Sample records for dilute sulfuric acid

  1. Sulfuric Acid and Water: Paradoxes of Dilution

    ERIC Educational Resources Information Center

    Leenson, I. A.

    2004-01-01

    On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

  2. Sugar yields from dilute sulfuric acid and sulfur dioxide pretreatments and subsequent enzymatic hydrolysis of switchgrass

    E-print Network

    California at Riverside, University of

    Sugar yields from dilute sulfuric acid and sulfur dioxide pretreatments and subsequent enzymatic%, and 10% wt.% of dry biomass were also tested at 180 °C for 10 min. Sugar yields were tracked for pretreatment and subsequent enzymatic hydrolysis to identify conditions for the highest total sugar yields

  3. Modeling sucrose hydrolysis in dilute sulfuric acid solutions at pretreatment conditions for lignocellulosic biomass

    Microsoft Academic Search

    Shane Bower; Ranil Wickramasinghe; Nicholas J. Nagle; Daniel J. Schell

    2008-01-01

    Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25g\\/l sucrose with 0.1–2.0% (w\\/w) sulfuric acid concentrations were treated at temperatures of 160–200°C for 3–12min.

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

    PubMed Central

    2013-01-01

    Background Use of lignocellulosic biomass has received attention lately because it can be converted into various versatile chemical compounds by biological processes. In this study, a two-step pretreatment with dilute sulfuric acid and aqueous ammonia was performed efficiently on rice straw to obtain fermentable sugar. The soaking in aqueous ammonia process was also optimized by a statistical method. Results Response surface methodology was employed. The determination coefficient (R2) value was found to be 0.9607 and the coefficient of variance was 6.77. The optimal pretreatment conditions were a temperature of 42.75°C, an aqueous ammonia concentration of 20.93%, and a reaction time of 48 h. The optimal enzyme concentration for saccharification was 30 filter paper units. The crystallinity index was approximately 60.23% and the Fourier transform infrared results showed the distinct peaks of glucan. Ethanol production using Saccharomyces cerevisiae K35 was performed to verify whether the glucose saccharified from rice straw was fermentable. Conclusions The combined pretreatment using dilute sulfuric acid and aqueous ammonia on rice straw efficiently yielded fermentable sugar and achieved almost the same crystallinity index as that of ?-cellulose. PMID:23898802

  5. A novel diffusion-biphasic hydrolysis coupled kinetic model for dilute sulfuric acid pretreatment of corn stover.

    PubMed

    Chen, Longjian; Zhang, Haiyan; Li, Junbao; Lu, Minsheng; Guo, Xiaomiao; Han, Lujia

    2015-02-01

    Kinetic experiments on the dilute sulfuric acid pretreatment of corn stover were performed. A high xylan removal and a low inhibitor concentration were achieved by acid pretreatment. A novel diffusion-hydrolysis coupled kinetic model was proposed. The contribution to the xylose yield was analyzed by the kinetic model. Compared with the inhibitor furfural negatively affecting xylose yield, the fast and slow-hydrolyzing xylan significantly contributed to the xylose yield, however, their dominant roles were dependent on reaction temperature and time. The impact of particle size and acid concentration on the xylose yield were also investigated. The diffusion process may significantly influence the hydrolysis of large particles. Increasing the acid concentration from 0.15 M to 0.30 M significantly improved the xylose yield, whereas the extent of improvement decreased to near-quantitative when further increasing acid loading. These findings shed some light on the mechanism for dilute sulfuric acid hydrolysis of corn stover. PMID:25479388

  6. Optimization of dilute sulfuric acid pretreatment and enzymatic saccharification of corn stover for efficient ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dilute acid pretreatment is a promising pretreatment technology for conversion of lignocellulosic biomass to fuel ethanol. Corn stover (supplied by a local farmer) used in this study contained 37.0±0.4% cellulose, 31.3±0.6% hemicelluloses, and 17.8±0.2% lignin. Generation of fermentable sugars from ...

  7. Dilute Sulfuric Acid Pretreatment of Agricultural and Agro-Industrial Residues for Ethanol Production

    NASA Astrophysics Data System (ADS)

    Martin, Carlos; Alriksson, Björn; Sjöde, Anders; Nilvebrant, Nils-Olof; Jönsson, Leif J.

    The potential of dilute-acid prehydrolysis as a pretreatment method for sugarcane bagasse, rice hulls, peanut shells, and cassava stalks was investigated. The prehydrolysis was performed at 122°C during 20, 40, or 60 min using 2% H2SO4 at a solid-to-liquid ratio of 1?10. Sugar formation increased with increasing reaction time. Xylose, glucose, arabinose, and galactose were detected in all of the prehydrolysates, whereas mannose was found only in the prehydrolysates of peanut shells and cassava stalks. The hemicelluloses of bagasse were hydrolyzed to a high-extent yielding concentrations of xylose and arabinose of 19.1 and 2.2 g/L, respectively, and a xylan conversion of more than 80%. High-glucose concentrations (26-33.5 g/L) were found in the prehydrolysates of rice hulls, probably because of hydrolysis of starch of grain remains in the hulls. Peanut shells and cassava stalks rendered low amounts of sugars on prehydrolysis, indicating that the conditions were not severe enough to hydrolyze the hemicelluloses in these materials quantitatively. All prehydrolysates were readily fermentable by Saccharomyces cerevisiae. The dilute-acid prehydrolysis resulted in a 2.7-to 3.7-fold increase of the enzymatic convertibility of bagasse, but was not efficient for improving the enzymatic hydrolysis of peanut shells, cassava stalks, or rice hulls.

  8. Feasibility of filamentous fungi for biofuel production using hydrolysate from dilute sulfuric acid pretreatment of wheat straw

    PubMed Central

    2012-01-01

    Background Lipids produced from filamentous fungi show great promise for biofuel production, but a major limiting factor is the high production cost attributed to feedstock. Lignocellulosic biomass is a suitable feedstock for biofuel production due to its abundance and low value. However, very limited study has been performed on lipid production by culturing oleaginous fungi with lignocellulosic materials. Thus, identification of filamentous fungal strains capable of utilizing lignocellulosic hydrolysates for lipid accumulation is critical to improve the process and reduce the production cost. Results The growth performances of eleven filamentous fungi were investigated when cultured on glucose and xylose. Their dry cell weights, lipid contents and fatty acid profiles were determined. Six fungal strains with high lipid contents were selected to culture with the hydrolysate from dilute sulfuric acid pretreatment of wheat straw. The results showed that all the selected fungal strains were able to grow on both detoxified liquid hydrolysate (DLH) and non-detoxified liquid hydrolysate (NDLH). The highest lipid content of 39.4% was obtained by Mortierella isabellina on NDLH. In addition, NDLH with some precipitate could help M. isabellina form pellets with an average diameter of 0.11?mm. Conclusion This study demonstrated the possibility of fungal lipid production from lignocellulosic biomass. M. isabellina was the best lipid producer grown on lignocellulosic hydrolysates among the tested filamentous fungi, because it could not only accumulate oils with a high content by directly utilizing NDLH to simplify the fermentation process, but also form proper pellets to benefit the downstream harvesting. Considering the yield and cost, fungal lipids from lignocellulosic biomass are promising alternative sources for biodiesel production. PMID:22824058

  9. Influence of organic additives on the corrosion of iron-based amorphous alloys in dilute sulfuric acid solution

    SciTech Connect

    Frignani, A.; Trabanelli, G.

    1999-07-01

    Some N-containing or S-containing organic substances and some acetylenic alcohols were tested as inhibitors of the corrosive attack suffered by Fe-based metallic glasses in deaerated 0.1 N sulfuric acid (H{sub 2}SO{sub 4}) solution at 25 C. It was verified that the specific action these compounds exerted on the corrosion process of the amorphous alloys was similar to the one these compounds exerted on polycrystalline iron. The most efficient substances were those containing a sulfur atom with available lone pairs, which chiefly inhibited the anodic reaction of both metal specimens. Owing to the chemical and physical homogeneity of the amorphous alloy, the chemisorbed inhibitor film that formed on the glassy surface was more stable and protective than that formed on the polycrystalline iron.

  10. Sulfuric Acid on Europa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Frozen sulfuric acid on Jupiter's moon Europa is depicted in this image produced from data gathered by NASA's Galileo spacecraft. The brightest areas, where the yellow is most intense, represent regions of high frozen sulfuric acid concentration. Sulfuric acid is found in battery acid and in Earth's acid rain.

    This image is based on data gathered by Galileo's near infrared mapping spectrometer.

    Europa's leading hemisphere is toward the bottom right, and there are enhanced concentrations of sulfuric acid in the trailing side of Europa (the upper left side of the image). This is the face of Europa that is struck by sulfur ions coming from Jupiter's innermost moon, Io. The long, narrow features that crisscross Europa also show sulfuric acid that may be from sulfurous material extruded in cracks.

    Galileo, launched in 1989, has been orbiting Jupiter and its moons since December 1995. JPL manages the Galileo mission for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

  11. Corrosion resistance and behavior of construction materials exposed to dilute sulfuric acid at elevated temperatures under static conditions

    SciTech Connect

    Nguyen, D.T.

    1994-10-01

    Laboratory investigation has been undertaken to determine the electrochemical behavior and corrosion resistance of various construction materials in a simulated hydrolysis environment (5 wt % sulfuric acid) at temperatures ranging from 90 to 220C. Tests were performed in an autoclave-type electrochemical cell. The corrosion behavior of the test materials was determined using computer-controlled DC potentiodynamic polarization. Corrosion rates of the test materials were determined using AC impedance techniques. Among the stainless steels tested, only alloy N08026 (Carpenter 20Mo-6) performed satisfactory up to a temperature of 100C. The alloy passivated spontaneously in the environment and corroded at a rate of less than 2 mpy. None of the stainless steels tested could be used at 120{degrees}C or above. A number of nickel-based alloys tested had good corrosion resistance up to 100C, but their corrosion rate exceeded 2 mpy at higher temperatures. Zirconium alloys were satisfactory up to 180C. Only tantalum and a tantalum-niobium alloy were satisfactory up to 220C.

  12. Zirconium in sulfuric acid applications

    SciTech Connect

    Webster, R.T.; Yau, T.L.

    1986-02-01

    Zirconium is one of the few metals that resists attack by sulfuric acid at concentrations up to 75% and temperatures to boiling and above. This capability makes zirconium a good structural metal for use in 40 to 65% H/sub 2/SO/sub 4/ up to boiling temperatures and for weak acid concentrations at elevated temperatures. Zirconium's corrosion properties in sulfuric acid solutions are compared with nickel base alloys. Examples of applications and limitations in the use of zirconium are presented.

  13. Dilute Acid and Autohydrolysis Pretreatment Bin Yang and Charles E. Wyman

    E-print Network

    California at Riverside, University of

    Chapter 8 Dilute Acid and Autohydrolysis Pretreatment Bin Yang and Charles E. Wyman Summary. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85­95% of the maximum possible versus only about 65% if no acid

  14. Science Notes: Dilution of a Weak Acid

    ERIC Educational Resources Information Center

    Talbot, Christopher; Wai, Chooi Khee

    2014-01-01

    This "Science note" arose out of practical work involving the dilution of ethanoic acid, the measurement of the pH of the diluted solutions and calculation of the acid dissociation constant, K[subscript a], for each diluted solution. The students expected the calculated values of K[subscript a] to be constant but they found that the…

  15. Comparison of Nitric Acid and Sulfuric Acid Dissolution of Samples from the 242-16H Evaporator Pot

    SciTech Connect

    Wilmarth, W.R.

    2000-08-29

    Researchers completed initial studies to determine the feasibility of chemically cleaning the 242-16H High Level Waste Evaporator pot using sulfuric acid. In general, sulfuric acid dissolution of the aluminosilicate material proves of limited value. Dilute nitric acid systems still appear to give the best cleaning performance. The author plans further testing of gadolinium in nitric acid.

  16. Characterization and fermentation of dilute-acid hydrolyzates from wood

    Microsoft Academic Search

    Mohammad J. Taherzadeh; C. Niklasson; G. Liden; R. Eklund; L. Gustafsson

    1997-01-01

    Dilute-acid hydrolyzates from alder, aspen, birch, willow, pine, and spruce were fermented without prior detoxification. The hydrolyzates were prepared by a one-stage hydrolysis process using sulfuric acid (5 g\\/L) at temperatures between 188 and 234 C and with a holding time of 7 min. The fermentations were carried out anaerobically by Saccharomyces cerevisiae (10 g of d.w.\\/L) at a temperature

  17. Dilute sulfuric acid pretreatment of corn stover for enzymatic hydrolysis and efficient ethanol production by recombinant Escherichia coli FBR5 without detoxification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A pretreatment strategy for dilute H2SO4 pretreatment of corn stover was developed for the purpose of reducing the generation of inhibitory substances during pretreatment so that a detoxification step is not required prior to fermentation while maximizing the sugar yield. We have optimized dilute su...

  18. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

  19. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

  20. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

  1. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

  2. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

  3. The generation of fermentation inhibitors during dilute acid hydrolysis of softwood

    Microsoft Academic Search

    Simona Larsson; Eva Palmqvist; Bärbel Hahn-Hägerdal; Charlotte Tengborg; Kerstin Stenberg; Guido Zacchi; Nils-Olof Nilvebrant

    1999-01-01

    The influence of the severity of dilute sulfuric acid hydrolysis of spruce (softwood) on sugar yield and on the fermentability of the hydrolysate by Saccharomyces cerevisiae (Baker’s yeast) was investigated. Fermentability was assessed as the ethanol yield on fermentable sugars (mannose and glucose) and the mean volumetric productivity (4 h). The hydrolysis conditions, residence time, temperature, and sulfuric acid concentration

  4. Effect of dilute acid on the accelerated weathering of wood

    SciTech Connect

    Williams, R.S.

    1988-02-01

    Western red cedar (Thuja plicata) specimens were soaked in acid solutions to determine the effect of acid conditions (such as low pH fog) on the weathering of wood. Daily 1-hour soaking in dilute sulfurous, sulfuric, or nitric acid (pH 2.0, 2.5, 3.0, 3.5, or 4.0) increased the rate of accelerated (xenon arc) weathering of the specimens compared to controls soaked in distilled/deionized water. Weathering was manifested as the erosion rate of the wood surface and was determined gravimetrically be fitting the weight loss over time to a linear model. This method detected significant differences between acid-treated specimens and untreated controls within 300 hours of accelerated weathering. The erosion rate was dependent on the acid type and pH. Sulfurous acid treatment caused the fastest rate of erosion, followed by sulfuric then nitric acid. None of the acids affected the erosion rate at pH 3.5 or above. Below this threshold, the rate of erosion increased as the hydrogen ion concentration increased. Sugar analysis of residues from the acids and the distilled water used to soak the wood indicated acid-dependent degradation of polysaccharides.

  5. Radiolysis of Sulfuric Acid, Sulfuric Acid Monohydrate, and Sulfuric Acid Tetrahydrate and Its Relevance to Europa

    NASA Technical Reports Server (NTRS)

    Loeffler, M. J.; Hudson, R. L.; Moore, M. H.; Carlson, R. W.

    2011-01-01

    We report laboratory studies on the 0.8 MeV proton irradiation of ices composed of sulfuric acid (H2SO4), sulfuric acid monohydrate (H2SO4 H2O), and sulfuric acid tetrahydrate (H2SO4 4H2O) between 10 and 180 K. Using infrared spectroscopy, we identify the main radiation products as H2O, SO2, (S2O3)x, H3O+, HSO4(exp -), and SO4(exp 2-). At high radiation doses, we find that H2SO4 molecules are destroyed completely and that H2SO4 H2O is formed on subsequent warming. This hydrate is significantly more stable to radiolytic destruction than pure H2SO4, falling to an equilibrium relative abundance of 50% of its original value on prolonged irradiation. Unlike either pure H2SO4 or H2SO4 H2O, the loss of H2SO4 4H2O exhibits a strong temperature dependence, as the tetrahydrate is essentially unchanged at the highest irradiation temperatures and completely destroyed at the lowest ones, which we speculate is due to a combination of radiolytic destruction and amorphization. Furthermore, at the lower temperatures it is clear that irradiation causes the tetrahydrate spectrum to transition to one that closely resembles the monohydrate spectrum. Extrapolating our results to Europa s surface, we speculate that the variations in SO2 concentrations observed in the chaotic terrains are a result of radiation processing of lower hydration states of sulfuric acid and that the monohydrate will remain stable on the surface over geological times, while the tetrahydrate will remain stable in the warmer regions but be destroyed in the colder regions, unless it can be reformed by other processes, such as thermal reactions induced by diurnal cycling.

  6. Dilute acid hydrolysis of lignocellulosic biomass

    Microsoft Academic Search

    P. Lenihan; A. Orozco; E. O’Neill; M. N. M. Ahmad; D. W. Rooney; G. M. Walker

    2010-01-01

    The overall aim of this work was to establish the optimum conditions for acid hydrolysis of hemicellulosic biomass in the form of potato peel. The hydrolysis reaction was undertaken in a 1l high pressure pilot batch reactor using dilute phosphoric acid. Analysis of the decomposition rate of hemicellulosic biomass (namely Cellulose, Hemicellulose and lignin) was undertaken using HPLC of the

  7. Reduction of sulfuric acid by natural gas

    SciTech Connect

    Kogtev, S.E.; Nikandrov, I.S.

    1987-12-01

    The reduction of sulfuric acid to sulfur dioxide was studied to obtain a higher yield of sulfur dioxide. The reactions which take place in the presence of excess methane were listed. Gibbs energy reactions were presented showing the thermodynamic probability for the occurrence of the reactions within a wide temperature range. Gas analysis for the content of sulfur and carbon dioxides, methane hydrogen, hydrogen sulfate, and carbon monoxide was performed chromatographically using a katharometer and sequential columns packed with Polysorb 1 and NaX zeolite. It was shown that through high-temperature reduction of sulfuric acid by natural gas, the yield of sulfur dioxide could be raised to 100% at 1173 K.

  8. Comparative Study of SPORL and Dilute Acid Pretreatments of Spruce for Cellulosic Ethanol Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The performance of two pretreatment methods, Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose (SPORL) and Dilute Acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production under the same conditions of temperature (180°C), time (30 min), sulfuric acid loading...

  9. Analysis of solids resulted from dilute-acid pretreatment of lignocellulosic biomass

    Microsoft Academic Search

    T. Hsu; Q. Nguyen

    1995-01-01

    Lignocellulosic biomass materials were pretreated with dilute sulfuric acid, followed by analysis of partially and extensively washed pretreated solids. It is demonstrated that it is of crucial importance to perform extensive washing for accurate carbohydrate analyses to be obtained. Klason lignin, acid-soluble lignin, and ash analyses were not significantly affected by the extent of washing.

  10. Surface Pretreatment Based On Dilute Hexafluorozirconic Acid

    Microsoft Academic Search

    Y. Zhai; Z. Zhao; G. S. Frankel; J. Zimmerman; T. Bryden; W. Fristad

    Two surface pretreatments based on dilute hexafluorozirconic acid (FZ) solution, a simple FZ and a modified FZ or MFZ, were studied as replacements for the phosphating process. The FZ conversion coatings were deposited on cold rolled steel (CRS) substrates by immersion treatment. AFM images reveal that the coating surface exhibited small features tens of nm in size and clusters of

  11. Sulfuric acid/hydrogen peroxide rinsing study

    SciTech Connect

    Clews, P.J.; Nelson, G.C.; Matlock, C.A. [and others

    1995-12-01

    Sulfuric acid hydrogen peroxide mixtures (SPM) are commonly used in the semiconductor industry to remove organic contaminants from wafer surfaces. This viscous solution is very difficult to rinse off water surfaces. Various rinsing conditions were tested and the resulting residual acid left on the water surface was measured. Particle growth resulting from incomplete rinse is correlated with the amount of sulfur on the wafer surface measured by Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS). The amount of sulfur on the wafer structure after the rinse step is strongly affected by the wafer film type and contact angle prior to the SPM clean.

  12. Hydrolysis of dilute acid-pretreated cellulose under mild hydrothermal conditions.

    PubMed

    Chimentćo, R J; Lorente, E; Gispert-Guirado, F; Medina, F; López, F

    2014-10-13

    The hydrolysis of dilute acid-pretreated cellulose was investigated in a conventional oven and under microwave heating. Two acids--sulfuric and oxalic--were studied. For both hydrothermal conditions (oven and microwave) the resultant total organic carbon (TOC) values obtained by the hydrolysis of the cellulose pretreated with sulfuric acid were higher than those obtained by the hydrolysis of the cellulose pretreated with oxalic acid. However, the dicarboxylic acid exhibited higher hydrolytic efficiency towards glucose. The hydrolysis of cellulose was greatly promoted by microwave heating. The Rietveld method was applied to fit the X-ray patterns of the resultant cellulose after hydrolysis. Oxalic acid preferentially removed the amorphous region of the cellulose and left the crystalline region untouched. On the other hand, sulfuric acid treatment decreased the ordering of the cellulose by partially disrupting its crystalline structure. PMID:25037336

  13. CONSTRUCTION OF A PROTOTYPE SULFURIC ACID MIST MONITOR

    EPA Science Inventory

    A prototype sulfuric acid mist monitor has been constructed for the purpose of detecting sulfuric acid-sulfur trioxide. The monitor utilized the selective condensation method with subsequent determination of sulfuric acid by measuring the conductivity of an aqueous isopropanol so...

  14. Friction and wear of nickel in sulfuric acid

    NASA Technical Reports Server (NTRS)

    Rengstorff, G. W. P.; Miyoshi, K.; Buckley, D. H.

    1984-01-01

    Experiments were conducted with elemental nickel sliding on aluminum oxide in aerated sulfuric acid in concentrations ranging from very dilute (10 -4 N, i.e., 5 ppm) to very concentrated (96 percent) acid. Load and reciprocating sliding speeds were kept constant. With the most dilute concentration (10 -4 N) no observable corrosion occurred in or outside the wear area. This was used as the base condition to determine the high contribution of corrosion to total wear loss at acid concentrations between 0.5 percent (0.1 N) and 75 percent. Corrosion reached a maximum rate of 100 millimeters per year at 30 percent acid. At the same time, general corrosion outside the wear area was very low, in agreement with published information. It is clear that friction and wear greatly accelerated corrosion in the wear area. At dilute concentrations of 0.001 and 0.01 N, corrosion in the wear area was low, and general corrosion outside was also low, but local outside regions in the direction of the wear motion experienced some enhanced corrosion, apparently due to fluid motion of the acid.

  15. Sulfuric acid in the Venus clouds.

    NASA Technical Reports Server (NTRS)

    Sill, G. T.

    1972-01-01

    The extremely dry nature of the Venus upper atmosphere appears to demand the presence of an efficient desiccating agent as the chief constituent of the clouds of Venus. On the basis of polarization measures it is to be expected that this substance is present as spherical droplets, 1 to 2 microns in diameter, with a refractive index n of 1.46 plus or minus 0.02 at 3500A in the observed region of the atmosphere, with T about equal to 235 K. This substance must have ultraviolet, visible, and infrared reflection properties not inconsistent with the observed spectrum of Venus. Sulfuric acid, of about 86% by weight composition, roughly fulfills the first of these properties. The visible and ultraviolet transmission features of a thin layer of elemental bromine and hydrobromic acid dissolved in sulfuric acid somewhat resemble the Venus spectrum, up to 14 microns. The chemical process postulated for forming sulfuric acid involves the oxidation of sulfur and its compounds to sulfuric acid through the agency of elemental bromine produced by the photolytic decomposition of hydrogen bromide.

  16. Growth of nitric acid hydrates on thin sulfuric acid films

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-01-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  17. Effect of swine manure dilution on ammonia, hydrogen sulfide, carbon dioxide, and sulfur dioxide releases.

    PubMed

    Ni, Ji-Qin; Heber, Albert J; Sutton, Alan L; Kelly, Dan T; Patterson, John A; Kim, Sun-Tae

    2010-11-01

    Animal manure is a significant source of environmental pollution and manure dilution in barn cleaning and slurry storage is a common practice in animal agriculture. The effect of swine manure dilution on releases of four pollutant gases was studied in a 30-day experiment using eight manure reactors divided into two groups. One group was treated with swine manure of 6.71% dry matter and another with manure diluted with water to 3.73% dry matter. Ammonia release from the diluted manure was 3.32 mg min(-1)m(-2) and was 71.0% of the 4.67 mg min(-1)m(-2) from the undiluted manure (P<0.01). Because the ammonia release reduction ratio was lower than the manure dilution ratio, dilution could increase the total ammonia emissions from swine manure, especially in lagoons with large liquid surface areas. Carbon dioxide release of 87.3 mg min(-1)m(-2) from the diluted manure was 56.4% of the 154.8 mg min(-1)m(-2) from the undiluted manure (P<0.01). Manure dry matter was an important factor for carbon dioxide release from manure. No differences were observed between the treatments (P>0.05) for both hydrogen sulfide and sulfur dioxide releases. Therefore, dilution could also significantly increase the total releases of hydrogen sulfide and sulfur dioxide to the environment because dilution adds to the total manure volume and usually also increases the total gas release surface area. PMID:20850169

  18. Sulfuric acid thermoelectrochemical system and method

    DOEpatents

    Ludwig, Frank A. (Rancho Palos Verdes, CA)

    1989-01-01

    A thermoelectrochemical system in which an electrical current is generated between a cathode immersed in a concentrated sulfuric acid solution and an anode immersed in an aqueous buffer solution of sodium bisulfate and sodium sulfate. Reactants consumed at the electrodes during the electrochemical reaction are thermochemically regenerated and recycled to the electrodes to provide continuous operation of the system.

  19. EFFECTS OF SULFURIC ACID AEROSOLS ON VEGETATION

    EPA Science Inventory

    A continuous flow system for exposing plants to submicron aerosols of sulfuric acid has been developed and an operational model has been constructed. Exposure chambers have been designed to allow simultaneous exposures of the same plant to aerosol and control environments. All su...

  20. Zirconium in a sulfuric acid pickling application

    SciTech Connect

    Yau, T.L.

    1988-01-01

    In 1972, Goodyear discovered that zirconium was an ideal material to construct heating coils for sulfuric acid picking tanks. Recently, localized corrosion and high uniform corrosion were reported with certain zirconium coils. The problems could be attributed to the contamination of chloride and/or fluoride ions. Results of electrochemical and immersion tests are used to discuss the effects of acid concentration and acid impurities, such as iron, chloride and fluoride ions, on zirconium's corrosion properties in H/sub 2/SO/sub 4/. Possible sources for acid impurities are identified. Recommendations are made for steel picking when zirconium equipment is used.

  1. Heterogeneous interaction of peroxyacetyl nitrate with liquid sulfuric acid

    Microsoft Academic Search

    Renyi Zhang; Ming-Taun Leu

    1997-01-01

    The uptake of peroxyacetyl nitrate (PAN) on liquid sulfuric acid surfaces has been investigated using a fast-flow reactor coupled to a chemical ionization mass spectrometer. PAN was observed to be reversibly adsorbed on sulfuric acid. From the time-dependent uptake, Henry's law solubility constant of PAN in sulfuric acid was obtained. The measured solubility constant was found to depend strongly on

  2. Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

    NASA Technical Reports Server (NTRS)

    Kallenborn, K. J.; Emmons, J. R.

    1995-01-01

    Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.

  3. Sulfuric acid thermoelectrochemical system and method

    SciTech Connect

    Ludwig, F.A.

    1989-03-07

    This patent describes a thermoelectrochemical system for generating an electrical current including: an electrochemical cell having a cathode compartment and an anode compartment, the compartments having a common ion permeable separation wall; a cathode comprising lead oxide and an anode comprising lead sulfate located within their respective compartments, the cathode and anode being connectable externally of the cell for generation of the electrical current therebetween; a cathode solution comprising concentrated sulfuric acid located in the cathode compartment and in contract with the cathode wherein water is generated or collected and sulfuric acid is consumed at the cathode during generation of the electrical current; an anode solution comprising an aqueous buffer solution of sodium sulfate and sodium bisulfate located in the anode compartment and in contact with the anode wherein sodium bisulfate is generated and sodium sulfate is consumed at the anode during generation of the electrical current.

  4. Heat Transfer Characteristics of Sulfur and Sulfur Diluted with Hydrogen Sulfide Flowing Through Circular Tubes 

    E-print Network

    Stone, Porter Walwyn

    1960-01-01

    disadvantages, it has characteristics which favor its use as a reactor coolant. These characteristics may be classified as nuclear, physical and chemical. Nuclear. Sulfur has a relatively low tendency to absorb neutrons, its absorption cross...-section for thermal neutrons being 0. 130 barns. For comparison, water has an absorption cross-section of 0. 58 barns for thermal neutrons (2) . Sulfur is not activated by exposure to neutron flux in such a way as to produce a radioactive isotope which...

  5. 46 CFR 153.556 - Special requirements for sulfuric acid and oleum.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...false Special requirements for sulfuric acid and oleum. 153.556 Section 153...556 Special requirements for sulfuric acid and oleum. (a) Except as prescribed...containment systems carrying sulfuric acid, oleum, or contaminated sulfuric...

  6. 46 CFR 153.556 - Special requirements for sulfuric acid and oleum.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...false Special requirements for sulfuric acid and oleum. 153.556 Section 153...556 Special requirements for sulfuric acid and oleum. (a) Except as prescribed...containment systems carrying sulfuric acid, oleum, or contaminated sulfuric...

  7. 46 CFR 153.556 - Special requirements for sulfuric acid and oleum.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...false Special requirements for sulfuric acid and oleum. 153.556 Section 153...556 Special requirements for sulfuric acid and oleum. (a) Except as prescribed...containment systems carrying sulfuric acid, oleum, or contaminated sulfuric...

  8. 46 CFR 153.556 - Special requirements for sulfuric acid and oleum.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false Special requirements for sulfuric acid and oleum. 153.556 Section 153...556 Special requirements for sulfuric acid and oleum. (a) Except as prescribed...containment systems carrying sulfuric acid, oleum, or contaminated sulfuric...

  9. 46 CFR 153.556 - Special requirements for sulfuric acid and oleum.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...false Special requirements for sulfuric acid and oleum. 153.556 Section 153...556 Special requirements for sulfuric acid and oleum. (a) Except as prescribed...containment systems carrying sulfuric acid, oleum, or contaminated sulfuric...

  10. Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols

    E-print Network

    Robock, Alan

    aerosols can potentially result in an increase in acid deposition. [4] Acid rain has been studiedSulfuric acid deposition from stratospheric geoengineering with sulfate aerosols Ben Kravitz,1 Alan limit of hydration of all sulfate aerosols into sulfuric acid. For annual injection of 5 Tg of SO2

  11. Rheological characterization of dilute acid pretreated softwood.

    PubMed

    Wiman, Magnus; Palmqvist, Benny; Tornberg, Eva; Lidén, Gunnar

    2011-05-01

    Large-scale bioethanol production from lignocellulosic biomass will require high solids loading in the enzymatic hydrolysis step. However, slurries of pretreated lignocelluloses are complex fluids due to the fibrous nature, especially at high concentrations of water insoluble solids (WIS). A prerequisite for dealing with transport issues and for developing efficient full-scale processes is a fundamental understanding of the flow properties of pretreated lignocellulose. A comprehensive rheological characterization of dilute acid pretreated spruce has been carried out in this study, accounting for the effects of WIS concentration, particle size distribution (PSD), and the degree of enzymatic hydrolysis. The rheology of pretreated spruce slurries was found to be strongly dependent on the WIS concentration. The storage modulus (G'(LVR)) and yield stress showed typical power-law dependencies on volume fraction and WIS content. Milling of the pretreated material resulted in significantly higher yield stress and viscosity, likely due to narrower PSD, which suggests that the strength of the network of the coarsest fibers determines the rheology of these materials to a large extent. During enzymatic hydrolysis, yield stress and viscosity decreased dramatically, partly due to decreasing WIS content, but possibly also due to changes in fiber properties such as the chemical composition. PMID:21449021

  12. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...colorless, oily liquid. It is prepared by reacting sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the...

  13. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...colorless, oily liquid. It is prepared by reacting sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the...

  14. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...colorless, oily liquid. It is prepared by reacting sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the...

  15. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...colorless, oily liquid. It is prepared by reacting sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the...

  16. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...colorless, oily liquid. It is prepared by reacting sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the...

  17. Heterogeneous Interactions of Acetaldehyde and Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Michelsen, R. R.; Ashbourn, S. F. M.; Iraci, L. T.

    2004-01-01

    The uptake of acetaldehyde [CH3CHO] by aqueous sulfuric acid has been studied via Knudsen cell experiments over ranges of temperature (210-250 K) and acid concentration (40-80 wt. %) representative of the upper troposphere. The Henry's law constants for acetaldehyde calculated from these data range from 6 x 10(exp 2) M/atm for 40 wt. % H2SO4 at 228 K to 2 x 10(exp 5) M/atm for 80 wt. % H2SO4 at 212 K. In some instances, acetaldehyde uptake exhibits apparent steady-state loss. The possible sources of this behavior, including polymerization, will be explored. Furthermore, the implications for heterogeneous reactions of aldehydes in sulfate aerosols in the upper troposphere will be discussed.

  18. Total sulfate vs. sulfuric acid monomer concenterations in nucleation studies

    NASA Astrophysics Data System (ADS)

    Neitola, K.; Brus, D.; Makkonen, U.; Sipilä, M.; Mauldin, R. L., III; Sarnela, N.; Jokinen, T.; Lihavainen, H.; Kulmala, M.

    2015-03-01

    Sulfuric acid is known to be a key component for atmospheric nucleation. Precise determination of sulfuric-acid concentration is a crucial factor for prediction of nucleation rates and subsequent growth. In our study, we have noticed a substantial discrepancy between sulfuric-acid monomer concentrations and total-sulfate concentrations measured from the same source of sulfuric-acid vapor. The discrepancy of about 1-2 orders of magnitude was found with similar particle-formation rates. To investigate this discrepancy, and its effect on nucleation, a method of thermally controlled saturator filled with pure sulfuric acid (97% wt.) for production of sulfuric-acid vapor is applied and rigorously tested. The saturator provided an independent vapor-production method, compared to our previous method of the furnace (Brus et al., 2010, 2011), to find out if the discrepancy is caused by the production method itself. The saturator was used in a H2SO4-H2O nucleation experiment, using a laminar flow tube to check reproducibility of the nucleation results with the saturator method, compared to the furnace. Two independent methods of mass spectrometry and online ion chromatography were used for detecting sulfuric-acid or sulfate concentrations. Measured sulfuric-acid or total-sulfate concentrations are compared to theoretical predictions calculated using vapor pressure and a mixing law. The calculated prediction of sulfuric-acid concentrations agrees very well with the measured values when total sulfate is considered. Sulfuric-acid monomer concentration was found to be about 2 orders of magnitude lower than theoretical predictions, but with a temperature dependency similar to the predictions and the results obtained with the ion-chromatograph method. Formation rates are reproducible when compared to our previous results with both sulfuric-acid or total-sulfate detection and sulfuric-acid production methods separately, removing any doubts that the vapor-production method would cause the discrepancy. Possible reasons for the discrepancy are discussed and some suggestions include that the missing sulfuric acid is in clusters, formed with contaminants found in most laboratory experiments. One-to-two-order-of-magnitude higher sulfuric-acid concentrations (measured as total sulfate in this study) would contribute to a higher fraction of particle growth rate than assumed from the measurements by mass spectrometers (i.e. sulfuric-acid monomer). However, the observed growth rates by sulfate-containing vapor in this study does not directly imply a similar situation in the field, where sources of sulfate are much more diverse.

  19. Determination of trace sulfur in biodiesel and diesel standard reference materials by isotope dilution sector field inductively coupled plasma mass spectrometry.

    PubMed

    Amais, Renata S; Long, Stephen E; Nóbrega, Joaquim A; Christopher, Steven J

    2014-01-01

    A method is described for quantification of sulfur at low concentrations on the order of mgkg(-1) in biodiesel and diesel fuels using isotope dilution and sector field inductively coupled plasma mass spectrometry (ID-SF-ICP-MS). Closed vessel microwave-assisted digestion was employed using a diluted nitric acid and hydrogen peroxide decomposition medium to reduce sample dilution volumes. Medium resolution mode was employed to eliminate isobaric interferences at (32)S and (34)S related to polyatomic phosphorus and oxygen species, and sulfur hydride species. The method outlined yielded respective limits of detection (LOD) and limits of quantification (LOQ) of 0.7 mg kg(-1) S and 2.5 mg kg(-1) S (in the sample). The LOD was constrained by instrument background counts at (32)S but was sufficient to facilitate value assignment of total S mass fraction in NIST SRM 2723b Sulfur in Diesel Fuel Oil at 9.06±0.13 mg kg(-1). No statistically significant difference at a 95% confidence level was observed between the measured and certified values for certified reference materials NIST SRM 2773 B100 Biodiesel (Animal-Based), CENAM DRM 272b and NIST SRM 2723a Sulfur in Diesel Fuel Oil, validating method accuracy. PMID:24331043

  20. Solubility of HCL in sulfuric acid at stratospheric temperatures

    SciTech Connect

    Williams, L.R.; Golden, D.M.

    1993-10-22

    The solubility of HCl in sulfuric acid was measured using a Knudsen cell technique. Effective Henry's law constants are reported for sulfuric acid concentrations between 50 and 60 weight percent and for temperatures between 220 and 230 K. The measured values indicate that very little HCl will be dissolved in the stratospheric sulfate aerosol particles.

  1. COMPARISON OF AUTOMATED AND MANUAL SULFURIC ACID SAMPLING SYSTEMS

    EPA Science Inventory

    The purpose of this program was to evaluate the performance of three sulfuric acid vapor sampling systems consisting of (1) a commercially available continuous monitor (SSL) manufactured by Severn Science Limited of Great Britain, (2) an automated prototype sulfuric acid mist mon...

  2. RESISTANCE OF FLY ASH BASED GEOPOLYMER MORTARS IN SULFURIC ACID

    Microsoft Academic Search

    Suresh Thokchom; Partha Ghosh; Somnath Ghosh

    The present paper reports the experimental results of a study conducted to assess the resistance of fly ash based Geopolymer mortar specimens in sulfuric acid. The program consisted immersion of geopolymer mortar samples having percentage Na2O ranging from 5% to 8% of fly ash in a 10% Sulfuric acid solution up to a period of 18 weeks and evaluation of

  3. Solubility of HCL in sulfuric acid at stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Golden, David M.

    1993-01-01

    The solubility of HCl in sulfuric acid was measured using a Knudsen cell technique. Effective Henry's law constants are reported for sulfuric acid concentrations between 50 and 60 weight percent and for temperatures between 220 and 230 K. The measured values indicate that very little HCl will be dissolved in the stratospheric sulfate aerosol particles.

  4. Pressure leaching of synthetic zinc silicate in sulfuric acid medium

    Microsoft Academic Search

    Shanming He; Jikun Wang; Jiangfeng Yan

    2011-01-01

    The pressure leaching of synthetic zinc silicate is studied in the present paper. Five key parameters were explored, namely, sulfuric acid concentration, the final pH of leaching pulp, leaching temperature, water content and iron addition. The experimental results obtained show that sulfuric acid concentration, the final pH, iron addition, water content and leaching temperature have significant effect on the leaching

  5. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...sulfuric acid ester, substituted amine salt. 721.7770 Section 721.7770 ...sulfuric acid ester, substituted amine salt. (a) Chemical substance and significant...sulfuric acid ester, substituted amine salt (PMN P-92-396) is subject to...

  6. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...sulfuric acid ester, substituted amine salt. 721.7770 Section 721.7770 ...sulfuric acid ester, substituted amine salt. (a) Chemical substance and significant...sulfuric acid ester, substituted amine salt (PMN P-92-396) is subject to...

  7. Determining the sulfuric acid fog concentration in coke oven gas

    Microsoft Academic Search

    S. I. Zinkovskaya; E. L. Okhrimenko; L. V. Sobko

    1982-01-01

    A volumetric method for the analysis of sulfuric acid aerosols at levels of acid greater (25-40 g\\/mĀ³) than those (1 g\\/mĀ³) analyzable by current methods is described. Coke oven gas after acid scrubbing and electrofiltration is passed through a Schott filter (pressure drop 100 mm Hg), the sulfuric acid aerosol being condensed on the filter which is washed with water

  8. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

    NASA Technical Reports Server (NTRS)

    Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

    1990-01-01

    The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

  9. Leaching kinetics of Panzhihua ilmenite in sulfuric acid

    Microsoft Academic Search

    Bin Liang; Chun Li; Chenggang Zhang; Yongkui Zhang

    2005-01-01

    About 90% of the titanium deposits in China are located in the Panzhihua area. The dissolution of Panzhihua ilmenite in sulfuric acid was investigated. The kinetic experiments were carried out with an initial acid\\/ilmenite (wt.) ratio of 500:15, a sulfuric acid concentration of 15.4 M and temperatures from 100 to 198 °C. The results show that the leaching kinetics can

  10. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  11. Vapor pressures in the ternary system water-nitric acid-sulfuric acid and low temperatures

    Microsoft Academic Search

    A. Jaecker-Voirol; J. L. Ponche; P. Mirabel

    1990-01-01

    The partial vapor pressures over liquid or supercooled solutions of water and nitric acid and of water and sulfuric acid are calculated for temperatures below 0 C. From these results, the partial vapor pressures over the tenary system water-nitric acid-sulfuric acid (liquid or supercooled) have been estimated and compared with the available experimental data of Vandoni (1944) at 0 C.

  12. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  13. Determining the sulfuric acid fog concentration in coke oven gas

    SciTech Connect

    Zin'kovskaya, S.I.; Okhrimenko, E.L.; Sobko, L.V.

    1982-11-06

    A volumetric method for the analysis of sulfuric acid aerosols at levels of acid greater (25-40 g/m/sup 3/) than those (1 g/m/sup 3/) analyzable by current methods is described. Coke oven gas after acid scrubbing and electrofiltration is passed through a Schott filter (pressure drop 100 mm Hg), the sulfuric acid aerosol being condensed on the filter which is washed with water and the washings filtered with NaOH (0.01 N after electrofilter, 1.0 N after the acid towers) to methyl orange end point. The error is +/- 2%.

  14. Structure and saccharification of rice straw pretreated with sulfur trioxide micro-thermal explosion collaborative dilutes alkali.

    PubMed

    Yao, Ri-sheng; Hu, Hua-jia; Deng, Sheng-song; Wang, Huai; Zhu, Hui-xia

    2011-05-01

    In this paper, a sulfur trioxide collaborative dilutes alkali method has been developed to pre-treat rice straw and it has been studied that the pre-treated rice straw structure affected the saccharification of the rice straw hydrolyzed by cellulose enzymatic hydrolysis. The results show that the reaction of the sulfur trioxide with rice straw resulted in the internal micro-thermal explosion, and the saccharification rate was 91% based on the pretreated rice straw with sulfur trioxide for 4h following 1% w/v NaOH treatment for 7h at 50°C. PMID:21392977

  15. 40 CFR 417.140 - Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids subcategory. 417.140 Section 417.140 Protection...POINT SOURCE CATEGORY Neutralization of Sulfuric Acid Esters and Sulfonic Acids Subcategory §...

  16. 40 CFR 417.140 - Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids subcategory. 417.140 Section 417.140 Protection...POINT SOURCE CATEGORY Neutralization of Sulfuric Acid Esters and Sulfonic Acids Subcategory §...

  17. 40 CFR 417.140 - Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids subcategory. 417.140 Section 417.140 Protection...POINT SOURCE CATEGORY Neutralization of Sulfuric Acid Esters and Sulfonic Acids Subcategory §...

  18. 40 CFR 417.140 - Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids subcategory. 417.140 Section 417.140 Protection...POINT SOURCE CATEGORY Neutralization of Sulfuric Acid Esters and Sulfonic Acids Subcategory §...

  19. 40 CFR 417.140 - Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Applicability; description of the neutralization of sulfuric acid esters and sulfonic acids subcategory. 417.140 Section 417.140 Protection...POINT SOURCE CATEGORY Neutralization of Sulfuric Acid Esters and Sulfonic Acids Subcategory §...

  20. Gas dilution system results and application to acid rain utilities

    SciTech Connect

    Jolley-Souders, K.; Geib, R. [Matheson Gas Products, Montgomeryville, PA (United States); Dunn, C. [Environics, Inc., Tolland, CT (United States)

    1997-12-31

    In 1997, the United States EPA will remove restrictions preventing acid rain utilities from using gas dilution systems for calibration or linearity studies for continuous emissions monitoring, Test Method 205 in 40CFR51 requires that a gas dilution system must produce calibration gases whose measured values are within {+-}2% of predicted values. This paper presents the evaluation of the Environics/CalMat 2020 Dilution System for use in calibration studies. Internal studies show that concentrations generated by this unit are within {+-}0.5% of predicted values. Studies are being conducted by several acid rain utilities to evaluate the Environics/CalMat system using single minor component calibration standards. In addition, an internally generated study is being performed to demonstrate the system`s accuracy using a multi-component gas mixture. Data from these tests will be presented in the final version of the paper.

  1. EXTRACTION OF RARE EARTHS AND THORIUM FROM SULFURIC ACID BY DIISOBUTYLPHOSPHORIC ACID

    Microsoft Academic Search

    Z. A. Sheka; E. I. Sinyavskaya

    1963-01-01

    Solvent extraction of Ce(III), Er, Ho, Gd, La, Nd, Sm, Tb, Y, Yb and Th ; from sulfuric acid by a 0.148 molar solution of diisobutylphosphoric acid in ; kerosene was analyzed. It was found that each of the rare earths and thorium are ; fully separated at a certain concentration of sulfuric acid. Extractability of ; rare earth and

  2. Dilute acid hydrolysis of paper birch: kinetics studies of xylan and acetyl-group hydrolysis.

    PubMed

    Maloney, M T; Chapman, T W; Baker, A J

    1985-03-01

    Batch hydrolysis kinetics of paper birch (Betula papyrifera) xylan and its associated acetyl groups in dilute sulfuric acid have been measured for acid concentrations of between 0.04 and 0.18M and temperatures of between 100 and 170 degrees C. Only 5% of the cellulose was hydrolyzed for up to 85% xylan removal. Rate data were correlated well by a parallel reaction model based on the existence of reactive and resistant xylan portions. The resulting rate equation predicts the experimental xylan concentrations in the residue to within 10%. Hydrolysis of xylan-associated acetyl groups was found to occur at the same rate as that of xylan, except at 100 degrees C, where acetyl is released preferentially. No effect of acid concentration on the rate of acetyl removal relative to that of xylan was evident. PMID:18553680

  3. Factors to consider for using zirconium in sulfuric acid services

    SciTech Connect

    Fitzgerald, B.J. [Exxon Chemical Co., Baytown, TX (United States); Webber, R.G. [Exxon Chemical Co., Baton Rouge, LA (United States); Frechem, B.S. [Rohm and Haas Co., Spring House, PA (United States); Briegel, K.F. [Rohm and Haas Texas Co., Deer Park, TX (United States); Yau, T.L. [Teledyne Wah Chang, Albany, OR (United States)

    1995-10-01

    Zirconium is a pivotal material often specified for process equipment that handles highly corrosive sulfuric acid solutions. Because of the complicated nature of sulfuric acid, several factors should be addressed to ensure the durability of zirconium equipment. These factors include acid concentration, temperature, pressure, impurity, stress, crevices, welding, and surfaces condition. Depending on the situation, certain potential hazards to zirconium equipment can be prevented by applying control measures such as heat treatment, proper design and operating, inhibitor, surface conditioning and/or shot peening.

  4. MOLECULAR SIEVE TESTS FOR CONTROL OF SULFURIC ACID PLANT EMISSIONS

    EPA Science Inventory

    The report gives results of tests of a molecular sieve control system for sulfuric acid plant tail gas. The PuraSiv S uses molecular sieve adsorbent material that releases SO2 when heat is applied. The SO2 is recycled for an additional 2-3% production of acid. The report evaluate...

  5. Potential heat exchange fluids for use in sulfuric acid vaporizers

    Microsoft Academic Search

    D. D. Lawson; G. R. Petersen

    1979-01-01

    A series of perhalocarbons are proposed as candidate heat exchange fluids for service in thermochemical cycles for hydrogen production that involve direct contact of the fluid with sulfuric acid and vaporization of the acid. The required chemical and physical criteria of the liquids are described and the results of some preliminary high temperature test data are presented.

  6. CAPSULE REPORT: RECOVERY OF SPENT SULFURIC ACID FROM STEEL PICKLING OPERATIONS

    EPA Science Inventory

    This report provides small manufacturers using sulfuric acid pickling with the technical and economic information necessary to select the most appropriate treatment technologies for recovering or treating their sulfuric acid. reatment alternatives include recovery of the acid, ne...

  7. Kinetic study of empty fruit bunch using hot liquid water and dilute acid.

    PubMed

    Kim, Jun Seok; Choi, Won Il; Kang, Minsu; Park, Ji Yeon; Lee, Jin-Suk

    2012-07-01

    Empty fruit bunch (EFB), a residual product of the palm plantation, is an attractive biomass for biorefinery. As xylan is susceptible to high temperature pretreatment, it is important to setup a proper pretreatment condition to maximize the sugar recovery from EFB. Kinetic parameters of mathematical models were obtained in order to predict the concentration of xylose, glucose, furfural, and acetic acid in the hydrolysate and to find production conditions of xylose. We investigated the kinetics of hot liquid water and dilute sulfuric acid hydrolysis over a 40-min period using a self-designed setup by measuring the concentrations of released sugars (xylose, glucose) and degradation products (acetic acid and furfural). The reaction was performed within the range 160?180 °C, under reaction conditions of various concentration of sulfuric acid (0.1?0.2%) and 1:7 solid-liquid ratio in a batch reactor. The kinetic constants can be expressed by the Arrhenius equation with the activation energy for the hydrolysis of sugar and decomposition of sugar. The activation energy of xylose was determined to be 136.2187 kJ mol(-1). PMID:22238014

  8. Dilute-acid hydrolysis of sugarcane bagasse at varying conditions

    Microsoft Academic Search

    Markus Neureiter; Herbert Danner; Christiane Thomasser; Bamusi Saidi; Rudolf Braun

    2002-01-01

    Sugarcane bagasse, a byproduct of the cane sugar industry, is an abundant source of hemicellulose that could be hydrolyzed\\u000a to yield a fermentation feedstock for the production of fuel ethanol and chemicals. The effects of sulfuric acid concentration,\\u000a temperature, time, and dry matter concentration on hemicellulose hydrolysis were studied with a 20-L batch hydrolysis reactor\\u000a using a statistical experimental design.

  9. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2000-12-01

    This document summarizes progress on the Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2000 through September 30, 2000. 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 will also be determined, as will the removal of arsenic, a known poison for NOX selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), First Energy Corporation, and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. This is the second reporting period for the subject Cooperative Agreement. During this period, the first of four short-term sorbent injection tests were conducted at the First Energy Bruce Mansfield Plant. This test determined the effectiveness of dolomite injection through out-of-service burners as a means of controlling sulfuric acid emissions from this unit. The tests showed that dolomite injection could achieve up to 95% sulfuric acid removal. Balance of plant impacts on furnace slagging and fouling, air heater fouling, ash loss-on-ignition, and the flue gas desulfurization system were also determined. These results are presented and discussed in this report.

  10. Dielectric study on dynamics and conformation of poly( d, l-lactic acid) in dilute and semi-dilute solutions

    Microsoft Academic Search

    Jindong Ren; Osamu Urakawa; Keiichiro Adachi

    2003-01-01

    Fractionated samples of d,l-poly(lactic acid) (PLA) were prepared and the dielectric normal mode relaxation was studied for dilute and semi-dilute solutions of the PLA in a good solvent benzene. Results indicate that in the dilute regime the normal mode relaxation time is proportional to [?]Mw in agreement with the Rouse–Zimm theory, where [?] and Mw denote the intrinsic viscosity and

  11. Breakdown of Cell Wall Nanostructure in Dilute Acid Pretreated Biomass

    SciTech Connect

    Pingali, Sai Venkatesh [ORNL; Urban, Volker S [ORNL; Heller, William T [ORNL; McGaughey, Joseph [ORNL; O'Neill, Hugh Michael [ORNL; Foston, Marcus B [ORNL; Myles, Dean A A [ORNL; Ragauskas, Arthur J [ORNL; Evans, Barbara R [ORNL

    2010-01-01

    The generation of bioethanol from lignocellulosic biomass holds great promise for renewable and clean energy production. A better understanding of the complex mechanisms of lignocellulose breakdown during various pretreatment methods is needed to realize this potential in a cost and energy efficient way. Here, we use small-angle neutron scattering (SANS) to characterize morphological changes in switchgrass lignocellulose across molecular to sub-micron length scales resulting from the industrially-relevant dilute acid pretreatment method. Our results demonstrate that dilute acid pretreatment increases the cross-sectional radius of the crystalline cellulose fibril. This change is accompanied by removal of hemicellulose and the formation of Rg ~ 135 lignin aggregates. The structural signature of smooth cell wall surfaces is observed at length scales larger than 1000 , and it remains remarkably invariable during pretreatment. This study elucidates the interplay of the different biomolecular components in the break down process of switchgrass by dilute acid pretreatment. The results are important for the development of efficient strategies of biomass to biofuel conversion.

  12. Breakdown of cell wall nanostructure in dilute acid pretreated biomass.

    PubMed

    Pingali, Sai Venkatesh; Urban, Volker S; Heller, William T; McGaughey, Joseph; O'Neill, Hugh; Foston, Marcus; Myles, Dean A; Ragauskas, Arthur; Evans, Barbara R

    2010-09-13

    The generation of bioethanol from lignocellulosic biomass holds great promise for renewable and clean energy production. A better understanding of the complex mechanisms of lignocellulose breakdown during various pretreatment methods is needed to realize this potential in a cost and energy efficient way. Here we use small-angle neutron scattering (SANS) to characterize morphological changes in switchgrass lignocellulose across molecular to submicrometer length scales resulting from the industrially relevant dilute acid pretreatment method. Our results demonstrate that dilute acid pretreatment increases the cross-sectional radius of the crystalline cellulose fibril. This change is accompanied by removal of hemicellulose and the formation of R(g) ? 135 A lignin aggregates. The structural signature of smooth cell wall surfaces is observed at length scales larger than 1000 A, and it remains remarkably invariable during pretreatment. This study elucidates the interplay of the different biomolecular components in the breakdown process of switchgrass by dilute acid pretreatment. The results are important for the development of efficient strategies of biomass to biofuel conversion. PMID:20726544

  13. A tunable diode laser stack monitor for sulfuric acid vapor

    Microsoft Academic Search

    E. F. Person; A. W. Mantz

    1979-01-01

    A field prototype instrument for continuous in situ monitoring of sulfuric acid vapor in industrial smoke stacks was developed. The method of detection is dual wavelength differential absorption in the infrared. Two tunable diode lasers are locked to two specific frequencies that provide analytical and background absorption information. The difference between the analytical and background absorption yields the net absorption

  14. EPA'S CATALYST RESEARCH PROGRAM: ENVIRONMENTAL IMPACT OF SULFURIC ACID EMISSIONS

    EPA Science Inventory

    A sulfuric acid review conference sponsored by EPA's automotive Catalyst Research Program was held recently at Hendersonville, NC, for researchers whose work is funded by EPA. Emissions characterization research indicated that in-use catalyst-equipped vehicles emit low levels of ...

  15. ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

    EPA Science Inventory

    The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

  16. Atmospheric Environment 40 (2006) 68636878 Acid-catalyzed reactions of hexanal on sulfuric acid particles

    E-print Network

    Elrod, Matthew J.

    2006-01-01

    Atmospheric Environment 40 (2006) 6863­6878 Acid-catalyzed reactions of hexanal on sulfuric acid are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe

  17. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2000-12-01

    A test program is being sponsored by the US Department of Energy (DOE), EPRI, FirstEnergy, and TVA to investigate furnace injection of alkaline sorbents as a means of reducing sulfuric acid concentrations in the flue gas from coal-fired boilers. This test program is being conducted at the FirstEnergy Bruce Mansfield Plant (BMP), although later testing will be conducted at a TVA plant. A sorbent injection test was conducted the week of April 18, 2000. The test was the first of several short-term (one- to two-week duration) tests to investigate the effectiveness of various alkaline sorbents for sulfuric acid control and the effects of these sorbents on boiler equipment performance. This first short-term test investigated the effect of injecting dry dolomite powder (CaCO{sub 3} {center_dot} MgCO{sub 3}), a mineral similar to limestone, into the furnace of Unit 2. During the test program, various analytical techniques were used to assess the effects of sorbent injection. These primarily included sampling with the controlled condensation system (CCS) for determining flue gas SO{sub 3} content and an acid dew-point (ADP) meter for determining the sulfuric acid dew point (and, indirectly, the concentration of sulfuric acid) of the flue gas. EPA Reference Method 26a was used for determining hydrochloric acid (HCl) and hydrofluoric acid (HF), as well and chlorine (Cl{sub 2}) and fluorine (F{sub 2}) concentrations in the flue gas. Fly ash resistivity was measured using a Southern Research Institute (SRI) point-to-plane resistivity probe, and unburned carbon in fly ash was determined by loss on ignition (LOI). Coal samples were also collected and analyzed for a variety of parameters. Finally, visual observations were made of boiler furnace and convective pass surfaces prior to and during sorbent injection.

  18. Cellulase Accessibility of Dilute-Acid Pretreated Corn Stover

    SciTech Connect

    Jeoh, T.; Johnson, D. K.; Adney, W. S.; Himmel, M. E.

