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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. Dilute sulfuric acid pretreatment of sunflower stalks for sugar production.

    PubMed

    Ruiz, Encarnación; Romero, Inmaculada; Moya, Manuel; Cara, Cristóbal; Vidal, Juan D; Castro, Eulogio

    2013-07-01

    In this work the pretreatment of sunflower stalks by dilute sulfuric acid is studied. Pretreatment temperature and the concentration of acid solution were selected as operation variables and modified according to a central rotatable composite experimental design. Based on previous studies pretreatment time was kept constant (5 min) while the variation range for temperature and acid concentration was centered at 175°C and 1.25% (w/v) respectively. Following pretreatment the insoluble solids were separated by filtration and further submitted to enzymatic hydrolysis, while liquid fractions were analyzed for sugars and inhibitors. Response surface methodology was applied to analyze results based on the combined severity of pretreatment experiments. Optimized results show that up to 33 g of glucose and xylose per 100g raw material (65% of the glucose and xylose present in the raw material) may be available for fermentation after pretreatment at 167°C and 1.3% sulfuric acid concentration.

  3. Dilute-sulfuric acid pretreatment of cattails for cellulose conversion.

    PubMed

    Zhang, Bo; Wang, Lijun; Shahbazi, Abolghasem; Diallo, Oumou; Whitmore, Allante

    2011-10-01

    The use of aquatic plant cattails to produce biofuel will add value to land and reduce emissions of greenhouse gases by replacing petroleum products. Dilute-sulfuric acid pretreatment of cattails was studied using a Dionex accelerated solvent extractor (ASE) varying acid concentration (0.1-1%), treatment temperature (140-180 °C), and residence time (5-10 min). The highest total glucose yield for both the pretreatment and enzyme hydrolysis stages (97.1% of the cellulose) was reached at a temperature of 180 °C, a sulfuric acid concentration of 0.5%, and a time of 5 min. Cattails pretreated with 0.5% sulfuric acid are digestible with similar results at enzyme loadings above 15 FPU/g glucan. Glucose from cattails cellulose can be efficiently fermented to ethanol with an approximately 90% of the theoretical yield. The results in this study indicate that cattails are a promising source of feedstock for advanced renewable fuel production.

  4. Dilute sulfuric acid pretreatment of transgenic switchgrass for sugar production.

    PubMed

    Zhou, Xu; Xu, Jiele; Wang, Ziyu; Cheng, Jay J; Li, Ruyu; Qu, Rongda

    2012-01-01

    Conventional Alamo switchgrass and its transgenic counterparts with reduced/modified lignin were subjected to dilute sulfuric acid pretreatment for improved sugar production. At 150 °C, the effects of acid concentration (0.75%, 1%, 1.25%) and residence time (5, 10, 20, 30 min) on sugar productions in pretreatment and enzymatic hydrolysis were investigated, with the optimal pretreatment conditions determined for each switchgrass genotype based on total sugar yield and the amounts of sugar degradation products generated during the pretreatment. The results show that genetic engineering, although did not cause an appreciable lignin reduction, resulted in a substantial increase in the ratio of acid soluble lignin:acid insoluble lignin, which led to considerably increased sugar productions in both pretreatment and enzymatic hydrolysis. At an elevated threshold concentration of combined 5-hydroxyfuranmethal and furfural (2.0 g/L), the overall carbohydrate conversions of conventional switchgrass and its transgenic counterparts, 10/9-40 and 11/5-47, reached 75.9%, 82.6%, and 82.2%, respectively.

  5. Recovery and separation of sulfuric acid and iron from dilute acidic sulfate effluent and waste sulfuric acid by solvent extraction and stripping.

    PubMed

    Qifeng, Wei; Xiulian, Ren; Jingjing, Guo; Yongxing, Chen

    2016-03-05

    The recovery and simultaneous separation of sulfuric acid and iron from dilute acidic sulfate effluent (DASE) and waste sulfuric acid (WSA) have been an earnest wish for researchers and the entire sulfate process-based titanium pigment industry. To reduce the pollution of the waste acid and make a comprehensive use of the iron and sulfuric acid in it, a new environmentally friendly recovery and separation process for the DASE and the WSA is proposed. This process is based on the reactive extraction of sulfuric acid and Fe(III) from the DASE. Simultaneously, stripping of Fe(III) is carried out in the loaded organic phase with the WSA. Compared to the conventional ways, this innovative method allows the effective extraction of sulfuric acid and iron from the DASE, and the stripping of Fe(III) from the loaded organic phase with the WSA. Trioctylamine (TOA) and tributyl phosphate (TBP) in kerosene (10-50%) were used as organic phases for solvent extraction. Under the optimal conditions, about 98% of Fe(III) and sulfuric acid were removed from the DASE, and about 99.9% of Fe(III) in the organic phase was stripped with the WSA.

  6. Rapid analysis of barley straw before and after dilute sulfuric acid pretreatment by photoluminescence.

    PubMed

    Kim, Sung Bong; Cui, Chunzhi; Lee, Ja Hyun; Lee, Sang Jun; Ahn, Dong June; Park, Chulhwan; Kim, Jun Seok; Kim, Seung Wook

    2013-10-01

    The fluorescence intensities (FIs) of raw and pretreated barley straws were measured by fluorescence microscopy, and the difference in the fluorescence intensity of barley straw before and after dilute acid pretreatment was analyzed by investigation of the major compounds of barley straw. The difference in fluorescence intensity was due to the difference in xylan content. Barley straw was pretreated using dilute sulfuric acid at various conditions and the correlation between the fluorescence intensity and glucose yield of barley straw was investigated. The coefficient of determination (R(2)) of the correlation was found to be 72.28%. Also the calibration of fluorescence intensity with the xylan content was performed. In addition, the absorption and emission spectra of the raw and the pretreated barley straw were examined to verify the proposed method. The absorption and emission wave lengths were 550 nm and 665 nm, respectively.

  7. Titanium leaching from red mud by diluted sulfuric acid at atmospheric pressure.

    PubMed

    Agatzini-Leonardou, S; Oustadakis, P; Tsakiridis, P E; Markopoulos, Ch

    2008-09-15

    Laboratory-scale research has focused on the recovery of titanium from red mud, which is obtained from bauxite during the Bayer process for alumina production. The leaching process is based on the extraction of this element with diluted sulfuric acid from red mud 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 titanium recovery efficiency on the basis of red mud weight reached 64.5%. The characterization of the initial red mud, as well as this of the leached residues was carried out by X-ray diffraction, TG-DTA and scanning electron microscopy.

  8. Scale-up of diluted sulfuric acid hydrolysis for producing sugarcane bagasse hemicellulosic hydrolysate (SBHH).

    PubMed

    Rodrigues, Rita de Cássia L B; Rocha, George J M; Rodrigues, Durval; Filho, Hélcio J I; Felipe, Maria das Graças A; Pessoa, Adalberto

    2010-02-01

    Sugarcane bagasse was pretreated with diluted sulfuric acid to obtain sugarcane bagasse hemicellulosic hydrolysate (SBHH). Experiments were conducted in laboratory and semi-pilot reactors to optimize the xylose recovery and to reduce the generation of sugar degradation products, as furfural and 5-hydroxymethylfurfural (HMF). The hydrolysis scale-up procedure was based on the H-Factor, that combines temperature and residence time and employs the Arrhenius equation to model the sulfuric acid concentration (100 mg(acid)/g(dm)) and activation energy (109 kJ/mol). This procedure allowed the mathematical estimation of the results through simulation of the conditions prevailing in the reactors with different designs. The SBHH obtained from different reactors but under the same H-Factor of 5.45+/-0.15 reached similar xylose yield (approximately 74%) and low concentration of sugar degradation products, as furfural (0.082 g/L) and HMF (0.0071 g/L). Also, the highest lignin degradation products (phenolic compounds) were rho-coumarilic acid (0.15 g/L) followed by ferulic acid (0.12 g/L) and gallic acid (0.035 g/L). The highest concentration of ions referred to S (3433.6 mg/L), Fe (554.4 mg/L), K (103.9 mg/L). The H-Factor could be used without dramatically altering the xylose and HMF/furfural levels. Therefore, we could assume that H-Factor was directly useful in the scale-up of the hemicellulosic hydrolysate production.

  9. 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.

  10. Nickel recovery from spent Raneynickel catalyst through dilute sulfuric acid leaching and soda ash precipitation.

    PubMed

    Lee, Jin Young; Rao, S Venkateswara; Kumar, B Nagaphani; Kang, Dong Jun; Reddy, B Ramachandra

    2010-04-15

    Pharmaceutical industry makes extensive use of Raneynickel catalyst for various organic drug intermediates/end products. Spent catalysts contain environmentally critical and economically valuable metals. In the present study, a simple hydrometallurgical process using dilute sulfuric acid leaching was described for the recovery of nickel from spent Raneynickel catalyst. Recovery of nickel varied with acid concentration and time, whereas temperature had negligible effect. Increase of S/L ratio to 30% (w/v) showed marginal effect on nickel (90%) recovery, whereas Al recovery decreased drastically to approximately 20%. Under the optimum conditions of leaching viz: 12 vol.% H(2)SO(4), 30 degrees C, 20% solid to liquid (S/L) ratio and 120 min reaction time, it was possible to recover 98.6% Ni along with 39.2% Al. Leach liquor [pH 0.7] containing 85.0 g/L Ni and 3.25 g/L Al was adjusted to pH 5.4 with 30 wt.% alkali for quantitative aluminum removal. Nickel loss was about 2% during this Al removal step. Nickel from the purified leach liquor was recovered as nickel carbonate by adding required amount of Na(2)CO(3). The purity of NiCO(3) product was found to be 100% with a Ni content of 48.6%. Na(2)SO(4) was recovered as a by-product with a purity of 99%. Complete process is presented.

  11. Reversion and dehydration reactions of glucose during the dilute sulfuric acid hydrolysis of cellulose

    SciTech Connect

    Helm, R.F.

    1987-01-01

    The inaccessibility of all glycosidic bonds necessitates industrial conversion schemes which employ a dilute acid catalyst at high temperatures. Process conditions also promote further reactions of glucose via the reversion and dehydration pathways. Quantitative determination of the yields of the major reversion and dehydration products is important for understanding and predicting the amounts of these materials expected under envisioned industrial operating conditions. Microcrystalline cellulose (Avicel) was hydrolyzed with sulfuric acid (0.0-1.25 wt.%), at high temperatures (160-250/sup 0/C), and at a 3:1 liquid-to-solid ratio. The hydrolysis was monitored by evaluating the amount of cellulose remaining and the yields of glucose, solid humin, levulinic acid, formic acid, hydroxymethylfurfural (HMF), and reversion products as a function of the aforementioned reaction conditions. Analysis of the reversion products required the development of a technique for the quantitation of trace carbohydrates in complex mixtures and led to the development of a reduction/permethylation gas chromatographic procedure. Cellulose hydrolysis followed pseudo-homogeneous first-order kinetics. Glucose yield was adequately described as consecutive first-order reactions. Anhydrosugars formed via reversion followed equilibrium reaction kinetics whereas the disaccharides did not. Total reversion product yields approached 10% at 250/sup 0/C. Quantitative determination of the major dehydration products provided important information concerning the destruction of glucose. HMF was produced in up to 12% yields based on the theoretical amount of glucose available, and furfural was detected in up to 5% yields. A carbon mass balance based on the determined product yields revealed that approximately 90% of all carbon was accounted for at maximum glucose yields.

  12. Optimization of thermal-dilute sulfuric acid pretreatment for enhancement of methane production from cassava residues.

    PubMed

    Zhang, Qinghua; Tang, Lei; Zhang, Jianhua; Mao, Zhonggui; Jiang, Li

    2011-02-01

    In this study, the pretreatment of cassava residues by thermal-dilute sulfuric acid (TDSA) hydrolysis was investigated by means of a statistically designed set of experiments. A three-factor central composite design (CCD) was employed to identify the optimum pretreatment condition of cassava residues for methane production. The individual and interactive effects of temperature, H(2)SO(4) concentration and reaction time on increase of methane yield (IMY) were evaluated by applying response surface methodology (RSM). After optimization, the resulting optimum pretreatment condition was 157.84°C, utilizing 2.99% (w/w TS) H(2)SO(4) for 20.15 min, where the maximum methane yield (248 mL/g VS) was 56.96% higher than the control (158 mL/g VS), which was very close to the predict value 56.53%. These results indicate the model obtained through RSM analysis is suit to predict the optimum pretreatment condition and there is great potential of using TDSA pretreatment of cassava residues to enhance methane yield.

  13. Production of spent mushroom substrate hydrolysates useful for cultivation of Lactococcus lactis by dilute sulfuric acid, cellulase and xylanase treatment.

    PubMed

    Qiao, Jian-Jun; Zhang, Yan-Fei; Sun, Li-Fan; Liu, Wei-Wei; Zhu, Hong-Ji; Zhang, Zhijun

    2011-09-01

    Spent mushroom substrate (SMS) was treated with dilute sulfuric acid followed by cellulase and xylanase treatment to produce hydrolysates that could be used as the basis for media for the production of value added products. A L9 (3(4)) orthogonal experiment was performed to optimize the acid treatment process. Pretreatment with 6% (w/w) dilute sulfuric acid at 120°C for 120 min provided the highest reducing sugar yield of 267.57 g/kg SMS. No furfural was detected in the hydrolysates. Exposure to 20PFU of cellulase and 200 XU of xylanase per gram of pretreated SMS at 40°C resulted in the release of 79.85 g/kg or reducing sugars per kg acid pretreated SMS. The dilute sulfuric acid could be recycled to process fresh SMS four times. SMS hydrolysates neutralized with ammonium hydroxide, sodium hydroxide, or calcium hydroxide could be used as the carbon source for cultivation of Lactococcus lactis subsp. lactis W28 and a cell density of 2.9×10(11)CFU/mL could be obtained. The results provide a foundation for the development of value-added products based on SMS.

  14. Pretreatment of Sugar Beet Pulp with Dilute Sulfurous Acid is Effective for Multipurpose Usage of Carbohydrates.

    PubMed

    Kharina, M; Emelyanov, V; Mokshina, N; Ibragimova, N; Gorshkova, T

    2016-05-01

    Sulfurous acid was used for pretreatment of sugar beet pulp (SBP) in order to achieve high efficiency of both extraction of carbohydrates and subsequent enzymatic hydrolysis of the remaining solids. The main advantage of sulfurous acid usage as pretreatment agent is the possibility of its regeneration. Application of sulfurous acid as hydrolyzing agent in relatively low concentrations (0.6-1.0 %) during a short period of time (10-20 min) and low solid to liquid ratio (1:3, 1:6) allowed effective extraction of carbohydrates from SBP and provided positive effect on subsequent enzymatic hydrolysis. The highest obtained concentration of reducing substances (RS) in hydrolysates was 8.5 %; up to 33.6 % of all carbohydrates present in SBP could be extracted. The major obtained monosaccharides were arabinose and glucose (9.4 and 7.3 g/l, respectively). Pretreatment of SBP with sulfurous acid increased 4.6 times the yield of glucose during subsequent enzymatic hydrolysis of remaining solids with cellulase cocktail, as compared to the untreated SBP. Total yield of glucose during SBP pretreatment and subsequent enzymatic hydrolysis amounted to 89.4 % of the theoretical yield. The approach can be applied directly to the wet SBP. Hydrolysis of sugar beet pulp with sulfurous acid is recommended for obtaining of individual monosaccharides, as well as nutritional media.

  15. 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 ...

  16. Comparative techno-economic analysis of steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological pretreatments of corn stover.

    PubMed

    Baral, Nawa Raj; Shah, Ajay

    2017-05-01

    Pretreatment is required to destroy recalcitrant structure of lignocelluloses and then transform into fermentable sugars. This study assessed techno-economics of steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological pretreatments, and identified bottlenecks and operational targets for process improvement. Techno-economic models of these pretreatment processes for a cellulosic biorefinery of 113.5 million liters butanol per year excluding fermentation and wastewater treatment sections were developed using a modelling software-SuperPro Designer. Experimental data of the selected pretreatment processes based on corn stover were gathered from recent publications, and used for this analysis. Estimated sugar production costs ($/kg) via steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological methods were 0.43, 0.42, 0.65 and 1.41, respectively. The results suggest steam explosion and sulfuric acid pretreatment methods might be good alternatives at present state of technology and other pretreatment methods require research and development efforts to be competitive with these pretreatment methods.

  17. Temperature shifts for extraction and purification of zygomycetes chitosan with dilute sulfuric acid.

    PubMed

    Zamani, Akram; Edebo, Lars; Niklasson, Claes; Taherzadeh, Mohammad J

    2010-08-13

    The temperature-dependent hydrolysis and solubility of chitosan in sulfuric acid solutions offer the possibility for chitosan extraction from zygomycetes mycelia and separation from other cellular ingredients with high purity and high recovery. In this study, Rhizomucor pusillus biomass was initially extracted with 0.5 M NaOH at 120 °C for 20 min, leaving an alkali insoluble material (AIM) rich in chitosan. Then, the AIM was subjected to two steps treatment with 72 mM sulfuric acid at (i) room temperature for 10 min followed by (ii) 120 °C for 45 min. During the first step, phosphate of the AIM was released into the acid solution and separated from the chitosan-rich residue by centrifugation. In the second step, the residual AIM was re-suspended in fresh 72 mM sulfuric acid, heated at 120 °C and hot filtered, whereby chitosan was extracted and separated from the hot alkali and acid insoluble material (HAAIM). The chitosan was recovered from the acid solution by precipitation at lowered temperature and raised pH to 8-10. The treatment resulted in 0.34 g chitosan and 0.16 g HAAIM from each gram AIM. At the start, the AIM contained at least 17% phosphate, whereas after the purification, the corresponding phosphate content of the obtained chitosan was just 1%. The purity of this chitosan was higher than 83%. The AIM subjected directly to the treatment with hot sulfuric acid (at 120 °C for 45 min) resulted in a chitosan with a phosphate impurity of 18.5%.

  18. Impact of recycling stillage on conversion of dilute sulfuric acid pretreated corn stover to ethanol.

    PubMed

    Mohagheghi, Ali; Schell, Daniel J

    2010-04-01

    Both the current corn starch to ethanol industry and the emerging lignocellulosic biofuels industry view recycling of spent fermentation broth or stillage as a method to reduce fresh water use. The objective of this study was to understand the impact of recycling stillage on conversion of corn stover to ethanol. Sugars in a dilute-acid pretreated corn stover hydrolysate were fermented to ethanol by the glucose-xylose fermenting bacteria Zymomonas mobilis 8b. Three serial fermentations were performed at two different initial sugar concentrations using either 10% or 25% of the stillage as makeup water for the next fermentation in the series. Serial fermentations were performed to achieve near steady state concentration of inhibitors and other compounds in the corn stover hydrolysate. Little impact on ethanol yields was seen at sugar concentrations equivalent to pretreated corn stover slurry at 15% (w/w) with 10% recycle of the stillage. However, ethanol yields became progressively poorer as the sugar concentration increased and fraction of the stillage recycled increased. At an equivalent corn stover slurry concentration of 20% with 25% recycled stillage the ethanol yield was only 5%. For this microorganism with dilute-acid pretreated corn stover, recycling a large fraction of the stillage had a significant negative impact on fermentation performance. Although this finding is of concern for biochemical-based lignocellulose conversion processes, other microorganism/pretreatment technology combinations will likely perform differently.

  19. Dilute sulfuric acid pretreatment of agricultural and agro-industrial residues for ethanol production.

    PubMed

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

    2007-04-01

    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 degrees C during 20, 40, or 60 min using 2% H(2)SO(4) 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.

  20. 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.

  1. Levulinic acid production by two-step acid-catalyzed treatment of Quercus mongolica using dilute sulfuric acid.

    PubMed

    Jeong, Hanseob; Jang, Soo-Kyeong; Hong, Chang-Young; Kim, Seon-Hong; Lee, Su-Yeon; Lee, Soo Min; Choi, Joon Weon; Choi, In-Gyu

    2017-02-01

    The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter (reaction temperature range: 100-230°C; sulfuric acid (SA) concentration range: 0-2%) on the levulinic acid yield. After 1(st) step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6gg/100gbiomass) were released into the liquid hydrolysate at the reaction temperature of 150°C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2(nd) step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5g/100g biomass of levulinic acid was produced at the reaction temperature of 200°C in 2% SA, corresponding to a higher conversion rate than during single-step treatment.

  2. Production of furfural from xylose at atmospheric pressure by dilute sulfuric acid and inorganic salts.

    PubMed

    Rong, Chunguang; Ding, Xuefeng; Zhu, Yanchao; Li, Ying; Wang, Lili; Qu, Yuning; Ma, Xiaoyu; Wang, Zichen

    2012-03-01

    In this paper, the dehydration of xylose to furfural was carried out under atmospheric pressure and at the boiling temperature of a biphasic mixture of toluene and an aqueous solution of xylose, with sulfuric acid as catalyst plus an inorganic salt (NaCl or FeCl(3)) as promoter. The best yield of furfural was 83% under the following conditions: 150 mL of toluene and 10 mL of aqueous solution of 10% xylose (w/w), 10% H(2)SO(4) (w/w), 2.4g NaCl , and heating for 5h. FeCl(3) as promoter was found to be more efficient than NaCl. The addition of DMSO to the aqueous phase in the absence of an inorganic salt was shown to improve the yield of furfural.

  3. Sulfuric acid-sulfur heat storage cycle

    DOEpatents

    Norman, John H.

    1983-12-20

    A method of storing heat is provided utilizing a chemical cycle which interconverts sulfuric acid and sulfur. The method can be used to levelize the energy obtained from intermittent heat sources, such as solar collectors. Dilute sulfuric acid is concentrated by evaporation of water, and the concentrated sulfuric acid is boiled and decomposed using intense heat from the heat source, forming sulfur dioxide and oxygen. The sulfur dioxide is reacted with water in a disproportionation reaction yielding dilute sulfuric acid, which is recycled, and elemental sulfur. The sulfur has substantial potential chemical energy and represents the storage of a significant portion of the energy obtained from the heat source. The sulfur is burned whenever required to release the stored energy. A particularly advantageous use of the heat storage method is in conjunction with a solar-powered facility which uses the Bunsen reaction in a water-splitting process. The energy storage method is used to levelize the availability of solar energy while some of the sulfur dioxide produced in the heat storage reactions is converted to sulfuric acid in the Bunsen reaction.

  4. Impact of pretreatment with dilute sulfuric acid under moderate temperature on hydrolysis of corn stover with two enzyme systems.

    PubMed

    Tai, Chao; Keshwani, Deepak

    2014-03-01

    Pretreatment of corn stover with dilute sulfuric acid at moderate temperature was investigated, and glucan digestibility by Cellic CTec2 and Celluclast on the pretreated biomass was compared. Pretreatments were carried out from 60 to 180 min at the temperature from 105 to 135 °C, with acid concentrations ranging from 0.5 to 2% (w/v). Significant portion of xylan was removed during pretreatment, and the glucan digestibility by CTec2 was significantly better than that by Celluclast in all cases. Analysis showed that glucan digestibility by both two enzymes correlated directly with the extent of xylan removal in pretreatment. Confidence interval was built to give a more precise range of glucan conversion and to test the significant difference among pretreatment conditions. Response surface model was built to obtain the optimal pretreatment condition to achieve high glucan conversion after enzymatic hydrolysis. Considering the cost and energy savings, the optimal pretreatment condition of 1.75% acid for 160 min at 135 °C was determined, and glucan conversion can achieve the range from 72.86 to 76.69% at 95% confidence level after enzymatic hydrolysis, making total glucan recovery up to the range from 89.42 to 93.25%.

  5. Oil production by oleaginous yeasts using the hydrolysate from pretreatment of wheat straw with dilute sulfuric acid.

    PubMed

    Yu, Xiaochen; Zheng, Yubin; Dorgan, Kathleen M; Chen, Shulin

    2011-05-01

    This paper explores the use of the hydrolysate from the dilute sulfuric acid pretreatment of wheat straw for microbial oil production. The resulting hydrolysate was composed of pentoses (24.3g/L) and hexoses (4.9 g/L), along with some other degradation products, such as acetic acid, furfural, and hydroxymethylfurfural (HMF). Five oleaginous yeast strains, Cryptococcus curvatus, Rhodotorula glutinis, Rhodosporidium toruloides, Lipomyces starkeyi, and Yarrowia lipolytica, were evaluated by using this hydrolysate as substrates. The results showed that all of these strains could use the detoxified hydrolysate to produce lipids while except R. toruloides non-detoxified hydrolysate could also be used for the growth of all of the selective yeast strains. C. curvatus showed the highest lipid concentrations in medium on both the detoxified (4.2g/L) and non-detoxified (5.8 g/L) hydrolysates. And the inhibitory effect studies on C. curvatus indicated HMF had insignificant impacts at a concentration of up to 3g/L while furfural inhibited cell growth and lipid content by 72.0% and 62.0% at 1g/L, respectively. Our work demonstrates that lipid production is a promising alternative to utilize hemicellulosic sugars obtained during pretreatment of lignocellulosic materials.

  6. High yield production of sugars from deproteinated palm kernel cake under microwave irradiation via dilute sulfuric acid hydrolysis.

    PubMed

    Fan, Suet-Pin; Jiang, Li-Qun; Chia, Chin-Hua; Fang, Zhen; Zakaria, Sarani; Chee, Kah-Leong

    2014-02-01

    Recent years, great interest has been devoted to the conversion of biomass-derived carbohydrate into sugars, such as glucose, mannose and fructose. These are important versatile intermediate products that are easily processed into high value-added biofuels. In this work, microwave-assisted dilute sulfuric acid hydrolysis of deproteinated palm kernel cake (DPKC) was systematically studied using Response Surface Methodology. The highest mannose yield (92.11%) was achieved at the optimized condition of 148°C, 0.75N H2SO4, 10min 31s and substrate to solvent (SS) ratio (w/v) of 1:49.69. Besides that, total fermentable sugars yield (77.11%), was obtained at 170°C, 0.181N H2SO4, 6min 6s and SS ratio (w/v) of 1:40. Ridge analysis was employed to further verify the optimum conditions. Thus, this work provides fundamental data of the practical use of DPKC as low cost, high yield and environmental-friendly material for the production of mannose and other sugars.

  7. A comparison of dilute aqueous p-toluenesulfonic and sulfuric acid pretreatments and saccharification of corn stover at moderate temperatures and pressures.

    PubMed

    Amarasekara, Ananda S; Wiredu, Bernard

    2012-12-01

    Single step pretreatment-saccharification of corn stover was investigated in aqueous p-toluenesulfonic and sulfuric acid media. Dilute aqueous solution of p-toluenesulfonic acid was a better catalyst than aqueous sulfuric acid of the same H(+) ion concentration for single step pretreatment-saccharification of corn stover at moderate temperatures and pressures. For example, 100mg corn stover heated at 150°C for 1h in 0.100 M H(+) aqueous sulfuric acid produced 64 μmol of total reducing sugars (TRS), whereas the sample heated in 0.100 M H(+)p-toluenesulfonic acid produced 165 μmol of TRS under identical conditions. Glucose yield showed a similar trend, as aq. sulfuric acid and p-toluene sulfonic acid media produced 29 and 35 μmol of glucose respectively after 2.5h. Higher catalytic activity of p-toluenesulfonic acid may be due to an interaction with biomass, supported by repulsion of hydrophobic tolyl group by the aqueous phase.

  8. Sulfuric acid poisoning

    MedlinePlus

    Sulfuric acid is a very strong chemical that is corrosive. Corrosive means it can cause severe burns and ... or mucous membranes. This article discusses poisoning from sulfuric acid. This article is for information only. Do NOT ...

  9. 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.

  10. Optimization of dilute sulfuric acid pretreatment to maximize combined sugar yield from sugarcane bagasse for ethanol production.

    PubMed

    Benjamin, Y; Cheng, H; Görgens, J F

    2014-01-01

    Increasing fermentable sugar yields per gram of biomass depends strongly on optimal selection of varieties and optimization of pretreatment conditions. In this study, dilute acid pretreatment of bagasse from six varieties of sugarcane was investigated in connection with enzymatic hydrolysis for maximum combined sugar yield (CSY). The CSY from the varieties were also compared with the results from industrial bagasse. The results revealed considerable differences in CSY between the varieties. Up to 22.7 % differences in CSY at the optimal conditions was observed. The combined sugar yield difference between the best performing variety and the industrial bagasse was 34.1 %. High ratio of carbohydrates to lignin and low ash content favored the release of sugar from the substrates. At mild pretreatment conditions, the differences in bioconversion efficiency between varieties were greater than at severe condition. This observation suggests that under less severe conditions the glucose recovery was largely determined by chemical composition of biomass. The results from this study support the possibility of increasing sugar yields or improving the conversion efficiency when pretreatment optimization is performed on varieties with improved properties.

  11. Enzymatic hydrolysis and fermentation of pretreated cashew apple bagasse with alkali and diluted sulfuric Acid for bioethanol production.

    PubMed

    Rocha, Maria Valderez Ponte; Rodrigues, Tigressa Helena Soares; de Macedo, Gorete Ribeiro; Gonçalves, Luciana R B

    2009-05-01

    The aim of this work was to optimize the enzymatic hydrolysis of the cellulose fraction of cashew apple bagasse (CAB) after diluted acid (CAB-H) and alkali pretreatment (CAB-OH), and to evaluate its fermentation to ethanol using Saccharomyces cerevisiae. Glucose conversion of 82 +/- 2 mg/g CAB-H and 730 +/- 20 mg/g CAB-OH was obtained when 2% (w/v) of solid and 30 FPU/g bagasse was used during hydrolysis at 45 degrees C, 2-fold higher than when using 15 FPU/g bagasse, 44 +/- 2 mg/g CAB-H, and 450 +/- 50 mg/g CAB-OH, respectively. Ethanol concentration and productivity, achieved after 6 h of fermentation, were 20.0 +/- 0.2 g L(-1) and 3.33 g L(-1) h(-1), respectively, when using CAB-OH hydrolyzate (initial glucose concentration of 52.4 g L(-1)). For CAB-H hydrolyzate (initial glucose concentration of 17.4 g L(-1)), ethanol concentration and productivity were 8.2 +/- 0.1 g L(-1) and 2.7 g L(-1) h(-1) in 3 h, respectively. Hydrolyzates fermentation resulted in an ethanol yield of 0.38 and 0.47 g/g glucose with pretreated CAB-OH and CAB-H, respectively. Ethanol concentration and productivity, obtained using CAB-OH hydrolyzate, were close to the values obtained in the conventional ethanol fermentation of cashew apple juice or sugar cane juice.

