from contaminated drinking water. GO, which was used as a supporting matrix here, was firstly treated with ferrous sulfate. Then, the ferrous compound cross-linked with GO was in situ oxidized to ferric compound by hydrogen peroxide, followed by treating with ammonium hydroxide. The morphology and composition of the composites were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The ferric hydroxide was found to be homogenously impregnated onto GO sheets in amorphous form. These composites were evaluated as absorbents for arsenate removal from contaminated drinking water. For the water with arsenate concentration at 51.14 ppm, more than 95% of arsenate was absorbed by composite GO-Fe-5 with an absorption capacity of 23.78 mg arsenate/g of composite. Effective arsenate removal occurred in a wide range of pH from 4 to 9. However, the efficiency of arsenate removal was decreased when pH was increased to higher than 8.

  15. Process and device for liquid organic waste processing by sulfuric mineralization

    International Nuclear Information System (INIS)

    Aspart, A.; Gillet, B.; Lours, S.; Guillaume, B.

    1990-01-01

    In a chemical reactor containing sulfuric acid are introduced the liquid waste and nitric acid at a controlled flow rate for carbonization of the waste and oxidation of carbon on sulfur dioxide, formed during carbonization, regenerating simultaneously sulfuric acid. Optical density of the liquid is monitored to stop liquid waste feeding above a set-point. The liquid waste can be an organic solvent such as TBP [fr

  16. Io's theothermal (sulfur) - Lithosphere cycle inferred from sulfur solubility modeling of Pele's magma supply

    Science.gov (United States)

    Battaglia, Steven M.; Stewart, Michael A.; Kieffer, Susan W.

    2014-06-01

    Surface deposits of volatile compounds such as water (Earth) or sulfur (Io) on volcanically active bodies suggest that a magmatic distillation process works to concentrate volatiles in surface reservoirs. On Earth, this is the combined hydrologic and tectonic cycle. On Io, sulfurous compounds are transferred from the interior to the surface reservoirs through a combination of a mantle-sourced magmatic system, vertical cycling of the lithosphere, and a sulfur-dominated crustal thermal system that we here call the "theothermal" system. We present a geochemical analysis of this process using previously inferred temperature and oxygen fugacity constraints of Pele's basaltic magma to determine the behavior of sulfur in the ionian magmas. Sulfate to sulfide ratios of Pele's magma are -4.084 ± 0.6 and -6.442 ± 0.7 log10 units, comparable to or lower than those of mid-ocean ridge basalts. This reflects the similarity of Io's oxidation state with Earth's depleted mantle as previously suggested by Zolotov and Fegley (Zolotov, M.Y., Fegley, B. [2000]. Geophys. Res. Lett. 27, 2789-2792). Our calculated limits of sulfur solubility in melts from Pele's patera (˜1100-1140 ppm) are also comparable to terrestrial mid-ocean ridge basalts, reflecting a compositional similarity of mantle sources. We propose that the excess sulfur obvious on Io's surface comes from two sources: (1) an insoluble sulfide liquid phase in the magma and (2) theothermal near-surface recycling.

  17. Diesel Emission Control -- Sulfur Effects (DECSE) Program; Phase I Interim Date Report No. 3: Diesel Fuel Sulfur Effects on Particulate Matter Emissions

    Energy Technology Data Exchange (ETDEWEB)

    DOE; ORNL; NREL; EMA; MECA

    1999-11-15

    The Diesel Emission Control-Sulfur Effects (DECSE) is a joint government/industry program to determine the impact of diesel fuel sulfur levels on emission control systems whose use could lower emissions of nitrogen oxides (NO{sub x}) and particulate matter (PM) from on-highway trucks in the 2002--2004 model years. Phase 1 of the program was developed with the following objectives in mind: (1) evaluate the effects of varying the level of sulfur content in the fuel on the emission reduction performance of four emission control technologies; and (2) measure and compare the effects of up to 250 hours of aging on selected devices for multiple levels of fuel sulfur content. This interim report covers the effects of diesel fuel sulfur level on particulate matter emissions for four technologies.