    2005-01-01

    The conclusions of this presentation are: (1) The dilute-acid pretreatment reduces xylan content in corn stover. This reduction in xylan content appears to render the substrate less recalcitrant. Below {approx}8%, xylan content is no longer the dominant factor in biomass recalcitrance. (2) Decreasing xylan content of corn stover also created more binding sites for Cel7A, but no strong correlation with actual xylan content. (3) We found no correlation between bound Cel7A concentration and lignin content. Maybe lignin is blocking the way for Cel7A? The contribution of lignin to biomass recalcitrance requires further investigation.

  19. Free energy barrier in the growth of sulfuric acid-ammonia and sulfuric acid-dimethylamine clusters

    NASA Astrophysics Data System (ADS)

    Olenius, T.; Kupiainen-Määttä, O.; Ortega, I. K.; Kurtén, T.; Vehkamäki, H.

    2013-08-01

    The first step in atmospheric new particle formation involves the aggregation of gas phase molecules into small molecular clusters that can grow by colliding with gas molecules and each other. In this work we used first principles quantum chemistry combined with a dynamic model to study the steady-state kinetics of sets of small clusters consisting of sulfuric acid and ammonia or sulfuric acid and dimethylamine molecules. Both sets were studied with and without electrically charged clusters. We show the main clustering pathways in the simulated systems together with the quantum chemical Gibbs free energies of formation of the growing clusters. In the sulfuric acid-ammonia system, the major growth pathways exhibit free energy barriers, whereas in the acid-dimethylamine system the growth occurs mainly via barrierless condensation. When ions are present, charged clusters contribute significantly to the growth in the acid-ammonia system. For dimethylamine the role of ions is minor, except at very low acid concentration, and the growing clusters are electrically neutral.

  20. Development of a stable isotope dilution assay for tenuazonic acid.

    PubMed

    Asam, Stefan; Liu, Yang; Konitzer, Katharina; Rychlik, Michael

    2011-04-13

    A stable isotope dilution assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [(13)C(6),(15)N]-tenuazonic acid was synthesized from [(13)C(6),(15)N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [(13)C(6),(15)N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 ?g/kg and a limit of quantitation of 0.3 ?g/kg. Recovery was close to 100% in the range of 3-300 ?g/kg. Determination of tenuazonic acid in two samples of different tomato ketchups (naturally contaminated) was achieved with a coefficient of variation of 2.3% and 4.7%. Different tomato products (n = 16) were analyzed for their content of tenuazonic acid using the developed SIDA. Values were between 15 and 195 ?g/kg (tomato ketchup, n = 9), 363 and 909 ?g/kg (tomato paste, n = 2), and 8 and 247 ?g/kg (pureed tomatoes and comparable products, n = 5). PMID:21370870

  1. Metabolism of sulfur amino acids in Saccharomyces cerevisiae.

    PubMed Central

    Thomas, D; Surdin-Kerjan, Y

    1997-01-01

    Sulfur amino acid biosynthesis in Saccharomyces cerevisiae involves a large number of enzymes required for the de novo biosynthesis of methionine and cysteine and the recycling of organic sulfur metabolites. This review summarizes the details of these processes and analyzes the molecular data which have been acquired in this metabolic area. Sulfur biochemistry appears not to be unique through terrestrial life, and S. cerevisiae is one of the species of sulfate-assimilatory organisms possessing a larger set of enzymes for sulfur metabolism. The review also deals with several enzyme deficiencies that lead to a nutritional requirement for organic sulfur, although they do not correspond to defects within the biosynthetic pathway. In S. cerevisiae, the sulfur amino acid biosynthetic pathway is tightly controlled: in response to an increase in the amount of intracellular S-adenosylmethionine (AdoMet), transcription of the coregulated genes is turned off. The second part of the review is devoted to the molecular mechanisms underlying this regulation. The coordinated response to AdoMet requires two cis-acting promoter elements. One centers on the sequence TCACGTG, which also constitutes a component of all S. cerevisiae centromeres. Situated upstream of the sulfur genes, this element is the binding site of a transcription activation complex consisting of a basic helix-loop-helix factor, Cbf1p, and two basic leucine zipper factors, Met4p and Met28p. Molecular studies have unraveled the specific functions for each subunit of the Cbf1p-Met4p-Met28p complex as well as the modalities of its assembly on the DNA. The Cbf1p-Met4p-Met28p complex contains only one transcription activation module, the Met4p subunit. Detailed mutational analysis of Met4p has elucidated its functional organization. In addition to its activation and bZIP domains, Met4p contains two regulatory domains, called the inhibitory region and the auxiliary domain. When the level of intracellular AdoMet increases, the transcription activation function of Met4 is prevented by Met30p, which binds to the Met4 inhibitory region. In addition to the Cbf1p-Met4p-Met28p complex, transcriptional regulation involves two zinc finger-containing proteins, Met31p and Met32p. The AdoMet-mediated control of the sulfur amino acid pathway illustrates the molecular strategies used by eucaryotic cells to couple gene expression to metabolic changes. PMID:9409150

  2. Uptake and Dissolution of Gaseous Ethanol in Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Michelsen, Rebecca R.; Staton, Sarah J. R.; Iraci, Laura T.

    2006-01-01

    The solubility of gas-phase ethanol (ethyl alcohol, CH3CH2OH, EtOH) in aqueous sulfuric acid solutions was measured in a Knudsen cell reactor over ranges of temperature (209-237 K) and acid composition (39-76 wt % H2SO4). Ethanol is very soluble under these conditions: effective Henry's law coefficients, H*, range from 4 x 10(exp 4) M/atm in the 227 K, 39 wt % acid to greater than 10(exp 7) M/atm in the 76 wt % acid. In 76 wt % sulfuric acid, ethanol solubility exceeds that which can be precisely determined using the Knudsen cell technique but falls in the range of 10(exp 7)-10(exp 10) M/atm. The equilibrium concentration of ethanol in upper tropospheric/lower stratospheric (UT/LS) sulfate particles is calculated from these measurements and compared to other small oxygenated organic compounds. Even if ethanol is a minor component in the gas phase, it may be a major constituent of the organic fraction in the particle phase. No evidence for the formation of ethyl hydrogen sulfate was found under our experimental conditions. While the protonation of ethanol does augment solubility at higher acidity, the primary reason H* increases with acidity is an increase in the solubility of molecular (i.e., neutral) ethanol.

  3. A comparative study of leaching kinetics of limonitic laterite and synthetic iron oxides in sulfuric acid containing sulfur dioxide

    Microsoft Academic Search

    G Senanayake; G. K Das

    2004-01-01

    Limonitic laterite ore of particle size 90–125 ?m containing goethite, magnetite and hematite was leached for 6 h at a pulp density of 10% (wt\\/vol) in sulfuric acid in the absence or presence of sulfur dioxide at atmospheric pressure and 90 °C in a glass reactor vessel. The sulfur dioxide flow rate was kept at 0.6 L min?1 L?1 of

  4. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2001-11-06

    This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2001 through September 30, 2001. 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, and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. During the current period, American Electric Power (AEP) joined the project as an additional co-funder and as a provider of a host site for testing. This is the fourth reporting period for the subject Cooperative Agreement. During this 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 Station. These 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 Station), and a byproduct magnesium hydroxide slurry (both Gavin Station and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70 to 75% sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Station, 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. Balance of plant impacts, primarily on the ESP particulate control device, were also determined during both tests. These results are presented and discussed in this report.

  5. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2002-04-29

    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 previous semi-annual technical progress report (April 1, 2001 through September 30, 2001). During the current reporting period, additional balance of plant impact information was determined for one of the two tests. These additional balance-of-plant results are presented and discussed in this report. There was no other technical progress to report, because all planned testing as part of this project has been completed.

  6. Thermal Regeneration of Sulfuric Acid Hydrates after Irradiation

    NASA Technical Reports Server (NTRS)

    Loeffler, Mark J.; Hudson, Reggie L.

    2012-01-01

    In an attempt to more completely understand the surface chemistry of the jovian icy satellites, we have investigated the effect of heating on two irradiated crystalline sulfuric acid hydrates, H2SO4 4H2O and H2SO4 H2O. At temperatures relevant to Europa and the warmer jovian satellites, post-irradiation heating recrystallized the amorphized samples and increased the intensities of the remaining hydrate's infrared absorptions. This thermal regeneration of the original hydrates was nearly 100% efficient, indicating that over geological times, thermally-induced phase transitions enhanced by temperature fluctuations will reform a large fraction of crystalline hydrated sulfuric acid that is destroyed by radiation processing. The work described is the first demonstration of the competition between radiation-induced amorphization and thermally-induced recrystallization in icy ionic solids relevant to the outer Solar System.

  7. Optimizing dilute-acid pretreatment of rapeseed straw for extraction of hemicellulose.

    PubMed

    Jeong, Tae-Su; Um, Byung-Hwan; Kim, Jun-Seok; Oh, Kyeong-Keun

    2010-05-01

    Biological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars prior to fermentation. Hydrolysis can be performed enzymatically or with mineral acids. In this study, dilute sulfuric acid was used as a catalyst for the pretreatment of rapeseed straw. The purpose of this study is to optimize the pretreatment process in a 15-mL bomb tube reactor and investigate the effects of the acid concentration, temperature, and reaction time. These parameters influence hemicellulose removal and production of sugars (xylose, glucose, and arabinose) in the hydrolyzate as well as the formation of by-products (furfural, 5-hydroxymethylfurfural, and acetic acid). Statistical analysis was based on a model composition corresponding to a 3(3) orthogonal factorial design and employed the response surface methodology to optimize the pretreatment conditions, aiming to attain maximum xylan, mannan, and galactan (XMG) extraction from hemicellulose of rapeseed straw. The obtained optimum conditions were: H2SO4 concentration of 1.76% and temperature of 152.6 degrees C with a reaction time of 21 min. Under these optimal conditions, 85.5% of the total sugar was recovered after acid hydrolysis (78.9% XMG and 6.6% glucan). The hydrolyzate contained 1.60 g/L glucose, 0.61 g/L arabinose, 10.49 g/L xylose, mannose, and galactose, 0.39 g/L cellobiose, 0.94 g/L fructose, 0.02 g/L 1,6-anhydro-glucose, 1.17 g/L formic acid, 2.94 g/L acetic acid, 0.04 g/L levulinic acid, 0.04 g/L 5-hydroxymethylfurfural, and 0.98 g/L furfural. PMID:20087686

  8. EFFECTS OF SULFURIC ACID MIST EXPOSURE ON PULMONARY FUNCTION

    EPA Science Inventory

    Effects of 2-hr exposure to sulfuric acid (H2SO4) on pulmonary functions in male nonsmokers were examined. Subjects were exposed to air and 233, 418 and 939 micrograms/cu m H2SO4 at 22C DB/55% RH or air and 314, 600 and 1107 micrograms/cu m H2SO4 at 35C DB/85% RH. Mass media diam...

  9. Burns caused by dilute hydrofluoric acid in the bleach.

    PubMed

    Fujimoto, Kazuhisa; Yasuhara, Naoaki; Kawarada, Harumichi; Kosaka, Sachiko; Kawana, Seiji

    2002-04-01

    Two male cleaning workers aged 62 (patient 1) and 28-(patient 2) presented with red, swollen, aching hands and fingers. At the first interview, the fingers of the right hand of both patients were swollen from the proximal interphalangeal joint to the tip of the finger. The fingers were red and intensely painful. The bleach that both patients used contained 9.5% hydrofluoric acid, and therefore we diagnosed their symptoms as those of burns caused by this agent. We subcutaneously injected 8.5% calcium gluconate into the affected fingers and dressed them with gauze soaked in cooled 0.025% benzethonium chloride. The patients did not use gloves at work, neither of them knew that the cleaning fluid contained dilute hydrofluoric acid, and they were unaware of the danger of this agent. They had not received proper education about the care and handling of poisons and deleterious substances such as hydrofluoric acid. The doctors who had examined the patients in the emergency ward overlooked the possibility of hydrofluoric acid burns, although they suspected chemical burns and confirmed the trade name of the cleaning agent. In addition, although the patients presented with intense pain, no white areas of coagulation and blistering, or surrounding erythemas, which are characteristic symptoms of such burns, were evident. The component of the cleaning agent was described on the container label in very small print. Had the words "poison" and "hydrogen fluoride" been printed in large characters, the examining doctors in the emergency ward would probably not have overlooked the presence of hydrofluoric acid, and the patients would perhaps have been more careful when using it. Hydrofluoric acid can be easily obtained by anyone through the Internet, although general consumers could not obtain industrial quantities. Therefore, the number of burn patients who are not familiar with hydrofluoric acid may increase in the future. PMID:12068331

  10. DIURNAL AND SEASONAL PATTERNS OF PARTICULATE SULFUR AND SULFURIC ACID IN ST. LOUIS, JULY 1977-JUNE 1978

    EPA Science Inventory

    Continuous measurements of particulate sulfur and sulfuric acid were taken in St. Louis over a one year period using the in-situ thermal analysis-flame photometric method. These measurements were used to calculate average diurnal patterns for each quarter of the year, and also th...

  11. Sulfuric Acid Intercalated Graphite Oxide for Graphene Preparation

    PubMed Central

    Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

    2013-01-01

    Graphene has shown enormous potential for innovation in various research fields. The current chemical approaches based on exfoliation of graphite via graphite oxide (GO) are potential for large-scale synthesis of graphene but suffer from high cost, great operation difficulties, and serious waste discharge. We report a facile preparation of graphene by rapid reduction and expansion exfoliation of sulfuric acid intercalated graphite oxide (SIGO) at temperature just above 100°C in ambient atmosphere, noting that SIGO is easily available as the immediate oxidation descendent of graphite in sulfuric acid. The oxygenic and hydric groups in SIGO are mainly removed through dehydration as catalyzed by the intercalated sulfuric acid (ISA). The resultant consists of mostly single layer graphene sheets with a mean diameter of 1.07??m after dispersion in DMF. This SIGO process is reductant free, easy operation, low-energy, environmental friendly and generates graphene with low oxygen content, less defect and high conductivity. The provided synthesis route from graphite to graphene via SIGO is compact and readily scalable. PMID:24310650

  12. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721.9220...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). (a)...

  13. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721.9220...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). (a)...

  14. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721.9220...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). (a)...

  15. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721.9220...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). (a)...

  16. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721.9220...secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). (a)...

  17. Characterization of pilot-scale dilute acid pretreatment performance using deacetylated corn stover

    PubMed Central

    2014-01-01

    Background Dilute acid pretreatment is a promising process technology for the deconstruction of low-lignin lignocellulosic biomass, capable of producing high yields of hemicellulosic sugars and enhancing enzymatic yields of glucose as part of a biomass-to-biofuels process. However, while it has been extensively studied, most work has historically been conducted at relatively high acid concentrations of 1 - 4% (weight/weight). Reducing the effective acid loading in pretreatment has the potential to reduce chemical costs both for pretreatment and subsequent neutralization. Additionally, if acid loadings are sufficiently low, capital requirements associated with reactor construction may be significantly reduced due to the relaxation of requirements for exotic alloys. Despite these benefits, past efforts have had difficulty obtaining high process yields at low acid loadings without supplementation of additional unit operations, such as mechanical refining. Results Recently, we optimized the dilute acid pretreatment of deacetylated corn stover at low acid loadings in a 1-ton per day horizontal pretreatment reactor. This effort included more than 25 pilot-scale pretreatment experiments executed at reactor temperatures ranging from 150 – 170°C, residence times of 10 – 20 minutes and hydrolyzer sulfuric acid concentrations between 0.15 – 0.30% (weight/weight). In addition to characterizing the process yields achieved across the reaction space, the optimization identified a pretreatment reaction condition that achieved total xylose yields from pretreatment of 73.5%?±?1.5% with greater than 97% xylan component balance closure across a series of five runs at the same condition. Feedstock reactivity at this reaction condition after bench-scale high solids enzymatic hydrolysis was 77%, prior to the inclusion of any additional conversion that may occur during subsequent fermentation. Conclusions This study effectively characterized a range of pretreatment reaction conditions using deacetylated corn stover at low acid loadings and identified an optimum reaction condition was selected and used in a series of integrated pilot scale cellulosic ethanol production campaigns. Additionally, several issues exist to be considered in future pretreatment experiments in continuous reactor systems, including the formation of char within the reactor, as well as practical issues with feeding herbaceous feedstock into pressurized systems. PMID:24548527

  18. Binary nucleation in acid–water systems. II. Sulfuric acid–water and a comparison with methanesulfonic acid–water

    Microsoft Academic Search

    B. E. Wyslouzil; J. H. Seinfeld; R. C. Flagan; K. Okuyama

    1991-01-01

    This work presents a systematic investigation of binary nucleation rates for sulfuric acid and water and the effect of temperature on these rates at isothermal, subsaturated conditions. The results from nucleation rate measurements for the sulfuric acid (H2SO4) –water system are discussed and compared to those previously presented for methanesulfonic acid (MSA)–water [B. E. Wyslouzil, J. H. Seinfeld, R. C.

  19. Effects of acid rain and sulfur dioxide on marble dissolution

    SciTech Connect

    Schuster, P.F.; Reddy, M.M. (Geological Survey, Boulder, CO (United States)); Sherwood, S.I. (National Park Service, Washington, DC (United States))

    1994-01-01

    Acid precipitation and the dry deposition of sulfur dioxide (SO[sub 2]) accelerate damage to carbonate-stone monuments and building materials. This study identified and quantified environmental damage to a sample of Vermont marble during storms and their preceding dry periods. Results from field experiments indicated the deposition of SO[sub 2] gas to the stone surface during dry periods and a twofold increase in marble dissolution during coincident episodes of low rain rate and decreased rainfall pH. The study is widely applicable to the analysis of carbonate-stone damage at locations affected by acid rain and air pollution.

  20. Effects of acid rain and sulfur dioxide on marble dissolution

    USGS Publications Warehouse

    Schuster, Paul F.; Reddy, Michael M.; Sherwood, Susan I.

    1994-01-01

    Acid precipitation and the dry deposition of sulfur dioxide (SO2) accelerate damage to carbonate-stone monuments and building materials. This study identified and quantified environmental damage to a sample of Vermont marble during storms and their preceding dry periods. Results from field experiments indicated the deposition of SO2 gas to the stone surface during dry periods and a twofold increase in marble dissolution during coincident episodes of low rain rate and decreased rainfall pH. The study is widely applicable to the analysis of carbonate-stone damage at locations affected by acid rain and air pollution.

  1. Comparative study of SPORL and dilute-acid pretreatments of spruce for cellulosic ethanol production.

    PubMed

    Shuai, L; Yang, Q; Zhu, J Y; Lu, F C; Weimer, P J; Ralph, J; Pan, X J

    2010-05-01

    The performance of two pretreatment methods, sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) and dilute acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production at 180 degrees Celsius for 30 min with a sulfuric acid loading of 5% on oven-dry wood and a 5:1 liquor-to-wood ratio. SPORL was supplemented with 9% sodium sulfite (w/w of wood). The recoveries of total saccharides (hexoses and pentoses) were 87.9% (SPORL) and 56.7% (DA), while those of cellulose were 92.5% (SPORL) and 77.7% (DA). The total of known inhibitors (furfural, 5-hydroxymethylfurfural, and formic, acetic and levulinic acids) formed in SPORL were only 35% of those formed in DA pretreatment. SPORL pretreatment dissolved approximately 32% of the lignin as lignosulfonate, which is a potential high-value co-product. With an enzyme loading of 15 FPU (filter paper units) per gram of cellulose, the cellulose-to-glucose conversion yields were 91% at 24h for the SPORL substrate and 55% at 48 h for the DA substrate, respectively. PMID:20061141

  2. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2003-10-01

    This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2003 through September, 2003. 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 Group is the prime contractor. This is the eighth reporting period for the subject Cooperative Agreement. During previous reporting periods, 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 (both Gavin Plant 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 semi-annual Technical Progress Report for the time period April 1, 2001 through September 30, 2001. Additional balance of plant impact information for the two tests was reported in the Technical Progress Report for the time period October 1, 2001 through March 30, 2002. Additional information became available about the effects of byproduct magnesium hydroxide injection on SCR catalyst coupons during the long-term test at BMP, and those results were reported in the report for the time period April 1, 2002 through September 30, 2002. During the current period, process economic estimates were developed, comparing the costs of the furnace magnesium hydroxide slurry injection process tested as part of this project to a number of other candidate SO{sub 3}/sulfuric acid control technologies for coal-fired power plants. The results of this economic evaluation are included in this progress report.

  3. SULFURIC ACID REMOVAL PROCESS EVALUATION: SHORT-TERM RESULTS

    SciTech Connect

    Gary M. Blythe; Richard McMillan

    2002-02-04

    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. Sulfuric acid controls are becoming of increasing interest to utilities with coal-fired units for a number of reasons. Sulfuric acid is a Toxic Release Inventory species, a precursor to acid aerosol/condensable emissions, and can cause a variety of 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 SCR for NO{sub x} control on some coal-fired plants, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project is testing the effectiveness of furnace injection of four different calcium- and/or magnesium-based alkaline sorbents on full-scale utility boilers. These reagents have been tested during four one- to two-week tests conducted on two First Energy Bruce Mansfield Plant units. One of the sorbents tested was a magnesium hydroxide slurry produced from a wet flue gas desulfurization system waste stream, from a system that employs a Thiosorbic{reg_sign} Lime scrubbing process. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercial magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners, while the other three reagents were injected as slurries through air-atomizing nozzles into the front wall of upper furnace, either across from the nose of the furnace or across from the pendant superheater tubes. After completing the four one- to two-week tests, the most promising sorbents were selected for longer-term (approximately 25-day) full-scale tests. The longer-term tests are being conducted to confirm the effectiveness of the sorbents tested over extended operation and to determine balance-of-plant impacts. This reports presents the results of the short-term tests; the long-term test results will be reported in a later document. The short-term test results showed that three of the four reagents tested, dolomite powder, commercial magnesium hydroxide slurry, and byproduct magnesium hydroxide slurry, were able to achieve 90% or greater removal of sulfuric acid compared to baseline levels. The molar ratio of alkali to flue gas sulfuric acid content (under baseline conditions) required to achieve 90% sulfuric acid removal was lowest for the byproduct magnesium hydroxide slurry. However, this result may be confounded because this was the only one of the three slurries tested with injection near the top of the furnace across from the pendant superheater platens. Injection at the higher level was demonstrated to be advantageous for this reagent over injection lower in the furnace, where the other slurries were tested.

  4. SULFURIC ACID REMOVAL PROCESS EVALUATION: SHORT-TERM RESULTS

    SciTech Connect

    Gary M. Blythe; Richard McMillan

    2002-03-04

    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. Sulfuric acid controls are becoming of increasing interest to utilities with coal-fired units for a number of reasons. Sulfuric acid is a Toxic Release Inventory species, a precursor to acid aerosol/condensable emissions, and can cause a variety of 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 SCR for NOX control on some coal-fired plants, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project is testing the effectiveness of furnace injection of four different calcium- and/or magnesium-based alkaline sorbents on full-scale utility boilers. These reagents have been tested during four one- to two-week tests conducted on two FirstEnergy Bruce Mansfield Plant units. One of the sorbents tested was a magnesium hydroxide slurry produced from a wet flue gas desulfurization system waste stream, from a system that employs a Thiosorbic{reg_sign} Lime scrubbing process. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercial magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners, while the other three reagents were injected as slurries through air-atomizing nozzles into the front wall of upper furnace, either across from the nose of the furnace or across from the pendant superheater tubes. After completing the four one- to two-week tests, the most promising sorbents were selected for longer-term (approximately 25-day) full-scale tests. The longer-term tests are being conducted to confirm the effectiveness of the sorbents tested over extended operation and to determine balance-of-plant impacts. This reports presents the results of the short-term tests; the long-term test results will be reported in a later document. The short-term test results showed that three of the four reagents tested, dolomite powder, commercial magnesium hydroxide slurry, and byproduct magnesium hydroxide slurry, were able to achieve 90% or greater removal of sulfuric acid compared to baseline levels. The molar ratio of alkali to flue gas sulfuric acid content (under baseline conditions) required to achieve 90% sulfuric acid removal was lowest for the byproduct magnesium hydroxide slurry. However, this result may be confounded because this was the only one of the three slurries tested with injection near the top of the furnace across from the pendant superheater platens. Injection at the higher level was demonstrated to be advantageous for this reagent over injection lower in the furnace, where the other slurries were tested.

  5. The effect of confinement on dynamics and rheology of dilute deoxyribose nucleic acid solutions. II. Effective

    E-print Network

    Shaqfeh, Eric

    The effect of confinement on dynamics and rheology of dilute deoxyribose nucleic acid solutions. II the effect of confinement on deoxyribose nucleic acid rheology and chain dynamics. We present results these findings to microchannel flows to study the rhe- ology and chain dynamics of dilute deoxyribose nucleic

  6. Elucidating the Role of Ferrous Ion Cocatalyst in Enhancing Dilute Acid Pretreatment of Lignocellulosic Biomass

    Microsoft Academic Search

    H. Wei; B. S. Donohoe; T. B. Vinzant; P. N. Ciesielski; W. Wang; L. M. Gedvilas; Y. Zeng; D. K. Johnson; S. Y. Ding; M. E. Himmel; M. P. Tucker

    2011-01-01

    Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and

  7. The application research on the production control of dilute acid delinting

    Microsoft Academic Search

    Wang Guifeng; Guan Hongjun

    2009-01-01

    This paper focused on the existent technology problems in the dilute acid delinting of cotton seed, it first introduced the traditional process of dilute acid delinting, then combined with the automatic control technology and information processing technology of the controling of concentration, temperature and so on during the production process, rebuilt the production process and advanced the framework model about

  8. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions: Determination of Henry's Law solubility

    SciTech Connect

    Reihs, C.M.; Golden, D.M.; Tolbert, M.A. (SRI International, Menlo Park, CA (USA))

    1990-09-20

    A Knudsen cell flow reactor is used to study the uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate. Henry's law solubility constants are determined using the time dependence of the measured nitric acid uptake efficiencies. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 weight percent sulfuric acid over a temperature range from 188 to 240 K. In general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and decreasing temperature. Over the reported temperature range the solubilities are cast in the form H* = A exp(B/T), where A = 7.47 {times} 10{sup {minus}8} M/atm, B = 7.16 {times} 10{sup 3}K for 58% H{sub 2}SO{sub 4}; A = 0.202 M/atm, B = 3.19 {times} 10{sup 3}K for 66% H{sub 2}SO{sub 4}; A = 8.54 {times} 10{sup {minus}3} M/atm, B = 3.55 {times} 10{sup 3} K for 74% H{sub 2}SO{sub 4}; and A = 3.56 {times} 10{sup {minus}3} M/atm, B = 3.32 {times} 10{sup 3} K for 87% H{sub 2}SO{sub 4}. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase. The ratio of condensed to gas phase nitric acid is less than 10{sup {minus}4} even under conditions of highly elevated sulfuric acid loading.

  9. SULFURIC ACID REMOVAL PROCESS EVALUATION: LONG-TERM RESULTS

    SciTech Connect

    Gary M. Blythe; Richard McMillan

    2002-07-03

    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 project is being 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 Corp., the Tennessee Valley Authority, and Dravo Lime, Inc. Sulfuric acid controls are becoming of increasing interest to power generators with coal-fired units for a number of reasons. Sulfuric acid is a Toxic Release Inventory species and can cause a variety of 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 NO{sub x} control on many coal-fired plants, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project previously tested the effectiveness of furnace injection of four different calcium-and/or magnesium-based alkaline sorbents on full-scale utility boilers. These reagents were tested during four one- to two-week tests conducted on two FirstEnergy Bruce Mansfield Plant (BMP) units. One of the sorbents tested was a magnesium hydroxide byproduct slurry produced from a modified Thiosorbic{reg_sign} Lime wet flue gas desulfurization system. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercial magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners, while the other three reagents were injected as slurries through air-atomizing nozzles inserted through the front wall of the upper furnace, either across from the nose of the furnace or across from the pendant superheater tubes. 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 the effectiveness of the sorbents tested over extended operation on two different boilers, and to determine balance-of-plant impacts. The first long-term test was conducted on FirstEnergy's BMP, Unit 3, and the second test was conducted on AEP's Gavin Plant, Unit 1. The Gavin Plant testing provided an opportunity to evaluate the effects of sorbent injected into the furnace on SO{sub 3} formed across an operating SCR reactor. This report presents the results from those long-term tests. The tests determined the effectiveness of injecting commercially available magnesium hydroxide slurry (Gavin Plant) and byproduct magnesium hydroxide slurry (both Gavin Plant and BMP) for sulfuric acid control. The results show that injecting either slurry could achieve up to 70 to 75% overall sulfuric acid removal. At BMP, this 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 NOX control than at removing SO{sub 3} formed in the furnace. The long-term tests also determined balance-of-plant impacts from slurry injection during the two tests. These include impacts on boiler back-end temperatures and pressure drops, SCR catalyst properties, ESP performance, removal of other flue gas species, and flue gas opacity. For the most part the balance-of-plant impacts were neutral to positive, although adverse effects on ESP performance became an issue during the BMP test.

  10. Theoretical studies of sulfuric acid monohydrate: Neutral or ionic complex?

    NASA Astrophysics Data System (ADS)

    Kurdi, L.; Kochanski, E.

    1989-06-01

    The formation of a complex between one water and one sulfuric acid molecule has been studied using ab initio SCF-MO-LCGO calculations. A stable structure has been found for the neutral complex, with a stabilization energy of about 16 kcal/mol and an intermolecular O?O distance of about 2.656 Å. Similar studies on the complex H 3O +-HSO 4-, with a geometry suggested by the experimental monohydrate crystal structure, have shown that, although the stability is considerable (at least 137 kcal/mol) with respect to the isolated ions, the ionic complex is less stable than the isolated neutral molecules.

  11. Synthesis of sulfur-35-labeled glycyrrhizic acid glycopeptide with methionine

    SciTech Connect

    Baltina, L.A.; Kondratenko, R.M.; Kuvatov, Yu.G.; Murinov, Yu.I.; Tolstikov, G.A.

    1988-11-01

    To carry out pharmacokinetic investigations, we prepared sulfur-35-labeled protected glycyrrhizic acid glycopeptide with methionine by the reaction of pentaacetylglycyrrhizic trichloride with a small excess of (/sup 35/S)-methionine methyl ester hydrochloride. Melting points were determined on a Boetius microscopic stage. The IR spectra were recorded with a UR-20 spectrograph in mineral oil. The UV spectra were measured with a Specord UV-vis spectrophotometer in ethanol. The specific rotation was determined with a Perkin-Elmer 141 M polarimeter in a 1-dm-long tube. The radioactivity of the /sup 35/S-labeled compounds was measured by a scintillation method with an Izokan-300 counter.

  12. Effects of simulated rain acidified with sulfuric acid on host-parasite interactions

    Microsoft Academic Search

    Shriner

    1974-01-01

    The acidity of precipitation in certain regions of the world, including northern Europe and the Northeastern United States, has increased during the past decade. An important contributing factor is an increase in strong acids such as sulfuric and nitric, which can result from sulfur dioxide and nitrous oxide air pollution. A major impediment to studying effects of acid rain is

  13. EFFECTS OF DIFFERENT HARVEST TIME AND SULFUR FERTILIZATION ON AMINO ACID COMPOSITION OF LENTIL

    Microsoft Academic Search

    Yucel Kesli; M. Sait Adak

    2012-01-01

    The effects of sulfur (S) fertilization and harvest time on amino acid composition of seeds of field-grown lentil (Lens culinaris Medik.) at two different sites were studied. The aim of this study was to determine amino acid content of seed protein and to increase low levels of sulfur amino acids and trytophan in lentil seeds, which are major components for

  14. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL

    SciTech Connect

    Gary M. Blythe

    2003-06-01

    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, 2002 through March 31, 2003. 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 Group is the prime contractor. This is the seventh reporting period for the subject Cooperative Agreement. During previous reporting periods, 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 (both Gavin Plant 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 SO3 removal results were presented in the semi-annual Technical Progress Report for the time period April 1, 2001 through September 30, 2001. Additional balance of plant impact information for the two tests was reported in the Technical Progress Report for the time period October 1, 2001 through March 30, 2002. Additional information became available about the effects of byproduct magnesium hydroxide injection on SCR catalyst coupons during the long-term test at BMP, and those results were reported in the previous report (April 1, 2002 through September 30, 2002). During the current period, there was no technical progress to report, because all planned testing as part of this project has been completed. The project period of performance was extended to allow the conduct of testing of another SO{sub 3} control technology, the sodium bisulfite injection process. However, these additional tests have not yet been conducted.

  15. Hydration of pure and base-Containing sulfuric acid clusters studied by computational chemistry methods

    NASA Astrophysics Data System (ADS)

    Henschel, Henning; Ortega, Ismael K.; Kupiainen, Oona; Olenius, Tinja; Kurtén, Theo; Vehkamäki, Hanna

    2013-05-01

    The formation of hydrates of small molecular sulfuric acid clusters and cluster containing both sulfuric acid and base (ammonia or dimethylamine) has been studied by means of computational chemistry. Using a combined ab initio/density functional approach, formation energies of clusters with up to four sulfuric acid molecules, and up to two base molecules, have been calculated. Consequences for the hydration level of the corresponding clusters have been modelled. While the majority of pure sulfuric acid cluster are comparatively strongly hydrated, base containing cluster were found to be less hydrophilic. Dimethylamine is particularly effective in lowering the hydrophilicity of the cluster. Implications of the hydration profiles on atmospheric processes are discussed.

  16. Measurement of The Conversion Efficiency of Fuel Sulfur To Sulfuric Acid In An Aircraft Jet Engine Combustor Rig

    NASA Astrophysics Data System (ADS)

    Kiendler, A.; Wilhelm, S.; Wohlfrom, K. H.; Arnold, F.

    Combustion of sulfur containing fuels leads to the formation of aseous sulfuric acid (GSA) which may form new volatile aerosol particles or condense on aerosol particles. Measurements of GSA were made within the framework of the PARTEMIS (measure- ment and prediction of emissions of aerosols and gaseous precursors from gas turbine engines) project. The concentration of gaseous sulfuric acid was measured at the exit plane of a combustor rig run by Qinetiq (former DERA, Defence Evaluation and Re- search Agency). Measurements werde made for different conditions including two power settings (high pressure cruise and low pressure cruise) and 3 fuel sulfur con- tents (FSC, 50, 410 and 1270 ppm). The concentration of GSA was maesured using a chemical ionization mass spectrometer equipped with an ion trap. GSA concentration ranging from 2 to 250 ppb were measured at the exit plane. Correlating these values with the total sulfur emitted in the combustion one finds a linear dependence. The con- version efficiency ranges between 0.4 and 1 % with the most probable value being 0.6 to 0.7%. This supports the view that the efficiency of fuel sulfur conversion to sulfur VI in a jet engine combustor is relatively low. This conclusion is in conflict with some previous hypotheses.

  17. Use of PT and PTG textolites in sulfuric acid electrofilters

    SciTech Connect

    Udalova, V.I.

    1984-03-01

    This article examines structural laminar plastics in ShMK electrofilters to determine the possibilities of using these materials for producing load-carrying structures of the precipitation system with plastic electrodes. The research was conducted on chemically, thermally, and moisture-resistant difficult-to-combust commercial textolites PT and PTG (graphitized) in the form of sheets with a thickness of respectively 10 and 4.5 mm. Industrial tests on textolites were conducted in an ShMK-9.6 electrofilter installed in the first stage of gas scrubbing in the flashing section of the sulfuric acid contact shop for 3900 h. The chemical stability of the materials was evaluated on the basis of the changes of the weight, linear dimensions, and external appearance of the specimens (screening tests), and on the basis of the variation of the weight and short-term strength in tensile testing. It is established that the textolites PT and PTG with a thickness of 10 mm can be used in the load-carrying structure consisting of two strips with electrode plates fixed between them. The use of 400 kg of textolite for producing suspension beams for sulfuric acid plate electrofilters with electrodes made of plastics made it possible to save 715 kg of lead and 610 kg of carbon steel.

  18. FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID REMOVAL

    SciTech Connect

    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 different boilers, and to determine balance-of-plant impacts. The first long-term test was conducted on FirstEnergy's BMP Unit 3, and the second was conducted on AEP's Gavin Plant, Unit 1. The Gavin Plant test provided an opportunity to evaluate the effects of sorbent injected into the furnace on SO{sub 3} formed across an operating SCR reactor. A final task in the project was to compare projected costs for furnace injection of magnesium hydroxide slurries to estimated costs for other potential sulfuric acid control technologies. Estimates were developed for reagent and utility costs, and capital costs, for furnace injection of magnesium hydroxide slurries and seven other sulfuric acid control technologies. The estimates were based on retrofit application to a model coal-fired plant.

  19. Tolerance of S. cerevisiae and Z. mobilis to inhibitors produced during dilute acid hydrolysis of soybean meal.

    PubMed

    Lujan-Rhenals, Deivis E; Morawicki, Rubén O; Ricke, Steven C

    2014-01-01

    The objective of this research was to determine the minimum inhibitory concentration of 5-hydroxymethyl furfural, furfural, and acetic acid on Saccharomyces cerevisiae (NRRL Y-2233) and Zymomonas mobilis subspecies mobilis (NRRL B-4286) in both detoxified hydrolyzed soybean meal and synthetic YM broth spiked with the three compounds. Soybean meal was hydrolyzed with dilute sulfuric acid (0.0, 0.5, 1.25, and 2.0% wt v(-1)) at three temperatures (105, 120, and 135°C) and three durations (15, 30, and 45 min) followed by detoxification with activated carbon. Of all the combinations, only the treatments obtained at 135°C, 2.0% H2SO4, and 45 min and the one at 135°C, 1.25% H2SO4, and 45 min showed inhibition in the growth of the tested microorganisms. Spiked YM broths showed inhibition for the highest levels of inhibitors, either applied individually or in combination. PMID:24502218

  20. The sulfidation of dilute Co-Cr alloys at low sulfur partial pressures

    Microsoft Academic Search

    S. K. Verma; D. P. Whittle; J. Stringer

    1972-01-01

    The sulfidation of pure chromium and Co-Cr alloys containing 1, 5, 10, 17, and 25 wt. % Cr in H2-1%H2S at 1000°C has been studied in detail by thermogravimetric methods, metallography, and electron probe microanalysis. In this gas mixture, which has an effective sulfur partial pressure of 5×10?4 Torr, only CrS is formed, on all the alloys containing greater than

  1. Synergy effect of naphthenic acid corrosion and sulfur corrosion in crude oil distillation unit

    NASA Astrophysics Data System (ADS)

    Huang, B. S.; Yin, W. F.; Sang, D. H.; Jiang, Z. Y.

    2012-10-01

    The synergy effect of naphthenic acid corrosion and sulfur corrosion at high temperature in crude oil distillation unit was studied using Q235 carbon-manganese steel and 316 stainless steel. The corrosion of Q235 and 316 in corrosion media containing sulfur and/or naphthenic acid at 280 °C was investigated by weight loss, scanning electron microscope (SEM), EDS and X-ray diffractometer (XRD) analysis. The results showed that in corrosion media containing only sulfur, the corrosion rate of Q235 and 316 first increased and then decreased with the increase of sulfur content. In corrosion media containing naphthenic acid and sulfur, with the variations of acid value or sulfur content, the synergy effect of naphthenic acid corrosion and sulfur corrosion has a great influence on the corrosion rate of Q235 and 316. It was indicated that the sulfur accelerated naphthenic acid corrosion below a certain sulfur content but prevented naphthenic acid corrosion above that. The corrosion products on two steels after exposure to corrosion media were investigated. The stable Cr5S8 phases detected in the corrosion products film of 316 were considered as the reason why 316 has greater corrosion resistance to that of Q235.

  2. Spectroscopic identification and measurement of gaseous nitrous acid in dilute auto exhaust

    NASA Astrophysics Data System (ADS)

    Pitts, James N.; Biermann, Heinz W.; Winer, Arthur M.; Tuazon, Ernesto C.

    We report here the direct spectroscopic detection of gaseous nitrous acid (HONO) in exhaust emissions from certain light duty motor vehicles (LDMV). Co-pollutants such as nitrogen dioxide (NO 2), formaldehyde (HCHO), benzaldehyde (C 6H 5CHO) and sulfur dioxide (SO 2) were also readily determined. Nitric oxide (NO) was measured too, but with reduced accuracy. To avoid possible artifactual formation of HONO on the surfaces of conventional dilution and sampling systems (e.g. Federal and California constant volume sampling systems), an instrument was developed consisting of a multiple reflection cell without walls coupled to a u.v. differential optical absorption spectrometer (DOAS), the entire system being placed in the open air ~ 2 m from the tailpipe of the LDMV. At an optical path of 31.2 m, detection limits (in parts per 10 9, ppb) were: HONO-12; HCHO-78; C 6H 5CHO-13; NO 2-57; and SO 2-11. With this instrument, HONO levels observed in diluted exhaust ranged from nondetectable (< 12 ppb) for a 1982 California car with an effective 3-way catalyst (and associated low NO x emissions), to ~ 300 ppb for a heavily used 1974 station wagon having high NO x emissions and run on leaded gasoline. While the number of LDMV tested was too small for statistical treatment, our results show that the older portion of the total LDMV population (i.e. without current emission control devices) may be a significant primary source of gaseous HONO, a key precursor to photochemical air pollution and an inhalable nitrite.

  3. Obtaining fermentable sugars by dilute acid hydrolysis of hemicellulose and fast pyrolysis of cellulose.

    PubMed

    Jiang, Liqun; Zheng, Anqing; Zhao, Zengli; He, Fang; Li, Haibin; Liu, Weiguo

    2015-04-01

    The objective of this study was to get fermentable sugars by dilute acid hydrolysis of hemicellulose and fast pyrolysis of cellulose from sugarcane bagasse. Hemicellulose could be easily hydrolyzed by dilute acid as sugars. The remained solid residue of acid hydrolysis was utilized to get levoglucosan by fast pyrolysis economically. Levoglucosan yield from crystalline cellulose could be as high as 61.47%. Dilute acid hydrolysis was also a promising pretreatment for levoglucosan production from lignocellulose. The dilute acid pretreated sugarcane bagasse resulted in higher levoglucosan yield (40.50%) in fast pyrolysis by micropyrolyzer, which was more effective than water washed (29.10%) and un-pretreated (12.84%). It was mainly ascribed to the effective removal of alkali and alkaline earth metals and the accumulation of crystalline cellulose. This strategy seems a promising route to achieve inexpensive fermentable sugars from lignocellulose for biorefinery. PMID:25690683

  4. Differences in Median Ultraviolet Light Transmissions of Serial Homeopathic Dilutions of Copper Sulfate, Hypericum perforatum, and Sulfur

    PubMed Central

    Klein, Sabine D.; Sandig, Annegret; Baumgartner, Stephan; Wolf, Ursula

    2013-01-01

    Homeopathic remedies are produced by potentising, that is, the serial logarithmic dilution and succussion of a mother tincture. Techniques like ultraviolet spectroscopy, nuclear magnetic resonance, calorimetry, or thermoluminescence have been used to investigate their physical properties. In this study, homeopathic centesimal (c) potencies (6c to 30c) of copper sulfate, Hypericum perforatum, and sulfur as well as succussed water controls were prepared. Samples of these preparations were exposed to external physical factors like heat, pressure, ultraviolet radiation, or electromagnetic fields to mimic possible everyday storage conditions. The median transmissions from 190?nm to 340?nm and 220?nm to 340?nm were determined by ultraviolet light spectroscopy on five measurement days distributed over several months. Transmissions of controls and potencies of sulfur differed significantly on two of five measurement days and after exposure to physical factors. Transmissions of potencies exposed to ultraviolet light and unexposed potencies of copper sulfate and Hypericum perforatum differed significantly. Potency levels 6c to 30c were also compared, and wavelike patterns of higher and lower transmissions were found. The Kruskal-Wallis test yielded significant differences for the potency levels of all three substances. Aiming at understanding the physical properties of homeopathic preparations, this study confirmed and expanded the findings of previous studies. PMID:23401712

  5. Naphthenic acids, total acid number and sulfur content profile characterization in Isthmus and Maya crude oils

    Microsoft Academic Search

    Georgina C Laredo; Carla R López; Regina E Įlvarez; José L Cano

    2004-01-01

    In order to understand the origin of the corrosive behavior presented in the Atmospheric\\/Vacuum Distillation Unit in the Salina Cruz Refinery, Mexico, where a 90\\/10 Isthmus\\/Maya crude blend is processed, distributions of sulfur content and total acid number along the distillation curves of the Maya and Isthmus crude oils were performed. Naphthenic acids characterizations for both crude oils are also

  6. Influence of different sulfur compounds on corrosion due to naphthenic acid

    Microsoft Academic Search

    Omar Yépez

    2005-01-01

    The influence of different sulfur compounds on corrosion due to naphthenic acid was studied by means of the new method FeNCOR™. It was found that such influence occurs after the reduction of the given sulfur compound by the cathodic reaction of the overall process of naphthenic acid corrosion. When the reduction product is H2S the formation of a potentially protective

  7. What Is the Boiling Point and Heat of Vaporization of Sulfuric Acid?

    ERIC Educational Resources Information Center

    Myers, R. Thomas

    1983-01-01

    Discusses the values presented in various handbooks for the boiling point and heat of vaporization of sulfuric acid, noting discrepencies. Analyzes various approaches to data presentation, discussing the data on sulfuric acid in light of the Trouton constant. Points out the need for a more critical use of tables. (JM)

  8. Sulfuric acid and hot water treatments enhance ex vitro and in vitro germination of Hibiscus seed

    Microsoft Academic Search

    Hamidou F. Sakhanokho

    2009-01-01

    Seeds of Hibiscus dasycalyx S. F. Blake and Shiller, a federally listed candidate endangered species and native to North America and two variants of Hibiscus acetosella Welw. ex. Hiern were scarified using sulfuric acid and hot water. The effects of the scarification methods on in vitro and ex vitro germination in both species were evaluated. Sulfuric acid scarification was very

  9. EFFECTS OF ENDOGENOUS AMMONIA ON NEUTRALIZATION OF INHALED SULFURIC ACID AEROSOLS

    EPA Science Inventory

    Nine male beagle dogs were exposed by inhalation to 0, 6 and 10.5 mg/cu.m sulfuric acid aerosols with normal ammonia, increased blood ammonia, and increased inhaled ammonia to determine whether the addition of ammonia affected the toxicity of sulfuric acid aerosols. Exhaled conce...

  10. Optical constants of sulfuric acid - Application to the clouds of Venus

    Microsoft Academic Search

    K. F. Palmer; Dudley Williams

    1975-01-01

    Young (1973) and Sill (1972) have independently suggested that the clouds of Venus may well consist of particles composed of sulfuric acid molecules with attached water molecules. For a further study of this hypothesis an investigation has been conducted with the objective to supply the needed laboratory data for a wide range of sulfuric acid concentrations. Optical constants have been

  11. EFFECTS OF SULFURIC ACID RAIN ON DECOMPOSITION RATE AND CHEMICAL ELEMENT CONTENT OF HARDWOOD LEAF LITTER

    EPA Science Inventory

    Simulated sulfuric acid rain (pH 3.0, 3.5, or 4.0) or control rain (pH 5.6) was applied to decomposing leaf packs of 10 hardwood species. Changes in weight and chemical element concentrations were followed for 408 days. There was no apparent relationship between sulfuric acid rai...

  12. EFFECT OF SILICA FUME AND NATURAL POZZOLANAS ON SULFURIC ACID RESISTANCE OF DENSE CONCRETES

    Microsoft Academic Search

    H. Rahmani; A. A. Ramzanianpour

    Biogenic sulfuric acid corrosion is often a problem in sewer environments. Also in certain industrial activities sulfuric acid is used during the production process. ?t can lead to a fast degradation of the concrete structures. Therefore there is a substaintial need for construction of durable concrete structures in such environments. The porosity of concretes plays an important role in harsh

  13. THE KINETICS OF THE CORROSION OF LOW-HAFNIUM ZIRCONIUM IN AQUEOUS SULFURIC ACID SOLUTIONS

    Microsoft Academic Search

    Tennyson Smith

    1960-01-01

    The rates of corrosion of low-hafnium zirconium in aqueous sulfuric acid ; solutions over the concentration range 9 to 97% by weight, were studied. ; Corrosion was detected by measuring the concentration of zirconium in solution ; with a radioactive tracer, Zrā¹āµ. The samples first were etched in an ; aqueous hydrofluoric-nitric acid solution then placed directly into the sulfuric

  14. BIOCHEMICAL EFFECTS OF SULFURIC ACID MIST INHALATION BY HUMAN SUBJECTS WHILE AT REST

    EPA Science Inventory

    The study evaluated the effect of sulfuric acid aerosol exposure for 2 consecutive days on seven human biochemical blood parameters. A total of 20 human subjects were exposed to 100 micrograms per cu. m. sulfuric acid aerosol for 4 hr/day for 2 consecutive days. A total of 17 hum...

  15. A Demonstration of Acid Rain and Lake Acidification: Wet Deposition of Sulfur Dioxide.

    ERIC Educational Resources Information Center

    Goss, Lisa M.

    2003-01-01

    Introduces a science demonstration on the dissolution of sulfuric oxide emphasizing the concept of acid rain which is an environmental problem. Demonstrates the acidification from acid rain on two lake environments, limestone and granite. Includes safety information. (YDS)

  16. Chemistry of ascorbic acid and sulfur dioxide as an antioxidant system relevant to white wine.

    PubMed

    Barril, Célia; Clark, Andrew C; Scollary, Geoffrey R

    2012-06-30

    The impact of the combined ascorbic acid and sulfur dioxide antioxidants on white wine oxidation processes was investigated using a range of analytical techniques, including flow injection analysis for free and total sulfur dioxide and two chromatographic methods for ascorbic acid, its oxidative degradation products and phenolic compounds. The combination of different analytical techniques provided a fast and simultaneous means for the monitoring of oxidation processes in a model wine system. In addition, the initial mole ratio of sulfur dioxide to ascorbic acid was varied and the model wine complexity was increased by the inclusion of metal ions (copper(II) and iron(II)). Sulfur dioxide was found not to be a significant binder of ascorbic acid oxidative degradation products and could not prevent the formation of certain phenolic pigment precursors. The results provide a detailed insight into the ascorbic acid/sulfur dioxide antioxidant system in wine conditions. PMID:22688051

  17. Health effects of air pollutants: sulfuric acid, the old and the new.

    PubMed Central

    Amdur, M O

    1989-01-01

    Data from exposure of experimental animals and human subjects to sulfuric acid presents a consistent picture of its toxicology. Effects on airway resistance in asthmatic subjects were well predicted by data obtained on guinea pigs. Sulfuric acid increases the irritant response to ozone in both rats and man. In donkeys, rabbits, and human subjects, sulfuric acid alters clearance of particles from the lung in a similar manner. These changes resemble those produced by cigarette smoke and could well lead to chronic bronchitis. Data obtained on guinea pigs indicate that very small amounts of sulfuric acid on the surface of ultrafine metal oxide aerosols produce functional, morphological, and biochemical pulmonary effects. Such particles are typical of those emitted from coal combustion and smelting operations. Sulfate is an unsatisfactory surrogate in existing epidemiology studies. Sulfuric acid measurement is a critical need in such studies. PMID:2667973

  18. [Leaching kinetics of josephinite tailings with sulfuric acid].

    PubMed

    Chen, An-An; Zhou, Shao-Qi; Huang, Peng-Fei

    2013-07-01

    Leaching is the most important step of josephinite tailing recycle technology. This step can separate the valuable metal Mg from Si and other impure metal. Effects of sulfuric acid on leaching Mg efficiency from josephinite tailings were investigated. To obtain the leaching behavior, a modified unreacted shrinking core model that based on the experimental data was used to determine the dissolution kinetic parameters. The model was significant and showed that the dissolution of Mg2+ in josephinite tailing was controlled by the produce layer diffusion, apparent activation reaction energy E = 34.04 kJ x mol(-1). The produce layers obstruct the forward reaction of the dissolution of Mg2+. PMID:24028005

  19. Electrochromic properties of oxidized tungsten in sulfuric acid solutions

    SciTech Connect

    Yurkinskii, V.P.; Muzdhaba, V.M.; Sidorova, M.A.; Morachevskii, A.G.

    1987-08-01

    The parameters of the electrochromic process taking place on electrochemically oxidized tungsten electrodes were studied by recording current-voltage curves, making coulometric determinations, and investigating electrooptic effects in the oxide film. The electrochromic effect was studied in sulfuric acid solutions of different concentrations. The shape of the cathodic current-voltage curves is shown. The amounts of charge consumed and the contrast ratios as functions of cathodic potential of the tungsten electrode during coloration are presented. Also shown is the anodic and cathodic current as functions of time during bleaching of oxidized tungsten, plotted in different coordinates. High mobility of the protons in tungsten oxide produced by electrochemical oxidation of tungsten, relative to sputtered oxide, is shown to procure faster response of the electrochromic system.

  20. HIGH TEMPERATURE DILUTE ACID HYDROLYSIS OF WASTE CELLULOSE: BATCH AND CONTINUOUS PROCESSES

    EPA Science Inventory

    The 5-year investigation on the dilute acid hydrolysis of waste cellulose to glucose has emphasized the crucial step of continuously converting cellulose to glucose. Initial batch studies emphasized pretreatments to improve accessibility of the cellulose, and established suitable...

  1. Decomposition of sulfuric acid using solar thermal energy

    SciTech Connect

    Not Available

    1985-02-01

    A high-temperature solar-powered catalytic metallic reactor was built and tested as a first step in determining the potential applicability of metallic reactors to the Solar Fuels and Chemical Program. The temperature range of interest, 700/sup 0/ to 1000/sup 0/C, provides a serious test of the capability of metals to resist both chemical corrosion and thermal stresses. Use of metallic reactors in the Solar Fuels and Chemicals processes. Without practical metallic reactors, we will have to await scientific and engineering breakthroughs in the fields of ceramics and structural design of brittle materials before ceramic heat exchangers become practical. The tests also provided the first opportunity to demonstrate a working catalytic chemical reactor on a solar power tower using engineering materials. The chemical reaction chosen for study was sulfuric acid decomposition, the key high-temperature step to thermochemical production of hydrogen from water. This is a very clean reaction with no side reactions producing extraneous products; thus, the results may easily be extrapolated to the design of solar-powered catalytic reactors for other fuels and chemical processes. The overall program was very successful in that all major test objectives were met. The sulfuric acid decomposition reaction went essentially to completion as predicted. The selected materials of construction, Incoloy 800H, Hastelloy C-276, and Inconel 825, performed satisfactorily. The temperature inside the cavity was very uniform and well within predicted values. No unacceptable corrosion was observed. The solar-driven chemical reactor, located on top of the solar power tower, could be operated and controlled from the ground. The results of the test indicate that continued development of this concept is warranted. The next step in the development of high-temperature metallic reactors is the demonstration of such a system at higher pressures and solar flux levels.

  2. Suicidal carbon monoxide poisoning by combining formic acid and sulfuric acid within a confined space.

    PubMed

    Lin, Peter T; Dunn, William A

    2014-01-01

    Suicide by inhalation of carbon monoxide produced by mixing formic acid and sulfuric acid within a confined space is a rare method of suicide. This method is similar to the so-called "detergent suicide" method where an acid-based detergent is mixed with a sulfur source to produce hydrogen sulfide. Both methods produce a toxic gas that poses significant hazards for death investigators, first responders and bystanders. Carbon monoxide is an odorless gas, while hydrogen sulfide has a characteristic rotten eggs odor, so the risks associated with carbon monoxide are potentially greater due to lack of an important warning signal. While detergent suicides have become increasingly common in the USA, suicide with formic acid and sulfuric acid is rare with only three prior cases being reported. Greater awareness of this method among death investigators is warranted because of the special risks of accidental intoxication by toxic gas and the possibility that this method of suicide will become more common in the future. PMID:24328850

  3. Extraction of hydrochloric acid from dilute solutions by the use of organic solvents 

    E-print Network

    Pandya, Harishkumar Chandulal

    1967-01-01

    EXTRACTION OF HYDROCHLORIC ACID FROM DILUTE SOLUTIONS BY THE USE OF ORGANIC SOLVENTS A Thesis HARISHKUMAR CHANDULAL PANDYA Submitted to the Graduate College of the Texas ASM University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 1967 Major Subject: CHEMICAL ENGINEERING EXTRACTION OF HYDROCHLORIC ACID FROM DILUTE SOLUTIONS BY THE USE OF ORGANIC SOLVENTS A Thesis By HARI SHKUMAR CHANDULAL PANDYA Approved as to style and content by: airman o Committee...

  4. Involvement of intermediate sulfur species in biological reduction of elemental sulfur under acidic, hydrothermal conditions.