  12. Dilute-sulfuric acid pretreatment of corn stover in pilot-scale reactor: investigation of yields, kinetics, and enzymatic digestibilities of solids.

    PubMed

    Schell, Daniel J; Farmer, Jody; Newman, Millie; McMillan, James D

    2003-01-01

    Corn stover is a domestic feedstock that has potential to produce significant quantities of fuel ethanol and other bioenergy and biobased products. However, comprehensive yield and carbon mass balance information and validated kinetic models for dilute-sulfuric acid (H2SO4) pretreatment of corn stover have not been available. This has hindered the estimation of process economics and also limited the ability to perform technoeconomic modeling to guide research. To better characterize pretreatment and assess its kinetics, we pretreated corn stover in a continuous 1 t/d reactor. Corn stover was pretreated at 20% (w/w) solids concentration over a range of conditions encompassing residence times of 3-12 min, temperatures of 165- 195 degrees C, and H2SO4 concentrations of 0.5-1.4% (w/w). Xylan conversion yield and carbon mass balance data were collected at each run condition. Performance results were used to estimate kinetic model parameters assuming biphasic hemicellulose hydrolysis and a hydrolysis mechanism incorporating formation of intermediate xylo-oligomers. In addition, some of the pretreated solids were tested in a simultaneous saccharification and fermentation (SSF) process to measure the reactivity of their cellulose component to enzymatic digestion by cellulase enzymes. Monomeric xylose yields of 69-71% and total xylose yields (monomers and oligomers) of 70-77% were achieved with performance level depending on pretreatment severity. Cellulose conversion yields in SSF of 80-87% were obtained for some of the most digestible pretreated solids.

  13. Characterization of commercial cellulases and their use in the saccharification of a sugarcane bagasse sample pretreated with dilute sulfuric acid.

    PubMed

    Santos, Victor T O; Esteves, Paula J; Milagres, Adriane M F; Carvalho, Walter

    2011-08-01

    This study aimed to correlate the efficiency of enzymatic hydrolysis of the cellulose contained in a sugarcane bagasse sample pretreated with dilute H(2)SO(4) with the levels of independent variables such as initial content of solids and loadings of enzymes and surfactant (Tween 20), for two cellulolytic commercial preparations. The preparations, designated cellulase I and cellulase II, were characterized regarding the activities of total cellulases, endoglucanase, cellobiohydrolase, cellobiase, β-glucosidase, xylanase, and phenoloxidases (laccase, manganese and lignin peroxidases), as well as protein contents. Both extracts showed complete cellulolytic complexes and considerable activities of xylanases, without activities of phenoloxidases. For the enzymatic hydrolyses, two 2(3) central composite full factorial designs were employed to evaluate the effects caused by the initial content of solids (1.19-4.81%, w/w) and loadings of enzymes (1.9-38.1 FPU/g bagasse) and Tween 20 (0.0-0.1 g/g bagasse) on the cellulose digestibility. Within 24 h of enzymatic hydrolysis, all three independent variables influenced the conversion of cellulose by cellulase I. Using cellulase II, only enzyme and surfactant loadings showed significant effects on cellulose conversion. An additional experiment demonstrated the possibility of increasing the initial content of solids to values much higher than 4.81% (w/w) without compromising the efficiency of cellulose conversion, consequently improving the glucose concentration in the hydrolysate.

  14. 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.

  15. Solubility of Sulfur Dioxide in Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Chang, K. K.; Compton, L. E.; Lawson, D. D.

    1982-01-01

    The solubility of sulfur dioxide in 50% (wt./wt.) sulfuric acid was evaluated by regular solution theory, and the results verified by experimental measurements in the temperature range of 25 C to 70 C at pressures of 60 to 200 PSIA. The percent (wt./wt.) of sulfur dioxide in 50% (wt./wt.) sulfuric acid is given by the equation %SO2 = 2.2350 + 0.0903P - 0.00026P 10 to the 2nd power with P in PSIA.

  16. Sulfuric acid on Europa and the radiolytic sulfur cycle

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Johnson, R. E.; Anderson, M. S.

    1999-01-01

    A comparison of laboratory spectra with Galileo data indicates that hydrated sulfuric acid is present and is a major component of Europa's surface. In addition, this moon's visually dark surface material, which spatially correlates with the sulfuric acid concentration, is identified as radiolytically altered sulfur polymers. Radiolysis of the surface by magnetospheric plasma bombardment continuously cycles sulfur between three forms: sulfuric acid, sulfur dioxide, and sulfur polymers, with sulfuric acid being about 50 times as abundant as the other forms. Enhanced sulfuric acid concentrations are found in Europa's geologically young terrains, suggesting that low-temperature, liquid sulfuric acid may influence geological processes.

  17. Sulfuric acid on Europa and the radiolytic sulfur cycle.

    PubMed

    Carlson, R W; Johnson, R E; Anderson, M S

    1999-10-01

    A comparison of laboratory spectra with Galileo data indicates that hydrated sulfuric acid is present and is a major component of Europa's surface. In addition, this moon's visually dark surface material, which spatially correlates with the sulfuric acid concentration, is identified as radiolytically altered sulfur polymers. Radiolysis of the surface by magnetospheric plasma bombardment continuously cycles sulfur between three forms: sulfuric acid, sulfur dioxide, and sulfur polymers, with sulfuric acid being about 50 times as abundant as the other forms. Enhanced sulfuric acid concentrations are found in Europa's geologically young terrains, suggesting that low-temperature, liquid sulfuric acid may influence geological processes.

  18. Process for forming sulfuric acid

    DOEpatents

    Lu, Wen-Tong P.

    1981-01-01

    An improved electrode is disclosed for the anode in a sulfur cycle hydrogen generation process where sulfur dioxie is oxidized to form sulfuric acid at the anode. The active compound in the electrode is palladium, palladium oxide, an alloy of palladium, or a mixture thereof. The active compound may be deposited on a porous, stable, conductive substrate.

  19. 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…

  20. Sulfuric acid as autocatalyst in the formation of sulfuric acid.

    PubMed

    Torrent-Sucarrat, Miquel; Francisco, Joseph S; Anglada, Josep M

    2012-12-26

    Sulfuric acid can act as a catalyst of its own formation. We have carried out a computational investigation on the gas-phase formation of H(2)SO(4) by hydrolysis of SO(3) involving one and two water molecules, and also in the presence of sulfuric acid and its complexes with one and two water molecules. The hydrolysis of SO(3) requires the concurrence of two water molecules, one of them acting as a catalyzer, and our results predict an important catalytic effect, ranging between 3 and 11 kcal·mol(-1) when the catalytic water molecule is substituted by a sulfuric acid molecule or one of its hydrates. In these cases, the reaction products are either bare sulfuric acid dimer or sulfuric acid dimer complexed with a water molecule. There are broad implications from these new findings. The results of the present investigation show that the catalytic effect of sulfuric acid in the SO(3) hydrolysis can be important in the Earth's stratosphere, in the heterogeneous formation of sulfuric acid and in the formation of aerosols, in H(2)SO(4) formation by aircraft engines, and also in understanding the formation of sulfuric acid in the atmosphere of Venus.

  1. Bioconversion of sawdust into ethanol using dilute sulfuric acid-assisted continuous twin screw-driven reactor pretreatment and fed-batch simultaneous saccharification and fermentation.

    PubMed

    Kim, Tae Hyun; Choi, Chang Ho; Oh, Kyeong Keun

    2013-02-01

    Ethanol production from poplar sawdust using sulfuric acid-assisted continuous twin screw-driven reactor (CTSR) pretreatment followed by simultaneous saccharification and fermentation (SSF) was investigated. Pretreatment with high acid concentration increased the cellulose content in the pretreated solid (74.9-76.9% in the range of 4.0-5.5wt.% H(2)SO(4)). The sugar content (XMG; xylan+mannan+galactan) in the treated-solid was 11.1-15.2% and 0.9-5.7% with 0.5wt.% and 7.0wt.%, respectively. The XMG recovery yield of the sample treated with 4.0wt.% H(2)SO(4) at 185°C was maximized at 88.6%. Enzymatic hydrolysis test showed a cellulose digestibility of 67.1%, 70.1%, and 73.6% with 15, 30, and 45FPU/g-cellulose, respectively. In the fed-batch SSF tests with initial enzyme addition, the ethanol yield of each stage almost reached a maximum at 28h, 48h, and 56h, respectively, with yields of 63.9% (16.5g/L), 78.4% (30.1g/L), and 81.7% (39.9g/L), respectively.

  2. Sugar yields from dilute oxalic acid pretreatment of maple wood compared to those with other dilute acids and hot water.

    PubMed

    Zhang, Taiying; Kumar, Rajeev; Wyman, Charles E

    2013-01-30

    Dilute oxalic acid pretreatment was applied to maple wood to improve compatibility with downstream operations, and its performance in pretreatment and subsequent enzymatic hydrolysis was compared to results for hydrothermal and dilute hydrochloric and sulfuric acid pretreatments. The highest total xylose yield of ∼84% of the theoretical maximum was for both 0.5% oxalic and sulfuric acid pretreatment at 160 °C, compared to ∼81% yield for hydrothermal pretreatment at 200 °C and for 0.5% hydrochloric acid pretreatment at 140 °C. The xylooligomer fraction from dilute oxalic acid pretreatment was only 6.3% of the total xylose in solution, similar to results with dilute hydrochloric and sulfuric acids but much lower than the ∼70% value for hydrothermal pretreatment. Combining any of the four pretreatments with enzymatic hydrolysis with 60 FPU cellulase/g of glucan plus xylan in the pretreated maple wood resulted in virtually the same total glucose plus xylose yields of ∼85% of the maximum possible.

  3. 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...

  4. Sulfur-based absolute quantification of proteins using isotope dilution inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lee, Hyun-Seok; Heun Kim, Sook; Jeong, Ji-Seon; Lee, Yong-Moon; Yim, Yong-Hyeon

    2015-10-01

    An element-based reductive approach provides an effective means of realizing International System of Units (SI) traceability for high-purity biological standards. Here, we develop an absolute protein quantification method using double isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS) combined with microwave-assisted acid digestion for the first time. We validated the method and applied it to certify the candidate protein certified reference material (CRM) of human growth hormone (hGH). The concentration of hGH was determined by analysing the total amount of sulfur in hGH. Next, the size-exclusion chromatography method was used with ICP-MS to characterize and quantify sulfur-containing impurities. By subtracting the contribution of sulfur-containing impurities from the total sulfur content in the hGH CRM, we obtained a SI-traceable certification value. The quantification result obtained with the present method based on sulfur analysis was in excellent agreement with the result determined via a well-established protein quantification method based on amino acid analysis using conventional acid hydrolysis combined with an ID liquid chromatography-tandem mass spectrometry. The element-based protein quantification method developed here can be generally used for SI-traceable absolute quantification of proteins, especially pure-protein standards.

  5. Sulfuric Acid in the Venus Clouds

    NASA Technical Reports Server (NTRS)

    Sill, G. T.

    1972-01-01

    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.

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

    PubMed

    Avci, Ayse; Saha, Badal C; Kennedy, Gregory J; Cotta, Michael A

    2013-08-01

    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 sugar yield. The optimal conditions for pretreatment of corn stover (10%, w/v) were: 0.75% H2SO4, 160°C, and 0-5 min holding time. The conditions were chosen based on maximum glucose release after enzymatic hydrolysis, minimum loss of pentose sugars and minimum formation of sugar degradation products such as furfural and hydroxymethyl furfural. The pretreated corn stover after enzymatic saccharification generated 63.2 ± 2.2 and 63.7 ± 2.3 g total sugars per L at 0 and 5 min holding time, respectively. Furfural production was 0.45 ± 0.1 and 0.87 ± 0.4 g/L, respectively. The recombinant Escherichia coli strain FBR5 efficiently fermented non-detoxified corn stover hydrolyzate if the furfural content is <0.5 g/L.

  7. 21 CFR 582.1095 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1095 Sulfuric acid. (a) Product. Sulfuric acid. (b) Conditions of use. This substance is...

  8. 21 CFR 582.1095 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1095 Sulfuric acid. (a) Product. Sulfuric acid. (b) Conditions of use. This substance is...

  9. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK....1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external...

  10. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK....1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external...

  11. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sulfuric acid. 184.1095 Section 184.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1095 Sulfuric acid. (a) Sulfuric acid (H2SO4, CAS Reg. No. 7664-93-9),...

  12. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK....1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external...

  13. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sulfuric acid. 184.1095 Section 184.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1095 Sulfuric acid. (a) Sulfuric acid (H2SO4, CAS Reg. No. 7664-93-9),...

  14. 21 CFR 582.1095 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1095 Sulfuric acid. (a) Product. Sulfuric acid. (b) Conditions of use. This substance is...

  15. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sulfuric acid. 184.1095 Section 184.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1095 Sulfuric acid. (a) Sulfuric acid (H2SO4, CAS Reg. No. 7664-93-9),...

  16. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sulfuric acid. 184.1095 Section 184.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1095 Sulfuric acid. (a) Sulfuric acid (H2SO4, CAS Reg. No. 7664-93-9),...

  17. 21 CFR 582.1095 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1095 Sulfuric acid. (a) Product. Sulfuric acid. (b) Conditions of use. This substance is...

  18. 21 CFR 184.1095 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sulfuric acid. 184.1095 Section 184.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1095 Sulfuric acid. (a) Sulfuric acid (H2SO4, CAS Reg. No. 7664-93-9), also known as oil of vitriol,...

  19. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK....1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external...

  20. 21 CFR 582.1095 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1095 Sulfuric acid. (a) Product. Sulfuric acid. (b) Conditions of use. This substance is...

  1. 46 CFR 153.1046 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK....1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external...

  2. Hydrate sulfuric acid after sulfur implantation in water ice

    NASA Astrophysics Data System (ADS)

    Strazzulla, G.; Baratta, G. A.; Leto, G.; Gomis, O.

    2007-12-01

    For many years an ongoing research program performed at our laboratory has had the aim to investigate the implantation of reactive ions in ices relevant to planetology by using IR spectroscopy. We present new results obtained by implanting 200 keV sulfur ions into water ice at 80 K. We have looked at the formation of sulfur-bearing molecules such as sulfuric acid, sulfur dioxide and hydrogen sulfide. We find that hydrated sulfuric acid is formed with high yield ( 0.65±0.1 molecules/ion). An upper limit to the production yield of SO 2 ( Y⩽0.025 molecules/ion) has been estimated; no hydrogen sulfide has been detected. The formation of hydrogen peroxide is confirmed. Ozone is not detected. The results are discussed relevant to the inquiry on the radiolytic sulfur cycle considered responsible for the formation of sulfur-bearing molecules on the surfaces of the Galilean satellites. We demonstrate that sulfur implantation efficiently forms hydrated sulfuric acid whose observed abundance is explained as caused by an exogenic process. It is more difficult to say if the observed sulfur dioxide is quantitatively supported by only sulfur implantation; additional experimental studies are necessary along with direct observations, especially at UV wavelengths such as those that could be performed by instruments on board Hubble Space Telescope or by the forthcoming World Space Observatory (WSO/UV).

  3. 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...

  4. 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.

  5. Charles H. Winston and Confederate Sulfuric Acid

    NASA Astrophysics Data System (ADS)

    Reithmiller, Steven

    1995-07-01

    Sulfuric acid turned out to be one of the critical chemicals made in the South during the Civil War. It was necessary for the manufacture of mercury fulminate which was used in the production of percussion caps and sulfuric acid was used in the Daniells cell to produce electricity. Charles H. Winston, president of the Richmond Female Institute and later professor at the University of Richmond (VA) was instrumental in the establishment of a plant to manufacture sulfuric acid in Charlotte, North Carolina. His patent and method of manufacture plus the uses of sulfuric acid during the Civil War are discussed.

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

    PubMed

    Chimentão, 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.

  7. Optimization of dilute acid hydrolysis of Enteromorpha

    NASA Astrophysics Data System (ADS)

    Feng, Dawei; Liu, Haiyan; Li, Fuchao; Jiang, Peng; Qin, Song

    2011-11-01

    Acid hydrolysis is a simple and direct way to hydrolyze polysaccharides in biomass into fermentable sugars. To produce fermentable sugars effectively and economically for fuel ethanol, we have investigated the hydrolysis of Enteromorpha using acids that are typically used to hydrolyze biomass: H2SO4, HCl, H3PO4 and C4H4O4 (maleic acid). 5%(w/w) Enteromorpha biomass was treated for different times (30, 60, and 90 min) and with different acid concentrations (0.6, 1.0, 1.4, 1.8, and 2.2%, w/w) at 121°C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars (glucose and xylose) was high, (230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose), with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.

  8. Sulfuric Acid Regeneration Waste Disposal Technology.

    DTIC Science & Technology

    1986-11-01

    46 2 4 H2 3 4 4 2 Phosphate Sulfuric Water Phosphoric Hydro- Phosphogypsum Rock Acid Acid fluoric Acid For our purposes the process could be viewed as...one where sulfuric acid is neutralized using phosphate rock rather than lime. Although the resulting calcium sulfate (referred to as phosphogypsum ...spearhead research in this country on uses for waste gypsum or phosphogypsum . They have published a recent review of historic and current work on

  9. Are the clouds of Venus sulfuric acid.

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1973-01-01

    It is shown that strong aqueous sulfuric acid solutions have the right refractive index and freeze at Venusian cloud temperature, explain the dryness of the Venusian stratosphere, are consistent with some features of the Venusian IR spectrum, and do not absorb in highly reflecting areas of Venus. It is also indicated that such solutions should be produced by reactions between known atmospheric constituents and most sulfur-bearing rock at the Venusian surface temperature, and require only small amounts of sulfur consistent with its cosmic abundance and with the amounts of other volatile elements present in the atmosphere. It is believed therefore that the clouds of Venus consist of sulfuric acid solutions.

  10. Reducing acid in dilute acid pretreatment and the impact on enzymatic saccharification.

    PubMed

    Chen, Ye; Stevens, Mark A; Zhu, Yongming; Holmes, Jason; Moxley, Geoffrey; Xu, Hui

    2012-05-01

    Dilute acid pretreatment is a leading pretreatment technology for biomass to ethanol conversion due to the comparatively low chemical cost and effective hemicellulose solubilization. The conventional dilute acid pretreatment processes use relatively large quantities of sulfuric acid and require alkali for pH adjustment afterwards. Significant amounts of sulfate salts are generated as by-products, which have to be properly treated before disposal. Wastewater treatment is an expensive, yet indispensable part of commercial level biomass-to-ethanol plants. Therefore, reducing acid use to the lowest level possible would be of great interest to the emerging biomass-to-ethanol industry. In this study, a dilute acid pretreatment process was developed for the pretreatment of corn stover. The pretreatment was conducted at lower acid levels than the conventional process reported in the literature while using longer residence times. The study indicates that a 50% reduction in acid consumption can be achieved without compromising pretreatment efficiency when the pretreatment time was extended from 1-5 min to 15-20 min. To avoid undesirable sugar degradation and inhibitor generation, temperatures should be controlled below 170°C. When the sulfuric acid-to-lignocellulosic biomass ratio was kept at 0.025 g acid/g dry biomass, a cellulose-to-glucose conversion of 72.7% can be achieved at an enzyme loading of 0.016 g/g corn stover. It was also found that acid loading based on total solids (g acid/g dry biomass) governs the pretreatment efficiency rather than the acid concentration (g acid/g pretreatment liquid). While the acid loading on lignocellulosic biomass may be achieved through various combinations of solids loading and acid concentration in the pretreatment step, this work shows that it is unlikely to reduce acid use without undermining pretreatment efficiency simply by increasing the solid content in pretreatment reactors, therefore acid loading on biomass is indicated

  11. Interaction of sulfuric acid corrosion and mechanical wear of iron

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Friction and wear experiments were conducted with elemental iron sliding on aluminum oxide in aerated sulfuric acid at concentrations ranging from very dilute (0.00007 N; i.e., 4 ppm) to very concentrated (96 percent acid). Load and reciprocating sliding speed were kept constant. With the most dilute acid concentration of 0.00007 to 0.0002 N, a complex corrosion product formed that was friable and often increased friction and wear. At slightly higher concentrations of 0.001 N, metal losses were essentially by wear alone. Because no buildup of corrosion products occurred, this acid concentration became the standard from which to separate metal loss from direct corrosion and mechanical wear losses. When the acid concentration was increased to 5 percent (1 N), the well-established high corrosion rate of iron in sulfuric acid strongly dominated the total wear loss. This strong corrosion increased to 30 percent acid and decreased somewhat to 50 percent acid in accordance with expectations. However, the low corrosion of iron expected at acid concentrations of 65 to 96 percent was not observed in the wear area. It was apparent that the normal passivating film was being worn away and a galvanic cell established that rapidly attacked the wear area. Under the conditions where direct corrosion losses were highest, the coefficient of friction was the lowest.

  12. Interaction of sulfuric acid corrosion and mechanical wear of iron

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Friction and wear experiment were conducted with elemental iron sliding on aluminum oxide in aerated sulfuric acid at concentrations ranging from very dilute (0.00007 N; i.e., 4 ppm) to very concentrated (96 percent acid). Load and reciprocating sliding speed were kept constant. With the most dilute acid concentration of 0.00007 to 0.0002 N, a complex corrosion product formed that was friable and often increased friction and wear. At slightly higher concentrations of 0.001 N, metal losses were essentially by wear alone. Because no buildup of corrosion products occurred, this acid concentration became the standard from which to separate metal loss from direct corrosion and mechanical wear losses. When the acid concentration was increased to 5 percent (1 N), the well-established high corrosion rate of iron in sulfuric acid strongly dominated the total wear loss. This strong corrosion increased to 30 percent acid and decreased somewhat to 50 percent acid in accordance with expectations. However, the low corrosion of iron expected at acid concentrations of 65 to 96 percent was not observed in the wear area. It was apparent that the normal passivating film was being worn away and a galvanic cell established that rapidly attacked the wear area. Under the conditions where direct corrosion losses were highest, the coefficient of friction was the lowest.

  13. Commercial Alloys for Sulfuric Acid Vaporization in Thermochemical Hydrogen Cycles

    SciTech Connect

    Thomas M. Lillo; Karen M. Delezene-Briggs

    2005-10-01

    Most thermochemical cycles being considered for producing hydrogen include a processing stream in which dilute sulfuric acid is concentrated, vaporized and then decomposed over a catalyst. The sulfuric acid vaporizer is exposed to highly aggressive conditions. Liquid sulfuric acid will be present at a concentration of >96 wt% (>90 mol %) H2SO4 and temperatures exceeding 400oC [Brown, et. al, 2003]. The system will also be pressurized, 0.7-3.5 MPa, to keep the sulfuric acid in the liquid state at this temperature and acid concentration. These conditions far exceed those found in the commercial sulfuric acid generation, regeneration and handling industries. Exotic materials, e.g. ceramics, precious metals, clad materials, etc., have been proposed for this application [Wong, et. al., 2005]. However, development time, costs, reliability, safety concerns and/or certification issues plague such solutions and should be considered as relatively long-term, optimum solutions. A more cost-effective (and relatively near-term) solution would be to use commercially-available metallic alloys to demonstrate the cycle and study process variables. However, the corrosion behavior of commercial alloys in sulfuric acid is rarely characterized above the natural boiling point of concentrated sulfuric acid (~250oC at 1 atm). Therefore a screening study was undertaken to evaluate the suitability of various commercial alloys for concentration and vaporization of high-temperature sulfuric acid. Initially alloys were subjected to static corrosion tests in concentrated sulfuric acid (~95-97% H2SO4) at temperatures and exposure times up to 200oC and 480 hours, respectively. Alloys with a corrosion rate of less than 5 mm/year were then subjected to static corrosion tests at a pressure of 1.4 MPa and temperatures up to 375oC. Exposure times were shorter due to safety concerns and ranged from as short as 5 hours up to 144 hours. The materials evaluated included nickel-, iron- and cobalt

  14. Friction and wear of iron in sulfuric acid

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Elemental iron sliding on aluminum oxide in aerated sulfuric acid concentrations ranging from very dilute (0.000007 N; i.e., 4 ppm) to very concentrated (96 percent acid) was studied. Load and reciprocating sliding speeds were kept constant. With the most dilute acid of 0.7 to 0.0002 N, a complex corrosion product formed that was friable and often increased friction and wear. At concentrations of 0.001 N, metal losses were essentially by wear alone. Because no buildup of corrosion products occurred, this acid concentration became the standard from which to separate metal loss from direct corrosion and mechanical wear losses. When the acid concentration was increased to 5 percent, the high corrosion rate of iron in sulfuric acid strongly dominated the total wear loss. This strong corrosion increased to 30 percent acid, and decreased somewhat at 50 percent in accordance with expectations. However, the low corrosion of iron expected at acid concentrations of 65 to 96 percent was not observed in the wear area. It is apparent that the normal passivating film was being worn away and a galvanic cell established which rapidly attached to the wear area.

  15. Dilute acid/metal salt hydrolysis of lignocellulosics

    DOEpatents

    Nguyen, Quang A.; Tucker, Melvin P.

    2002-01-01

    A modified dilute acid method of hydrolyzing the cellulose and hemicellulose in lignocellulosic material under conditions to obtain higher overall fermentable sugar yields than is obtainable using dilute acid alone, comprising: impregnating a lignocellulosic feedstock with a mixture of an amount of aqueous solution of a dilute acid catalyst and a metal salt catalyst sufficient to provide higher overall fermentable sugar yields than is obtainable when hydrolyzing with dilute acid alone; loading the impregnated lignocellulosic feedstock into a reactor and heating for a sufficient period of time to hydrolyze substantially all of the hemicellulose and greater than 45% of the cellulose to water soluble sugars; and recovering the water soluble sugars.

  16. High temperature dilute acid pretreatment of coastal Bermuda grass for enzymatic hydrolysis.

    PubMed

    Redding, Arthur P; Wang, Ziyu; Keshwani, Deepak R; Cheng, Jay J

    2011-01-01

    Dilute sulfuric acid was used to pretreat coastal Bermuda grass at high temperature prior to enzymatic hydrolysis. After both pretreatment and enzymatic hydrolysis processes, the highest yield of total sugars (combined xylose and glucose) was 97% of the theoretical value. The prehydrolyzate liquor was analyzed for inhibitory compounds (furfural, hydroxymethylfurfural (HMF)) in order to assess potential risk for inhibition during the following fermentation. Accounting for the formation of the inhibitory compounds, a pretreatment with 1.2% acid at 140 °C for 30 min with a total sugar yield of 94% of the theoretical value may be more favorable for fermentation. From this study, it can be concluded that dilute sulfuric acid pretreatment can be successfully applied to coastal Bermuda grass to achieve high yields of monomeric glucose and xylose with acceptable levels of inhibitory compound formation.

  17. 46 CFR 151.50-21 - Sulfuric acid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid of concentration of 77.5 percent (1.7019 specific gravity)...

  18. 46 CFR 151.50-21 - Sulfuric acid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid of concentration of 77.5 percent (1.7019 specific gravity)...

  19. 46 CFR 151.50-21 - Sulfuric acid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid of concentration of 77.5 percent (1.7019 specific gravity)...

  20. 46 CFR 151.50-21 - Sulfuric acid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid of concentration of 77.5 percent (1.7019 specific gravity)...

  1. 46 CFR 151.50-21 - Sulfuric acid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid of concentration of 77.5 percent (1.7019 specific gravity)...

  2. Infrared spectroscopy of sulfuric acid/water aerosols: Freezing characteristics

    NASA Astrophysics Data System (ADS)

    Clapp, M. L.; Niedziela, R. F.; Richwine, L. J.; Dransfield, T.; Miller, R. E.; Worsnop, D. R.

    1997-04-01

    A low-temperature flow cell has been used in conjunction with a Fourier transform infrared (FT-IR) spectrometer to study sulfuric acid/water aerosols. The aerosols were generated with a wide range of composition (28 to 85 wt%), including those characteristic of stratospheric sulfate aerosols, and studied over the temperature range from 240 K to 160 K. The particles exhibited deep supercooling, by as much as 100 K below the freezing point in some cases. Freezing of water ice was observed in the more dilute (<40 wt% sulfuric acid) particles, in agreement with the predictions of Jensen et al. and recent observations by Bertram et al. In contrast with theoretical predictions, however, the entire particle often does not immediately freeze, at least on the timescale of the present experiments (seconds to minutes). Freezing of the entire particle is observed at lower temperatures, well below that characteristic of the polar stratosphere.

  3. Methane activation and oxidation in sulfuric acid.

    PubMed

    Goeppert, Alain; Dinér, Peter; Ahlberg, Per; Sommer, Jean

    2002-07-15

    The H/D exchange observed when methane is contacted with D(2)SO(4) at 270-330 degrees C shows that the alkane behaves as a sigma base and undergoes rapid and reversible protonation at this temperature. DFT studies of the hydrogen exchange between a monomer and a dimer of sulfuric acid and methane show that the transition states involved in the exchange are bifunctional, that is one hydrogen atom is transferred from a hydroxy group in sulfuric acid to methane, while one hydrogen atom is abstracted from methane by a non-hydroxy oxygen atom in sulfuric acid. All the transition states include a CH(5) moiety, which shows similarities to the methanium ion CH(5) (+). The calculated potential activation energy of the hydrogen exchange for the monomer is 174 kJ mol(-1), which is close to the experimental value (176 kJ mol(-1)). Solvation of the monomer and the transition state of the monomer with an extra sulfuric acid molecule, decrease the potential activation energy by 6 kJ mol(-1). The acid-base process is in competition, however, with an oxidative process involving methane and sulfuric acid which leads to CO(2), SO(2), and water, and thus to a decrease of acidity and loss of reactivity of the medium.

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

    SciTech Connect

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

    1997-11-01

    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 of 30 C and an initial pH of 5.5. The fermentabilities were quite different for the different wood species, and only hydrolyzates of spruce produced at 188 and 198 C, hydrolyzates of pine produced at 188 C, and hydrolyzates of willow produced at 198 C could be completely fermented within 24 h. From the sum of the concentrations of the known inhibitors furfural and 5-(hydroxymethyl)furfural (HMF), a good prediction of the maximum ethanol production rate could be obtained, regardless of the origin of the hydrolyzate. Furthermore, in hydrolyzates that fermented well, furfural and HMF were found to be taken up and converted by the yeast, concomitant with the uptake of glucose.