  18. COMPONENT DEVELOPMENT NEEDS FOR THE HYBRID SULFUR ELECTROLYZER

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D; Hector Colon-Mercado, H; Mark Elvington, M

    2008-05-30

    Fiscal year 2008 studies in electrolyzer component development have focused on the characterization of membrane electrode assemblies (MEA) after performance tests in the single cell electrolyzer, evaluation of electrocatalysts and membranes using a small scale electrolyzer and evaluating the contribution of individual cell components to the overall electrochemical performance. Scanning electron microscopic (SEM) studies of samples taken from MEAs testing in the SRNL single cell electrolyzer test station indicates a sulfur-rich layer forms between the cathode catalyst layer and the membrane. Based on a review of operating conditions for each of the MEAs evaluated, we conclude that the formation of the layer results from the reduction of sulfur dioxide as it passes through the MEA and reaches the catalyst layer at the cathode-membrane interface. Formation of the sulfur rich layer results in partial delamination of the cathode catalyst layer leading to diminished performance. Furthermore we believe that operating the electrolyzer at elevated pressure significantly increases the rate of formation due to increased adsorption of hydrogen on the internal catalyst surface. Thus, identification of a membrane that exhibits much lower transport of sulfur dioxide is needed to reduce the quantity of sulfur dioxide that reaches the cathode catalyst and is reduced to produce the sulfur-rich layer. Three candidate membranes are currently being evaluated that have shown promise from preliminary studies, (1) modified Nafion{reg_sign}, (2) polybenzimidazole (PBI), and (3) sulfonated Diels Alder polyphenylene (SDAPP). Testing examined the activity for the sulfur dioxide oxidation of platinum (Pt) and platinum-alloy catalysts in 30 wt% sulfuric acid solution. Linear sweep voltammetry showed an increase in activity when catalysts in which Pt is alloyed with non-noble transition metals such as cobalt and chromium. However when Pt is alloyed with noble metals, such as iridium or ruthenium

  19. Sulfur polymer cement encapsulation of RCRA toxic metals and metal oxides

    International Nuclear Information System (INIS)

    Calhoun, C.L. Jr.; Nulf, L.E.; Gorin, A.H.

    1995-06-01

    A study was conducted to determine the suitability of Sulfur Polymer Cement (SPC) encapsulation technology for the stabilization of RCRA toxic metal and metal oxide wastes. In a series of bench-scale experiments, the effects of sodium sulfide additions to the waste mixture, residence time, and temperature profile were evaluated. In addition, an effort was made to ascertain the degree to which SPC affords chemical stabilization as opposed to physical encapsulation. Experimental results have demonstrated that at the 25 wt % loading level, SPC can effectively immobilize Cr, Cr 2 O 3 , Hg, Pb, and Se to levels below regulatory limits. SPC encapsulation also has been shown to significantly reduce the leachability of other toxic compounds including PbO, PbO 2 , As 2 O 3 , BaO, and CdO. In addition, data has confirmed sulfide conversion of Hg, Pb, PbO, PbO 2 , and BaO as the product of their reaction with SPC

  20. An overview on the removal of synthetic dyes from water by electrochemical advanced oxidation processes.

    Science.gov (United States)

    Nidheesh, P V; Zhou, Minghua; Oturan, Mehmet A

    2018-04-01

    Wastewater containing dyes are one of the major threats to our environment. Conventional methods are insufficient for the removal of these persistent organic pollutants. Recently much attention has been received for the oxidative removal of various organic pollutants by electrochemically generated hydroxyl radical. This review article aims to provide the recent trends in the field of various Electrochemical Advanced Oxidation Processes (EAOPs) used for removing dyes from water medium. The characteristics, fundamentals and recent advances in each processes namely anodic oxidation, electro-Fenton, peroxicoagulation, fered Fenton, anodic Fenton, photoelectro-Fenton, sonoelectro-Fenton, bioelectro-Fenton etc. have been examined in detail. These processes have great potential to destroy persistent organic pollutants in aqueous medium and most of the studies reported complete removal of dyes from water. The great capacity of these processes indicates that EAOPs constitute a promising technology for the treatment of the dye contaminated effluents. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Thermodynamic Analysis of an Integrated Solid Oxide Fuel Cell Cycle with a Rankine Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2010-01-01

    Hybrid systems consisting of Solid Oxide Fuel Cells (SOFC) on the top of a Steam Turbine (ST) are investigated. The plants are fired by natural gas (NG). A desulfurization reactor removes the sulfur content in the fuel while a pre-reformer breaks down the heavier hydrocarbons. The pre-treated fuel......% are achieved which is considerably higher than the conventional Combined Cycles (CC). Both ASR (Adiabatic Steam Reformer) and CPO (Catalytic Partial Oxidation) fuel pre-reformer reactors are considered in this investigation....