    PubMed

    Boyd, Eric S; Druschel, Gregory K

    2013-03-01

    The thermoacidophile and obligate elemental sulfur (S(8)(0))-reducing anaerobe Acidilobus sulfurireducens 18D70 does not associate with bulk solid-phase sulfur during S(8)(0)-dependent batch culture growth. Cyclic voltammetry indicated the production of hydrogen sulfide (H(2)S) as well as polysulfides after 1 day of batch growth of the organism at pH 3.0 and 81°C. The production of polysulfide is likely due to the abiotic reaction between S(8)(0) and the biologically produced H(2)S, as evinced by a rapid cessation of polysulfide formation when the growth temperature was decreased, inhibiting the biological production of sulfide. After an additional 5 days of growth, nanoparticulate S(8)(0) was detected in the cultivation medium, a result of the hydrolysis of polysulfides in acidic medium. To examine whether soluble polysulfides and/or nanoparticulate S(8)(0) can serve as terminal electron acceptors (TEA) supporting the growth of A. sulfurireducens, total sulfide concentration and cell density were monitored in batch cultures with S(8)(0) provided as a solid phase in the medium or with S(8)(0) sequestered in dialysis tubing. The rates of sulfide production in 7-day-old cultures with S(8)(0) sequestered in dialysis tubing with pore sizes of 12 to 14 kDa and 6 to 8 kDa were 55% and 22%, respectively, of that of cultures with S(8)(0) provided as a solid phase in the medium. These results indicate that the TEA existed in a range of particle sizes that affected its ability to diffuse through dialysis tubing of different pore sizes. Dynamic light scattering revealed that S(8)(0) particles generated through polysulfide rapidly grew in size, a rate which was influenced by the pH of the medium and the presence of organic carbon. Thus, S(8)(0) particles formed through abiological hydrolysis of polysulfide under acidic conditions appeared to serve as a growth-promoting TEA for A. sulfurireducens. PMID:23335768

  5. Acid Rain

    Microsoft Academic Search

    Gene E. Likens; Richard F. Wright; James N. Galloway; Thomas J. Butler

    1979-01-01

    Measurements of the acidity of rain and snow reveal that in parts of the eastern U.S. and of western Europe precipitation has changed from a nearly neutral solution 200 years ago to a dilute solution of sulfuric and nitric acids today. The trend is a result of the emission of sulfur and nitrogen oxides to the atmosphere accompanying the rise

  6. Pulmonary function and clearance after prolonged sulfuric acid aerosol exposure

    SciTech Connect

    Ives, P.J. (ABB Environmental, Chapel Hill, NC (United States)); Gerrity, T.R.; DeWitt, P.; Folinsbee, L.J. (Environmental Protection Agency, Chapel Hill, NC (United States))

    1991-03-15

    The authors studied pulmonary function and clearance responses after a 4 H exposure to 75-100 {mu}g/m{sup 3} sulfuric acid aerosol (SAA). Healthy subjects, who exercised for 30 min/H at ventilation of about 25 L/min, were exposed once to clean air and once to SAA. Oral hygiene and acidic juice gargle were used to minimize oral ammonia. Lung function tests, including spirometry, plethysmography, and partial flow-volume (PEFV) curves were performed before and after exposure. Clearance of 99m-Technetium labeled iron oxide was assessed after each exposure. The first moment of fractional tracheobronchial retention (M1TBR), after correcting for 24 H retention and normalizing to time zero, was used as an index of clearance. There were no significant changes in lung volumes, airways resistance, or maximum expiratory flows after SAA exposure. Flow at 40% of total lung capacity on PEFV curves decreased 17% (NS) after SAA exposure. Tracheobronchial clearance was accelerated after a single exposure to SAA; M1TBR decreased from 73 {plus minus} 5 min (air) to 69 {plus minus} 5 min (SAA). These results suggest that acute prolonged exposure to low levels of SAA has minimal effects on lung mechanics in healthy subjects but does produce a modest acceleration of particle clearance.

  7. Immersed effects of Ta and Zr compounds on activity of oxygen reduction reaction in sulfuric acid

    NASA Astrophysics Data System (ADS)

    Matsuzawa, Koichi; Nozawa, Kazuhiro; Yamauchi, Kyosuke; Ishihara, Akimitsu; Mitsushima, Shigenori; Ota, Ken-ichiro

    2013-03-01

    The immersed effects of Ta and Zr compounds (Ta-CNO and Zr-CNO) on the activity of oxygen reduction reaction (ORR) have been investigated in the sulfuric acid. The concentration of Zr on Zr-CNO was higher than that of Pt on Pt black. The concentration of Ta on Ta-CNO was almost the same as that of Pt on Pt black in sulfuric acid. The catalytic activity of Zr-CNO for the ORR decreased with time. In contrast, the catalytic activity of Ta-CNO for the ORR was maintained up to 1050 h in the sulfuric acid.

  8. Ion Irradiation of Sulfuric Acid: Implications for its Stability on Europa

    NASA Technical Reports Server (NTRS)

    Loeffler, M. J.; Hudson, R. L.; Moore, M. H.

    2010-01-01

    The Galileo near-infrared mapping spectrometer (NIMS) detected regions on Europa's surface containing distorted H2O bands. This distortion likely indicates that there are other molecules mixed with the water ice. Based on spectral comparison, some of the leading possibilities are sulfuric acid, salts. or possibly H3O(+). Previous laboratory studies have shown that sulfuric acid can be created by irradiation of H2OSO2 mixtures, and both molecules are present on Europa. In this project, we were interested in investigating the radiation stability of sulfuric acid (H2SO4) and determining its lifetime on the surface of Europa.

  9. Sulfuric acid karst and its relationship to hydrocarbon reservoir porosity, native sulfur deposits, and the origin of Mississippi Valley-type ore deposits

    SciTech Connect

    Hill, C.A. (Hill (Carol A.), Albuquerque, NM (United States))

    1993-03-01

    The Delaware Basin of southeastern New Mexico and West Texas contains hydrocarbons and native sulfur in the basin and sulfuric acid-formed caves and Mississippi Valley-type (MVT) ore deposits around the margins of the basin. Hydrocarbons reacting with sulfate evaporite rock produced hydrogen sulfide gas, which gas oxidized to native sulfur in the basin and which gas also migrated from basin to reef and accumulated there in structural and stratigraphic traps. In the reduced zone of the carbonate reef margin the H[sub 2]S combined with metal-chloride complexes to form MVTs, and in the oxidized zone later in time the H[sub 2]S formed sulfuric acid which dissolved out the famous caves of the region (e.g., Carlsbad Cavern, Lechuguilla Cave). Sulfuric acid karst can be recognized by the discontinuity, large size, and spongework nature of its cave passages, and by the presence of native sulfur, endellite, and large gypsum deposits within these caves. Sulfuric acid oilfield karst refers to cavernous porosity filled with hydrocarbons and can be produced by the mixing of waters of different H[sub 2]S content or by the oxidation of H[sub 2]S to sulfuric acid. Sulfur and carbon-oxygen isotopes have been used to establish and trace the sequence of related hydrocarbon, sulfur, MVT, and karst events in the Delaware Basin.

  10. Size-resolved sulfuric acid mist concentrations at phosphate fertilizer manufacturing facilities in Florida.

    PubMed

    Hsu, Yu-Mei; Wu, Chang-Yu; Lundgren, Dale A; Birky, Brian K

    2007-01-01

    Strong inorganic acid mists containing sulfuric acid were identified as a 'known human carcinogen' in a National Toxicology Program (NTP) report where phosphate fertilizer manufacture was listed as one of many occupational exposures to strong acids. To properly assess the occupational exposure to sulfuric acid mists in modern facilities, approved National Institute for Occupational Safety and Health (NIOSH) Method 7903 and a cascade impactor were used for measuring the total sulfuric acid mist concentration and size-resolved sulfuric acid mist concentration, respectively. Sampling was conducted at eight phosphate fertilizer plants and two background sites in Florida and there were 24 sampling sites in these plants. Samples were analyzed by ion chromatography (IC) to quantify the water-soluble ion species. The highest sulfuric acid concentrations by the cascade impactor were obtained at the sulfuric acid pump tank area. When high aerosol mass concentrations (100 micro g m(-3)) were observed at this area, the sulfuric acid mists were in the coarse mode. The geometric mean sulfuric acid concentrations (+/-geometric standard deviation) of PM(23) (aerodynamic cut size smaller than 23 micro m), PM(10) and PM(2.5) from the cascade impactor were 41.7 (+/-5.5), 37.9 (+/-5.8) and 22.1 (+/-4.5) micro g m(-3), respectively. The geometric mean (+/-geometric standard deviation) for total sulfuric acid concentration from the NIOSH method samples was 143 (+/-5.08) micro g m(-3). Sulfuric acid mist concentrations varied significantly among the plants and even at the same location. The measurements by the NIOSH method were 1.5-229 times higher than those by the cascade impactor. Moreover, using the NIOSH method, the sulfuric acid concentrations measured at the lower flow rate (0.30 Lpm) were higher than those at the higher flow rate (0.45 Lpm). One possible reason for the significant differences between the results from the cascade impactor and the NIOSH method is the potential artifact resulting from the interaction of SO(2) with silica gel and glass fiber used in the NIOSH method. PMID:17032693

  11. Sulfur amino acid metabolism in Zucker diabetic fatty rats.

    PubMed

    Kwak, Hui Chan; Kim, Young-Mi; Oh, Soo Jin; Kim, Sang Kyum

    2015-08-01

    The present study was aimed to investigate the metabolomics of sulfur amino acids in Zucker diabetic fatty (ZDF) rats, an obese type 2 diabetic animal model. Plasma levels of total cysteine, homocysteine and methionine, but not glutathione (GSH) were markedly decreased in ZDF rats. Hepatic methionine, homocysteine, cysteine, betaine, taurine, spermidine and spermine were also decreased. There are no significant difference in hepatic S-adenosylmethionine, S-adenosylhomocysteine, GSH, GSH disulfide, hypotaurine and putrescine between control and ZDF rats. Hepatic SAH hydrolase, betaine-homocysteine methyltransferase and methylene tetrahydrofolate reductase were up-regulated while activities of gamma-glutamylcysteine ligase and methionine synthase were decreased. The area under the curve (AUC) of methionine and methionine-d4 was not significantly different in control and ZDF rats treated with a mixture of methionine (60mg/kg) and methionine-d4 (20mg/kg). Moreover, the AUC of the increase in plasma total homocysteine was comparable between two groups, although the homocysteine concentration curve was shifted leftward in ZDF rats, suggesting that the plasma total homocysteine after the methionine loading was rapidly increased and normalized in ZDF rats. These results show that the AUC of plasma homocysteine is not responsive to the up-regulation of hepatic BHMT in ZDF rats. The present study suggests that the decrease in hepatic methionine may be responsible for the decreases in its metabolites, such as homocysteine, cysteine, and taurine in liver and consequently decreased plasma homocysteine levels. PMID:26047850

  12. Diversity of Sulfur Compound Production in Lactic Acid Bacteria1

    Microsoft Academic Search

    K. E. Seefeldt; B. C. Weimer

    2000-01-01

    Volatile sulfur compounds such as methanethiol, di- methyl disulfide, dimethyl trisulfide, and hydrogen sul- fide constitute an important fraction of Cheddar cheese flavor. These compounds are products of the catabolism of methionine and cysteine by bacteria in the cheese matrix. The objectives of this study were to examine the levels and types of volatile sulfur compounds produced from methionine by

  13. First-principles molecular dynamics simulations of (sulfuric acid)1(dimethylamine)1 cluster formation

    NASA Astrophysics Data System (ADS)

    Loukonen, Ville; Bork, Nicolai; Vehkamäki, Hanna

    2013-05-01

    The clustering process (sulfuric acid) + (base)?(sulfuric acid)1(base)1 is of fundamental importance in the atmospheric new-particle formation. Especially interesting are the collisions where a proton transfer reaction can happen, as the reaction often leads to relatively strongly bound clusters. Here, we studied the clustering process of (sulfuric acid) + (dimethylamine) ? (sulfuric acid)1(dimethylamine)1 using first-principles molecular dynamics simulations. The collision of the two molecules was simulated starting with various spatial orientations and the evolution of the cluster was followed in the NVE ensemble. The simulations suggest that the proton transfer reaction takes place regardless of the intial collision orientation. However, due to the energy released in the process, the newly-formed cluster is not able to reach the minimun energy configuration, which might affect the following growth processes.

  14. Oxidation of the sulfur-containing amino acids in recombinant human ?1-antitrypsin

    E-print Network

    Griffiths, Steven W

    2002-01-01

    Oxidation is one of the most prevalent forms of chemical modification, and the sulfur-containing amino acids, methionine and cysteine, are susceptible to modification by a wide array of oxidants. Aberrant oxidation reactions ...

  15. Sulfuric Acid droplet formation and growth in the stratosphere after the 1982 eruption of el chichon.

    PubMed

    Hofmann, D J; Rosen, J M

    1983-10-21

    The eruption of El Chichón Volcano in March and April 1982 resulted in the nucleation of large numbers of new sulfuric acid droplets and an increase by nearly an order of magnitude in the size of the preexisting particles in the stratosphere. Nearly 10(7) metric tons of sulfuric acid remained in the stratosphere by the end of 1982, about 40 times as much as was deposited by Mount St. Helens in 1980. PMID:17734833

  16. Formation of highly hygroscopic soot aerosols upon internal mixing with sulfuric acid vapor

    Microsoft Academic Search

    Alexei F. Khalizov; Renyi Zhang; Dan Zhang; Huaxin Xue; Joakim Pagels; Peter H. McMurry

    2009-01-01

    The hygroscopic properties of submicron soot particles during internal mixing with gaseous sulfuric acid have been investigated using a combined tandem differential mobility analyzer (TDMA) and differential mobility analyzer–aerosol particle mass analyzer (DMA-APM) technique. Fresh particles exhibit no change in mobility size and mass at subsaturated conditions, whereas particles exposed to gaseous sulfuric acid (109–1010 molecule cm?3, 12 s contact

  17. Formation rates, stability and reactivity of sulfuric acid - amine clusters predicted by computational chemistry

    NASA Astrophysics Data System (ADS)

    Kurtén, Theo; Ortega, Ismael; Kupiainen, Oona; Olenius, Tinja; Loukonen, Ville; Reiman, Heidi; McGrath, Matthew; Vehkamäki, Hanna

    2013-04-01

    Despite the importance of atmospheric particle formation for both climate and air quality, both experiments and non-empirical models using e.g. sulfuric acid, ammonia and water as condensing vapors have so far been unable to reproduce atmospheric observations using realistic trace gas concentrations. Recent experimental and theoretical evidence has shown that this mystery is likely resolved by amines. Combining first-principles evaporation rates for sulfuric acid - dimethylamine clusters with cluster kinetic modeling, we show that even sub-ppt concentrations of amines, together with atmospherically realistic concentrations of sulfuric acid, result in formation rates close to those observed in the atmosphere. Our simulated cluster formation rates are also close to, though somewhat larger than, those measured at the CLOUD experiment in CERN for both sulfuric acid - ammonia and sulfuric acid - dimethylamine systems. A sensitivity analysis indicates that the remaining discrepancy for the sulfuric acid - amine particle formation rates is likely caused by steric hindrances to cluster formation (due to alkyl groups of the amine molecules) rather than by significant errors in the evaporation rates. First-principles molecular dynamic and reaction kinetic modeling shed further light on the microscopic physics and chemistry of sulfuric acid - amine clusters. For example, while the number and type of hydrogen bonds in the clusters typically reach their equilibrium values on a picosecond timescale, and the overall bonding patterns predicted by traditional "static" quantum chemical calculations seem to be stable, the individual atoms participating in the hydrogen bonds continuously change at atmospherically realistic temperatures. From a chemical reactivity perspective, we have also discovered a surprising phenomenon: clustering with sulfuric acid molecules slightly increases the activation energy required for the abstraction of alkyl hydrogens from amine molecules. This implies that the oxidation rate of amines by OH and possibly other oxidants may be decreased by clustering, thus prolonging the chemical lifetime of amines in the air.

  18. Corrosion properties of amorphous iron-zirconium films in 1N sulfuric acid

    Microsoft Academic Search

    L. D. McCormick; C. L. Chien; C. R. Molock; N. S. Wheeler

    1984-01-01

    Amorphous iron-zirconium alloys, ranging in composition from FeāāZrāā to FeāāZrāā, hav been studied by anodic polarization and passivation decay in 1N sulfuric acid. The results showed a compositional enhancement o corrosion resistance with increasing zirconium concentration. Auger electron spectroscopy indicated that exposure to th sulfuric acid solution enhances the surface zirconium concentration with respect to the bulk of the exposed

  19. Effect of sulfuric acid coating on heterogeneous ice nucleation by soot aerosol particles

    Microsoft Academic Search

    O. Möhler; S. Büttner; C. Linke; M. Schnaiter; H. Saathoff; O. Stetzer; R. Wagner; M. Krämer; A. Mangold; V. Ebert; U. Schurath

    2005-01-01

    The low-temperature aerosol and cloud chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) of Forschungszentrum Karlsruhe was used to investigate the effect of sulfuric acid coating on the ice nucleation efficiency of soot aerosol particles from a spark discharge generator. The uncoated (sulfuric acid–coated) soot aerosol showed a nearly lognormal size distribution with number concentrations of 300–5000 cm?3 (2500–56,000

  20. Effects of sulfuric acid and nitrogen deposition on mineral nutrition of Picea abies (L.) Karst.

    E-print Network

    Paris-Sud XI, Université de

    ecosystems, saplings have been sprayed with artificial acid rain, structured soil samples have been extractedEffects of sulfuric acid and nitrogen deposition on mineral nutrition of Picea abies (L.) Karst. B sites in the Fichtel- gebirge, and low fogwater pH (Trautner, 1989) of 2.2 indicate a high acid stress

  1. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  2. Photon and Water Mediated Sulfur Oxide and Acid Chemistry in the Atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Kroll, Jay A.; Vaida, Veronica

    2014-06-01

    Sulfur compounds have been observed in the atmospheres of a number of planetary bodies in our solar system including Venus, Earth, Mars, Io, Europa, and Callisto. The global cloud cover on Venus located at an altitude between 50 and 80 kilometers is composed primarily of sulfuric acid (H_2SO_4) and water. Planetary photochemical models have attempted to explain observations of sulfuric acid and sulfur oxides with significant discrepancies remaining between models and observation. In particular, high SO_2 mixing ratios are observed above 90 km which exceed model predictions by orders of magnitude. Work recently done in the Vaida lab has shown red light can drive photochemistry through overtone pumping for acids like H_2SO_4 and has been successful in explaining much of the sulfur chemistry in Earth's atmosphere. Water can have a number of interesting effects such as catalysis, suppression, and anti-catalysis of thermal and photochemical processes. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and present spectroscopic studies to document such effects. We investigate these reactions using FTIR and UV/Vis spectroscopy and will report on our findings.

  3. Fundamental study on kinetics and transport phenomena in low water dilute acid total hydrolysis of cellulosic biomass

    SciTech Connect

    Auburn University

    2004-04-07

    The overall objective of this research is to delineate the process of the dilute-acid hydrolysis of biomass and seek better understanding of the reactions involving dilute-acid treatment of lignocellulosic biomass. Specifically the scope of the work entails the following two primary technical elements: Verification of the heterogeneous nature of the reaction mechanism in dilute-acid hydrolysis of cellulosic component of the biomass. Experimental investigation to identify the overall reaction pattern and the kinetic constants associated with dilute-acid hydrolysis of the cellulosic component of the agricultural residues.

  4. Catalytic effect of water, formic acid, or sulfuric acid on the reaction of formaldehyde with OH radicals.

    PubMed

    Zhang, Weichao; Du, Benni; Qin, Zhenglong

    2014-07-01

    In this paper, for the hydrogen abstraction reaction of HCHO by OH radicals assisted by water, formic acid, or sulfur acid, the possible reaction mechanisms and kinetics have been investigated theoretically using quantum chemistry methods and transition-state theory. The potential energy surfaces calculated at the CCSD(T)/6-311++G(df,pd)//MP2(full)/6-311++G(df,pd) levels of theory reveal that, due to the formation of strong hydrogen bond(s), the relative energies of the transition states involving catalyst are significantly reduced compared to that reaction without catalyst. However, the kinetics calculations show that the rate constants are smaller by about 3, 9, or 10 orders of magnitude for water, formic acid, or sulfur acid assisted reactions than that uncatalyzed reaction, respectively. Consequently, none of the water, formic acid, or sulfur acid can accelerate the title reaction in the atmosphere. PMID:24927334

  5. Dental erosion and sulfuric ion exposure levels in individuals working with sulfuric acid in lead storage battery manufacturing plant measured with mouth-rinse index.

    PubMed

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, p<0.005), calcium and magnesium concentrations (r=0.61, p<0.005), Ca/Mg and calcium concentrations (r=0.64, p<0.005), and sulfuric ion and magnesium concentrations (r=0.55, p<0.005). Negative correlations were found between sulfuric ion concentrations and pH levels (r=-0.31, p<0.01), and magnesium concentrations and pH levels (r=-0.32, p<0.01). This suggests that mouth rinse from employees working with sulfuric acid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure. PMID:21139372

  6. Reduction in environmental impact of sulfuric acid hydrolysis of bamboo for production of fuel ethanol.

    PubMed

    Sun, Zhao-Yong; Tang, Yue-Qin; Morimura, Shigeru; Kida, Kenji

    2013-01-01

    Fuel ethanol can be produced from bamboo by concentrated sulfuric acid hydrolysis followed by continuous ethanol fermentation. To reduce the environmental impact of this process, treatment of the stillage, reuse of the sulfuric acid and reduction of the process water used were studied. The total organic carbon (TOC) concentration of stillage decreased from 29,688 to 269 mg/l by thermophilic methane fermentation followed by aerobic treatment. Washing the solid residue from acid hydrolysis with effluent from the biological treatment increased the sugar recovery from 69.3% to 79.3%. Sulfuric acid recovered during the acid-sugar separation process was condensed and reused for hydrolysis, resulting in a sugar recovery efficiency of 76.8%, compared to 80.1% when fresh sulfuric acid was used. After acetate removal, the condensate could be reused as elution water in the acid-sugar separation process. As much as 86.3% of the process water and 77.6% of the sulfuric acid could be recycled. PMID:23196226

  7. Toxicologic Appraisal of Particulate Matter, Oxides of Sulfur, and Sulfuric Acid

    Microsoft Academic Search

    Mary O. Amdur

    1969-01-01

    An examination of the available toxicological literature indicates that sulfur dioxide itself would be properly classified as a mild respiratory irritant, the main portion of which is absorbed in the upper respiratory tract. The reported industrial experience of symptoms of mild chronic respiratory irritation from exposures at or above 5 ppm is compatible with what would have been predicted on

  8. Elucidating the role of ferrous ion cocatalyst in enhancing dilute acid pretreatment of lignocellulosic biomass

    PubMed Central

    2011-01-01

    Background Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. Results During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe2+ ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe2+ ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe2+ ion pretreatment, in which delamination and fibrillation of the cell wall were observed. Conclusions By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose. PMID:22074910

  9. Quantification of Pantothenic Acid and Folates by Stable Isotope Dilution Assays

    Microsoft Academic Search

    Michael Rychlik; Achim Freisleben

    2002-01-01

    Stable isotope dilution assays for the quantification of pantothenic acid and folates in foods by using four-fold labeled isotopomers of the vitamins as internal standards (IS) were developed. The use of labeled IS enabled to exactly correct losses during cleanup and derivatization.Pantothenic acid and its labeled isotopomer were detected as trimethylsilyl derivatives by gas chromatography–mass spectrometry. In starch a detection

  10. Recovery of dilute acetic acid through esterification in a reactive distillation column

    Microsoft Academic Search

    B. Saha; S. P. Chopade; S. M. Mahajani

    2000-01-01

    The recovery of acetic acid from its dilute aqueous solutions is a major problem in both petrochemical and fine chemical industries. The conventional methods of recovery are azeotropic distillation, simple distillation and liquid–liquid extraction. Physical separations such as distillation and extraction suffer from several drawbacks. The esterification of an aqueous solution (30%) of acetic acid with n-butanol\\/iso-amyl alcohol is a

  11. Monte Carlo Simulations of Small Sulfuric Acid-Water Clusters S. M. Kathmann,* and B. N. Hale,*

    E-print Network

    Hale, Barbara N.

    -to-liquid nucleation1-5 to acid rain formation6-8 and ozone depletion mechanisms.9-11 Doyle's early work2 predictedMonte Carlo Simulations of Small Sulfuric Acid-Water Clusters S. M. Kathmann,* and B. N. Hale§,* En Form: August 7, 2001 Effective atom-atom potentials are developed for binary sulfuric acid

  12. APPLICATION OF AN ELECTROSTATIC PRECIPITATOR FOR INSTRUMENTAL SAMPLING OF SULFURIC ACID

    EPA Science Inventory

    A means of separating gaseous sulfuric acid from flue gas particles has been evaluated. Previous attempts to achieve separation by filtration resulted in retention of the acid by the particulate buildup on the filter surface. A laboratory study of a prototype electrostatic precip...

  13. Heterogeneous freezing of single sulfuric acid solution droplets: laboratory experiments utilizing an acoustic levitator

    Microsoft Academic Search

    M. Ettner; S. K. Mitra; S. Borrmann

    2004-01-01

    The heterogeneous freezing temperatures of single binary sulfuric acid solution droplets were measured in dependency of acid concentration down to temperatures as low as -50°C. In order to avoid influence of supporting substrates on the freezing characteristics, a new technique has been developed to suspend the droplet by means of an acoustic levitator. The droplets contained immersed particles of graphite,

  14. Exogenic controls on sulfuric acid hydrate production at the surface of Europa

    NASA Astrophysics Data System (ADS)

    Dalton, J. B.; Cassidy, T.; Paranicas, C.; Shirley, J. H.; Prockter, L. M.; Kamp, L. W.

    2013-03-01

    External agents have heavily weathered the visible surface of Europa. Internal and external drivers competing to produce the surface we see include, but are not limited to: aqueous alteration of materials within the icy shell, initial emplacement of endogenic material by geologic activity, implantation of exogenic ions and neutrals from Jupiter's magnetosphere, alteration of surface chemistry by radiolysis and photolysis, impact gardening of upper surface layers, and redeposition of sputtered volatiles. Separating the influences of these processes is critical to understanding the surface and subsurface compositions at Europa. Recent investigations have applied cryogenic reflectance spectroscopy to Galileo Near-Infrared Mapping Spectrometer (NIMS) observations to derive abundances of surface materials including water ice, hydrated sulfuric acid, and hydrated sulfate salts. Here we compare derived sulfuric acid hydrate (H2SO4·nH2O) abundance with weathering patterns and intensities associated with charged particles from Jupiter's magnetosphere. We present models of electron energy, ion energy, and sulfur ion number flux as well as the total combined electron and ion energy flux at the surface to estimate the influence of these processes on surface concentrations, as a function of location. We found that correlations exist linking both electron energy flux (r?0.75) and sulfur ion flux (r=0.93) with the observed abundance of sulfuric acid hydrate on Europa. Sulfuric acid hydrate production on Europa appears to be limited in some regions by a reduced availability of sulfur ions, and in others by insufficient levels of electron energy. The energy delivered by sulfur and other ions has a much less significant role. Surface deposits in regions of limited exogenic processing are likely to bear closest resemblance to oceanic composition. These results will assist future efforts to separate the relative influence of endogenic and exogenic sources in establishing the surface composition.

  15. Kinetic Study and Mathematical Model of Hemimorphite Dissolution in Low Sulfuric Acid Solution at High Temperature

    NASA Astrophysics Data System (ADS)

    Xu, Hongsheng; Wei, Chang; Li, Cunxiong; Deng, Zhigan; Li, Minting; Li, Xingbin

    2014-10-01

    The dissolution kinetics of hemimorphite with low sulfuric acid solution was investigated at high temperature. The dissolution rate of zinc was obtained as a function of dissolution time under the experimental conditions where the effects of sulfuric acid concentration, temperature, and particle size were studied. The results showed that zinc extraction increased with an increase in temperature and sulfuric acid concentration and with a decrease in particle size. A mathematical model able to describe the process kinetics was developed from the shrinking core model, considering the change of the sulfuric acid concentration during dissolution. It was found that the dissolution process followed a shrinking core model with "ash" layer diffusion as the main rate-controlling step. This finding was supported with a linear relationship between the apparent rate constant and the reciprocal of squared particle radius. The reaction order with respect to sulfuric acid concentration was determined to be 0.7993. The apparent activation energy for the dissolution process was determined to be 44.9 kJ/mol in the temperature range of 373 K to 413 K (100 °C to 140 °C). Based on the shrinking core model, the following equation was established:

  16. Sequential dilute acid and alkali pretreatment of corn stover: sugar recovery efficiency and structural characterization.

    PubMed

    Lee, Jae Won; Kim, Ji Young; Jang, Hyun Min; Lee, Min Woo; Park, Jong Moon

    2015-04-01

    The objectives of this study were to explore the feasibility of applying sequential dilute acid and alkali pretreatment into the hydrolysis of corn stover and to elucidate the effects of structural changes in the biomass on its enzymatic digestibility. H2SO4 used in the first step selectively hydrolyzed 74.6-77.3% of xylan and NaOH used in the second step removed 85.9-89.4% of lignin, from the raw corn stover. Compared to single dilute acid pretreatment, the proposed combined pretreatment minimized the generation of byproducts such as acetic acid, furfural and hydroxymethylfurfural in the hydrolysates, and enhanced the enzymatic hydrolysis of the solid residue. The changes in the structural features (porosity, morphology, and crystallinity) of the solid residue were strongly correlated with the enhancement of enzymatic digestibility. The overall glucose and xylose yields finally obtained after enzymatic hydrolysis reached 89.1-97.9% and 71.0-75.9%, respectively. PMID:25706555

  17. Removal of arsenious acid from sulfuric acidic solution using ultrasound oxidation and goethite

    NASA Astrophysics Data System (ADS)

    Okawa, Hirokazu; Yoshikawa, Tomohiro; Hosokawa, Ryota; Hangui, Shinji; Kawamura, Youhei; Sugawara, Katsuyasu

    2015-07-01

    We investigated the properties of synthetic goethite for the adsorption of As from strongly acidic solutions in ambient atmosphere under ultrasound irradiation. The goethite was successfully synthesized from iron-containing sulfuric acidic solution (1271 ppm) using an autoclave apparatus for 1 h at 0.12 MPa and 121 °C. The ratio of the iron eluted from the synthetic goethite to the acidic solution was only 0.58% at pH 2.1. Ultrasound irradiation (200 kHz, 200 W) was applied to oxidize 10 ppm of As(III) to As(V) at pH 2.2 for 60 min under various atmospheric conditions. Remarkably, the oxidation ratio of As(III) to As(V) is quite high (89.7%) at pH 2.2 in ambient atmosphere and is close to those obtained for Ar (95.3%) and O2 (95.9%) atmospheres. The As(III) removal ratio reached 94.5% after 60 min of irradiation. Therefore, goethite is a promising material for As adsorption using ultrasound oxidation in the acidic region in ambient atmosphere.

  18. Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

    2003-01-01

    To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

  19. Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

    PubMed

    Suyama, Yuji; Takaku, Satoru; Okawa, Yoshikazu; Matsukubo, Takashi

    2010-01-01

    Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers. PMID:20689238

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

    NASA Astrophysics Data System (ADS)

    Riccobono, F.; Rondo, L.; Sipilä, M.; Barmet, P.; Curtius, J.; Dommen, J.; Ehn, M.; Ehrhart, S.; Kulmala, M.; Kürten, A.; Mikkilä, J.; Petäjä, T.; Weingartner, E.; Baltensperger, U.

    2012-05-01

    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 formation and to the early growth of nucleated particles, respectively. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and ?-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 (?), defined as the ratio between the measured growth rate in the presence of ?-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed ? values indicate that the growth is dominated by organic compounds already at particle diameters of 2 nm. Both the absolute growth rates and ? 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 particles growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. The size resolved growth analysis finally indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

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

    NASA Astrophysics Data System (ADS)

    Riccobono, F.; Rondo, L.; Sipilä, M.; Barmet, P.; Curtius, J.; Dommen, J.; Ehn, M.; Ehrhart, S.; Kulmala, M.; Kürten, A.; Mikkilä, J.; Paasonen, P.; Petäjä, T.; Weingartner, E.; Baltensperger, U.

    2012-10-01

    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 ?-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 (?), defined as the ratio between the measured growth rate in the presence of ?-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed ? values indicate that the growth is already dominated by organic compounds at particle diameters of 2 nm. Both the absolute growth rates and ? 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.

  2. Biomediated Precipitation of Calcium Carbonate and Sulfur in a Faintly Acidic Hot Spring

    NASA Astrophysics Data System (ADS)

    Jiang, L.; Peng, X.; Qiao, H.

    2014-12-01

    A faintly acidic hot spring named "female Tower" (T=73.5 ?, pH=6.64 ) is located in the Jifei Geothermal Field?Yunnan province, Southwest China. The precipitates in the hot spring are composed of large amounts of calcite and sulfur, as reveals by XRD analysis. Scanning electron microscopy (SEM) analysis show the microbial mats are formed of various coccoid, rod and filamentous microbes. Transmission electron microscopy (TEM) analysis show that intracellular sulfur granules are commonly associated with these microbes. Energy dispersive X-ray spectrometer (EDS) analysis shows that the surface of microbes are mainly composed of Ca, C, O and S. A culture-independent molecular phylogenetic analysis demonstrates the majority of bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H2S concentration was up to 60 ppm, while SO42- concentration was only about 10 ppm. We suggest that H2S might be utilized by sulfur-oxidizing bacteria in this hot spring water, leading to the formation of sulfur granules intracellularly and extracellularly. In the meantime, this reaction increases the pH in ambient environments, which fosters the precipitation of calcium carbonate precipitation in the microbial mats. This study suggests that the sulfur-oxidizing bacteria could play an important role in calcium carbonate precipitation in faintly acidic hot spring environments.

  3. Binary diffusion coefficient, partition ratio, and partial molar volume for docosahexaenoic acid, eicosapentaenoic acid and ?-linolenic acid at infinite dilution in supercritical carbon dioxide

    Microsoft Academic Search

    Toshitaka Funazukuri; Chang Yi Kong; Seiichiro Kagei

    2003-01-01

    A tracer response technique with a poly(ethylene glycol) coated capillary column was employed to measure binary diffusion coefficient and partition ratio for the ?3 group of long chain unsaturated fatty acids such as docosahexaenoic acid, eicosapentaenoic acid and ?-linolenic acid at infinite dilution in supercritical (SC) carbon dioxide at temperatures from 308.15 to 343.15K and pressures from 9 to 30MPa.

  4. Process for recovery of sulfur from acid gases

    DOEpatents

    Towler, Gavin P. (Kirkbymoorside, GB2); Lynn, Scott (Pleasant Hill, CA)

    1995-01-01

    Elemental sulfur is recovered from the H.sub.2 S present in gases derived from fossil fuels by heating the H.sub.2 S with CO.sub.2 in a high-temperature reactor in the presence of a catalyst selected as one which enhances the thermal dissociation of H.sub.2 S to H.sub.2 and S.sub.2. The equilibrium of the thermal decomposition of H.sub.2 S is shifted by the equilibration of the water-gas-shift reaction so as to favor elemental sulfur formation. The primary products of the overall reaction are S.sub.2, CO, H.sub.2 and H.sub.2 O. Small amounts of COS, SO.sub.2 and CS.sub.2 may also form. Rapid quenching of the reaction mixture results in a substantial increase in the efficiency of the conversion of H.sub.2 S to elemental sulfur. Plant economy is further advanced by treating the product gases to remove byproduct carbonyl sulfide by hydrolysis, which converts the COS back to CO.sub.2 and H.sub.2 S. Unreacted CO.sub.2 and H.sub.2 S are removed from the product gas and recycled to the reactor, leaving a gas consisting chiefly of H.sub.2 and CO, which has value either as a fuel or as a chemical feedstock and recovers the hydrogen value from the H.sub.2 S.

  5. On the prolonged lifetime of the El Chichon sulfuric acid aerosol cloud

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.

    1987-01-01

    The observed decay of the aerosol mixing ratio following the eruption of El Chichon appears to have been 20-30 percent slower than that following the eruption of Fuego in 1974, even though the sulfuric acid droplets were observed to grow to considerably larger sizes after El Chichon. This suggests the possible presence of a condensation nuclei and sulfuric acid vapor source and continued growth phenomena occurring well after the El Chichon eruption. It is proposed that the source of these nuclei and the associated vapor may be derived from annual evaporation and condensation of aerosol in the high polar regions during stratospheric warming events, with subsequent spreading to lower latitudes.

  6. The bonding strength and corrosion resistance of aluminum alloy by anodizing treatment in a phosphoric acid modified boric acid\\/sulfuric acid bath

    Microsoft Academic Search

    Jin-sheng Zhang; Xu-hui Zhao; Yu Zuo; Jin-ping Xiong

    2008-01-01

    The process of phosphoric\\/boric\\/sulfuric acids anodizing was studied as a new pre-treatment for adhesive bonding of aluminum alloys. The microstructure and topography of the anodic films were examined using SEM and AFM, and the adhesive strength and corrosion behavior were studied with lap-shear test, wedge test and electrochemical technology. The results showed that by the process of phosphoric\\/boric\\/sulfuric acids anodizing

  7. Uptake of HCl molecules by aqueous sulfuric acid droplets as a function of acid concentration

    NASA Astrophysics Data System (ADS)

    Watson, Lyn R.; van Doren, Jane M.; Davidovits, Paul; Worsnop, Douglas R.; Zahniser, Mark S.; Kolb, Charles E.

    1990-04-01

    The uptake of HCl molecules by aqueous sulfuric acid droplets was measured at 283 K as a function of acid mole fraction. In the apparatus a controllable stream of monodispersed droplets is produced by a vibrating orifice jet. The droplets enter a flow system containing HCl(g). The droplets are switched on and off while the density of the species is continuously monitored by infrared absorption. From the on-off signal a coefficient for the probability of gas uptake upon collision with the liquid surface is calculated. This coefficient is 0.15 for pure water, remains constant up to 0.1 mole fraction of H2SO4 (40 wt %) and then drops sharply to <10-2 at 0.2 mole fraction (60 wt %). The results are in accord with calculations based on the decrease in the solubility of HCl with increasing H2SO4 mole fraction. Increasing acidity reduces the dissociation of HCl into H+ and Cl- in solution. Our results indicate that mass accommodation coefficients are large enough so that the HCl content of stratospheric aerosols will be determined entirely by this solubility.

  8. J. Chem. Soc., Perkin Trans. 2, 1997 821 Mechanism of the Beckmann rearrangement in sulfuric acid solution

    E-print Network

    Nguyen, Minh Tho

    a Beckmann mixture consists of a solution of acetic acid and acetic anhydride, saturated with gaseous hydrogen chloride, an oleum solution contains sulfuric acid and sulfur trioxide (H2SO4 SO3). An aqueous aqueous solutions of H2SO4, alicyclic oximes undergo hydrolysis rather than BR. In the industrial

  9. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  10. Microwave-assisted digestion procedures for biological samples with diluted nitric acid: identification of reaction products.

    PubMed

    Gonzalez, Mįrio H; Souza, Gilberto B; Oliveira, Regina V; Forato, Lucimara A; Nóbrega, Joaquim A; Nogueira, Ana Rita A

    2009-07-15

    Microwave-assisted sample preparation using diluted nitric acid solutions is an alternative procedure for digesting organic samples. The efficiency of this procedure depends on the chemical properties of the samples and in this work it was evaluated by the determination of crude protein amount, fat and original carbon. Soybeans grains, bovine blood, bovine muscle and bovine viscera were digested in a cavity-microwave oven using oxidant mixtures in different acid concentrations. The digestion efficiency was evaluated based on the determination of residual carbon content and element recoveries using inductively coupled plasma optical emission spectrometry (ICP OES). In order to determine the main residual organic compounds, the digests were characterized by nuclear magnetic resonance ((1)H NMR). Subsequently, studies concerning separation of nitrobenzoic acid isomers were performed by ion pair reversed phase liquid chromatography using a C18 stationary phase, water:acetonitrile:methanol (75:20:5, v/v/v)+0.05% (v/v) TFA as mobile phase and ultraviolet detection at 254 nm. Sample preparation based on diluted acids proved to be feasible and a recommendable alternative for organic sample digestion, reducing both the reagent volumes and the variability of the residues as a result of the process of decomposition. It was shown that biological matrices containing amino acids, proteins and lipids in their composition produced nitrobenzoic acid isomers and other organic compounds after cleavage of chemical bonds. PMID:19559896

  11. Helically agitated mixing in dry dilute acid pretreatment enhances the bioconversion of corn stover into ethanol

    PubMed Central

    2014-01-01

    Background Dry dilute acid pretreatment at extremely high solids loading of lignocellulose materials demonstrated promising advantages of no waste water generation, less sugar loss, and low steam consumption while maintaining high hydrolysis yield. However, the routine pretreatment reactor without mixing apparatus was found not suitable for dry pretreatment operation because of poor mixing and mass transfer. In this study, helically agitated mixing was introduced into the dry dilute acid pretreatment of corn stover and its effect on pretreatment efficiency, inhibitor generation, sugar production, and bioconversion efficiency through simultaneous saccharification and ethanol fermentation (SSF) were evaluated. Results The overall cellulose conversion taking account of cellulose loss in pretreatment was used to evaluate the efficiency of pretreatment. The two-phase computational fluid dynamics (CFD) model on dry pretreatment was established and applied to analyze the mixing mechanism. The results showed that the pretreatment efficiency was significantly improved and the inhibitor generation was reduced by the helically agitated mixing, compared to the dry pretreatment without mixing: the ethanol titer and yield from cellulose in the SSF reached 56.20 g/L and 69.43% at the 30% solids loading and 15 FPU/DM cellulase dosage, respectively, corresponding to a 26.5% increase in ethanol titer and 17.2% increase in ethanol yield at the same fermentation conditions. Conclusions The advantage of helically agitated mixing may provide a prototype of dry dilute acid pretreatment processing for future commercial-scale production of cellulosic ethanol. PMID:24387051

  12. OPERATION OF A SULFURIC ACID PLANT USING BLENDED COPPER SMELTER GASES

    EPA Science Inventory

    A high degree of control of SOx emissions at copper smelters can be obtained by blending reverberatory furnace gases with gases from roasters and converters and using the combined stream as feed to a sulfuric acid plant. The Bor Copper Smelter in Bor, Yugoslavia, experimented wit...

  13. Kinetics of sulfuric acid leaching of cadmium from Cd–Ni zinc plant residues

    Microsoft Academic Search

    Mohammad Sadegh Safarzadeh; Davood Moradkhani; Mehdi Ojaghi-Ilkhchi

    2009-01-01

    Cd–Ni filtercakes are produced continuously at the third purification step in the electrolytic production of zinc in the National Iranian Lead and Zinc Company (NILZ) in northwestern Iran. In this research, the dissolution kinetics of cadmium from Cd–Ni residues produced in NILZ plant has been investigated. Hence, the effects of temperature, sulfuric acid concentration, particle size and stirring speed on

  14. A tunable diode laser stack monitor for sulfuric acid vapor. Final report Sep 78Mar 80

    Microsoft Academic Search

    E. F. Pearson; A. W. Mantz

    1979-01-01

    A field prototype instrument for continuous in-situ monitoring of sulfuric acid vapor in industrial smoke stacks has been developed. The method of detection is dual wavelength differential absorption in the infrared. Two tunable diode lasers are locked to two specific frequencies that provide analytical and background absorption information. The difference between the analytical and background absorption yields the net absorption

  15. Mechanism and kinetics of aluminum and iron leaching from coal fly ash by sulfuric acid

    Microsoft Academic Search

    A. Seidel; Y. Zimmels

    1998-01-01

    The mechanism and kinetics of leaching of aluminum and iron from Coal Fly Ash (CFA), by sulfuric acid, involves a rate controlling step of mass transfer. It is shown that, in the leaching process, particles follow the shrinking core model with respect to formation of unreacted core that is encapsulated by a leached, porous, layer. Formation of diffusion resistant calcium

  16. MORPHOLOGICAL EFFECTS OF PROLONGED EXPOSURE TO OZONE AND SULFURIC ACID AEROSOL ON THE RAT LUNG

    EPA Science Inventory

    The purpose of this study was to determine the pulmonary effects of a combination of ozone (0.5 ppm) and sulfuric acid aerosol (1 mg/cu. m.) and to assess the possibility of interactive effects. Groups of Sprague-Dawley rats were continously exposed to the pollutants, either indi...

  17. BIOCHEMICAL CHANGES IN HUMANS UPON EXPOSURE TO SULFURIC ACID AEROSOL AND EXERCISE

    EPA Science Inventory

    A total of 18 human subjects were exposed to ambient air for four hours on the first day of exposure and to four hours of 100 micrograms/cu. m. (0.033 micromole) sulfuric acid aerosol exposed to four hours of ambient air on both exposure days. Six biochemical blood parameters wer...

  18. The role of cluster energy nonaccommodation in atmospheric sulfuric acid nucleation.

    PubMed

    Kurtén, Theo; Kuang, Chongai; Gómez, Pedro; McMurry, Peter H; Vehkamäki, Hanna; Ortega, Ismael; Noppel, Madis; Kulmala, Markku

    2010-01-14

    We discuss the possible role of energy nonaccommodation (monomer-cluster collisions that do not result in stable product formation due to liberated excess energy) in atmospheric nucleation processes involving sulfuric acid. Qualitative estimates of the role of nonaccommodation are computed using quantum Rice-Ramsberger-Kassel theory together with quantum chemically calculated vibrational frequencies and anharmonic coupling constants for small sulfuric acid-containing clusters. We find that energy nonaccommodation effects may, at most, decrease the net formation rate of sulfuric acid dimers by up to a factor of 10 with respect to the hard-sphere collision rate. A decrease in energy nonaccommodation due to an increasing number of internal degrees of freedom may kinetically slightly favor the participation of amines rather than ammonia as stabilizing agents in sulfuric acid nucleation, though the kinetic enhancement factor is likely to be less than three. However, hydration of the clusters (which always occurs in ambient conditions) is likely to increase the energy accommodation factor, reducing the role that energy nonaccommodation plays in atmospheric nucleation. PMID:20095671

  19. A comparative study of electrochemical behavior of chalcopyrite, chalcocite and bornite in sulfuric acid solution

    Microsoft Academic Search

    Elsa M Arce; Ignacio Gonzįlez

    2002-01-01

    A comparative study of the electrochemical behavior of different copper sulfide minerals (chalcopyrite, bornite and chalcocite) in sulfuric acid solutions was performed. Carbon paste electrodes (CPE) containing mineral particles with nonconducting binder were used. The comparative study shows that the chalcopyrite oxidation process does not produce covellite as claimed by some authors. Chalcopyrite oxidation has been found to produce a

  20. Response of DOC in acid-sensitive Maine lakes to decreasing sulfur deposition (1993 - 2009)

    EPA Science Inventory

    In response to the Clean Air Act Amendments of 1990, sulfur deposition has decreased across the northeastern United States. As a result, sulfate concentrations in lakes and streams have also decreased and many surface waters have become less acidic. Over the same time period, th...

  1. Biogeochemistry of Iron and Sulfur in Sediments of an Acidic Mining Lake in Lusatia, Germany

    Microsoft Academic Search

    K. Friese; K. Wendt-Potthoff; D. W. Zachmann; A. Fauville; B. Mayer; J. Veizer

    1998-01-01

    Chemical, microbiological and stable isotope analyses of sediments from an acidic mining lake were used to evaluate whether biogeochemical processes, such as iron and sulfate reduction, are extant, because such processes can potentially generate alkalinity. Sediment cores were sliced in cm intervals to achieve a high resolution for spatial distribution of organic and inorganic components. Iron, sulfur, carbon, nitrogen and

  2. A theoretical study of temperature dependence of cluster formation from sulfuric acid and ammonia

    E-print Network

    Lee, Shan-Hu

    a b s t r a c t We have performed density functional theory (BL3YP) and ab initio (MP2) calculations [10]. Molecular modeling studies with density functional theories (DFT) and ab initio calculationsA theoretical study of temperature dependence of cluster formation from sulfuric acid and ammonia

  3. EFFECTS OF SULFURIC ACID RAIN ON TWO MODEL HARDWOOD FORESTS: THROUGHFALL, LITTER LEACHATE, AND SOIL SOLUTION

    EPA Science Inventory

    Simulated sulfuric acid rain (pH 3.0, 3.5, 4.5, and 5.6) was applied to model forests containing either sugar maple (Acer saccharum) or red alder (Alnus rubra). Water samples were collected above and below the canopy, below the litter, and from 20 cm and 1 m below the surface of ...

  4. Interfacial Behavior of Cysteine between Mild Steel and Sulfuric Acid as Corrosion Inhibitor

    Microsoft Academic Search

    Muzaffer Özcan; Faruk Karada?; Ilyas Dehri

    2008-01-01

    Interfacial behavior of cysteine (Cys) between mild steel and sulfuric acid solution as a corrosion inhibitor has been studied with electrochemical AC (alternating current) and DC (direct current) techniques at (25.0±0.1) °C. The AC impedance results were evaluated using equivalent circuits in which a constant phase element (CPE) has been replaced with double layer capacitance (Cdl) to represent the frequency

  5. Effective Diffusion Coefficients for Methanol in Sulfuric Acid Solutions Measured by Raman Spectroscopy

    E-print Network

    -resolved Raman scattering measurements to determine composition-dependent binary diffusion coefficientsEffective Diffusion Coefficients for Methanol in Sulfuric Acid Solutions Measured by Raman 17, 2008; ReVised Manuscript ReceiVed: August 17, 2008 The diffusion of methanol into 0-96.5 wt

  6. Use of nonionic surfactant to reduce sulfuric acid mist in the copper electrowinning process

    Microsoft Academic Search

    Jennifer L. Sigley; Paul C. Johnson; Stephen P. Beaudoin

    2003-01-01

    During the copper electrowinning process, sulfuric acid mist is released into the air above the electrowinning tanks. This mist causes health problems for the operators in the electrowinning plant. Therefore, the Occupational Safety and Health Administration (OSHA) has mandated that electrowinning tanks comply with new stringent regulations. This has sparked an interest by copper mines to develop new techniques to

  7. BIOCHEMICAL EFFECTS OF INHALATION OF SULFURIC ACID MIST BY HUMAN SUBJECTS WHILE AT REST

    EPA Science Inventory

    A total of 20 human subjects were exposed to 100 micrograms/cu m (0.033 uM) sulfuric acid aerosol (0.5 micrometers mean mass diameter) for four hours per day for two consecutive days. A total of 17 human subjects were exposed to four hours of ambient air on both exposure days. Th...

  8. Uptake of HCl and HOCl onto sulfuric acid. Solubilities, diffusivities, and reaction

    SciTech Connect

    Hanson, D.R.; Ravishankara, A.R. (NOAA Aeronomy Lab., Boulder, CO (United States) Univ. of Colorado, Boulder, CO (United States))

    1993-11-25

    The interaction of HOCl and HCl vapors with liquid sulfuric acid surfaces was studied in a flow tube equipped with chemical ionization mass spectrometry detection. Time-dependent uptake of HCl and HOCl was measured. A methodology for deriving the value of the quantity H[radical]D[sub 1], (the product of the Henry's law coefficient and the square root of the liquid-phase diffusion coefficient) is discussed. The partial pressures of HCl over HCl-doped sulfuric acid solutions were also measured to directly determine H for HCl (H[sub HCl]*). Using the measured values of H[sub HCl]* and H[sub HCl]*[radical]D[sub 1], the value of D[sub 1] for HCl in 50 wt % sulfuric acid was extracted. Values for H[sub HOCl] and for the second-order rate coefficient for the reaction between dissolved HOCl and HCl were also obtained. The application of these results to modeling stratospheric heterogeneous processes in sulfuric acid aerosols is discussed. 31 refs., 14 refs., 3 tabs.

  9. Use of N?amino acid isotope dilution techniques to determine endogenous amino acids in ileal digesta in growing pigs

    Microsoft Academic Search

    Vince M. Gabert; Nuria Canibe; Henry Jųrgensen; Bjųrn O. Eggum; Willem C. Sauer

    1997-01-01

    An experiment was carried out to determine the contribution of endogenous amino acids (AA) to total AA, using the N?AA and N?leucine isotope dilution techniques, in ileal digesta from growing pigs. Four barrows, initial body weight (BW) 33.8 ± 1.0 kg, were fitted with a simple T?cannula at the distal ileum and one catheter in each of the external jugular

  10. Study of insoluble crystals derived from solutions of Kevlar 49 in sulfuric acid

    SciTech Connect

    Butler, N.L.

    1984-05-21

    The object of the study was to isolate and obtain x-ray diffraction analysis of the insoluble crystals which have been observed in Kevlar 49/H/sub 2/SO/sub 4/ dope. These insoluble crystals had previously been reported to be Kevlar single crystals after analysis by optical microscopy. A more detailed analysis does not support this conclusion. Additional optical microscopy coupled with FTIR and elemental analysis for C, H and N, has shown that these insoluble crystals are in fact terephthalic acid which is a decomposition product of the acid hydrolysis of Kevlar. A model compound study of sulfuric-acid hydrolysis of aromatic amide was carried out in order to better understand the sulfuric-acid-hydrolysis of Kevlar.

  11. Sulfur amino acid metabolism in doxorubicin-resistant breast cancer cells

    SciTech Connect

    Ryu, Chang Seon; Kwak, Hui Chan; Lee, Kye Sook [College of Pharmacy and RCTCP, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kang, Keon Wook [BK21 Project Team and Department of Pharmacy, College of Pharmacy,Chosun University, Gwangju 501-759 (Korea, Republic of); Oh, Soo Jin; Lee, Ki Ho; Kim, Hwan Mook [Bio-Evaluation Center, KRIBB, Ochang, Chungbuk (Korea, Republic of); Ma, Jin Yeul [Center for Herbal Medicine Improvement Research, Korea Institute of Oriental medicine, Daejeon 305-811 (Korea, Republic of); Kim, Sang Kyum, E-mail: sangkim@cnu.ac.kr [College of Pharmacy and RCTCP, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2011-08-15

    Although methionine dependency is a phenotypic characteristic of tumor cells, it remains to be determined whether changes in sulfur amino acid metabolism occur in cancer cells resistant to chemotherapeutic medications. We compared expression/activity of sulfur amino acid metabolizing enzymes and cellular levels of sulfur amino acids and their metabolites between normal MCF-7 cells and doxorubicin-resistant MCF-7 (MCF-7/Adr) cells. The S-adenosylmethionine/S-adenosylhomocysteine ratio, an index of transmethylation potential, in MCF-7/Adr cells decreased to {approx} 10% relative to that in MCF-7 cells, which may have resulted from down-regulation of S-adenosylhomocysteine hydrolase. Expression of homocysteine-clearing enzymes, such as cystathionine beta-synthase, methionine synthase/methylene tetrahydrofolate reductase, and betaine homocysteine methyltransferase, was up-regulated in MCF-7/Adr cells, suggesting that acquiring doxorubicin resistance attenuated methionine-dependence and activated transsulfuration from methionine to cysteine. Homocysteine was similar, which is associated with a balance between the increased expressions of homocysteine-clearing enzymes and decreased extracellular homocysteine. Despite an elevation in cysteine, cellular GSH decreased in MCF-7/Adr cells, which was attributed to over-efflux of GSH into the medium and down-regulation of the GSH synthesis enzyme. Consequently, MCF-7/Adr cells were more sensitive to the oxidative stress induced by bleomycin and menadione than MCF-7 cells. In conclusion, our results suggest that regulating sulfur amino acid metabolism may be a possible therapeutic target for chemoresistant cancer cells. These results warrant further investigations to determine the role of sulfur amino acid metabolism in acquiring anticancer drug resistance in cancer cells using chemical and biological regulators involved in sulfur amino acid metabolism. - Research Highlights: > MCF-7/Adr cells showed decreases in cellular GSH, which were attributed to increase efflux of GSH. > MCF-7/Adr was more sensitive to oxidative stress induced by bleomycin and menadione. > Hcy-clearing enzymes involved in were up-regulated in MCF-7/Adr cells. > Doxorubicin-resistance attenuated Met-dependence and activated transsulfuration. > Regulating sulfur amino acid metabolism may be a possible therapeutic target.

  12. Sudden substrate dilution induces a higher rate of citric acid production by Aspergillus niger.

    PubMed Central

    Legisa, M; Gradisnik-Grapulin, M

    1995-01-01

    On the basis of the present knowledge of Aspergillus niger metabolism during citric acid fermentation, an idea on how to improve the process was formed. Initially, a higher sucrose concentration was used for the germination of spores, which caused a higher intracellular level of the osmoregulator, glycerol, to be present. When citric acid started to be excreted into the medium, the substrate was suddenly diluted. Optimization of this procedure resulted in a nearly tripled volumetric rate (grams per liter per hour) of acid production, while the overall fermentation time was halved compared with the usual batch process. Yet, a characteristic delay was observed at the start of the acid excretion after the dilution. Hypo-osmotic shock caused a prominent elevation of intracellular cyclic AMP levels. Simultaneously, the specific activity of 6-phosphofructo-1-kinase increased significantly, probably due to phosphorylation of the protein molecule by cyclic AMP-dependent protein kinase. Specific 6-phosphofructo-1-kinase activity was much higher in the treated than in the normally growing mycelium. The metabolic flow through glycolysis was expected to be higher, which should contribute to a higher volumetric rate of acid production. PMID:7618885

  13. Revealing biogenic sulfuric acid corrosion in sludge digesters: detection of sulfur-oxidizing bacteria within full-scale digesters.