  5. Enzymatic saccharification of dilute acid pretreated eucalyptus chips for fermentable sugar production.

    PubMed

    Wei, Weiqi; Wu, Shubin; Liu, Liguo

    2012-04-01

    Dilute sulfuric acid was used to pretreat eucalyptus chips prior to enzymatic hydrolysis. After both pretreatment and enzymatic hydrolysis processes. Attention is paid to sugar recovery. The maximum total sugars yield (combined xylose and glucose, 47.69g/100g raw material, representing 82% of total sugars in the eucalyptus biomass) was obtained at 160°C, 0.75% acid concentration and 10min residence time, which is consider to be the best reasonable conditions for the dilute acid pretreatment of eucalyptus, corresponding concentrations of acetic acid, HMF, and furfural in the prehydrolysate were about 2.01g/L, 0.13g/L and 1.37g/L, respectively. Under this optimal pretreatment condition, the acid-insoluble lignin recovery in the insoluble solid resulting from enzymatic hydrolysis, was 22.7g/100g raw material, representing 80% of acid-insoluble lignin in the eucalyptus biomass.

  6. 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.

  7. 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.

  8. 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.

  9. Two-stage dilute acid prehydrolysis of biomass

    DOEpatents

    Grohmann, Karel; Torget, Robert W.

    1992-01-01

    A two-stage dilute acid prehydrolysis process on xylan containing hemicellulose in biomass is effected by: treating feedstock of hemicellulosic material comprising xylan that is slow hydrolyzable and xylan that is fast hydrolyzable under predetermined low temperature conditions with a dilute acid for a residence time sufficient to hydrolyze the fast hydrolyzable xylan to xylose; removing said xylose from said fast hydrolyzable xylan and leaving a residue; and treating said residue having a slow hydrolyzable xylan with a dilute acid under predetermined high temperature conditions for a residence time required to hydrolyze said slow hydrolyzable xylan to xylose.

  10. Comparing the performance of Miscanthus x giganteus and wheat straw biomass in sulfuric acid based pretreatment.

    PubMed

    Kärcher, M A; Iqbal, Y; Lewandowski, I; Senn, T

    2015-03-01

    The objective of this study was to assess and compare the suitability of Miscanthus x giganteus and wheat straw biomass in dilute acid catalyzed pretreatment. Miscanthus and wheat straw were treated in a dilute sulfuric acid/steam explosion pretreatment. As a result of combining dilute sulfuric acid- and steam explosion pretreatment the hemicellulose hydrolysis yields (96% in wheat straw and 90% in miscanthus) in both substrates were higher than reported in literature. The combined severity factor (=CSF) for optimal hemicellulose hydrolysis was 1.9 and 1.5 in for miscanthus and wheat straw respectively. Because of the higher CSF value more furfural, furfuryl alcohol, 5-hydroxymethylfurfural and acetic acid was formed in miscanthus than in wheat straw pretreatment.

  11. Sulfur

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    In 2011, elemental sulfur and the byproduct sulfuric acid were produced at 109 operations in 29 states and the U.S. Virgin Islands. Total shipments were valued at about $1.6 billion. Elemental sulfur production was 8.2 Mt (9 million st); Louisiana and Texas accounted for about 53 percent of domestic production.

  12. Intestinal metabolism of sulfur amino acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acid (SAA) metabolism in the body and metabolizes approx. 20% of the dietary methionine intake that is mainly transmethylated to homocysteine and transsulfurated to cysteine. The GIT accounts for approx. 25% of the ...

  13. Charles H. Winston and Confederate Sulfuric Acid.

    ERIC Educational Resources Information Center

    Riethmiller, Steven

    1995-01-01

    Describes the invention and use of a sulfuric acid chamber by Charles Henry Winston during the Civil War. This invention helped supply munitions for the South. Winston, who was President of the Richmond Female Institute in Virginia, constructed the chamber at his farm and was granted a patent by the Confederate Patent Office in 1863. (PVD)

  14. Sulfuric acid thermoelectrochemical system and method

    DOEpatents

    Ludwig, Frank A.

    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.

  15. The influence of ferrous sulfate utilization on the sugar yields from dilute-acid pretreatment of softwood for bioethanol production.

    PubMed

    Monavari, Sanam; Galbe, Mats; Zacchi, Guido

    2011-01-01

    By employing metal salts in dilute-acid pretreatment the severity can be reduced due to reduced activation energy. This study reports on a dilute-acid steam pretreatment of spruce chips by addition of a small amount of ferrous sulfate to the acid catalyst, i.e., either SO2, H2SO3 or H2SO4. The utilization of ferrous sulfate resulted in a slightly increased overall glucose yield (from 74% to 78% of the theoretical value) in pretreatment with SO2 and H2SO3. Impregnation with ferrous sulfate and sulfuric acid did not give any improvement compared with pretreatment based solely on H2SO4.

  16. Heterogeneous Interaction of Peroxyacetyl Nitrate on Liquid Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun

    1996-01-01

    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.

  17. Comparison of cell wall polysaccharide hydrolysis by a dilute acid/enzymatic saccharification process and rumen microorganisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of biomass crops for breeding or pricing purposes requires an assay that predicts performance of biomass in the bioenergy conversion process. Cell wall polysaccharide hydrolysis by dilute sulfuric acid pretreatment at 121 degrees C followed by cellulase hydrolysis for 72 h (CONV) and in v...

  18. 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

    2014-01-02

    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.

  19. Boric/sulfuric acid anodize - Alternative to chromic acid anodize

    NASA Astrophysics Data System (ADS)

    Koop, Rodney; Moji, Yukimori

    1992-04-01

    The suitability of boric acid/sulfuric acid anodizing (BSAA) solution as a more environmentally acceptable replacement of the chromic acid anodizing (CAA) solution was investigated. Results include data on the BSAA process optimization, the corrosion protection performance, and the compatibility with aircraft finishing. It is shown that the BSSA implementation as a substitude for CAA was successful.

  20. Long term storage of dilute acid pretreated corn stover feedstock and ethanol fermentability evaluation.

    PubMed

    Zhang, Jian; Shao, Shuai; Bao, Jie

    2016-02-01

    This study reported a new solution of lignocellulose feedstock storage based on the distributed pretreatment concept. The dry dilute sulfuric acid pretreatment (DDAP) was conducted on corn stover feedstock, instead of ammonia fiber explosion pretreatment. Then the dry dilute acid pretreated corn stover was stored for three months during summer season with high temperature and humidity. No negative aspects were found on the physical property, composition, hydrolysis yield and ethanol fermentability of the long term stored pretreated corn stover, plus the additional merits including no chemicals recovery operation, anti-microbial contaminant environment from stronger acid and inhibitor contents, as well as the mild and slow hydrolysis in the storage. The new pretreatment method expanded the distributed pretreatment concept of feedstock storage with potential for practical application.

  1. A comparison of chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Because of federal and state mandates restricting the use of hexavalent chromium, it was deemed worthwhile to compare the corrosion protection afforded 2219-T87 aluminum alloy by both Type I chromic acid and Type II sulfuric acid anodizing per MIL-A-8625. Corrosion measurements were made on large, flat 2219-T87 aluminum alloy sheet material with an area of 1 cm(exp 2) exposed to a corrosive medium of 3.5-percent sodium chloride at pH 5.5. Both ac electrochemical impedance spectroscopy and the dc polarization resistance techniques were employed. The results clearly indicate that the corrosion protection obtained by Type II sulfuric acid anodizing is superior, and no problems should result by substituting Type II sulfuric acid anodizing for Type I chromic acid anodizing.

  2. Exposure to sulfuric acid in zinc production.

    PubMed

    Bråtveit, Magne; Haaland, Inger Margrethe; Moen, Bente E; Målsnes, Agnar

    2004-03-01

    This study characterized workers' exposure to sulfuric acid in two cell houses of a zinc production plant. We also aimed at estimating previous exposure to sulfuric acid by simulating the process conditions from before 1975 to produce exposure data for an epidemiological study on cancer in this industry. Further, we compared different sampling methods for aerosols in the cell houses. Personal sampling with a 37 mm Millipore cassette showed that the geometric means of the exposure levels for the workers in the two cell houses were 0.07 mg/m3 (range 0.01-0.48 mg/m3) and 0.04 mg/m3 (range 0.01-0.15 mg/m3). Norway's newly revised limit value of 0.1 mg/m3 was exceeded in 39.0 and 12.9% of the samples in the two cell houses. After the foam layer was removed from the electrolyte surface to simulate the production process from before 1975, the concentration of sulfuric acid increased from 0.11 to 6.04 mg/m3 in stationary measurement by the Millipore sampler. Stationary sampling showed that the Millipore sampler and the inhalable fraction of the Respicon impactor underestimated the sulfuric acid concentration by factors of 1.5 and 2.1 compared with the Institute of Occupational Medicine (IOM) sampler. Sampling with the Respicon impactor showed that the respirable, tracheobronchial and extrathoracic fractions constituted 3.0, 18.7 and 71.7% of the inhalable sulfuric acid aerosol, respectively. Today's exposure levels are lower than those reported to be associated with an increased prevalence of laryngeal cancer in other industries, but the levels prior to 1975 seem to have been much higher. By mass, most of the inhalable aerosol was in the size fractions considered to be highly relevant for the effects of sulfuric acid on the respiratory system. The risk of cancer among the cell house workers should be investigated in an epidemiological study.

  3. Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2006-01-01

    We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

  4. Fermentative production of high titer citric acid from corn stover feedstock after dry dilute acid pretreatment and biodetoxification.

    PubMed

    Zhou, Ping-Ping; Meng, Jiao; Bao, Jie

    2017-01-01

    The aim of this work is to study the citric acid fermentation by a robust strain Aspergillus niger SIIM M288 using corn stover feedstock after dry dilute sulfuric acid pretreatment and biodetoxification. Citric acid at 100.04g/L with the yield of 94.11% was obtained, which are comparable to the starch or sucrose based citric acid fermentation. No free wastewater was generated in the overall process from the pretreatment to citric acid fermentation. Abundant divalent metal ions as well as high titer of potassium, phosphate, and nitrogen were found in corn stover hydrolysate. Further addition of extra nutrients showed no impact on increasing citric acid formation except minimum nitrogen source was required. Various fermentation parameters were tested and only minimum regulation was required during the fermentation. This study provided a biorefining process for citric acid fermentation from lignocellulose feedstock with the maximum citric acid titer and yield.

  5. 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.

  6. Isotope dilution ICP-MS with laser-assisted sample introduction for direct determination of sulfur in petroleum products.

    PubMed

    Boulyga, Sergei F; Heilmann, Jens; Heumann, Klaus G

    2005-08-01

    Inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with direct laser-assisted introduction of isotope-diluted samples into the plasma, using a laser ablation system with high ablation rates, was developed for accurate sulfur determinations in different petroleum products such as 'sulfur-free' premium gasoline, diesel fuel, and heating oil. Two certified gas oil reference materials were analyzed for method validation. Two different 34S-enriched spike compounds, namely, elementary sulfur dissolved in xylene and dibenzothiophene in hexane, were synthesized and tested for their usefulness in this isotope dilution technique. The isotope-diluted sample was adsorbed on a filter-paper-like material, which was fixed in a special holder for irradiation by the laser beam. Under these conditions no time-dependent spike/analyte fractionation was only observed for the dibenzothiophene spike during the laser ablation process, which means that the measured 34S/32S isotope ratio of the isotope-diluted sample remained constant-a necessary precondition for accurate results with the isotope dilution technique. A comparison of LA-ICP-IDMS results with the certified values of the gas oil reference materials and with results obtained from ICP-IDMS analyses with wet sample digestion demonstrated the accuracy of the new LA-ICP-IDMS method in the concentration range of 9.2 microg g(-1) ('sulfur-free' premium gasoline) to 10.4 mg g(-1) (gas oil reference material BCR 107). The detection limit for sulfur by LA-ICP-IDMS is 0.04 microg g(-1) and the analysis time is only about 10 min, which therefore also qualifies this method for accurate determinations of low sulfur contents in petroleum products on a routine level.

  7. Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium

    ERIC Educational Resources Information Center

    Romero, Alicia; Hernandez, Willie; Suarez, Marco F.

    2005-01-01

    The effect of some parameters on sulfurous acid and sulfur oxidation kinetics such as initial concentration of sulfurous acid, oxygen, TiO[2] crystalline concentration, the power of black light, and quantity of TiO[2] is investigated. The experiments can be performed in an undergraduate physical chemistry laboratory with an inexpensive…

  8. FTIR studies of low temperature sulfuric acid aerosols

    NASA Technical Reports Server (NTRS)

    Anthony, S. E.; Tisdale, R. T.; Disselkamp, R. S.; Tolbert, M. A.; Wilson, J. C.

    1995-01-01

    Sub-micrometer sized sulfuric acid H2SO4 particles were generated using a constant output atomizer source. The particles were then exposed to water vapor before being injected into a low temperature cell. Multipass transmission Fourier Transformation Infrared (FTIR) spectroscopy was used to determine the phase and composition of the aerosols as a function of time for periods of up to five hours. Binary H2SO4H2O aerosols with compositions from 35 to 95 wt % H2SO4 remained liquid for over 3 hours at room temperatures ranging from 189-240 K. These results suggest that it is very difficut to freeze SSAs via homogeneous nucleation. Attempts to form aerosols more dilute than 35 wt % H2SO4 resulted in ice formation.

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

    SciTech Connect

    Jolley-Souders, K.; Geib, R.; Dunn, C.

    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.

  10. Ethanol production with dilute acid hydrolysis using partially dried lignocellulosics

    DOEpatents

    Nguyen, Quang A.; Keller, Fred A.; Tucker, Melvin P.

    2003-12-09

    A process of converting lignocellulosic biomass to ethanol, comprising hydrolyzing lignocellulosic materials by subjecting dried lignocellulosic material in a reactor to a catalyst comprised of a dilute solution of a strong acid and a metal salt to lower the activation energy (i.e., the temperature) of cellulose hydrolysis and ultimately obtain higher sugar yields.

  11. Optimization of dilute acid pretreatment of water hyacinth biomass for enzymatic hydrolysis and ethanol production

    PubMed Central

    Idrees, Muhammad; Adnan, Ahmad; Sheikh, Shahzad; Qureshic, Fahim Ashraf

    2013-01-01

    The present study was conducted for the optimization of pretreatment process that was used for enzymatic hydrolysis of lignocellulosic biomass (Water Hyacinth, WH), which is a renewable resource for the production of bioethanol with decentralized availability. Response surface methodology has been employed for the optimization of temperature (oC), time (hr) and different concentrations of maleic acid (MA), sulfuric acid (SA) and phosphoric acid (PA) that seemed to be significant variables with P < 0.05. High F and R2 values and low P-value for hydrolysis yield indicated the model predictability. The pretreated biomass producing 39.96 g/l, 39.86 g/l and 37.9 g/l of reducing sugars during enzymatic hydrolysis with yield 79.93, 78.71 and 75.9 % from PA, MA and SA treated respectively. The order of catalytic effectiveness for hydrolysis yield was found to be phosphoric acid > maleic acid > sulfuric acid. Mixture of sugars was obtained during dilute acid pretreatment with glucose being the most prominent sugar while pure glucose was obtained during enzymatic hydrolysis. The resulting sugars, obtained during enzymatic hydrolysis were finally fermented to ethanol, with yield 0.484 g/g of reducing sugars which is 95 % of theoretical yield (0.51 g/g glucose) by using commercial baker's yeast (Sacchromyces cerveasiae). PMID:26417215

  12. Optimization of dilute acid pretreatment of water hyacinth biomass for enzymatic hydrolysis and ethanol production.

    PubMed

    Idrees, Muhammad; Adnan, Ahmad; Sheikh, Shahzad; Qureshic, Fahim Ashraf

    2013-01-01

    The present study was conducted for the optimization of pretreatment process that was used for enzymatic hydrolysis of lignocellulosic biomass (Water Hyacinth, WH), which is a renewable resource for the production of bioethanol with decentralized availability. Response surface methodology has been employed for the optimization of temperature ((o)C), time (hr) and different concentrations of maleic acid (MA), sulfuric acid (SA) and phosphoric acid (PA) that seemed to be significant variables with P < 0.05. High F and R (2) values and low P-value for hydrolysis yield indicated the model predictability. The pretreated biomass producing 39.96 g/l, 39.86 g/l and 37.9 g/l of reducing sugars during enzymatic hydrolysis with yield 79.93, 78.71 and 75.9 % from PA, MA and SA treated respectively. The order of catalytic effectiveness for hydrolysis yield was found to be phosphoric acid > maleic acid > sulfuric acid. Mixture of sugars was obtained during dilute acid pretreatment with glucose being the most prominent sugar while pure glucose was obtained during enzymatic hydrolysis. The resulting sugars, obtained during enzymatic hydrolysis were finally fermented to ethanol, with yield 0.484 g/g of reducing sugars which is 95 % of theoretical yield (0.51 g/g glucose) by using commercial baker's yeast (Sacchromyces cerveasiae).

  13. Recovery of very dilute acetic acid using ion exchange

    SciTech Connect

    Cloete, F.L.D.; Marais, A.P.

    1995-07-01

    Acetic and related acids occur in many industrial wastewaters, often mixed with several other classes of organic compounds. Acetic acid can be recovered from 1% solutions using weakly basic ion exchange resins. The acid is adsorbed by the free-base form of the resin, which can then be eluted using a slurry of lime to give a solution of calcium acetate. This solution could either be evaporated to crystallize calcium acetate or reacted with sulfuric acid to form acetic acid and gypsum. Laboratory tests of the proposed process gave product solutions of 15--20% acetic acid using pure 1% acetic acid as feed. Some measurements using a typical industrial effluent gave similar recoveries and showed that there was no initial fouling of the resins.

  14. 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.

  15. A sulfuric-lactic acid process for efficient purification of fungal chitosan with intact molecular weight.

    PubMed

    Naghdi, Mitra; Zamani, Akram; Karimi, Keikhosro

    2014-02-01

    The most recent method of fungal chitosan purification, i.e., two steps of dilute sulfuric acid treatment, pretreatment of cell wall at room temperature for phosphate removal and extraction of chitosan from the phosphate free cell wall at high temperature, significantly reduces the chitosan molecular weight. This study was aimed at improvement of this method. In the pretreatment step, to choose the best conditions, cell wall of Rhizopus oryzae, containing 9% phosphate, 10% glucosamine, and 21% N-acetyl glucosamine, was treated with sulfuric, lactic, acetic, nitric, or hydrochloric acid, at room temperature. Sulfuric acid showed the best performance in phosphate removal (90%) and cell wall recovery (89%). To avoid depolymerisation of chitosan, hot sulfuric acid extraction was replaced with lactic acid treatment at room temperature, and a pure fungal chitosan was obtained (0.12 g/g cell wall). Similar pretreatment and extraction processes were conducted on pure shrimp chitosan and resulted in a chitosan recovery of higher than 87% while the reduction of chitosan viscosity was less than 15%. Therefore, the sulfuric-lactic acid method purified the fungal chitosan without significant molecular weight manipulation.

  16. Sulfuric acid nucleation: An experimental study of the effect of seven bases

    NASA Astrophysics Data System (ADS)

    Glasoe, W. A.; Volz, K.; Panta, B.; Freshour, N.; Bachman, R.; Hanson, D. R.; McMurry, P. H.; Jen, C.

    2015-03-01

    Nucleation of particles with sulfuric acid, water, and nitrogeneous bases was studied in a flow reactor. Sulfuric acid and water levels were set by flows over sulfuric acid and water reservoirs, respectively, and the base concentrations were determined from measured permeation rates and flow dilution ratios. Particle number distributions were measured with a nano-differential-mobility-analyzer system. Results indicate that the nucleation capability of NH3, methylamine, dimethylamine, and trimethylamine with sulfuric acid increases from NH3 as the weakest, methylamine next, and dimethylamine and trimethylamine the strongest. Three other bases were studied, and experiments with triethylamine showed that it is less effective than methylamine, and experiments with urea and acetamide showed that their capabilities are much lower than the amines with acetamide having basically no effect. When both NH3 and an amine were present, nucleation was more strongly enhanced than with just the amine present. Comparisons of nucleation rates to predictions and previous experimental work are discussed, and the sulfuric acid-base nucleation rates measured here are extrapolated to atmospheric conditions. The measurements suggest that atmospheric nucleation rates are significantly affected by synergistic interactions between ammonia and amines.

  17. 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.

  18. Characterization of lignin derived from water-only and dilute acid flowthrough pretreatment of poplar wood at elevated temperatures

    SciTech Connect

    Zhang, Libing; Yan, Lishi; Wang, Zheming; Laskar, Dhrubojyoti D.; Swita, Marie S.; Cort, John R.; Yang, Bin

    2015-12-01

    In this study, flowthrough pretreatment of biomass has high potential to valorize lignin derivatives to high-value products, which is vital to enhance the economy of biorefinery plants. Comprehensive understanding of lignin behaviors and solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of providing flexible platform for lignin utilization. In this study, the effects of flowthrough pretreatment conditions on lignin separation from poplar wood were reported as well as the characteristics of three sub-sets of lignin produced from the pretreatment, including residual lignin in pretreated solid residues (ReL), recovered insoluble lignin in pretreated liquid (RISL), and recovered soluble lignin in pretreatment liquid (RSL). Both the water-only and 0.05% (w/w) sulfuric acid pretreatments were performed at temperatures from 160 to 270°C on poplar wood in a flowthrough reactor system for 2-10 min. Results showed that water-only flowthrough pretreatment primarily removed syringyl (S units). Increased temperature and/or the addition of sulfuric acid enhanced the removal of guaiacyl (G units) compared to water-only pretreatments at lower temperatures, resulting in nearly complete removal of lignin from the biomass. Results also suggested that more RISL was recovered than ReL and RSL in both dilute acid and water-only flowthrough pretreatment at elevated temperatures. NMR spectra of the RISL revealed significant β-O-4 cleavage, α-β deoxygenation to form cinnamyl-like end groups, and slight β-5 repolymerization in both water-only and dilute acid flowthrough pretreatments. In conclusion, elevated temperature and/or dilute acid greatly enhanced lignin removal to almost 100% by improving G unit removal besides S unit removal in flowthrough system. A new lignin chemistry transformation pathway was proposed and revealed the complexity of lignin structural change during

  19. 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).

  20. Limits for alkaline detoxification of dilute-acid lignocellulose hydrolysates.

    PubMed

    Nilvebrant, Nils-Olof; Persson, Per; Reimann, Anders; De Sousa, Filipe; Gorton, Lo; Jönsson, Leif J

    2003-01-01

    In addition to fermentable sugars, dilute-acid hydrolysates of lignocellulose contain compounds that inhibit fermenting microorganisms, such as Saccharomyces cerevisiae. Previous results show that phenolic compounds and furan aldehydes, and to some extent aliphatic acids, act as inhibitors during fermentation of dilute-acid hydrolysates of spruce. Treatment of lignocellulose hydrolysates with alkali, usually in the form of overliming to pH 10.0, has been frequently employed as a detoxification method to improve fermentability. A spruce dilute-acid hydrolysate was treated with NaOH in a factorial design experiment, in which the pH was varied between 9.0 and 12.0, the temperature between 5 and 80 degrees C, and the time between 1 and 7 h. Already at pH 9.0, >25% of the glucose was lost when the hydrolysate was treated at 80 degrees C for 1 h. Among the monosaccharides, xylose was degraded faster under alkaline conditions than the hexoses (glucose, mannose, and galactose), which, in turn, were degraded faster than arabinose. The results suggest that alkali treatment of hydrolysates can be performed at temperatures below 30 degrees C at any pH between 9.0 and 12.0 without problems with sugar degradation or formation of inhibiting aliphatic acids. Treatment with Ca(OH)2 instead of NaOH resulted in more substantial degradation of sugars. Under the harsher conditions of the factorial design experiment, the concentrations of furfural and 5-hydroxymethylfurfural decreased while the total phenolic content increased. The latter phenomenon was tentatively attributed to fragmentation of soluble aromatic oligomers in the hydrolysate. Separate phenolic compounds were affected in different ways by the alkaline conditions with some compounds showing an increase in concentration while others decreased. In conclusion, the conditions used for detoxification with alkali should be carefully controlled to optimize the positive effects and minimize the degradation of fermentable sugars.

  1. Effect of dilute acid pretreatment on the conversion of barley straw with grains to fermentable sugars.

    PubMed

    Yang, Ming; Kuittinen, Suvi; Zhang, Junhua; Keinänen, Markku; Pappinen, Ari

    2013-10-01

    This study investigated the effects of pretreatment conditions, dilute sulfuric acid concentration and treatment time, on the carbohydrate solubility of a mixture of barley straw and grain. The conditions were expressed as combined severity (CS) to evaluate sugar recovery from pretreated samples. Enzymatic hydrolysates from the lignocellulose pretreatment residues were also included to the results. CS was positively correlating with glucose recovery in all conditions, but in higher acid concentrations CS did not predict xylose recovery. It appeared that the residual xylan better indicate the xylose release. An optimal fermentable sugar yield from the mixture of barley straw and grain was obtained by maintaining the CS at around 1.38, corresponding to an overall glucose yield of 96% and a xylose yield of 57%.

  2. Ethanol production from industrial hemp: effect of combined dilute acid/steam pretreatment and economic aspects.

    PubMed

    Kuglarz, Mariusz; Gunnarsson, Ingólfur B; Svensson, Sven-Erik; Prade, Thomas; Johansson, Eva; Angelidaki, Irini

    2014-07-01

    In the present study, combined steam (140-180°C) and dilute-acid pre-hydrolysis (0.0-2.0%) were applied to industrial hemp (Cannabis sativa L.), as pretreatment for lignocellulosic bioethanol production. The influence of the pretreatment conditions and cultivation type on the hydrolysis and ethanol yields was also evaluated. Pretreatment with 1% sulfuric acid at 180°C resulted in the highest glucose yield (73-74%) and ethanol yield of 75-79% (0.38-0.40 g-ethanol/g-glucose). Taking into account the costs of biomass processing, from field to ethanol facility storage, the field-dried hemp pretreated at the optimal conditions showed positive economic results. The type of hemp cultivation (organic or conventional) did not influence significantly the effectiveness of the pretreatment as well as subsequent enzymatic hydrolysis and ethanol fermentation.

  3. Optimization of the dilute maleic acid pretreatment of wheat straw

    PubMed Central

    2009-01-01

    Background In this study, the dilute maleic acid pretreatment of wheat straw is optimized, using pretreatment time, temperature and maleic acid concentration as design variables. A central composite design was applied to the experimental set up. The response factors used in this study are: (1) glucose benefits from improved enzymatic digestibility of wheat straw solids; (2) xylose benefits from the solubilization of xylan to the liquid phase during the pretreatment; (3) maleic acid replenishment costs; (4) neutralization costs of pretreated material; (5) costs due to furfural production; and (6) heating costs of the input materials. For each response factor, experimental data were fitted mathematically. After data translation to €/Mg dry straw, determining the relative contribution of each response factor, an economic optimization was calculated within the limits of the design variables. Results When costs are disregarded, an almost complete glucan conversion to glucose can be reached (90% from solids, 7%-10% in liquid), after enzymatic hydrolysis. During the pretreatment, up to 90% of all xylan is converted to monomeric xylose. Taking cost factors into account, the optimal process conditions are: 50 min at 170°C, with 46 mM maleic acid, resulting in a yield of 65 €/Mg (megagram = metric ton) dry straw, consisting of 68 €/Mg glucose benefits (from solids: 85% of all glucan), 17 €/Mg xylose benefits (from liquid: 80% of all xylan), 17 €/Mg maleic acid costs, 2.0 €/Mg heating costs and 0.68 €/Mg NaOH costs. In all but the most severe of the studied conditions, furfural formation was so limited that associated costs are considered negligible. Conclusions After the dilute maleic acid pretreatment and subsequent enzymatic hydrolysis, almost complete conversion of wheat straw glucan and xylan is possible. Taking maleic acid replenishment, heating, neutralization and furfural formation into account, the optimum in the dilute maleic acid pretreatment of

  4. Dilution

    PubMed Central

    Lavie, Nilli; Torralbo, Ana

    2010-01-01

    Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and Benoni (2010) find that distractor response competition effects can be reduced under conditions with a high search set size but low perceptual load (due to a singleton color target). They claim that the usual effect of search set size on distractor processing is not due to attentional load but instead attribute this to lower level visual interference. Here, we propose an account for their findings within load theory. We argue that in tasks of low perceptual load but high set size, an irrelevant distractor competes with the search nontargets for remaining capacity. Thus, distractor processing is reduced under conditions in which the search nontargets receive the spillover of capacity instead of the irrelevant distractor. We report a new experiment testing this prediction. Our new results demonstrate that, when peripheral distractor processing is reduced, it is the search nontargets nearest to the target that are perceived instead. Our findings provide new evidence for the spare capacity spillover hypothesis made by load theory and rule out accounts in terms of lower level visual interference (or mere “dilution”) for cases of reduced distractor processing under low load in displays of high set size. We also discuss additional evidence that discounts the viability of Tsal and Benoni's dilution account as an alternative to perceptual load. PMID:21133554

  5. 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.

  6. Bioconversion of dilute-acid pretreated sorghum bagasse to ethanol by Neurospora crassa.

    PubMed

    Dogaris, Ioannis; Gkounta, Olga; Mamma, Diomi; Kekos, Dimitris

    2012-07-01

    Bioethanol production from sweet sorghum bagasse (SB), the lignocellulosic solid residue obtained after extraction of sugars from sorghum stalks, can further improve the energy yield of the crop. The aim of the present work was to evaluate a cost-efficient bioconversion of SB to ethanol at high solids loadings (16 % at pretreatment and 8 % at fermentation), low cellulase activities (1-7 FPU/g SB) and co-fermentation of hexoses and pentoses. The fungus Neurospora crassa DSM 1129 was used, which exhibits both depolymerase and co-fermentative ability, as well as mixed cultures with Saccharomyces cerevisiae 2541. A dilute-acid pretreatment (sulfuric acid 2 g/100 g SB; 210 °C; 10 min) was implemented, with high hemicellulose decomposition and low inhibitor formation. The bioconversion efficiency of N. crassa was superior to S. cerevisiae, while their mixed cultures had negative effect on ethanol production. Supplementing the in situ produced N. crassa cellulolytic system (1.0 FPU/g SB) with commercial cellulase and β-glucosidase mixture at low activity (6.0 FPU/g SB) increased ethanol production to 27.6 g/l or 84.7 % of theoretical yield (based on SB cellulose and hemicellulose sugar content). The combined dilute-acid pretreatment and bioconversion led to maximum cellulose and hemicellulose hydrolysis 73.3 % and 89.6 %, respectively.