  2. Obligate sugar oxidation in Mesotoga spp., phylum Thermotogae, in the presence of either elemental sulfur or hydrogenotrophic sulfate-reducers as electron acceptor.

    Science.gov (United States)

    Fadhlaoui, Khaled; Ben Hania, Wagdi; Armougom, Fabrice; Bartoli, Manon; Fardeau, Marie-Laure; Erauso, Gaël; Brasseur, Gaël; Aubert, Corinne; Hamdi, Moktar; Brochier-Armanet, Céline; Dolla, Alain; Ollivier, Bernard

    2018-01-01

    Mesotoga prima strain PhosAc3 is a mesophilic representative of the phylum Thermotogae comprising only fermentative bacteria so far. We show that while unable to ferment glucose, this bacterium is able to couple its oxidation to reduction of elemental sulfur. We demonstrate furthermore that M. prima strain PhosAc3 as well as M. prima strain MesG1 and Mesotoga infera are able to grow in syntrophic association with sulfate-reducing bacteria (SRB) acting as hydrogen scavengers through interspecies hydrogen transfer. Hydrogen production was higher in M. prima strain PhosAc3 cells co-cultured with SRB than in cells cultured alone in the presence of elemental sulfur. We propose that the efficient sugar-oxidizing metabolism by M. prima strain PhosAc3 in syntrophic association with a hydrogenotrophic sulfate-reducing bacterium can be extrapolated to all members of the Mesotoga genus. Genome comparison of Thermotogae members suggests that the metabolic difference between Mesotoga and Thermotoga species (sugar oxidation versus fermentation) is mainly due to the absence of the bifurcating [FeFe]-hydrogenase in the former. Such an obligate oxidative process for using sugars, unusual within prokaryotes, is the first reported within the Thermotogae. It is hypothesized to be of primary ecological importance for growth of Mesotoga spp. in the environments that they inhabit. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Developing clean fuels: Novel techniques for desulfurization

    Science.gov (United States)

    Nehlsen, James P.

    The removal of sulfur compounds from petroleum is crucial to producing clean burning fuels. Sulfur compounds poison emission control catalysts and are the source of acid rain. New federal regulations require the removal of sulfur in both gasoline and diesel to very low levels, forcing existing technologies to be pushed into inefficient operating regimes. New technology is required to efficiently produce low sulfur fuels. Two processes for the removal of sulfur compounds from petroleum have been developed: the removal of alkanethiols by heterogeneous reaction with metal oxides; and oxidative desulfurization of sulfides and thiophene by reaction with sulfuric acid. Alkanethiols, common in hydrotreated gasoline, can be selectively removed and recovered from a hydrocarbon stream by heterogeneous reaction with oxides of Pb, Hg(II), and Ba. The choice of reactive metal oxides may be predicted from simple thermodynamic considerations. The reaction is found to be autocatalytic, first order in water, and zero order in thiol in the presence of excess oxide. The thiols are recovered by reactive extraction with dilute oxidizing acid. The potential for using polymer membrane hydrogenation reactors (PEMHRs) to perform hydrogenation reactions such as hydrodesulfurization is explored by hydrogenating ketones and olefins over Pt and Au group metals. The dependence of reaction rate on current density suggests that the first hydrogen addition to the olefin is the rate limiting step, rather than the adsorption of hydrogen, for all of the metals tested. PEMHRs proved unsuccessful in hydrogenating sulfur compounds to perform HDS. For the removal of sulfides, a two-phase reactor is used in which concentrated sulfuric acid oxidizes aromatic and aliphatic sulfides present in a hydrocarbon solvent, generating sulfoxides and other sulfonated species. The polar oxidized species are extracted into the acid phase, effectively desulfurizing the hydrocarbon. A reaction scheme is proposed for this