    PubMed

    Huber, B; Drewes, J E; Lin, K C; König, R; Müller, E

    2014-01-01

    Biogenic sulfuric acid corrosion (BSA) is a costly problem affecting both sewerage infrastructure and sludge handling facilities such as digesters. The aim of this study was to verify BSA in full-scale digesters by identifying the microorganisms involved in the concrete corrosion process, that is, sulfate-reducing (SRB) and sulfur-oxidizing bacteria (SOB). To investigate the SRB and SOB communities, digester sludge and biofilm samples were collected. SRB diversity within digester sludge was studied by applying polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the dsrB-gene (dissimilatory sulfite reductase beta subunit). To reveal SOB diversity, cultivation dependent and independent techniques were applied. The SRB diversity studies revealed different uncultured SRB, confirming SRB activity and H2S production. Comparable DGGE profiles were obtained from the different sludges, demonstrating the presence of similar SRB species. By cultivation, three pure SOB strains from the digester headspace were obtained including Acidithiobacillus thiooxidans, Thiomonas intermedia and Thiomonas perometabolis. These organisms were also detected with PCR-DGGE in addition to two new SOB: Thiobacillus thioparus and Paracoccus solventivorans. The SRB and SOB responsible for BSA were identified within five different digesters, demonstrating that BSA is a problem occurring not only in sewer systems but also in sludge digesters. In addition, the presence of different SOB species was successfully associated with the progression of microbial corrosion. PMID:25353947

  14. Boric\\/Sulfuric Acid Anodizing of Aluminum Alloys 2024 and 7075: Film Growth and Corrosion Resistance

    Microsoft Academic Search

    G. E. Thompson; C. J. E. Smith; P. E. Skeldon; L. E. Zhang

    1999-01-01

    The influence of boric acid (HāBOā) additions to sulfuric acid (HāSOā) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (NaāCrāOā)\\/HāSOā (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of HāBOā to 50 g\\/L. Pretreatments affected

  15. Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298.15 K

    SciTech Connect

    Hovey, J.K.; Pitzer, K.S. [Lawrence Berkeley Lab., CA (United States); Rard, J.A. [Lawrence Livermore National Lab., CA (United States)

    1991-07-01

    New isopiestic vapor-pressure measurements on the aqueous system {l_brace}(1{minus}y)H{sub 2}SO{sub 4}+yNA{sub 2}SO{sub 4}{r_brace} along with earlier experimental investigations that span the range from y=0 to y=1 and infinitely dilute to supersaturated molalities have been analyzed in terms of the Pitzer ion-interaction model. Refined ion-interaction parameters for aqueous sodium sulfate valid over the temperature range 273 K to 373 K have been calculated and used for analyzing results for mixtures containing sulfuric acid and sodium sulfate at 298.15 K. Analysis of experimental results for these aqueous mixtures required explicit consideration of the dissociation reaction of bisulfate ion. Previous treatments of aqueous sulfuric acid and subsequently the bisulfate dissociation equilibrium valid in the range 273 K to 343 K were employed as a first approximation in representing the mixed solutions. Two sets of Pitzer ion-interaction parameters are presented for (sodium sulfate + sulfuric acid). The validity of the first set is limited in ionic strength and molality to saturated solutions of pure aqueous sodium sulfate (4 mol{center_dot}kg{sup {minus}1}). The second set of parameters corresponds to a slightly less precise representation but is valid over the entire range of experimental results considered. Both sets of parameters provide a more complete description of pure sulfuric acid solutions because of the removal of various redundancies of ion-interaction parameters. The specific ion-interaction terms used and the overall fitting procedure are described as well as selected examples of relevant thermodynamic calculations in the mixed system Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O. 33 refs., 6 figs., 5 tabs.

  16. Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298. 15 K

    SciTech Connect

    Hovey, J.K.; Pitzer, K.S. (Lawrence Berkeley Lab., CA (United States)); Rard, J.A. (Lawrence Livermore National Lab., CA (United States))

    1991-07-01

    New isopiestic vapor-pressure measurements on the aqueous system {l brace}(1{minus}y)H{sub 2}SO{sub 4}+yNA{sub 2}SO{sub 4}{r brace} along with earlier experimental investigations that span the range from y=0 to y=1 and infinitely dilute to supersaturated molalities have been analyzed in terms of the Pitzer ion-interaction model. Refined ion-interaction parameters for aqueous sodium sulfate valid over the temperature range 273 K to 373 K have been calculated and used for analyzing results for mixtures containing sulfuric acid and sodium sulfate at 298.15 K. Analysis of experimental results for these aqueous mixtures required explicit consideration of the dissociation reaction of bisulfate ion. Previous treatments of aqueous sulfuric acid and subsequently the bisulfate dissociation equilibrium valid in the range 273 K to 343 K were employed as a first approximation in representing the mixed solutions. Two sets of Pitzer ion-interaction parameters are presented for (sodium sulfate + sulfuric acid). The validity of the first set is limited in ionic strength and molality to saturated solutions of pure aqueous sodium sulfate (4 mol{center dot}kg{sup {minus}1}). The second set of parameters corresponds to a slightly less precise representation but is valid over the entire range of experimental results considered. Both sets of parameters provide a more complete description of pure sulfuric acid solutions because of the removal of various redundancies of ion-interaction parameters. The specific ion-interaction terms used and the overall fitting procedure are described as well as selected examples of relevant thermodynamic calculations in the mixed system Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O. 33 refs., 6 figs., 5 tabs.

  17. Synergistic extraction of rare earth by mixtures of 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester and di-(2-ethylhexyl) phosphoric acid from sulfuric acid medium

    Microsoft Academic Search

    Xiaowei HUANG; Jianning LI; Zhiqi LONG; Yongqi ZHANG; Xiangxin XUE; Zhaowu ZHU

    2008-01-01

    The extraction of Nd3+ and Sm3+, including the extraction and stripping capability as well as the separation effect of Nd3+ or Sm3+, from a sulfuric acid medium, by mixtures of di-(2-ethylhexyl) phosphoric acid (HDEHP, H2A2(0)) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (HEH\\/EHP, H2L2(0)) were studied. The distribution ratios and synergistic coefficients of Nd3+ and Sm3+ in different acidities were also

  18. Delayed production of sulfuric acid condensation nuclei in the polar stratosphere from El Chichon volcanic vapors

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.; Gringel, W.

    1985-01-01

    It is pointed out that measurements of the vertical profiles of atmospheric condensation nuclei (CN) have been conducted since 1973. Studies with a new instrument revealed that the CN concentration undergoes a remarkable annual variation in the 30-km region characterized by a large increase in the late winter/early spring period with a subsequent decay during the remainder of the year. The event particles are observed to be volatile at 150 C, suggesting a sulfuric acid-water composition similar to that found in the normal 20 km aerosol layer. The development of about 10 to the 7th metric tons of sulfuric acid aerosol following the injection of sulfurous gases by El Chichon in April 1982, prompted Hofmann and Rosen (1983) to predict a very large CN event for 1983. The present investigation is concerned with the actual observation of the predicted event. Attention is given to the observation of a very large increase of what appear to be small sulfuric acid droplets at 30-km altitude in January 1983 over Laramie, WY, in January 1983.

  19. A combined proteomic and transcriptomic analysis on sulfur metabolism pathways of Arabidopsis thaliana under simulated acid rain.

    PubMed

    Liu, Tingwu; Chen, Juan A; Wang, Wenhua; Simon, Martin; Wu, Feihua; Hu, Wenjun; Chen, Juan B; Zheng, Hailei

    2014-01-01

    With rapid economic development, most regions in southern China have suffered acid rain (AR) pollution. In our study, we analyzed the changes in sulfur metabolism in Arabidopsis under simulated AR stress which provide one of the first case studies, in which the systematic responses in sulfur metabolism were characterized by high-throughput methods at different levels including proteomic, genomic and physiological approaches. Generally, we found that all of the processes related to sulfur metabolism responded to AR stress, including sulfur uptake, activation and also synthesis of sulfur-containing amino acid and other secondary metabolites. Finally, we provided a catalogue of the detected sulfur metabolic changes and reconstructed the coordinating network of their mutual influences. This study can help us to understand the mechanisms of plants to adapt to AR stress. PMID:24595051

  20. Effect of dikes and sulfuric acid on cotton under effluent irrigation

    SciTech Connect

    Oron, G.; DeMalach, Y. (Ben-Gurion Univ. of the Negev, Sde Boker (Israel))

    1989-06-01

    Extensive efforts are being undertaken to improve effluent use in arid zones with alkaline soils. In Israel, this type of soil (loess), with a relatively large amount of water loss due to runoff generation, is mainly found in the south. The possibility of decreasing runoff, soil erosion, improving water intake rate, and obtaining economic cotton yields was examined in a series of field experiments. Various combinations of dike construction between cotton rows and sulfuric acid applications were examined. Results showed that sulfuric acid significantly reduced runoff reduction and improved water infiltration, and that the acid treatments improves water intake and cotton yield more significantly than that of the dikes, under sprinkler and trickle irrigation systems.

  1. The loss of CF2O on ice, NAT, and sulfuric acid solutions

    NASA Astrophysics Data System (ADS)

    Hanson, D. R.; Ravishankara, A. R.

    1991-09-01

    We measured the first-order loss rate coefficients for CF2O on solid surfaces, ice and HNO3-treated ice, and on sulfuric acid solutions that coated the inside wall of a flow tube. We determined an upper limit for the uptake coefficient, ?, of ˜3×10-6 for CF2O on ice and HNO3-treated ice. A value for ? on a 60% (by weight) sulfuric acid solution of 3(+2/-3)× 10-6 was measured and we observed a higher value over 40% acid, ? = 6×10-5 (± 30%). The loss of CF2O on stratospheric particles is a very slow process and will be insignificant for events that occur on timescales of a year, such as the annual polar chlorine activation phenomena.

  2. Solubility of methanol in low-temperature aqueous sulfuric acid and implications for atmospheric particle composition

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Using traditional Knudsen cell techniques, we find well-behaved Henry's law uptake of methanol in aqueous 45 - 70 wt% H2SO4 solutions at temperatures between 197 and 231 K. Solubility of methanol increases with decreasing temperature and increasing acidity, with an effective Henry's law coefficient ranging from 10(exp 5) - 10(exp 8) M/atm. Equilibrium uptake of methanol into sulfuric acid aerosol particles in the upper troposphere and lower stratosphere will not appreciably alter gas-phase concentrations of methanol. The observed room temperature reaction between methanol and sulfuric acid is too slow to provide a sink for gaseous methanol at the temperatures of the upper troposphere and lower stratosphere. It is also too slow to produce sufficient quantities of soluble reaction products to explain the large amount of unidentified organic material seen in particles of the upper troposphere.

  3. Heterogeneous chemistry of acetone in sulfuric acid solutions: Implications for the upper troposphere

    SciTech Connect

    Kane, S.M.; Timonen, R.S.; Leu, M.T.

    1999-11-18

    The uptake of acetone vapor by liquid sulfuric acid has been investigated over the range of 40--87 wt % H{sub 2}SO{sub 4} and between the temperatures 198 and 300 K. Studies were performed with a flow-tube reactor, using a quadrupole mass spectrometer for detection. At most concentrations studied (40--75 wt %), acetone was physically absorbed by sulfuric acid without undergoing irreversible reaction. However, at acid concentrations at or above 80 wt %, reactive uptake of acetone was observed, leading to products such as mesityl oxide and/or mesitylene. From time-dependent uptake data and liquid-phase diffusion coefficients calculated from molecular viscosity, the effective Henry's law solubility constant (H*) was determined. The solubility of acetone in liquid sulfuric acid was found to increase with increasing acid concentration and decreasing temperature. In the 75 wt % and 230 K range, the value for H* was found to be {approximately}2 x 10{sup 6} M/atm. This value suggests that acetone primarily remains in the gas phase rather than absorbing into sulfate aerosols under atmospheric conditions.

  4. EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVEHIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

    SciTech Connect

    Ketusky, E

    2008-07-11

    At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With the chemical thermodynamic equilibrium based software results showing that 1 wt% oxalic acid could theoretically work, simulant dissolution testing was initiated. For the dissolution testing, existing simulant was obtained, and an approximate 20 liter test rig was built. Multiple batch dissolutions of both wet and air-dried simulant were performed. Overall, the testing showed that dilute oxalic acid dissolved a greater fraction of the stimulant and resulted in a significantly larger acid effectiveness (i.e., grams of sludge dissolved/mole of acid) than the baseline technology. With the potential effectiveness confirmed via simulant testing, additional testing, including radioactive sludge testing, is planned.

  5. Kinetic and Modeling Investigation to Provide Design Guidelines for the NREL Dilute-Acid Process Aimed at Total Hydrolysis/Fractionation of Lignocellulosic Biomass: July 1998

    SciTech Connect

    Lee, Y. Y.; Iyer, P.; Xiang, Q.; Hayes, J.

    2004-08-01

    Following up on previous work, subcontractor investigated three aspects of using NREL ''pretreatment'' technology for total hydrolysis (cellulose as well as hemicellulose) of biomass. Whereas historic hydrolysis of biomass used either dilute acid or concentrated acid technology for hydrolysis of both hemicellulose and cellulose, NREL has been pursuing very dilute acid hydrolysis of hemicellulose followed by enzymatic hydrolysis of cellulose. NREL's countercurrent shrinking-bed reactor design for hemicellulose hydrolysis (pretreatment) has, however, shown promise for total hydrolysis. For the first task, subcontractor developed a mathematical model of the countercurrent shrinking bed reactor operation and, using yellow poplar sawdust as a feedstock, analyzed the effect of: initial solid feeding rate, temperature, acid concentration, acid flow rate, Peclet number (a measure of backmixing in liquid flow), and bed shrinking. For the second task, subcontractor used laboratory trials, with yellow poplar sawdust and 0.07 wt% sulfuric acid at various temperatures, to verify the hydrolysis of cellulose to glucose (desired) and decomposition of glucose (undesired) and determine appropriate parameters for use in kinetic models. Unlike cellulose and hemicellulose, lignins, the third major component of biomass, are not carbohydrates that can be broken down into component sugars. They are, however, aromatic complex amorphous phenolic polymers that can likely be converted into low-molecular weight compounds suitable for production of fuels and chemicals. Oxidative degradation is one pathway for such conversion and hydrogen peroxide would be an attractive reagent for this, as it would leave no residuals. For the third task, subcontractor reacted lignin with hydrogen peroxide under various conditions and analyzed the resulting product mix.

  6. Particle size distributions in Arctic polar stratospheric clouds, growth and freezing of sulfuric acid droplets, and implications for cloud formation

    NASA Technical Reports Server (NTRS)

    Dye, James E.; Baumgardner, D.; Gandrud, B. W.; Kawa, S. R.; Kelly, K. K.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Gary, B. L.

    1992-01-01

    The paper uses particle size and volume measurements obtained with the forward scattering spectrometer probe model 300 during January and February 1989 in the Airborne Arctic Stratospheric Experiment to investigate processes important in the formation and growth of polar stratospheric cloud (PSC) particles. It is suggested on the basis of comparisons of the observations with expected sulfuric acid droplet deliquescence that in the Arctic a major fraction of the sulfuric acid droplets remain liquid until temperatures at least as low as 193 K. It is proposed that homogeneous freezing of the sulfuric acid droplets might occur near 190 K and might play a role in the formation of PSCs.

  7. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    SciTech Connect

    Soleimani, Sahar, E-mail: ssoleima@connect.carleton.ca; Isgor, O. Burkan, E-mail: burkan_isgor@carleton.ca; Ormeci, Banu, E-mail: banu_ormeci@carleton.ca

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5? biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ? 30 ?m before acidification to ? 60 ?m after acidification. These results demonstrated that E. coli DH5? biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5? biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  8. Mineralogical Controls on Microbial Diversity in a Sulfuric Acid Karst System

    NASA Astrophysics Data System (ADS)

    Jones, A. A.; Bennett, P.

    2011-12-01

    The role mineralogy plays on microbial community distribution, composition, niche differentiation, and accumulation is a complex and nebulous association. Microbial phylogenetic diversity and bacterial composition of communities obtained from Lower Kane Cave (LKC), WY, USA, were studied using next generation bacterial 16S rRNA sequencing techniques. The microbial consortium found within LKC was found to be primarily composed of neutrophilic sulfur-oxidizing members of the gamma- and epsilon-proteobacteria . The microbial population within LKC has been instigated in previous studies to have a significant role in the processes of sulfuric acid speleogenesis. Using a LKC biomat as the inoculant in a series of 3 nutrient limited laboratory reactor experiments, and a pure culture of Thiothrix unzii (ATCC type strain 49747) in a parallel experiment, we found that both limestone and dolostone substratum consistently had higher biomass accumulation than silicate minerals in the same reactor. At the Class level, the carbonate substratum (Calcite, Limestone, and Dolostone) had ~84% - 88.7% of phylotypes in common. Aside from Basalt (Simpson's Index, D of 0.53), the carbonate substratum produced the least diverse phylotype distributions. Feldspar and quartz were colonized by the most diverse communities with Simpson's Index values of 0.16 and 0.31. Evaluation of metabolic guild distribution shows that potential neutrophilic sulfur-oxidizers have an affinity for acid neutralizing carbonate substrata over silicate substrata. These potential sulfur-oxidizing guilds compose ~28%-38% of the total microbial community. For feldspar and chert substratum, potential sulfur-oxidizing metabolic guilds composed merely ~5% of the total microbial community. The quartz substratum, in contrast, was uniquely populated by potential acidophilic sulfur-oxidizers Acidithiobacillus and Acidithiomicrobium; composing ~19% of the total community. A quartz substratum may offer these acidophiles a competitive advantage over other microbial communities that do not tolerate an acidic habitat, while optimizing the local microenvironment to better facilitate their metabolic pathway. The basalt substratum community was ~67% Thiothrix spp., a sulfur-oxidizing genus commonly associated with Deep-sea hydrothermal vents. This dominance of Thiothrix spp. on basalt may be due to an advantageous ability to extract, and take advantage of, mineral bound nutrients (P, Fe) in basalt. These results provide substantial evidence to support the hypothesis that mineralogy influences microbial distribution, composition, niche differentiation, and accumulation in a nutrient limited system. Specific microbial populations which have evolved to take advantage of specific mineral substrata and exert highly localized control of biogeochemical conditions. Mineralogy, therefore, plays an active part in the development of subsurface microbial ecology and diversity by exerting selective pressures on the subsurface microbial environment.

  9. Uptake of formaldehyde by sulfuric acid solutions - Impact on stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Pfaff, Jeanne; Jayaweera, Indira; Prather, Michael J.

    1993-01-01

    The study investigates the uptake of CH2O by low temperature sulfuric acid solutions representative of global stratospheric particulate. It is argued that if similar uptake occurs under stratospheric pressures of CH2O, i.e., 1000 times lower than used in the present study, then the removal of CH2O from the gas phase can take away a significant source of odd hydrogen in the mid- and high-latitude lower stratosphere. It is shown that with the inclusion of this reaction, concentrations of OH and H2O are reduced by as much as 4 percent under background levels of aerosols and more than 15 percent under elevated (volcanic) conditions. The accumulation of CH2O in stratospheric aerosols over a season, reaching about 1 M solutions, will alter the composition and may even change the reactivity of these sulfuric acid-water mixtures.

  10. Synergistic inhibition of corrosion of steel in sulfuric acid solutions

    SciTech Connect

    Gordeeva, I.I.; Efimov, I.V.; Legin, G.Y.

    1985-07-01

    The authors have studied synergism in compositions of sodium chloride with simple aliphatic compounds containing the neutral phosphate AF-1, the neutral phosphonate AF-10, and the trialkylphosphine oxide AF-13. In contrast with the amines, all the substances have extremely low basicity and are almost incapable of forming cations in an acidic medium. The substances exhibit marked synergism with chloride ions. For comparison, the authors caused the inhibition of steel Stl with carbonyl compounds similar in structure to the three substances, namely diethyl carbonate, butyl acetate, and 2-octanone. The carbonyl compounds are weaker inhibitors, but in compositions with sodium chloride, their qualitative effects are similar to those of phosphoryl compounds.

  11. Kinetic and Modeling Investigation on Dilute Sulfuric Acid and Hot Water Fractionation of Selected Biomass Plan

    SciTech Connect

    Lee, Y. Y.; Chen, R. B.; Wu, Z.; Hayes, J.

    2004-09-01

    Subcontractor developed a processing model to evaluate and optimize an NREL-developed biomass pretreatment technology. The technology, taking advantage of the biphasic nature of hemicellulose in pretreatment, is a two-stage, reverse-flow, shrinking-bed system. The contract simulation found that this system could increase sugar yield by about 5%, with bed shrinkage of 27% and sugar yield of 95% at optimum conditions.

  12. Regenerated cellulose films from NaOH\\/urea aqueous solution by coagulating with sulfuric acid

    Microsoft Academic Search

    Jinping Zhou; Lina Zhang; Hong Shu; Fangeng Chen

    2002-01-01

    A series of novel regenerated cellulose (RC) films was prepared from cotton linters in 6 wt% NaOH\\/4 wt% urea aqueous solution by coagulating with 1–20 wt% sulfuric acid (H2SO4) aqueous for 1–20 min. Dependences of structure, morphology, light transmittance, mechanical properties, and water permeability of the films on the H2SO4 concentration and the coagulation time were investigated by using IR, UV–Vis, x-ray diffraction, scanning

  13. Extraction of aluminum and iron from boiler slag by sulfuric acid

    Microsoft Academic Search

    Jinping Li; Haobo Hou; Jinhua Gan; Shujing Zhu; Yongjie Xie

    2007-01-01

    This paper presents a new method of recycling aluminum and iron in boiler slag derived from plants that use coal as fuel.\\u000a The new method integrates efficient extraction and reuse of the leached pellets together. An elemental analysis of aqueous\\u000a solutions leached by sulfuric acid was determined by EDTA-Na2-ZnCl2 titration method. The components and microstructures of the samples were examined

  14. Design bases: Bauxite-sulfuric acid feed facilities 100-K Area

    SciTech Connect

    Etheridge, E.L.

    1993-06-10

    This document defines the objective, bases, and functional requirements governing the preparation of detail design of the bauxite-sulfuric acid feed facilities to be installed in the 183-KE and KW buildings. These facilities will produce the chemical coagulant used in the treatment of Columbia River water in the water plants; they will replace existing liquid alum feed systems. The treated water will be used as reactor coolant.

  15. Life of AG4s glass-fiber-reinforced plastic in bending in sulfuric acid

    Microsoft Academic Search

    A. A. Shevchenko; A. S. Krasovitskii; V. P. Starikov

    1978-01-01

    We have investigated the life of AG-4s unidirectional glass-fiber-rein forced plastic in bending and at increased temperatures in sulfuric acid of different concentrations. The tests were made using a four-point loading method with a ratio of the distance between the supports to the height of the sample of more than 20. The zone of pure bending was 1\\/3 of the

  16. Quantitative trait loci controlling sulfur containing amino acids, methionine and cysteine, in soybean seeds

    Microsoft Academic Search

    D. R. Panthee; V. R. Pantalone; C. E. Sams; A. M. Saxton; D. R. West; J. H. Orf; A. S. Killam

    2006-01-01

    Soybean [Glycine max (L.) Merr.] is the single largest source of protein in animal feed. However, a major limitation of soy proteins is their\\u000a deficiency in sulfur-containing amino acids, methionine (Met) and cysteine (Cys). The objective of this study was to identify\\u000a quantitative trait loci (QTL) associated with Met and Cys concentration in soybean seed. To achieve this objective, 101

  17. A computationally efficient aerosol nucleation/condensation method: Pseudo-steady state gas phase sulfuric acid

    NASA Astrophysics Data System (ADS)

    Adams, P. J.; Pierce, J. R.

    2007-12-01

    Aerosol nucleation and condensation are two processes that compete for gas phase sulfuric acid when it is formed in the atmosphere. Without approximations, accurate numerical integration of aerosol microphysics requires time steps on the order of seconds or less when nucleation is occurring, significantly shorter than the time steps required by other processes governing aerosol microphysics. This computational burden makes the explicit numerical simulation burdensome in 3-dimensional atmospheric models. We have developed an efficient method for simulating nucleation/condensation by assuming that gas phase sulfuric acid is at a pseudo- steady state (PSS) concentration determined by chemical generation and its loss by nucleation and condensation. The time step for nucleation/condensation is then governed by 1) the change in the condensation sink, 2) the change in the generation rate of sulfuric acid, 3) the coagulation timescale, or 4) a master time step in the model. The PSS assumption fails only when the time for sulfuric acid to reach its PSS state concentration is not significantly shorter than the four timescales above. This may occur when the following conditions are met 1) the condensation sink is less than 10-3-10-4 s-1, 2) nucleation is not occurring, and 3) the gas phase production rate is changing. These conditions are not frequently met for a long period of time in the atmosphere. The PSS assumption allows for time step increases of two to three orders of magnitude during nucleation events in typical atmospheric conditions and has been shown to reduce the nucleation/condensation computational time by a factor of 10-100.

  18. A global three-dimensional model of the stratospheric sulfuric acid layer

    NASA Technical Reports Server (NTRS)

    Golombek, Amram; Prinn, Ronald G.

    1993-01-01

    A 3D model which encompasses SO2 production from OCS, followed by its oxidation to gaseous H2SO4, the condensation-evaporation equilibrium of gaseous and particulate H2SO4, and finally particle condensation and rainout, is presently used to study processes maintaining the nonvolcanically-perturbed stratosphere's sulfuric acid layer. A comparison of the results thus obtained with remotely sensed stratospheric aerosol extinction data shows the model to simulate the general behavior of stratospheric aerosol extinction.

  19. Effects of sulfur containing amino acids on iron and nitric oxide stimulated catecholamine oxidation.

    PubMed

    Biasetti, M; Dawson, R

    2002-06-01

    Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined for their actions to stimulate quinone formation. Taurine attenuated iron-stimulated quinone formation from catecholamines suggesting that it may function as an endogenous antioxidant. Several other sulfur-containing amino acids (homocysteic acid, cysteine sulfinic acid and SAM) were found to inhibit catecholamine oxidation. Among other amino acids tested, homocysteine had biphasic effects; attenuating L-dopa oxidation catalyzed by ferric chloride and potentiating norepinephrine's oxidation catalyzed by both ferric chloride and sodium nitroprusside (SNP). Homotaurine and homocysteine (1 or 10 mM) greatly stimulated SNP-induced norepinephrine oxidation. Homotaurine potentiated quinone formation in the presence of ferric iron and this effect was attenuated by desferroxamine. In order to exclude a possible NO/iron interaction in SNP's oxidizing action, SIN-1 chloride, a specific NO-donor, was tested as an oxidizing agent. The failure of desferroxamine or taurine to attenuate SIN-1 oxidation of norepinephrine suggests that peroxynitrite-mediated oxidation was likely the dominant mechanism. Our results show that endogenous sulfur containing amino acids, like taurine, could serve a protective role to reduce cellular damage associated with both NO and metal-stimulated catecholamine oxidation. PMID:12107762

  20. Refined understanding of sulfur amino acid nutrition in hybrid striped bass, Morone chrysops (male symbol) x M. saxatilis (female symbol) 

    E-print Network

    Kelly, Mark Christopher

    2005-08-29

    Previous studies have indicated the level of total sulfur amino acids (TSAA) (methionine + cystine) is most limiting in practical diet formulations for hybrid striped bass (HSB), especially if animal feedstuffs are replaced with plant feedstuffs...

  1. Dilute nitric or nitrous acid solution containing halide ions as effective media for pure gold dissolution.

    PubMed

    Hojo, Masashi; Yamamoto, Masahiko; Okamura, Kei

    2015-08-14

    The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10-2.0 mol L(-1)) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30-60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol L(-1) HNO3 solution containing 1.0-5.0 mol L(-1) NaBr and the dissolution rate constant, log(k/s(-1)), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The addition of organic solvents, such as acetonitrile and acetic acid, causes acceleration of gold dissolution in LiBr and NaBr solutions. With increasing MeCN contents, for instance, the log(k/s(-1)) value of 0.10 mol L(-1) HNO3 solution containing 2.0 mol L(-1) NaBr increases linearly from -5.30 to -4.61 at 30% (v/v) MeCN. The bromide salts affect the gold dissolution rate constant in the order of KBr < NaBr < LiBr < CaBr2. With increasing NaI concentration (0.20-3.0 mol L(-1)), some acceleration in log(k/s(-1)) of 0.50 or 1.0 mol L(-1) HNO3 solution has been observed; however, the slope of acceleration as the function of NaI concentration is much smaller than that of NaCl or NaBr. The gold dissolution ability has been examined also for nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s(-1)) values of the mixed solutions of NaNO2 (0.10-2.0 mol L(-1)) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in "modified" aqueous solutions and not of the changes in the activity coefficients of ions. PMID:26165394

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

    PubMed Central

    Schobesberger, Siegfried; Junninen, Heikki; 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, Joćo; 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 molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions. PMID:24101502

  3. The charging of neutral dimethylamine and dimethylamine-sulfuric acid clusters using protonated acetone

    NASA Astrophysics Data System (ADS)

    Ruusuvuori, K.; Hietala, P.; Kupiainen-Määttä, O.; Jokinen, T.; Junninen, H.; Sipilä, M.; Kurtén, T.; Vehkamäki, H.

    2015-06-01

    Sulfuric acid is generally considered one of the most important substances taking part in atmospheric particle formation. However, in typical atmospheric conditions in the lower troposphere, sulfuric acid and water alone are unable to form particles. It has been suggested that strong bases may stabilize sulfuric acid clusters so that particle formation may occur. More to the point, amines - strong organic bases - have become the subject of interest as possible cause for such stabilization. To probe whether amines play a role in atmospheric nucleation, we need to be able to measure accurately the gas-phase amine vapour concentration. Such measurements often include charging the neutral molecules and molecular clusters in the sample. Since amines are bases, the charging process should introduce a positive charge. This can be achieved by, for example, using chemical ionization with a positively charged reagent with a suitable proton affinity. In our study, we have used quantum chemical methods combined with a cluster dynamics code to study the use of acetone as a reagent ion in chemical ionization and compared the results with measurements performed with a chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF). The computational results indicate that protonated acetone is an effective reagent in chemical ionization. However, in the experiments the reagent ions were not depleted at the predicted dimethylamine concentrations, indicating that either the modelling scheme or the experimental results - or both - contain unidentified sources of error.

  4. Stability of mechanical properties of vanadium catalysts for sulfuric acid manufacture in a humid atmosphere

    SciTech Connect

    Manaeva, L.N.; Malikman, V.I.; Dobkina, E.I.; Mukhlenov, I.P.

    1982-01-10

    Experience of the industrial use of catalysts in sulfuric acid manufacture shows that as the result of saturation with moisture the catalyst grains may lose strength and disintegrate during use. However, this question has not been examined experimentally and the mechanism of the effect has not been studied. Fresh catalyst may come into contact with atmospheric moisture during storage, and used catalyst as the result of uncontrolled leakages during stoppages and recharging of the catalytic converters. In the course of normal operation water vapor enters the catalytic converters together with sulfuric acid mist with the gas stream if the latter has not been adequately dried. The purpose of the present work was to study the mechanical stability, in a humid atmosphere, of industrial sulfuric acid catalysts: granulated SVD (5 mm in diameter) and SVS rings (8 x 8 x 2.5 mm). The catalysts were studied both in the fresh state and after use in a laboratory catalytic apparatus of the flow type.

  5. Assessing the molecular structure basis for biomass recalcitrance during dilute acid and hydrothermal pretreatments

    PubMed Central

    2013-01-01

    The production of cellulosic ethanol from biomass is considered a promising alternative to reliance on diminishing supplies of fossil fuels, providing a sustainable option for fuels production in an environmentally compatible manner. The conversion of lignocellulosic biomass to biofuels through a biological route usually suffers from the intrinsic recalcitrance of biomass owing to the complicated structure of plant cell walls. Currently, a pretreatment step that can effectively reduce biomass recalcitrance is generally required to make the polysaccharide fractions locked in the intricacy of plant cell walls to become more accessible and amenable to enzymatic hydrolysis. Dilute acid and hydrothermal pretreatments are attractive and among the most promising pretreatment technologies that enhance sugar release performance. This review highlights our recent understanding on molecular structure basis for recalcitrance, with emphasis on structural transformation of major biomass biopolymers (i.e., cellulose, hemicellulose, and lignin) related to the reduction of recalcitrance during dilute acid and hydrothermal pretreatments. The effects of these two pretreatments on biomass porosity as well as its contribution on reduced recalcitrance are also discussed. PMID:23356640

  6. Advances in Acid Concentration Membrane Technology for the Sulfur-Iodine Thermochemical Cycle

    SciTech Connect

    Frederick F. Stewart; Christopher J. Orme

    2006-11-01

    One of the most promising cycles for the thermochemical generation of hydrogen is the Sulfur-Iodine (S-I) process, where aqueous HI is thermochemically decomposed into H2 and I2 at approximately 350 degrees Celsius. Regeneration of HI is accomplished by the Bunsen reaction (reaction of SO2, water, and iodine to generate H2SO4 and HI). Furthermore, SO2 is regenerated from the decomposition of H2SO4 at 850 degrees Celsius yielding the SO2 as well as O2. Thus, the cycle actually consists of two concurrent oxidation-reduction loops. As HI is regenerated, co-produced H2SO4 must be separated so that each may be decomposed. Current flowsheets employ a large amount (~83 mol% of the entire mixture) of elemental I2 to cause the HI and the H2SO4 to separate into two phases. To aid in the isolation of HI, which is directly decomposed into hydrogen, water and iodine must be removed. Separation of iodine is facilitated by removal of water. Sulfuric acid concentration is also required to facilitate feed recycling to the sulfuric acid decomposer. Decomposition of the sulfuric acid is an equilibrium limited process that leaves a substantial portion of the acid requiring recycle. Distillation of water from sulfuric acid involves significant corrosion issues at the liquid-vapor interface. Thus, it is desirable to concentrate the acid without boiling. Recent efforts at the INL have concentrated on applying pervaporation through Nafion-117, Nafion-112, and sulfonated poly(etheretherketone) (S-PEEK) membranes for the removal of water from HI/water and HI/Iodine/water feedstreams. In pervaporation, a feed is circulated at low pressure across the upstream side of the membrane, while a vacuum is applied downstream. Selected permeants sorb into the membrane, transport through it, and are vaporized from the backside. Thus, a concentration gradient is established, which provides the driving force for transport. In this work, membrane separations have been performed at temperatures as high as 134 degrees Celsius. Transmembrane fluxes of water are commercially competitive (~5000 g/m2h) and separation factors have been measured as high as 8000, depending on the membrane and the water content. For the Nafion-117 experiments, the common trade off in membrane performance is observed in that as flux is increased, separation factor decreases. Nafion-112, a thinner membrane, exhibited much higher fluxes than the Nafion-117; however without the expected loss in separation factor indicating that the permeability of iodine and HI through Nafion materials is low. Preliminary data for the sulfuric acid concentration suggests performance similar to the HI experiments. All membranes studied for the HI, HI/iodine and sulfuric acid feeds exhibited no degradation in membrane performance during use.

  7. From gas-phase oxidation of SO2 by SO4- to the formation of sulfuric acid

    NASA Astrophysics Data System (ADS)

    Tsona, Narcisse; Bork, Nicolai; Vehkamäki, Hanna

    2013-05-01

    One of the difficulties to predict atmospheric nucleation is related to inaccurate measure of the total sulfuric acid concentration. We present a density functional theory investigation of the SO2 gas phase oxidation by SO4-. In the immediate product, SO2.SO4- cluster, SO2 is subsequently oxidized and SO3SO3- is formed at 1.7 × 10-7 s-1 reaction rate. SO3SO3- interacts with O2 molecule to form SO3 and SO5-, which are important species in the gas phase chemistry of sulfur and in the formation mechanism of sulfuric acid.

  8. Microbial dissimilatory sulfur cycle in acid mine water.

    PubMed

    Tuttle, J H; Dugan, P R; Macmillan, C B; Randles, C I

    1969-02-01

    Ferric, sulfate, and hydrogen ions are produced from pyritic minerals associated with coal as a result of autotrophic bacterial metabolism. Water carrying these ions accumulated behind a porous dam composed of wood dust originating at a log-cutting mill. As water seeped through the porous dam, it was enriched in organic nutrients which then supported growth and metabolism of heterotrophic bacteria in the water downstream from the dam. The heterotrophic microflora within and below the sawdust dam included dissimilatory sulfate-reducing anaerobic bacteria which reduce sulfate to sulfide. The sulfide produced caused the chemical reduction of ferric to ferrous ion, and black FeS precipitate was deposited on the pond bottom. A net increase in the pH of the lower pond water was observed when compared to the upper pond water. Microbial activity in the wood dust was demonstrated, and a sequence of cellulose degradation processes was inferred on the basis of sugar accumulation in mixed cultures in the laboratory, ultimately yielding fermentation products which serve as nutrients for sulfate-reducing bacteria. Some of the microorganisms were isolated and characterized. The biochemical and growth characteristics of pure culture isolates were generally consistent with observed reactions in the acidic environment, with the exception of sulfate-reducing bacteria. Mixed cultures which contained sulfate-reducing bacteria reduced sulfate at pH 3.0 in the laboratory with sawdust as the only nutrient. Pure cultures of sulfate-reducing bacteria isolated from the mixed cultures did not reduce sulfate below pH 5.5. PMID:5773013

  9. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2011-10-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying nitrogen, respectively argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings lead to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume, that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  10. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2012-05-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying either nitrogen or argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed at a supersaturation of 1%, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings led to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  11. On the mechanism of the hypolipidemic effect of sulfur-substituted hexadecanedioic acid (3-thiadicarboxylic acid) in normolipidemic rats.

    PubMed

    Skorve, J; al-Shurbaji, A; Asiedu, D; Björkhem, I; Berglund, L; Berge, R K

    1993-07-01

    The mechanism behind the hypolipidemic effect of the sulfur-substituted non-beta-oxidizable fatty acid analogue 1,10 bis(carboxymethylthio)decane, also known as 3-thiadicarboxylic acid, was studied in normolipidemic rats. Treatment with 3-thiadicarboxylic acid markedly decreased plasma levels of free fatty acids, triglycerides, and cholesterol. This was accompanied by a corresponding reduction in very low density lipoprotein (VLDL)-triglyceride and low density lipoprotein (LDL)-cholesterol levels (by 46% and 42%, respectively), whereas the decrease in high density lipoprotein (HDL)-cholesterol levels was less pronounced (16%). However, the composition of the various plasma lipoprotein fractions was essentially unchanged. Fatty acid oxidation in both mitochondria and peroxisomes was stimulated in parallel; the activities of ATP:citrate lyase and fatty acid synthase, two key enzymes in fatty acid synthesis, were inhibited. Hepatic triglyceride biosynthesis was retarded, as indicated by a decrease in the liver triglyceride content along with a 30% reduction of hepatic VLDL-triglyceride secretion. This was accompanied by a 50% inhibition of phosphatidate phosphohydrolase. The activities of plasma lipoprotein lipase as well as hepatic lipase were somewhat higher (18%) in treated animals, suggesting a slight increase in the clearance potential of triglyceride-rich lipoproteins. The cholesterol-lowering effect was accompanied by a considerable reduction (75%) in HMG-CoA reductase activity and a less pronounced inhibition of cholesterol 7 alpha-hydroxylase (52%), and acyl-CoA:cholesterol acyltransferase (25%) activities. The present data suggest that the hypotriglyceridemic and hypocholesterolemic properties of sulfur-substituted fatty acid analogues are primarily due to effects on triglyceride and cholesterol synthesis. PMID:8371065

  12. Effects of simulated sulfuric acid rain on yield, growth, and foliar injury of several crops

    SciTech Connect

    Lee, J.J.; Neely, G.E.; Perrigan, S.C.; Grothaus, L.C.

    1980-10-01

    This study was designed to reveal patterns of response of major United States crops to sulfuric acid rain. Potted plants were grown in field chambers and exposed to simulated sulfuric acid rain (pH 3.0, 3.5 or 4.0) or to a control rain (pH 5.6). At harvest, the weights of the marketable portion, total aboveground portion and roots were determined for 28 crops. Of these, marketable yield production was inhibited for 5 crops (radish, beet, carrot, mustard greens, broccoli), stimulated for 6 crops (tomato, green pepper, strawberry, alfalfa, orchardgrass, timothy), and ambiguously affected for 1 crop (potato). In addition, stem and leaf production of sweet corn was stimulated. Visible injury of tomatoes might have decreased their marketability. No statistically significant effects on yield were observed for the other 15 crops. The results suggest that the likelihood of yield being affected by acid rain depends on the part of the plant utilized, as well as on species. Effects on the aboveground portions of crops and on roots are also presented. Plants were regularly examined for foliar injury associated with acid rain. Of the 35 cultivars examined, the foliage of 31 was injured at pH 3.0, 28 at pH 3.5, and 5 at pH 4.0. Foliar injury was not generally related to effects on yield. However, foilar injury of swiss chard, mustard greens and spinach was severe enough to adversely affect marketability.

  13. Porewater geochemistry of inland Acid sulfate soils with sulfuric horizons following postdrought reflooding with freshwater.

    PubMed

    Creeper, Nathan L; Shand, Paul; Hicks, Warren; Fitzpatrick, Rob W

    2015-05-01

    Following the break of a severe drought in the Murray-Darling Basin, rising water levels restored subaqueous conditions to dried inland acid sulfate soils with sulfuric horizons (pH <3.5). Equilibrium dialysis membrane samplers were used to investigate in situ changes to soil acidity and abundance of metals and metalloids following the first 24 mo of restored subaqueous conditions. The rewetted sulfuric horizons remained severely acidified (pH ?4) or had retained acidity with jarosite visibly present after 5 mo of continuous subaqueous conditions. A further 19 mo of subaqueous conditions resulted in only small additional increases in pH (?0.5-1 pH units), with the largest increases occurring within the uppermost 10 cm of the soil profile. Substantial decreases in concentrations of some metal(loid)s were observed with time most likely owing to lower solubility and sorption as a consequence of the increase in pH. In deeper parts of the profiles, porewater remained strongly buffered at low pH values (pH <4.5) and experienced little progression toward anoxic circumneutral pH conditions over the 24 mo of subaqueous conditions. It is proposed that low pH conditions inhibited the activity of SO-reducing bacteria and, in turn, the in situ generation of alkalinity through pyrite production. The limited supply of alkalinity in freshwater systems and the initial highly buffered low pH conditions were also thought to be slowing recovery. The timescales involved for a sulfuric horizon rewetted by a freshwater body to recover from acidic conditions could therefore be in the order of several years. PMID:26024279

  14. Pristanic acid and phytanic acid in plasma from patients with peroxisomal disorders: stable isotope dilution analysis with electron capture negative ion mass fragmentography

    Microsoft Academic Search

    H. J. ten Brink; F. Stellaard; C. M. M. van den Hewel; R. M. Kok; C. Jakobs

    A sensitive and selective stable isotope dilution method was developed for the accurate quantitation of pris- tanic acid and phytanic acid using electron capture nega- tive ion mass fragmentography on pentafluorobenzyl derivatives. This technique allows detection of 1 pg of each compound and was applied to plasma from healthy controls and patients suffering from various peroxisomal disorders. The age-dependency of

  15. The effect of overliming on the toxicity of dilute acid pretreated lignocellulosics: the role of inorganics, uronic acids and ether-soluble organics

    Microsoft Academic Search

    Thilini D Ranatunga; Judith Jervis; Richard F Helm; James D McMillan; Robert J Wooley

    2000-01-01

    Although the treatment of dilute acid pretreated lignocellulosics with calcium hydroxide or carbonate (overliming) is known to improve the fermentability of carbohydrate-rich hydrolyzate streams, a firm understanding of the chemistry behind the process is lacking. Quantitative evaluation of inorganics, uronic acids, and non-polar organics indicates that only a portion of the improvement can be ascribed to these materials. Upon overliming

  16. Radiolytic Modification of Sulfur Containing Acidic Amino Residues in Model Peptides: Fundamental Studies for Protein Footprinting

    SciTech Connect

    Xu,G.; Chance, M.

    2005-01-01

    Protein footprinting based on hydroxyl radical-mediated modification and quantitative mass spectroscopic analysis is a proven technique for examining protein structure, protein-ligand interactions, and structural allostery upon protein complex formation. The reactive and solvent-accessible amino acid side chains function as structural probes; however, correct structural analysis depends on the identification and quantification of all the relevant oxidative modifications within the protein sequence. Sulfur-containing amino acids are oxidized readily and the mechanisms of oxidation are particularly complex, although they have been extensively investigated by EPR and other spectroscopic methods. Here we have undertaken a detailed mass spectrometry study (using electrospray ionization mass spectrometry and tandem mass spectrometry) of model peptides containing cysteine (Cys-SH), cystine (disulfide bonded Cys), and methionine after oxidation using {gamma}-rays or synchrotron X-rays and have compared these results to those expected from oxidation mechanisms proposed in the literature. Radiolysis of cysteine leads to cysteine sulfonic acid (+48 Da mass shift) and cystine as the major products; other minor products including cysteine sulfinic acid (+32 Da mass shift) and serine (-16 Da mass shift) are observed. Radiolysis of cystine results in the oxidative opening of the disulfide bond and generation of cysteine sulfonic acid and sulfinic acid; however, the rate of oxidation is significantly less than that for cysteine. Radiolysis of methionine gives rise primarily to methionine sulfoxide (+16 Da mass shift); this can be further oxidized to methionine sulfone (+32 Da mass shift) or another product with a -32 Da mass shift likely due to aldehyde formation at the {gamma}-carbon. Due to the high reactivity of sulfur-containing amino acids, the extent of oxidation is easily influenced by secondary oxidation events or the presence of redox reagents used in standard proteolytic digestions; when these are accounted for, a reactivity order of cysteine > methionine {approx} tryptophan > cystine is observed.

  17. Effect of physical pretreatment on dilute acid hydrolysis of water hyacinth (Eichhornia crassipes).

    PubMed

    Harun, M Y; Dayang Radiah, A B; Zainal Abidin, Z; Yunus, R

    2011-04-01

    Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H(2)SO(4), 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process. PMID:21333529

  18. Kinetic modeling of hardwood prehydrolysis. Part II. Xylan removal by dilute hydrochloric acid prehydrolysis

    SciTech Connect

    Connor, A.H.; Libkie, K.; Springer, E.L.

    1986-06-01

    A study was made of the kinetics of xylan hemicellulose removal with 0.10 M HCl at 120 degrees C from quaking aspen (Populus tremuloides), paper birch (Betula papyrifera), American elm (Ulmus americana), red maple (Acer rubrum), and southern red oak (Quercus falcata). The mathematical model developed in Part I to describe the kinetics of xylan removal by water prehydrolysis of these species could be used to model xylan removal with dilute hydrochloric acid. Xylan removal could thus be modelled as the sum of two parallel first-order reactions - one fast and one slow. However, unlike the case with water prehydrolysis where the rate constants for the fast and slow reaction processes could be correlated with each other, they could not be correlated for HCl prehydrolysis. Instead, these constant values determined for each species clustered about average values for all the species as a whole. A single set of parameters determined from a nonlinear least squares fit of the experimental prehydrolysis data for all the species as a whole to the model could be used to describe the course of xylan removal from all the species. The fact that one set of parameters could be used suggests that the same reactions are taking place on prehydrolysis and the chemical structure and physical morphology of the xylan hemicellulose were essentially the same in the species studied and probably in all temperate hardwood species. The model thus provides a good approximation of xylan removal from any temperate hardwood with dilute hydrochloric acid at the reaction conditions studied. 20 references.

  19. Impacts of Deacetylation Prior to Dilute Acid Pretreatment on the Bioethanol Process

    SciTech Connect

    Chen, X.; Shekiro, J.; Franden, M. A.; Wang, W.; Johnson, D. K.; Zhang, M.; Kuhn, E.; Tucker, M. P.

    2011-12-01

    Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: (1) cleavage of the xylosidic bonds, and (2) cleavage of covalently bonded acetyl ester groups. Results: In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustness of the deacetylation-pretreatment-saccharification-fermentation process. Conclusions: Deacetylation shows significant improvement on glucose and xylose yields during pretreatment and enzymatic hydrolysis, but it also reduces hydrolyzate toxicity during fermentation, thereby improving ethanol yields and titer. The magnitude of effect is dependent on the selected corn stover variety, with several varieties achieving improvements of greater than 10% xylose yield in pretreatment, 20% glucose yield in low solids enzymatic hydrolysis and 7% overall ethanol yield.

  20. A novel method for the quantification of quinic acid in food using stable isotope dilution analysis.

    PubMed

    Erk, Thomas; Bergmann, Hannah; Richling, Elke

    2009-01-01

    Organic acids play an important role in the flavor and taste of plant-derived foods. Quinic acid (QA) is one of the major acids. In the past, several methods like HPLC/UV, GC, and capillary electrophoresis were used for identification and quantification of QA. For the first time, a novel, sensitive, and selective method for the quantification of QA in food using stable isotope dilution analysis with HPLC/MS/MS has been established. Uniformly labeled 13C-QA was used as a standard to reduce sample preparations and to overcome matrix and ionization effects. The method was used to determine the QA content of red wines, instant coffees, and cloudy apple juices. QA contents of instant coffees were 64.4 and 63.6 g/kg powder. The concentrations in red wines were 24.0 and 25.1 mg/L, and 1493.3 and 1705.2 mg/L in cloudy apple juices. PMID:19610361

  1. Non-spectral interferences due to the presence of sulfuric acid in inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Garcķa-Poyo, M. Carmen; Grindlay, Guillermo; Gras, Luis; de Loos-Vollebregt, Margaretha T. C.; Mora, Juan

    2015-03-01

    Results of a systematic study concerning non-spectral interferences from sulfuric acid containing matrices on a large number of elements in inductively coupled plasma-mass spectrometry (ICP-MS) are presented in this work. The signals obtained with sulfuric acid solutions of different concentrations (up to 5% w w- 1) have been compared with the corresponding signals for a 1% w w- 1- nitric acid solution at different experimental conditions (i.e., sample uptake rates, nebulizer gas flows and r.f. powers). The signals observed for 128Te+, 78Se+ and 75As+ were significantly higher when using sulfuric acid matrices (up to 2.2-fold for 128Te+ and 78Se+ and 1.8-fold for 75As+ in the presence of 5 w w-1 sulfuric acid) for the whole range of experimental conditions tested. This is in agreement with previously reported observations. The signal for 31P+ is also higher (1.1-fold) in the presence of sulfuric acid. The signal enhancements for 128Te+, 78Se+, 75As+ and 31P+ are explained in relation to an increase in the analyte ion population as a result of charge transfer reactions involving S+ species in the plasma. Theoretical data suggest that Os, Sb, Pt, Ir, Zn and Hg could also be involved in sulfur-based charge transfer reactions, but no experimental evidence has been found. The presence of sulfuric acid gives rise to lower ion signals (about 10-20% lower) for the other nuclides tested, thus indicating the negative matrix effect caused by changes in the amount of analyte loading of the plasma. The elemental composition of a certified low-density polyethylene sample (ERM-EC681K) was determined by ICP-MS after two different sample digestion procedures, one of them including sulfuric acid. Element concentrations were in agreement with the certified values, irrespective of the acids used for the digestion. These results demonstrate that the use of matrix-matched standards allows the accurate determination of the tested elements in a sulfuric acid matrix.

  2. Mercury Adsorption on Sulfuric Acid-Impregnated Carbonaceous Surface: Theoretical Study

    NASA Astrophysics Data System (ADS)

    He, Ping; Wu, Jiang; Jiang, Xiumin; Pan, Weiguo; Ren, Jianxing

    2014-01-01

    Density functional theory calculations are performed to provide a molecular-level understanding of the mechanism of mercury adsorption on sulfuric acid-impregnated carbonaceous surface. The carbonaceous surface is modeled by a nine-fused benzene ring in which its edge carbon atoms on the upper side are unsaturated to simulate the active sites for reaction. SO4 clusters with and without charge are examined to act as the representative species to model the sulfuric acid absorbed on the carbonaceous surface. All of the possible approaches of SO4 clusters with and without charge on the carbonaceous surface are conduced to study their effects on mercury adsorption. The results suggest that sulfuric acid effect on the mercury adsorption capacity of the carbonaceous surface is very complicated, and it depends on a combination of concentration and charge of SO4 cluster. SO4 cluster presents a positive effect on mercury adsorption on the carbonaceous surface, but higher concentration of SO4 cluster decreases the adsorption capacity of the carbonaceous surface for mercury removal because there is considerable competition for active sites between Hg and SO4 cluster. Since all of the possible approaches of mercury on the carbonaceous surface with SO42- cluster, excluding one that mercury is adsorbed at bridge active site, can lead to the decrease in the adsorption energies of mercury on the carbonaceous surface, SO42- cluster presents a negative effect on the capacity of the carbonaceous surface for mercury adsorption regardless of the concentration of SO42- cluster. The results also indicate that SO2 cluster and surface oxygen complex can be formed from SO4 cluster with or without charge if mercury is adsorbed at bridge active site, which facilitates the mercury removal for the carbonaceous surface.

  3. Heterogeneous reactions in sulfuric acid aerosols: A framework for model calculations

    SciTech Connect

    Hanson, D.R.; Ravishankara, A.R.; Solomon, S. [National Oceanic and Atmospheric Administration, Boulder, CO (United States)] [National Oceanic and Atmospheric Administration, Boulder, CO (United States); [Univ. of Colorado, Boulder, CO (United States)

    1994-02-20

    A framework for applying rates of heterogeneous chemical reactions measured in the laboratory to small sulfuric acid aerosols found in the stratosphere is presented. The procedure for calculating the applicable reactive uptake coefficients using laboratory-measured parameters is developed, the necessary laboratory-measured quantities are discussed, and a set of equations for use in models are presented. This approach is demonstrated to be essential for obtaining uptake coefficients for the HOCl+HCl and ClONO{sub 2}+HCl reactions applicable to the stratosphere. In these cases the laboratory-measured uptake coefficients have to be substantially corrected for the small size of the atmospheric aerosol droplets. The measured uptake coefficients for N{sub 2}O{sub 5}+H{sub 2}O and ClONO{sub 2}+H{sub 2}O as well as those for other heterogeneous reactions are discussed in the context of this model. Finally, the derived uptake coefficients were incorporated in two-dimensional dynamical and photochemical model. Thus for the first time the HCl reactions in sulfuric acid have been included. Substantial direct chlorine activation and consequent ozone destruction is shown to occur due to heterogeneous reactions involving HCl for volcanically perturbed aerosol conditions at high latitudes. Smaller but significant chlorine activation also is predicted for background sulfuric acid aerosol in these regions. The coupling between homogeneous and heterogeneous chemistry is shown to lead to important changes in the concentrations of various reactive species. The basic physical and chemical quantities needed to better constrain the model input parameters are identified. 39 refs., 10 figs., 4 tabs.

  4. Preparation and characterization of silver loaded montmorillonite modified with sulfur amino acid

    NASA Astrophysics Data System (ADS)

    Li, Tian; Lin, Oulian; Lu, Zhiyuan; He, Liuimei; Wang, Xiaosheng

    2014-06-01

    The Na+ montmorillonite (MMT) was modified with sulfur containing amino acid (L-cystine, L-cysteine or L-methionine) and characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). The results showed the modification was smooth and the surface condition of MMT was changed with sulfur containing groups. Then silver was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation, the spectra of X-ray photoelectron spectroscopy (XPS), EDS and FT-IR confirmed the successful loading of massive silver and the strong interaction between sulfur and silver, the silver loaded L-cystine modified MMT (Ag@AA-MMT-3) with a silver content of 10.93 wt% was the highest of all. Further more, the Ag@AA-MMT-3 was under the irradiation of a UV lamp to turn silver ions to silver nano particles (Ag NPs). The XPS, specific surface area (SSA), transmission electron microscopy (TEM), XRD patterns and UV-vis spectra proved the existence of uniform nano scaled metallic Ag NPs. By contrast, the UV irradiated Ag@AA-MMT-3 (Ag@AA-MMT-UV) showed a much better slow release property than Ag@AA-MMT-3 or Ag@MMT. The Ag@AA-MMT-UV showing a large inhibition zone and high inhibition ratio presented very good antibacterial property.

  5. Redox potentials and kinetics of the Ce 3+\\/Ce 4+ redox reaction and solubility of cerium sulfates in sulfuric acid solutions

    Microsoft Academic Search

    A. Paulenova; S. E. Creager; J. D. Navratil; Y. Wei

    2002-01-01

    Experimental work was performed with the aim of evaluating the Ce4+\\/Ce3+ redox couple in sulfuric acid electrolyte for use in redox flow battery (RFB) technology. The solubility of cerium sulfates in 0.1–4.0M sulfuric acid at 20–60°C was studied. A synergistic effect of both sulfuric acid concentration and temperature on the solubility of cerous sulfate was observed. The solubility of cerous

  6. The development of nickel silicide based alloy for sulfuric acid application

    NASA Astrophysics Data System (ADS)

    Zhang, Sanhong

    2000-10-01

    The present project has been supported by Chas S. Lewis Co. Inc. to try to develop a cast alloy that has acceptable mechanical properties and excellent resistance to corrosion by sulfuric acid over the entire concentration range (especially for the concentrations between 60 and 80 wt%) at their boiling temperatures. Also, the alloy should have good machinability and weldability, and be economically viable. It is known that Ni3Si-based alloys have good corrosion resistance in concentrated sulfuric acids, but they are very brittle. In the present study, Ni3Si-based alloys with Ti, Nb, Cu, Cr, and Mo additions have been cast and studied with SEM, DTA, AES, and optical microscopy. Their mechanical properties and corrosion resistance in boiling sulfuric acids with different heat treatments have been investigated. It has been found that alloys NiSi20Nb3B0.5, NiSi20.4Nb 2B0.5. and NiSi20.2Nb2.5B0.5 have acceptable mechanical properties, machinability, and weldability, and have better corrosion resistance in boiling 60%, 70%, and 80% sulfuric acid than any other existing alloys. The effects of Ti, Nb, Cu, Cr, and Mo additions on the microstructure and corrosion resistance of the alloys have been studied. It was found that Ti additions encouraged the formation of the Ni3Si beta phase, but the beta phase with Ti addition had very poor corrosion resistance. Nb addition increased the ductility and the corrosion resistance of the alloy. Cu, Cr, and Mo additions encouraged the formation of the alpha and gamma phases (the former phase usually decreased the corrosion resistance, the latter hurt mechanical properties). An investigation of the weldability of the alloys showed that the as-cast NiSi20Nb3B0.5 alloy could be successfully welded using 600°C preheat and NiSi20Nb3B0.5 welding rods produced by centrifugal casting. Effects of the G phase (Ni16Si7Nb6) on the corrosion resistance and mechanical properties, corrosion resistance mechanism, and polarization behavior of the alloys were also investigated.