  7. Hydrolysis of Sulfur Dioxide in Small Clusters of Sulfuric Acid: Mechanistic and Kinetic Study.

    PubMed

    Liu, Jingjing; Fang, Sheng; Wang, Zhixiu; Yi, Wencai; Tao, Fu-Ming; Liu, Jing-Yao

    2015-11-17

    The deposition and hydrolysis reaction of SO2 + H2O in small clusters of sulfuric acid and water are studied by theoretical calculations of the molecular clusters SO2-(H2SO4)n-(H2O)m (m = 1,2; n = 1,2). Sulfuric acid exhibits a dramatic catalytic effect on the hydrolysis reaction of SO2 as it lowers the energy barrier by over 20 kcal/mol. The reaction with monohydrated sulfuric acid (SO2 + H2O + H2SO4 - H2O) has the lowest energy barrier of 3.83 kcal/mol, in which the cluster H2SO4-(H2O)2 forms initially at the entrance channel. The energy barriers for the three hydrolysis reactions are in the order SO2 + (H2SO4)-H2O > SO2 + (H2SO4)2-H2O > SO2 + H2SO4-H2O. Furthermore, sulfurous acid is more strongly bonded to the hydrated sulfuric acid (or dimer) clusters than the corresponding reactant (monohydrated SO2). Consequently, sulfuric acid promotes the hydrolysis of SO2 both kinetically and thermodynamically. Kinetics simulations have been performed to study the importance of these reactions in the reduction of atmospheric SO2. The results will give a new insight on how the pre-existing aerosols catalyze the hydrolysis of SO2, leading to the formation and growth of new particles.

  8. 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.

  9. 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.

  10. Integrated boiler, superheater, and decomposer for sulfuric acid decomposition

    DOEpatents

    Moore, Robert; Pickard, Paul S.; Parma, Jr., Edward J.; Vernon, Milton E.; Gelbard, Fred; Lenard, Roger X.

    2010-01-12

    A method and apparatus, constructed of ceramics and other corrosion resistant materials, for decomposing sulfuric acid into sulfur dioxide, oxygen and water using an integrated boiler, superheater, and decomposer unit comprising a bayonet-type, dual-tube, counter-flow heat exchanger with a catalytic insert and a central baffle to increase recuperation efficiency.

  11. Enhanced enzymatic hydrolysis of poplar bark by combined use of gamma ray and dilute acid for bioethanol production

    NASA Astrophysics Data System (ADS)

    Chung, Byung Yeoup; Lee, Jae Taek; Bai, Hyoung-Woo; Kim, Ung-Jin; Bae, Hyeun-Jong; Gon Wi, Seung; Cho, Jae-Young

    2012-08-01

    Pretreatment of poplar bark with a combination of sulfuric acid (3%, w/w, H2SO4) and gamma irradiation (0-1000 kGy) was performed in an attempt to enhance enzymatic hydrolysis for bioethanol production. The yields of reducing sugar were slightly increased with an increasing irradiation dose, ranging from 35.4% to 51.5%, with a 56.1% reducing sugar yield observed after dilute acid pretreatment. These results clearly showed that soluble sugars were released faster and to a greater extent in dilute acid-pretreated poplar bark than in gamma irradiation-pretreated bark. When combined pretreatment was carried out, a drastic increase in reducing sugar yield (83.1%) was found compared with individual pretreatment, indicating the possibility of increasing the convertibility of poplar bark following combined pretreatment. These findings are likely associated with cellulose crystallinity, lignin modification, and removal of hemicelluloses.

  12. 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 μg/kg and a limit of quantitation of 0.3 μg/kg. Recovery was close to 100% in the range of 3-300 μg/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 μg/kg (tomato ketchup, n = 9), 363 and 909 μg/kg (tomato paste, n = 2), and 8 and 247 μg/kg (pureed tomatoes and comparable products, n = 5).

  13. Sulfuric acid aerosols in the atmospheres of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    McGouldrick, Kevin; Toon, Owen B.; Grinspoon, David H.

    2011-08-01

    Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid/water solution that extends in altitude from roughly 50 km to roughly 80 km. Terrestrial polar stratospheric clouds (PSCs) form on stratospheric sulfuric acid aerosols, and both PSCs and stratospheric aerosols play a critical role in the formation of the ozone hole. Stratospheric aerosols can modify the climate when they are enhanced following volcanic eruptions, and are a current focus for geoengineering studies. Rain is made more acidic by sulfuric acid originating from sulfur dioxide generated by industry on Earth. Analysis of the sulfur content of Martian rocks has led to the hypothesis that an early Martian atmosphere, rich in SO 2 and H 2O, could support a sulfur-infused hydrological cycle. Here we consider the plausibility of frozen sulfuric acid in the upper clouds of Venus, which could lead to lightning generation, with implications for observations by the European Space Agency's Venus Express and the Japan Aerospace Exploration Agency's Venus Climate Orbiter (also known as Akatsuki). We also present simulations of a sulfur-rich early Martian atmosphere. We find that about 40 cm/yr of precipitation having a pH of about 2.0 could fall in an early Martian atmosphere, assuming a surface temperature of 273 K, and SO 2 generation rates consistent with the formation of Tharsis. This modeled acid rain is a powerful sink for SO 2, quickly removing it and preventing it from having a significant greenhouse effect.

  14. Improved enzymatic hydrolysis of wheat straw by combined use of gamma ray and dilute acid for bioethanol production

    NASA Astrophysics Data System (ADS)

    Hyun Hong, Sung; Taek Lee, Jae; Lee, Sungbeom; Gon Wi, Seung; Ju Cho, Eun; Singh, Sudhir; Sik Lee, Seung; Yeoup Chung, Byung

    2014-01-01

    Pretreating wheat straw with a combination of dilute acid and gamma irradiation was performed in an attempt to enhance the enzymatic hydrolysis for bioethanol production. The glucose yield was significantly affected by combined pretreatment (3% sulfuric acid-gamma irradiation), compared with untreated wheat straw and individual pretreatment. The increasing enzymatic hydrolysis after combined pretreatment is resulting from decrease in crystallinity of cellulose, loss of hemicelluloses, and removal or modification of lignin. Therefore, combined pretreatment is one of the most effective methods for enhancing the enzymatic hydrolysis of wheat straw biomass.

  15. Investigation of the thermal decomposition of sulfuric acid containing inorganic impurities

    SciTech Connect

    Kogtev, S.E.; Nikandrov, I.S.; Borisenko, A.S.; Peretrutov, A.A.

    1986-09-20

    Oleum is recovered by thermal decomposition of sulfuric acid wastes to sulfur dioxide with conversion of the sulfur dioxide to oleum. The organic substances in sulfuric acid wastes can affect the thermal-decomposition indexes of sulfuric acid wastes. They studied the effect of toluene, nitrotoluene, benzoic acid, and carbon on the yield of sulfur dioxide and also the possibility of reduction of acid vapors by products of pyrolysis and incomplete combustion of hydrocarbons. It is shown that the yield of sulfur dioxide in thermal decomposition of hydrocarbon-containing sulfuric acid wastes can be increased if the process assumes the nature of reductive decomposition.

  16. Stagewise dilute-acid pretreatment and enzyme hydrolysis of distillers' grains and corn fiber.

    PubMed

    Noureddini, Hossein; Byun, Jongwon; Yu, Ta-Jen

    2009-11-01

    Distillers' grains and corn fiber are the coproducts of the corn dry grind and wet milling industries, respectively. Availability of distillers' grains and corn fiber at the ethanol plant and their high levels of lignocellulosic material make these coproducts attractive feedstocks for conversion to ethanol. In this study, dilute sulfuric acid hydrolysis of these coproducts was investigated in a multistage scheme. After the completion of each pretreatment stage, the liquid substrate was separated and reused in the succeeding pretreatment stage with a fresh substrate. The substrate from each stage was also subjected to enzyme hydrolysis in a separate experiment. The sulfuric acid concentration and the substrate loading were maintained at 1.0 vol% and 15.0 wt.%, respectively, and the temperature was maintained at 120 degrees C in all the experiments. Experiments were also performed to study the effect of removing oil from the samples prior to the pretreatment. The highest concentration of monomeric sugars (MS) was observed when three stages of pretreatment were followed by the enzyme reaction. The enzyme hydrolysis of the three-stage pretreated dried distillers' grains and corn fiber yielded 122.6 +/- 5.8 and 184.5 +/- 4.1 mg/mL of MS, respectively. The formation of inhibitory products was also monitored.

  17. Detoxification of dilute acid hydrolysates of lignocellulose with lime.

    PubMed

    Martinez, A; Rodriguez, M E; Wells, M L; York, S W; Preston, J F; Ingram, L O

    2001-01-01

    The hydrolysis of hemicellulose to monomeric sugars by dilute acid hydrolysis is accompanied by the production of inhibitors that retard microbial fermentation. Treatment of hot hydrolysate with Ca(OH)(2) (overliming) is an effective method for detoxification. Using ethanologenic Escherichia coli LY01 as the biocatalyst, our results indicate that the optimal lime addition for detoxification varies and depends on the concentration of mineral acids and organic acids in each hydrolysate. This optimum was shown to be readily predicted on the basis of the titration of hydrolysate with 2 N NaOH at ambient temperature to either pH 7.0 or pH 11.0. The average composition of 15 hydrolysates prior to treatment was as follows (per L): 95.24 +/- 7.29 g sugar, 5.3 +/- 2.99 g acetic acid, 1.305 +/- 0.288 g total furans (furfural and hydroxymethylfurfural), and 2.86 +/- 0.34 g phenolic compounds. Optimal overliming resulted in a 51 +/- 9% reduction of total furans, a 41 +/- 6% reduction in phenolic compounds, and a 8.7 +/- 4.5% decline in sugar. Acetic acid levels were unchanged. Considering the similarity of microorganisms, it is possible that the titration method described here may also prove useful for detoxification and fermentation processes using other microbial biocatalysts.

  18. Protein and sulfur amino acid requirements of broiler breeder hens.

    PubMed

    Harms, R H; Wilson, H R

    1980-02-01

    Two experiments were conducted with Cobb color-sexed broiler breeder hens to determine their protein and sulfur amino acid requirement. A daily intake between 400 and 478 mg of methionine and between 722 and 839 mg of total sulfur amino acids was necessary for maximum egg production, the latter in a diet of 13.07% protein. Slightly lower levels supported maximum body weights. Hens laying at the highest rate consumed 23.4 g of protein per day.

  19. Pressure leaching of metals from waste printed circuit boards using sulfuric acid

    NASA Astrophysics Data System (ADS)

    Jha, Manis K.; Lee, Jae-Chun; Kumari, Archana; Choubey, Pankaj K.; Kumar, Vinay; Jeong, Jinki

    2011-08-01

    Printed circuit boards (PCBs) are essential components of electronic equipments which contain various metallic values. This paper reports a hydrometallurgical recycling process for waste PCBs, which consists of the novel pretreatment consisting of organic swelling of PCBs followed by sulfuric acid leaching of metals from waste PCBs. To recycle the waste PCBs, experiments were carried out for the recovery of copper from the crushed and organic swelled materials of waste PCBs using sulfuric acid leaching in presence of hydrogen peroxide under atmospheric and pressure condition. The leaching of PCBs at 90°C, pulp density 100 g/L under atmospheric condition, using 6M sulfuric acid resulted in the dissolution of a minor amount of copper due to the presence of plastic coating on the surface of metallic layers. On the other hand, when the liberated metal sheets from organic swelled PCBs were treated with dilute sulfuric acid of concentration 2M along with hydrogen peroxide in an autoclave under oxygen atmosphere, the percentage recovery of copper was found to increase from 59.63% to 97.01% with an increase in hydrogen peroxide concentration from 5 to 15% (v/v) keeping constant pulp density 30 g/L.

  20. 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.

  1. Kinetics of glucose decomposition during dilute-acid hydrolysis of lignocellulosic biomass.

    PubMed

    Xiang, Qian; Lee, Yong Y; Torget, Robert W

    2004-01-01

    Recent research work in-house both at Auburn University and National Renewable Energy Laboratory has demonstrated that extremely low concentrations of acid (e.g., 0.05-0.2 wt% sulfuric acid) and high temperatures (e.g., 200-230 degrees C) are reaction conditions that can be effectively applied for hydrolysis of the cellulosic component of biomass. These conditions are far from those of the conventional dilute-acid hydrolysis processes, and the kinetic data for glucose decomposition are not currently available. We investigated the kinetics of glucose decomposition covering pH values of 1.5-2.2 and temperatures of 180-230 degrees C using glass ampoule reactors. The primary factors controlling glucose decomposition are the reaction medium, acid concentration, and temperature. Based on the experimental data, a kinetic model was developed and the best-fit kinetic parameters were determined. However, a consistent discrepancy in the rate of glucose disappearance was found between that of the model based on pure glucose data and that observed during the actual process of lignocellulosic biomass hydrolysis. This was taken as an indication that glucose recombines with acid-soluble lignin during the hydrolysis process, and this conclusion was incorporated accordingly into the overall model of glucose decomposition.

  2. Tested Demonstrations: Color Oscillations in the Formic Acid-Nitric Acid-Sulfuric Acid System.

    ERIC Educational Resources Information Center

    Raw, C. J. G.; And Others

    1983-01-01

    Presented are procedures for demonstrating the production of color oscillations when nitric acid is added to a formic acid/concentrated sulfuric acid mixture. Because of safety considerations, "Super-8" home movie of the color changes was found to be satisfactory for demonstration purposes. (JN)

  3. Dilute acid pretreatment of rapeseed straw for fermentable sugar generation.

    PubMed

    Castro, Eulogio; Díaz, Manuel J; Cara, Cristóbal; Ruiz, Encarnación; Romero, Inmaculada; Moya, Manuel

    2011-01-01

    The influence of the main pretreatment variables on fermentable sugar generation from rapeseed straw is studied using an experimental design approach. Low and high levels for pretreatment temperature (140-200 °C), process time (0-20 min) and concentration of sulfuric acid (0.5-2% w/v) were selected according to previous results. Glucose and xylose composition, as well as sugar degradation, were monitored and adjusted to a quadratic model. Non-sugar components of the hydrolysates were also determined. Enzymatic hydrolysis yields were used for assessing pretreatment performance. Optimization based on the mathematical model show that total conversion of cellulose from pretreated solids can be achieved at pretreatment conditions of 200 °C for 27 min and 0.40% free acid concentration. If optimization criteria were based on maximization of hemicellulosic sugars recovery in the hydrolysate along with cellulose preservation in the pretreated solids, milder pretreatment conditions of 144 °C, 6 min and 2% free acid concentration should be used.

  4. Effect of temperature on iron leaching from bauxite residue by sulfuric acid.

    PubMed

    Liu, Zhi-Rong; Zeng, Kai; Zhao, Wei; Li, Ying

    2009-01-01

    Bauxite residue, as solid waste from alumina production, contains mainly hematite [Fe2O3]. Kinetic study of iron leaching of bauxite residue by diluted sulfuric acid at atmospheric pressure has been investigated. The results have been obtained as following: (i) Temperature play an important role in iron leaching from bauxite residue. Higher temperature is favor of Fe(III) leaching from bauxite residue. (ii) The leaching process is applicable to the intra-particle diffusion model and the apparent activation energy of model of leaching is found to be 17.32 kJ/mol.

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

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    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. Connection of sulfuric acid to atmospheric nucleation in boreal forest.

    PubMed

    Nieminen, T; Manninen, H E; Sihto, S L; Yli-Juuti, T; Mauldin, R L; Petäjä, T; Riipinen, I; Kerminen, V M; Kulmala, M

    2009-07-01

    Gas to particle conversion in the boundary layer occurs worldwide. Sulfuric acid is considered to be one of the key components in these new particle formation events. In this study we explore the connection between measured sulfuric acid and observed formation rate of both charged 2 nm as well as neutral clusters in a boreal forest environment A very short time delay of the order of ten minutes between these two parameters was detected. On average the event days were clearly associated with higher sulfuric acid concentrations and lower condensation sink (CS) values than the nonevent days. Although there was not a clear sharp boundary between the nucleation and no-nucleation days in sulfuric acid-CS plane, at our measurement site a typical threshold concentration of 3.10(5) molecules cm(-3) of sulfuric acid was needed to initiate the new particle formation. Two proposed nucleation mechanisms were tested. Our results are somewhat more in favor of activation type nucleation than of kinetic type nucleation, even though our data set is too limited to omit either of these two mechanisms. In line with earlier studies, the atmospheric nucleation seems to start from sizes very close to 2 nm.

  7. Molecular interaction of pinic acid with sulfuric acid: exploring the thermodynamic landscape of cluster growth.

    PubMed

    Elm, Jonas; Kurtén, Theo; Bilde, Merete; Mikkelsen, Kurt V

    2014-09-11

    We investigate the molecular interactions between the semivolatile α-pinene oxidation product pinic acid and sulfuric acid using computational methods. The stepwise Gibbs free energies of formation have been calculated utilizing the M06-2X functional, and the stability of the clusters is evaluated from the corresponding ΔG values. The first two additions of sulfuric acid to pinic acid are found to be favorable with ΔG values of -9.06 and -10.41 kcal/mol. Addition of a third sulfuric acid molecule is less favorable and leads to a structural rearrangement forming a bridged sulfuric acid-pinic acid cluster. The involvement of more than one pinic acid molecule in a single cluster is observed to lead to the formation of favorable (pinic acid)2(H2SO4) and (pinic acid)2(H2SO4)2 clusters. The identified most favorable growth paths starting from a single pinic acid molecule lead to closed structures without the further possibility for attachment of either sulfuric acid or pinic acid. This suggests that pinic acid cannot be a key species in the first steps in nucleation, but the favorable interactions between sulfuric acid and pinic acid imply that pinic acid can contribute to the subsequent growth of an existing nucleus by condensation.

  8. 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

  9. A whole cell biocatalyst for cellulosic ethanol production from dilute acid-pretreated corn stover hydrolyzates.

    PubMed

    Ryu, Seunghyun; Karim, Muhammad Nazmul

    2011-08-01

    In this research, a recombinant whole cell biocatalyst was developed by expressing three cellulases from Clostridium cellulolyticum--endoglucanase (Cel5A), exoglucanase (Cel9E), and β-glucosidase--on the surface of the Escherichia coli LY01. The modified strain is identified as LY01/pRE1H-AEB. The cellulases were displayed on the surface of the cell by fusing with an anchor protein, PgsA. The developed whole cell biocatalyst was used for single-step ethanol fermentation using the phosphoric acid-swollen cellulose (PASC) and the dilute acid-pretreated corn stover. Ethanol production was 3.59 ± 0.15 g/L using 10 g/L of PASC, which corresponds to a theoretical yield of 95.4 ± 0.15%. Ethanol production was 0.30 ± 0.02 g/L when 1 g/L equivalent of glucose in the cellulosic fraction of the dilute sulfuric acid-pretreated corn stover (PCS) was fermented for 84 h. A total of 0.71 ± 0.12 g/L ethanol was produced in 48 h when the PCS was fermented in the simultaneous saccharification and co-fermentation mode using the hemicellulosic (1 g/L of total soluble sugar) and as well as the cellulosic (1 g/L of glucose equivalent) parts of PCS. In a control experiment, 0.48 g/L ethanol was obtained from 1 g/L of hemicellulosic PCS. It was concluded that the whole cell biocatalyst could convert both cellulosic and hemicellulosic substrates into ethanol in a single reactor. The developed C. cellulolyticum-E. coli whole cell biocatalyst also overcame the incompatible temperature problem of the frequently reported fungal-yeast systems.

  10. Characterization of lignin derived from water-only and dilute acid flowthrough pretreatment of poplar wood at elevated temperatures

    DOE PAGES

    Zhang, Libing; Yan, Lishi; Wang, Zheming; ...

    2015-12-01

    In this study, flowthrough pretreatment of biomass has high potential to valorize lignin derivatives to high-value products, which is vital to enhance the economy of biorefinery plants. Comprehensive understanding of lignin behaviors and solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of providing flexible platform for lignin utilization. In this study, the effects of flowthrough pretreatment conditions on lignin separation from poplar wood were reported as well as the characteristics of three sub-sets of lignin produced from the pretreatment, including residual lignin in pretreated solid residues (ReL),more » recovered insoluble lignin in pretreated liquid (RISL), and recovered soluble lignin in pretreatment liquid (RSL). Both the water-only and 0.05% (w/w) sulfuric acid pretreatments were performed at temperatures from 160 to 270°C on poplar wood in a flowthrough reactor system for 2-10 min. Results showed that water-only flowthrough pretreatment primarily removed syringyl (S units). Increased temperature and/or the addition of sulfuric acid enhanced the removal of guaiacyl (G units) compared to water-only pretreatments at lower temperatures, resulting in nearly complete removal of lignin from the biomass. Results also suggested that more RISL was recovered than ReL and RSL in both dilute acid and water-only flowthrough pretreatment at elevated temperatures. NMR spectra of the RISL revealed significant β-O-4 cleavage, α-β deoxygenation to form cinnamyl-like end groups, and slight β-5 repolymerization in both water-only and dilute acid flowthrough pretreatments. In conclusion, elevated temperature and/or dilute acid greatly enhanced lignin removal to almost 100% by improving G unit removal besides S unit removal in flowthrough system. A new lignin chemistry transformation pathway was proposed and revealed the complexity of lignin structural change

  11. High pressure sulfuric acid decomposition experiments for the sulfur-iodine thermochemical cycle.

    SciTech Connect

    Velasquez, Carlos E; Reay, Andrew R.; Andazola, James C.; Naranjo, Gerald E.; Gelbard, Fred

    2005-09-01

    A series of three pressurized sulfuric acid decomposition tests were performed to (1) obtain data on the fraction of sulfuric acid catalytically converted to sulfur dioxide, oxygen, and water as a function of temperature and pressure, (2) demonstrate real-time measurements of acid conversion for use as process control, (3) obtain multiple measurements of conversion as a function of temperature within a single experiment, and (4) assess rapid quenching to minimize corrosion of metallic components by undecomposed acid. All four of these objectives were successfully accomplished. This report documents the completion of the NHI milestone on high pressure H{sub 2}SO{sub 4} decomposition tests for the Sulfur-Iodine (SI) thermochemical cycle project. All heated sections of the apparatus, (i.e. the boiler, decomposer, and condenser) were fabricated from Hastelloy C276. A ceramic acid injection tube and a ceramic-sheathed thermocouple were used to minimize corrosion of hot liquid acid on the boiler surfaces. Negligible fracturing of the platinum on zirconia catalyst was observed in the high temperature decomposer. Temperature measurements at the exit of the decomposer and at the entry of the condenser indicated that the hot acid vapors were rapidly quenched from about 400 C to less than 20 C within a 14 cm length of the flow path. Real-time gas flow rate measurements of the decomposition products provided a direct measurement of acid conversion. Pressure in the apparatus was preset by a pressure-relief valve that worked well at controlling the system pressure. However, these valves sometimes underwent abrupt transitions that resulted in rapidly varying gas flow rates with concomitant variations in the acid conversion fraction.

  12. 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

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

  13. 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

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

  14. 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

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

  15. 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

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

  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

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

  17. Adsorption of ammonia by sulfuric acid treated zirconium hydroxide.

    PubMed

    Glover, T Grant; Peterson, Gregory W; DeCoste, Jared B; Browe, Matthew A

    2012-07-17

    The adsorption of ammonia on Zr(OH)(4), as well as Zr(OH)(4) treated with sulfuric acid, were examined. The results show that treating Zr(OH)(4) with sulfuric acid leads to the formation of a sulfate on the surface of the material, and that the sulfate contributes to the ammonia adsorption capacity through the formation of an ammonium sulfates species. Calcination of Zr(OH)(4) decreases the ammonia adsorption capacity of the material and limits the formation of sulfate species. NMR and FTIR spectroscopy results are presented that show the presence of two distinct ammonium species on the surface of the material. The adsorption capacity of the materials is shown to be a complex phenomenon that is impacted by the surface area, the sulfur content, and the pH of the material. The results illustrate that Zr(OH)(4), which is known to adsorb acidic gases, can be modified and used to adsorb basic gases.

  18. Air pollution and asthma: clinical studies with sulfuric acid aerosols

    SciTech Connect

    Utell, M.J.; Frampton, M.W.; Morrow, P.E. )

    1991-11-01

    Until recently, acid deposition has been widely considered a serious ecological problem but not a threat to human health. The controlled clinical study is an important approach in linking acidic aerosol inhalation with respiratory effects. Asthmatic patients represent a subpopulation most responsive to sulfuric acid aerosols. In a series of studies with asthmatic volunteers, several factors have been identified that may modulate the intensity of the bronchoconstrictor response to inhaled acidic aerosols. We found (1) enhancement of the bronchoconstrictor response during exercise, (2) the more acidic aerosols provoke the greatest changes in lung function, and (3) mitigation of airway responses during sulfuric acid aerosol inhalation caused by high respiratory ammonia concentrations. Additional factors influencing responsiveness await identification.

  19. Protonation Dynamics and Hydrogen Bonding in Aqueous Sulfuric Acid.

    PubMed

    Niskanen, Johannes; Sahle, Christoph J; Juurinen, Iina; Koskelo, Jaakko; Lehtola, Susi; Verbeni, Roberto; Müller, Harald; Hakala, Mikko; Huotari, Simo

    2015-09-03

    Hydration of sulfuric acid plays a key role in new-particle formation in the atmosphere. It has been recently proposed that proton dynamics is crucial in the stabilization of these clusters. One key question is how water molecules mediate proton transfer from sulfuric acid, and hence how the deprotonation state of the acid molecule behaves as a function concentration. We address the proton transfer in aqueous sulfuric acid with O K edge and S L edge core-excitation spectra recorded using inelastic X-ray scattering and with ab initio molecular dynamics simulations in the concentration range of 0-18.0 M. Throughout this range, we quantify the acid-water interaction with atomic resolution. Our simulations show that the number of donated hydrogen bonds per Owater increases from 1.9 to 2.5 when concentration increases from 0 to 18.0 M, in agreement with a rapid disappearance of the pre-edge feature in the O K edge spectrum. The simulations also suggest that for 1.5 M sulfuric acid SO4(2-) is most abundant and that its concentration falls monotonously with increasing concentration. Moreover, the fraction of HSO4(-) peaks at ∼12 M.

  20. Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments

    SciTech Connect

    Zhang, Yan; Inouye, Hideyo; Yang, Lin; Himmel, Michael E.; Tucker, Melvin; Makowski, Lee

    2015-02-28

    Cellulose can work as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose at two distinct length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. Our results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.

  1. Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments

    SciTech Connect

    Zhang, Yan; Inouye, Hideyo; Yang, Lin; Himmel, Michael E.; Tucker, Melvin; Makowski, Lee

    2015-02-28

    Cellulose is an attractive candidate as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose at two distinct length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. Lastly, these results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.

  2. Breakdown of hierarchical architecture in cellulose during dilute acid pretreatments

    DOE PAGES

    Zhang, Yan; Inouye, Hideyo; Yang, Lin; ...

    2015-02-28

    Cellulose is an attractive candidate as a feedstock for sustainable bioenergy because of its global abundance. Pretreatment of biomass has significant influence on the chemical availability of cellulose locked in recalcitrant microfibrils. Optimizing pretreatment depends on an understanding of its impact on the microscale and nanoscale molecular architecture. X-ray scattering experiments have been performed on native and pre-treated maize stover and models of cellulose architecture have been derived from these data. Ultra small-angle, very small-angle and small-angle X-ray scattering (USAXS, VSAXS and SAXS) probe three different levels of architectural scale. USAXS and SAXS have been used to study cellulose atmore » two distinct length scales, modeling the fibrils as ~30 Å diameter rods packed into ~0.14 μm diameter bundles. VSAXS is sensitive to structural features at length scales between these two extremes. Detailed analysis of diffraction patterns from untreated and pretreated maize using cylindrical Guinier plots and the derivatives of these plots reveals the presence of substructures within the ~0.14 μm diameter bundles that correspond to grouping of cellulose approximately 30 nm in diameter. These sub-structures are resilient to dilute acid pretreatments but are sensitive to pretreatment when iron sulfate is added. Lastly, these results provide evidence of the hierarchical arrangement of cellulose at three length scales and the evolution of these arrangements during pre-treatments.« less

  3. Sulfuric acid measurements in the exhaust plume of a jet aircraft in flight: Implications for the sulfuric acid formation efficiency

    NASA Astrophysics Data System (ADS)

    Curtius, J.; Arnold, F.; Schulte, P.

    2002-04-01

    Sulfuric acid concentrations were measured in the exhaust plume of a B737-300 aircraft in flight. The measurements were made onboard of the German research aircraft Falcon using the Volatile Aerosol Component Analyzer (VACA). The VACA measures total H2SO4, which is the sum of gaseous H2SO4 and aerosol H2SO4. Measurements took place at distances of 25-200 m behind the B737 corresponding to plume ages of about 0.1-1 seconds. The fuel sulfur content (FSC) of the fuel burned by the B737 engines was alternatively 2.6 and 56 mg sulfur per kilogram fuel (ppmm). H2SO4 concentrations measured in the plume for the 56 ppmm sulfur case were up to ~600 pptv. The average concentration of H2SO4 measured in the ambient atmosphere outside the aircraft plume was 88 pptv, the maximum ambient atmospheric H2SO4 was ~300 pptv. Average efficiencies ɛΔCO2 = 3.3 +/- 1.8% and ɛΔT = 2.9 +/- 1.6% for fuel sulfur conversion to sulfuric acid were inferred when relating the H2SO4 data to measurements of the plume tracers ΔCO2 and ΔT.