  4. Activation of Graphene Oxide with Hydrochloric Acid for Nitrate Removal from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Abolghasem Alighardashi

    2017-11-01

    Full Text Available Long-term drinking of nitrate-contaminated water poses a serious risk to human health. The present study explores the possibility of enhancing the adsorption capacity of graphene oxide via activation with hydrochloric acid for nitrate removal from aqueous solutions. Experiments were performed in a batch reactor in which such major factors as pH, reaction time, and concentrations of both graphene oxide (GO and activated graphene oxide (AGO were used as variables. Nitrate removal efficiency was investigated using the One-Way ANOVA statistical test and SPSS-16 software. The chemical composition and solid structure of the synthesized AGO were analyzed using FE-SEM coupled with energy dispersive spectrometry (EDS. The micropore volumes of the samples were determined using the BET and BJH. The predominant composition (52% of the synthesized AGO was C and its mean pore diameter was 26.896 nm. The maximum adsorption capacity of AGO was estimated at 3333.33 mg/g. Based on the results, the AGO nano-structure may be recomended as a new means for nitrate removal from aqueous solutions.

  5. NONEQUILIBRIUM SULFUR CAPTURE AND RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

    International Nuclear Information System (INIS)

    Dr. Bert Zauderer

    1999-01-01

    Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. They are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, slag must be rapidly drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to perform a series of tests to determine the factors that control the retention of the sulfur in the slag. 36 days of testing on the combustor were completed prior to the end of this reporting period, 12/31/98. This compares with 16 tests required in the original project plan. Combustor tests in early 1997 with high (37%) ash, Indian coal confirmed that high slag mass flow rates of about 500 lb/hr resulted in retention in the slag of up to 20% of the injected sulfur content mineral matter. To further increase the slag flow rate, rice husks, which contain 20% ash, and rice husk char, which contain 70% ash, were co-fired with coal in the combustor. A series of 13 combustor tests were performed in fourth quarter of 1997 and a further 6 tests were performed in January 1998 and in the summer of 1998. The test objective was to achieve slag flow rates between 500 and 1,000 lb/hr. Due to the very low bulk density of rice husk, compared to pulverized coal, almost the entire test effort focused on developing methods for feeding the rice husks into combustor. In the last test of December 1997, a peak mineral matter, injection rate of 592 lb/hr was briefly achieved by injection of coal, rice husk char, gypsum, and limestone into the combustor. However, no significant sulfur concentration was measured in the slag removed from the combustor. The peak injection rate reached with biomass in the 1997 tests was 310 lb/hr with rice husk, and 584 lb/hr with rice husk char

  6. Removal of iodomethane from air using a plot-scale corona discharge scrubber

    International Nuclear Information System (INIS)

    Dickson, L.W.; Toft-Hall, A.; Torgerson, D.F.

    1985-12-01

    This report presents the results of a study of the removal of iodomethane from air using a pilot-scale corona discharge scrubber. The removal was measured in the following parameter ranges: bulk air flow, 30 to 350 m 3 /h; initial CH 3 I concentration, 6 to 230 μmol/m 3 ; and discharge current, 0 to 75 mA DC (negative polarity). Approximately five to ten moles of iodomethane are removed per mole of electrons added to the air stream at a discharge voltage of ∼ 10 kV. This removal efficiency suggests that both ion-molecule and radical-molecule reactions may be important in the removal of iodomethane from air in a corona discharge. The results of this pilot-scale demonstration indicate that a corona discharge scrubber would be suitable for removing iodine species from air as part of the emergency filtered-air discharge system of a nuclear reactor. The application of this technology to the control of nitrogen oxide, sulfur dioxide and hydrogen sulfide emissions is being investigated. 15 refs

  7. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1 Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2 Magnesium oxide can obviously improve the sulfur fixation performance of Bayer red mud and up to a maximum sulfur fixation rate of 47 wt% at adding 1 wt% magnesium oxide. (3 Dolomite enhanced the sulfur