  7. Corrosion behavior of niobium and Nb-25 wt% Ta alloy in sulfuric acid solutions

    SciTech Connect

    Robin, A.; Nunes, C.A. (Fundacao de Tecnologia Industrial, Centro de Materiais Refratanios, Polo Urbo, Industrial Gleba Al-6, 12600 Lorena, Sao Paulo (BR)); de Almeida, M.E. (Dept. de Quimica da Univ. Federal da Paraiba, CCEN, Cidade Univ., 58040 Joao Pessoa, Paraiba (BR))

    1991-06-01

    In this paper the corrosion behavior of niobium and Nb-25 wt% Ta alloy in H{sub 2} SO{sub 4} solutions has been studied. Using mass-loss techniques, the influences of H{sub 2}SO{sub 4} concentration, temperature, and exposure time have been examined. The Nb-Ta alloy is more corrosion resistant than pure niobium. The obtained corrosion data allowed the construction of iso-corrosion curves of both materials in sulfuric acid below and above the boiling point.

  8. Detection of Stratospheric Sulfuric Acid Aerosols with Polarization Lidar: Theory, Simulations, and Observations

    NASA Astrophysics Data System (ADS)

    Beyerle, Georg

    2000-09-01

    The derivation of backscatter ratio profiles from polarization lidar measurements is discussed. The method is based on differences in depolarization between molecular backscattering and backscattering from spherical aerosol particles. Simulations show that the polarization algorithms yield backscatter ratios with uncertainties comparable with those obtained by Klett s method, provided that the backscattering process is dominated by molecular scattering. The technique could be utilized for monitoring the stratospheric sulfuric acid aerosol layer during periods of background conditions. The polarization analysis method is discussed in light of simulation results and is applied to polarization lidar profiles observed during the ALBATROSS 1996 field measurement campaign.

  9. AC impedance measurement of cystine adsorption at mild steel\\/sulfuric acid interface as corrosion inhibitor

    Microsoft Academic Search

    Muzaffer Özcan

    2008-01-01

    Alternating current (AC) impedance measurements of mild steel\\/sulfuric acid interface in the absence and in the presence of\\u000a various concentrations of cystine (Cys–Cys) have been carried out in the 100 kHz–10 mHz frequency range. The results revealed\\u000a that Cys–Cys is a good and effective inhibitor for mild steel corrosion in 0.5 M H2SO4 and its percent inhibition efficiency changes with its concentration. Changes

  10. INFLUENCE OF DILUTE ACETIC ACID TREATMENTS ON SURVIVAL OF AMERICAN PONDWEED WINTER BUDS IN THE NEVADA IRRIGATION DISTRICT, CALIFORNIA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    American pondweed (Potamogeton nodosus Poir.) is commonly found in northern California irrigation canals. The purpose of this study was to test the hypothesis that exposure of American pondweed winter buds to dilute acetic acid under field conditions would result in reduced survivorship and subsequ...

  11. Ice Nucleation of Bare and Sulfuric Acid-coated Mineral Dust Particles and Implication for Cloud Properties

    SciTech Connect

    Kulkarni, Gourihar R.; Sanders, Cassandra N.; Zhang, Kai; Liu, Xiaohong; Zhao, Chun

    2014-08-27

    Ice nucleation properties of different dust species coated with soluble material are not well understood. We determined the ice nucleation ability of bare and sulfuric acid coated mineral dust particles as a function of temperature (-25 to -35 deg C) and relative humidity with respect to water (RHw). Five different mineral dust species: Arizona test dust (ATD), illite, montmorillonite, quartz and kaolinite were dry dispersed and size-selected at 150 nm and exposed to sulfuric acid vapors in the coating apparatus. The condensed sulfuric acid soluble mass fraction per particle was estimated from the cloud condensation nuclei activated fraction measurements. The fraction of dust particles nucleating ice at various temperatures and RHw was determined using a compact ice chamber. In water-subsaturated conditions, compared to bare dust particles, we found that only coated ATD particles showed suppression of ice nucleation ability while other four dust species did not showed the effect of coating on the fraction of particles nucleating ice. The results suggest that interactions between the dust surface and sulfuric acid vapor are important, such that interactions may or may not modify the surface via chemical reactions with sulfuric acid. At water-supersaturated conditions we did not observed the effect of coating, i.e. the bare and coated dust particles had similar ice nucleation behavior.

  12. Visualization of Imbalances in Sulfur Assimilation and Synthesis of Sulfur-Containing Amino Acids at the Single-Cell Level

    PubMed Central

    Hoffmann, Kristina; Grünberger, Alexander; Lausberg, Frank; Bott, Michael

    2013-01-01

    We describe genetically encoded sensors which transmit elevated cytosolic concentrations of O-acetyl serine (OAS) and O-acetyl homoserine (OAH)—intermediates of l-cysteine and l-methionine synthesis—into an optical output. The sensor pSenOAS3 elicits 7.5-fold-increased fluorescence in cultures of a Corynebacterium glutamicum strain that excrete l-cysteine. Determination of the cytosolic OAS concentration revealed an increase to 0.13 mM, whereas the concentration in the reference strain was below the detection limit, indicating that incorporation of assimilatory sulfur is limited in the strain studied. In another strain, overexpression of metX encoding homoserine acetyltransferase resulted in an 8-fold increase in culture fluorescence at a cytosolic OAH concentration of 0.76 mM. We also assayed for consequences of extracellular sulfur supply and observed a graded fluorescence increase at decreasing sulfur concentrations below 400 ?M. Overall, this demonstrates the usefulness of the sensors for monitoring intracellular sulfur availability. The sensors also enable monitoring at the single-cell level, and since related and close homologs of the transcription factor used in the constructed sensors are widespread among bacteria, this technology offers a new possibility of assaying in vivo for sulfur limitation and of doing this at the single-cell level. PMID:23995919

  13. Effectiveness of coagulation and acid precipitation processes for the pre-treatment of diluted black liquor.

    PubMed

    Garg, Anurag; Mishra, I M; Chand, S

    2010-08-15

    The effectiveness of coagulation (using aluminium-based chemicals and ferrous sulfate) and acid precipitation (using H(2)SO(4)) processes for the pre-treatment of diluted black liquor obtained from a pulp and paper mill is reported. Commercial alum was found to be the most economical among all the aluminium and ferrous salts used as a coagulant. A maximum removal of chemical oxygen demand (COD) (ca. 63%) and colour reduction (ca. 90%) from the wastewater (COD = 7000 mg l(-1)) at pH 5.0 was obtained with alum. During the acid precipitation process, at pH < 5.0, significant COD reductions (up to 64%) were observed. Solid residue obtained from the alum treatment at a temperature of 95 degrees C showed much better (3 times) settling rate than that for the residue obtained after treatment with the same coagulant at a temperature of 25 degrees C. The settling curves had three parts, namely, hindered, transition and compression zones. Tory plots were used to determine the critical height of suspension-supernatant interface that is used in the design of a clarifier-thickener unit. High heating values and large biomass fraction of the solid residues can encourage the fuel users to use this waste derived sludge as a potential renewable energy source. PMID:20430523

  14. Exploring Jupiter's icy moons with old techniques and big facilities - new insights on sulfuric acid hydrates

    NASA Astrophysics Data System (ADS)

    Maynard-Casely, H. E.; Avdeev, M.; Brand, H.; Wallwork, K.

    2013-12-01

    Sulfuric acid hydrates have been proposed to be abundant on the surface of Europa [1], and hence would be important planetary forming materials for this moon and its companions Ganymede and Callisto. Understanding of the surface features and subsurface of these moons could be advanced by firmer knowledge of the icy materials that comprise them [2], insight into which can be drawn from firmer knowledge of physical properties and phase behaviour of the candidate materials. We wish to present results from a study that started with the question ';What form of sulfuric acid hydrate would form on the surface of Europa'. The intrinsic hydrogen-domination of planetary ices, makes studying these materials with laboratory powder diffraction very challenging. Insights into their crystalline phase behavior and the extraction of a number of thermal and mechanical properties is often only accessible with high-flux synchrotron x-ray diffraction and utilization of the large scattering cross section with neutron diffraction. We have used the Powder Diffraction beamline at Australian synchrotron [4] and the Echidna (High-resolution neutron powder diffraction) instrument of the Australian Nuclear Science and Technology Organization, [5] to obtain an number of new insights into the crystalline phases formed from sulfruic acid and water mixtures. These instruments have enabled the discovery a new water-rich sulfuric acid hydrate form [6], improved structural characterisation of existing forms [7] and a charting the phase diagram of this fundamental binary system [8]. This has revealed exciting potential for understanding more about the surface of Europa from space, perhaps even providing a window into its past. [1] Carlson, R.W., R.E. Johnson, and M.S. Anderson, Science, 1999. 286(5437): p. 97-99. [2] Fortes, A.D. and M. Choukroun. Space Sci Rev, 2010. 153(1-4): p. 185-218. [3] Blake, D., et al., Space Sci Rev,, 2012. 170(1-4): p. 341-399. [4] Wallwork, K.S., Kennedy B. J. and Wang, D., AIP Conf Proc, 2007. 879: p. 879-882. [5] Liss, K.D., et al., Phys B-Cond Mat, 2006. 385-86: p. 1010-1012. [6] Maynard-Casely, H.E., K.S. Wallwork, and M. Avdeev, (In review). [7] Maynard-Casely, H.E., H.E.A. Brand, and K.S. Wallwork, J.of App.Cryst, 2012. 45: p.1198-1207. [8] Maynard-Casely, H.E., K.S. Wallwork, and H.E.A. Brand, (In Preparation). Stages of the crystal structure determination of sulfruic acid octahydrate a) the oxygen and sulfur postions were determined from the synchrotron x-ray data b) Once neutron diffraction data was collected Fourier difference methods were used to locate hydrogen positions to determine c) the full structure of sulfuric acid octahydrate.

  15. Microbial contributions to coupled arsenic and sulfur cycling in the acid-sulfide hot spring Champagne Pool, New Zealand

    PubMed Central

    Hug, Katrin; Maher, William A.; Stott, Matthew B.; Krikowa, Frank; Foster, Simon; Moreau, John W.

    2014-01-01

    Acid-sulfide hot springs are analogs of early Earth geothermal systems where microbial metal(loid) resistance likely first evolved. Arsenic is a metalloid enriched in the acid-sulfide hot spring Champagne Pool (Waiotapu, New Zealand). Arsenic speciation in Champagne Pool follows reaction paths not yet fully understood with respect to biotic contributions and coupling to biogeochemical sulfur cycling. Here we present quantitative arsenic speciation from Champagne Pool, finding arsenite dominant in the pool, rim and outflow channel (55–75% total arsenic), and dithio- and trithioarsenates ubiquitously present as 18–25% total arsenic. In the outflow channel, dimethylmonothioarsenate comprised ?9% total arsenic, while on the outflow terrace thioarsenates were present at 55% total arsenic. We also quantified sulfide, thiosulfate, sulfate and elemental sulfur, finding sulfide and sulfate as major species in the pool and outflow terrace, respectively. Elemental sulfur concentration reached a maximum at the terrace. Phylogenetic analysis of 16S rRNA genes from metagenomic sequencing revealed the dominance of Sulfurihydrogenibium at all sites and an increased archaeal population at the rim and outflow channel. Several phylotypes were found closely related to known sulfur- and sulfide-oxidizers, as well as sulfur- and sulfate-reducers. Bioinformatic analysis revealed genes underpinning sulfur redox transformations, consistent with sulfur speciation data, and illustrating a microbial role in sulfur-dependent transformation of arsenite to thioarsenate. Metagenomic analysis also revealed genes encoding for arsenate reductase at all sites, reflecting the ubiquity of thioarsenate and a need for microbial arsenate resistance despite anoxic conditions. Absence of the arsenite oxidase gene, aio, at all sites suggests prioritization of arsenite detoxification over coupling to energy conservation. Finally, detection of methyl arsenic in the outflow channel, in conjunction with increased sequences from Aquificaceae, supports a role for methyltransferase in thermophilic arsenic resistance. Our study highlights microbial contributions to coupled arsenic and sulfur cycling at Champagne Pool, with implications for understanding the evolution of microbial arsenic resistance in sulfidic geothermal systems. PMID:25414696

  16. Lead oxide as used in lead acid storage batteries, part one

    Microsoft Academic Search

    Orsino

    1986-01-01

    About 125 years ago a French scientist, Gaston Plante, placed two pieces of lead in diluted sulfuric acid solution and connected them to several primary battery cells and made the first secondary lead-acid battery cell. Plante had tried many other metals and other solvents but the combination of lead and sulfuric acid gave the strongest and longest sustained reverse current

  17. Studies on the enhancement of allergic lung sensitization by inhalation of ozone and sulfuric acid aerosol

    SciTech Connect

    Osebold, J.W.; Gershwin, L.J.; Zee, Y.C.

    1980-06-01

    Air pollutants were found to enhance the allergic sensitization of mice to an inhaled antigen. Aerosolized ovalbumin was used to minic the inhalation of an environmental allergen. In three experiments the antigenic contact was repeated at 4 to 7 times over a period of approximately a month. Groups of mice were intermittently exposed to ozone at 0.5 and 0.8 ppM, sulfuric acid aerosol (1 mg/m3), and a combination of the two air pollutants. Antigenically sensitized mice showed some evidence of atopic reactivity to the inhaled antigen, but the interpretation of these responses was difficult to evaluate by observation alone. Clear evidence of allergic sensitization was obtained by injecting the antigen intravenously and recording the instances of systemic anaphylaxis. Allergic mice demonstrated anaphylactic shock within a few minutes of the injection, and fatally shocked animals died within 20 to 40 min. Signficant increases in the levels of sensitization were obtained in animals exposed to ozone and the combination of ozone and sulfuric acid aerosol.

  18. Copper-Sulfate Pentahydrate as a Product of the Waste Sulfuric Acid Solution Treatment

    NASA Astrophysics Data System (ADS)

    Markovi?, Radmila; Stevanovi?, Jasmina; Avramovi?, Ljiljana; Nedeljkovi?, Dragutin; Jugovi?, Branimir; Staji?-Troši?, Jasna; Gvozdenovi?, Milica

    2012-12-01

    The aim of this study is synthesis of copper-sulfate pentahydrate from the waste sulfuric acid solution-mother liquor generated during the regeneration process of copper bleed solution. Copper is removed from the mother liquor solution in the process of the electrolytic treatment using the insoluble lead anodes alloyed with 6 mass pct of antimony on the industrial-scale equipment. As the result of the decopperization process, copper is removed in the form of the cathode sludge and is precipitated at the bottom of the electrolytic cell. By this procedure, the content of copper could be reduced to the 20 mass pct of the initial value. Chemical characterization of the sludge has shown that it contains about 90 mass pct of copper. During the decopperization process, the very strong poison, arsine, can be formed, and the process is in that case terminated. The copper leaching degree of 82 mass pct is obtained using H2SO4 aqueous solution with the oxygen addition during the cathode sludge chemical treatment at 80 °C ± 5 °C. Obtained copper salt satisfies the requirements of the Serbian Standard for Pesticide, SRPS H.P1. 058. Therefore, the treatment of waste sulfuric acid solutions is of great economic and environmental interest.

  19. Multiple inputs control sulfur-containing amino acid synthesis in Saccharomyces cerevisiae

    PubMed Central

    Sadhu, Meru J.; Moresco, James J.; Zimmer, Anjali D.; Yates, John R.; Rine, Jasper

    2014-01-01

    In Saccharomyces cerevisiae, transcription of the MET regulon, which encodes the proteins involved in the synthesis of the sulfur-containing amino acids methionine and cysteine, is repressed by the presence of either methionine or cysteine in the environment. This repression is accomplished by ubiquitination of the transcription factor Met4, which is carried out by the SCF(Met30) E3 ubiquitin ligase. Mutants defective in MET regulon repression reveal that loss of Cho2, which is required for the methylation of phosphatidylethanolamine to produce phosphatidylcholine, leads to induction of the MET regulon. This induction is due to reduced cysteine synthesis caused by the Cho2 defects, uncovering an important link between phospholipid synthesis and cysteine synthesis. Antimorphic mutants in S-adenosyl-methionine (SAM) synthetase genes also induce the MET regulon. This effect is due, at least in part, to SAM deficiency controlling the MET regulon independently of SAM's contribution to cysteine synthesis. Finally, the Met30 protein is found in two distinct forms whose relative abundance is controlled by the availability of sulfur-containing amino acids. This modification could be involved in the nutritional control of SCF(Met30) activity toward Met4. PMID:24648496

  20. Temperature dependence of single-bubble sonoluminescence threshold in sulfuric acid: An experimental study

    NASA Astrophysics Data System (ADS)

    Bandara, Vibodha; Herath, Prabhath; Nanayakkara, Asiri

    2015-06-01

    We experimentally investigated the temperature dependence of intensity of single-bubble sonoluminescence (SBSL) in 85 wt %. sulfuric acid. It was found that the intensity increases as temperature increases from 15 °C and 25 °C, confirming what has been predicted by A. Moshaii et al. [Phys. Rev. E 84, 046301 (2011), 10.1103/PhysRevE.84.046301] theoretically. This behavior, however, is completely opposite to what has been observed for water. Above 25 °C, the behavior of intensity of SBSL in sulfuric acid is found to be independent of the liquid temperature. Moreover, it was observed that as the temperature increases, contribution to total intensity from the UV portion of the spectrum increases while contribution from the visible portion decreases, indicating higher bubble temperatures at higher liquid temperatures. Results of this experiment further indicate that the intensity threshold at each temperature is not determined by the shape or the positional stability conditions but by the driving pressure at which the transition from SBSL to multibubble sonoluminescence (MBSL) takes place.

  1. Comparison of enzymatic reactivity of corn stover solids prepared by dilute acid, AFEX™, and ionic liquid pretreatments

    PubMed Central

    2014-01-01

    Background Pretreatment is essential to realize high product yields from biological conversion of naturally recalcitrant cellulosic biomass, with thermochemical pretreatments often favored for cost and performance. In this study, enzymatic digestion of solids from dilute sulfuric acid (DA), ammonia fiber expansion (AFEX™), and ionic liquid (IL) thermochemical pretreatments of corn stover were followed over time for the same range of total enzyme protein loadings to provide comparative data on glucose and xylose yields of monomers and oligomers from the pretreated solids. The composition of pretreated solids and enzyme adsorption on each substrate were also measured to determine. The extent glucose release could be related to these features. Results Corn stover solids from pretreatment by DA, AFEX, and IL were enzymatically digested over a range of low to moderate loadings of commercial cellulase, xylanase, and pectinase enzyme mixtures, the proportions of which had been previously optimized for each pretreatment. Avicel® cellulose, regenerated amorphous cellulose (RAC), and beechwood xylan were also subjected to enzymatic hydrolysis as controls. Yields of glucose and xylose and their oligomers were followed for times up to 120 hours, and enzyme adsorption was measured. IL pretreated corn stover displayed the highest initial glucose yields at all enzyme loadings and the highest final yield for a low enzyme loading of 3 mg protein/g glucan in the raw material. However, increasing the enzyme loading to 12 mg/g glucan or more resulted in DA pretreated corn stover attaining the highest longer-term glucose yields. Hydrolyzate from AFEX pretreated corn stover had the highest proportion of xylooligomers, while IL produced the most glucooligomers. However, the amounts of both oligomers dropped with increasing enzyme loadings and hydrolysis times. IL pretreated corn stover had the highest enzyme adsorption capacity. Conclusions Initial hydrolysis yields were highest for substrates with greater lignin removal, a greater degree of change in cellulose crystallinity, and high enzyme accessibility. Final glucose yields could not be clearly related to concentrations of xylooligomers released from xylan during hydrolysis. Overall, none of these factors could completely account for differences in enzymatic digestion performance of solids produced by AFEX, DA, and IL pretreatments. PMID:24910713

  2. Recovery of transplutonium elements from aqueous and water-ethanol solutions of sulfuric acid and their separation from other actinides

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1988-05-01

    The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on anion and cation exchangers in aqueous and water-ethanol solutions of sulfuric acid as a function of the various components of the solution has been investigated. It has been discovered that the presence of ethanol in sulfuric acid solutions causes an increase in the distribution coefficients both on cation exchangers and on anion exchangers. The possibility of the use of ion exchangers for the preconcentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements which form strong complexes with sulfate ions over a broad range of concentrations of sulfuric acid has been demonstrated.

  3. Acid hydrolysis and pretreatment of lignocellulosic substrates: Final subcontract report

    Microsoft Academic Search

    H. Grethlein; A. Converse; J. VickRoy; J. Holland; W. Grous; J. Ward

    1987-01-01

    This report presents findings on acid hydrolysis and pretreatment of lignocellulosic substrates. Acetone was incorporated as a major fluid component to promote the hydrolysis of wood in the presence of dilute sulfuric acid and water. The use of a novel cyclone reactor design was explored through computer simulation and prototype construction. An investigation of using sulfur dioxide near the critical

  4. Effect of Sulfuric and Triflic Acids on the Hydration of Vanadium Cations: An ab Initio Study.

    PubMed

    Sepehr, Fatemeh; Paddison, Stephen J

    2015-06-01

    Vanadium redox flow batteries (VRFBs) may be a promising solution for large-scale energy storage applications, but the crossover of any of the redox active species V(2+), V(3+), VO(2+), and VO2(+) through the ion exchange membrane will result in self-discharge of the battery. Hence, a molecular level understanding of the states of vanadium cations in the highly acidic environment of a VRFB is needed. We examine the effects of sulfuric and triflic (CF3SO3H) acids on the hydration of vanadium species as they mimic the electrolyte and functional group of perfluorosulfonic acid (PFSA) membranes. Hybrid density functional theory in conjunction with a continuum solvation model was utilized to obtain the local structures of the hydrated vanadium cations in proximity to H2SO4, CF3SO3H, and their conjugate anions. The results indicate that none of these species covalently bond to the vanadium cations. The hydration structure of V(3+) is more distorted than that of V(2+) in an acidic medium. The oxo-group of VO2(+) is protonated by either acid, in contrast to VO(2+) which is not protonated. The atomic partial charge of the four oxidation states of vanadium varies from +1.7 to +2.0. These results provide the local solvation structures of vanadium cations in the VRFBs environment that are directly related to the electrolytes stability and diffusion of vanadium ions into the membrane. PMID:25954916

  5. Evidence for incorporation of H2S in groundwater fulvic acids from stable isotope ratios and sulfur K-edge X-ray absorption near edge structure spectroscopy.

    PubMed

    Einsiedl, Florian; Mayer, Bernhard; Schäfer, Thorsten

    2008-04-01

    Groundwater samples collected in a shallow oxic and reduced deep groundwater system revealed the influence of dissolved sulfide on the chemical and isotopic composition of fulvic acid associated sulfur. Stable isotope compositions of groundwater sulfate and fulvic acid sulfur and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy data were used to determine the sources and processes affecting fulvic acid sulfur in the aquifer. A delta34S value of 2.2 per thousand for the shallow groundwater sulfate and a delta34S value of fulvic acids of 4.9 per thousand accompanied by a contribution of up to 49% of the most oxidized sulfur species (S+6) documented that fulvic acid sulfur is mainly derived from soil S compounds such as ester sulfates, with delta34S values similar to those of atmospheric sulfate deposition. In contrast, in the deep groundwater system with elevated delta34S values in groundwater sulfate of up to 20per thousand due to bacterial sulfate reduction, delta34S values in fulvic acid sulfur were negative and were up to 22per thousand lower compared to those of groundwater sulfate. Furthermore, reduced sulfur compounds constituted a significantly higher proportion of total fulvic acid sulfur in the deep groundwater compared to fulvic acids in shallow groundwater, supporting the hypothesis that fulvic acids act as a sink for dissolved hydrogen sulfide in the deep aquifer. Our results suggest that the combination of sulfur K edge XANES spectroscopy and stable isotope analysis on fulvic acids represents a powerful tool to elucidate the role of fulvic acids in the sulfur cycle in groundwater. PMID:18504978

  6. Surfactant control of gas transport and reactions at the surface of sulfuric acid.

    PubMed

    Park, Seong-Chan; Burden, Daniel K; Nathanson, Gilbert M

    2009-02-17

    Aerosol particles in the atmosphere are tiny chemical reactors that catalyze numerous reactions, including the conversion of benign gases into ozone-destroying ones. In the lower stratosphere, these particles are often supercooled mixtures of water and sulfuric acid. The different species present at the surface of these droplets (H(2)O, H(3)O(+), HSO(4)(-), H(2)SO(4), and SO(4)(2-)) stand at the "gas-liquid frontier"; as the first to be struck by impinging molecules, these species provide the initial environment for solvation and reaction. Furthermore, aerosol particles may contain a wide range of organic molecules, some of which migrate to the surface and coat the droplet. How do ambient gases dissolve in the droplet if it is coated with an organic layer? At one extreme, monolayer films of insoluble, long-chain alcohols can dramatically reduce gas transport, packing so tightly at the surface of water that they impede water evaporation by factors of 10,000 or more. Shorter chain surfactants are expected to pack less tightly, but we wondered whether these incomplete monolayers also block gas transport and whether this system could serve as a model for understanding the surfaces of atmospheric aerosol particles. To address these questions, our research focuses on small, soluble surfactants such as butanol and hexanol dissolved in supercooled sulfuric acid. These amphiphilic molecules spontaneously segregate to the surface and coat the acid but only to a degree. Gas-liquid scattering experiments reveal that these porous films behave in surprisingly diverse ways: they can impose a barrier (to N(2)O(5) hydrolysis), be "invisible" (to water evaporation), or even enhance gas uptake (of HCl). The transition from obstacle to catalyst can be traced to specific interactions between the surfactant and each gas. For example, the hydrolysis of N(2)O(5) may be impeded because of its large size and because alcohol molecules that straddle the interface limit contact between N(2)O(5) and its H(3)O(+) and H(2)O reaction partners. However, these same alcohol molecules assist HCl dissociation because the alcohol OH groups provide extra interfacial protonation sites. Interestingly, butanol does not impede water evaporation, in part because the butyl chains pack much more loosely than insoluble, long-chain surfactants. Through these investigations, we hope to gain insight into the mechanisms by which surfactants on sulfuric acid and other aqueous solutions affect transport and reactivity at the gas-liquid interface. PMID:19119820

  7. Stearoyl-CoA Desaturase-1: Is It the Link between Sulfur Amino Acids and Lipid Metabolism?

    PubMed Central

    Poloni, Soraia; Blom, Henk J.; Schwartz, Ida V. D.

    2015-01-01

    An association between sulfur amino acids (methionine, cysteine, homocysteine and taurine) and lipid metabolism has been described in several experimental and population-based studies. Changes in the metabolism of these amino acids influence serum lipoprotein concentrations, although the underlying mechanisms are still poorly understood. However, recent evidence has suggested that the enzyme stearoyl-CoA desaturase-1 (SCD-1) may be the link between these two metabolic pathways. SCD-1 is a key enzyme for the synthesis of monounsaturated fatty acids. Its main substrates C16:0 and C18:0 and products palmitoleic acid (C16:1) and oleic acid (C18:1) are the most abundant fatty acids in triglycerides, cholesterol esters and membrane phospholipids. A significant suppression of SCD-1 has been observed in several animal models with disrupted sulfur amino acid metabolism, and the activity of SCD-1 is also associated with the levels of these amino acids in humans. This enzyme also appears to be involved in the etiology of metabolic syndromes because its suppression results in decreased fat deposits (regardless of food intake), improved insulin sensitivity and higher basal energy expenditure. Interestingly, this anti-obesogenic phenotype has also been described in humans and animals with sulfur amino acid disorders, which is consistent with the hypothesis that SCD-1 activity is influenced by these amino acids, in particularly cysteine, which is a strong and independent predictor of SCD-1 activity and fat storage. In this narrative review, we discuss the evidence linking sulfur amino acids, SCD-1 and lipid metabolism. PMID:26046927

  8. Effect of sulfuric acid, oxygen, and hydrogen in high-temperature water on stress corrosion cracking of sensitized Type 304 stainless steel

    SciTech Connect

    Ruther, W.E.; Soppet, W.K.; Ayrault, G.; Kassner, T.F.

    1983-06-01

    The influence of dissolved oxygen and hydrogen and dilute sulfuric acid in 289/sup 0/C water on the stress-corrosion-cracking susceptibility of lightly and moderately sensitized Type 304 stainless steel was determined in constant-extension-rate tensile (CERT) tests. The CERT parameters and the fracture surface morphologies were correlated with the concentrations of dissolved oxygen and sulfate, and the electrochemical potentials of platinum and Type 304 stainless steel electrodes in simulated boiling-water reactor (BWR) environments. A particularly high susceptibility to intergranular cracking was found for the steel in the lightly sensitized condition at oxygen concentrations between approx. 0.05 and 0.2 ppM under slightly acidic conditions (pH approx. 6.0 at 25/sup 0/C), which may, in part, account for the pervasive nature of intergranular cracking in BWR piping systems. Scanning-transmission electron microscopy analyses revealed significant differences between samples in the lightly and the moderately sensitized condition with respect to the width, but not the depth, of the chromium-depleted region at the grain boundaries. The addition of 0.5 ppM hydrogen to the water had only a small mitigating effect on intergranular cracking in water containing oxygen and sulfuric acid at low concentrations; however, oxygen suppression to less than or equal to 0.05 ppM in the reactor-coolant water, by means of hydrogen additions to the feedwater, would be quite beneficial provided impurities are also maintained at very low levels.

  9. Nitric acid catalyzed hydrolysis of SO3 in the formation of sulfuric acid: A theoretical study

    NASA Astrophysics Data System (ADS)

    Long, Bo; Chang, Chun-Ran; Long, Zheng-Wen; Wang, Yi-Bo; Tan, Xing-Feng; Zhang, Wei-Jun

    2013-08-01

    The gas-phase hydrolysis of SO3 in the presence of one water molecule, two water molecules, and nitric acid is investigated utilizing high level quantum chemical methods and transition state theory. The calculated results demonstrate that nitric acid exerts a strong catalytic role in the hydrolysis of SO3 because the activated barrier of hydrolysis of SO3 with the assistance of nitric acid is reduced to about 3.7 kcal/mol, which is about 20 kcal/mol lower than that of the SO3 reaction with water relative to the respective pre-reactive complex.

  10. Amino acid nutrition of the red drum (Sciaenops ocellatus): development of an improved test diet and determination of the total sulfur amino acid requirement 

    E-print Network

    Moon, Hae Young

    1990-01-01

    AMINO ACID NUTRITION OF THE RED DRUM (SCIAENOPS OCELLATUS): DEVELOPMENT OF AN IMPROVED TEST DIET AND DETERMINATION OF THE TOTAL SULFUR AMINO ACID REQUIREMENT A Thesis by HAE YOUNG MOON Submitted to the Office of Graduate Studies of Texas A...&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1990 Major Subject: Wildlife and Fisheries Sciences AMINO ACID NUTRITION OF THE RED DRUM (SCIAENOPS OCELLATUS): DEVELOPMENT OF AN IMPROVED TEST DIET...

  11. Structural changes of Salix miyabeana cellulose fibres during dilute-acid steam explosion: impact of reaction temperature and retention time.

    PubMed

    Diop, Chérif Ibrahima Khalil; Lavoie, Jean-Michel; Huneault, Michel A

    2015-03-30

    Dilute-acid steam explosion of Salix miyabeana has been carried out to understand the effect of processing conditions, expressed through a severity factors (SFT), on the changes in cellulose fibre structures in a perspective of using these in polymer composites. This thermo-chemico-mechanical extraction leads to the isolation of cellulose fibres as observed by SEM images. Fibre length as well as length to diameter aspect ratios decreased with the severity of the treatment. Likewise, fibre whiteness diminished with an increasing severity factor, which could be a tangible effect of physical degradation. Variations in crystallinity seemed to be dependent upon the reaction temperature, generally decreasing with regards to retention time. Above a severity threshold, a structural disorganization was observed. Overall, dilute-acid steam explosion was shown to be a valuable cellulose extraction process that can provide a variety of fibre structures. PMID:25563939

  12. The Mechanism of Electropolishing of Niobium in Hydrofluoric-Sulfuric Acid Electrolyte

    SciTech Connect

    Tian, Hui; Corcoran, Sean; Reece, Charles; Kelley, Michael

    2008-07-01

    Niobium surfaces are commonly electropolished in an effort to obtain optimal smoothness for high-field superconducting radio-frequency cavity applications. We report the use of controlled electrochemical analysis techniques to characterize electropolishing of Nb in a sulfuric and hydrofluoric acid electrolyte. Through the use of a reference electrode, we are able to clearly distinguish the anode and cathode polarization potentials as well as the electrolyte voltage drop, which together sum to the applied power supply voltage. We then identify the temperature and HF concentration dependence of each potential. We also report the use of electrochemical impedance spectroscopy (EIS) on this system. EIS results are consistent with the compact salt film mechanism for niobium electropolishing (EP) in this electrolyte and are not consistent with either the porous salt film or the absorbate-acceptor mechanism. Microscopic understanding of the basic Nb EP mechanism is expected to provide an appro

  13. Role of O-acetylhomoserine sulfhydrylase in sulfur amino acid synthesis in various yeasts.

    PubMed

    Brzywczy, J; Paszewski, A

    1993-12-01

    Mutants defective in O-acetylhomoserine sulfhydrylase (OAH-SHLase) were obtained in five yeast strains representative of different yeast genera: Saccharomyces cerevisiae, Kluyveromyces lactis, Yarrowia lipolytica, Schizosaccharomyces pombe and Trichosporon cutaneum. In vitro, in all five strains, the enzyme also had O-acetylserine (OAS) sulfhydrylase activity so it is a 'bifunctional' OAH/OAS-SHLase (Yamagata, 1989). The enzyme was only found to be essential in S. cerevisiae (OAH SHLase-negative mutants are auxotrophs). Its impairment in K. lactis caused a slower growth rate and a decrease of the sulfur amino acid pool. In T. cutaneum only the pool was affected whereas in Y. lipolytica and S. pombe the lesion caused no change in the growth rate nor in the pool. In all strains where OAH SHLase-negative mutants were prototrophs, a monofunctional OAS sulhydrylase was detected. The results indicate that OAH SHLase may play different physiological roles in various yeasts. PMID:8154184

  14. Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte

    NASA Astrophysics Data System (ADS)

    Soneda, Y.; Yamashita, J.; Kodama, M.; Hatori, H.; Toyoda, M.; Inagaki, M.

    2006-03-01

    The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4 F/m2 in 18 M H2SO4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however, gave a featureless cyclic voltammogram in 18 M H2SO4 solution. In the case of exfoliated natural graphite, the intercalation of H2SO4 molecules is evidenced by redox peaks observed in the voltammograms in the same conditions. Therefore, a strong interaction between the H2SO4 molecules and the ExCF surface might be the reason for the origin of pseudo-capacitance with ExCF in H2SO4 electrolyte.

  15. The adsorption and stability of sulfur containing amino acids on Cu{5 3 1}

    NASA Astrophysics Data System (ADS)

    Thomsen, L.; Wharmby, M. T.; Riley, D. P.; Held, G.; Gladys, M. J.

    2009-05-01

    The adsorption of L-cysteine and L-methionine amino acids on a chiral Cu{5 3 1} surface was investigated with high resolution X-ray photoelectron spectroscopy (XPS) and carbon K-edge near edge X-ray absorption fine structure (NEXAFS) Spectroscopy using synchrotron radiation. XPS shows that at 300 K L-cysteine adsorbs through two oxygen, a nitrogen and a sulfur atom, in a four point 'quadrangular footprint', whereas L-methionine adsorbs through only two oxygen and a nitrogen atom in a 'triangular footprint'. NEXAFS was used to clarify the adsorption geometry of both molecules, which suggests a binding orientation to the top layer and second layer atoms in two different orientations associated with adsorption sites on {1 1 0} and {3 1 1} microfacets of the Cu{5 3 1} surface.

  16. Single-bubble sonoluminescence in sulfuric acid and water: bubble dynamics, stability, and continuous spectra.

    PubMed

    Puente, Gabriela F; Garcķa-Martķnez, Pablo; Bonetto, Fabiįn J

    2007-01-01

    We present theoretical calculations of an argon bubble in a liquid solution of 85%wt sulfuric acid and 15%wt water in single-bubble sonoluminescence. We used a model without free parameters to be adjusted. We predict from first principles the region in parameter space for stable bubble evolution, the temporal evolution of the bubble radius, the maximum temperature, pressures, and the light spectra due to thermal emissions. We also used a partial differential equation based model (hydrocode) to compute the temperature and pressure evolutions at the center of the bubble during maximum compression. We found the behavior of this liquid mixture to be very different from water in several aspects. Most of the models in sonoluminescence were compared with water experimental results. PMID:17358260

  17. Condensational growth and trace species scavenging in stratospheric sulfuric acid/water aerosol droplets

    NASA Technical Reports Server (NTRS)

    Tompson, Robert V., Jr.

    1991-01-01

    Stratospheric aerosols play a significant role in the environment. The composition of aerosols is believed to be a liquid solution of sulfuric acid and water with numerous trace species. Of these trace species, ozone in particular was recognized as being very important in its role of shielding the environment from harmful ultraviolet radiation. Also among the trace species are HCl and ClONO2, the so called chlorine reservoir species and various oxides of nitrogen. The quantity of stratospheric aerosol and its particle size distribution determines, to a large degree, the chemistry present in the stratosphere. Aerosols experience 3 types of growth: nucleation, condensation, and coagulation. The application of condensation investigations to the specific problem of stratospheric aerosols is discussed.

  18. Conversion of dilute-acid hydrolyzates of spruce and birch to ethanol by fed-batch fermentation

    Microsoft Academic Search

    Mohammad J. Taherzadeh; Claes Niklasson; Gunnar Lidén

    1999-01-01

    Fermentation techniques for conversion of dilute acid hydrolyzates were examined. Batch and fed-batch fermentations of hydrolyzates from spruce and birch woods were made in a lab-scale (3.31) anaerobic bioreactor using the yeast Saccharomyces cerevisiae. The spruce and birch hydrolyzates contained high initial concentrations of furfural (2.2 and 5.7 g\\/l) and 5-hydroxymethylfurfural (HMF, 7.3 and 2.4 g\\/l), and were found to

  19. Speciation of Heptavalent Technetium in Sulfuric Acid: Structural and Spectroscopic Studies.

    SciTech Connect

    Poineau, Frederic; Weck, Philippe F.; German, Konstantin; Maruk, Alesya; Kirakosyan, Gayane; Lukens, Wayne; Rego, Daniel B.; Sattelberger, Alfred P.; Czerwinski, Kenneth R.

    2010-06-10

    The speciation of Tc(VII) in 12 M sulfuric acid was studied by NMR, UV-visible and XAFS spectroscopy, experimental results were supported by DFT calculation and were in agreement with the formation of TcO{sub 3}OH(H{sub 2}O){sub 2}. In summary, the speciation of heptvalent technetium has been investigated in sulfuric acid. In 12 M H{sub 2}SO{sub 4}, a yellow solution is observed, and its {sup 99}Tc NMR spectrum is consistent with a heptavalent complex. The yellow solution was further characterized by EXAFS spectroscopy, and results are consistent with the formation of TcO{sub 3}(OH)(H{sub 2}O){sub 2}. No technetium heptoxide or sulfato- complexes were detected in these conditions. The molecular structure of TcO{sub 3}(OH)(H{sub 2}O){sub 2} has been optimized by DFT techniques, and the structural parameters are well in accordance with those found by XAFS spectroscopy. The experimental electronic spectra exhibit ligand-to-metal charge transfer transitions that have been assigned using TDDFT methods. Calculations demonstrate the theoretical electronic spectrum of TcO{sub 3}(OH)(H{sub 2}O){sub 2} to be in very good agreement with the experimental one. Recent experiments in 12 M H{sub 2}SO{sub 4} show the yellow solution to be very reactive in presence of reducing agents presumably forming low valent Tc species. Current spectroscopic works focus on the speciation of these species.

  20. Surface Layers on Chromium in Sulfuric Acid Solutions of Organic Substances: An X-ray Photoelectron Spectroscopy Study

    Microsoft Academic Search

    V. A. Safonov; E. N. Lubnin; L. N. Vykhodtseva; G. E. Chusova; Yu. M. Polukarov

    2001-01-01

    Surface layers formed at a contact of chromium with sulfuric acid solutions containing some organic substances (sodium oxalate, dimethylformamide, methanol) are analyzed by the X-ray photoelectron spectroscopy method. The layers are shown to contain products of deep destruction of organic molecules, i.e. carbon species and those containing functional groups. The data obtained point to the electrocatalytic activity of chromium in

  1. Efficacy of reducing sugar and phenol-sulfuric acid assays for analysis of soluble carbohydrates in feedstuffs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing sugar (RSA) and phenol–sulfuric acid (PSA) assays are commonly used to analyze water-soluble carbohydrates. However, questions have arisen as to their accuracy for measurement of feedstuffs with diverse carbohydrate profiles. This study evaluated the efficacy of RSA and PSA as they would co...

  2. Quantitative trait locus analysis of seed sulfur containing amino acids in two recombinant inbred line populations of soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean (Glycine max (L.) Merr.) is a major source of plant protein for humans and livestock. Low levels of sulfur containing amino acids (cysteine and methionine) in soybean protein is the main limitation of soybean meal as animal food. The objectives of this study were to identify and validate Q...

  3. A new reaction model for the catalytic effect of silver ions on chalcopyrite leaching in sulfuric acid solutions

    Microsoft Academic Search

    Naoki Hiroyoshi; Masatoshi Arai; Hajime Miki; Masami Tsunekawa; Tsuyoshi Hirajima

    2002-01-01

    Chalcopyrite leaching in sulfuric acid solutions depends on the redox potential determined by the concentration ratio of ferric to ferrous ions, and the leaching rate is higher at redox potentials below a critical value. Previously, the authors have proposed a reaction model to interpret this phenomenon. The present study applied the model to interpret the catalytic effect of silver ions

  4. Chemical heat pump cost-effectiveness evaluation. Final report. [Methanolated-salt and sulfuric acid heat pumps

    Microsoft Academic Search

    R. Gorman; P. Moritz; W. Standley; T. OGorman

    1981-01-01

    The objective of the study was to compare the cost and energy effectiveness of existing heat pump (CHP) concepts with a baseline of conventional energy technologies and a group of near-term emerging energy technologies with which CHPs are expected to compete. Methanolated-salt and sulfuric acid CHPs were evaluated functioning as the primary space conditioning (HVAC) unit of both a standard

  5. Laboratory Measurements of the 2–4 mm Opacity of Sulfuric Acid Vapor Under Simulated Venus Conditions

    NASA Astrophysics Data System (ADS)

    Steffes, P. G.

    2015-04-01

    For over 30 years sulfuric acid vapor has been recognized as a major source of the microwave and millimeter-wave absorption in the atmosphere of Venus. This paper describes a new laboratory measurement campaign to characterize the 2–4 mm opacity.

  6. Corrosion inhibition and adsorption behavior of methionine on mild steel in sulfuric acid and synergistic effect of iodide ion

    Microsoft Academic Search

    E. E. Oguzie; Y. Li; F. H. Wang

    2007-01-01

    The corrosion inhibition of mild steel in sulfuric acid by methionine (MTI) was investigated using electrochemical techniques. The effect of KI additives on corrosion inhibition efficiency was also studied. The results reveal that MTI inhibited the corrosion reaction by adsorption onto the metal\\/solution interface. Inhibition efficiency increased with MTI concentration and synergistically increased in the presence of KI, with an

  7. Laboratory-measured nucleation rates of sulfuric acid and water binary homogeneous nucleation from the SO2 + OH reaction

    E-print Network

    Lee, Shan-Hu

    binary homogeneous nucleation (BHN) system is the most important atmospheric nucle- ation system, but there are only a limited number of experimental studies on this system [Wyslouzil et al., 1991; Viisanen et alLaboratory-measured nucleation rates of sulfuric acid and water binary homogeneous nucleation from

  8. Influence of sulfur-amino acid content variation in plant vs animal protein on serum and tissue lipids in rats

    Microsoft Academic Search

    Susan M. Potter; Constance V. Kies

    1990-01-01

    The objective of the study was to determine the effects of methionine and cysteine supplementation of soy protein isolate and casein on serum and tissue lipid levels in rats. Sixty male, weanling, Wistar-Kyoto rats were fed two sources of protein (casein or soy protein isolate) and three variations of sulfur-amino acid supplementation (none, methionine, or cysteine). At this level of

  9. Impedance Studies of Ru Oxide Reduction in Sulfuric Acid Pranav P. Sharma and Ian Ivar Suni*,z

    E-print Network

    Suni, Ian Ivar

    predicted by its Pourbaix diagram. Several research groups have proposed cathodic treatments prior to Cu to Cu or Ag electrodeposition,12-17 thereby enhancing nucleation and adhesion. However, these methodsImpedance Studies of Ru Oxide Reduction in Sulfuric Acid Pranav P. Sharma and Ian Ivar Suni

  10. A Xanthomonas Pathogenicity Locus Is Induced by Sucrose and Sulfur-Containing Amino Acids.

    PubMed Central

    Schulte, R; Bonas, U

    1992-01-01

    Expression of hrp (hypersensitive reaction and pathogenicity) genes from Xanthomonas campestris pv vesicatoria is suppressed in complex media but induced in the plant. We examined the effects of macronutrients on transcription of hrp-gusA ([beta]-glucuronidase) fusions by growth of the bacteria in defined medium. Modified MM1 minimal medium, supplemented with casamino acids, was able to induce hrpF strongly when sucrose or fructose was added as a carbon source. However, high concentrations of casamino acids suppressed hrpF induction. Sulfur-containing amino acids were required for induction, with methionine induction being comparable to induction in plants. Both sucrose and methionine were required for induction. Induction in medium optimal for hrpF induction, designated XVM1, occurred at pH 5.5 to pH 7.5. High concentrations of phosphate or sodium chloride suppressed gene activation. Gene induction was inhibited by succinate, citrate, pyruvate, and glutamine. Expression levels of different hrp loci from X. c. vesicatoria in XVM1 varied, dependent on the genetic background of the Xanthomonas strain used. The results suggest that several control mechanisms might be involved in the expression of hrp genes. PMID:12297631

  11. Sulfur-containing amino acids as precursors of thiols in anoxic coastal sediments.

    PubMed

    Kiene, R P; Malloy, K D; Taylor, B F

    1990-01-01

    Sulfur-containing amino acids were examined as precursors for thiols in anoxic coastal sediments. Substrates (10 to 100 muM) were anaerobically incubated with sediment slurries; thiols were assayed as isoindole derivatives by high-performance liquid chromatography; and microbial transformations of thiols, in contrast to their chemical binding by sediment particles, were identified by inhibition with a mixture of chloramphenicol and tetracycline. Methionine and homocysteine were transformed to methanethiol and 3-mercaptopropionate (3-MPA); methionine stimulated mainly methanethiol production, whereas homocysteine generated more 3-MPA than methanethiol. 2-Keto-4-methiolbutyrate yielded results similar to those with methionine, indicating that demethiolation yields methanethiol at the keto-acid level. Glutathione gave rise to cysteine, which was further transformed to 3-mercaptopyruvate and thence to mercaptoacetate and mercaptoethanol. Mercaptoethanol was oxidized to mercaptoacetate, which was biologically consumed. In conclusion, sulfurcontaining amino acids contribute to the range of thiols that occur in anoxic coastal sediments. New metabolic and environmental transformations were identified: the production of 3-MPA as a metabolite of methionine and the transformation of mercaptopyruvate to mercaptoethanol and mercaptoacetate. PMID:16348088

  12. Processing of LEU targets for {sup 99}Mo production -- Dissolution of metal foils by nitric-acid/sulfuric-acid mixtures

    SciTech Connect

    Srinivasan, B.; Leonard, R.A.; Aase, S. [and others

    1995-09-01

    The first step in processing low-enriched uranium (LEU) targets for production of {sup 99}Mo is to dissolve the neutron-irradiated uranium foil coming from the reactor. Appropriate conditions for dissolving the foils were determined by measuring the dissolution rates for uranium foil over a wide range of temperatures and acid concentrations. On the basis of these dissolution rates, the process chemistry, and a model that integrates dissolution rates as a function of temperature and composition, a closed stainless-steel dissolver was designed, built, and tested for dissolving up to 18 g of uranium foil. The results were quite successful, with the uranium foil being dissolved within one hour as desired. To do this, the dissolver temperature must be in the range from 97 to 102 C, and the dissolver solution (cocktail) must have a composition of 3M nitric acid and 2M sulfuric acid. The final dissolver solution is subsequently processed to separate {sup 99}Mo from uranium, fission products, and other elements.

  13. Variation of S/G Ratio and Lignin Content in a Populus Family Influences the Release of Xylose by Dilute Acid Hydrolysis.

    SciTech Connect

    Davison, Brian H [ORNL; Drescher, Sadie R [ORNL; Tuskan, Gerald A [ORNL; Davis, Dr. Mark F. [National Renewable Energy Laboratory (NREL); Nghiem, Nhuan Phu [ORNL

    2006-01-01

    Wood samples from second generation Populus cross were shown to have different lignin contents and S/G ratios (S: syringyl-like lignin structures; G: guaiacyl-like lignin structures). The lignin contents varied from 22.7% to 25.8% and the S/G ratio from 1.8 to 2.3. Selected samples spanning these ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions were chosen for partial hydrolysis of the hemicellulosic fraction to maximize the expression of variation among samples. The results indicated that both lignin contents and S/G ratio significantly affected the yield of xylose. For example, the xylose yield of the 25.8% lignin and 2.3 S/G (hihg lignin, high S/G) sample produced 30% of the theoretical yield, whereas the xylose yield of the 22.7% lignin and 1.8 S/G (low lignin, low S/G) was 55% of the theoretical value. These results indicate that lignin content and composition among genetic variants within a single species can influence the hydrolyzability of the biomass.

  14. Enhancement of total sugar and lignin yields through dissolution of poplar wood by hot water and dilute acid flowthrough pretreatment

    PubMed Central

    2014-01-01

    Background Pretreatment is a vital but expensive step in biomass biofuel production. Overall, most of this past effort has been directed at maximizing sugar yields from hemicellulose and cellulose through trials with different chemicals, operating conditions, and equipment configurations. Flowthrough pretreatment provides a promising platform to dissolution of lignocellulosic biomass to generate high yields of fermentable sugars and lignin for biofuels productions. Results Dissolution of xylan, lignin, and cellulose from poplar wood were significantly enhanced by water-only and dilute acid (0.05% w/w, H2SO4) flowthrough pretreatment when the temperature was raised from 200°C to 280°C over a range of flow rates 10-62.5 mL/min, resulting in more than 98% solid removal. Up to 40% of original xylan was converted to xylose in the hydrolyzate and the rest xylan was solubilized into xylooligomers with negligible furfural formation. Up to 100% cellulose was removed into hydrolyzate with the highest glucose yield of 60% and low 5-hydroxymethylfurfural (5-HMF) formation. The maximal recovered insoluble lignin and soluble lignin were 98% and 15% of original lignin, respectively. In addition, enzymatic hydrolysis of pretreated whole slurries was characterized under various enzyme loadings with or without Bovine serum albumin (BSA) treatment. More than 90% glucose yield and 95% xylose yield were obtained from enzymatic hydrolysis of dilute acid pretreated whole slurries with 10 mg protein Ctec 2 with 2 mg Htec2/g glucan?+?xylan. Conclusions Nearly complete dissolution of whole biomass was realized through water-only and dilute acid flowthrough pretreatment under tested conditions. Temperature was considered as the most significant factor for cellulose degradation. The cellulose removal significantly increased as temperature reached 240°C for water-only and 220°C for dilute acid. Dilute acid pretreatment resulted in higher yields of recovered xylan and cellulose as monomeric sugars in the hydrolyzate than that for water-only pretreatment. Enzymes readily hydrolyzed the degraded cellulose and xylooligomers in pretreatment hydrolysate. Results suggested that kinetics controlled the flowthrough pretreatment of biomass dissolution, which was also affected by flow rate to certain extent. PMID:24936209

  15. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  16. 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.

    PubMed

    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. PMID:18561128

  17. Optimization and kinetic analysis on the sulfuric acid - Catalyzed depolymerization of wheat straw.

    PubMed

    Wu, Qian-Qian; Ma, Yu-Long; Chang, Xuan; Sun, Yong-Gang

    2015-09-20

    The objectives of this work were to optimize the experimental condition and to study the kinetic behavior of wheat straw depolymerization with sulfuric acid (2wt%, 3wt%, and 4wt%) at different temperatures (120°C, 130°C, and 140°C). The two-fraction kinetic model was obtained for the prediction of the generations of product and by-product during depolymerization. The kinetic parameters of the two-fraction model were analyzed using an Arrhenius-type equation. Applying the kinetic two-fraction model, the optimum condition for wheat straw depolymerization was 3wt% H2SO4 at 130°C for 75min, which yielded a high concentration of fermentable sugars (xylose 8.934g/L, glucose 1.363g/L, and arabinose 1.203g/L) and low concentrations of microbial inhibitors (furfural 0.526g/L and acetic acid 1.192g/L). These results suggest that the model obtained in this study can satisfactorily describe the formation of degradation products and the depolymerization mechanism of wheat straw. PMID:26050891

  18. Reversible formation of ammonium persulfate/sulfuric acid graphite intercalation compounds and their peculiar Raman spectra.

    PubMed

    Dimiev, Ayrat M; Bachilo, Sergei M; Saito, Riichiro; Tour, James M

    2012-09-25

    Graphite intercalation compounds (GICs) can be considered stacks of individual doped graphene layers. Here we demonstrate a reversible formation of sulfuric acid-based GICs using ammonium persulfate as the chemical oxidizing agent. No covalent chemical oxidation leading to the formation of graphite oxide occurs, which inevitably happens when other compounds such as potassium permanganate are used to charge carbon layers. The resulting acid/persulfate-induced stage-1 and stage-2 GICs are characterized by suppression of the 2D band in the Raman spectra and by unusually strong enhancement of the G band. The G band is selectively enhanced at different doping levels with different excitations. These observations are in line with recent reports for chemically doped and gate-modulated graphene and support newly proposed theories of Raman processes. At the same time GICs have some advantageous differences over graphene, which are demonstrated in this report. Our experimental observations, along with earlier reported data, suggest that at high doping levels the G band cannot be used as the reference peak for normalizing Raman spectra, which is a commonly used practice today. A Fermi energy shift of 1.20-1.25 eV and ?1.0 eV was estimated for the stage-1 and stage-2 GICs, respectively, from the Raman and optical spectroscopy data. PMID:22880798

  19. Effects of vine water status on dimethyl sulfur potential, ammonium, and amino acid contents in Grenache Noir grapes (Vitis vinifera).