  4. Enhanced enzymatic hydrolysis of kenaf core using irradiation and dilute acid

    NASA Astrophysics Data System (ADS)

    Lee, Byoung-Min; Jeun, Joon-Pyo; Kang, Phil-Hyun

    2017-01-01

    This study was performed to determine the effect of electron beam dose and enzymatic hydrolysis time for production of sugar such as glucose and xylose. After kenaf core was exposed to an irradiation dose that ranged from 0 to 500 kGy, the irradiated kenaf core was treated with a 3% (v/v) sulfuric acid solution using an autoclave for 5 h at 120 °C. The pretreated kenaf core was subsequently subjected to enzymatic hydrolysis at 50 °C in a shaking water bath at 150 rpm for 12, 24, 48, and 72 h. The determined enzyme activity rates were 70 FPU (Celluclast 1.5 L) and 40 CBU (Novozyme-188). The crystallinity index decreased from 50.6% in a non-pretreated kenaf core to 27.7% in kenaf core that was subjected to the two-stage pretreatment at dose of 500 kGy. The sugar yield of the two-stage pretreated kenaf core increased with an increase in irradiation dose. The sugar yield after 72 h of enzymatic hydrolysis was 73.6% at its highest with an irradiation dose of 500 kGy. The enhancement of enzymatic hydrolysis by two-stage pretreatment was more effective than non- and single pretreatment (36.9%, 40.6% and 44.0% in non-pretreatment, electron beam and dilute acid, respectively).

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

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirements for sulfuric acid and oleum. 153... and Equipment Special Requirements § 153.556 Special requirements for sulfuric acid and oleum. (a... acid, oleum, or contaminated sulfuric acid are approved by the Commandant (CG-522) on a case by...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Special requirements for sulfuric acid and oleum. 153... and Equipment Special Requirements § 153.556 Special requirements for sulfuric acid and oleum. (a... acid, oleum, or contaminated sulfuric acid are approved by the Commandant (CG-ENG) on a case by...

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Special requirements for sulfuric acid and oleum. 153... and Equipment Special Requirements § 153.556 Special requirements for sulfuric acid and oleum. (a... acid, oleum, or contaminated sulfuric acid are approved by the Commandant (CG-ENG) on a case by...

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

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Special requirements for sulfuric acid and oleum. 153... and Equipment Special Requirements § 153.556 Special requirements for sulfuric acid and oleum. (a... acid, oleum, or contaminated sulfuric acid are approved by the Commandant (CG-522) on a case by...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Special requirements for sulfuric acid and oleum. 153... and Equipment Special Requirements § 153.556 Special requirements for sulfuric acid and oleum. (a... acid, oleum, or contaminated sulfuric acid are approved by the Commandant (CG-ENG) on a case by...

  10. Selection of suitable mineral acid and its concentration for biphasic dilute acid hydrolysis of the sodium dithionite delignified Prosopis juliflora to hydrolyze maximum holocellulose.

    PubMed

    Naseeruddin, Shaik; Desai, Suseelendra; Venkateswar Rao, L

    2016-02-01

    Two grams of delignified substrate at 10% (w/v) level was subjected to biphasic dilute acid hydrolysis using phosphoric acid, hydrochloric acid and sulfuric acid separately at 110 °C for 10 min in phase-I and 121 °C for 15 min in phase-II. Combinations of acid concentrations in two phases were varied for maximum holocellulose hydrolysis with release of fewer inhibitors, to select the suitable acid and its concentration. Among three acids, sulfuric acid in combination of 1 & 2% (v/v) hydrolyzed maximum holocellulose of 25.44±0.44% releasing 0.51±0.02 g/L of phenolics and 0.12±0.002 g/L of furans, respectively. Further, hydrolysis of delignified substrate using selected acid by varying reaction time and temperature hydrolyzed 55.58±1.78% of holocellulose releasing 2.11±0.07 g/L and 1.37±0.03 g/L of phenolics and furans, respectively at conditions of 110 °C for 45 min in phase-I & 121 °C for 60 min in phase-II.

  11. Microbial Sulfur Cycling in an Acid Mine Lake

    NASA Astrophysics Data System (ADS)

    Bernier, L.; Warren, L. A.

    2004-12-01

    Geochemical dynamics of a tailings impacted lake in Northern Ontario were investigated over a three-year period, in which active pyrrhotite slurry disposal was initiated in year two. A strong seasonal trend of decreasing epilimnetic pH with significant diurnal acid production, pre-, during and post slurry deposition was observed with high rates observed compared to pre-slurry. Slurry deposition occurred at the surface of the lake and acted as a reaction stimulant for acid generation. Over the diurnal timescale investigated, the highest rates of acid production occurred not at the lake surface but within the metaliminetic region of the lake. This region was exemplified by strong decreasing oxygen gradients, and thus observed high rates of acid generation are more consistent with microbial pathways of sulfur oxidation than with abiotic, oxygen catalyzed pathways. Consistent with microbial catalysis, metalimnetic rates of acid generation were highest during June and July when microbial populations and metabolic rates were maximal. These results indicate that microbial oxidation of sulfur species play a major role in acid generation in this system. Further, observed rates of acid generation exceed those predicted by published abiotic rates of pyrrhotite oxidation, but are consistent with literature estimates of acid generation catalyzed by microbial activity. Acidithiobacilli accounted for up to 50% of the microbial community pre slurry, but were absent post slurry deposition. These results are the first to demonstrate quantitatively that microbial sulfur oxidation can play a predominant role in acid generation within mine tailings impacted systems. They further highlight the need to evaluate the more complex pathways by which microorganisms process sulfur as the conditions, controls and process rates differ from those observed for abiotic reactions.

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

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1981-01-01

    A series of liquids have been screened as candidate heat exchange fluids for service in thermochemical cycles that involve the vaporization of sulfuric acid. The required chemical and physical criteria of the liquids is described with the results of some preliminary high temperature test data presented.

  13. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  14. 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...

  15. Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

  16. Heat-Exchange Fluids for Sulfuric Acid Vaporizers

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Petersen, G. R.

    1982-01-01

    Some fluorine-substituted organic materials meet criteria for heat-exchange fluids in contact with sulfuric acid. Most promising of these are perfluoropropylene oxide polymers with degree of polymerization (DP) between 10 and 50. It is desirable to have DP in high range because vapor pressure of material decreases as DP increases, and high-DP liquids have lower loss due to vaporization.

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

    PubMed

    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.

  18. The averaging effect of odorant mixing as determined by air dilution sensory tests: a case study on reduced sulfur compounds.

    PubMed

    Kim, Ki-Hyun

    2011-01-01

    To learn more about the effects of mixing different odorants, a series of air dilution sensory (ADS) tests were conducted using four reduced sulfur compounds [RSC: hydrogen sulfide (H(2)S), methanethiol (CH(3)SH), dimethylsulfide (DMS), and dimethyldisulfide (DMDS)] at varying concentration levels. The tests were initially conducted by analyzing samples containing single individual RSCs at a wide range of concentrations. The resulting data were then evaluated to define the empirical relationship for each RSC between the dilution-to-threshold (D/T) ratio and odor intensity (OI) scaling. Based on the relationships defined for each individual RSC, the D/T ratios were estimated for a synthetic mixture of four RSCs. The effect of mixing was then examined by assessing the relative contribution of each RSC to those estimates with the aid of the actually measured D/T values. This stepwise test confirmed that the odor intensity of the synthetic mixture is not governed by the common theoretical basis (e.g., rule of additivity, synergism, or a stronger component model) but is best represented by the averaged contribution of all RSC components. The overall results of this study thus suggest that the mixing phenomenon between odorants with similar chemical properties (like RSC family) can be characterized by the averaging effect of all participants.

  19. Dissolution, speciation, and reaction of acetaldehyde in cold sulfuric acid

    NASA Astrophysics Data System (ADS)

    Michelsen, Rebecca R.; Ashbourn, Samantha F. M.; Iraci, Laura T.

    2004-12-01

    The uptake of gas-phase acetaldehyde [CH3CHO, ethanal] by aqueous sulfuric acid solutions was studied under upper tropospheric/lower stratospheric (UT/LS) conditions. The solubility of acetaldehyde was found to be low, between 2 × 102 M atm-1 and 1.5 × 105 M atm-1 under the ranges of temperature (211-241 K) and acid composition (39-76 weight percent, wt%, H2SO4) studied. Under most conditions, acetaldehyde showed simple solubility behavior when exposed to sulfuric acid. Under moderately acidic conditions (usually 47 wt% H2SO4), evidence of reaction was observed. Enhancement of uptake at long times was occasionally detected in conjunction with reaction. The source of these behaviors and the effect of acetaldehyde speciation on solubility are discussed. Implications for the uptake of oxygenated organic compounds by tropospheric aerosols are considered.

  20. Recovery of high purity sulfuric acid from the waste acid in toluene nitration process by rectification.

    PubMed

    Song, Kai; Meng, Qingqiang; Shu, Fan; Ye, Zhengfang

    2013-01-01

    Waste sulfuric acid is a byproduct generated from numerous industrial chemical processes. It is essential to remove the impurities and recover the sulfuric acid from the waste acid. In this study the rectification method was introduced to recover high purity sulfuric acid from the waste acid generated in toluene nitration process by using rectification column. The waste acid quality before and after rectification were evaluated using UV-Vis spectroscopy, GC/MS, HPLC and other physical and chemical analysis. It was shown that five nitro aromatic compounds in the waste acid were substantially removed and high purity sulfuric acid was also recovered in the rectification process at the same time. The COD was removed by 94% and the chrominance was reduced from 1000° to 1°. The recovered sulfuric acid with the concentration reaching 98.2 wt% had a comparable quality with commercial sulfuric acid and could be recycled back into the toluene nitration process, which could avoid waste of resources and reduce the environmental impact and pollution.

  1. Color Change of Sudan III against Concentrated Sulfuric Acid in Acetonitrile and Quantification for a Small Amount of Concentrated Sulfuric Acid.

    PubMed

    Sakurai, Takao; Kurata, Shoji; Ogino, Kenji

    2016-01-01

    The color-changing phenomenon of hydrophobic bisazo dye, Sudan III in an acetonitrile solution against the addition of concentrated sulfuric acid has been discovered and the chromic properties investigated. Based on observations, a novel quantification method of concentrated sulfuric acid has been developed. Sudan III changes its color from orange to blue against a small volume of sulfuric acid, and the acetonitrile solution of Sudan III is the most suitable for observing the color-change phenomenon. (1)H-NMR and UV-Vis spectroscopic studies showed that the color-change mechanism of Sudan III against sulfuric acid is due to the protonation of the dye by sulfuric acid. This phenomenon is applicable to the quantification of concentrated sulfuric acid by introducing the Hammett acidity function. The proposed method requires only a small amount of the sample, 0.04 mL, and enables rapid quantification.

  2. Nuclei-mode particulate emissions and their response to fuel sulfur content and primary dilution during transient operations of old and modern diesel engines.

    PubMed

    Liu, Z Gerald; Vasys, Victoria N; Kittelson, David B

    2007-09-15

    The effects of fuel sulfur content and primary dilution on PM number emissions were investigated during transient operations of an old and a modern diesel engine. Emissions were also studied during steady-state operations in order to confirm consistency with previous findings. Testing methods were concurrent with those implemented by the EPA to regulate PM mass emissions, including the use of the Federal Transient Testing Procedure-Heavy Duty cycle to simulate transient conditions and the use of a Critical Flow Venturi-Constant Volume System to provide primary dilution. Steady-state results were found to be consistent with previous studies in that nuclei-mode particulate emissions were largely reduced when lower-sulfur content fuel was used in the newer engine, while the nuclei-mode PM emissions from the older engine were much less affected by fuel sulfur content. The transient results, however, show that the total number of nuclei-mode PM emissions from both engines increases with fuel sulfur content, although this effect is only seen under the higher primary dilution ratios with the older engine. Transient results further show that higher primary dilution ratios increase total nuclei-mode PM number emissions in both engines.

  3. 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.

  4. 40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Sulfuric acid; exemption from the... Exemptions From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement of a tolerance when used in accordance...

  5. 40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Sulfuric acid; exemption from the... Exemptions From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement of a tolerance when used in accordance...

  6. 40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Sulfuric acid; exemption from the... Exemptions From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement of a tolerance when used in accordance...

  7. 40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Sulfuric acid; exemption from the... Exemptions From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement of a tolerance when used in accordance...

  8. 40 CFR 180.1019 - Sulfuric acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Sulfuric acid; exemption from the... Exemptions From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement of a tolerance when used in accordance...

  9. 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

  10. 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.

  11. Effect of lignin content on changes occurring in poplar cellulose ultrastructure during dilute acid pretreatment

    SciTech Connect

    Sun, Qining; Foston, Marcus; Meng, Xianzhi; Sawada, Daisuke; Pingali, Sai Venkatesh; O’Neill, Hugh M.; Li, Hongjia; Wyman, Charles E.; Langan, Paul; Ragauskas, Art J.; Kumar, Rajeev

    2014-10-14

    Obtaining a better understanding of the complex mechanisms occurring during lignocellulosic deconstruction is critical to the continued growth of renewable biofuel production. A key step in bioethanol production is thermochemical pretreatment to reduce plant cell wall recalcitrance for downstream processes. Previous studies of dilute acid pretreatment (DAP) have shown significant changes in cellulose ultrastructure that occur during pretreatment, but there is still a substantial knowledge gap with respect to the influence of lignin on these cellulose ultrastructural changes. This study was designed to assess how the presence of lignin influences DAP-induced changes in cellulose ultrastructure, which might ultimately have large implications with respect to enzymatic deconstruction efforts. Native, untreated hybrid poplar (Populus trichocarpa x Populus deltoids) samples and a partially delignified poplar sample (facilitated by acidic sodium chlorite pulping) were separately pretreated with dilute sulfuric acid (0.10 M) at 160°C for 15 minutes and 35 minutes, respectively . Following extensive characterization, the partially delignified biomass displayed more significant changes in cellulose ultrastructure following DAP than the native untreated biomass. With respect to the native untreated poplar, delignified poplar after DAP (in which approximately 40% lignin removal occurred) experienced: increased cellulose accessibility indicated by increased Simons’ stain (orange dye) adsorption from 21.8 to 72.5 mg/g, decreased cellulose weight-average degree of polymerization (DPw) from 3087 to 294 units, and increased cellulose crystallite size from 2.9 to 4.2 nm. These changes following DAP ultimately increased enzymatic sugar yield from 10 to 80%. We conclude that, overall, the results indicate a strong influence of lignin content on cellulose ultrastructural changes occurring during DAP. With the reduction of lignin content during DAP, the enlargement of

  12. Effect of lignin content on changes occurring in poplar cellulose ultrastructure during dilute acid pretreatment

    DOE PAGES

    Sun, Qining; Foston, Marcus; Meng, Xianzhi; ...

    2014-10-14

    Obtaining a better understanding of the complex mechanisms occurring during lignocellulosic deconstruction is critical to the continued growth of renewable biofuel production. A key step in bioethanol production is thermochemical pretreatment to reduce plant cell wall recalcitrance for downstream processes. Previous studies of dilute acid pretreatment (DAP) have shown significant changes in cellulose ultrastructure that occur during pretreatment, but there is still a substantial knowledge gap with respect to the influence of lignin on these cellulose ultrastructural changes. This study was designed to assess how the presence of lignin influences DAP-induced changes in cellulose ultrastructure, which might ultimately have largemore » implications with respect to enzymatic deconstruction efforts. Native, untreated hybrid poplar (Populus trichocarpa x Populus deltoids) samples and a partially delignified poplar sample (facilitated by acidic sodium chlorite pulping) were separately pretreated with dilute sulfuric acid (0.10 M) at 160°C for 15 minutes and 35 minutes, respectively . Following extensive characterization, the partially delignified biomass displayed more significant changes in cellulose ultrastructure following DAP than the native untreated biomass. With respect to the native untreated poplar, delignified poplar after DAP (in which approximately 40% lignin removal occurred) experienced: increased cellulose accessibility indicated by increased Simons’ stain (orange dye) adsorption from 21.8 to 72.5 mg/g, decreased cellulose weight-average degree of polymerization (DPw) from 3087 to 294 units, and increased cellulose crystallite size from 2.9 to 4.2 nm. These changes following DAP ultimately increased enzymatic sugar yield from 10 to 80%. We conclude that, overall, the results indicate a strong influence of lignin content on cellulose ultrastructural changes occurring during DAP. With the reduction of lignin content during DAP, the enlargement of

  13. Fuel ethanol production from corn stover under optimized dilute phosphoric acid pretreatment and enzymatic hydrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethanol is a renewable oxygenated fuel. Dilute acid pretreatment is a promising pretreatment technology for conversion of lignocellulosic biomass to fuel ethanol. Generation of fermentable sugars from corn stover involves pretreatment and enzymatic saccharification. Pretreatment is crucial as nat...

  14. Separation of furans and carboxylic acids from sugars in dilute acid rice straw hydrolyzates by nanofiltration.

    PubMed

    Weng, Yu-Hsiang; Wei, Hwa-Jou; Tsai, Tsung-Yen; Lin, Ting-Hsiang; Wei, Tsong-Yang; Guo, Gia-Luen; Huang, Chin-Pao

    2010-07-01

    This work studied the concentration of hydrolyzates obtained from dilute acid hydrolysis of rice straw using nanofiltration (NF). In order to minimize the Donnan exclusion effect of the membrane, the hydrolyzate solution was controlled at low pH value. Negative retentions of both furans and carboxylic acids were observed. The maximum separation factor of acetic acid over xylose was 49, while the maximum separation factor of acetic acid over arabinose was 52, when the system was operated at pH 2.9 and an applied pressure of 24.5-34.3 bar. The separation factors of inhibitors over glucose became infinity due to the complete retention of glucose. The separation performance decreased when the operating temperature was increased from 25 to 40 degrees C. The flux deterioration was recovered by flushing with 0.01 N of NaOH and water.

  15. Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

    PubMed

    Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

    2003-05-16

    The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

  16. Computational study of the hydration of sulfuric acid dimers: implications for acid dissociation and aerosol formation.

    PubMed

    Temelso, Berhane; Phan, Thuong Ngoc; Shields, George C

    2012-10-04

    We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H(2)SO(4))(2)(H(2)O)(n) where n = 0-6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature for a system consisting of two sulfuric acid molecules and up to six waters. At 0 K, a cluster of two sulfuric acid molecules and one water remains undissociated. Addition of a second water begins the deprotonation of the first sulfuric acid leading to the di-ionic species (the bisulfate anion HSO(4)(-), the hydronium cation H(3)O(+), an undissociated sulfuric acid molecule, and a water). Upon the addition of a third water molecule, the second sulfuric acid molecule begins to dissociate. For the (H(2)SO(4))(2)(H(2)O)(3) cluster, the di-ionic cluster is a few kcal mol(-1) more stable than the neutral cluster, which is just slightly more stable than the tetra-ionic cluster (two bisulfate anions, two hydronium cations, and one water). With four water molecules, the tetra-ionic cluster, (HSO(4)(-))(2)(H(3)O(+))(2)(H(2)O)(2), becomes as favorable as the di-ionic cluster H(2)SO(4)(HSO(4)(-))(H(3)O(+))(H(2)O)(3) at 0 K. Increasing the temperature favors the undissociated clusters, and at room temperature we predict that the di-ionic species is slightly more favorable than the neutral cluster once three waters have been added to the cluster. The tetra-ionic species competes with the di-ionic species once five waters have been added to the cluster. The thermodynamics of stepwise hydration of sulfuric acid dimer is similar to that of the monomer; it is favorable up to n = 4-5 at 298 K. A much more thermodynamically favorable pathway forming sulfuric acid dimer hydrates is through the combination of sulfuric acid monomer hydrates, but the low concentration of sulfuric acid relative to

  17. 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.

  18. 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.

  19. 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

  20. Phenol-Sulfuric Acid Method for Total Carbohydrates

    NASA Astrophysics Data System (ADS)

    Nielsen, S. Suzanne

    The phenol-sulfuric acid method is a simple and rapid colorimetric method to determine total carbohydrates in a sample. The method detects virtually all classes of carbohydrates, including mono-, di-, oligo-, and polysaccharides. Although the method detects almost all carbohydrates, the absorptivity of the different carbohydrates varies. Thus, unless a sample is known to contain only one carbohydrate, the results must be expressed arbitrarily in terms of one carbohydrate.

  1. A critique of homogeneous freezing measurements of aqueous sulfuric acid

    NASA Astrophysics Data System (ADS)

    Alofs, Darryl J.; Vandike, John L.

    2000-08-01

    Two laboratory measurements of homogeneous freezing of aqueous sulfuric acid particles are critiqued: The first by Bertram et al., 1996, J. Phys. Chem., vol. 100, pp. 2376-2383: the second by Koop et al., 1998, J. Phys. Chem. A, vol. 102, pp. 8924-8931. Calculations for a proposed experimental artifact are inconclusive for Bertram et al. A proposed artifact for Koop et al. is shown to be insignificant.

  2. COS in the stratosphere. [sulfuric acid aerosol precursor

    NASA Technical Reports Server (NTRS)

    Inn, E. C. Y.; Vedder, J. F.; Tyson, B. J.; Ohara, D.

    1979-01-01

    Carbonyl sulfide (COS) has been detected in the stratosphere, and mixing ratio measurements are reported for altitudes of 15.2 to 31.2 km. A large volume, cryogenic sampling system mounted on board a U-2 aircraft has been used for lower stratosphere measurements and a balloon platform for measurement at 31.2 km. These observations and measurements strongly support the concept that stratospheric COS is an important precursor in the formation of sulfuric acid aerosols.

  3. Recovery of rhenium from sulfuric acid solutions with activated coals

    SciTech Connect

    Troshkina, I.D.; Naing, K.Z.; Ushanova, O.N.; P'o, V.; Abdusalomov, A.A.

    2006-09-15

    Equilibrium and kinetic characteristics of rhenium sorption from sulfuric acid solutions (pH 2) by activated coals produced from coal raw materials (China) were studied. Constants of the Henry equation describing isotherms of rhenium sorption by activated coals were calculated. The effective diffusion coefficients of rhenium in the coals were determined. The dynamic characteristics of rhenium sorption and desorption were determined for the activated coal with the best capacity and kinetic characteristics.

  4. Sulfuric acid intercalated graphite oxide for graphene preparation.

    PubMed

    Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

    2013-12-06

    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 μm 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.

  5. Sulfuric Acid Speleogenesis: Microbial Karst and Microbial Crust

    NASA Astrophysics Data System (ADS)

    Engel, A. S.; Bennett, P. C.; Stern, L. A.

    2001-12-01

    Sulfuric acid speleogenesis is a fundamental mechanism of karst formation, and is potentially responsible for the formation of some of the most extensive cave systems yet discovered. Speleogenesis occurs from the rapid dissolution of the host limestone by sulfuric acid produced from biotic and abiotic sulfide oxidation, and with the release of carbon dioxide, secondary gypsum crusts form. This crust develops predominately on the cave walls, often preserving original bedding indicators, until it finally collapses under its own weight to expose fresh limestone for dissolution. While this general speleogenetic process can be inferred from secondary residues in some caves, directly observing this process is difficult, and involves entry into an extreme environment with toxic atmospheres and low pH solutions. Kane Cave, Big Horn County, WY, offers the unique opportunity to study microbe-rock interactions directly. Kane Cave presently contains 3 springs that discharge hydrogen sulfide-rich waters, supporting thick subaqueous mats of diverse microbial communities in the stream passage. Condensation droplets and elemental sulfur form on subaerially exposed gypsum surfaces. Droplets have an average pH of 1.7, and are dominated by dissolved sulfate, Ca, Mg, Al, and Si, with minor Sr and Fe, and trace Mn and U. SEM and EDS examination of the crusts reveal the presence of C, O, and S, as well as authigenic, doubly-terminated quartz crystals. An average δ 13C value of -36 ‰ suggests that the crusts are biogenic and are composed of chemoautotrophic microorganisms. Enrichment cultures of biofilms and acid droplets rapidly produce sulfuric acid, demonstrating the dominance of sulfur-oxidizing bacteria. Colonization of gypsum surfaces by acidophilic microorganisms enhances acid dissolution of the limestone, and hence the growth of the cave itself. Limestone dissolution also results in mineralized crusts and biofilms that accumulate insoluble residues, which serve as sources of

  6. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    SciTech Connect

    Wang, S.W.

    1980-06-01

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 313/sup 0/K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 298/sup 0/K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory.

  7. 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.

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

    SciTech Connect

    Schuster, P.F.; Reddy, M.M. ); Sherwood, S.I. )

    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.

  9. Coulometric determination of berkelium in sulfuric acid and nitric acid solutions

    SciTech Connect

    Timofeev, G.A.; Chistyakov, V.M.; Erin, E.A.

    1987-03-01

    Results are reported on the study and quantitative determination of berkelium by the coulometric method in 1 M sulfuric acid, in solutions of nitric acid, and in mixtures of these acids. The best results in the determination of berkelium were obtained in solutions of a mixture of nitric and sulfuric acids. In 1 M HNO/sub 3/ + 0.1 M H/sub 2/SO/sub 4/ solutions, berkelium can be determined with an accuracy within approx. +/- 2%, when its content is 10 ..mu..g/ml.

  10. Sulfuric Acid and Soot Particle Formation in Aircraft Exhaust

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf F.; Verma, S.; Ferry, G. V.; Howard, S. D.; Vay, S.; Kinne, S. A.; Baumgardner, D.; Dermott, P.; Kreidenweis, S.; Goodman, J.; Gore, Waren J. Y. (Technical Monitor)

    1997-01-01

    A combination of CN counts, Ames wire impactor size analyses and optical particle counter data in aircraft exhaust results in a continuous particle size distribution between 0.01 micrometer and 1 micrometer particle radius sampled in the exhaust of a Boeing 757 research aircraft. The two orders of magnitude size range covered by the measurements correspond to 6-7 orders of magnitude particle concentration. CN counts and small particle wire impactor data determine a nucleation mode, composed of aircraft-emitted sulfuric acid aerosol, that contributes between 62% and 85% to the total aerosol surface area and between 31% and 34% to its volume. Soot aerosol comprises 0.5% of the surface area of the sulfuric acid aerosol. Emission indices are: EIH2SO4 = 0.05 g/kgFUEL and (0.2-0.5) g/kgFUEL (for 75 ppmm and 675 ppmm fuel-S, respectively), 2.5E4sulfur (gas) to H2SO4 (particle) conversion efficiency is between 10% and 25%.

  11. High ethanol fermentation performance of the dry dilute acid pretreated corn stover by an evolutionarily adapted Saccharomyces cerevisiae strain.

    PubMed

    Qureshi, Abdul Sattar; Zhang, Jian; Bao, Jie

    2015-01-01

    Ethanol fermentation was investigated at the high solids content of the dry dilute sulfuric acid pretreated corn stover feedstock using an evolutionary adapted Saccharomyces cerevisiae DQ1 strain. The evolutionary adaptation was conducted by successively transferring the S. cerevisiae DQ1 cells into the inhibitors containing corn stover hydrolysate every 12h and finally a stable yeast strain was obtained after 65 days' continuous adaptation. The ethanol fermentation performance using the adapted strain was significantly improved with the high ethanol titer of 71.40 g/L and the high yield of 80.34% in the simultaneous saccharification and fermentation (SSF) at 30% solids content. No wastewater was generated from pretreatment to fermentation steps. The results were compared with the published cellulosic ethanol fermentation cases, and the obvious advantages of the present work were demonstrated not only at the high ethanol titer and yield, but also the significant reduction of wastewater generation and potential cost reduction.

  12. A Development of Ceramics Cylinder Type Sulfuric Acid Decomposer for Thermo-Chemical Iodine-Sulfur Process Pilot Plant

    SciTech Connect

    Hiroshi Fukui; Isao Minatsuki; Kazuo Ishino

    2006-07-01

    The hydrogen production method applying thermo-chemical Iodine-Sulfur process (IS process) which uses a nuclear high temperature gas cooled reactor is world widely greatly concerned from the view point of a combination as a clean method, free carbon dioxide in essence. In this process, it is essential a using ceramic material, especially SiC because a operation condition of this process is very corrosive due to a sulfuric acid atmosphere with high temperature and high pressure. In the IS process, a sulfuric acid decomposer is the key component which performs evaporating of sulfuric acid from liquid to gas and disassembling to SO{sub 2} gas. SiC was selected as ceramic material to apply for the sulfuric acid decomposer and a new type of binding material was also developed for SiC junction. This technology is expected to wide application not only for a sulfuric acid decomposer but also for various type components in this process. Process parameters were provided as design condition for the decomposer. The configuration of the sulfuric acid decomposer was studied, and a cylindrical tubes assembling type was selected. The advantage of this type is applicable for various type of components in the IS process due to manufacturing with using only simple shape part. A sulfuric acid decomposer was divided into two regions of the liquid and the gaseous phase of sulfuric acid. The thermal structural integrity analysis was studied for the liquid phase part. From the result of this analysis, it was investigated that the stress was below the strength of the breakdown probability 1/100,000 at any position, base material or junction part. The prototype model was manufactured, which was a ceramic portion in the liquid phase part, comparatively complicated configuration, of a sulfuric acid decomposer. The size of model was about 1.9 m in height, 1.0 m in width. Thirty-six cylinders including inlet and outlet nozzles were combined and each part article was joined using the new binder

  13. A Development of Ceramics Cylinder Type Sulfuric Acid Decomposer for Thermo-Chemical Iodine-Sulfur Process Pilot Plant

    NASA Astrophysics Data System (ADS)

    Minatsuki, Isao; Fukui, Hiroshi; Ishino, Kazuo

    The hydrogen production method applying thermo-chemical Iodine-Sulfur process (IS process) which uses a nuclear high temperature gas cooled reactor is world widely greatly concerned from the view point of a combination as a clean method, free carbon dioxide in essence. In this process, it is essential a using ceramic material, especially SiC because a operation condition of this process is very corrosive due to a sulfuric acid atmosphere with high temperature and high pressure. In the IS process, a sulfuric acid decomposer is the key component which performs evaporating of sulfuric acid from liquid to gas and disassembling to SO2 gas. SiC was selected as ceramic material to apply for the sulfuric acid decomposer and a new type of binding material was also developed for SiC junction. This technology is expected to wide application not only for a sulfuric acid decomposer but also for various type components in this process. Process parameters were provided as design condition for the decomposer. The configuration of the sulfuric acid decomposer was studied, and a cylindrical tubes assembling type was selected. The advantage of this type is applicable for various type of components in the IS process due to manufacturing with using only simple shape part. A sulfuric acid decomposer was divided into two regions of the liquid and the gaseous phase of sulfuric acid. The thermal structural integrity analysis was studied for the liquid phase part. From the result of this analysis, it was investigated that the stress was below the strength of the breakdown probability 1/100,000 at any position, base material or junction part. The prototype model was manufactured, which was a ceramic portion in the liquid phase part, comparatively complicated configuration, of a sulfuric acid decomposer. The size of model was about 1.9m in height, 1.0m in width. Thirty-six cylinders including inlet and outlet nozzles were combined and each part article was joined using the new binder (slurry

  14. Real-time investigations of Pt(111) surface transformations in sulfuric acid solutions.

    PubMed

    Braunschweig, Björn; Mukherjee, Prabuddha; Dlott, Dana D; Wieckowski, Andrzej

    2010-10-13

    We present the first broadband sum-frequency generation (SFG) spectra of adlayers from sulfuric acid solutions on Pt(111) surfaces and reveal surface transformations of (bi)sulfate anions in unprecedented detail. SFG amplitudes, bandwidth, and electrochemical Stark tuning of (bi)sulfate vibrational bands centered at 1250-1290 cm(-1) strongly depend on the applied potential and are correlated with prominent voltammetric features. (Bi)sulfate adlayers on Pt(111) are important model systems for weak, specific adsorption of anions on catalytically active surfaces. Although the existence of surface transformations on Pt(111) in dilute H(2)SO(4) solutions has been established by previous studies, so far they have not been observed with surface vibrational spectroscopy. Our results confirm previous reports of a surface transformation at 0.21 V and provide new information on a second transformation at 0.5 V due to surface hydroxyl formation and rearrangement of the electric double layer.