    PubMed

    De Royer Dupré, N; Schneider, R; Payan, J C; Salanēon, E; Razungles, A

    2014-04-01

    We studied the effect of vine water status on the dimethyl sulfur potential (DMSP), ammonium, and amino acid contents of the berry during the maturation of Grenache Noir grapes. Water deficit increased the accumulation of amino acids in berries and favored yeast assimilable amino nitrogen. Similarly, ammonium content was higher in berries from vines subjected to moderate water deficit. DMSP content followed the same trend as yeast assimilable amino acid content, with higher concentrations observed in the berries of vines subjected to water deficit. The high DMSP and yeast assimilable nitrogen contents of musts from vines subjected to water deficit resulted in a better preservation of DMSP during winemaking. The wines produced from these musts had a higher DMSP level and would therefore probably have a higher aroma shelf life, because the DMSP determines the rate of release of dimethyl sulfur during wine storage, and this compound enhances fruity notes. PMID:24611597

  20. Modified method for determination of sulfur metabolites in plant tissues by stable isotope dilution-based liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Chang, Ya-Lan; Hsieh, Chin-Lin; Huang, Yao-Moan; Chiou, Wen-Liang; Kuo, Yueh-Hsiung; Tseng, Mei-Hwei

    2013-11-01

    A wide variety of sulfur metabolites play important roles in plant functions. We have developed a precise and sensitive method for the simultaneous measurement of several sulfur metabolites based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and (34)S metabolic labeling of sulfur-containing metabolites in Arabidopsis thaliana seedlings. However, some sulfur metabolites were unstable during the extraction procedure. Our proposed method does not allow for the detection of the important sulfur metabolite homocysteine because of its instability during sample extraction. Stable isotope-labeled sulfur metabolites of A. thaliana shoot were extracted and utilized as internal standards for quantification of sulfur metabolites with LC-MS/MS using S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), methionine (Met), glutathione (GSH), and glutathione disulfide (GSSG) as example metabolites. These metabolites were detected using electrospray ionization in positive mode. Standard curves were linear (r(2)>0.99) over a range of concentrations (SAM 0.01-2.0?M, SAH 0.002-0.10?M, Met 0.05-4.0?M, GSH 0.17-20.0?M, GSSG 0.07-20.0?M), with limits of detection for SAM, SAH, Met, GSH, and GSSG of 0.83, 0.67, 10, 0.56, and 1.1nM, respectively; and the within-run and between-run coefficients of variation based on quality control samples were less than 8%. PMID:23911527

  1. Impact of dual temperature profile in dilute acid hydrolysis of spruce for ethanol production

    PubMed Central

    2010-01-01

    Background The two-step dilute acid hydrolysis (DAH) of softwood is costly in energy demands and capital costs. However, it has the advantage that hydrolysis and subsequent removal of hemicellulose-derived sugars can be carried out under conditions of low severity, resulting in a reduction in the level of sugar degradation products during the more severe subsequent steps of cellulose hydrolysis. In this paper, we discuss a single-step DAH method that incorporates a temperature profile at two levels. This profile should simulate the two-step process while removing its major disadvantage, that is, the washing step between the runs, which leads to increased energy demand. Results The experiments were conducted in a reactor with a controlled temperature profile. The total dry matter content of the hydrolysate was up to 21.1% w/w, corresponding to a content of 15.5% w/w of water insoluble solids. The highest measured glucose yield, (18.3 g glucose per 100 g dry raw material), was obtained after DAH cycles of 3 min at 209°C and 6 min at 211°C with 1% H2SO4, which resulted in a total of 26.3 g solubilized C6 sugars per 100 g dry raw material. To estimate the remaining sugar potential, enzymatic hydrolysis (EH) of the solid fraction was also performed. EH of the solid residue increased the total level of solubilized C6 sugars to a maximum of 35.5 g per 100 g dry raw material when DAH was performed as described above (3 min at 210°C and 2 min at 211°C with 1% H2SO4). Conclusion The dual-temperature DAH method did not yield decisively better results than the single-temperature, one-step DAH. When we compared the results with those of earlier studies, the hydrolysis performance was better than with the one-step DAH but not as well as that of the two-step, single-temperature DAH. Additional enzymatic hydrolysis resulted in lower levels of solubilized sugars compared with other studies on one-step DAH and two-step DAH followed by enzymatic hydrolysis. A two-step steam pretreatment with EH gave rise to a considerably higher sugar yield in this study. PMID:20594309

  2. Protein–Protein Interactions in Dilute to Concentrated Solutions: ?-Chymotrypsinogen in Acidic Conditions

    PubMed Central

    2015-01-01

    Protein–protein interactions were investigated for ?-chymotrypsinogen by static and dynamic light scattering (SLS and DLS, respectively), as well as small-angle neutron scattering (SANS), as a function of protein and salt concentration at acidic conditions. Net protein–protein interactions were probed via the Kirkwood–Buff integral G22 and the static structure factor S(q) from SLS and SANS data. G22 was obtained by regressing the Rayleigh ratio versus protein concentration with a local Taylor series approach, which does not require one to assume the underlying form or nature of intermolecular interactions. In addition, G22 and S(q) were further analyzed by traditional methods involving fits to effective interaction potentials. Although the fitted model parameters were not always physically realistic, the numerical values for G22 and S(q ? 0) were in good agreement from SLS and SANS as a function of protein concentration. In the dilute regime, fitted G22 values agreed with those obtained via the osmotic second virial coefficient B22 and showed that electrostatic interactions are the dominant contribution for colloidal interactions in ?-chymotrypsinogen solutions. However, as protein concentration increases, the strength of protein–protein interactions decreases, with a more pronounced decrease at low salt concentrations. The results are consistent with an effective “crowding” or excluded volume contribution to G22 due to the long-ranged electrostatic repulsions that are prominent even at the moderate range of protein concentrations used here (<40 g/L). These apparent crowding effects were confirmed and quantified by assessing the hydrodynamic factor H(q ? 0), which is obtained by combining measurements of the collective diffusion coefficient from DLS data with measurements of S(q ? 0). H(q ? 0) was significantly less than that for a corresponding hard-sphere system and showed that hydrodynamic nonidealities can lead to qualitatively incorrect conclusions regarding B22, G22, and static protein–protein interactions if one uses only DLS to assess protein interactions. PMID:24810917

  3. Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

    PubMed Central

    Sperandio, Brice; Polard, Patrice; Ehrlich, Dusko S.; Renault, Pierre; Guédon, Eric

    2005-01-01

    Cysteine and methionine availability influences many processes in the cell. In bacteria, transcription of the specific genes involved in the synthesis of these two amino acids is usually regulated by different mechanisms or regulators. Pathways for the synthesis of cysteine and methionine and their interconversion were experimentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food. A new gene, yhcE, was shown to be involved in methionine recycling to cysteine. Surprisingly, 18 genes, representing almost all genes of these pathways, are under the control of a LysR-type activator, FhuR, also named CmbR. DNA microarray experiments showed that FhuR targets are restricted to this set of 18 genes clustered in seven transcriptional units, while cysteine starvation modifies the transcription level of several other genes potentially involved in oxidoreduction processes. Purified FhuR binds a 13-bp box centered 46 to 53 bp upstream of the transcriptional starts from the seven regulated promoters, while a second box with the same consensus is present upstream of the first binding box, separated by 8 to 10 bp. O-Acetyl serine increases FhuR binding affinity to its binding boxes. The overall view of sulfur amino acid metabolism and its regulation in L. lactis indicates that CysE could be a master enzyme controlling the activity of FhuR by providing its effector, while other controls at the enzymatic level appear to be necessary to compensate the absence of differential regulation of the genes involved in the interconversion of methionine and cysteine and other biosynthesis genes. PMID:15901700

  4. First online measurements of sulfuric acid gas in modern heavy-duty diesel engine exhaust: implications for nanoparticle formation.

    PubMed

    Arnold, F; Pirjola, L; Rönkkö, T; Reichl, U; Schlager, H; Lähde, T; Heikkilä, J; Keskinen, J

    2012-10-16

    To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes. PMID:23035617

  5. Thermochemical destruction of asbestos-containing roofing slate and the feasibility of using recycled waste sulfuric acid.

    PubMed

    Nam, Seong-Nam; Jeong, Seongkyeong; Lim, Hojoo

    2014-01-30

    In this study, we have investigated the feasibility of using a thermochemical technique on ?17% chrysotile-containing roofing sheet or slate (ACS), in which 5N sulfuric acid-digestive destruction was incorporated with 10-24-h heating at 100°C. The X-ray diffraction (XRD) and the polarized light microscopy (PLM) results have clearly shown that raw chrysotile asbestos was converted to non-asbestiform material with no crystallinity by the low temperature thermochemical treatment. As an alternative to the use of pricey sulfuric acid, waste sulfuric acid discharged from a semiconductor manufacturing process was reused for the asbestos-fracturing purpose, and it was found that similar removals could be obtained under the same experimental conditions, promising the practical applicability of thermochemical treatment of ACWs. A thermodynamic understanding based on the extraction rates of magnesium and silica from a chrysotile structure has revealed that the destruction of chrysotile by acid-digestion is greatly influenced by the reaction temperatures, showing a 80.3-fold increase in the reaction rate by raising the temperature by 30-100°C. The overall destruction is dependent upon the breaking-up of the silicon-oxide layer - a rate-limiting step. This study is meaningful in showing that the low temperature thermochemical treatment is feasible as an ACW-treatment method. PMID:24361492

  6. Exogenous application of 5-aminolevulinic acid increases the transcript levels of sulfur transport and assimilatory genes, sulfate uptake, and cysteine and glutathione contents in Arabidopsis thaliana

    Microsoft Academic Search

    Akiko Maruyama-Nakashita; Masami Yokota Hirai; Shigeyuki Funada; Shoichi Fueki

    2010-01-01

    5-Aminolevulinic acid (ALA), a key precursor of porphyrin biosynthesis, promotes plant growth and crop yields. Although ALA is known to promote carbon fixation and nitrogen assimilation in plants, the effects of ALA on sulfur assimilation have not been determined. In the present study, we analyzed the effect of ALA on sulfur assimilation. We used a fusion gene construct consisting of

  7. Specificity of cysteine sulfinate decarboxylase (CSD) for sulfur-containing amino-acids.

    PubMed

    Do, K Q; Tappaz, M L

    1996-04-01

    Cysteine sulfinate decarboxylase (CSD) which decarboxylates cysteine sulfinic acid (CSA) to form hypotaurine is thought to be involved in the biosynthesis of taurine. It was recently localized in astrocytes in the cerebellum and hippocampus by immunocytochemistry. Another sulfur-containing amino-acid (SCAA), homocysteic acid (HCA), was also found in astrocytes in these regions. We therefore investigated the specificity of CSD vs CSA and HCA as well as the related analogs homocysteine sulfinic acid (HCSA) and cysteic acid (CA). CSD was immunotrapped from brain and liver tissue supernatant using a specific CSD antiserum and Protein-A Sepharose. It was then incubated with the L-form of the various SCAA. Reaction products were identified and quantified by pre-column o-phthalaldehyde derivatization HPLC. CA and HCA from 2.5 to 25 mM inhibited the formation of hypotaurine from CSA (0.25 mM). Moreover, the inhibition curves were parallel for liver and brain CSD. CA or HCA (25 mM) elicited a near-total inhibition. HCSA did not produce a significant inhibition up to 25 mM. Incubation with 25 mM CSA or CA led to the formation of hypotaurine and taurine, respectively. The ratio of formation of taurine to that of hypotaurine was similar for CSD from liver and brain. In contrast no homotaurine, the decarboxylated reaction product of HCA, could be detected following incubation with 25 mM HCA. According to the sensitivity of the HPLC analysis this indicates that the decarboxylation of HCA, if any, was 130-fold and 50-fold less than that of CSA by CSD from liver and brain, respectively, in our experimental conditions. Similarly, following incubation with HCSA, no new peak appeared on the chromatogram when compared to a blank sample. These results show that CSD from either brain or liver has a high specificity for CSA and CA, which are the SCAA involved in the biosynthesis of taurine. HCA is an inhibitor of CSD but does not appear to be a substrate for CSD in vitro. HCSA is neither a substrate nor an inhibitor of CSD in vitro. Accordingly, CSD is unlikely to play a role in the metabolism of HCA or HCSA in vivo. PMID:8740442

  8. Development of an estimation model for the evaluation of the energy requirement of dilute acid pretreatments of biomass?

    PubMed Central

    Mafe, Oluwakemi A.T.; Davies, Scott M.; Hancock, John; Du, Chenyu

    2015-01-01

    This study aims to develop a mathematical model to evaluate the energy required by pretreatment processes used in the production of second generation ethanol. A dilute acid pretreatment process reported by National Renewable Energy Laboratory (NREL) was selected as an example for the model's development. The energy demand of the pretreatment process was evaluated by considering the change of internal energy of the substances, the reaction energy, the heat lost and the work done to/by the system based on a number of simplifying assumptions. Sensitivity analyses were performed on the solid loading rate, temperature, acid concentration and water evaporation rate. The results from the sensitivity analyses established that the solids loading rate had the most significant impact on the energy demand. The model was then verified with data from the NREL benchmark process. Application of this model on other dilute acid pretreatment processes reported in the literature illustrated that although similar sugar yields were reported by several studies, the energy required by the different pretreatments varied significantly.

  9. Hydrometallurgical process for zinc recovery from electric arc furnace dust (EAFD): part I: Characterization and leaching by diluted sulphuric acid.

    PubMed

    Oustadakis, P; Tsakiridis, P E; Katsiapi, A; Agatzini-Leonardou, S

    2010-07-15

    The present paper is the first of a series of two articles dealing with the development of an integrated process for the recovery of zinc from electric arc furnace dust (EAFD), a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Part I presents the EAFD characterization and its leaching process by diluted sulphuric acid, whereas Part II deals with the purification of the leach liquor and the recovery of zinc by solvent extraction/electrowinning. The characterization of the examined electric arc furnace dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The leaching process was based on the Zn extraction with diluted sulphuric acid from EAFD under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The zinc recovery efficiency on the basis of EAFD weight reached 80%. X-ray diffraction and scanning electron microscopy were used for the characterization of the leached residues. PMID:20129730

  10. Changing trends in sulfur emissions in Asia: implications for acid deposition, air pollution, and climate.

    PubMed

    Carmichael, Gregory R; Streets, David G; Calori, Giuseppe; Amann, Markus; Jacobson, Mark Z; Hansen, James; Ueda, Hiromasa

    2002-11-15

    In the early 1990s, it was projected that annual SO2 emissions in Asia might grow to 80-110 Tg yr(-1) by 2020. Based on new high-resolution estimates from 1975 to 2000, we calculate that SO2 emissions in Asia might grow only to 40-45 Tg yr(-1) by 2020. The main reason for this lower estimate is a decline of SO2 emissions from 1995 to 2000 in China, which emits about two-thirds of Asian SO2. The decline was due to a reduction in industrial coal use, a slowdown of the Chinese economy, and the closure of small and inefficient plants, among other reasons. One effect of the reduction in SO2 emissions in China has been a reduction in acid deposition not only in China but also in Japan. Reductions should also improve visibility and reduce health problems. SO2 emission reductions may increase global warming, but this warming effect could be partially offset by reductions in the emissions of black carbon. How SO2 emissions in the region change in the coming decades will depend on many competing factors (economic growth, pollution control laws, etc.). However a continuation of current trends would result in sulfur emissions lower than any IPCC forecasts. PMID:12487289

  11. Measurements of Volatile Organic Compounds and Gaseous Sulfuric Acid During the 2008 CAREBEIJING Campaign

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Zheng, J.; Hu, M.; Zhu, T.

    2009-05-01

    Air quality in Beijing has been a hot topic recently, because Beijing hosted the 2008 summer Olympics. To combat the problem, China ordered numerous factories shut down or used only sporadically during the games to limit air pollution in the area. Another major step involved ordering about one-half of the city's 3.3 million vehicles off the road during the games, allowing only cars on roads with odd or even-numbered license plates on alternate days until the games were over. In addition, China has implemented new auto emission standards since March 2009 with regulations that are similar to those used throughout Europe. Our team at the Texas A&M participated in the 2008 CAREBEIJING campaign, with the objectives of studying the complex chemistry of the air in Beijing, looking at emission controls and their effectiveness, studying the surrounding air from other regions and how it can affect Beijing's air, and comparing all of our findings with air quality in other cities we have examined, such as Mexico City and Houston. In this talk, preliminary results of measurements of volatile organic compounds (VOCs) and gaseous sulfuric acid will be presented to discuss the trends of VOCs and new particle formation associated with the traffic control.

  12. Dynamic Rheological Studies of Poly(p-phenyleneterephthalamide) and Carbon Nanotube Blends in Sulfuric Acid

    PubMed Central

    Cao, Yutong; Liu, Zhaofeng; Gao, Xianghua; Yu, Junrong; Hu, Zuming; Liang, Ziqi

    2010-01-01

    We have studied the dynamic scanning of liquid-crystalline (LC) poly(p-phenyleneterephthalamide) sulfuric acid (PPTA-H2SO4) solution, and its blend with single-walled carbon nanotubes (SWNTs), by using a flat plate rotational rheometer. The effects of weight concentration and molecular weight of PPTA, as well as operating temperature, on dynamic viscoelasticity of the PPTA-H2SO4 LC solution system are discussed. The transition from a biphasic system to a single-phase LC occurs in the weight concentration range of SWNTs from 0.1% to 0.2%, in which complex viscosity reaches the maximum at 0.2 wt% and the minimum at 0.1 wt%, respectively, of SWNTs. With increasing SWNT weight concentration, the endothermic peak temperature increases from 73.6 to 79.9 °C. The PPTA/SWNT/H2SO4 solution is in its plateau zone and storage modulus (G?) is a dominant factor within the frequency (?) range of 0.1–10 rad/s. As ? increases, the G? rises slightly, in direct proportion to the ?. The loss modulus (G?) does not rise as a function of ? when ? < 1 s?1, then when ? > 1 s?1 G? increases faster than G?, yet not in any proportion to the ?. PMID:20480024

  13. Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kürten, A.; Rondo, L.; Ehrhart, S.; Curtius, J.

    2011-03-01

    The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3- ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (americium-241) ion source which has been used previously. The results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of 1 min it is ~6 × 104 molecule cm-3 of H2SO4. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.

  14. Effects of impurities in sulfuric acid on the corrosion resistance of zirconium

    SciTech Connect

    Yau, T.L.

    1982-09-01

    Zirconium is one of the few metals that resists attack by sulfuric acid (H/sub 2/SO/sub 4/) up to 75% concentration. It is being frequently used to handle the acid in the difficult concentration range of 40 to 60%. However, due to environmental concerns, the dumping and the storage of H/sub 2/SO/sub 4/ wastes have become a problem. Contaminated H/sub 2/SO/sub 4/ is involved in many processes. The purpose of this investigation is a more precise characterization on the effects of impurities on the corrosion resistance of zirconium. Corrosion behavior of zirconium alloys in H/sub 2/SO/sub 4/ with common detrimental impurities, that is, Fe/sup +3/, Cu/sup +2/, Cl/sup -/, NO/sup -//sub 3/, and seawater, has been investigated. It has been found that Zr 702 and Zr 704 can tolerate a larger amount of impurities than Zr 705. Welds of zirconium alloys are susceptible to local corrosion in contaminated H/sub 2/SO/sub 4/. However, the local corrosion of welds can be easily avoided by a proper heat treatment. For our corrosion tests, the heat treatment was performed at 760/sup 0/C for 15 min. The performance of passivated Zr 702 and Zr 705 under a simulated upset condition, for example boiling 74% H/sub 2/SO/sub 4/, has been studied. It has been found that Zr 702 can withstand the upset conditions without significant attack up to 20 min, but Zr 705 will corrode immediately and rapidly.

  15. A Density Functional Theory Study of Temperature Dependence of Cluster Formation from Sulfuric Acid and Ammonia

    NASA Astrophysics Data System (ADS)

    lin, H.; Chon, N. L.; Lee, S.

    2013-12-01

    Recent atmospheric nucleation studies have shown that acid-base reactions are essential at the initial step of aerosol nucleation. Ammonia is the most abundant base compound present in the atmosphere. Ammonia can directly interact with sulfuric acid clusters to reduce Gibbs free energy of cluster formation and growth, but the role that ammonia plays in atmospheric nucleation is still not well understood, especially at the molecular cluster level. We have performed density functional theory (BL3YP) and ab initio (MP2) calculations to study energetics of cluster formation for (NH3)m(H2SO4) and (NH3)(H2SO4)n (m, n = 1-6) in the temperature range from 200-300 K. For the model (NH3)m(H2SO4) clusters, bindings were predicted to increase from m = 1 to 6 at 200 K, while the most stable complex at 300 K was found to be at m = 2. For the (NH3)(H2SO4)n complexes, enthalpic contributions dominated and the binding is more stable for larger n. The temperature dependency has stronger effects on the (NH3)m(H2SO4) complexes, among which the lowest free energy shifts from m = 6 at T = 200 K to m = 5 around T = 240 K and further to m = 2 at T ? 280 K. The effects on the (NH3)(H2SO4)n complexes are much smaller, while there are similar trends that favor larger n for all temperatures between 200 and 300 K. These results thus indicate that the role of ammonia in atmospheric aerosol nucleation is critical in a wide range of atmospheric temperature conditions.

  16. Hydration of the sulfuric acid-methylamine complex and implications for aerosol formation.

    PubMed

    Bustos, Danielle J; Temelso, Berhane; Shields, George C

    2014-09-01

    The binary H2SO4-H2O nucleation is one of the most important pathways by which aerosols form in the atmosphere, and the presence of ternary species like amines increases aerosol formation rates. In this study, we focus on the hydration of a ternary system of sulfuric acid (H2SO4), methylamine (NH2CH3), and up to six waters to evaluate its implications for aerosol formation. By combining molecular dynamics (MD) sampling with high-level ab initio calculations, we determine the thermodynamics of forming H2SO4(NH2CH3)(H2O)n, where n = 0-6. Because it is a strong acid-base system, H2SO4-NH2CH3 quickly forms a tightly bound HSO4(-)-NH3CH3(+) complex that condenses water more readily than H2SO4 alone. The electronic binding energy of H2SO4-NH2CH3 is -21.8 kcal mol(-1) compared with -16.8 kcal mol(-1) for H2SO4-NH3 and -12.8 kcal mol(-1) for H2SO4-H2O. Adding one to two water molecules to the H2SO4-NH2CH3 complex is more favorable than adding to H2SO4 alone, yet there is no systematic difference for n ? 3. However, the average number of water molecules around H2SO4-NH2CH3 is consistently higher than that of H2SO4, and it is fairly independent of temperature and relative humidity. PMID:24730699

  17. Separation of thorium(IV) and extracting rare earths from sulfuric and phosphoric acid solutions by solvent extraction method

    Microsoft Academic Search

    Deqian Li; Yong Zuo; Shulan Meng

    2004-01-01

    The bastnasite of Baotou (China) was roasted in concentrated sulfuric acid at 250–300°C and the calcined products were leached by water. Almost all rare earths (RE) were moved into solutions in trivalent along with some radioactive impurity thorium(IV) (Th(IV))which accounts for 0.4% of RE and other impurities such as Fe(III), Ca, F, P, etc. Through fractional extraction (seven stages for

  18. Cation exchange membranes based on grafted PS\\/DVB–ETFE films: An investigation of their electrochemical characteristics in sulfuric acid

    Microsoft Academic Search

    Le Xuan Tuan; Boulehdid Hanae; Mérida Vargas Lara; Claudine Buess-Herman

    2009-01-01

    The electrochemical characteristics of lab-made cation exchange membranes based on a PS\\/DVB–ETFE film with different degrees of grafting (37% and 44%, respectively) have been evaluated in presence of sulfuric acid by means of current–voltage, chronopotentiometric and conductivity measurements. The transport number of the hydrogen ion in the membranes is estimated by resorting to the Sand equation. The chronopotentiometric curves of

  19. Effects of four types of dilute acid washing on moso bamboo pyrolysis using Py-GC/MS.

    PubMed

    Dong, Qing; Zhang, Shuping; Zhang, Li; Ding, Kuan; Xiong, Yuanquan

    2015-06-01

    The influences of four types of dilute acid washing (H2SO4, HCl, HF, HNO3) on moso bamboo pyrolysis were investigated via pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The effects of acid washings on the inorganics contents and the chemical structure were also analyzed. The results indicated that all the acid washings could effectively remove a large portion of inorganics and disrupt the chemical structure to a certain extent. HCl-washing behaved the best in removing inorganics and had the most marked disruption effect on bamboo structure. Acid washings promoted the bamboo pyrolysis and increased the contents of both phenols and sugars. HCl-washing had the most significant promotion effect on the levoglucosan formation with the absolute peak area increasing from 8.12×10(8) to 1.92×10(9). The absolute peak areas of 2,3-dihydrobenzofuran decreased more or less after acid washings. All the acid washings except H2SO4-washing could significantly increase the absolute peak area of methoxyeugenol. PMID:25755014

  20. Sulfuric acid vapor in the atmosphere of Venus as observed by the Venus Express Radio Science experiment VeRa

    NASA Astrophysics Data System (ADS)

    Oschlisniok, Janusz; Pätzold, Martin; Häusler, Bernd; Tellmann, Silvia; Bird, Mike; Andert, Thomas; Remus, Stefan

    2015-04-01

    The cloud deck within Venus' atmosphere, which covers the entire planet between approx. 50 and 70 km altitude, consists mostly of liquid and gaseous sulfuric acid. The gaseous part increases strongly just below the main clouds and builds an approx. 15 km thick haze layer of H2SO4. This region is responsible for a strong absorption of radio waves as seen in VeRa radio science observations. The absorption of the radio signals during occultations is used to derive the abundance of gaseous sulfuric acid. VeRa probes the atmosphere of Venus since 2006 with radio signals at 13 cm (s-band) and 3.6 cm (x-band) wavelengths. The collection of nine years of radio science data provides a picture of the global distribution of the sulfuric acid vapor distribution within Venus' atmosphere. We present H2SO4 profiles retrieved with VeRa and compare those with H2SO4 profiles observed by previous missions.

  1. The chemical processing of gas-phase carbonyl compounds by sulfuric acid aerosols: 2,4-pentanedione

    NASA Astrophysics Data System (ADS)

    Nozičre, Barbara; Riemer, Daniel D.

    This work investigates the interactions between gas-phase carbonyl compounds and sulfuric acid aerosols. It focuses on understanding the chemical processes, giving a first estimate of their importance in the atmosphere, and suggesting directions for further investigations. The solubility and reactivity of a compound with a large enolization constant, 2,4-pentanedione, in water/sulfuric acid solutions 0-96 wt% have been investigated at room temperature using the bubble column/GC-FID technique. 2,4-pentanedione was found to undergo aldol condensation at acidities as low as 20 wt% H 2SO 4, that is, well in the tropospheric range of aerosol composition. In agreement with well-established organic chemical knowledge, this reaction resulted in changes of color of the solutions of potential importance for the optical properties of the aerosols. 2,4-pentanedione was also found to undergo retroaldol reaction, specific to dicarbonyl compounds, producing acetone and acetaldehyde. The Henry's law coefficient for 2,4-pentanedione was found to be a factor 5 larger than the one of acetone over the whole range of acidity, with a value in water of H (297 K)=(155±27) M atm -1. A chemical system is proposed to describe the transformations of carbonyl compounds in sulfuric acid aerosols. Aldol condensation is likely to be the most common reaction for these compounds, probably involving a large number of the ones present in the atmosphere and a wide range of aerosol compositions. The enolization constant contributes as a proportional factor to the rate constant for aldol condensation, and is shown in this work to contribute as an additive constant to the Henry's law coefficient. In addition to the many important aspects of these reactions illustrated in this work, the rate of aldol condensation was estimated to be potentially fast enough for the losses of some compounds in acidic aerosols to compete with their gas-phase chemistry in the atmosphere.

  2. Parameterization for Atmospheric New-Particle Formation: Application to a System Involving Sulfuric Acid and Condensable Water-Soluble Organic Vapors

    Microsoft Academic Search

    Veli-Matti Kerminen; Tatu Anttila; Kari Lehtinen; Markku Kulmala

    2004-01-01

    A new parameterization for atmospheric new-particle formation has been developed. The parameterization takes into account the early growth of nucleated clusters by condensation of sulfuric acid and water-soluble organic vapors, as well as the scavenging of the growing nuclei by coagulation into larger pre-existing particles. The main input parameters are the nucleation rate, the concentration of sulfuric acid and organic

  3. Synergistic effect between 4-(2-pyridylazo) resorcin and chloride ion on the corrosion of cold rolled steel in 0.5 M sulfuric acid

    Microsoft Academic Search

    Libin Tang; Xueming Li; Guannan Mu; Lin Li; Guangheng Liu

    2006-01-01

    The corrosion inhibition of 1-(2-pyridylazo)-2-naphthol (PAR) on the corrosion of cold rolled steel in 0.5M sulfuric acid (H2SO4) was studied using weight loss method and potentiodynamic polarization method. Results obtained revealed that together with chloride ion, PAR is an effective corrosion inhibitor for steel corrosion in sulfuric acid. It was found that for steel corrosion inhibition in the presence of

  4. The synergistic inhibition of the cold rolled steel Corrosion in 0.5 M sulfuric acid by the mixture of OP and bromide ion

    Microsoft Academic Search

    Xueming Li; Libin Tang; Guannan Mu; Lin Li; Guangheng Liu

    2007-01-01

    The synergistic inhibitive effect of the mixture of OP and NaBr on the corrosion of cold rolled steel in 0.5 M sulfuric acid has been investigated using weight loss and polarization method. The results reveal that corrosion of cold rolled steel has been efficiently inhibited by OP in the presence of NaBr in sulfuric acid, and inhibition efficiency increases with increasing

  5. Thermodynamic properties of 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole as a corrosion inhibitor for mild steel in normal sulfuric acid medium

    Microsoft Academic Search

    M. Bouklah; B. Hammouti; M. Lagrenée; F. Bentiss

    2006-01-01

    The corrosion rates in the presence of 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole (4-MOX) as a steel corrosion inhibitor in 0.5M sulfuric acid, were measured by the weight loss method, in the range of temperatures from 303 to 343K. Results obtained revealed that 4-MOX performed excellently as a corrosion inhibitor for mild steel in sulfuric acid media and its efficiency attains more than 96.19% at

  6. The impacts of pretreatment on the fermentability of pretreated lignocellulosic biomass: a comparative evaluation between ammonia fiber expansion and dilute acid pretreatment

    Microsoft Academic Search

    Ming W Lau; Christa Gunawan; Bruce E Dale

    2009-01-01

    BACKGROUND: Pretreatment chemistry is of central importance due to its impacts on cellulosic biomass processing and biofuels conversion. Ammonia fiber expansion (AFEX) and dilute acid are two promising pretreatments using alkaline and acidic pH that have distinctive differences in pretreatment chemistries. RESULTS: Comparative evaluation on these two pretreatments reveal that (i) AFEX-pretreated corn stover is significantly more fermentable with respect

  7. Fatigue Crack Nucleation Studies on Sulfuric Acid Anodized 7075-T73 Aluminum

    NASA Astrophysics Data System (ADS)

    Savas, Terence P.; Earthman, James C.

    2014-06-01

    The influence of a sulfuric acid anodic coating process on the fatigue crack nucleation behavior of 7075-T73 aluminum alloy was investigated. Silicone surface replication in combination with carbon sputter coating and scanning electron microscopy (SEM) allowed for in situ monitoring of the number of cycles for crack nucleation. A single edge circular notch (SECN) coupon was designed for the present study to localize fatigue damage thus enhancing fatigue crack detection and capture the effects of multiaxial stress conditions indicative of a majority engineering applications. Linear elastic finite element modeling of the SECN coupon was performed to quantify the von Mises equivalent stress distribution and the stress concentration factor of the notched region. The experimental results indicate that the presence of localized pitting corrosion initiated during the anodic coating pretreatment process had an adverse effect on fatigue performance. Specifically, multiple crack nucleation sites were evident as opposed to a single crack origin for the untreated specimens. Post-cycling SEM surface examinations displayed networks of micro-cracks in the anodic coating emanating from the pits although these were not found to be fatigue crack origin sites during post SEM fractographic exams. Thus, the stress concentration effect of the corrosion pits was found to be predominant. The total cycles to failure on average was reduced by approximately 60% for the anodic coated versus untreated specimens. A strategy is also discussed on how to mitigate accelerated crack nucleation by controlled surface pretreatment and use of a chromated chemical conversion coating in lieu of an anodic coating for selective applications.

  8. Dietary Sulfur Amino Acid Effects on Fasting Plasma Cysteine/Cystine Redox Potential in Humans

    PubMed Central

    Jones, Dean P.; Park, Youngja; Gletsu-Miller, Nana; Liang, Yongliang; Yu, Tianwei; Accardi, Carolyn Jonas; Ziegler, Thomas R.

    2010-01-01

    Objective Oxidation of plasma cysteine/cystine (Cys/CySS) redox potential (EhCySS) has been associated with risk factors for cardiovascular disease in humans. Cys and CySS are derived from dietary sulfur amino acids (SAA), but the specific effects of SAA depletion and repletion on Cys/CySS redox indices are unknown. The present study examined the effect of dietary SAA intake level on free Cys, free CySS and EhCySS in human plasma under fasting conditions. Research Methods and Procedures Healthy individuals aged 18–36 y (n=13) were equilibrated to foods providing the RDA for SAA and then fed chemically defined diets without SAA (0 mg·kg?1·d?1; n=13) followed by SAA at levels approximating the mean (56 mg·kg?1·d?1; n=8) or 99th percentile (117 mg·kg?1·d?1; n=5) intake levels of Americans. Fasting plasma samples were collected daily during 4-d study periods and analyzed for free Cys, free CySS and the EhCySS. Results The SAA-free diet significantly (p<0.05) decreased plasma free Cys concentrations and oxidized EhCySS values after 4 days of SAA depletion. With SAA repletion at 56 mg·kg?1·d? 1, plasma free Cys increased significantly and values for EhCySS became more reducing. Administration of a diet providing a higher dose of SAA (117 mg·kg?1·d?1) resulted in a significantly higher level of free Cys and a more reducing EhCySS. Conclusions These results show that free Cys and Cys/CySS redox potential (EhCySS) in fasting plasma are affected by dietary SAA intake level in humans. Significant changes occur slowly over 4 days with insufficient SAA intake, but rapidly (after 1 day) with repletion. PMID:20471805

  9. Effects of dietary sulfur amino acids on lead toxicity in chicks

    SciTech Connect

    Latta, D.M.

    1986-01-01

    Factorial experiments were conducted to examine the interactions of dietary methionine with cystine, choline and glycine in lead (Pb) intoxicated chicks. In Experiment 1, chicks were fed a basal diet deficient in methionine and total sulfur-containing amino acids (SAA) with 0 or 1000 ppm added Pb. Methionine or methionine plus cystine improved growth regardless of Pb level; cystine addition alone improved growth only when Pb was present. Dietary methionine appeared to counteract Pb toxicity more effectively than cystine. In Experiments 2 and 3 dietary variables were 0 or 1000 ppm Pb, adequate or inadequate methionine and marginal or excess (Experiment 2) or adequate or inadequate (Experiment 3) choline. In Experiment 2 growth depression by Pb was less with methionine-adequate compared to methionine-inadequate diets; there were no differences in growth with choline-marginal or choline-excess diets. In Experiment 3, the Pb-induced growth depression was exacerbated by adequate choline when methionine-inadequate diets were fed. It appears that Pb lowers the chick's choline requirement and that the methyl moiety of methionine does not participate directly in Pb detoxification. In Experiment 4 effects of adequate or deficient methionine, adequate or excess glycine and 0 or 1000 ppm Pb in choline-deficient chicks were studied. Methionine stimulated growth and the response was greater when excess glycine was present. Excess glycine stimulated growth only in the presence of adequate methionine suggesting glycine is limiting for growth in choline-deficient, methionine-adequate diets. These studies indicate that adequate methionine ameliorates Pb-induced growth depression in growing chicks but that the methionine effect is greater with choline-adequate than with choline-deficient diets. The amelioration of Pb toxicity by methionine may be partly related to increased excretion of Pb.

  10. Soluble sulfur species extracted from coal by chemical leaching. [MS thesis; mineral and coal-derived pyrite; 114 references

    SciTech Connect

    Stephenson, M.D.

    1982-07-01

    The nature of the soluble sulfur-containing reaction products from the desulfurization of pyrite was studied. The rate of oxydesulfurization of the two varieties of pyrite was studied under the leaching conditions of the Ames process. Concentrations of soluble sulfur species were determined for oxydesulfurization using leach solutions of sodium carbonate, sodium bicarbonate, distilled water, and dilute sulfuric acid and for alkaline leaching without oxygen using sodium carbonate. Mineral grade pyrite was found to be much less reactive towards oxydesulfurization than coal-derived pyrite, although the mechanism of sulfur removal was apparently the same. The sulfur containing products of oxydesulfurization were found to be thiosulfate, sulfite, and sulfate for alkaline leach solutions, and elemental sulfur and sulfuric acid when neutral or acidic solutions were used. For the Ames process, thiosulfate was usually the major sulfur containing product, although oxidation to sulfite and sulfate was found to take place. Oxidation of thiosulfate did not occur with oxygen alone, but did occur in the presence of oxygen and partially reacted pyrite. Higher temperatures and higher oxygen partial pressures favored formation of sulfate at the expense of both thiosulfate and sulfite. With neutral and acidic leach solutions, sulfuric acid accounted for most of the sulfur, although measurable quantities of elemental sulfur were present.Higher oxygen partial pressures and higher temperatures favored the formation of sulfuric acid at the expense of elemental sulfur. Pyrite oxidized faster under alkaline conditions than under neutral or acidic conditions. Pyrite was also leached at high temperatures in a sodium carbonate solution in the absence of oxygen.

  11. Comparison of isotope dilution and excretion methods for determining the half-life of ascorbic acid in the guinea pig

    SciTech Connect

    Kipp, D.E.; Rivers, J.M.

    1984-08-01

    The half-life of ascorbic acid (AA) in guinea pigs was investigated by the isotope dilution and excretion methods. The dilution method measures (1-14C)AA disappearance from the plasma, whereas the excretion method measures the elimination of (1-14C)AA and the metabolites from the body. Two groups of animals underwent both isotope studies in reverse order. Animals were conditioned to the experimental procedures and fed 2.5 mg AA/100 g body weight orally to maintain a daily intake of the vitamin independent of food consumption. The two isotope procedures imposed similar stress on the animals, as determined by plasma cortisol levels and body weight changes. The AA half-life calculations of the rapidly exchangeable pool by the isotope dilution method yielded values of 1.23 and 0.34 hours for the two groups, respectively. The half-life of the slowly exchangeable pool for the two groups was 60.2 and 65.8 hours, respectively. The half-life of AA in the rapidly exchangeable pool, as measured by the excretion studies, was 4.57-8.75 hours. For the slowly exchangeable pool, it was 146-149 hours. The longer half-life of both pools obtained with the excretion method indicates that the isotope is disappearing from the plasma more rapidly than it is being excreted. This suggests that a portion of the (1-14C)AA leaving the plasma is removed to a body pool that is not sampled by the isotope excretion method.

  12. Mössbauer study of the inorganic sulfur removal from coals

    NASA Astrophysics Data System (ADS)

    Reyes Caballero, F.; Martķnez Ovalle, S. A.

    2014-01-01

    Mössbauer Spectroscopy (MS) was applied to study the occurrence and behavior of the iron-sulfur-containing minerals in coal and coal fractions obtained by different separation methods: hydrocyclonic, flotation and chemical removal process. Samples of one high sulfur coal from Guachinte mine (Valle, Colombia) and three low sulfur coals from the El Salitre zone (Paipa-Boyacį, Colombia) were analyzed. MS evidenced only the presence of pyrite in Esmeralda and Las Casitas coals, while it identified pyrite and siderite on Cerezo coal. MS and SEM- EDX confirm the inorganic sulfur removal on Guachinte coal submitted to hydrocyclonic removal process. MS of the precipitated coal fraction from Las Casitas mine obtained by flotation in water showed the presence of ferrous sulfate because of coal-weathering process. Treatment with hot diluted HNO3 equal to 27 acid on raw coal sample from Las Casitas mine showed that almost all of the pyrite in raw coal was removed.

  13. Ferredoxins from the photosynthetic purple non-sulfur bacterium Rhodopseudomonas palustris. Isolation and amino acid sequence of ferredoxin I.

    PubMed

    Minami, Y; Wakabayashi, S; Yamada, F; Wada, K; Zumft, W G; Matsubara, H

    1984-09-01

    Two ferredoxins, ferredoxins I and II, were prepared from Rhodopseudomonas palustris. They were separated on a Sephadex column after carboxymethylation and ferredoxin I, the major component, was subjected to an amino acid sequence study. The protein was composed of 63 amino acid residues and the sequence was as follows: (sequence; see text). The molecular weight was calculated to be 6,718, excluding iron and sulfur atoms. The distribution of the nine cysteine residues was similar to but clearly distinct from those of ferredoxins of other photosynthetic bacteria. Comparison of this ferredoxin with those of other bacteria suggests that the photosynthetic bacteria evolved on separate lines. Ferredoxin II was also subjected to analyses of amino acid composition and terminal sequences, but no further study was possible due to the limited material. Although the composition was different from that of ferredoxin I, the terminal sequences were exactly the same as those of ferredoxin I. PMID:6389527

  14. New method of treating dilute mineral acids using magnesium–aluminum oxide

    Microsoft Academic Search

    Tomohito Kameda; Fumiko Yabuuchi; Toshiaki Yoshioka; Miho Uchida; Akitsugu Okuwaki

    2003-01-01

    Mineral acids, such as H3PO4, H2SO4, HCl, and HNO3, were treated with magnesium–aluminum oxide (Mg–Al oxide), which behaved as a neutralizer and fixative of anions. Anion removal increased with increasing Mg–Al oxide quantity, time, Mg\\/Al molar ratio, and initial acid concentration. Up to 95% removal of anions was achieved in 0.5N acids using a stoichiometric quantity of Mg0.80Al0.20O1.10 for H3PO4,

  15. Stratospheric Sulfuric Acid and Black Carbon Aerosol Measured During POLARIS and its Role in Ozone Chemistry

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Pueschel, R. F.; Drdla, K.; Verma, S.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosol can affect the environment in three ways. Sulfuric acid aerosol have been shown to act as sites for the reduction of reactive nitrogen and chlorine and as condensation sites to form Polar Stratospheric Clouds, under very cold conditions, which facilitate ozone depletion. Recently, modeling studies have suggested a link between BCA (Black Carbon Aerosol) and ozone chemistry. These studies suggest that HNO3, NO2, and O3 may be reduced heterogeneously on BCA particles. The ozone reaction converts ozone to oxygen molecules, while HNO3 and NO2 react to form NOx. Finally, a buildup of BCA could reduce the single-scatter albedo of aerosol below a value of 0.98, a critical value that has been postulated to change the effect of stratospheric aerosol from cooling to warming. Correlations between measured BCA amounts and aircraft usage have been reported. Attempts to link BCA to ozone chemistry and other stratospheric processes have been hindered by questions concerning the amount of BCA that exists in the stratosphere, the magnitude of reaction probabilities, and the scarcity of BCA measurements. The Ames Wire Impactors (AWI) participated in POLARIS as part of the complement of experiments on the NASA ER-2. One of our main objectives was to determine the amount of aerosol surface area, particularly BCA, available for reaction with stratospheric constituents and assess if possible, the importance of these reactions. The AWI collects aerosol and BCA particles on thin Palladium wires that are exposed to the ambient air in a controlled manner. The samples are returned to the laboratory for subsequent analysis. The product of the AWI analysis is the size, surface area, and volume distributions, morphology and elemental composition of aerosol and BCA. This paper presents results from our experiments during POLARIS and puts these measurements in the context of POLARIS and other missions in which we have participated. It describes modifications to the AWI data analysis procedures in which the collection of BCA is modeled as a fractal aggregate. The new analysis results in an increase in BCA surface area of approximately 24 and an increase in mass of 7-10 from the previous method. For the current study, BCA surface area is used in computer models that attempt to predict measured NOx/NOy ratios and O3 depletion rates. Inclusion of the HNO3 reaction with BCA in one model tends to improve the agreement of calculated to measured NOx/NOy ratio. However, it was found that these trends are viable only if the reactions are catalytic.

  16. A Procedure for the Fractionation of Aqueous Aluminum in Dilute Acidic Waters

    Microsoft Academic Search

    Charles T. Driscoll

    1984-01-01

    A procedure was developed for the fractionation of aqueous aluminum. This procedure results in the determination of acid-soluble aluminum, non-labile monomeric aluminum and labile monomeric aluminum. Acid-soluble aluminum is thought to include colloidal aluminum and extremely non-labile organic complexes. Non-labile monomeric aluminum is thought to include monomeric alumino-organic complexes. Labile monomeric is comprised of aquo aluminum as well as inorganic

  17. Dissolution of mechanically activated Panzhihua ilmenites in dilute solutions of sulphuric acid

    Microsoft Academic Search

    Chun Li; Bin Liang; Ling-hong Guo

    2007-01-01

    Dissolution of mechanically activated Panzhihua ilmenite was conducted in 5–20% sulphuric acid solutions. With high milling intensity the milling atmosphere significantly affected the dissolution with milling under vacuum almost double the dissolution of ilmenite milled in air. This was due to formation of a lot of acid-resistant pseudorutile and lowering level of the lattice strains, especially in the c-axis direction

  18. Synergistic extraction of rare earths by mixture of HDEHP and HEH\\/EHP in sulfuric acid medium

    Microsoft Academic Search

    Yongqi ZHANG; Jianning LI; Xiaowei HUANG; Chunmei WANG; Zhaowu ZHU; Guocheng ZHANG

    2008-01-01

    The extraction of RE(III) (RE=La, Nd, Sm, Gd) in sulfuric acid medium using the mixture of HDEHP(H2B2) and HEH\\/EHP(H2L2) was investigated. The synergistic enhancement coefficient(R) was calculated for La (1.96), Nd(3.52), Sm(5.96), and Gd(5.71), respectively, at pH=2.0, and it was seen that the R increased with the increase of aqueous quilibrium pH. The configuration of the extracted complexes was considered

  19. Characterization of acid rain for source identification. Task I. Sulfur isotope ratioing. Final report

    SciTech Connect

    Not Available

    1983-01-01

    During FY 1983, work proceeded towards the goal of refining a thermal ionization mass spectrometric procedure for the determination of sulfur isotopic ratios. The long range goal of this work is to measure the differences in the /sup 32/S//sup 34/S ratios in natural samples in order to identify sources of sulfur impacting on receptor sites. A portion of this effort was spent in evaluating the precision of the technique. At the present time, the /sup 32/S//sup 34/S ratio in a sample of 50 ..mu..g can be measured with a precision of 0.1% (1S) or better. However, the reproducibility between samples is about a factor of two poorer. The new thermal ionization technique for the determination of sulfur isotopic ratios has been applied to the measurement of natural samples. To test the idea that variations in /sup 32/S//sup 34/S ratios could be detected and would place valuable constraints on sulfur sources and atmospheric processes, a suite of samples were analyzed from the DOE - High Altitude Sampling Program (HASP). The HASP program consists of Project Airstream and Project Ashcan. More than 30 samples from Project Airstream have been measured. These samples range in size from 15 ..mu..g to 300 ..mu..g and were the first determinations of /sup 32/S//sup 34/S ratios on stratospheric samples from this program. The delta /sup 34/S values have been plotted. With these limited data it is not possible to make definitive interpretations, but the following observation can be made: (1) the observed range is delta/sup 34/S values is from -35 to +32. This range almost covers the total range commonly observed in terrestrial systems; (2) El Chichon injected sulfur into the stratosphere with delta/sup 34/S value near zero in April 1982. There are clearly multiple sources of sulfur or large changes in the /sup 32/S//sup 34/S ratios are being produced as SO/sub 2/ conversion to SO/sub 4//sup -2/ proceeds; and (3) sulfur isotopic data can be used to constrain interpretations of sulfur concentration data. 7 figures, 7 tables.

  20. An acid-stable Zn(II) complex: electrodeposition in sulfuric acid and the effect on the zinc-lead dioxide battery.

    PubMed

    Zhang, Miao Miao; Gong, Yun; Zhang, Pan; Shi, Hui Fang; Lin, Jian Hua

    2014-12-01

    An acid-stable Zn(II) complex formulated as Zn2(HL)2(SO4)·H2O (1) and an acid-unstable complex formulated as Zn2L2·12H2O (2) were hydro(solvo)thermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 features a uninodal 6-connected 2-fold interpenetrating three-dimensional (3D) dense architecture with {4(12)·6(3)}-pcu topology, and complex 2 exhibits a 2-nodal (3, 6)-connected 3D open architecture with (4·6(2))2(4(2)·6(10)·8(3))-rtl topology. The results indicate that the stability of complex 1 in sulfuric acid is probably associated with the coordinated SO4(2-) in the quite dense structure, and complex 1 can also be synthesized via electrodeposition in sulfuric acid; it can improve the discharging characteristics of the zinc-lead dioxide battery at room temperature. PMID:25312385

  1. ADVANCED SULFUR CONTROL CONCEPTS

    SciTech Connect

    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).

  2. Extraction of hydrochloric acid from dilute solutions by the use of organic solvents

    E-print Network

    Pandya, Harishkumar Chandulal

    1967-01-01

    column at 30 C. Thus, only acid and water form the re- flux. However, the reflux could have been separated at 60 C, but because equilibrium data for high concentra- tions at this temperature were not available, it was assumed otherwise (Fig. 2... to form a substance preferen- tially soluble in the solvent, or insoluble in both liquid phases. The acid-solvent systems investigated in this work are similar in many respects to the amine-water systems used in solvent extraction desalination (24...

  3. Sulfuric acid doped poly diaminopyridine/graphene composite to remove high concentration of toxic Cr(VI).

    PubMed

    Dinda, Diptiman; Kumar Saha, Shyamal

    2015-06-30

    Sulfuric acid doped diaminopyridine polymers are synthesized in situ on graphene oxide surface via mutual oxidation-reduction technique. Exploiting large and highly porous surface, we have used this polymer composite as an adsorbent to remove high concentration of toxic Cr(VI) from water. It shows very high adsorption capacity (609.76 mg g(-1)) during removal process. The composite takes only 100 min to remove high concentration of 500 mg L(-1) Cr(VI) from water. Interesting features for this material is the enhancement of removal efficiency at lower acidic condition due to the formation of acid doped emeraldine salt during polymerization. XPS and AAS measurements reveal that our prepared material mainly follows reduction mechanism at higher acidic condition while anions exchange mechanism at lower acidic condition during the removal experiments. Good recycling ability with ? 92% removal efficiency after fifth cycle is also noticed for this material. Easy preparation, superior stability in acidic condition, remarkable removal efficiency and excellent recycling ability make this polymer composite an efficient material for modern filtration units in waste water purification. PMID:25771215

  4. Advanced Control Technology Development of Sulfuric Acid-Connecting System Based on Fuzzy Control

    Microsoft Academic Search

    Yan Dong; Qin Bin

    2010-01-01

    The theme of the paper is treatment of discharges of sulfur dioxide from process of petrochemical, aiming at the problems of the long time, none linearity and the precise mathematic that is hard to build, we consider combining the advanced fuzzy control with the traditional automation technology to achieve low cost automatization. According to the principles of fuzzy control and

  5. Alternatives for detoxification of diluted-acid lignocellulosic hydrolyzates for use in fermentative processes: a review

    Microsoft Academic Search

    Solange Inźs Mussatto; Inźs Conceiēćo Roberto

    2004-01-01

    Acid hydrolysis of lignocellulosic materials produces several inhibitory compounds, such as sugar and lignin degradation products, compounds derived from the lignocellulosic structure, and heavy metal ions. Their toxicity is a major factor limiting bioconversion processes that utilize hydrolyzates. The identification of these compounds and the choice of the best hydrolyzate detoxification method are important for improving the efficiency of the

  6. Chemical structures of corn stover and its residue after dilute acid prehydrolysis and enzymatic hydrolysis: Insight into factors limiting enzymatic hydrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Advanced solid-state NMR techniques and wet chemical analyses were applied to investigate untreated corn stover (UCS) and its residues after dilute acid prehydrolysis (DAP) and enzymatic hydrolysis (RES) to provide evidence for the limitations to the effectiveness of enzyme hydrolysis. Advanced soli...

  7. Determination of volatile elements in biological materials by isotopic dilution ETV-ICP-MS after dissolution with tetramethylammonium hydroxide or acid digestion

    Microsoft Academic Search

    Dirce Pozebon; Valderi L. Dressler; Adilson J. Curtius

    2000-01-01

    Isotopic dilution for the determination of Ag, Cd, Hg, Pb and Tl in biological materials by ETV-ICP-MS is proposed. The sample was simply dissolved with tetramethylammonium hydroxide (TMAH) or acid digested in a microwave furnace, with an on line matrix separation. When the dissolution was employed, Ir was used as a chemical modifier for Hg and Pb and Pd was

  8. Application of a slurry feeder to 1 and 3 stage continuous simultaneous saccharification and fermentation of dilute acid pretreated corn stover

    E-print Network

    California at Riverside, University of

    and fermentation of dilute acid pretreated corn stover Simone Brethauer 1 , Michael H. Studer 1 , Charles E. Wyman fermentation system was set up. The performance of continuous SSF of pretreated corn stover was measured: Lignocellulosic biomass Ethanol Simultaneous saccharification and fermentation (SSF) Continuous fermentation

  9. Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol: Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover

    Microsoft Academic Search

    D. Humbird; R. Davis; L. Tao; C. Kinchin; D. Hsu; A. Aden; P. Schoen; J. Lukas; B. Olthof; M. Worley; D. Sexton; D. Dudgeon

    2011-01-01

    This report describes one potential biochemical ethanol conversion process, conceptually based upon core conversion and process integration research at NREL. The overarching process design converts corn stover to ethanol by dilute-acid pretreatment, enzymatic saccharification, and co-fermentation. Building on design reports published in 2002 and 1999, NREL, together with the subcontractor Harris Group Inc., performed a complete review of the process

  10. The influence of solid\\/liquid separation techniques on the sugar yield in two-step dilute acid hydrolysis of softwood followed by enzymatic hydrolysis

    Microsoft Academic Search

    Sanam Monavari; Mats Galbe; Guido Zacchi

    2009-01-01

    BACKGROUND: Two-step dilute acid hydrolysis of softwood, either as a stand-alone process or as pretreatment before enzymatic hydrolysis, is considered to result in higher sugar yields than one-step acid hydrolysis. However, this requires removal of the liquid between the two steps. In an industrial process, filtration and washing of the material between the two steps is difficult, as it should

  11. Kinetics and mechanism of S-nitrosothiol acid-catalyzed hydrolysis: sulfur activation promotes facile NO+ release.

    PubMed

    Moran, Ernesto E; Timerghazin, Qadir K; Kwong, Elizabeth; English, Ann M

    2011-03-31

    The denitrosation of three primary S-nitrosothiols (RSNO; S-nitrosocysteine, S-nitroso-N-acetylcysteine, and S-nitrosoglutathione) and two tertiary RSNOs (S-nitrosopenicillamine and S-nitroso-N-acetylpenicillamine) was investigated in 3.75 M H(2)SO(4) to probe the mechanism of acid-catalyzed RSNO hydrolysis and its dependence on RSNO structure. This reversible reaction was forced to proceed in the denitrosation direction by trapping the nitrosating agent with HN(3). The primary RSNOs exhibited hydrolysis k(obs) values of ?2 × 10(-4) s(-1), and the tertiary RSNO k(obs) values were an order of magnitude higher. Product analysis by HPLC revealed that the parent thiols (RSHs) were formed in 90-100% yield on 79-99% RSNO denitrosation. Possible hydrolysis mechanisms were studied computationally at the CBS-QB3 level using S-nitrosomethanethiol (MeSNO) as a model RSNO. Consideration of RSNOs as a combination of conventional R-S-N?O, zwitterionic R-S(+)?N-O(-), and RS(-)/NO(+) ion-pair resonance structures was key in understanding the mechanistic details of acid-catalyzed hydrolysis. Protonation of the S-nitroso oxygen or nitrogen activates the sulfur and nucleophilic attack by H(2)O at this atom leads to the formation of the sulfoxide-protonated N-hydroxysulfinamide, MeS(+)(OH)NHOH, with barriers of 19 and 29 kcal/mol, respectively. Proton loss and reprotonation at the nitrogen lead to secondary hydrolysis that produces the sulfinic acid MeS(?O)OH and NH(2)OH. Notably, no low-energy RSNO hydrolysis pathway for HNO release was found in the computational analysis. Protonation of the S-nitroso sulfur gives rise to NO(+) release with a low activation barrier (?H(double dagger)(calc) ? 6 kcal/mol) and the formation of MeSH in agreement with experiment. The experimental k(obs) can be expressed as K(a)k(1), where K(a) is the acid dissociation constant for protonation of the S-nitroso sulfur and k(1) the pseudo-first-order hydrolysis rate constant. Given the low ?H(double dagger)(calc) for denitrosation of the S-protonated isomer, the observed slow rates of acid-catalyzed RSNO hydrolysis must be controlled by the magnitude of K(a). The 10-fold higher K(a) calculated for Me(3)CS(H(+))NO (?10(-15)) compared to MeS(H(+))NO (10(-16)) is consistent with the order of magnitude larger k(obs) reported here for the tertiary vs primary RSNOs. PMID:21384833

  12. Luminescence features from conical bubble collapse in 1,2 propanediol and its perturbation adding sulfuric acid

    NASA Astrophysics Data System (ADS)

    Navarrete, M.; Sanchéz, C.; Godķnez, F. A.; Mejķa, E. V.; Villagrįn, M.

    2011-01-01

    A summary of experimental findings on the luminescence from bubble collapse, CBL, varying the gas inert bubble content, the driving pressure and perturbing the liquid piston with small quantities of sulfuric acid is presented. The temporal, spectral, and spatial characteristics of the luminescence regarding with dynamic features of collapse are also examinees. CBL was reproduced using Argon gas, and 1, 2-propanediol as liquid piston. In general, the pulse shape exhibits a large variety of profiles. The luminescence intensity was increased two-fold and the pulse width decreased almost to half when the liquid was disturbed with sulfuric acid. Spectrally, the Swan, CH and CN lines were observed at low volume of Ar gas and low driving pressure, lines of OH°, Na*, K* always appear superimposed on an underlying continuum background. De-excitation of sodium atom at 589 nm and two satellites diffuse bands at ~554 nm and ~620 nm from alkali -metal-argon exciplexes was observed in both systems under certain conditions. All these findings point towards several sources of light emission that are generated during the compression time line, resulting in temporally and spatially inhomogeneous pulse. A mechanism for explain the bright CBL is broached.

  13. Tropospheric chemistry of natural hydrocarbons, aldehydes, and peroxy radicals: Their connections to sulfuric acid production and climate effects

    SciTech Connect

    Gaffney, J.S.; Marley, N.A.

    1993-05-01

    Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly isoprene, focusing on their importance in the production of aldehydes and peroxy radicals, leading to increased levels of hydrogen over regional forests. Hydrogen peroxide can lead to the wet oxidation of sulfur dioxide to acidic sulfate in aerosols, fogs, and clouds. In turn, acidic sulfate can act to as a light scattering aerosol and a source of cloud condensation nuclei (CCN), potentially leading to global cooling. Aerosol sulfate and other dissolved organic and inorganic compounds can also play important roles as a greenhouse species in the lower troposphere.

  14. Integrated conversion of food waste diluted with sewage into volatile fatty acids through fermentation and electricity through a fuel cell.

    PubMed

    Pant, Deepak; Arslan, Doga; Van Bogaert, Gilbert; Gallego, Yolanda Alvarez; De Wever, Heleen; Diels, Ludo; Vanbroekhoven, Karolien

    2013-01-01

    In this study, domestic wastewater was given a second life as dilution medium for concentrated organic waste streams, in particular artificial food waste. A two-step continuous process with first volatile fatty acid (VFA)/hydrogen production and second electricity production in microbial fuel cells (MFCs) was employed. For primary treatment, bioreactors were optimized to produce hydrogen and VFAs. Hydrolysis of the solids and formation of fermentation products and hydrogen was monitored. In the second step, MFCs were operated batch-wise using the effluent rich in VFAs specifically acetic acid from the continuous reactor of the first step. The combined system was able to reduce the chemical oxygen demand load by 90%. The concentration of VFAs was also monitored regularly in the MFCs and showed a decreasing trend over time. Further, the anode potential changed from -500 to OmV vs. Ag/AgCl when the VFAs (especially acetate) were depleted in the system. On feeding the system again with the effluent, the anode potential recovered back to -500 mV vs. Ag/AgCl. Thus, the overall aim of converting chemical energy into electrical energy was achieved with a columbic efficiency of 46% generating 65.33 mA/m2 at a specific cell potential of 148 mV. PMID:24350447

  15. Isolation and separation of transplutonium elements from other actinides on ion exchange resins from aqueous and aqueous ethanol solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1987-11-01

    The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on an anion exchange resin and a cation exchange resin in aqueous and aqueous alcohol solutions of sulfuric acid was investigated as a function of the concentration of various components of the solution. It was found that the presence of alcohol in sulfuric acid solutions leads to an increase in the distribution coefficients both on cation exchange resins and on anion exchange resins. The possibility of using ion exchange resins for the concentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements that form strong complexes with sulfate ions in a wide range of sulfuric acid concentrations was demonstrated.