  15. Heterogeneous Chemistry of HONO on Liquid Sulfuric Acid: A New Mechanism of Chlorine Activation on Stratospheric Sulfate Aerosols

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

    1996-01-01

    Heterogeneous chemistry of nitrous acid (HONO) on liquid sulfuric acid (H2SO4) Was investigated at conditions that prevail in the stratosphere. The measured uptake coefficient (gamma) of HONO on H2SO4 increased with increasing acid content, ranging from 0.03 for 65 wt % to about 0.1 for 74 wt %. In the aqueous phase, HONO underwent irreversible reaction with H2SO4 to form nitrosylsulfuric acid (NO(+)HSO4(-). At temperatures below 230 K, NO(+)HSO4(-) was observed to be stable and accumulated in concentrated solutions (less than 70 wt % H2SO4) but was unstable and quickly regenerated HONO in dilute solutions (less than 70 wt %). HCl reacted with HONO dissolved in sulfuric acid, releasing gaseous nitrosyl chloride (ClNO). The reaction probability between HCl and HONO varied from 0.01 to 0.02 for 60-72 wt % H2SO4. In the stratosphere, ClNO photodissociates rapidly to yield atomic chlorine, which catalytically destroys ozone. Analysis of the laboratory data reveals that the reaction of HCl with HONO on sulfate aerosols can affect stratospheric ozone balance during elevated sulfuric acid loadings after volcanic eruptions or due to emissions from the projected high-speed civil transport (HSCT). The present results may have important implications on the assessment of environmental acceptability of HSCT.

  16. 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

  17. Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design

    NASA Astrophysics Data System (ADS)

    Peck, Michael S.

    Increasing global climate change has been driven by greenhouse gases emissions originating from the combustion of fossil fuels. Clean burning hydrogen has the potential to replace much of the fossil fuels used today reducing the amount of greenhouse gases released into the atmosphere. The sulfur iodine and hybrid sulfur thermochemical cycles coupled with high temperature heat from advanced nuclear reactors have shown promise for economical large-scale hydrogen fuel stock production. Both of these cycles employ a step to decompose sulfuric acid to sulfur dioxide. This decomposition step occurs at high temperatures in the range of 825°C to 926°C dependent on the catalysis used. Successful commercial implementation of these technologies is dependent upon the development of suitable materials for use in the highly corrosive environments created by the decomposition products. Boron treated diamond film was a potential candidate for use in decomposer process equipment based on earlier studies concluding good oxidation resistance at elevated temperatures. However, little information was available relating the interactions of diamond and diamond films with sulfuric acid at temperatures greater than 350°C. A laboratory scale sulfuric acid decomposer simulator was constructed at the Nuclear Science and Engineering Institute at the University of Missouri-Columbia. The simulator was capable of producing the temperatures and corrosive environments that process equipment would be exposed to for industrialization of the sulfur iodide or hybrid sulfur thermochemical cycles. A series of boron treated synthetic diamonds were tested in the simulator to determine corrosion resistances and suitability for use in thermochemical process equipment. These studies were performed at twenty four hour durations at temperatures between 600°C to 926°C. Other materials, including natural diamond, synthetic diamond treated with titanium, silicon carbide, quartz, aluminum nitride, and Inconel

  18. 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

  19. 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

  20. 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

    ... amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721... Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid... benzenesulfonic acid and sulfuric acid (PMNs P-89-703, P-89-755, and P-89-756) are subject to reporting under...

  1. 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

    ... amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721... Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid... benzenesulfonic acid and sulfuric acid (PMNs P-89-703, P-89-755, and P-89-756) are subject to reporting under...

  2. 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

    ... amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721... Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid... benzenesulfonic acid and sulfuric acid (PMNs P-89-703, P-89-755, and P-89-756) are subject to reporting under...

  3. 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

    ... amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721... Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid... benzenesulfonic acid and sulfuric acid (PMNs P-89-703, P-89-755, and P-89-756) are subject to reporting under...

  4. 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

    ... amines with a substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220 Section 721... Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric acid... benzenesulfonic acid and sulfuric acid (PMNs P-89-703, P-89-755, and P-89-756) are subject to reporting under...

  5. 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

  6. Sulfuric acid pretreatment and enzymatic hydrolysis of photoperiod sensitive sorghum for ethanol production.

    PubMed

    Xu, Feng; Shi, Yong-Cheng; Wu, Xiaorong; Theerarattananoon, Karnnalin; Staggenborg, Scott; Wang, Donghai

    2011-05-01

    Photoperiod sensitive (PS) sorghum, with high soluble sugar content, high mass yield and high drought tolerance in dryland environments, has great potential for bioethanol production. The effect of diluted sulfuric acid pretreatment on enzymatic hydrolysis was investigated. Hydrolysis efficiency increased from 78.9 to 94.4% as the acid concentration increased from 0.5 to 1.5%. However, the highest total glucose yield (80.3%) occurred at the 1.0% acid condition because of the significant cellulose degradation at the 1.5% concentration. Synchrotron wide-angle X-ray diffraction was used to study changes of the degree of crystallinity. With comparison of cellulosic crystallinity and adjusted cellulosic crystallinity, the crystalline cellulose decreased after low acidic concentration (0.5%) applied, but did not change significantly, as the acid concentration increased. Scanning electron microscopy was also employed to understand how the morphological structure of PS sorghum changed after pretreatment. Under current processing conditions, the total ethanol yield is 74.5% (about 0.2 g ethanol from 1 g PS sorghum). A detail mass balance was also provided.

  7. Sulfuric Acid Pretreatment and Enzymatic Hydrolysis of Photoperiod Sensitvie Sorghum for Ethanol Production

    SciTech Connect

    F Xu; Y Shi; X Wu

    2011-12-31

    Photoperiod sensitive (PS) sorghum, with high soluble sugar content, high mass yield and high drought tolerance in dryland environments, has great potential for bioethanol production. The effect of diluted sulfuric acid pretreatment on enzymatic hydrolysis was investigated. Hydrolysis efficiency increased from 78.9 to 94.4% as the acid concentration increased from 0.5 to 1.5%. However, the highest total glucose yield (80.3%) occurred at the 1.0% acid condition because of the significant cellulose degradation at the 1.5% concentration. Synchrotron wide-angle X-ray diffraction was used to study changes of the degree of crystallinity. With comparison of cellulosic crystallinity and adjusted cellulosic crystallinity, the crystalline cellulose decreased after low acidic concentration (0.5%) applied, but did not change significantly, as the acid concentration increased. Scanning electron microscopy was also employed to understand how the morphological structure of PS sorghum changed after pretreatment. Under current processing conditions, the total ethanol yield is 74.5% (about 0.2 g ethanol from 1 g PS sorghum). A detail mass balance was also provided.

  8. Comparison between the single-bubble sonoluminescences in sulfuric acid and in water

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Chen, Weizhong; Gao, Xianxian; Liang, Yue

    2009-02-01

    Single-bubble sonoluminescence (SBSL) is achieved with strong stability in sulfuric acid solutions. Bubble dynamics and the SBSL spectroscopy in the sulfuric acid solutions with different concentrations are studied with phase-locked integral stroboscopic photography method and a spectrograph, respectively. The experimental results are compared with those in water. The SBSL in sulfuric acid is brighter than that in water. One of the most important reasons for that is the larger viscosity of sulfuric acid, which results in the larger ambient radius and thus the more contents of luminous material inside the bubble. However, sonoluminescence bubble’s collapse in sulfuric acid is less violent than that in water, and the corresponding blackbody radiation temperature of the SBSL in sulfuric acid is lower than that in water.

  9. Sulfuric acid cloud interpretation of the infrared spectrum of Venus

    NASA Technical Reports Server (NTRS)

    Martonchik, J. V.

    1974-01-01

    Sulfuric acid single-cloud models are compared with the Venus spectrum in the 8-14 micron region. The results indicate that a cloud composed of a 75 percent H2SO4 solution and with a particle density of 100 per cu cm is in good agreement with observations. In addition to explaining the 11.2 micron absorption, this model also predicts an absorption feature at 16.7 microns which should be detectable if the observation is made from an aircraft.

  10. A rotamer energy level study of sulfuric acid.

    PubMed

    Partanen, Lauri; Pesonen, Janne; Sjöholm, Elina; Halonen, Lauri

    2013-10-14

    It is a common approach in quantum chemical calculations for polyatomic molecules to rigidly constrain some of the degrees of freedom in order to make the calculations computationally feasible. However, the presence of the rigid constraints also affects the kinetic energy operator resulting in the frozen mode correction, originally derived by Pesonen [J. Chem. Phys. 139, 144310 (2013)]. In this study, we compare the effects of this correction to several different approximations to the kinetic energy operator used in the literature, in the specific case of the rotamer energy levels of sulfuric acid. The two stable conformers of sulfuric acid are connected by the rotations of the O-S-O-H dihedral angles and possess C2 and Cs symmetry in the order of increasing energy. Our results show that of the models tested, the largest differences with the frozen mode corrected values were obtained by simply omitting the passive degrees of freedom. For the lowest 17 excited states, this inappropriate treatment introduces an increase of 9.6 cm(-1) on average, with an increase of 8.7 cm(-1) in the zero-point energies. With our two-dimensional potential energy surface calculated at the CCSD(T)-F12a/VDZ-F12 level, we observe a radical shift in the density of states compared to the harmonic picture, combined with an increase in zero point energy. Thus, we conclude that the quantum mechanical inclusion of the different conformers of sulfuric acid have a significant effect on its vibrational partition function, suggesting that it will also have an impact on the computational values of the thermodynamic properties of any reactions where sulfuric acid plays a role. Finally, we also considered the effect of the anharmonicities for the other vibrational degrees of freedom with a VSCF-calculation at the DF-MP2-F12/VTZ-F12 level of theory but found that the inclusion of the other conformer had the more important effect on the vibrational partition function.

  11. Use of Empty Fruit Bunches from the oil palm for bioethanol production: a thorough comparison between dilute acid and dilute alkali pretreatment.

    PubMed

    Chiesa, S; Gnansounou, E

    2014-05-01

    In the present work, two pretreatment techniques using either dilute acid (H2SO4) or dilute alkali (NaOH) have been compared for producing bioethanol from Empty Fruit Bunches (EFBs) from oil palm tree, a relevant feedstock for tropical countries. Treatments' performances under different conditions have been assessed and statistically optimized with respect to the response upon standardized enzymatic saccharification. The dilute acid treatment performed at optimal conditions (161.5°C, 9.44 min and 1.51% acid loading) gave 85.5% glucose yield, comparable to those of other commonly investigated feedstocks. Besides, the possibility of using fibers instead of finely ground biomass may be of economic interest. Oppositely, treatment with dilute alkali has shown lower performances under the conditions explored, most likely given the relatively significant lignin content, suggesting that the use of stronger alkali regime (with the associated drawbacks) is unavoidable to improve the performance of this treatment.

  12. 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

  13. Solubility of HBr in sulfuric acid at stratospheric temperatures

    SciTech Connect

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

    1995-04-20

    The solubility of HBr in 54 to 72 wt % sulfuric acid at low temperatures (200 to 240 K) was measured using two different experimental techniques. In the first, the time dependence of the uptake coefficient of HBr was measured in a Knudsen cell reactor and analyzed to give the effective Henry`s law coefficient. In the second, equilibrium vapor pressures of HBr (gas) over solutions containing known concentrations of HBr (dissolved) were measured. The two techniques were in good agreement. Typical values of the effective Henry`s law coefficient at 220 K were 1.5 x 10{sup 7} M/atm for 54 wt %, 2.2 x 10{sup 6} M/atm for 60 wt %, 1.5 x 10{sup 5} M/atm for 66 wt %, and 8.5 x 10{sup 3} M/atm for 72 wt % sulfuric acid. The measured solubilities combined with the stratospheric gas phase concentration of HBr indicate that very little HBr will be dissolved in stratospheric sulfate aerosol particles. 28 refs., 4 figs., 2 tabs.

  14. Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks

    NASA Technical Reports Server (NTRS)

    Baldwin, A. C.; Golden, D. M.

    1979-01-01

    The reaction probabilities of various atmospheric species incident on a bulk sulfuric acid surface are measured in order to determine the role of sulfuric acid aerosols as pollutant sinks. Reaction products and unreacted starting materials leaving a Knudsen cell flow reactor after collision at 300 K with a H2SO4 surface or a soot surface were detected by mass spectrometry. Significant collision reaction probabilities are observed on a H2SO4 surface for H2O2, HNO3, HO2NO2, ClONO2, N2O5, H2O and NH3, and on soot for NH3. Estimates of the contribution of heterogeneous reactions to pollutant removal under atmospheric conditions indicate that while aerosol removal in the stratosphere is insignificant (loss rate constants approximately 10 to the -10th/sec), heterogeneous reactions may be the dominant loss process for several tropospheric species (loss rate constant approximately 10 to the -5th/sec, comparable to photolysis rate constants).

  15. Laboratory measurements of heterogeneous reactions on sulfuric acid surfaces

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Manion, Jeffrey A.; Golden, David M.; Tolbert, Margaret A.

    1994-01-01

    Increasing evidence from field, modeling, and laboratory studies suggests that heterogeneous reactions on stratospheric sulfate aerosol particles may contribute to global ozone depletion. Using a Knudsen cell reactor technique, the authors have studied the uptake, reactivity, and solubility of several trace atmospheric species on cold sulfuric acid surfaces representative of stratospheric aerosol particles. The results suggest that the heterogeneous conversion of N2O5 to HNO3 is fast enough to significantly affect the partitioning of nitrogen species in the global stratosphere and thus contribute to global ozone depletion. The hydrolysis of ClONO2 is slower and unlikely to be important under normal conditions at midlatitudes. The solubilities of HCl and HNO3 in sulfuric acid down to 200 K were found to be quite low. For HCl, this means that little HCl is available for reaction on the surfaces of stratospheric sulfate aerosol particles. The low solubility of HNO3 means that this product of heterogeneous reactions will enter the gas phase, and the denitrification observed in polar regions is unlikely to occur in the global stratosphere.

  16. Sulfuric Acid Monohydrate: Formation and Heterogeneous Chemistry in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

    1995-01-01

    We have investigated some thermodynamic properties (i.e., freezing/melting points) and heterogeneous chemistry of sulfuric acid monohydrate (SAM, H2SO4.H2O), using a fast flow reactor coupled to a quadrupole mass spectrometer. The freezing point observations of thin liquid sulfuric acid films show that for acid contents between 75 and 85 wt % the monohydrate crystallizes readily at temperatures between 220 and 240 K on a glass substrate. Once formed, SAM can be thermodynamically stable in the H2O partial pressure range of (1-4) x 10(exp -4) torr and in the temperature range of 220-240 K. For a constant H2O partial pressure, lowering the temperature causes SAM to melt when the temperature and water partial pressure conditions are out of its stability regime. The reaction probability measurements indicate that the hydrolysis of N2O5 is significantly suppressed owing to the formation of crystalline SAM: The reaction probability on water-rich SAM (with higher relative humidity, or RH) is of the order of 10(exp -3) at 210 K and decreases by more than an order of magnitude for the acid-rich form (with lower RH). The hydrolysis rate of ClONO2 on water-rich SAM is even smaller, of the order of 10(exp -4) at 195 K. These reported values on crystalline SAM are much smaller than those on liquid solutions. No enhancement of these reactions is observed in the presence of HCl vapor at the stratospheric concentrations. In addition, Brunauer, Emmett, and Teller analysis of gas adsorption isotherms and photomicrography have been performed to characterize the surface roughness and porosities of the SAM substrate. The results suggest the possible formation of SAM in some regions of the middle- or low-latitude stratosphere and, consequently, much slower heterogeneous reactions on the frozen aerosols.

  17. Ion-exclusion chromatographic behavior of aliphatic carboxylic acids and benzenecarboxylic acids on a sulfonated styrene--divinylbenzene co-polymer resin column with sulfuric acid containing various alcohols as eluent.

    PubMed

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

    2003-05-16

    The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent.

  18. Short-term respiratory effects of sulfuric acid in fog: a laboratory study of healthy and asthmatic volunteers

    SciTech Connect

    Avol, E.L.; Linn, W.S.; Wightman, L.H.; Whynot, J.D.; Anderson, K.R.; Hackney, J.D.

    1988-03-01

    To explore short-term respiratory health risks from acid-polluted fog, 22 normal and 22 asthmatic adult volunteers were exposed in an environmental control chamber to light fogs containing nominally 0, 500, 1000, and 2000 ..mu..g/m/sup 3/ of sulfuric acid. Fog was produced by atomizing dilute acid solution into purified air humidified to near 100% by stem injection. Exposures were administered in random order at 1-week intervals, lasted 1 h, and included three 10-min periods of moderately heavy exercise. Responses were measured in terms of forced expiratory function, airway resistance, irritant symptoms, and bronchial reactivity to methacholine aerosol. Sulfuric acid per se showed no more than a slight effect on pulmonary function, even at the highest concentration. Asthmatics experienced bronchoconstriction, attributable to exercise, under all exposure conditions. Despite the lack of substantial function changes, modest statistically significant increases in respiratory symptoms occurred with increasing acid concentrations. This unusual response pattern suggests that acid fog effects occur via a mechanism somewhat different from those which govern responses to irritant gases like SO/sub 2/ or O/sub 3/. To the extent these results are relevant to ambient acid fog exposures, they predict that no pulmonary dysfunction, and only slight respiratory symptoms if any, are likely to occur.

  19. 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.

  20. A new test procedure for biogenic sulfuric acid corrosion of concrete

    PubMed

    Vincke; Verstichel; Monteny; Verstraete

    1999-01-01

    A new test method is described for biogenic sulfuric acid corrosion of concrete, more specifically in sewer conditions. The aim of the new test method is the development of an accelerated and reproducible procedure for monitoring the resistance of different types of concrete with regard to biogenic sulfuric acid corrosion. This experimental procedure reflects worst case conditions by providing besides H2S, also an enrichment of thiobacilli and biologically produced sulfur. By simulating the cyclic processes occurring in sewer pipes, significant differences between concrete mixtures could be detected after 51 days. Concrete modified by a styrene-acrylic ester polymer demonstrated a higher resistance against biogenic sulfuric acid attack.

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

    SciTech Connect

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

    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 to initiate the investigation of the mechanisms that result in this enhancement. 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 Fe{sup 2+} ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe{sup 2+} ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe{sup 2+} ion pretreatment, in which delamination and fibrillation of the cell wall were observed. 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.

  2. Sulfur redox reactions: Hydrocarbons, native sulfur, Mississippi Valley-type deposits, and sulfuric acid karst in the Delaware Basin, New Mexico and Texas

    SciTech Connect

    Hill, C.A.

    1995-02-01

    Hydrocarbons, native sulfur, Mississippi Valley-type (MVT) deposits, and sulfuric acid karst in the Delaware Basin, southeastern New Mexico, and west Texas, USA, are all genetically related through a series of sulfur redox reactions. The relationship began with hydrocarbons in the basin that reacted with sulfate ions from evaporite rock to produce isotopically light ({delta}{sup 34}S = -22 to -12) H{sub 2}S and bioepigenetic limestone (castiles). This light H{sub 2}S was then oxidized at the redox interface to produce economic native sulfur deposits ({delta}{sup 34}S = -15 to +9) in the castiles, paleokarst, and along graben-boundary faults. This isotopically light H{sub 2}S also migrated from the basin into its margins to accumulate in structural (anticlinal) and stratigraphic (Yates siltstone) traps, where it formed MVT deposits within the zone of reduction ({delta}{sup 34}S = -15 to +7). Later in time, in the zone of oxidation, this H{sub 2}S reacted with oxygenated water to produce sulfuric acid, which dissolved the caves (e.g., Carlsbad Cavern and Lechuguilla Cave, Guadalupe Mountains). Massive gypsum blocks on the floors of the caves ({delta}{sup 34}S = -25 to +4) were formed as a result of this reaction. The H{sub 2}S also produced isotopically light cave sulfur ({delta}{sup 34}S = -24 to -15), which is now slowly oxidizing to gypsum in the presence of vadose drip water. 16 refs., 10 figs.

  3. The use of dilute hydrochloric acid and cimetidine to reverse severe metabolic alkalosis.

    PubMed

    Rowlands, B J; Tindall, S F; Elliott, D J

    1978-02-01

    Two cases of severe metabolic alkalosis associated with gastric hypersecretion were successfully treated with dilute hydrochloric acid and a histamine H2-receptor antagonist given by intravenous infusion. This combined therapy with electrolyte replacement and suppression of gastric secretion is valuable in the control of this serious metabolic abnormality when conventional treatment is unsuccessful or contraindicated.

  4. High temperature dilute phosphoric acid pretreatment of corn stover for furfural and ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Furfural was produced from corn stover by one stage pretreatment process using dilute H3PO4 and solid residues following furfural production were used for ethanol production by Saccharomyces cerevisiae NRRL- Y2034. A series of experiments were conducted at varied temperatures (140-200 oC) and acid ...

  5. Comparison of Dilute Acid and Ionic Liquid Pretreatment of Switchgrass: Biomass Recalcitrance, Delignification and Enzymatic Saccharification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficiency of two biomass pretreatment technologies, dilute acid hydrolysis and dissolution in an ionic liquid, are compared in terms of delignification, saccharification efficiency and saccharide yields with switchgrass serving as a model bioenergy crop. When subject to ionic liquid pretreatme...

  6. Enthalpy changes upon dilution and ionization of poly(L-glutamic acid) in aqueous solutions.

    PubMed

    Godec, Andrej; Skerjanc, Joze

    2005-07-14

    The enthalpy changes accompanying the dilution and ionization of poly(L-glutamic acid) in water have been measured at 25 degrees C for two degrees of polymerization (DP = 115 and DP = 480) at various degrees of ionization, alpha, for a concentration range from about 0.2 to 0.002 monomol/L. The heat of dilution displays an unusual dependence on the degree of ionization, which is in sharp contrast to the behavior of other weak carboxylic polyelectrolytes, such as poly(acrylic acid). The exothermic heat effects observed at low values of alpha become endothermic for the region where the helix-coil transition is most pronounced, and for high degrees of ionization, they are exothermic again. Evidently, an endothermic heat effect, produced by an additional conformational transition in the dilution process, is superimposed on the exothermic enthalpy of dilution, and it overweighs the latter in the region of alpha where the conformational transition is prevailing. The calorimetric titration curve, which gives the dependence of the heat of ionization, deltaH(i), on alpha, has a maximum and is typical for poly(carboxylic acids) which undergo pH-induced conformational transition, such as poly(methacrylic acid). The values of deltaH(i) obtained at two polymer concentrations indicate that the enthalpy of ionization depends on the polypeptide concentration.

  7. Microwave assisted conversion of microcrystalline cellulose into value added chemicals using dilute acid catalyst.

    PubMed

    Ching, Teck Wei; Haritos, Victoria; Tanksale, Akshat

    2017-02-10

    One of the grand challenges of this century is to transition fuels and chemicals production derived from fossil feedstocks to renewable feedstocks such as cellulosic biomass. Here we describe fast microwave conversion of microcrystalline cellulose (MCC) in water, with dilute acid catalyst to produce valuable platform chemicals. Single 10min microwave assisted treatment was able to convert >60% of MCC, with >50mol% yield of desirable products such as glucose, HMF, furfural and levulinic acid. Recycling of residual MCC with make-up fresh MCC resulted in an overall conversion of >93% after 5 cycles while maintaining >60% conversion in each cycle. Addition of isopropanol (70%v/v) as a co-solvent increased the yields of HMF and levulinic acid. This work shows for the first time proof of concept for complete conversion of recalcitrant microcrystalline cellulose in mild conditions of low temperature, dilute acid and short residence time using energy efficient microwave technology.

  8. Unexpectedly acidic nanoparticles formed in dimethylamine-ammonia-sulfuric-acid nucleation experiments at CLOUD

    NASA Astrophysics Data System (ADS)

    Lawler, Michael J.; Winkler, Paul M.; Kim, Jaeseok; Ahlm, Lars; Tröstl, Jasmin; Praplan, Arnaud P.; Schobesberger, Siegfried; Kürten, Andreas; Kirkby, Jasper; Bianchi, Federico; Duplissy, Jonathan; Hansel, Armin; Jokinen, Tuija; Keskinen, Helmi; Lehtipalo, Katrianne; Leiminger, Markus; Petäjä, Tuukka; Rissanen, Matti; Rondo, Linda; Simon, Mario; Sipilä, Mikko; Williamson, Christina; Wimmer, Daniela; Riipinen, Ilona; Virtanen, Annele; Smith, James N.

    2016-11-01

    New particle formation driven by acid-base chemistry was initiated in the CLOUD chamber at CERN by introducing atmospherically relevant levels of gas-phase sulfuric acid and dimethylamine (DMA). Ammonia was also present in the chamber as a gas-phase contaminant from earlier experiments. The composition of particles with volume median diameters (VMDs) as small as 10 nm was measured by the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Particulate ammonium-to-dimethylaminium ratios were higher than the gas-phase ammonia-to-DMA ratios, suggesting preferential uptake of ammonia over DMA for the collected 10-30 nm VMD particles. This behavior is not consistent with present nanoparticle physicochemical models, which predict a higher dimethylaminium fraction when NH3 and DMA are present at similar gas-phase concentrations. Despite the presence in the gas phase of at least 100 times higher base concentrations than sulfuric acid, the recently formed particles always had measured base : acid ratios lower than 1 : 1. The lowest base fractions were found in particles below 15 nm VMD, with a strong size-dependent composition gradient. The reasons for the very acidic composition remain uncertain, but a plausible explanation is that the particles did not reach thermodynamic equilibrium with respect to the bases due to rapid heterogeneous conversion of SO2 to sulfate. These results indicate that sulfuric acid does not require stabilization by ammonium or dimethylaminium as acid-base pairs in particles as small as 10 nm.

  9. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.7770 Alkylphenoxypoly(oxyethylene) sulfuric acid...) The chemical substance identified as alkyl phenoxypoly(oxyethylene) sulfuric acid ester, substituted... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkylphenoxypoly(oxyethylene)...

  10. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.7770 Alkylphenoxypoly(oxyethylene) sulfuric acid...) The chemical substance identified as alkyl phenoxypoly(oxyethylene) sulfuric acid ester, substituted... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkylphenoxypoly(oxyethylene)...

  11. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.7770 Alkylphenoxypoly(oxyethylene) sulfuric acid...) The chemical substance identified as alkyl phenoxypoly(oxyethylene) sulfuric acid ester, substituted... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkylphenoxypoly(oxyethylene)...

  12. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.7770 Alkylphenoxypoly(oxyethylene) sulfuric acid...) The chemical substance identified as alkyl phenoxypoly(oxyethylene) sulfuric acid ester, substituted... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkylphenoxypoly(oxyethylene)...

  13. 40 CFR 721.7770 - Alkylphenoxypoly(oxyethylene) sulfuric acid ester, substituted amine salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.7770 Alkylphenoxypoly(oxyethylene) sulfuric acid...) The chemical substance identified as alkyl phenoxypoly(oxyethylene) sulfuric acid ester, substituted... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylphenoxypoly(oxyethylene)...

  14. 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)

  15. Correlation of Sulfuric Acid Hydrate Abundance with Charged Particle Flux at the Surface of Europa

    NASA Astrophysics Data System (ADS)

    Dalton, James B.; Paranicas, C. P.; Cassidy, T. A.; Shirley, J. H.

    2010-10-01

    The trailing hemisphere of Jupiter's moon Europa is bombarded by charged particles trapped within Jupiter's magnetosphere. Sulfur ion implantation and impacting energetic electrons strongly affect the surface chemistry of Europa. Understanding these processes is important for disentangling the extrinsic and intrinsic components of Europa's surface chemistry. In the sulfur cycle model of Carlson et al. (Science 286, 97, 1999), hydrated sulfuric acid represents the dominant reaction product of radiolytic surface modification processes on Europa. In recent compositional investigations employing linear mixture modeling, Dalton et al. (LPSC XV, #2511, 2009) and Shirley et al. (Icarus, in press, 2010) document a well-defined gradient of hydrated sulfuric acid abundance for a study area spanning the leading side - trailing side boundary in Argadnel Regio. Sulfuric acid hydrate abundance in this region increases toward the trailing side apex. Here we compare the derived sulfuric acid hydrate abundances at 41 locations on Europa's surface with independent model results describing 1) the sulfur ion flux (Hendrix et al., 2010, in preparation), and 2) the energetic electron flux, at the same locations. We improve upon the prior calculation of electron energy into the surface of Paranicas et al. (2009, in Europa, U. Arizona, p529; Pappalardo, McKinnon, & Khurana eds.) by incorporating a realistic pitch angle dependence of the distribution. While the sulfur ion implantation and electron energy deposition model distributions differ in important details, both show trailing side gradients similar to that found for the sulfuric acid hydrate. Correlation coefficients exceed 0.9 in comparisons of each of these models with the sulfuric acid hydrate distribution. Our results support models in which the electron energy flux drives reactions that utilize implanted sulfur to produce sulfuric acid hydrate. This work was performed at the California Institute of Technology-Jet Propulsion

  16. Sulfuric acid leaching kinetics of South African chromite

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Liu, Cheng-jun; Shi, Pei-yang; Zhang, Bo; Jiang, Mao-fa; Zhang, Qing-song; Zevenhoven, Ron; Saxén, Henrik

    2015-03-01

    The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching conditions. The dimensionless change in specific surface area and the conversion rate of the chromite were observed to exhibit a proportional relationship. A modified shrinking particle model was developed to account for the change in reactive surface area, and the model was fitted to experimental data. The resulting model was observed to describe experimental findings very well. Kinetics analysis revealed that the leaching process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ·mol-1.

  17. 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)

  18. Health effects of air pollutants: Sulfuric acid, the old and the new

    SciTech Connect

    Amdur, M.O. )

    1989-05-01

    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. 31 references.

  19. Infrared studies of sulfuric acid and its impact on polar and global ozone

    NASA Astrophysics Data System (ADS)

    Iraci, Laura Tracy

    Sulfuric acid aerosols are present throughout the lower stratosphere and play an important role in both polar and global ozone depletion. In the polar regions, stratospheric sulfate aerosols (SSAs) act as nuclei for the growth of polar stratospheric clouds (PSCs). Heterogeneous reactions can occur on these PSCs, leading to chlorine activation and catalytic ozone destruction. This thesis addresses the issue of polar ozone depletion through laboratory studies which examine the nucleation of PSCs on sulfuric acid. In addition, chemistry which occurs directly on sulfate aerosols may impact ozone at midlatitudes, and studies describing one such reaction are presented as well. To study the growth of type I PSCs on sulfuric acid, thin H2SO4 films were exposed to water and nitric acid vapors at stratospheric temperatures. Fourier transform infrared spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films which condensed. Supercooled liquid sulfuric acid films showed uptake of HNO3 to form ternary solutions, followed by crystallization of nitric acid trihydrate (NAT). When crystalline sulfuric acid tetrahydrate (SAT) films were exposed to nitric acid and water, condensation of a supercooled HNO3/H2O layer was often observed. As predicted by theory, some of the SAT crystal then dissolved, creating a ternary H2SO4/HNO3/H2O solution. From this solution, NAT nearly always crystallized, halting the phase change of sulfuric acid. If a supercooled nitric acid layer did not condense on frozen sulfuric acid, crystalline NAT was not deposited from the gas phase when SNAT/leq41. At significantly higher supersaturations, NAT could be forced to condense on sulfuric acid, regardless of its phase. Calculations of the contact parameter from experimental data indicate that m<0.79 for NAT on SAT, predicting a significant barrier to nucleation of NAT from the gas phase. While PSCs can form only in the cold polar regions of the stratosphere, sulfuric

  20. Heterogeneous Chemistry of HO2NO2 on Liquid Sulfuric Acid

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    1995-01-01

    The interaction of HO2NO2 (peroxynitric acid, PNA) vapor with liquid sulfuric acid surfaces was investigated for the acid contents ranging from 50 to 70 wt % and over a temperature range from 205 to 230 K, using a fast flow-reactor coupled to a chemical ionization mass spectrometer. PNA was observed to be physically taken up by liquid sulfuric acid, without undergoing irreversible aqueous phase reactions.

  1. Tungstate sulfuric acid (TSA)/KMnO4 as a novel heterogeneous system for rapid deoximation.

    PubMed

    Karami, Bahador; Montazerozohori, Morteza

    2006-09-28

    Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA), a new dibasic inorganic solid acid in which two sulfuric acid molecules connect to a tungstate moiety via a covalent bond. A variety of oximes were oxidized to their parent carbonyl compounds under mild conditions with excellent yields in short times by a heterogeneous wet TSA/KMnO4 in dichloromethane system.

  2. Relative Order of Sulfuric Acid, Bisulfate, Hydronium, and Cations at the Air-Water Interface.

    PubMed

    Hua, Wei; Verreault, Dominique; Allen, Heather C

    2015-11-04

    Sulfuric acid (H2SO4), bisulfate (HSO4(-)), and sulfate (SO4(2-)) are among the most abundant species in tropospheric and stratospheric aerosols due to high levels of atmospheric SO2 emitted from biomass burning and volcanic eruptions. The air/aqueous interfaces of sulfuric acid and bisulfate solutions play key roles in heterogeneous reactions, acid rain, radiative balance, and polar stratospheric cloud nucleation. Molecular-level knowledge about the interfacial distribution of these inorganic species and their perturbation of water organization facilitates a better understanding of the reactivity and growth of atmospheric aerosols and of the aerosol surface charge, thus shedding light on topics of air pollution, climate change, and thundercloud electrification. Here, the air/aqueous interface of NaHSO4, NH4HSO4, and Mg(HSO4)2 salt solutions as well as H2SO4 and HCl acid solutions are investigated by means of vibrational sum frequency generation (VSFG) and heterodyne-detected (HD) VSFG spectroscopy. VSFG spectra of all acid solutions show higher SFG response in the OH-bonded region relative to neat water, with 1.1 M H2SO4 being more enhanced than 1.1 M HCl. In addition, VSFG spectra of bisulfate salt solutions highly resemble that of the dilute H2SO4 solution (0.26 M) at a comparable pH. HD-VSFG (Im χ((2))) spectra of acid and bisulfate salt solutions further reveal that hydrogen-bonded water molecules are oriented preferentially toward the bulk liquid phase. General agreement between Im χ((2)) spectra of 1.1 M H2SO4 and 1.1 M HCl acid solutions indicate that HSO4(-) ions have a similar surface preference as that of chloride (Cl(-)) ions. By comparing the direction and magnitude of the electric fields arising from the interfacial ion distributions and the concentration of each species, the most reasonable relative surface preference that can be deduced from a simplified model follows the order H3O(+) > HSO4(-) > Na(+), NH4(+), Mg(2+) > SO4(2-). Interestingly

  3. 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.

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

    PubMed

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

    2016-10-20

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

  5. 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.

  6. 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.

  7. [Investigation on formation mechanism of secologanic acid sulfonates in sulfur-fumigated buds of Lonicera japonica].

    PubMed

    Guo, Ai-Li; Gao, Hui-Min; Chen, Liang-Mian; Zhang, Qi-Wei; Wang, Zhi-Min

    2014-05-01

    To investigate formation mechanism of secologanic acid sulfonates in sulfur-fumigated buds of Lonicera japonica, secologanic acid was enriched and purified from the sun-dried buds of L. japonica by various column chromatography on macroporus resin HPD-100, silica gel and ODS. The stimulation experiments of sulfur-fumigation process were carried out using secologanic acid reacted with SO2 in the aqueous solution. The reaction mechanism could be involved in the esterification or addition reaction. The present investigation provides substantial evidences for interpreting formation pathway of secologanic acid sulfonates in sulfur-fumigated buds of L. japonica.

  8. Synergistic cosolubilization of omega-3 fatty acid esters and CoQ10 in dilutable microemulsions.

    PubMed

    Deutch-Kolevzon, Rivka; Aserin, Abraham; Garti, Nissim

    2011-10-01

    Water-dilutable microemulsions were prepared and loaded with two types of omega-3 fatty acid esters (omega-3 ethyl esters, OEE; and omega-3 triacylglycerides, OTG), each separately and together with ubiquinone (CoQ(10)). The microemulsions showed high and synergistic loading capabilities. The linear fatty acid ester (OEE) solubilization capacity was greater than that of the bulky and robust OTG. The location of the guest molecules within the microemulsions at any dilution point were determined by electrical conductivity, viscosity, DSC, SAXS, cryo-TEM, SD-NMR, and DLS. We found that OEE molecules pack well within the surfactant tails to form reverse micelles that gradually, upon water dilution, invert into bicontinuous phase and finally into O/W droplets. The CoQ(10) increases the stabilization and solubilization of the omega-3 fatty acid esters because it functions as a kosmotropic agent in the micellar system. The hydrophobic and bulky OTG molecule strongly interferes with the tail packing and spaces them significantly - mainly in the low and medium range water dilutions. When added to the micellar system, CoQ(10) forms some reverse hexagonal mesophases. The inversion into direct micelles is more difficult in comparison to the OEE system and requires additional water dilution. The OTG with or without CoQ(10) destabilizes the structures and decreases the solubilization capacity since it acts as a chaotropic agent to the micellar system and as a kosmotropic agent to hexagonal packing. These results explain the differences in the behavior of these molecules with vehicles that solubilize them in aqueous phases. Temperature disorders the bicontinuous structures and reduces the supersaturation of the system containing OEE with CoQ(10); as a result CoQ(10) crystallization is retarded.

  9. Benefits of the stirred, autorefrigerated reactor in sulfuric acid alkylation

    SciTech Connect

    Ackerman, S.; Lerner, H.; Zaczepinski, S.

    1996-12-01

    Alkylation is a process which combines propylenes, butylenes, and pentylenes with isobutane in the presence of an acid catalyst (H{sub 2}SO{sub 4} or HF) to produce a premium quality gasoline blendstock. The alkylation process was developed in the late 1930`s and processing capacity grew tremendously during World War II in response to demand for aviation gasoline. Since that time, alkylation capacity has steadily grown to supply an important motor gasoline component. Now, more than 50 years later, alkylation is in the spotlight again for reformulated gasoline. Alkylate is a high octane, low sensitivity, low RVP, totally paraffinic material which represents the ideal blendstock for modern gasoline manufacture. Two types of modern reactor systems are currently offered for license to the refining industry for sulfuric acid alkylation. These are the stirred, autorefrigerated system offered by Exxon Research and Engineering (ERE) and the indirect, or effluent refrigerated system offered by others. By means of a case study example, this paper discusses the autorefrigerated reaction system and its benefits.

  10. Laboratory studies of 2H evaporator scale dissolution in dilute nitric acid

    SciTech Connect

    Oji, L.

    2014-09-23

    The rate of 2H evaporator scale solids dissolution in dilute nitric acid has been experimentally evaluated under laboratory conditions in the SRNL shielded cells. The 2H scale sample used for the dissolution study came from the bottom of the evaporator cone section and the wall section of the evaporator cone. The accumulation rate of aluminum and silicon, assumed to be the two principal elemental constituents of the 2H evaporator scale aluminosilicate mineral, were monitored in solution. Aluminum and silicon concentration changes, with heating time at a constant oven temperature of 90 deg C, were used to ascertain the extent of dissolution of the 2H evaporator scale mineral. The 2H evaporator scale solids, assumed to be composed of mostly aluminosilicate mineral, readily dissolves in 1.5 and 1.25 M dilute nitric acid solutions yielding principal elemental components of aluminum and silicon in solution. The 2H scale dissolution rate constant, based on aluminum accumulation in 1.5 and 1.25 M dilute nitric acid solution are, respectively, 9.21E-04 ± 6.39E-04 min{sup -1} and 1.07E-03 ± 7.51E-05 min{sup -1}. Silicon accumulation rate in solution does track the aluminum accumulation profile during the first few minutes of scale dissolution. It however diverges towards the end of the scale dissolution. This divergence therefore means the aluminum-to-silicon ratio in the first phase of the scale dissolution (non-steady state conditions) is different from the ratio towards the end of the scale dissolution. Possible causes of this change in silicon accumulation in solution as the scale dissolution progresses may include silicon precipitation from solution or the 2H evaporator scale is a heterogeneous mixture of aluminosilicate minerals with several impurities. The average half-life for the decomposition of the 2H evaporator scale mineral in 1.5 M nitric acid is 12.5 hours, while the half-life for the decomposition of the 2H evaporator scale in 1.25 M nitric acid is 10

  11. Strong Hydrogen Bonded Molecular Interactions between Atmospheric Diamines and Sulfuric Acid.

    PubMed

    Elm, Jonas; Jen, Coty N; Kurtén, Theo; Vehkamäki, Hanna

    2016-05-26

    We investigate the molecular interaction between methyl-substituted N,N,N',N'-ethylenediamines, propane-1,3-diamine, butane-1,4-diamine, and sulfuric acid using computational methods. Molecular structure of the diamines and their dimer clusters with sulfuric acid is studied using three density functional theory methods (PW91, M06-2X, and ωB97X-D) with the 6-31++G(d,p) basis set. A high level explicitly correlated CCSD(T)-F12a/VDZ-F12 method is used to obtain accurate binding energies. The reaction Gibbs free energies are evaluated and compared with values for reactions involving ammonia and atmospherically relevant monoamines (methylamine, dimethylamine, and trimethylamine). We find that the complex formation between sulfuric acid and the studied diamines provides similar or more favorable reaction free energies than dimethylamine. Diamines that contain one or more secondary amino groups are found to stabilize sulfuric acid complexes more efficiently. Elongating the carbon backbone from ethylenediamine to propane-1,3-diamine or butane-1,4-diamine further stabilizes the complex formation with sulfuric acid by up to 4.3 kcal/mol. Dimethyl-substituted butane-1,4-diamine yields a staggering formation free energy of -19.1 kcal/mol for the clustering with sulfuric acid, indicating that such diamines could potentially be a key species in the initial step in the formation of new particles. For studying larger clusters consisting of a diamine molecule with up to four sulfuric acid molecules, we benchmark and utilize a domain local pair natural orbital coupled cluster (DLPNO-CCSD(T)) method. We find that a single diamine is capable of efficiently stabilizing sulfuric acid clusters with up to four acid molecules, whereas monoamines such as dimethylamine are capable of stabilizing at most 2-3 sulfuric acid molecules.

  12. Pt/TiO2 (Rutile) Catalysts for Sulfuric Acid Decomposition in Sulfur-Based Thermochemical Water-Splitting Cycles

    SciTech Connect

    L. M. Petkovic; D. M. Ginosar; H. W. Rollins; K. C. Burch; P. J. Pinhero; H. H. Farrell

    2008-04-01

    Thermochemical cycles consist of a series of chemical reactions to produce hydrogen from water at lower temperatures than by direct thermal decomposition. All the sulfur-based cycles for water splitting employ the sulfuric acid decomposition reaction. This work reports the studies performed on platinum supported on titania (rutile) catalysts to investigate the causes of catalyst deactivation under sulfuric acid decomposition reaction conditions. Samples of 1 wt% Pt/TiO2 (rutile) catalysts were submitted to flowing concentrated sulfuric acid at 1123 K and atmospheric pressure for different times on stream (TOS) between 0 and 548 h. Post-operation analyses of the spent catalyst samples showed that Pt oxidation and sintering occurred under reaction conditions and some Pt was lost by volatilization. Pt loss rate was higher at initial times but total loss appeared to be independent of the gaseous environment. Catalyst activity showed an initial decrease that lasted for about 66 h, followed by a slight recovery of activity between 66 and 102 h TOS, and a period of slower deactivation after 102 h TOS. Catalyst sulfation did not seem to be detrimental to catalyst activity and the activity profile suggested that a complex dynamical situation involving platinum sintering, volatilization, and oxidation, along with TiO2 morphological changes affected catalyst activity in a non-monotonic way.

  13. Pretreatment of corn stover for sugar production using dilute hydrochloric acid followed by lime.

    PubMed

    Zu, Shuai; Li, Wen-zhi; Zhang, Mingjian; Li, Zihong; Wang, Ziyu; Jameel, Hasan; Chang, Hou-min

    2014-01-01

    In this study, a two stage process was evaluated to increase the sugar recovery. Firstly, corn stover was treated with diluted hydrochloric acid to maximize the xylose yield, and then the residue was treated with lime to alter the lignin structure and swell the cellulose surface. The optimal condition was 120 °C and 40 min for diluted hydrochloric acid pretreatment followed by lime pretreatment at 60 °C for 12h with lime loading at 0.1 g/g of substrate. The glucose and xylose yield was 78.0% and 97.0%, respectively, with cellulase dosage at 5 FPU/g of substrate. The total glucose yield increased to 85.9% when the cellulase loading was increased to 10 FPU/g of substrate. This two stage process was effective due to the swelling of the internal surface, an increase in the porosity and a decrease in the degree of polymerization.

  14. 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. , Albuquerque, NM )

    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.

  15. 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 ...

  16. Amine Reactivity with Nanoclusters of Sulfuric Acid and Ammonia

    NASA Astrophysics Data System (ADS)

    Johnston, M. V.; Bzdek, B. R.; DePalma, J.

    2011-12-01

    Alkyl amines have emerged as key species in new particle formation and growth. This interest is reinforced by ambient measurements of amines (e.g. Smith et al., 2010) and enhanced levels of nitrogen (e.g. Bzdek et al., 2011) during growth of newly formed particles. An important mechanism of amine uptake is aminium salt formation, either by substituting for ammonium ions that already exist in the particle or by opening new channels for salt formation that are not favorable with ammonia. This presentation will focus on recent experimental and computational work in our group to study amine uptake into charged nanoclusters of sulfuric acid and ammonia. In the experimental work, clusters are produced by electrospray of an ammonium sulfate solution and then drawn into a Fourier transform ion cyclotron resonance mass spectrometer where a specific cluster is isolated and exposed to amine vapor. We find that amine reactivity is dependent on the size, composition and charge of the isolated cluster. For small clusters of either polarity, all ammonium ions reside on the surface and amine substitution occurs with near unit reaction probability. As the cluster size increases, an ammonium ion can be encapsulated in the center of the cluster, which provides a steric hindrance to amine substitution. Negatively charged clusters are more likely to be acidic than positively charged clusters. For acidic clusters, incoming amine molecules first substitute for preexisting ammonium ions and then add to the cluster until a "neutralized" aminium bisulfate composition is reached. Computational studies of these clusters provide fundamental insight into the thermodynamics and kinetics of amine uptake.

  17. 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

  18. Mechanisms of volatile production from non-sulfur amino acids by irradiation

    NASA Astrophysics Data System (ADS)

    Ahn, Dong Uk; Lee, Eun Joo; Feng, Xi; Zhang, Wangang; Lee, Ji Hwan; Jo, Cheorun; Nam, Kichang

    2016-02-01

    Non-sulfur amino acid monomers were used to study the mechanisms of volatile production in meat by irradiation. Irradiation not only produced many volatiles but also increased the amounts of volatiles from non-sulfur amino acid monomers. The major reaction mechanisms involved in volatile production from each group of the amino acids by irradiation differ significantly. However, we speculate that the radiolysis of amino acid side chains were the major mechanism. In addition, Strecker degradation, especially the production of aldehydes from aliphatic group amino acids, and deamination, isomerization, decarboxylation, cyclic reaction and dehydrogenation of the initial radiolytic products were also contributed to the production of volatile compounds. Each amino acid monomers produced different odor characteristics, but the intensities of odor from all non-sulfur amino acid groups were very weak. This indicated that the contribution of volatiles produced from non-sulfur amino acids was minor. If the volatile compounds from non-sulfur amino acids, especially aldehydes, interact with other volatiles compounds such as sulfur compounds, however, they can contribute to the off-odor of irradiated meat significantly.

  19. Sulfuric acid-methanol electrolytes as an alternative to sulfuric-hydrofluoric acid mixtures for electropolishing of niobium

    SciTech Connect

    Zhao, Xin; Corcoran, Sean G.; Kelley, Michael J.

    2011-06-01

    Attainment of the greatest possible interior surface smoothness is critical to meeting the performance demands placed upon niobium superconducting radiofrequency (SRF) accelerator cavities by next generation projects. Electropolishing with HF-H{sub 2}SO{sub 4} electrolytes yields cavities that meet SRF performance goals, but a less-hazardous, more environmentally-friendly process is desirable. Reported studies of EP on chemically-similar tantalum describe the use of sulfuric acid-methanol electrolytes as an HF-free alternative. Reported here are the results of experiments on niobium samples with this electrolyte. Voltammetry experiments indicate a current plateau whose voltage range expands with increasing acid concentration and decreasing temperature. Impedance spectroscopy indicates that a compact salt film is responsible for the current plateau. Equivalent findings in electropolishing chemically-similar tantalum with this electrolyte were interpreted due to as mass transfer limitation by diffusion of Ta ions away from the anode surface. We infer that a similar mechanism is at work here. Conditions were found that yield leveling and brightening comparable to that obtained with HF-H{sub 2}SO{sub 4} mixtures.

  20. 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.

  1. Conversion of olive tree biomass into fermentable sugars by dilute acid pretreatment and enzymatic saccharification.

    PubMed

    Cara, Cristóbal; Ruiz, Encarnación; Oliva, José Miguel; Sáez, Felicia; Castro, Eulogio

    2008-04-01

    The production of fermentable sugars from olive tree biomass was studied by dilute acid pretreatment and further saccharification of the pretreated solid residues. Pretreatment was performed at 0.2%, 0.6%, 1.0% and 1.4% (w/w) sulphuric acid concentrations while temperature was in the range 170-210 degrees C. Attention is paid to sugar recovery both in the liquid fraction issued from pretreatment (prehydrolysate) and that in the water-insoluble solid (WIS). As a maximum, 83% of hemicellulosic sugars in the raw material were recovered in the prehydrolysate obtained at 170 degrees C, 1% sulphuric acid concentration, but the enzyme accessibility of the corresponding pretreated solid was not very high. In turn, the maximum enzymatic hydrolysis yield (76.5%) was attained from a pretreated solid (at 210 degrees C, 1.4% acid concentration) in which cellulose solubilization was detected; moreover, sugar recovery in the prehydrolysate was the poorest one among all the experiments performed. To take account of fermentable sugars generated by pretreatment and the glucose released by enzymatic hydrolysis, an overall sugar yield was calculated. The maximum value (36.3 g sugar/100 g raw material) was obtained when pretreating olive tree biomass at 180 degrees C and 1% sulphuric acid concentration, representing 75% of all sugars in the raw material. Dilute acid pretreatment improves results compared to water pretreatment.

  2. Measurement of cardiac output in adult and newborn animals by ascorbic acid dilution.

    PubMed

    Smallwood, J K; Haselby, K A; Paradise, R R

    1984-05-01

    We have developed an ascorbic acid-dilution method for measuring cardiac output which requires minimal blood withdrawal. Ascorbate is injected into a central venous catheter. The indicator-dilution curve is obtained by drawing blood from an arterial catheter through an amperometric cell at 0.96 ml/min for 35 s. The current is measured by a picoammeter . A calibration curve is obtained in 15 s prior to each indicator-dilution curve. An on-line digital computer measures the curve areas and calculates the cardiac output. Cardiac outputs of heparinized dogs anesthetized with pentobarbital and halothane measured by this method (AA) compared closely to cardiac outputs measured by the dye-dilution method (CG) (AA = 0.96 CG + 20 ml/min, r = 0.98). Both the cardiac output and the arterial blood pressure remained stable during replicate measurements of the cardiac output of 1-day-old piglets. This system allows cardiac output determinations of neonatal subjects without excessive blood removal and, with further development, should be practical in human neonates.

  3. Evaluation of oxygen pressurized microwave-assisted digestion of botanical materials using diluted nitric acid.

    PubMed

    Bizzi, Cezar Augusto; Barin, Juliano Smanioto; Müller, Edson Irineu; Schmidt, Lucas; Nóbrega, Joaquim A; Flores, Erico Marlon Moraes

    2011-02-15

    The feasibility of diluted nitric acid solutions for microwave-assisted decomposition of botanical samples in closed vessels was evaluated. Oxygen pressurized atmosphere was used to improve the digestion efficiency and Al, Ca, K, Fe, Mg and Na were determined in digests by inductively coupled plasma optical emission spectrometry (ICP OES). Efficiency of digestion was evaluated taking into account the residual carbon content (RCC) and residual acidity in digests. Samples were digested using nitric acid solutions (2, 3, 7, and 14 mol L(-1) HNO(3)) and the effect of gas phase composition inside the reaction vessels by purging the vessel with Ar (inert atmosphere, 1 bar), air (20% of oxygen, 1 bar) and pure O(2) (100% of oxygen, 1 bar) was evaluated. The influence of oxygen pressure was studied using pressures of 5, 10, 15 and 20 bar. It was demonstrated that a diluted nitric acid solution as low as 3 mol L(-1) was suitable for an efficient digestion of sample masses up to 500 mg of botanical samples using 5 bar of oxygen pressure. The residual acidities in final digests were lower than 45% in relation to the initial amount of acid used for digestion (equivalent to 1.3 mol L(-1) HNO(3)). The accuracy of the proposed procedure was evaluated using certified reference materials of olive leaves, apple leaves, peach leaves and pine needles. Using the optimized conditions for sample digestion, the results obtained were in agreement with certified values. The limit of quantification was improved up to a factor of 14.5 times for the analytes evaluated. In addition, the proposed procedure was in agreement with the recommendations of the green chemistry once it was possible to obtain relatively high digestion efficiency (RCC<5%) using only diluted HNO(3), which is important to minimize the generation of laboratory residues.

  4. Optimization of wastewater microalgae saccharification using dilute acid hydrolysis for acetone, butanol, and ethanol fermentation

    SciTech Connect

    Castro, Yessica; Ellis, Joshua T.; Miller, Charles D.; Sims, Ronald C.

    2015-02-01

    Exploring and developing sustainable and efficient technologies for biofuel production are crucial for averting global consequences associated with fuel shortages and climate change. Optimization of sugar liberation from wastewater algae through acid hydrolysis was determined for subsequent fermentation to acetone, butanol, and ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. Acid concentration, retention time, and temperature were evaluated to determine optimal hydrolysis conditions by assessing the sugar and ABE yield as well as the associated costs. Sulfuric acid concentrations ranging from 0-1.5 M, retention times of 40-120 min, and temperatures from 23°C- 90°C were combined to form a full factorial experiment. Acid hydrolysis pretreatment of 10% dried wastewater microalgae using 1.0 M sulfuric acid for 120 min at 80-90°C was found to be the optimal parameters, with a sugar yield of 166.1 g for kg of dry algae, concentrations of 5.23 g/L of total ABE, and 3.74 g/L of butanol at a rate of USD $12.83 per kg of butanol.

  5. Theoretical study of ultraviolet induced photodissociation dynamics of sulfuric acid

    NASA Astrophysics Data System (ADS)

    Murakami, Tatsuhiro; Ohta, Ayumi; Suzuki, Tomoya; Ikeda, Kumiko; Danielache, Sebastian O.; Nanbu, Shinkoh

    2015-05-01

    Photodissociation dynamics of sulfuric acid after excitation to the first and second excited states (S1 and S2) were studied by an on-the-fly ab initio molecular dynamics simulations based on the Zhu-Nakamura version of the trajectory surface hopping (ZN-TSH). Forces acting on the nuclear motion were computed on-the-fly by CASSCF method with Dunning's augmented cc-pVDZ basis set. It was newly found that the parent molecule dissociated into two reaction-channels (i) HSO4(12A″) + H(2S) by S1-excitation, and (ii) HSO4(22A″) + H(2S) by S2-excitation. The direct dissociation dynamics yield products different from the SO2 + 2OH fragments often presented in the literature. Both channels result in the same product and differs only in the electronic state of the HSO4 fragment. The trajectories running on S2 do not hop with S0 and a nonadiabatic transition happens at the S2-S1 conical intersection located at a longer OH bond-length than the S1-S0 intersection producing an electronic excited state (22A″) of HSO4 product.

  6. Temperature and intensity of sonoluminescence radiation in sulfuric acid.

    PubMed

    Moshaii, A; Hoseini, M A; Gharibzadeh, S; Tavakoli-Anaraki, A

    2012-07-01

    The spectral radiation of sonoluminescence (SL) from sulfuric acid doped with various Xe concentrations has been studied in a hydrochemical simulation, including radiation effects of both continuum and line emissions. The simulation considers the same temperature for both continuum and line parts of the SL spectrum and gives results in agreement with the experiment. Also, it can properly show period-doubling dynamics for a 50 torr bubble. For most of the allowable driving pressures, it is shown that both the temperature and the intensity of SL for a 4 torr bubble are greater than those of a 50 torr bubble. However, for the range of pressures near the maximum driving conditions of the 50 torr bubble, the SL intensity of this bubble can be up to three orders of magnitude greater than the 4 torr bubble. This case, which is in agreement with the experiment, is obtained when the light-emitting region of the 50 torr bubble is about three orders of magnitude greater than the 4 torr bubble.

  7. 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.

  8. Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

    NASA Astrophysics Data System (ADS)

    Mohammadabad, Farhad Khorramshahi; Hejazi, Sina; khaki, Jalil Vahdati; Babakhani, Abolfazl

    2016-04-01

    This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching (mechanochemical leaching) of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to determine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide (H2O2) and ferric sulfate (Fe2(SO4)3) after 20 h of mechanochemical leaching reached 28% and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.

  9. Preparation of levoglucosenone through sulfuric acid promoted pyrolysis of bagasse at low temperature.

    PubMed

    Sui, Xian-wei; Wang, Zhi; Liao, Bing; Zhang, Ying; Guo, Qing-xiang

    2012-01-01

    Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350 °C and sulfuric acid loadings from 0.92 to 7.10 wt.%. An optimal LGO yield of 7.58 wt.% was obtained at 270 °C with a sulfuric acid pretreatment concentration of 0.05 M (corresponding to 4.28 wt.% sulfuric acid loading). For comparison, microcrystalline cellulose pretreated by 0.05 M sulfuric acid solution was pyrolyzed at temperature from 270 °C to 320 °C, and bagasse loaded with 3-5 wt.% phosphoric acid was pyrolyzed at temperature from 270 °C to 350 °C. The highest yield of LGO from bagasse was 30% higher than that from microcrystalline cellulose, and treatment with sulfuric acid allowed a 21% higher yield than treatment with phosphoric acid.

  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

  11. Optimization of High Solids Dilute Acid Hydrolysis of Spent Coffee Ground at Mild Temperature for Enzymatic Saccharification and Microbial Oil Fermentation.