  16. Phase relations between the water-rich sulfuric acid hydrates, potential markers of thermal history on Jupiter’s icy moons

    NASA Astrophysics Data System (ADS)

    Maynard-Casely, H. E.; Brand, H. E. A.; Wallwork, K. S.

    2014-08-01

    Synchrotron X-ray powder diffraction has been used to explore the water-rich (<50 wt.% H2SO4) region of the sulfuric acid and water binary phase diagram at temperatures between 80 and 285 K. The phase relations that are determined demonstrate that, on laboratory timescales, sulfuric acid hydrates crystallize as mixtures of phases. Four forms of sulfuric acid hydrates were observed along with ice Ih, with their proportions dependent on temperature and sample H2SO4 wt.%. The charting of these phase relations has revealed a transformation between hydrate forms, which could be utilized as a marker for areas of higher heat flow on the surfaces of the Galilean ice moons.

  17. Saccharification and Fermentation of Dilute-Acid-Pretreated Freeze-Dried Switchgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bioethanol production potential of three oven-dried switchgrass germplasms (St6-1, St6-3 3E and St6-3F) containing 26.65 to 29.28% glucan, 17.92 to 19.37% xylan, and 17.74 to 19.23% lignin (dry matter basis) was investigated. Evaluation of the effect of three acid concentrations (0.5, 1.0 and 1.5% w...

  18. Soot and Sulfuric Acid from Aircraft: Is There Enough to Cause Detrimental Environmental E-kCTSs?

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Strawa, A. W.; Ferry, G. V.; Howard, S. D.; Verma, S.

    1998-01-01

    Aerosol from aircraft can affect the environment in three ways: First, soot aerosol has been implicated to cause Icing-tern ozone depletion at mid-latitudes in the lower stratosphere at a rate of approx. 5% per decade. This effect is in addition and unrelated to the polar ozone holes which are strongly influenced by heterogeneous chemistry on polar stratospheric clouds. Second, the most obvious effect of jet aircraft is the formation of visible contrails in the upper troposphere. The Salt Lake City region experienced an 8% increase in cirrus cloud cover over a 15-year period which covariates with an increase in regional commercial air traffic. If soot particles act as freezing nuclei to cause contrail formation heterogeneously, they would be linked to a secondary effect to cloud modification that very likely is climatologically important. Third, a buildup of soot aerosol could reduce the single scatter albedo of stratospheric aerosol from 0.993+0.004 to 0.98, a critical value that has been postulated to separate stratospheric cooling from warming. Thus arises an important question: Do aircraft emit sufficient amounts of soot to have detrimental effects and warrant emission controls? During the 1996 SUCCESS field campaign, we sampled aerosols in the exhaust wake of a Boeing 757 aircraft and determined emission indices for sulfuric acid (EI(sub H2SO4) = 9.0E-2 and 5.0E-1 g/kg (sub FUEL) for 75 and 675 ppm fuel-sulfur, respectively) and soot aerosol (2.2E-3 less than EI(sub SOOT) = l.lE-2 g/kg (sub FUEL)). The soot particle analysis accounted for their fractal nature, determined electron-microscopically, which enhanced the surface area by a factor of 26 and the volume 11-fold over equivalent-volume spheres. The corresponding fuel-sulfur to H2SO4 conversion efficiency was 10% (for 675 ppmm fuel-S) and 37% (for 75 ppmm fuel-S). Applying the H2SO4 emission index to the 1990 fuel use by the worlds commercial fleets of 1.3E11 kg, a conversion efficiency of 30% of 500 ppmm fuel-S would have led to an annual contribution to the atmospheric sulfur budget by aircraft of 2.E7 kg H2SO4. This is about one part in 1.E4 of anthropogenic sulfate from other sources. The soot emission index given above yielded a 1990 injection of soot aerosol by aircraft of 1.E6 kg. Thus, soot amounts to only five percent of the aerosol generated by aircraft. Its reactivity with ozone would have to be 20 times that of sulfuric acid particles to make it chemically significant. Nevertheless, the findings, of stratospheric soot loadings commensurate with aircraft fuel consumption, based on the emission index given above and the assumption of stratospheric residence times of the order of one year implicate aircraft as stratospheric polluters. A trend similar to soot of H2SO4 aerosol loading could not be deciphered, neither from in situ measurements nor SAGE II satellite extinction, against the "noise" due to volcanic eruptions. Observation of soot particles at 20 km altitude which, if emitted by aircraft were generated at 10-12 km altitude, suggests a displacement of those particles against gravity. Because eddy mixing is virtually absent in the lower stratosphere and isentropic mixing explains lofting to only about 15 km, radiometric forces acting on morphologically and chemically asymmetric soot particles must be considered a possibility. The consequence could be an extended residence time of soot against that of sulfuric acid aerosol that would lower the single scatter albedo with time.

  19. Enzymatic hydrolysis and fermentation of dilute acid pretreated cornstalk to biohydrogen

    NASA Astrophysics Data System (ADS)

    Pan, C. M.; Fan, Y. T.; Hou, H. W.

    2010-03-01

    The coupling method of acid pretreatment and enzymatic hydrolysis of cornstalk for hydrogen production was investigated in this study. Experimental results showed that temperature, pH and enzyme loading all had an individual significant influence on soluble sugar yield and Ps. The optimum condition for soluble sugar was close to that for Ps. The maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS on the optimum enzymatic hydrolysis condition which was 52 °C of temperature, pH4.8 and 9.4 IU/g of enzyme loading.

  20. Inhibitive action of indole-5-carboxylic acid towards corrosion of mild steel in deaerated 0.5 M sulfuric acid solutions

    NASA Astrophysics Data System (ADS)

    Quartarone, G.; Bonaldo, L.; Tortato, C.

    2006-09-01

    Inhibition of mild steel corrosion in deaerated 0.5 M sulfuric acid solutions containing various concentrations of indole-5-carboxylic acid is studied in the temperature range from 25 to 55 °C using weight-loss, potentiodynamic and spectrophotometric tests. The adsorptive behaviour of inhibitor is also investigated using electrochemical impedance spectroscopy measurements. The indole-5-carboxylic acid is found to shift the corrosion potentials towards more noble values. This shift indicates that the addition of inhibitor mainly affects the anodic process, raising the anodic overpotential more than that of the cathodic, i.e. the indole-5-carboxylic acid behaves as mixed-type inhibitor. Because the cathodic Tafel slopes for hydrogen reduction ( bc) are affected, the inhibitor probably affects the hydrogen reduction mechanism. The activation energy values ( Ea) indicate that the indole-5-carboxylic acid increases the activation energy of the corrosion reaction. The adsorption behaviour of indole-5-carboxylic acid follows Langmuir's isotherm. Both the low values of -?G° and its decrease with temperature suggest physical adsorption. Double layer capacitance-potential curves indicate considerable adsorption of the inhibitor in the potential range (-400 to -800 mV/ SCE).

  1. Lead sulfate nano- and microparticles in the acid plant blow-down generated at the sulfuric acid plant of the El Teniente mine, Chile.

    PubMed

    Barassi, Giancarlo M; Klimsa, Martin; Borrmann, Thomas; Cairns, Mathew J; Kinkel, Joachim; Valenzuela, Fernando

    2014-12-01

    The acid plant 'blow-down' (also called weak acid) produced at El Teniente mine in Chile was characterized. This liquid waste (tailing) is generated during the cooling and cleaning of the smelter gas prior to the production of sulfuric acid. The weak acid was composed of a liquid and a solid phase (suspended solids). The liquid phase of the sample analyzed in this study mainly contained Cu (562 mg L(-1)), SO4(2-) (32?800 mg L(-1)), Ca (1449 mg L(-1)), Fe (185 mg L(-1)), As (6 mg L(-1)), K (467 mg L(-1)) and Al (113 mg L(-1)). Additionally, the sample had a pH-value and total acidity of 0.45 and 2970 mg L(-1) as CaCO3, respectively. Hence, this waste was classified as extremely acidic and with a high metal content following the Ficklin diagram classification. Elemental analysis using atomic absorption, inductively coupled plasma, X-ray diffraction and electron microscopy showed that the suspended solids were anglesite (PbSO4) nano- and microparticles ranging from 50 nm to 500 nm in diameter. PMID:25312613

  2. Development of an accurate, sensitive, and robust isotope dilution laser ablation ICP-MS method for simultaneous multi-element analysis (chlorine, sulfur, and heavy metals) in coal samples.

    PubMed

    Boulyga, Sergei F; Heilmann, Jens; Prohaska, Thomas; Heumann, Klaus G

    2007-10-01

    A method for the direct multi-element determination of Cl, S, Hg, Pb, Cd, U, Br, Cr, Cu, Fe, and Zn in powdered coal samples has been developed by applying inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with laser-assisted introduction into the plasma. A sector-field ICP-MS with a mass resolution of 4,000 and a high-ablation rate laser ablation system provided significantly better sensitivity, detection limits, and accuracy compared to a conventional laser ablation system coupled with a quadrupole ICP-MS. The sensitivity ranges from about 590 cps for (35)Cl+ to more than 6 x 10(5) cps for (238)U+ for 1 microg of trace element per gram of coal sample. Detection limits vary from 450 ng g(-1) for chlorine and 18 ng g(-1) for sulfur to 9.5 pg g(-1) for mercury and 0.3 pg g(-1) for uranium. Analyses of minor and trace elements in four certified reference materials (BCR-180 Gas Coal, BCR-331 Steam Coal, SRM 1632c Trace Elements in Coal, SRM 1635 Trace Elements in Coal) yielded good agreement of usually not more than 5% deviation from the certified values and precisions of less than 10% relative standard deviation for most elements. Higher relative standard deviations were found for particular elements such as Hg and Cd caused by inhomogeneities due to associations of these elements within micro-inclusions in coal which was demonstrated for Hg in SRM 1635, SRM 1632c, and another standard reference material (SRM 2682b, Sulfur and Mercury in Coal). The developed LA-ICP-IDMS method with its simple sample pretreatment opens the possibility for accurate, fast, and highly sensitive determinations of environmentally critical contaminants in coal as well as of trace impurities in similar sample materials like graphite powder and activated charcoal on a routine basis. PMID:17653533

  3. Preparation and physicochemical properties of soluble dietary fiber from orange peel assisted by steam explosion and dilute acid soaking.

    PubMed

    Wang, Lei; Xu, Honggao; Yuan, Fang; Fan, Rui; Gao, Yanxiang

    2015-10-15

    The coupled pretreatment of orange peel with steam explosion (SE) and sulfuric-acid soaking (SAS) was investigated to enhance the yield and improve the functionality of soluble dietary fiber (SDF). When orange peel was pretreated by SE at 0.8MPa for 7min, combined with 0.8% SAS, the content of SDF was increased from 8.04% to 33.74% in comparison to the control and SDF prepared with SE-SAS showed the high water solubility, water-holding capacity, oil-holding capacity, swelling capacity, emulsifying activity, emulsion stability and foam stability. SDF from orange peel treated by SE-SAS exhibited significantly (p<0.05) higher binding capacity for three toxic cations (Pb, As and Cu) and smaller molecular weight (Mw=174kDa). Furthermore, differential scanning calorimetry (DSC) measurement showed that SDF from orange peel treated by SE-SAS had a higher peak temperature (170.7±0.4°C) than that of the untreated sample (163.4±0.3°C). Scanning electron micrograph (SEM) images demonstrated that the surface of SDF from orange peel treated by SE-SAS was rough and collapsed. It can be concluded that SDF from orange peel treated by SE-SAS has the higher potential to be applied as a functional ingredient in food products. PMID:25952845

  4. Mutual antagonism of sulfur dioxide and abscisic acid in their effect on stomatal aperture in broad bean (Vicia faba L. ) epidermal strips

    SciTech Connect

    Taylor, J.S.; Reid, D.M.; Pharis, R.P.

    1981-12-01

    Abscisic acid (ABA) was found to counteract the stomatal opening in Vicia faba L. caused by SO/sub 2/. The antagonism between SO/sub 2/ and ABA was mutual, and their combined effect depended upon which compound was in the greatest concentration. Stomatal apertures were monitored in detached epidermal strips floated in the light on aqueous solutions of SO/sub 2/ (sulfurous acid) and/or ABA in 0.01 molar sodium citrate buffer (pH 5.8). Low concentrations of sulfurous acid (10/sup -10/ to 10/sup -7/ molar) increased stomatal aperture, but concentrations greater than 10/sup -5/ molar decreased it. A progressive decrease in aperture size occurred as ABA was increased from 10/sup -10/ to 10/sup -5/ molar. No evidence was found for a direct chemical reaction between the buffered sulfurous acid and ABA (exogenous or endogenous). Extractable, endogenous ABA in the strips remained relatively constant after exposure to several different concentrations of sulfurous acid. A technique for quantitating ABA from methanolic extracts of small samples of epidermis (20 milligrams dry weight) using reverse phase high performance liquid chromatography is described.

  5. Synthesis of 3-aryl-4-({2-[4-(6-substituted-coumarin-3-yl)-1,3-thiazol-2-yl]hydrazinylidene}methyl\\/ethyl)-sydnones using silica sulfuric acid and their antidiabetic, DNA cleavage activity

    Microsoft Academic Search

    Gireesh Tegginamath; Ravindra R. Kamble; Pramod P. Kattimani; Sheetal B. Margankop

    A novel one-pot synthesis of sydnones appended to coumarins (4a–r) via thiazole in presence of silica sulfuric acid as a heterogeneous catalyst is discussed. The use of low cost and reusable silica sulfuric acid as catalyst makes this process feasible and convenient. Further, the title compounds were screened for their ?-amylase inhibition (antidiabetic) as well as DNA cleavage activities.

  6. Model nitride irradiated nuclear fuel: production, reaction with water and dilution in nitric acid

    SciTech Connect

    Dvoeglazov, K.; Glushenkov, A.; Sharin, A.; Arseenkov, L.; Lobachev, E.; Davydov, A.; Chebotarev, A. [JSC - A.A. Bochvar VNIINM, Rogova str. 5a, Moscow (Russian Federation)

    2013-07-01

    Samples of the model nuclear fuel (MNF) were made from separately synthesized nitride powders uranium-plutonium, zirconium, lanthanum and metal additives of simulators (Mo, Pd, Rh, Ag) fission products. Synthesis of initial nitride components was carried out from individual oxides, using a carbo-thermal restoration method. From MNF samples baked at a temperature of 1750 C. degrees, were made ceramographic specimens which were investigated by a scanning electron microscope. The analysis showed that distribution of the MNF components and structure of the samples corresponds to distribution of these components in the irradiated nitride fuel. The samples of MNF of nitride fuel were used for carrying out researches on dissolution in water and nitric acid. Experiments on studying the interaction of MNF with water have been made at 20, 50 and 80 C. degrees. The speed of leaching has been determined by a way of measuring the activity of water (Bq/l) in time. It is shown that an increase of temperature leads to an increase of the speed of leaching of plutonium. The formation of a precipitation, allegedly polymeric forms of plutonium, has been observed. The estimated speed of leaching of plutonium from MNF in water at 80 C. degrees is -0,0064 ?gPu/(mm{sup 2}*h). From elements of FP simulators, molybdenum appears to be the most significantly leached. The dissolution of MNF in nitric acid (7,8 and 9,4 mol/l) has been carried out at boiling temperature (106-109 C. degrees). During the process of dissolution, gases were emitted. The assessment of composition of the emitted gases has been carried out. During the filtering of the solutions a precipitate whose weight makes about 2% from the weight of initial fuel has been found. Precipitate represents small powder of metal with gray color. Precipitate was investigated by a scanning electron microscope. The analysis of ranges of absorption of solution showed that the Pu(VI) share to the general content of plutonium in solution can reach 40%. (authors)

  7. Determination of carbon-bonded sulfur in soils by ICP-AES after hydriodic acid reduction and hydrogen peroxide oxidation

    SciTech Connect

    Long-zhu, J. [National Natural Science Foundation of China, Beijing (China); Xiao-quan, S. [Academia Sinica, Beijing (China)

    1994-12-31

    A method has been developed for the determination of carbon-bonded sulfur in soil by ICP-AES after sequential extraction. The operating conditions of ICP-AES for the determination of sulfur was optimized. A subsample of the soil was sequentially treated with HI reduction and H{sub 2}O{sub 2} oxidation. All inorganic sulfur components and ester sulfur were reduced to H{sub 2}S by HI except pyritic sulfur, previously unidentified residue sulfur and carbon-bonded sulfur. The present study indicated that part of carbon-bonded sulfur was dissolved in the HI reducing solution, and another part of carbon-bonded sulfur was removed by H{sub 2}O{sub 2} oxidation. Therefore, carbon-bonded sulfur was the sum of HI-dissolved sulfur and H{sub 2}O{sub 2}-oxidized sulfur for oxic soils. However, pyritic sulfur should be subtracted from the sum of the two sulfur fractions in case of anoxic soils.

  8. Effect of pelleting on the recalcitrance and bioconversion of dilute-acid pretreated corn stover

    SciTech Connect

    Allison E Ray; Amber Hoover; Gary Gresham

    2012-07-01

    Background: Knowledge regarding the performance of densified biomass in biochemical processes is limited. The effects of densification on biochemical conversion are explored here. Methods: Pelleted corn stover samples were generated from bales that were milled to 6.35 mm. Low-solids acid pretreatment and simultaneous saccharification and fermentation were performed to evaluate pretreatment efficacy and ethanol yields achieved for pelleted and ground stover (6.35 mm and 2 mm) samples. Both pelleted and 6.35-mm ground stover were evaluated using a ZipperClave® reactor under high-solids, process-relevant conditions for multiple pretreatment severities (Ro), followed by enzymatic hydrolysis of the washed, pretreated solids. Results: Monomeric xylose yields were significantly higher for pellets (approximately 60%) than for ground formats (approximately 38%). Pellets achieved approximately 84% of theoretical ethanol yield (TEY); ground stover formats had similar profiles, reaching approximately 68% TEY. Pelleting corn stover was not detrimental to pretreatment efficacy for both low- and high-solids conditions, and even enhanced ethanol yields.

  9. Improvement of microwave-assisted digestion of milk powder with diluted nitric acid using oxygen as auxiliary reagent

    NASA Astrophysics Data System (ADS)

    Bizzi, Cezar A.; Barin, Juliano S.; Garcia, Edivaldo E.; Nóbrega, Joaquim A.; Dressler, Valderi L.; Flores, Erico M. M.

    2011-05-01

    The feasibility of using diluted HNO 3 solutions under oxygen pressure for decomposition of whole and non-fat milk powders and whey powder samples has been evaluated. Digestion efficiency was evaluated by determining the carbon content in solution (digests) and the determination of Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Pb and Zn was performed by inductively coupled plasma optical emission spectrometry and Hg by chemical vapor generation coupled to inductively coupled plasma mass spectrometry. Samples (up to 500 mg) were digested using HNO 3 solutions (1 to 14 mol L - 1 ) and the effect of oxygen pressure was evaluated between 2.5 and 20 bar. It was possible to perform the digestion of 500 mg of milk powder using 2 mol L - 1 HNO 3 with oxygen pressure ranging from 7.5 to 20 bar with resultant carbon content in digests lower than 1700 mg L - 1 . Using optimized conditions, less than 0.86 mL of concentrated nitric acid (14 mol L - 1 ) was enough to digest 500 mg of sample. The accuracy was evaluated by determination of metal concentrations in certified reference materials, which presented an agreement better than 95% (Student's t test, P < 0.05) for all the analytes.

  10. Thermopressurized diluted phosphoric acid pretreatment of ligno(hemi)cellulose to make free sugars and nutraceutical oligosaccharides.

    PubMed

    Tiboni, Marcela; Grzybowski, Adelia; Baldo, Gizele Rejane; Dias, Edson Flausino; Tanner, Robert D; Kornfield, Julia Ann; Fontana, José Domingos

    2014-06-01

    Ligno(hemi)cellulosics (L(h)Cs) as sugarcane bagasse and loblolly pine sawdust are currently being used to produce biofuels such as bioethanol and biobutanol through fermentation of free sugars that are often obtained enzymatically. However, this bioconversion requires a pretreatment to solubilize the hemicellulose fractions, thus facilitating the action of the cellulolytic enzymes. Instead of the main free monosaccharides used in these current models, the modulation of thermopressurized orthophosphoric acid as a pretreatment, in the ranges of 3-12 atm and pH 1.5-2.5, can produce nondigestible oligosaccharides (NDOS) such as xylo-oligosaccharides (XOS) because heteroxylan is present in both types of hardwood and softwood hemicelluloses. A comparative thin-layer chromatographic analysis of the hydrolytic products showed the best conditions for NDOS production to be 7 atm/water, pH 2.25 and 2.50, and 8.5 atm/water for both sources. Particular hydrolysates from 7 atm (171 °C) at pHs 2.25 and 2.50 both for cane bagasse and pine sawdust, with respective oligosaccharide contents of 57 and 59 %, once mixed in a proportion of 1:1 for each plant source, were used in vitro as carbon sources for Bifidobacterium or Lactobacillus. Once both bacteria attained the stationary phase of growth, an unforeseen feature emerged: the preference of B. animalis for bagasse hydrolysates and, conversely, the preference of L. casei for pine hydrolysates. Considering the fact that nutraceutical oligosaccharides from both hemicelluloses correspond to higher value-added byproducts, the technology using a much diluted thermopressurized orthophosphoric acid pretreatment becomes an attractive choice for L(h)Cs. PMID:24747989

  11. Catalytic sulfur degassing

    SciTech Connect

    Baker, D.C.

    1988-07-05

    A process is described for the preparation of (1) synthesis gas reduced in solids and acidic gases and (2) elemental sulfur which comprises (a) treating coal, shale or tar sands with oxygen to produce a synthesis gas stream containing inorganic sulfide; (b) recovering slag particles from the treatment of coal in step (a) and selecting particles thereof suitable for use as a catalyst carrier; (c) treating the slag from step (b) with the synthesis gas substantially free of slag particles to deposit on the surface slag particles a catalytic amount of at least one metal sulfide; (d) treating the synthesis gas from step (c) to remove acidic gases suitable for sulfur production; (e) converting the acid gases from step (d) to liquid sulfur; and (f) contacting the liquid sulfur with the catalytic slag particles from step (c) to reduce the hydrogen sulfide and hydrogen polysulfide content of the sulfur.

  12. Deposition of copper multilayers on Au(111) in sulfuric acid solution: An electrochemical scanning tunneling microscopy study

    NASA Astrophysics Data System (ADS)

    Madry, B.; Wandelt, K.; Nowicki, M.

    2015-07-01

    The co-adsorption of submono-, mono- and multi-layers of Cu with sulfate anions on a Au(111) electrode surface was investigated in electrochemical environment (0.1 mM CuSO4 + 0.1 M H2SO4) by cyclic voltammetry (CV) and in-situ scanning tunneling microscopy (STM). Correlated with the STM investigations the CV measurements indicate co-adsorption/-desorption processes of Cu of submono-, mono- and multi-layer coverages with sulfuric acid species on Au(111). The formation of a quasi-hexagonal Moiré superstructure on terraces of copper multilayers was observed in situ by STM. In detail the observed Moiré-structure is similar but not identical to the one observed on the (111) surface of bulk copper. High resolution STM images show the formation of a (?{ 3} ×?{ 7})-like sulfate structure on all multilayer copper terraces.

  13. Application of the kinetic-thermodynamic model for inhibition of acid corrosion of steel by inhibitors containing sulfur and nitrogen

    SciTech Connect

    Abd-El-Nabey, B.A.; Khamis, E.; Ramadan, M.S.; El-Gindy, A. [Alexandria Univ. (Egypt). Chemistry Dept.

    1996-09-01

    Corrosion inhibition characteristics of 4 selected S-alkylisothioronium halides on steel in sulfuric acid media were investigated at 30 C, 40 C, 50 C, and 60 C. The number of active sites on the metal occupied by a molecule of the inhibitor (1/y) and the binding constants (K) of the inhibitor to the active sites were calculated at the different temperatures. Activation free energies, enthalpies, and entropies for the inhibition processes were determined from rate-constant data measured at 30 C, 40 C, 50 C, and 60 C at two fixed inhibitor concentrations. Data were compared and fitted to a published kinetic-thermodynamic model. Results were compared with fits obtained from application of Langmuir, Frumkin, and Flory-Huggins isotherms. Results also were correlated to the chemical structure of the inhibitors, the length of the alkyl chain of the cation, and the type of the anion.

  14. Corrosion phenomena of alloy 625 in aqueous solutions containing sulfuric acid and oxygen under subcritical and supercritical conditions

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E. [Forschungszentrum Karlsruhe (Germany)

    1998-12-31

    Corrosion phenomena of alloy 625 pressure tubes were investigated in aqueous solutions containing up to 0.2 mol/kg sulfuric acid and up to 1.44 mol/kg oxygen. Applied maximum temperatures and pressures were 500 C, and 38 MPa, respectively. Corrosion started at temperatures around 150 C with intergranular attack. Above 250 C, the whole surface of the alloy was attacked, shallow pits and deep intergranular attack appeared. This behavior can be explained by transpassive dissolution of the protecting Cr(III) oxide layer and leads to severe material loss. The upper temperature limit of severe corrosion at an experimental pressure of 24 MPa was about 390 C. As temperature was increased further and the density of the solution dropped to low values, only slight corrosion was detected.

  15. Enrichment adsorption of a labile substance to the surface of particular mineral particles in river water as investigated by SEM-EDX and dilute-acid extraction/ICP-MS.

    PubMed

    Kyotani, Tomohiro; Koshimizu, Satoshi

    2003-06-01

    The selective enrichment behavior of a labile substance, such as hydroxides, to the surface of particular mineral particles in river water was clarified by scanning electron microscopy/energy dispersive X-ray microanalysis (SEM-EDX). Individual particles other than diatom collected on a 0.45 microm filter from the Fuji and Sagami rivers, central Japan, were analyzed by SEM-EDX and classified into seventeen groups according to the chemical composition and shape. Phosphorus, sulfur, chlorine, manganese and copper detected in each particle collected on the 0.45 microm filter could be successfully used as effective indicators of labile substance secondarily formed and adsorbed afresh in river water, because the detection frequencies of such elements are quite low, or negligible, in fresh mineral particles derived from igneous rocks. The labile substance adsorbed on mineral particles collected on the 0.45 microm filter was also evaluated by dilute-acid leaching, followed by inductively coupled plasma mass spectrometry (ICP-MS). Almost all parts of the manganese detected in individual particles were those adsorbed afresh as hydroxides together with iron and aluminum. Also, anionic elements, such as phosphorus, sulfur and chlorine, formed complexes with the hydroxides and/or were incorporated in them. Mg and/or Ca-rich aluminosilicate groups were the most effective adsorbers of such labile species. However, Si-rich and Na-, K- and Na-Ca rich aluminosilicates did not significantly adsorb the labile substance. Consequently, the remarkable selectivity was clarified in the adsorption process of labile substance to individual mineral particles in river water. PMID:12834221

  16. Determination of nickel in the solution resulted from sulfuric-acid leaching of the active mass of the nickel-oxide electrode of the nickel-iron battary

    Microsoft Academic Search

    E. N. Volkova; A. I. Demidov

    2009-01-01

    A nickel content was determined in the solution resulted from sulfuric-acid leaching of the active mass of the nickel-oxide\\u000a electrode of an exhausted nickel-iron battery by complexometric titration with visual indication of an equivalence point.

  17. Sulfur, Protein Size Distribution, and Free Amino Acids in Flour Mill Streams and Their Relationship to Dough Rheology and Breadmaking Traits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to evaluate differences in sulfur content, protein size distribution, and free amino acids among flour mill streams (FMS) and their relationships to dough rheology and breadmaking traits. Information from this study would likely lead to more precise blending of FMS in comme...

  18. IMPACT OF PRIMARY SULFATE AND NITRATE EMISSIONS FROM SELECTED MAJOR SOURCES. PHASE 2: SULFURIC ACID PLANT AND PULP AND PAPER MILL

    EPA Science Inventory

    The report covers Phase two of a two phase study of the near source impacts of primary sulfate and nitrate emission sources. The phase two portion of the study was an investigation of the impact of the emissions from a sulfuric acid plant, and a pulp and paper mill. The study was...

  19. The waste sulfuric acid lake of the TiO 2-plant at Armyansk, Crimea, Ukraine. Part I. Self-Sealing as an environmental protection mechanism

    Microsoft Academic Search

    P. F. M. van Gaans; P VANGAANS

    1997-01-01

    The TiO2-plant at Armyansk, in operation since 1969, discharges its waste sulfuric acid and other effluents into an ‘acid collector’ of 42 km2 surface area. Under the semi-arid climatic conditions, such a surface represents the equilibrium between effluent production and evaporation. In the course of its operation, the pH of the lake has slowly decreased to a value of 0.85.

  20. In-situ STM study of the initial stages of corrosion of Cu(100) electrodes in sulfuric and hydrochloric acid solution

    Microsoft Academic Search

    M. R. Vogt; A. Lachenwitzer; O. M. Magnussen; R. J. Behm

    1998-01-01

    An in-situ scanning tunneling microscopy (STM) study of Cu(100) electrode surfaces in sulfuric and hydrochloric acid solutions in the potential range ?0.6 to ?0.1 V versus AgAgCl (KClsat) is presented, revealing the surface structure and dynamics in the double-layer region and providing detailed structural data on the initial stages of anodic Cu dissolution. After preparation by electropolishing in phosphoric acid,

  1. Atmospheric conversion of sulfur dioxide to particulate sulfate and nitrogen dioxide to particulate nitrate and gaseous nitric acid in an urban area

    Microsoft Academic Search

    M. I Khoder

    2002-01-01

    Sulfur dioxide, nitrogen dioxide, particulate sulfate and nitrate, gaseous nitric acid, ozone and meteorological parameters (temperature and relative humidity) were measured during the winter season (1999–2000) and summer season (2000) in an urban area (Dokki, Giza, Egypt). The average particulate nitrate concentrations were 6.20 and 9.80 ?gm?3, while the average gaseous nitric acid concentrations were 1.14 and 6.70 ?gm?3 in

  2. Regulation of fatty acid oxidation and triglyceride and phospholipid metabolism by hypolipidemic sulfur-substituted fatty acid analogues.

    PubMed

    Skorve, J; Asiedu, D; Rustan, A C; Drevon, C A; al-Shurbaji, A; Berge, R K

    1990-09-01

    The mechanisms behind the hypotriglyceridemic effect of 1,10-bis(carboxymethylthio)decane (3-thiadicarboxylic acid) and tetradecylthioacetic acid and the development of fatty liver caused by 3-tetradecylthiopropionic acid (Aarsland et al. 1989. J. Lipid Res. 30: 1711-1718.) were studied in the rat. Repeated administration of S-substituted non-beta-oxidizable fatty acid analogues to normolipidemic rats resulted in a time-dependent decrease in plasma triglycerides, phospholipids, and free fatty acids. This was accompanied by an acute reduction in the liver content of triglycerides and an increase in the hepatic concentration of phospholipids. Mitochondrial fatty acid oxidation was stimulated, whereas lipogenesis was inhibited. The activity of phosphatidate phosphohydrolase decreased while the activity of CTP:phosphocholine cytidylyltransferase increased. These results suggest that the observed triglyceride-lowering effect was due to increased mitochondrial fatty acid oxidation accompanied by a reduction in the availability of the substrate i.e., free fatty acid, along with an enzymatic inhibition (phosphatidate phosphohydrolase). Administration of 3-tetradecylthiopropionic acid led to a drastic increase in the hepatic triglyceride content. Levels of plasma triglyceride phospholipid and free fatty acid also increased. Phosphatidate phosphohydrolase activity was stimulated whereas CTP:phosphocholine cytidylyltransferase was inhibited. Mitochondrial fatty acid oxidation was decreased. These data indicate that the development of fatty liver as an effect of 3-tetradecylpropionic acid is probably due to accelerated triglyceride biosynthesis, which is mediated by an increase in the availability of fatty acid along with stimulation of phosphatidate phosphohydrolase. The results of the present study speak strongly in favor of the hypothesis that phosphatidate phosphohydrolase is a major rate-limiting enzyme in triglyceride biosynthesis. Furthermore, they point out that the biosynthesis of triglycerides and phospholipids might be coordinately regulated. Such regulation is possibly mediated via phosphatidate phosphohydrolase and CTP:phosphocholine cytidylyltransferase. Whether the increase in hepatic phospholipids via increased CDP-pathway accounts for an increase of lipid components for proliferation of peroxisomes (3-thiadicarboxylic acid and tetradecylacetic acid) should be considered. PMID:2174075

  3. Photoluminescence properties of porous anodic aluminium oxide membranes formed in mixture of sulfuric and oxalic acid

    NASA Astrophysics Data System (ADS)

    Li, Yan; Wang, Cheng-Wei; Zhao, Li-Rong; Liu, Wei-Min

    2009-02-01

    Porous anodic aluminium oxide (AAO) membranes with ordered nanopore arrays were fabricated electrochemically in the mixture electrolytes with various volume ratios of 0.3 M H2SO4 and 0.3 M C2H2O4. Photoluminescence (PL) properties of as-prepared AAO membranes were investigated. It was found that a 290 nm emission was observed in the AAO samples formed in the H2SO4 electrolyte and a 325 nm emission in the samples formed in the C2H2O4 electrolyte, respectively. For the AAO membranes anodized in the mixture electrolytes, both 290 and 325 nm emissions appeared together; moreover, the 290 nm peak was weakened, and the 325 nm peak was enhanced dramatically. It is suggested that the 290 and 325 nm emissions could be attributed to the luminescent centres transformed from sulfuric and oxalic impurities, respectively, and that nonradiative energy transfer occurs between these two kinds of PL centres.

  4. ECUT: Energy Conversion and utilization Technologies program biocatalysis research activity. Generation of chemical intermediates by catalytic oxidative decarboxylation of dilute organic acids

    NASA Technical Reports Server (NTRS)

    Distefano, S.; Gupta, A.; Ingham, J. D.

    1983-01-01

    A rhodium-based catalyst was prepared and preliminary experiments were completed where the catalyst appeared to decarboxylate dilute acids at concentrations of 1 to 10 vol%. Electron spin resonance spectroscoy was used to characterize the catalyst as a first step leading toward modeling and optimization of rhodium catalysts. Also, a hybrid chemical/biological process for the production of hydrocarbons has been assessed. These types of catalysts could greatly increase energy efficiency of this process.

  5. Conditioning of dilute-acid pretreated corn stover hydrolysate liquors by treatment with lime or ammonium hydroxide to improve conversion of sugars to ethanol

    Microsoft Academic Search

    Edward W. Jennings; Daniel J. Schell

    2011-01-01

    Dilute-acid pretreatment of lignocellulosic biomass enhances the ability of enzymes to hydrolyze cellulose to glucose, but produces many toxic compounds that inhibit fermentation of sugars to ethanol. The objective of this study was to compare the effectiveness of treating hydrolysate liquor with Ca(OH)2 and NH4OH for improving ethanol yields. Corn stover was pretreated in a pilot-scale reactor and then the

  6. Thermodynamic Analysis of the Cu-As-S-(O) System Relevant to Sulfuric Acid Baking of Enargite at 473 K (200 °C)

    NASA Astrophysics Data System (ADS)

    Safarzadeh, M. Sadegh; Miller, Jan D.; Huang, Hsin H.

    2014-04-01

    While the growing demand for copper has compelled the industry to adapt new technologies for the treatment of copper-arsenic (enargite) concentrates, the refractory nature of such concentrates combined with the troublesome presence of arsenic has created a major metallurgical and environmental challenge. Preliminary results of the acid bake-leach process at the University of Utah have shown some potential advantages for the treatment of enargite concentrates. While the transformation of enargite to copper sulfate, arsenolite, and elemental sulfur has already been established experimentally, thermodynamic evaluation of the sulfuric acid baking process provides further understanding which should be useful. In this article, the available thermodynamic data for the species involved in the Cu-As-S-O system are compiled. These data were used to calculate the phase stability (Kellogg) diagrams as well as equilibrium compositions at 473 K (200 °C) using the STABCAL and HSC Chemistry® 5.1 software packages. The equilibrium composition calculations indicate that enargite can transform to copper sulfate either directly or through chalcocite and/or covellite. The major gaseous species during baking were found to be SO2 and H2O. The results of the thermodynamic calculations were further compared with two confirmatory baking experiments involving a high-quality enargite sample. The condensed reaction products from sulfuric acid baking based on XRD results include CuSO4, As2O3, CuO·CuSO4, and S8 under both neutral and oxidative conditions. While all these compounds were predicted through equilibrium calculations, some of the predicted compounds were not detected in the sulfuric acid-baked enargite. None of the calculations indicated any appreciable amounts of arsenic-bearing gases at the baking temperature of 473 K (200 °C). Consistent with thermodynamic predictions, no H2S gas was detected during the sulfuric acid baking experiment. Approximately, 80 pct of the baked enargite samples were leached in water.

  7. The effect of dietary sulfur on the metabolism of long chain polyunsaturated fatty acids

    SciTech Connect

    Chen, M.F.

    1988-01-01

    The effect of methionine-supplemented diet on the metabolism of polyunsaturated fatty acids was studied by comparing results of control and cysteine-supplemented diets in rats. Adult Sprague-Dawley rats were fed for a period of 17 days one of the following diets: control, cysteine-supplemented, and/or methionine-supplemented. On the last day of the feeding period, the rats were administered either (1-{sup 14}C) arachidonic acid (AA) or (1-{sup 14}C) eicosapentaenoic acid (EPA) by stomach tube five hours before sacrificing. The cyclooxygenase activity in liver microsomes, the apparent Km of the fatty acyl-CoA synthetase in liver and brain homogenates, and the incorporation of polyunsaturated fatty acids into the phosphatidylinositol fraction of brain, heat, lung, spleen, and kidney tissues were analyzed.

  8. SYNTHESES WITH SULFUR CONTAINING NUCLEOPHILES. I. REACTION OF SULFINIC ACIDS WITH 2-HALOGENO-2-NITROETHENYLARENES

    Microsoft Academic Search

    D. I. Aleksiev; S. Ivanova

    1995-01-01

    The interaction between unsubstituted and p-substituted benzenesulfinic acids and various 2-halogeno-2-nitroethenylarenes at mol ratios sulfinic acid:2-halogeno-2-nitroethenylarene = 1:1 and 2:1 was studied at 0°C and 20°C for 16 and 96 hours. It was proved that, depending on experimental conditions, the reaction results not only in ?-halogeno-?-nitro-?-sulfones but also in ?-nitro-?,?-disulfones, which are obtained by a consecutive process. The quantitative ratio

  9. Degrees of polymerization (DP) and DP distribution of dilute acid-hydrolyzed products of alkali-treated native and regenerated celluloses

    Microsoft Academic Search

    Takuya Isogai; Masahiro Yanagisawa; Akira Isogai

    2008-01-01

    Three groups of cellulose II samples, 20% NaOH-treated native celluloses (M-native celluloses), commercial regenerated celluloses\\u000a and those treated with 20% NaOH (M-regenerated celluloses), were subjected to dilute acid hydrolysis at 105 °C to obtain so-called\\u000a leveling-off degrees of polymerization (LODP). Molecular mass parameters of the acid-hydrolyzed products were analyzed by\\u000a SEC-MALLS using 1% LiCl\\/DMAc as an eluent. The LODP values were

  10. The inhibition effect of some amino acids towards Pb–Sb–Se–As alloy corrosion in sulfuric acid solution

    Microsoft Academic Search

    Z. Ghasemi; A. Tizpar

    2006-01-01

    The inhibition effect of three amino acids towards the corrosion of Pb–Sb–Se–As alloy in 1.28 s.g. H2SO4 solution was investigated with linear polarization and weight loss measurements methods. The results drawn from two different techniques are comparable. The used amino acids were tryptophane, proline and methionine. The effect of inhibitor concentration and temperature against inhibitor action was investigated. It was

  11. Inhibitory effect of some amino acids on corrosion of Pb–Ca–Sn alloy in sulfuric acid solution

    Microsoft Academic Search

    M. A. Kiani; M. F. Mousavi; S. Ghasemi; M. Shamsipur; S. H. Kazemi

    2008-01-01

    The present article describes the inhibition effect of amino acids cysteine (Cys), methionine (Met) and alanine (Ala), towards the corrosion of lead-alloy (Pb–Ca–Sn) in H2SO4 solution by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), weight loss measurement and scanning electron microscopy (SEM) methods. The influence of inhibitor concentration, temperature and time on inhibitory behavior of the amino acids was investigated. The

  12. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montańo, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2015-04-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt%) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and methylglyoxal have the potential to produce significant organic aerosol mass and therefore could potentially impact chemical, optical and/or cloud-forming properties of aerosols, especially if the products partition to the aerosol surface.

  13. Protective effects of salicylic acid and vitamin C on sulfur dioxide-induced lipid peroxidation in mice.

    PubMed

    Zhao, Huiping; Xu, Xin; Na, Jie; Hao, Lin; Huang, Linli; Li, Guangzhe; Xu, Qiang

    2008-07-01

    The antioxidant effects of exogenous salicylic acid (SA) and vitamin C (Vit C) on the oxidative stress induced by 56 mg/m(3) of sulfur dioxide (SO2) in mouse livers and brains were investigated. The exposure of SO2 caused significant elevation of thiobarbituric acid-reactive substance (TBARS) levels and reduction of enzyme activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in brain and liver, accompanied by a decrease in relative growth rate, when compared with controls. Application of moderate concentrations of SA and Vit C markedly reduced the SO2-induced elevation of TBARS levels, with 5.5 mg/kg SA or 200 mg/kg Vit C being most effective. In contrast to the decrease of TBARS levels, the levels of SOD, POD, and CAT in liver and brain were significantly increased in comparison with controls. The polyacrylamide gel electrophoresis (PAGE) of total liver proteins showed that the SO2 inhalation caused a 30-kD protein band disappearance compared with the control. However, the band remained unchanged in the samples treated with 5.5 and 8.25 mg/kg SA or 100, 200, and 400 mg/kg Vit C. Therefore, this protein band may serve as a marker for the damage induced by SO2 and an additional basis for drug screening and selection. PMID:18645726

  14. A critical evaluation of digestion procedures for coffee samples using diluted nitric acid in closed vessels for inductively coupled plasma optical emission spectrometry.

    PubMed

    Castro, Jacira T; Santos, Elisāngela C; Santos, Wagna P C; Costa, Letķcia M; Korn, Mauro; Nóbrega, Joaquim A; Korn, Maria Graēas A

    2009-06-15

    The efficiency of diluted nitric acid solutions for digesting regular coffee samples was evaluated employing two closed vessel procedures: one was based on microwave-assisted heating and the other was based on conductive heating using pressurized Parr bomb. The efficiency of digestion was evaluated by determining residual carbon content (RCC) and residual acidity. The digestion was effective using both procedures, i.e. there were no solid residues after the decomposition reactions when using up to 3.5 mol L(-1) nitric acid solutions. It was demonstrated that the digestion procedures are critically dependent on reactions occurring in liquid and gas phase and that the formation of NO and its conversion to NO2 by O2 exerts a major effect in the oxidation of organic matter. These processes are more effective in closed vessels heated by microwave radiation due to the greater volume of these flasks and the temperature gradient that exists during the first step of the digestion process. The proposed model for the digestion processes in diluted nitric acid solution is corroborated by data about consumption of acid during the digestion and by measuring the pressure during the whole process. PMID:19362204

  15. Design, Synthesis and Biological Evaluation of Sulfur-Containing 1,1-Bisphosphonic Acids as Antiparasitic Agents

    PubMed Central

    Recher, Marion; Barboza, Alejandro P.; Li, Zhu-Hong; Galizzi, Melina; Ferrer-Casal, Mariana; Szajnman, Sergio H.; Docampo, Roberto; Moreno, Silvia N. J.

    2013-01-01

    As part of our efforts aimed at searching for new antiparasitic agents, 2-alkylmercaptoethyl-1,1-bisphosphonate derivatives were synthesized and evaluated against Trypanosoma cruzi, the etiologic agent of Chagas disease, and Toxoplasma gondii, the responsible agent for toxoplasmosis. Many of these sulfur-containing bisphosphonates were potent inhibitors against the intracellular form of T. cruzi, the clinically more relevant replicative form of this parasite, and tachyzoites of T. gondii targeting T. cruzi or T. gondii farnesyl diphosphate synthases (FPPSs), which constitute valid targets for the chemotherapy of these parasitic diseases. Interestingly, long chain length sulfur-containing bisphosphonates emerged as relevant antiparasitic agents. Taking compounds 37, 38, and 39 as representative members of this class of drugs, they exhibited ED50 values of 15.8 ?M, 12.8 ?M, and 22.4 ?M, respectively, against amastigotes of T. cruzi. These cellular activities matched the inhibition of the enzymatic activity of the target enzyme (TcFPPS) having IC50 values of 6.4 ?M, 1.7 ?M, and 0.097 ?M, respectively. In addition, these compounds were potent anti-Toxoplasma agents. They had ED50 values of 2.6 ?M, 1.2 ?M, and 1.8 ?M, respectively, against T. gondii tachyzoites, while they exhibited a very potent inhibitory action against the target enzyme (TgFPPS) showing IC50 values of 0.024 ?M, 0.025 ?M, and 0.021 ?M, respectively. Bisphosphonates bearing a sulfoxide unit at C-3 were also potent anti-Toxoplasma agents, particularly those bearing long aliphatic chains such as 43–45, which were also potent antiproliferative drugs against tachyzoites of T. gondii. These compounds inhibited the enzymatic activity of the target enzyme (TgFPPS) at the very low nanomolar range. These bisphosphonic acids have very good prospective not only as lead drugs but also as potential chemotherapeutic agents. PMID:23318904

  16. Hydration of aircraft engine soot particles under plume conditions: Effect of sulfuric and nitric acid processing

    NASA Astrophysics Data System (ADS)

    Shonija, N. K.; Popovicheva, O. B.; Persiantseva, N. M.; Savel'Ev, A. M.; Starik, A. M.

    2007-01-01

    Hydration properties of original engine soot produced by burning TC1 aviation kerosene in aircraft engine combustor are studied under simulated plume conditions. Engine-generated soot demonstrates a high level of water uptake due to the existence of fraction of impurities originating within an engine. It contains 13.5 wt% water soluble compounds including 3.5 wt% organic and inorganic sulfates. Total amount of water vapor absorbed by engine soot particles increases with the temperature decrease in the exhaust plume and reaches 18 wt% at threshold contrail formation conditions. Chemical processing of soot particles in the young plume through the coagulation with sulfate aerosols and H2SO4/H2O heterogeneous nucleation leads to 0.2 wt% of H2SO4 accumulating at high fuel sulfur content. Such a small amount of additional H2SO4 cannot result in the increase of water uptake by the fraction of impurities of engine-generated soot particles but may activate the hydrophobic fraction that originally contains a negligible amount of water soluble compounds. HNO3 processing may compete with H2SO4 in respect to increase of water uptake. It is inferred that the fraction of impurities of engine-generated soot plays a key role in the CCN formation in the aircraft plume.

  17. The inhibition effect of some amino acids towards Pb Sb Se As alloy corrosion in sulfuric acid solution

    NASA Astrophysics Data System (ADS)

    Ghasemi, Z.; Tizpar, A.

    2006-03-01

    The inhibition effect of three amino acids towards the corrosion of Pb-Sb-Se-As alloy in 1.28 s.g. H 2SO 4 solution was investigated with linear polarization and weight loss measurements methods. The results drawn from two different techniques are comparable. The used amino acids were tryptophane, proline and methionine. The effect of inhibitor concentration and temperature against inhibitor action was investigated. It was found that these inhibitors act as good inhibitors for the corrosion of lead alloy in H 2SO 4 solution. Increasing inhibitor concentration increases the inhibition efficiency. It was found that adsorption of used amino acids on lead alloy surface follows Langmuir isotherm.

  18. Interaction of manganese(IV) oxide with aqueous solutions of citric and sulfuric acids

    NASA Astrophysics Data System (ADS)

    Godunov, E. B.; Artamonova, I. V.; Gorichev, I. G.; Lainer, Yu. A.

    2012-01-01

    The kinetic laws of the dissolution of manganese(IV) oxide using citric acid are studied as functions of the temperature and pH of a solution and the concentration of citric acid. The following kinetic parameters of the dissolution are calculated: the reaction rate, the reaction order with respect to citrate ions ( n = 0.6), and the activation energy ( E a = 47.4 kJ/mol). The optimum conditions favoring an increase in the leaching intensity and economical consumption of the reactants are experimentally determined.

  19. Hydrates in supersaturated binary sulfuric acid-water vapor: A reexamination

    NASA Astrophysics Data System (ADS)

    Jaecker-Voirol, A.; Mirabel, P.; Reiss, H.

    1987-10-01

    The influence of hydrates formation on the energetics of nucleation has been reexamined. The distribution Nh of hydrates containing one acid molecule and h water molecules has been calculated as a function of the relative humidity and acid vapor concentration. A new formula giving the reversible work required to form a droplet has been derived. Hydrate formation can exert an appreciable effect on the energetics of nucleation in the H2SO4-H2O system and must be included in any theory of nucleation rate.

  20. Ion Clusters in Nucleation Experiments in the CERN Cloud Chamber: Sulfuric Acid + Ammonia + Dimethyl Amine + Oxidized Organics

    NASA Astrophysics Data System (ADS)

    Worsnop, D. R.; Schobesberger, S.; Bianchi, F.; Ehrhart, S.; Junninen, H.; Kulmala, M. T.

    2012-12-01

    Nucleation from gaseous precursors is an important source of aerosol particles in the atmosphere. The CLOUD experiment at CERN provides exceptionally clean and well-defined experimental conditions for studies of atmospheric nucleation and initial growth, in a 26 m3 stainless-steel chamber. In addition, the influence of cosmic rays on nucleation and nanoparticle growth can be simulated by exposing the chamber to a pion beam produced by the CERN Proton Synchrotron. A key to understanding the mechanism by which nucleation proceeds in the CLOUD chamber is the use of state-of-the-art instrumentation, including the Atmospheric Pressure interface Time-Of-Flight (APi-TOF) mass spectrometer. The APi-TOF is developed by Tofwerk AG, and Aerodyne Research, Inc., and typically obtains resolutions between 4000 and 6000 Th/Th and mass accuracies < 10 ppm. Sampling occurs directly from atmospheric pressure through a critical orifice. Ions are then focused and guided to the time-of-flight mass spectrometer, while passing through differentially pumped chambers. No ionization of the sampled aerosol is performed; only ions charged in the chamber are detected in the current configuration. For all studied chemical systems, the APi-TOF detected ion clusters that could directly be linked to nucleation. The composition of these ion clusters could be determined based on their exact masses and isotopic patterns. Aided by the chamber's cleanliness and the possibility of enhancing ion concentrations by using CERN's pion beam, a remarkably large fraction of the ion spectra could be identified, even for more complex chemical systems studied. For the ammonia-sulfuric acid-water system, for instance, growing clusters containing ammonia (NH3) and sulfuric acid (H2SO4) were observed up to 3300 Th. Adding dimethyl amine and/or pinanediol into the CLOUD chamber, altered the chemical compositions of the observed ion clusters accordingly. Cluster growth then included mixtures of sulfuric acid and dimethyl amine and/or a wide range of pinanediol oxidation products. The initial growth of clusters/particles was studied from smallest clusters upwards, using a range of employed instrumentation. Condensation particle counters (such as the Particle Size Magnifier, PSM, by Airmodus Oy), for instance, were specially modified to obtain aerosol number size distributions down to the size of molecular clusters at 1.1 nm (mobility equivalent diameter), and at a time resolution of 2 min. The APi-TOF recorded ion spectra every 5 s; and time series for ion cluster appearance could be usually obtained at a practical time resolution of about 30 s. Therefore, the initial growth of ions could be resolved molecule by molecule, while the largest observable ion clusters corresponded to mobility equivalent diameters of 1.8-2.1 nm. Appearance times and growth rates determined from APi-TOF spectra agreed well with those observed by other instruments such as the PSM.

  1. Suicide due to sulfuric acid ingestion in a case of major depressive disorder

    PubMed Central

    Rao, K. Nagaraja; Sudarshan, C. Y.

    2015-01-01

    A case of Sulphuric acid ingestion with an intention to commit suicide in a patient of Major Depressive Disorder which resulted in death is reported. Aspects of this mode of suicide and legal issues concerning suicide in mentally ill patient have been discussed.

  2. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    PubMed

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface. PMID:23755692

  3. Catalyst Activity and Post-operation Analyses of Pt/TiO2 (Rutile) Catalysts Used in the Sulfuric Acid Decomposition Reaction

    SciTech Connect

    Lucia M. Petkovic; Daniel M. Ginosar; Harry W. Rollins; Kyle C. Burch; Patrick J. Pinhero; Helen H. Farrell

    2007-06-01

    Production of hydrogen by splitting of water at lower temperatures than by direct thermal decomposition can be achieved by a series of particular chemical reactions that establish a thermochemical cycle [1]. Among the high number of thermochemical water-splitting cycles proposed in the literature [2], the sulfur-based group is of considerable interest. All the sulfur-based cycles employ the catalytic decomposition of sulfuric acid into SO2 and O2. The produced O2 corresponds to the O2 generated from water in the overall cycle. Research performed at the Idaho National Laboratory [3] has found that even one of the most stables catalysts, Pt supported on low surface area titania, deactivates with time on stream (TOS). To develop an understanding of the factors that cause catalyst deactivation, samples of 1% Pt supported on titania (rutile) catalyst were submitted to flowing concentrated sulfuric acid at 1123 K and atmospheric pressure for different TOSs between 0 and 548 h and a number of chemical and spectroscopic analyses applied to the spent samples.

  4. The effect of the use of NP305 masks in improving respiratory symptoms in workers exposed to sulfuric acid mists in plating and pickling units

    PubMed Central

    Rafieepour, Athena; Dolatshahi, Narges Gholamzadeh Taj; Ghasemkhan, Alireza Haj; Asghari, Mehdi; Sadeghian, Marzieh; Asadi, Ali

    2013-01-01

    Background: Plating and pickling processes are the most effective ways for increasing the strength of metal structures, and workers in these units are exposed to various contaminants, including acid mists. The aim of this study was to investigate the effect of protective masks in decreasing the respiratory symptoms and the aerobic capacity of workers that are exposed sulfuric acid mist. Methods: This interventional study was based on National Institute for Occupational Safety and Health (NIOSH) standard 7903 in which silica gel tubes are used for sampling the air in plating and pickling units for eight hours. After the samples were acquired and prepared, they were analyzed by ion chromatography and were compared with the American Conference of Governmental Industrial Hygienists (ACGIH) exposure limits. Respiratory symptoms were evaluated among two sets of test subjects, i.e., those who used NP305 masks in the workplace and those who did not use the mask. Results: The results showed that the concentration of sulfuric acid mist in the plating units was greater than the exposure limits, and concentrations at this level can cause an increase in symptoms related to irritation of the airway and a slight decrease in respiratory capacity. In this study, smoking had no significant effect on the severity of pulmonary dysfunction. Conclusion: The results indicated that the use of an NP305 mask is effective for decreasing symptoms resulting from exposure to sulfuric acid mist and improving respiratory capacity. PMID:26120392

  5. Nitrogen lowers the sulfur amino acid content of soybean (Glycine max [L.] Merr.) by regulating the accumulation of Bowman-Birk protease inhibitor.

    PubMed

    Krishnan, Hari B; Bennett, John O; Kim, Won-Seok; Krishnan, Ammulu Hari; Mawhinney, Thomas P

    2005-08-10

    Soybeans in general contain 35-40% protein. Efforts are underway to increase further this protein content, thus enhancing their nutritive value. Even though higher protein is a desirable characteristic, whether such an increase will be accompanied by enhanced protein quality is not known. Soybean protein quality could be significantly improved by increasing the concentration of the sulfur-containing amino acids, cysteine and methionine. To ascertain if a correlation existed between protein quantity and quality, a comparison of the amino acids of soybeans differing in protein content was made. Soybeans with higher protein content had a significantly lower percentage of sulfur amino acids, while those with lower protein exhibited a higher content of cysteine and methionine. Nitrogen application elevated the protein content but lowered that of the sulfur amino acids. Transmission electron microscopy examination of thin sections of low protein soybean seeds revealed several protein storage vacuoles that were partially filled with storage proteins. Fluorescence two-dimensional difference gel electrophoresis of soybean seed proteins revealed that nitrogen application favored the accumulation of the beta-subunit of beta-conglycinin while decreasing the accumulation of Bowman-Birk protease inhibitor (BBI), a protein rich in cysteine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 60% 2-propanol-extracted proteins showed a drastic reduction in the accumulation of BBI with increasing protein content. Northern blot analysis indicated that nitrogen had a negative influence on the expression of the BBI gene. Our results indicate that the negative correlation between total protein and sulfur amino acid content is mostly mediated by the differential accumulation of BBI. PMID:16076117

  6. Characterization of enzymatic saccharification for acid-pretreated lignocellulosic materials with different lignin composition

    Microsoft Academic Search

    Gia-Luen Guo; Deng-Chieh Hsu; Wen-Hua Chen; Wei-Hsi Chen; Wen-Song Hwang

    2009-01-01

    The enzymatic saccharification of three different feedstocks, rice straw, bagasse and silvergrass, which had been pretreated with different dilute acid concentrations, was studied to verify how enzymatic saccharification was affected by the lignin composition of the raw materials. There was a quantitatively inverse correlation between lignin content and enzymatic digestibility after pretreatment with 1%, 2% and 4% sulfuric acid. The

  7. Effect of sulfuric and phosphoric acid pretreatments on enzymatic hydrolysis of corn stover

    Microsoft Academic Search

    Byung-Hwan Um; M. Nazmul Karim; Linda L. Henk

    2003-01-01

    The pretreatment of corn stover with H2SO4 and H3PO4 was investigated. Pretreatments were carried out from 30 to 120 min in a batch reactor at 121°C, with acid concentrations\\u000a ranging from 0 to 2% (w\\/v) at a solid concentration of 5% (w\\/v). Pretreated corn stover was washed with distilled water until\\u000a the filtrate was adjusted to pH 7.0, followed by

  8. Effects of sulfur containing amino acids on iron and nitric oxide stimulated catecholamine oxidation

    Microsoft Academic Search

    M. Biasetti; R. Dawson Jr.

    2002-01-01

    Summary.  ?Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and\\u000a its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric\\u000a chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined\\u000a for their actions to stimulate quinone

  9. Production of lube oils by sulfuric acid treatment using a demulsifier

    Microsoft Academic Search

    N. M. Litvinova; É. K. Gabdusheva; A. M. Granat; N. M. Dolganova

    1987-01-01

    The effectiveness of demulsifiers in reducing wastewater output and contamination during the production of low viscosity industrial oils I-5A and I-8A was studied. The demulsifier Progalit was added to the acid oils during the neutralizing process. Reductions in the use of sodium hydroxide were established. Washwater quantity in the production of I-5A was reduced from six to two tons and

  10. Microbial cycling of iron and sulfur in acidic coal mining lake sediments

    Microsoft Academic Search

    Kirsten Küsel

    2003-01-01

    Lakes caused by coal mining processes are characterized by low pH, low nutrient status, and high concentrations of Fe(II) and sulfate due to the oxidation of pyrite in the surrounding mine tailings. Fe(III) produced during Fe(II) oxidation precipitates to the anoxic acidic sediment, where the microbial reduction of Fe(III) is the dominant electron-accepting process for the oxidation of organic matter,

  11. Aluminium alloys in sulfuric acid Part II: Aluminium-oxygen cells

    Microsoft Academic Search

    S. Müller; F. Holzer; J. Desilvestro; O. Haas

    1996-01-01

    Aluminium alloys were tested in Al\\/O2 cells with strongly acidic electrolytes containing minor amounts of chloride ions. The faradaic efficiency, the maximum discharge capacity and the peak power of various Al\\/O2 cells were evaluated. The temperature dependence of the faradaic efficiency was measured for an Al\\/O2 cell over the temperature range from 15 to 50°C. With a zinc-containing aluminium alloy,

  12. Cumulative Effect of Soil and Foliar Application of Nitrogen, Phosphorus, and Sulfur on Growth, Physico-Biochemical Parameters, Yield Attributes, and Fatty Acid Composition in Oil of Erucic Acid-Free Rapeseed-Mustard Genotypes

    Microsoft Academic Search

    Manzer H. Siddiqui; Firoz Mohammad; M. Nasir Khan; M. Masroor A. Khan

    2008-01-01

    The feasibility of split (soil + foliar) applications of nitrogen (N) and phosphorus (P) and addition of a small quantity of sulfur (S) in the spray was tested for improving performance of rapeseed-mustard genotypes in a factorial randomized field experiment. Three genotypes (two erucic acid free, viz. Brassica napus L. cv. ‘Hyola PAC – 401’ and Brassica juncea L. Czern.

  13. Benevolent behavior of Kleinia grandiflora leaf extract as a green corrosion inhibitor for mild steel in sulfuric acid solution

    NASA Astrophysics Data System (ADS)

    Pitchaipillai, Muthukrishnan; Raj, Karthik; Balasubramanian, Jeyaprabha; Periakaruppan, Prakash

    2014-11-01

    The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV-visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir's model, with a standard free energy of adsorption (? G ads) of -18.62 kJ/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.

  14. Production of lube oils by sulfuric acid treatment using a demulsifier

    SciTech Connect

    Litvinova, N.M.; Gabdusheva, E.K.; Granat, A.M.; Dolganova, N.M.

    1987-09-01

    The effectiveness of demulsifiers in reducing wastewater output and contamination during the production of low viscosity industrial oils I-5A and I-8A was studied. The demulsifier Progalit was added to the acid oils during the neutralizing process. Reductions in the use of sodium hydroxide were established. Washwater quantity in the production of I-5A was reduced from six to two tons and of I-8A from four to two tons for each ton of oil produced. The use of the demulsifier also shortened the production cycle and improved the quality of the wastewater.

  15. Chlorates induce pitting corrosion of iron in sulfuric acid solutions: An analysis based on current oscillations and a point defect model

    NASA Astrophysics Data System (ADS)

    Pagitsas, M.; Pavlidou, M.; Papadopoulou, S.; Sazou, D.

    2007-01-01

    Current oscillatory phenomena were used to investigate the effect of chlorates on the passive state of iron in sulfuric acid solutions. Experimental results show that chlorates cause pitting corrosion, besides general corrosion. It is shown that pitting is not due to the chlorate ion itself, but to chlorides produced via the reduction of chlorates by ferrous ions. General and pitting corrosion are explained in terms of a point defect model proposed to describe the oxide growth and breakdown.

  16. The synergistic inhibition between 8-hydroxyquinoline and chloride ion for the corrosion of cold rolled steel in 0.5 M sulfuric acid

    Microsoft Academic Search

    Libin Tang; Xueming Li; Yunsen Si; Guannan Mu; Guangheng Liu

    2006-01-01

    The corrosion inhibition of cold rolled steel in 0.5M sulfuric acid in the presence of 8-hydroxyquinoline and sodium chloride (NaCl) has been investigated by using weight loss and electrochemical techniques. The inhibition efficiency increases with increasing concentration of 8-hydroxyquinoline at the same temperature, but decreases with increasing temperature studied. A synergistic effect exists when 8-hydroxyquinoline and chloride ions are used

  17. The synergistic inhibition between hexadecyl trimethyl ammonium bromide (HTAB) and NaBr for the corrosion of cold rolled steel in 0.5 M sulfuric acid

    Microsoft Academic Search

    Libin Tang; Xueming Li; Guannan Mu; Guangheng Liu; Lin Li; Hongcheng Liu; Yunsen Si

    2006-01-01

    The synergistic effect of the mixture of hexadecyl trimethyl ammonium bromide (HTAB) and various concentrations of NaBr on\\u000a the corrosion of cold rolled steel in 0.5 M sulfuric acid has been investigated using weight loss method and polarization\\u000a method. The results reveal that the corrosion of cold rolled steel has been efficiently inhibited by HTAB in the presence\\u000a of NaBr in

  18. Mechanism of simulated solarlight-induced photocatalytic oxidation of 5-hydroxynaphthalene-1-sulphonic acid on sulfur doped TiO2

    Microsoft Academic Search

    Jiankun Ren; Guoqing Liu; Panying Peng; Yuping Wang

    2011-01-01

    The photodegradation of 5-hydroxynaphthalene-1-sulphonic acid (HNSA) was investigated with the TiO2 and sulfur doped TiO2 (S\\/TiO2) photocatalysts under the irradiation of the ultraviolet light (UV) and the simulated solar light. The S\\/TiO2 photocatalyst was found to be highly effective for the HNSA photodegradation both under the UV light or the simulated solar light irradiation. Especially, using various analysis methods, the

  19. Corrosion Behavior of Fe41Co7Cr15Mo14C15B6Y2 Bulk Metallic Glass in Sulfuric Acid Solutions

    NASA Astrophysics Data System (ADS)

    Fan, H. B.; Zheng, W.; Wang, G. Y.; Liaw, P. K.; Shen, J.

    2011-06-01

    An Fe41Co7Cr15Mo14C15B6Y2 bulk metallic glass with a diameter of 5 mm was prepared with the copper-mold-casting method. The corrosion resistance of this amorphous steel in sulfuric-acid solutions was determined by electrochemical measurements. The passive film formed on the surface of the alloy after immersion in the 0.5-mol/l H2SO4 solution for 1 week was analyzed by X-ray photoelectron spectroscopy (XPS). Electrochemical measurements show that the corrosion resistance of the amorphous steel in the 1 mol/l-H2SO4 solution is superior to a stainless steel (SUS 321), and is almost the same as Ti6Al4V, which shows that the amorphous steel has an excellent corrosion resistance in sulfuric-acid solutions. As the concentration of the sulfuric-acid solutions increases from 0.5 mol/l to 4 mol/l, the corrosion resistance of the amorphous steel decreases. The XPS result reveals that a bilayer structure of protective film formed on the surface of the amorphous steel in a H2SO4 solution. The compositions of the inner part of the film are MoO2, Cr2O3, CoO, and FeO, and those of the outer film are MoO3, Cr(OH)3, Co(OH)2, and Fe(OH)3.

  20. Dry deposition of sulfur dioxide and nitric acid to oak, elm and pine leaves

    SciTech Connect

    Dash, J.M. (General Motors Research Lab., Warren, MI (US))

    1988-01-01

    In this study, the deposition of SO{sub 2} and HNO{sub 3} was measured to three tree species, elm, oak and pine. Earlier work has shown that these three species cover of physical types (smooth oak leaves, rough elm leaves, and needles) and chemical types (acid and alkaline leaves) The total deposition is compared to the deposition measured through the stomata. After deposition, removal by revolatilization or extraction was determined. The data is used to estimate dry deposition fluxes of SO{sub 2} and HNO{sub 3} to forests that can then be combined with wet fluxes to determine total atmospheric inputs. Based on these results, a preliminary estimate is made of the possible detrimental effects to forests from atomspheric inputs.

  1. Rayleigh light scattering properties of atmospheric molecular clusters consisting of sulfuric acid and bases.

    PubMed

    Elm, Jonas; Norman, Patrick; Mikkelsen, Kurt V

    2015-06-28

    The Rayleigh light scattering properties of (H2SO4)a(NH3)b and (H2SO4)a((CH3)2NH)b atmospheric molecular clusters have been investigated using a response theory approach. Using density functional theory the molecular structures and stepwise formation free energies of clusters with a and b up to 4 have been re-investigated. The Rayleigh scattering intensities are calculated from the dipole polarizability tensor ? using the CAM-B3LYP functional by applying linear response methods. The intrinsic scattering properties of (H2SO4)a(NH3)b and (H2SO4)a((CH3)2NH)b indicate that amine containing clusters scatter light significantly more efficiently then their ammonia containing counterparts. Using the Atmospheric Cluster Dynamics Code (ACDC) the steady state cluster concentrations are estimated and the effective scattering is calculated. The effective scattering is shown to be highly dependent on the estimated concentrations and indicates that there exist competitive pathways, such as nucleation and coagulation, which influence the cluster distributions. The frequency dependence of the scattering is found to depend on the cluster composition and show increased responses when clusters contain more bases than acid molecules. Based on structures obtained using semi-empirical molecular dynamics simulations the Rayleigh scattering properties of clusters with up to 20 acid-base pairs are evaluated. This study represents the first step towards gaining a fundamental understanding of the scattering properties of small atmospheric clusters in the ambient atmosphere. PMID:25811805

  2. Design and initial operation of a high-solids, pilot-scale reactor for dilute-acid pretreatment of lignocellulosic biomass

    Microsoft Academic Search

    Teh-An Hsu; Mike Himmel; Dan Schell; Jody Farmer; Mark Berggren

    1996-01-01

    A recently installed 100-L horizontal shaft custom-fabricated mixer\\/reactor, made of Carpenter 20 Cb-3 stainless steel and\\u000a designed for high-solids, dilute-acid pretreatment of lignocellulosic biomass, is described. Several preliminary runs with\\u000a a hardwood and a herbaceous feedstock are reported; the results show the operation to be reliable with good reproducibility.\\u000a No significant differences between comparable pretreatments in the high-solids reactor and

  3. 40 CFR 721.9672 - Amides, tall-oil fatty, N-[2-[2-hydroxyethyl)amino]ethyl], reaction products with sulfur dioxide...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...reaction products with sulfur dioxide; fatty acids, tall-oil, reaction products with...1-piperazineethanamine and sulfur dioxide; fatty acids, tall-oil reaction products with sulfur...reaction products with sulfur dioxide; fatty acids, tall-oil, reaction products...

  4. 40 CFR 721.9672 - Amides, tall-oil fatty, N-[2-[2-hydroxyethyl)amino]ethyl], reaction products with sulfur dioxide...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...reaction products with sulfur dioxide; fatty acids, tall-oil, reaction products with...1-piperazineethanamine and sulfur dioxide; fatty acids, tall-oil reaction products with sulfur...reaction products with sulfur dioxide; fatty acids, tall-oil, reaction products...

  5. Production of nanocrystalline cellulose from an empty fruit bunches using sulfuric acid hydrolysis: Effect of reaction time on the molecular characteristics

    NASA Astrophysics Data System (ADS)

    Al-Dulaimi, Ahmed A.; R, Rohaizu; D, Wanrosli W.

    2015-06-01

    Nanocrystalline cellulose (NCC) was isolated from OPEFB pulp via sulfuric acid hydrolysis. The influence of reaction time to the molecular weight and surface charge of the NCC was investigated. Characterization of the product was carried out using zeta potential measurement and gel permeation chromatography test. Zeta potential measurement showed that the surface negative charge significantly increases with increasing reaction time. Gel permeation chromatography test indicates that molecular weight of NCC change variably with increasing of hydrolysis time. (Keywords: Nanocrystalline cellulose; acid hydrolysis; sulfate content; molecular weight)

  6. oxidation of americium(iii) and the stability of americium(iv) and americium(vi) in solutions of sulfuric and perchloric acids

    SciTech Connect

    Milyukova, M.S.; Litvina, M.N.; Myasoedov, B.F.

    1986-07-01

    The oxidation of weighable amounts of americium in solutionsof sulfuric and perchloric acids was investigated by a spectrophotometric method. The stability of americium(IV) and (VI) in mineral acids was studied. A method was developed for the production of tetravalent americium in solutions of 0.1-3 M H/sub 2/SO/sub 4/ and 0.1-1 M HClO/sub 4/, containing potassium phosphotungstate K/sub 10/P/sub 2/W/sub 17/O/sub 61/ an an oxidizing mixture - a silver salt and ammonium persulfate.

  7. Structural modeling of djenkolic acid with sulfur replaced by selenium and tellurium.

    PubMed

    Melnikov, Petr; Nascimento, Valter A; Silva, Anderson F; Consolo, Lourdes Z Z

    2014-01-01

    The comparative structural modeling of djenkolic acid and its derivatives containing selenium and tellurium in chalcogen sites (Ch=Se, Te) has provided detailed information about the bond lengths and bond angles, filling the gap in what we know about the structural characteristics of these aminoacids. The investigation using the molecular mechanics technique with good approximation confirmed the available information on X-ray refinements for the related compounds methionine and selenomethionine, as well as for an estimate made earlier for telluromethionine. It was shown that the Ch-C(3) and Ch-C(4) bond lengths grow in parallel with the increasing anionic radii. Although the distances C-C, C-O, and C-N are very similar, the geometry of conformers is quite different owing to the possibility of rotation about four carbon atoms, hence the remarkable variability observed in dihedral angles. It was shown that the compounds contain a rigid block with two Ch atoms connected through a methylene group. The standard program Gaussian 03 with graphical interface Gaussview 4.1.2 has proved to be satisfactory tool for the structural description of less-common bioactive compositions when direct X-ray results are absent. PMID:24747644

  8. Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

    PubMed

    Hilty, Florentine M; Knijnenburg, Jesper T N; Teleki, Alexandra; Krumeich, Frank; Hurrell, Richard F; Pratsinis, Sotiris E; Zimmermann, Michael B

    2011-01-01

    Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe color changes than FeSO(4) when added to difficult-to-fortify foods. PMID:21535701

  9. Postprandial Cysteine/Cystine Redox Potential in Human Plasma Varies with Meal Content of Sulfur Amino Acids1–3

    PubMed Central

    Park, Youngja; Ziegler, Thomas R.; Gletsu-Miller, Nana; Liang, Yongliang; Yu, Tianwei; Accardi, Carolyn Jonas; Jones, Dean P.

    2010-01-01

    Few data are available on plasma redox responses to sulfur amino acid (SAA) loads. In this study, we had 2 aims: to determine whether the SAA content of a meal affected postprandial plasma cysteine (Cys), cystine (CySS), or redox potential (EhCySS) in humans and whether SAA intake level (adequate or inadequate) in the days preceding the meal challenge affected these postprandial levels. Eight healthy individuals aged 18–36 y were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (inadequate SAA) and then fed isoenergetic, isonitrogenous meals with adequate SAA for 5 d. On the first and last days with the chemically defined meals, a morning meal containing 60% of the daily food intake was given, and plasma Cys, CySS, and EhCySS were determined over an 8-h postprandial time course. Following equilibration to adequate intake, provision of the meal with SAA resulted in increased plasma Cys and CySS concentrations and more reduced plasma EhCySS compared with the postprandial values following the same meal without SAA. Equilibration to inadequate SAA intake for the days preceding the meal challenge did not affect this response. The magnitude of the difference in postprandial plasma EhCySS (10 mV) due to meal content of SAA was comparable to those which alter physiologic signaling and/or are associated with disease risk. Consequently, the SAA content of meals could affect physiologic signaling and associated disease mechanisms in the postprandial period by changes in Cys, CySS, or EhCySS. PMID:20164364

  10. Heterogeneous Interactions of ClONO2 and HCl with Sulfuric Acid Tetrahydrate: Implications for the Stratosphere

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Jayne, John T.; Molina, Mario J.

    1994-01-01

    The reaction probabilities for ClONO2+H2O- HOCl + HNO3 and ClONO2+ HCl Cl2 +HNO3 have been investigated on sulfuric acid tetrahydrate (SAT, H2SO4-4H2O)surfaces at temperatures between 190 and 230 K and at reactant concentrations that are typical in the lower stratosphere, using a fast-flow reactor coupled to a quadrupole mass spectrometer. The results indicate that the reaction probabilities as well as HCl uptake depend strongly on the thermodynamic state of SAT surface: they decrease significantly with decreasing H2O partial pressure at a given temperature, and decrease with increasing temperature at a given H2O partial pressure, as the SAT changes from the H2O-rich form to the H2SO4-rich form. For H2O-rich SAT at 195 K gamma(sub 1) approx. = -0.01 and gamma(sub 2) greater or equal to 0.1, whereas the values for H2SO4-rich SAT decrease by more than 2 orders of magnitude. At low concentrations of HCl, close to those found in the stratosphere, the amount of HCl taken up by H2O-rich SAT films corresponds to a coverage of the order of a tenth of a monolayer (approx. = 10(exp 14) molecules/sq cm); H2SO4-rich SAT films take up 2 orders of magnitude less HCl (les than 10(exp 12) molecules/sq cm). Substantial HCl uptake at high HCl concentrations is also observed, as a result of surface melting. The data reveal that frozen stratospheric sulfate aerosols may play an important role in chlorine activation in the winter polar stratosphere via processes similar to those occurring on the surfaces of polar stratospheric cloud particles.

  11. [Determination of nine hazardous elements in textiles by inductively coupled plasma optical emission spectrometer after microwave-assisted dilute nitric acid extraction].

    PubMed

    Chen, Fei; Xu, Dian-dou; Tang, Xiao-ping; Cao, Jing; Liu, Ya-ting; Deng, Jian

    2012-01-01

    Textiles are easily contaminated by heavy metals in the course of processing. In order to monitor the quality of textiles, a new method was developed for simultaneous determination of arsenic, antimony, lead, cadmium, chromium, cobalt, copper, nickel and mercury in textiles by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted dilute nitric acid extraction. After optimizing extraction conditions, we ultimately selected 5% nitric acid as extractant and 5 min as extraction time with the extraction temperature of 120 degrees C and instrument power of 400W in the microwave-assisted extraction procedure. Nine hazardous elements were detected sequentially by ICP-OES. The results showed that the detection limits were 0.3-15 microg x L(-1) and the recoveries 73.6%-105% with the RSDs (n = 3) of 0.1%-3%. The proposed method was successfully used to determine nine elements in cotton, wool, terylene and acrylic. PMID:22497167

  12. Quantitative detection of trichloroacetic acid in human urine using isotope dilution high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Kuklenyik, Zsuzsanna; Ashley, David L; Calafat, Antonia M

    2002-05-01

    The chemical disinfection of drinking water to control microbial contaminants results in the formation of disinfection byproducts (DBPs). The volatile trihalomethanes and the nonvolatile haloacetic acids (HAAs) are the most prevalent DBPs. It is important to monitor human exposure to HAAs because of their potential adversehealth effects, such as cancer. Among the HAAs, urinary trichloroacetic acid (TCAA) is a potential valid biomarker for assessing chronic ingestion exposure to HAAs from drinking water. We have developed a rugged, high-throughput, sensitive, accurate, and precise assay for the measurement of trace levels of TCAA in human urine using a simple solid-phase extraction (SPE) cleanup followed by isotope dilution high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). TCAA is extracted from the urine using SPE, separated from other extract components by reversed-phase HPLC, and analyzed by negative ion electrospray ionization-isotope dilution-MS/MS using a multiple reaction monitoring experiment. The method is simple and fast and is not labor intensive (sample preparation and analysis can be performed in approximately 15 min) with a limit of detection of 0.5 ng/mL in 1 mL of urine. PMID:12033307

  13. Effectiveness of the bran media and bacteria inoculum treatments in increasing pH and reducing sulfur-total of acid sulfate soils

    NASA Astrophysics Data System (ADS)

    Taufieq, Nur Anny Suryaningsih; Rahim, Sahibin Abdul; Jamil, Habibah

    2013-11-01

    This study was carried out to determine the effectiveness ofsulfate reducing bacteria (SRB) in using bran as a source of food and energy, and to see the effectiveness of the bran media and bacteria inoculums treatments for pH and sulfur-total of acid sulfate reduction insoils. This study used two factors in group random designs with four treatments for bacteria inoculum of B1 (1%), B2 (5%), B3 (10%), B4 (15%) and two treatments for organic media (bran) of D1 (1:1) and D2 (1:19). Based on three replications, the combination resulted in a total of 24 treatments. Soil pH was measured using the Duddridge and Wainright method and determination of sulfate content in soil was conducted by the spectrophotometry method. The data obtained was analyzed for significance by Analysis of Variance and the Least Significant Difference Test. The pH of the initial acid sulfate soils ranged from 3 to 4 and the soil sulfur-total ranged from 1.4% to 10%. After mixing sulfate reducing bacteria with the bran mediaand incubated for four days, the pH of the acid sulfate soils increased from 3.67 to 4.20, while the soil sulfur-total contents had been reduced by 2.85% to 0.35%. This experiment has proven that an acid sulfate soil with low pH is a good growth medium for the sulfate reducing bacteria. The bestincubation period to achieve an effective bioremediation resultthrough sulfate percentage reduction by sulfate reducing bacteria was 10 days, while the optimum bran media dose was 1:19, and the bacteria inoculums dose was 10%.

  14. The formation of acid rain in the atmosphere, adjacent to the TTP with the joint-condensing of sulfur dioxide and water vapor

    NASA Astrophysics Data System (ADS)

    Gvozdyakov, D. V.; Gubin, V. E.; Matveeva, A. A.

    2014-08-01

    Presents the results of mathematical simulation of the condensation process of sulphur dioxide and water vapor on the condensation nuclei surface under the action of natural factors. Numerical investigations were carried out for the summer at a moderate speed of the wind. The influence of the parameter of condensation on the speed of the process of sulfuric acid drops formation in the air space was analyzed. Time ranges, sufficient for the formation of the acid rain sedimentation in the atmosphere, adjacent to the areas of thermal power station work were established. It is shown that the speed of air masses movement effects on the process of acid anthropogenic admixtures dispersion in the atmosphere. Approbation of the obtained results was carried out by checking the difference scheme conservative and solution of test problems.

  15. Quantitative analysis of N-phenylpropenoyl-L-amino acids in roasted coffee and cocoa powder by means of a stable isotope dilution assay.

    PubMed

    Stark, Timo; Justus, Helene; Hofmann, Thomas

    2006-04-19

    Since recent reports on the role of N-phenylpropenoyl-L-amino acids as powerful antioxidants and key contributors to the astringent taste of cocoa nibs, there is an increasing interest in the concentrations of these phytochemicals in plant-derived foods. A versatile analytical method for the accurate quantitative analysis of N-phenylpropenoyl-L-amino acids in plant-derived foods by means of HPLC-MS/MS and synthetic stable isotope labeled N-phenylpropenoyl-L-amino acids as internal standards was developed. By means of the developed stable isotope dilution assay (SIDA), showing recovery rates of 95-102%, 14 N-phenylpropenoyl-L-amino acids were quantified for the first time in cocoa and coffee samples. On the basis of the results of LC-MS/MS experiments as well as cochromatography with the synthetic reference compounds N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan, N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan, and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine, respectively, were detected for the first time in cocoa powder, and (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-tyrosine, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tyrosine, (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid, (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid, N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tryptophan, N-[4'-hydroxy-(E)-cinnamoyl]-L-tryptophan, and N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-tryptophan, respectively, were detected for the first time in coffee beverages. PMID:16608201

  16. Chemiluminescence by the interaction of XeO{sub 3} and the products of photolysis of uranyl solutions in sulfuric acid

    SciTech Connect

    Khamidullina, L.A.; Lotnik, S.V.; Kazakov, V.P. [Institute of Organic Chemistry, Ufa (Russian Federation)

    1994-10-01

    Using the chemiluminescence oxidation of U(IV) and H{sub 2}O{sub 2} with xenon trioxide as a model, it has been found that during the photolysis of solutions of UO{sub 2}SO{sub 4} in sulfuric acid in the absence of any organic compounds, the accumulation of U(SO{sub 4}){sub 2} and H{sub 2}O{sub 2} takes place as a result of the reaction of the primary products of the photoreduction of uranyl ion, i.e., UO{sub 2}{sup +} and the OH radical.

  17. An investigation of the reactions of butylene and isobutane in the presence of concentrated sulfuric acid using a wetted wall reactor 

    E-print Network

    Howerton, Murlin T.

    1949-01-01

    alkylation reaction between iso? butane and butylene in the presence of concentrated sulfuric acid. The net result of the principal reaction involved is the combination of equal moles of the olefin and isobutane to form octanes. Numerous in? vestigations... is shown in Figure I* Feed stocks of isobutane and butylene were obtained 8 S <0 s ? I 1 ? 5! * k I cj 5 o Q?j 9 from hydrocarbon cylinders fitted with pressure reducing valves having a constant discharge pressure. The two feed stocks were...

  18. SPECIFICITY OF CYSTEINE SULFINATE DECARBOXYLASE (CSD) FOR SULFUR-CONTAINING AMINO-ACIDS * * Part of this work was presented at the last meeting on ‘Taurine in health and disease’ (1993) held in Cologne (Germany)

    Microsoft Academic Search

    K. Q. DO; M. L. TAPPAZ

    1996-01-01

    Cysteine sulfinate decarboxylase (CSD) which decarboxylates cysteine sulfinic acid (CSA) to form hypotaurine is thought to be involved in the biosynthesis of taurine. It was recently localized in astrocytes in the cerebellum and hippocampus by immunocytochemistry. Another sulfur-containing aminoacid (SCAA), homocysteic acid (HCA), was also found in astrocytes in these regions. We therefore investigated the specificity of CSD vs CSA

  19. Performance and techno-economic assessment of several solid-liquid separation technologies for processing dilute-acid pretreated corn stover.

    PubMed

    Sievers, David A; Tao, Ling; Schell, Daniel J

    2014-09-01

    Solid-liquid separation of pretreated lignocellulosic biomass slurries is a critical unit operation employed in several different processes for production of fuels and chemicals. An effective separation process achieves good recovery of solute (sugars) and efficient dewatering of the biomass slurry. Dilute acid pretreated corn stover slurries were subjected to pressure and vacuum filtration and basket centrifugation to evaluate the technical and economic merits of these technologies. Experimental performance results were used to perform detailed process simulations and economic analysis using a 2000 tonne/day biorefinery model to determine differences between the various filtration methods and their process settings. The filtration processes were able to successfully separate pretreated slurries into liquor and solid fractions with estimated sugar recoveries of at least 95% using a cake washing process. A continuous vacuum belt filter produced the most favorable process economics. PMID:24995879

  20. Use of Gelidium amansii as a promising resource for bioethanol: a practical approach for continuous dilute-acid hydrolysis and fermentation.

    PubMed

    Park, Jeong-Hoon; Hong, Ji-Yeon; Jang, Hyun Chul; Oh, Seung Geun; Kim, Sang-Hyoun; Yoon, Jeong-Jun; Kim, Yong Jin

    2012-03-01

    A facile continuous method for dilute-acid hydrolysis of the representative red seaweed species, Gelidium amansii was developed and its hydrolysate was subsequently evaluated for fermentability. In the hydrolysis step, the hydrolysates obtained from a batch reactor and a continuous reactor were systematically compared based on fermentable sugar yield and inhibitor formation. There are many advantages to the continuous hydrolysis process. For example, the low melting point of the agar component in G. amansii facilitates improved raw material fluidity in the continuous reactor. In addition, the hydrolysate obtained from the continuous process delivered a high sugar and low inhibitor concentration, thereby leading to both high yield and high final ethanol titer in the fermentation process. PMID:22261657

  1. Effect of mechanical disruption on the effectiveness of three reactors used for dilute acid pretreatment of corn stover Part 1: chemical and physical substrate analysis

    PubMed Central

    2014-01-01

    Background There is considerable interest in the conversion of lignocellulosic biomass to liquid fuels to provide substitutes for fossil fuels. Pretreatments, conducted to reduce biomass recalcitrance, usually remove at least some of the hemicellulose and/or lignin in cell walls. The hypothesis that led to this research was that reactor type could have a profound effect on the properties of pretreated materials and impact subsequent cellulose hydrolysis. Results Corn stover was dilute-acid pretreated using commercially relevant reactor types (ZipperClave® (ZC), Steam Gun (SG) and Horizontal Screw (HS)) under the same nominal conditions. Samples produced in the SG and HS achieved much higher cellulose digestibilities (88% and 95%, respectively), compared to the ZC sample (68%). Characterization, by chemical, physical, spectroscopic and electron microscopy methods, was used to gain an understanding of the effects causing the digestibility differences. Chemical differences were small; however, particle size differences appeared significant. Sum-frequency generation vibrational spectra indicated larger inter-fibrillar spacing or randomization of cellulose microfibrils in the HS sample. Simons’ staining indicated increased cellulose accessibility for the SG and HS samples. Electron microscopy showed that the SG and HS samples were more porous and fibrillated because of mechanical grinding and explosive depressurization occurring with these two reactors. These structural changes most likely permitted increased cellulose accessibility to enzymes, enhancing saccharification. Conclusions Dilute-acid pretreatment of corn stover using three different reactors under the same nominal conditions gave samples with very different digestibilities, although chemical differences in the pretreated substrates were small. The results of the physical and chemical analyses of the samples indicate that the explosive depressurization and mechanical grinding with these reactors increased enzyme accessibility. Pretreatment reactors using physical force to disrupt cell walls increase the effectiveness of the pretreatment process. PMID:24713111

  2. Determination of Glyphosate, its Degradation Product Aminomethylphosphonic Acid, and Glufosinate, in Water by Isotope Dilution and Online Solid-Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry

    USGS Publications Warehouse

    Meyer, Michael T.; Loftin, Keith A.; Lee, Edward A.; Hinshaw, Gary H.; Dietze, Julie E.; Scribner, Elisabeth A.

    2009-01-01

    The U.S. Geological Survey method (0-2141-09) presented is approved for the determination of glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate in water. It was was validated to demonstrate the method detection levels (MDL), compare isotope dilution to standard addition, and evaluate method and compound stability. The original method USGS analytical method 0-2136-01 was developed using liquid chromatography/mass spectrometry and quantitation by standard addition. Lower method detection levels and increased specificity were achieved in the modified method, 0-2141-09, by using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The use of isotope dilution for glyphosate and AMPA and pseudo isotope dilution of glufosinate in place of standard addition was evaluated. Stable-isotope labeled AMPA and glyphosate were used as the isotope dilution standards. In addition, the stability of glyphosate and AMPA was studied in raw filtered and derivatized water samples. The stable-isotope labeled glyphosate and AMPA standards were added to each water sample and the samples then derivatized with 9-fluorenylmethylchloroformate. After derivatization, samples were concentrated using automated online solid-phase extraction (SPE) followed by elution in-line with the LC mobile phase; the compounds separated and then were analyzed by LC/MS/MS using electrospray ionization in negative-ion mode with multiple-reaction monitoring. The deprotonated derivatized parent molecule and two daughter-ion transition pairs were identified and optimized for glyphosate, AMPA, glufosinate, and the glyphosate and AMPA stable-isotope labeled internal standards. Quantitative comparison between standard addition and isotope dilution was conducted using 473 samples analyzed between April 2004 and June 2006. The mean percent difference and relative standard deviation between the two quantitation methods was 7.6 plus or minus 6.30 (n = 179), AMPA 9.6 plus or minus 8.35 (n = 206), and glufosinate 9.3 plus or minus 9.16 (n = 16). The analytical variation of the method, comparison of quantitation by isotope dilution and multipoint linear regressed standard curves, and method detection levels were evaluated by analyzing six sets of distilled-water, groundwater, and surface-water samples spiked in duplicate at 0.0, 0.05, 0.10 and 0.50 microgram per liter and analyzed on 6 different days during 1 month. The grand means of the normalized concentration percentage recovery for glyphosate, AMPA, and glufosinate among all three matrices and spiked concentrations ranged from 99 to 114 plus or minus 2 to 7 percent of the expected spiked concentration. The grand mean of the percentage difference between concentrations calculated by standard addition and linear regressed multipoint standard curves ranged from 8 to 15 plus or minus 2 to 9 percent for the three compounds. The method reporting levels calculated from all the 0.05- microgram per liter spiked samples were 0.02 microgram per liter for all three compounds. Compound stability experiments were conducted on 10 samples derivatized four times for periods between 136 to 269 days. The glyphosate and AMPA concentrations remained relatively constant in samples held up to 136 days before derivatization. The half life of glyphosate varied from 169 to 223 days in the underivatized samples. Derivatized samples were analyzed the day after derivitization, and again 54 and 64 days after derivatization. The derivatized samples analyzed at days 52 and 64 were within 20 percent of the concentrations of the derivatized samples analyzed the day after derivatization.

  3. Growth requirements of hyperthermophilic sulfur-dependent heterotrophic archaea isolated from a shallow submarine geothermal system with reference to their essential amino acids.

    PubMed Central

    Hoaki, T; Nishijima, M; Kato, M; Adachi, K; Mizobuchi, S; Hanzawa, N; Maruyama, T

    1994-01-01

    Three hyperthermophilic sulfur-dependent heterotrophs were isolated from a shallow submarine hydrothermal system at an inlet of Kodakara-jima island, Kagoshima, Japan. The isolates grew at 60 to 97 degrees C, with the optimum temperatures at 85 to 90 degrees C. Sensitivity to rifampin and the existence of ether lipids indicated that the isolates are hyperthermophilic archaea. Partial sequencing of the genes coding for 16S rRNA showed that the three isolates are closely related to the genus Thermococcus. They grew on proteinaceous mixtures, such as yeast extract, Casamino Acids, and purified proteins (e.g., casein and gelatin), but not on carbohydrates or organic acids as sole carbon and energy sources. Nine amino acids were essential for growth of isolate KS-1 (Thr, Leu, Ile, Val, Met, Phe, His, Tyr, and Arg). Isolate KS-2 required Lys in addition to the nine amino acids, and KS-8 required Lys instead of Tyr. In comparative studies, it was shown that Thermococcus celer DSM 2476 required 10 amino acids (Thr, Leu, Ile, Val, Met, Phe, Tyr, Trp, Lys, and Arg) while Pyrococcus furiosus DSM 3638 required only Ile and Val. The hyperthermophilic fermentative eubacterium Thermotoga neapolitana DSM 4359 did not require any amino acids for growth. Images PMID:8085828

  4. SULFUR ASSIMILATION IN PLANTS AND WEED CONTROL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sulfur is an indispensable element for plants. It is found in sulfur-containing amino acids, cysteine and methionine, and in various other important biochemical components and processes. Inhibitors of sulfur assimilation, or cysteine and methionine synthesis, could be potential herbicides. The sulf...

  5. CONTROLLING SULFUR OXIDES

    EPA Science Inventory

    This Research Summary describes EPA's program to develop new and improve existing technologies for sulfur oxides control. As we increasingly turn to coal as the primary utility and industrial fuel, while trying to deal with the problems of acid precipitation, visibility degradati...

  6. Isotope-dilution assay for urinary methylmalonic acid in the diagnosis of vitamin B12 deficiency. A prospective clinical evaluation

    SciTech Connect

    Matchar, D.B.; Feussner, J.R.; Millington, D.S.; Wilkinson, R.H. Jr.; Watson, D.J.; Gale, D.

    1987-05-01

    Vitamin B12 deficiency is a frequently considered diagnosis for which there is no single, commonly available and accurate test. A urinary methylmalonic acid assay using gas chromatography-mass spectrometry has been proposed as the preferred test. We reviewed vitamin B12 assays on 1599 consecutive patients and prospectively studied all patients with low serum B12 levels (n = 75) and a random sample of patients with normal levels (n = 68). Of 96 evaluable patients, 7 had clinical deficiency. All 7 deficient patients had urinary methylmalonic acid levels greater than 5 micrograms/mg creatine (sensitivity, 100%; confidence interval, 65% to 100%). Of the 89 patients who were not clinically deficient, 88 had urinary methylmalonic acid levels less than or equal to 5 micrograms/mg creatinine (specificity, 99%). The overall test accuracy in this population was 99%. If the high sensitivity and specificity of the gas chromatography-mass spectrometry assay for urinary methylmalonic acid is supported by other clinical studies, the methylmalonic acid assay may become the reference standard for the diagnosis of vitamin B12 deficiency.

  7. /sup 18/O-isotope effect in /sup 13/C nuclear magnetic resonance spectroscopy. 4. Oxygen exchange of (1-/sup 13/C, /sup 18/O/sub 2/)acetic acid in dilute acid

    SciTech Connect

    Risley, J.M.; Van Etten, R.L.

    1981-07-29

    The /sup 18/O-iosotope shift in /sup 13/C NMR spectroscopy is shown to provide a widely applicable technique for studying the kinetics of oxygen exchange reactions in a nearly continuous assay mode. Here, the technique is used to study the acid-catalyzed medium carboxyl(oxygen)-water exchange reaction of (1-/sup 13/C, /sup 18/O/sub 2/)acetic acid at 32/sup 0/C. The /sup 18/O-isotope-induced shift fo the /sup 13/C NMR signal of the /sup 13/C-enriched carboxyl carbon in acetic acid permits a facile and direct measurement of the relative concentrations of the three (oxygen) isotopic species of acetic acid. The pseudo-first-order rate constant is evaluated as a function of pH and added salt for the salts sodium chloride and sodium perchlorate. The pH profile is typical of those observed for related acid-catalyzed oxygen exchange reactions of the carboxyl group. In the dilute-acid region the rate is approximately first order in hydrogen ion. The present results definitively establish the salt effect on the exchange reaction, resolving a conflict between earlier reports. The rate of the exchange reaction is decreased by increasing concentrations of the two salts. The magnitude of the rate decrease depends on he nature as well as the concentration of the salt. Possible interpretations of the results are discussed.

  8. A rotating ring–disk study of the initial stages of the anodic dissolution of chalcopyrite in acidic solutions

    Microsoft Academic Search

    I. Lazaro; M. J. Nicol

    2006-01-01

    The initial stages of the dissolution of chalcopyrite have been studied using rotating ring–disk electrode techniques in dilute\\u000a sulfuric acid solutions at 60 °C. It has been confirmed that the mineral undergoes a dissolution process under freely dissolving\\u000a conditions in the absence of an oxidant. This process involves the formation of soluble copper(II) ions and a soluble sulfur\\u000a species which is

  9. Project for laboratory study for removal of organic sulfur from coal

    SciTech Connect

    Not Available

    1981-01-15

    Major accomplishments are listed: 1. It was found that molten sodium hydroxide (in place of mixed sodium and potassium hydroxides) followed by dilute sulfuric acid wash gave Gravimelt coal with the usual amount of sulfur and mineral matter removal but there was no MAF heat content loss over the small amount required for replacement of sulfur atoms by oxygen atoms in the coal structure - e.g., these samples had both measured heat content and MAF heat content in excess of 1400 Btu/lb. Therefore, the selectivity of the Gravimelt Process appears to be very high. 2. It was found that demineralized and desulfurizd Gravimelt coal has significantly less alkali metals content than the input coal. 3. Kentucky No. 11 coal was reduced in sulfur content to a level of 0.10 lbs of sulfur (0.20 lbs of sulfur dioxide)/10/sup 6/ Btu with an ash content of 0.21% in a cumulative reaction time of 60 minutes. This represents a 96% reduction in sulfur and a 97% reduction in ash. This product is significantly lower in sulfur content and ash than are typical synthetic or conventional liquid boiler fuels. 4. The Gravimelt Process was tested on Illinois No. 6 coal giving essentially identical results to those previously obtained for the Kentucky No. 11 coal under the same conditions (89% reduction in sulfur and 97% reduction in ash). 5. A technology for the regeneration of spent caustic has been identified within the tanning industry which corresponds to most of our Gravimelt Process requirements.

  10. Chemical composition and response to dilute-acid pretreatment and enzymatic saccharification of alfalfa, reed canarygrass, and switchgrass

    Microsoft Academic Search

    Bruce S. Dien; Hans-Joachim G. Jung; Kenneth P. Vogel; Michael D. Casler; JoAnn F. S. Lamb; Loren Iten; Robert B. Mitchell; Gautum Sarath

    Alfalfa stems, reed canarygrass, and switchgrass; perennial herbaceous species that have potential as biomass energy crops in temperate regions; were evaluated for their bioconversion potential as energy crops. Each forage species was harvested at two or three maturity stages and analyzed for carbohydrates, lignin, protein, lipid, organic acids, and mineral composition. The biomass samples were also evaluated for sugar yields

  11. Lunar sulfur

    NASA Technical Reports Server (NTRS)

    Kuck, David L.

    1991-01-01

    Ideas introduced by Vaniman, Pettit and Heiken in their 1988 Uses of Lunar Sulfur are expanded. Particular attention is given to uses of SO2 as a mineral-dressing fluid. Also introduced is the concept of using sulfide-based concrete as an alternative to the sulfur-based concretes proposed by Leonard and Johnson. Sulfur is abundant in high-Ti mare basalts, which range from 0.16 to 0.27 pct. by weight. Terrestrial basalts with 0.15 pct. S are rare. For oxygen recovery, sulfur must be driven off with other volatiles from ilmenite concentrates, before reduction. Troilite (FeS) may be oxidized to magnetite (Fe3O4) and SO2 gas, by burning concentrates in oxygen within a magnetic field, to further oxidize ilmenite before regrinding the magnetic reconcentration. SO2 is liquid at -20 C, the mean temperature underground on the Moon, at a minimum of 0.6 atm pressure. By using liquid SO2 as a mineral dressing fluid, all the techniques of terrestrial mineral separation become available for lunar ores and concentrates. Combination of sulfur and iron in an exothermic reaction, to form iron sulfides, may be used to cement grains of other minerals into an anhydrous iron-sulfide concrete. A sulfur-iron-aggregate mixture may be heated to the ignition temperature of iron with sulfur to make a concrete shape. The best iron, sulfur, and aggregate ratios need to be experimentally established. The iron and sulfur will be by-products of oxygen production from lunar minerals.

  12. Lunar sulfur

    NASA Astrophysics Data System (ADS)

    Kuck, David L.

    Ideas introduced by Vaniman, Pettit and Heiken in their 1988 Uses of Lunar Sulfur are expanded. Particular attention is given to uses of SO2 as a mineral-dressing fluid. Also introduced is the concept of using sulfide-based concrete as an alternative to the sulfur-based concretes proposed by Leonard and Johnson. Sulfur is abundant in high-Ti mare basalts, which range from 0.16 to 0.27 pct. by weight. Terrestrial basalts with 0.15 pct. S are rare. For oxygen recovery, sulfur must be driven off with other volatiles from ilmenite concentrates, before reduction. Troilite (FeS) may be oxidized to magnetite (Fe3O4) and SO2 gas, by burning concentrates in oxygen within a magnetic field, to further oxidize ilmenite before regrinding the magnetic reconcentration. SO2 is liquid at -20 C, the mean temperature underground on the Moon, at a minimum of 0.6 atm pressure. By using liquid SO2 as a mineral dressing fluid, all the techniques of terrestrial mineral separation become available for lunar ores and concentrates. Combination of sulfur and iron in an exothermic reaction, to form iron sulfides, may be used to cement grains of other minerals into an anhydrous iron-sulfide concrete. A sulfur-iron-aggregate mixture may be heated to the ignition temperature of iron with sulfur to make a concrete shape. The best iron, sulfur, and aggregate ratios need to be experimentally established. The iron and sulfur will be by-products of oxygen production from lunar minerals.

  13. Improved ethanol yield and reduced Minimum Ethanol Selling Price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 1) Experimental

    PubMed Central

    2012-01-01

    Background Historically, acid pretreatment technology for the production of bio-ethanol from corn stover has required severe conditions to overcome biomass recalcitrance. However, the high usage of acid and steam at severe pretreatment conditions hinders the economic feasibility of the ethanol production from biomass. In addition, the amount of acetate and furfural produced during harsh pretreatment is in the range that strongly inhibits cell growth and impedes ethanol fermentation. The current work addresses these issues through pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. Results The results showed that deacetylation with 0.1 M NaOH before acid pretreatment improved the monomeric xylose yield in pretreatment by up to 20% while keeping the furfural yield under 2%. Deacetylation also improved the glucose yield by 10% and the xylose yield by 20% during low solids enzymatic hydrolysis. Mechanical refining using a PFI mill further improved sugar yields during both low- and high-solids enzymatic hydrolysis. Mechanical refining also allowed enzyme loadings to be reduced while maintaining high yields. Deacetylation and mechanical refining are shown to assist in achieving 90% cellulose yield in high-solids (20%) enzymatic hydrolysis. When fermentations were performed under pH control to evaluate the effect of deacetylation and mechanical refining on the ethanol yields, glucose and xylose utilizations over 90% and ethanol yields over 90% were achieved. Overall ethanol yields were calculated based on experimental results for the base case and modified cases. One modified case that integrated deacetylation, mechanical refining, and washing was estimated to produce 88 gallons of ethanol per ton of biomass. Conclusion The current work developed a novel bio-ethanol process that features pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. The new process shows improved overall ethanol yields compared to traditional dilute acid pretreatment. The experimental results from this work support the techno-economic analysis and calculation of Minimum Ethanol Selling Price (MESP) detailed in our companion paper. PMID:22888758

  14. Isolation, Characterization, and Ecology of Sulfur-Respiring Crenarchaea Inhabiting Acid-Sulfate-Chloride-Containing Geothermal Springs in Yellowstone National Park? †

    PubMed Central

    Boyd, Eric S.; Jackson, Robert A.; Encarnacion, Gem; Zahn, James A.; Beard, Trevor; Leavitt, William D.; Pi, Yundan; Zhang, Chuanlun L.; Pearson, Ann; Geesey, Gill G.

    2007-01-01

    Elemental sulfur (S0) is associated with many geochemically diverse hot springs, yet little is known about the phylogeny, physiology, and ecology of the organisms involved in its cycling. Here we report the isolation, characterization, and ecology of two novel, S0-reducing Crenarchaea from an acid geothermal spring referred to as Dragon Spring. Isolate 18U65 grows optimally at 70 to 72°C and at pH 2.5 to 3.0, while isolate 18D70 grows optimally at 81°C and pH 3.0. Both isolates are chemoorganotrophs, dependent on complex peptide-containing carbon sources, S0, and anaerobic conditions for respiration-dependent growth. Glycerol dialkyl glycerol tetraethers (GDGTs) containing four to six cyclopentyl rings were present in the lipid fraction of isolates 18U65 and 18D70. Physiological characterization suggests that the isolates are adapted to the physicochemical conditions of Dragon Spring and can utilize the natural organic matter in the spring as a carbon and energy source. Quantitative PCR analysis of 16S rRNA genes associated with the S0 flocs recovered from several acid geothermal springs using isolate-specific primers indicates that these two populations together represent 17 to 37% of the floc-associated DNA. The physiological characteristics of isolates 18U65 and 18D70 are consistent with their potential widespread distribution and putative role in the cycling of sulfur in acid geothermal springs throughout the Yellowstone National Park geothermal complex. Based on phenotypic and genetic characterization, the designations Caldisphaera draconis sp. nov. and Acidilobus sulfurireducens sp. nov. are proposed for isolates 18U65 and 18D70, respectively. PMID:17720836

  15. Using self-consistent Gibbs free energy surfaces to calculate size distributions of neutral and charged clusters for the sulfuric acid-water binary system

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Froyd, K. D.; Toon, O. B.

    2012-12-01

    We construct tables of reaction enthalpies and entropies for the association reactions involving sulfuric acid vapor, water vapor, and the bisulfate ion. These tables are created from experimental measurements and quantum chemical calculations for molecular clusters and a classical thermodynamic model for larger clusters. These initial tables are not thermodynamically consistent. For example, the Gibbs free energy of associating a cluster consisting of one acid molecule and two water molecules depends on the order in which the cluster was assembled: add two waters and then the acid or add an acid and a water and then the second water. We adjust the values within the tables using the method of Lagrange multipliers to minimize the adjustments and produce self-consistent Gibbs free energy surfaces for the neutral clusters and the charged clusters. With the self-consistent Gibbs free energy surfaces, we calculate size distributions of neutral and charged clusters for a variety of atmospheric conditions. Depending on the conditions, nucleation can be dominated by growth along the neutral channel or growth along the ion channel followed by ion-ion recombination.

  16. Differential responses of certain lichen species to sulfur-containing solutions under acidic conditions as expressed by the production of stress-ethylene.

    PubMed

    Garty, J; Kauppi, M; Kauppi, A

    1995-05-01

    To determine whether fluctuations in the concentration of ethylene produced by lichens exposed to sulfur-containing solutions at a low pH correlate with the tolerance/sensitivity of these lichens to air pollution, we measured the amount of ethylene produced by thalli soaked in H2SO4 and NaHSO3. The exposure of Hypogymnia physodes, Cladina stellaris, and Bryoria fuscescens to H2SO4 at a pH ranging between 4.0 and 2.0 did not produce changes in the concentration of ethylene in comparison with samples wetted with H2O at pH 6.8. The exposure of two pendulous lichens, Usnea hirta and Alectoria sarmentosa, to 1.0 and 5.0 mM H2SO4 at pH 2.7 and 2.0, respectively, stimulated only a slight increase of ethylene production, whereas another pendulous lichen, Bryoria fremontii, exposed to H2SO4 at pH 4.0-2.0 decreased its production of ethylene. The soaking of H. physodes, U. hirta, C. stellaris, and A. sarmentosa thalli in NaHSO3 at pH 4.0 gradually increased the production of ethylene. The exposure of B. fremontii and B. fuscescens to low NaHSO3 concentrations depressed the production of ethylene in these lichens. The indifference of H. physodes to H2SO4 under strong acidic conditions correlated with its resistance to SO2 in the air. In accordance with a model by D.M. Reid (In "Effects of Atmospheric Pollutants on Forests, Wetlands and Agricultural Ecosystems" (T.C. Hutchinson and K.M. Meema, Eds.), Vol G 16, pp. 241-245. NATO ASI Series, Springer-Verlag, Berlin and Heidelberg, 1987) referring to higher plants, it is suggested that sulfur-containing solutions under acidic conditions increase the solubility of particles containing heavy metals entrapped among the mycobiont hyphae in lichens. This may lead to an increase of the production of endogenous ethylene in lichens as they are exposed to sulfur-containing chemicals, to acidic rain, or to heavy metal-polluted air. PMID:8608772

  17. Differential responses of certain lichen species to sulfur-containing solutions under acidic conditions as expressed by the production of stress-ethylene

    SciTech Connect

    Garty, J. [Tel Aviv Univ. (Israel)] [Tel Aviv Univ. (Israel); Kauppi, M.; Kauppi, A. [Univ. of Oulu (Finland)] [Univ. of Oulu (Finland)

    1995-05-01

    To determine whether fluctuations in the concentration of ethylene produced by lichens exposed to sulfur-containing solutions at a low pH correlate with the tolerance/sensitivity of these lichens to air pollution, we measured the amount of ethylene produced by thalli soaked in H{sub 2}SO{sub 4} and NaHSO{sub 3}. The exposure of Hypogymnia physodes, Cladina stellaris, and Bryoria fuscescens to H{sub 2}SO{sub 4} at a pH ranging between 4.0 and 2.0 did not produce changes in the concentration of ethylene in comparison with samples wetted with H{sub 2}O at pH 6.8. The exposure of two pendulous lichens, Usnea hirta and Alectoria sarmentosa, to 1.0 and 5.0 mM H{sub 2}SO{sub 4} at pH 2.7 and 2.0, respectively, stimulated only a slight increase of ethylene production, whereas another pendulous lichen, Bryoria fremontii, exposed to H{sub 2}SO{sub 4} at pH 4.0-2.0 decreased its production of ethylene. The soaking of H. physodes, U. hirta, C. stellaris, and A. sarmentosa thalli in NaHSO{sub 3} at pH 4.0 gradually increased the production of ethylene. The exposure of B. fremontii and B. fuscescens to low NaHSO{sub 3} concentrations depressed the production of ethylene in these lichens. The indifference of H. physodes to H{sub 2}SO{sub 4} under strong acidic conditions correlated with its resistance to SO{sub 21} in the air. In accordance with a model by D.M. Reid (In {open_quotes}Effects of Atmospheric Pollutants on Forests, Wetlands and Agricultural Ecosystems. NATO ASI Series, Springer-Verlag, Berlin and Heidelberg, 1987) referring to higher plants, it is suggested that sulfur-containing solutions under acidic conditions increase the solubility of particles containing heavy metals entrapped among the mycobiont hyphae in lichens. This may lead to an increase of the production of endogenous ethylene in lichens as they are exposed to sulfur-containing chemicals, to acidic rain, or to heavy metal-polluted air. 65 refs., 8 tabs.

  18. Reactivity of pi-complexes of Ti, V, and Nb towards dithioacetic acid: Synthesis and structure of novel metal sulfur-containing complexes

    NASA Technical Reports Server (NTRS)

    Duraj, Stan A.; Andras, Maria T.; Hepp, Aloysius F.

    1990-01-01

    In order to use sulfur-containing resources economically and with minimal environmental damage, it is important to understand the desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent trends in materials chemistry, many model compounds warrant further study as catalyst precursors. The reactivity of low-valent organometallic sandwich pi-complexes toward dithiocarboxylic acids is described. For example, treatment of bisbenzene vanadium with CH3CSSH affords a divanadium tetrakis(dithioacetate) complex. The crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a V(mu-nu squared-S2)2V' unit in the mineral patonite (VS4)n. The stability of the V2S4 core in the dimer is demonstrated by evidence of V2S4(+) in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems relevant to HDS catalysis are also discussed.

  19. The Adsorption of Gold, Palladium, and Platinum from Acidic Chloride Solutions on Mesoporous Carbons

    SciTech Connect

    Peter R. Zalupski; Rocklan McDowell

    2014-10-01

    Studies on the adsorption characteristics of gold, palladium, and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II), and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of chloride ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces. The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5MHCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.

  20. The cmaR gene of Corynebacterium ammoniagenes performs a novel regulatory role in the metabolism of sulfur-containing amino acids.

    PubMed

    Lee, Seok-Myung; Hwang, Byung-Joon; Kim, Younhee; Lee, Heung-Shick

    2009-06-01

    A novel regulatory gene, which performs an essential function in sulfur metabolism, has been identified in Corynebacterium ammoniagenes and was designated cmaR (cysteine and methionine regulator in C. ammoniagenes). The cmaR-disrupted strain (DeltacmaR) lost the ability to grow on minimal medium, and was identified as a methionine and cysteine double auxotroph. The mutant strain proved unable to convert cysteine to methionine (and vice versa), and lost the ability to assimilate and reduce sulfate to sulfide. In the DeltacmaR strain, the mRNAs of the methionine biosynthetic genes metYX, metB and metFE were significantly reduced, and the activities of the methionine biosynthetic enzymes cystathionine gamma-synthase, O-acetylhomoserine sulfhydrylase, and cystathionine beta-lyase were relatively low, thereby suggesting that the cmaR gene exerts a positive regulatory effect on methionine biosynthetic genes. In addition, with the exception of cysK, reduced transcription levels of the sulfur-assimilatory genes cysIXYZ and cysHDN were noted in the cmaR-disrupted strain, which suggests that sulfur assimilation is also under the positive control of the cmaR gene. Furthermore, the expression of the cmaR gene itself was strongly induced via the addition of cysteine or methionine alone, but not the introduction of both amino acids together to the growth medium. In addition, the expression of the cmaR gene was enhanced in an mcbR-disrupted strain, which suggests that cmaR is under the negative control of McbR, which has been identified as a global regulator of sulfur metabolism. DNA binding of the purified CmaR protein to the promoter region of its target genes could be demonstrated in vitro. No metabolite effector was required for the protein to bind DNA. These results demonstrated that the cmaR gene of C. ammoniagenes plays a role similar to but distinct from that of the functional homologue cysR of Corynebacterium glutamicum. PMID:19383689