    PubMed

    Wang, Hui-Min David; Cheng, Yu-Shen; Huang, Chi-Hao; Huang, Chia-Wei

    2016-10-01

    Soluble coffee, being one of the world's most popular consuming drinks, produces a considerable amount of spent coffee ground (SCG) along with its production. The SCG could function as a potential lignocellulosic feedstock for production of bioproducts. The objective of this study is to investigate the possible optimal condition of dilute acid hydrolysis (DAH) at high solids and mild temperature condition to release the reducing sugars from SCG. The optimal condition was found to be 5.3 % (w/w) sulfuric acid concentration and 118 min reaction time. Under the optimal condition, the mean yield of reducing sugars from enzymatic saccharification of defatted SCG acid hydrolysate was 563 mg/g. The SCG hydrolysate was then successfully applied to culture Lipomyces starkeyi for microbial oil fermentation without showing any inhibition. The results suggested that dilute acid hydrolysis followed by enzymatic saccharification has the great potential to convert SCG carbohydrates to reducing sugars. This study is useful for the further developing of biorefinery using SCG as feedstock at a large scale.

  12. Effect of amino acid intake on brush-border membrane uptake of sulfur amino acids.

    PubMed

    Chesney, R W; Gusowski, N; Padilla, M; Lippincott, S

    1986-07-01

    Alterations in the intake of sulfur amino acids (SAA) changes the rat renal brush-border membrane uptake of the beta-amino acid, taurine. A low-SAA diet enhances and a high-taurine diet reduces uptake (Chesney et al., Kidney Int. 24: 588-594, 1983). Neither the low-SAA diet nor the high-taurine diet alters the time course or concentration-dependent accumulation of the sulfur amino acids methionine and cystine or of inorganic sulfate. By contrast the uptake of beta-alanine, another beta-amino acid that competes with taurine, is greater in animals on the low-SAA diet. The high-taurine diet does not change beta-alanine uptake. The plasma levels of taurine are altered by dietary change, but not the values for methionine and cystine. This study indicates that renal adaptation is expressed for beta-alanine, a nonsulfur-containing beta-amino acid. By contrast, methionine, cystine, and sulfate, which participate in a variety of synthetic and conjugative processes, are not conserved by the renal brush-border surface following ingestion of either a low-methionine and -cystine diet or high-taurine diet.

  13. Reaction of isoprene on thin sulfuric acid films: kinetics, uptake, and product analysis.

    PubMed

    Connelly, Brandon M; Tolbert, Margaret A

    2010-06-15

    A high vacuum Knudsen flow reactor was used to determine the reactive uptake coefficient, gamma, of isoprene on sulfuric acid films as a function of sulfuric acid weight percent, temperature, and relative humidity. No discernible dependence was observed for gamma over the range of temperatures (220 - 265 K) and pressures (10(-7) Torr -10(-4) Torr) studied. However, the uptake coefficient increased with increased sulfuric acid concentration between the range of 78 wt % (gamma(i) approximately 10(-4)) and 93 wt % (gamma(i) approximately 10(-3)). In addition to the Knudsen Cell, a bulk study was conducted between 60 and 85 wt % H(2)SO(4) to quantify uptake at lower acid concentrations and to determine reaction products. After exposing sulfuric acid to gaseous isoprene the condensed phase products were extracted and analyzed using gas chromatography/mass spectrometry (GC/MS). Isoprene was observed to polymerize in the sulfuric acid and form yellow/red colored monoterpenes and cyclic sesquiterpenes. Finally, addition of water to the 85 wt % sulfuric acid/isoprene product mixture released these terpenes from the condensed phase into the gas phase. Together these experiments imply that direct isoprene uptake will not produce significant SOA; however, terpene production from the small uptake may be relevant for ultrafine particles and could affect growth and nucleation.

  14. Cytotoxicity of sulfurous acid on cell membrane and bioactivity of Nitrosomonas europaea.

    PubMed

    Jiang, Ruiyu; Wang, Mingqing; Xue, Jianliang; Xu, Ning; Hou, Guihua; Zhang, Wubing

    2015-01-01

    Nitrosomonas europaea, an ammonia oxidizing bacterium, was chosen as a research model to study the alteration of cell membrane in the presence of sulfurous acid and biodegradation of acetochlor. Significant changes of the outer cell membrane were observed in the presence of sulfurous acid using scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM). The fluorescence polarization has shown a significant decrease in membrane fluidity and the increase of permeability of cell membrane. Lysozyme experiment show the cell becomes easily influenced by substance in medium. Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) measurements show considerable amount of Ca(2+) and Mg(2+) in the supernatant from the sulfurous acid exposed cells. Sulfurous acid treatment enhanced the ability of N. europaea to degrade acetochlor. On this basis, it can be concluded that the increased cell permeability is favor for the absorbability of nutrition. As a result, N. europaea grows faster and the biodegradation efficiency was improved.

  15. Heterogeneous interactions of calcite aerosol with sulfur dioxide and sulfur dioxide-nitric acid mixtures.

    PubMed

    Prince, A Preszler; Kleiber, P; Grassian, V H; Young, M A

    2007-07-14

    The heterogeneous chemistry of sulfur dioxide with CaCO(3) (calcite) aerosol as a function of relative humidity (RH) has been studied under isolated particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reaction of SO(2) with calcite produced gas phase CO(2) as a product in addition to the conversion of the particulate carbonate to sulfite. The reaction extent was found to increase with elevated RH, as has been observed for the similar reaction with HNO(3), but much higher relative humidities were needed to significantly enhance the reaction. Mixed experiments in which calcite aerosol was exposed to both HNO(3) and SO(2) were also performed. The overall reaction extent at a given relative humidity did not appear to be increased by having both reactant gases present. The role of carbonate aerosol as an atmospheric sink for sulfur dioxide and particulate nitrogen and sulfur correlations are discussed.

  16. 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.

  17. Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

    1993-01-01

    A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

  18. Understanding the Effects of Dilute Sulfur Additions, and Metallization, on the Thermoelectric Properties of Pnictogen Chalcogenides and their Interfaces

    NASA Astrophysics Data System (ADS)

    Devender

    Realizing materials with high thermoelectric figure-of-merit ZT is an exacting challenge because it entails simultaneously obtaining a high Seebeck coefficient, a high electrical conductivity, and a low thermal conductivity, while these properties are usually unfavorably coupled. This thesis demonstrates multifold enhancements in the power factor in sulfur-doped binary and ternary pnictogen chalcogenide nanocrystals and assemblies, and describes the property enhancement mechanisms. The correlations between interfacial thermal and electronic transport, and interfacial diffusion and phase formation in metallized n- and p-type pnictogen chalcogenide structures are also revealed. We show that 400 ppm to 2 at.% sulfur doping can increase both Seebeck coefficient and electrical conductivity, while maintaining low thermal conductivity. Our results show that sulfur-induced property enhancements in Bi2Te 2Se are underpinned by increased density of states effective mass, unlike the mechanism of diminished bipolar charge carrier transport prevalent in sulfur-doped Bi2Te3. Exploiting such effects is anticipated to be attractive for realizing higher ZT nanomaterials. We also show that electrical contact conductivity in metallized pnictogen chalcogenide interfaces is sensitive to metal diffusion and telluride formation. In particular, Ni contacts yield the highest electrical contact conductivity and Cu the lowest, correlating with extent of metal diffusion and p-type metal-telluride formation. We finally show that pnictogen chalcogenides metallized with Sn-Ag-Cu/Ni solder-barrier bilayers exhibit ten-fold higher interfacial thermal conductance than that obtained with In/Ni bilayer metallization. Decreased interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher interfacial thermal conductance. Our findings should facilitate the design and development of pnictogen chalcogenide-based thermoelectric materials and devices.

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

    NASA Technical Reports Server (NTRS)

    Palmer, K. F.; Williams, D.

    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 determined for the visible, near infrared, and intermediate infrared wavelength regions.

  20. 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.

  1. Therapeutic paracetamol treatment in older persons induces dietary and metabolic modifications related to sulfur amino acids.

    PubMed

    Pujos-Guillot, Estelle; Pickering, Gisèle; Lyan, Bernard; Ducheix, Gilles; Brandolini-Bunlon, Marion; Glomot, Françoise; Dardevet, Dominique; Dubray, Claude; Papet, Isabelle

    2012-02-01

    Sulfur amino acids are determinant for the detoxification of paracetamol (N-acetyl-p-aminophenol) through sulfate and glutathione conjugations. Long-term paracetamol treatment is common in the elderly, despite a potential cysteine/glutathione deficiency. Detoxification could occur at the expense of anti-oxidative defenses and whole body protein stores in elderly. We tested how older persons satisfy the extra demand in sulfur amino acids induced by long-term paracetamol treatment, focusing on metabolic and nutritional aspects. Effects of 3 g/day paracetamol for 14 days on fasting blood glutathione, plasma amino acids and sulfate, urinary paracetamol metabolites, and urinary metabolomic were studied in independently living older persons (five women, five men, mean (±SEM) age 74 ± 1 years). Dietary intakes were recorded before and at the end of the treatment and ingested sulfur amino acids were evaluated. Fasting blood glutathione, plasma amino acids, and sulfate were unchanged. Urinary nitrogen excretion supported a preservation of whole body proteins, but large-scale urinary metabolomic analysis revealed an oxidation of some sulfur-containing compounds. Dietary protein intake was 13% higher at the end than before paracetamol treatment. Final sulfur amino acid intake reached 37 mg/kg/day. The increase in sulfur amino acid intake corresponded to half of the sulfur excreted in urinary paracetamol conjugates. In conclusion, older persons accommodated to long-term paracetamol treatment by increasing dietary protein intake without any mobilization of body proteins, but with decreased anti-oxidative defenses. The extra demand in sulfur amino acids led to a consumption far above the corresponding population-safe recommendation.

  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. Removal characteristics of sulfuric acid aerosols from coal-fired power plants.

    PubMed

    Pan, Danping; Yang, Linjun; Wu, Hao; Huang, Rongting

    2017-03-01

    With increasing attention on sulfuric acid emission, investigations on the removal characteristics of sulfuric acid aerosols by the limestone gypsum wet flue gas desulfurization (WFGD) system and the wet electrostatic precipitator (WESP) were carried out in two coal-fired power plants, and the effects of the WFGD scrubber type and the flue gas characteristics were discussed. The results showed that it was necessary to install the WESP device after desulfurization, as the WFGD system was inefficient to remove sulfuric acid aerosols from the flue gas. The removal efficiency of sulfuric acid aerosols in the WFGD system with double scrubbers ranged from 50% to 65%, which was higher than that with a single scrubber, ranging from 30% to 40%. Furthermore, the removal efficiency of WESP on the sulfuric acid aerosols was from 47.9% to 52.4%. With increased concentrations of SO3 and particles in the flue gas, the removal efficiencies of the WFGD and the WESP on the sulfuric acid aerosols were increased.

  4. 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.

  5. High titer gluconic acid fermentation by Aspergillus niger from dry dilute acid pretreated corn stover without detoxification.

    PubMed

    Zhang, Hongsen; Zhang, Jian; Bao, Jie

    2016-03-01

    This study reported a high titer gluconic acid fermentation using dry dilute acid pretreated corn stover (DDAP) hydrolysate without detoxification. The selected fermenting strain Aspergillus niger SIIM M276 was capable of inhibitor degradation thus no detoxification on pretreated corn stover was required. Parameters of gluconic acid fermentation in corn stover hydrolysate were optimized in flasks and in fermentors to achieve 76.67 g/L gluconic acid with overall yield of 94.91%. The sodium gluconate obtained from corn stover was used as additive for extending setting time of cement mortar and similar function was obtained with starch based sodium gluconate. This study provided the first high titer gluconic acid production from lignocellulosic feedstock with potential of industrial applications.

  6. Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1988-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  7. Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1989-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  8. Determination of the viscosity number of thermoplastics in dilute solution; polyamides (PA)

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This West German Standard presents a test used to determine the viscosity number of polyamides and copolyamides which are easily diluted in sulfuric acid, and for other polyamides which are less easily diluted in sulfuric acid, and which are diluted in m-cresol. As formic acid is often used in industry instead of sulfuric acid, this solvent is also presented as an alternative, however, sulfuric acid is preferred because of the thermodynamic solubility characteristics of the polyamides and the handling safety. In addition, it is shown which solvent should be used for each polyamide. Finally, determinations concerning the preparation of the samples are presented. Using the viscosity number, a determination of the molar mass of the polyamides is possible.

  9. ENERGY EFFICIENCY LIMITS FOR A RECUPERATIVE BAYONET SULFURIC ACID DECOMPOSITION REACTOR FOR SULFUR CYCLE THERMOCHEMICAL HYDROGEN PRODUCTION

    SciTech Connect

    Gorensek, M.; Edwards, T.

    2009-06-11

    A recuperative bayonet reactor design for the high-temperature sulfuric acid decomposition step in sulfur-based thermochemical hydrogen cycles was evaluated using pinch analysis in conjunction with statistical methods. The objective was to establish the minimum energy requirement. Taking hydrogen production via alkaline electrolysis with nuclear power as the benchmark, the acid decomposition step can consume no more than 450 kJ/mol SO{sub 2} for sulfur cycles to be competitive. The lowest value of the minimum heating target, 320.9 kJ/mol SO{sub 2}, was found at the highest pressure (90 bar) and peak process temperature (900 C) considered, and at a feed concentration of 42.5 mol% H{sub 2}SO{sub 4}. This should be low enough for a practical water-splitting process, even including the additional energy required to concentrate the acid feed. Lower temperatures consistently gave higher minimum heating targets. The lowest peak process temperature that could meet the 450-kJ/mol SO{sub 2} benchmark was 750 C. If the decomposition reactor were to be heated indirectly by an advanced gas-cooled reactor heat source (50 C temperature difference between primary and secondary coolants, 25 C minimum temperature difference between the secondary coolant and the process), then sulfur cycles using this concept could be competitive with alkaline electrolysis provided the primary heat source temperature is at least 825 C. The bayonet design will not be practical if the (primary heat source) reactor outlet temperature is below 825 C.

  10. 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.

  11. 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.

  12. Fermentation of dilute acid pretreated Populus by Clostridium thermocellum, Caldicellulosiruptor bescii, and Caldicellulosiruptor obsidiansis

    DOE PAGES

    Yee, Kelsey L.; Rodriguez, Jr., Miguel; Hamilton, Choo Yieng; ...

    2015-07-25

    Consolidated bioprocessing (CBP), which merges enzyme production, biomass hydrolysis, and fermentation into a single step, has the potential to become an efficient and economic strategy for the bioconversion of lignocellulosic feedstocks to transportation fuels or chemicals. In this study, we evaluated Clostridium thermocellum, Caldicellulosiruptor bescii, and Caldicellulosiruptor obsidiansis, three , thermophilic,cellulolytic, mixed-acid fermenting candidate CBP microorganisms, for their fermentation capabilities using dilute acid pretreated Populus as a model biomass feedstock. Under pH controlled, anaerobic fermentation conditions, each candidate successfully digested a minimum of 75% of the cellulose from dilute acid pretreated Populus, as indicated by an increase in planktonic cellsmore » and end-product metabolites and a concurrent decrease in glucan content. C. thermocellum, which employs a cellulosomal approach to biomass degradation, required 120 hours to achieve 75% cellulose utilization. In contrast, the non-cellulosomal, secreted hydrolytic enzyme system of the Caldicellulosiruptor sp. required 300 hours to achieve similar results. End-point fermentation conversions for C. thermocellum, C. bescii, and C. obsidiansis were determined to be 0.29, 0.34, and 0.38 grams of total metabolites per gram of loaded glucan, respectively. This data provide a starting point for future strain engineering efforts that can serve to improve the biomass fermentation capabilities of these three promising candidate CBP platforms.« less

  13. [Measurement of lead in high-salt food with sulfuric-nitric acid to treat food ash].

    PubMed

    Shi, Y; Zhang, Y; Wang, Y

    2001-03-01

    Lead in high-salt food was measured by treating the ash with sulfuric-nitric acid, and diluting lead standard with sodium sulfate to eliminate the disturbance of chloride in detecting lead with atomic absorption spectrophotometry. The minimum detection limit was 0.10 mg/kg. The relative standard deviation is 1.72%, 5.00% and 7.14% while the amount of lead was 8.70, 2.40 and 1.40 micrograms respectively. The recovery varied between 90.0%-109.0%. There was no significant difference (P > 0.05) of the lead content between the mentioned method and extraction flame photometry. The amount of lead is higher obviously than that of other two methods by eliminating the disturbance of chloride. The method was simple, precise and accurate, and suitable for hygienic examination.

  14. Determination of tenuazonic acid in human urine by means of a stable isotope dilution assay.

    PubMed

    Asam, Stefan; Habler, Katharina; Rychlik, Michael

    2013-05-01

    The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02-100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3-17.3 μg/L or 2.3-10.3 ng/mg(-1) creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54-81 % after 6 h, depending on matrix and volunteer. After 24 h, 87-93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.

  15. Atmospheric evolution of sulfur emissions from Kı̅lauea: real-time measurements of oxidation, dilution, and neutralization within a volcanic plume.

    PubMed

    Kroll, Jesse H; Cross, Eben S; Hunter, James F; Pai, Sidhant; Wallace, Lisa M M; Croteau, Philip L; Jayne, John T; Worsnop, Douglas R; Heald, Colette L; Murphy, Jennifer G; Frankel, Sheila L

    2015-04-07

    The high atmospheric concentrations of toxic gases, particulate matter, and acids in the areas immediately surrounding volcanoes can have negative impacts on human and ecological health. To better understand the atmospheric fate of volcanogenic emissions in the near field (in the first few hours after emission), we have carried out real-time measurements of key chemical components of the volcanic plume from Kı̅lauea on the Island of Hawai'i. Measurements were made at two locations, one ∼ 3 km north-northeast of the vent and the other 31 km to the southwest, with sampling at each site spanning a range of meteorological conditions and volcanic influence. Instrumentation included a sulfur dioxide monitor and an Aerosol Chemical Speciation Monitor, allowing for a measurement of the partitioning between the two major sulfur species (gas-phase SO2 and particulate sulfate) every 5 min. During trade wind conditions, which sent the plume toward the southwest site, sulfur partitioning exhibited a clear diurnal pattern, indicating photochemical oxidation of SO2 to sulfate; this enabled the quantitative determination of plume age (5 h) and instantaneous SO2 oxidation rate (2.4 × 10(-6) s(-1) at solar noon). Under stagnant conditions near the crater, the extent of SO2 oxidation was substantially higher, suggesting faster oxidation. The particles within the plume were extremely acidic, with pH values (controlled largely by ambient relative humidity) as low as -0.8 and strong acidity (controlled largely by absolute sulfate levels) up to 2200 nmol/m(3). The high variability of sulfur partitioning and particle composition underscores the chemically dynamic nature of volcanic plumes, which may have important implications for human and ecological health.

  16. Comparison of sulfuric and oxalic acid anodizing for preparation of thermal control coatings for spacecraft

    NASA Technical Reports Server (NTRS)

    Le, Huong G.; Watcher, John M.; Smith, Charles A.

    1988-01-01

    The development of thermal control surfaces, which maintain stable solar absorptivity and infrared emissivity over long periods, is challenging due to severe conditions in low-Earth orbit (LEO). Some candidate coatings are second-surface silver-coated Teflon; second-surface, silvered optical solar reflectors made of glass or quartz; and anodized aluminum. Sulfuric acid anodized and oxalic acid anodized aluminum was evaluated under simulated LEO conditions. Oxalic acid anodizing shows promise of greater stability in LEO over long missions, such as the 30 years planned for the Space Station. However, sulfuric acid anodizing shows lower solar absorptivity.

  17. First direct sulfuric acid detection in the exhaust plume of a jet aircraft in flight

    NASA Astrophysics Data System (ADS)

    Curtius, J.; Sierau, B.; Arnold, F.; Baumann, R.; Busen, R.; Schulte, P.; Schumann, U.

    Sulfuric acid (SA) was for the first time directly detected in the exhaust plume of a jet aircraft in flight. The measurements were made by a novel aircraft-based VACA (Volatile Aerosol Component Analyzer) instrument of MPI-K Heidelberg while the research aircraft Falcon was chasing another research aircraft ATTAS. The VACA measures the total SA in the gas and in volatile submicron aerosol particles. During the chase the engines of the ATTAS alternatively burned sulfur-poor and sulfur-rich fuel. In the sulfur-rich plume very marked enhancements of total SA were observed of up to 1300 pptv which were closely correlated with ΔCO2 and ΔT and were far above the local ambient atmospheric background-level of typically 15-50 pptv. Our observations indicate a lower limit for the efficiency ɛ for fuel-sulfur conversion to SA of 0.34 %.

  18. Reaction kinetics of waste sulfuric acid using H2O2 catalytic oxidation.

    PubMed

    Wang, Jiade; Hong, Binxun; Tong, Xinyang; Qiu, Shufeng

    2016-12-01

    The process of recovering waste sulfuric acids using H2O2 catalytic oxidation is studied in this paper. Activated carbon was used as catalyst. Main operating parameters, such as temperature, feed rate of H2O2, and catalyst dosage, have effects on the removal of impurities from waste sulfuric acids. The reaction kinetics of H2O2 catalytic oxidation on impurities are discussed. At a temperature of 90°C, H2O2 feeding rate of 50 g (kg waste acid)(-1) per hour, and catalyst dosage of 0.2 wt% (waste acid weight), the removal efficiencies of COD and chrominance were both more than 99%, the recovery ratio of sulfuric acid was more than 95%, and the utilization ratio of H2O2 was 88.57%.

  19. Efficient hydrogen generation from sodium borohydride hydrolysis using silica sulfuric acid catalyst

    NASA Astrophysics Data System (ADS)

    Manna, Joydev; Roy, Binayak; Sharma, Pratibha

    2015-02-01

    A heterogeneous acid catalyst, silica sulfuric acid, was prepared from silica gel (SiO2) and sulfuric acid (H2SO4). Addition of SO3H functional group to SiO2 has been confirmed through various characterization techniques. The effect of this heterogeneous acid catalyst on hydrogen generation from sodium borohydride hydrolysis reaction was studied for different ratios of catalyst to NaBH4 and at different temperatures. The catalyst exhibited high catalytic activity towards sodium borohydride hydrolysis reaction. The activation energy of the NaBH4 hydrolysis reaction in the presence of silica sulfuric acid was calculated to be the lowest (17 kJ mol-1) among reported heterogeneous catalysts till date.

  20. Observation of neutral sulfuric acid-amine containing clusters in laboratory and ambient measurements

    SciTech Connect

    Kuang C.; Zhao, J.; Smith, J. N.; Eisele, F. L.; Chen, M.; McMurry, P. H.

    2011-11-02

    Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a microscopic molecular scale (from molecular sizes up to 2 nm) have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfuric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to particle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectrometer designed for measuring neutral clusters formed in the atmosphere during nucleation. An experimental technique, which we refer to as Semi-Ambient Signal Amplification (SASA), was employed. Sulfuric acid was added to ambient air, and the concentrations and composition of clusters in this mixture were analyzed by the Cluster CIMS. This experimental approach led to significantly higher cluster concentrations than are normally found in ambient air, thereby increasing signal-to-noise levels and allowing us to study reactions between gas phase species in ambient air and sulfuric acid containing clusters. Mass peaks corresponding to clusters containing four H{sub 2}SO{sub 4} molecules and one amine molecule were clearly observed, with the most abundant sulfuric acid-amine clusters being those containing a C2- or C4-amine (i.e. amines with masses of 45 and 73 amu). Evidence for C3- and C5-amines (i.e. amines with masses of 59 and 87 amu) was also found, but their correlation with sulfuric acid tetramer was not as strong as was observed for the C2- and C4-amines. The formation mechanisms for those sulfuric acid

  1. Revealing the molecular structural transformation of hardwood and softwood in dilute acid flowthrough pretreatment

    DOE PAGES

    Zhang, Libing; Pu, Yunqiao; Univ. of Tennessee, Knoxville, TN; ...

    2016-10-03

    To understand better the intrinsic recalcitrance of lignocellulosic biomass, the main hurdle to its efficient deconstruction, the effects of dilute acid flowthrough pretreatment on the dissolution chemistry of hemicellulose, cellulose, and lignin for both hardwood (e.g., poplar wood) and softwood (e.g., lodgepole pine wood) were investigated at temperatures of 200 to 270 °C and a flow rate of 25 mL/min with 0.05% (w/w) H2SO4. Results suggested that the softwood cellulose was more readily degraded into monomeric sugars than that of hardwood under same pretreatment conditions. However, while the hardwood lignin was completely removed into hydrolysate, ~30% of the softwood ligninmore » remained as solid residues under identical conditions, which was plausibly caused by vigorous C5-active recondensation reactions (C–C5). As a result, effects of molecular structural features (i.e., lignin molecular weight, cellulose crystallinity, and condensed lignin structures) on the recalcitrance of hardwood and softwood to dilute acid pretreatment were identified for the first time in this study, providing important insights to establish the effective biomass pretreatment.« less

  2. Structural Transformation of Isolated Poplar and Switchgrass Lignins from Dilute Acid Pretreatment

    SciTech Connect

    Sun, Qining; Pu, Yunqiao; Meng, Xianzhi; Wells, Tyrone; Ragauskas, Arthur J.

    2015-08-27

    A key step in conversion of cellulosic biomass into sustainable fuels and chemicals is thermochemical pretreatment to reduce plant cell wall recalcitrance. Obtaining an improved understanding of the fundamental chemistry of lignin, the most recalcitrant component of biomass, during pretreatment is critical to the continued development of renewable biofuel production. To examine the intrinsic chemistry of lignin during dilute acid pretreatment (DAP), lignin was isolated from poplar and switchgrass using a cellulolytic enzyme system and then treated under DAP conditions. These results highlight that lignin is subjected to depolymerization reactions within the first 2 min of dilute acid pretreatment and these changes are accompanied by increased generation of aliphatic and phenolic hydroxyl groups of lignin. This is followed by a competing set of depolymerization and repolymerization reactions that lead to a decrease in the content of guaiacyl lignin units and an increase in condensed lignin units as the reaction residence time is extended beyond 5 min. Finally, we showed that a detailed comparison of changes in functional groups and molecular weights of cellulolytic enzyme lignins with different structural parameters, related to the recalcitrant properties of lignin, could be successfully altered during DAP conditions.

  3. Revealing the molecular structural transformation of hardwood and softwood in dilute acid flowthrough pretreatment

    SciTech Connect

    Zhang, Libing; Pu, Yunqiao; Cort, John R.; Ragauskas, Arthur J.; Yang, Bin

    2016-10-03

    To understand better the intrinsic recalcitrance of lignocellulosic biomass, the main hurdle to its efficient deconstruction, the effects of dilute acid flowthrough pretreatment on the dissolution chemistry of hemicellulose, cellulose, and lignin for both hardwood (e.g., poplar wood) and softwood (e.g., lodgepole pine wood) were investigated at temperatures of 200 to 270 °C and a flow rate of 25 mL/min with 0.05% (w/w) H2SO4. Results suggested that the softwood cellulose was more readily degraded into monomeric sugars than that of hardwood under same pretreatment conditions. However, while the hardwood lignin was completely removed into hydrolysate, ~30% of the softwood lignin remained as solid residues under identical conditions, which was plausibly caused by vigorous C5-active recondensation reactions (C–C5). As a result, effects of molecular structural features (i.e., lignin molecular weight, cellulose crystallinity, and condensed lignin structures) on the recalcitrance of hardwood and softwood to dilute acid pretreatment were identified for the first time in this study, providing important insights to establish the effective biomass pretreatment.

  4. 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

  5. Structural Transformation of Isolated Poplar and Switchgrass Lignins from Dilute Acid Pretreatment

    DOE PAGES

    Sun, Qining; Pu, Yunqiao; Meng, Xianzhi; ...

    2015-08-27

    A key step in conversion of cellulosic biomass into sustainable fuels and chemicals is thermochemical pretreatment to reduce plant cell wall recalcitrance. Obtaining an improved understanding of the fundamental chemistry of lignin, the most recalcitrant component of biomass, during pretreatment is critical to the continued development of renewable biofuel production. To examine the intrinsic chemistry of lignin during dilute acid pretreatment (DAP), lignin was isolated from poplar and switchgrass using a cellulolytic enzyme system and then treated under DAP conditions. These results highlight that lignin is subjected to depolymerization reactions within the first 2 min of dilute acid pretreatment andmore » these changes are accompanied by increased generation of aliphatic and phenolic hydroxyl groups of lignin. This is followed by a competing set of depolymerization and repolymerization reactions that lead to a decrease in the content of guaiacyl lignin units and an increase in condensed lignin units as the reaction residence time is extended beyond 5 min. Finally, we showed that a detailed comparison of changes in functional groups and molecular weights of cellulolytic enzyme lignins with different structural parameters, related to the recalcitrant properties of lignin, could be successfully altered during DAP conditions.« less

  6. Revealing the Molecular Structural Transformation of Hardwood and Softwood in Dilute Acid Flowthrough Pretreatment

    SciTech Connect

    Zhang, Libing; Pu, Yunqiao; Cort, John R.; Ragauskas, Arthur J.; Yang, Bin

    2016-12-05

    To better understand the intrinsic recalcitrance of lignocellulosic biomass, the main hurdle to its efficient deconstruction, the effects of dilute acid flowthrough pretreatment on the dissolution chemistry of hemicellulose, cellulose, and lignin for both hardwood (e.g. poplar wood) and softwood (e.g. lodgepole pine wood) were investigated at temperatures of 200 °C to 270 °C and a flow rate of 25 mL/minute with 0.05% (w/w) H2SO4. Results suggested that the softwood cellulose was more readily to be degraded into monomeric sugars than that of hardwood under same pretreatment conditions. However, while the hardwood lignin was completely removed into hydrolysate, ~30% of the softwood lignin remained as solid residues under identical conditions, which was plausibly caused by vigorous C5-active recondensation reactions (C-C5). Unique molecular structural features that pronounced the specific recalcitrance of hardwood and softwood to dilute acid pretreatment were identified for the first time in this study, providing important insights to establish the effective biomass pretreatment.

  7. Dynamics and mass accommodation of HCl molecules on sulfuric acid-water surfaces.

    PubMed

    Behr, P; Scharfenort, U; Ataya, K; Zellner, R

    2009-09-28

    A molecular beam technique has been used to study the dynamics and mass accommodation of HCl molecules in collision with sulfuric acid-water surfaces. The experiments were performed by directing a nearly mono-energetic beam of HCl molecules onto a continuously renewed liquid film of 54-76 wt% sulfuric acid at temperatures between 213 K and 243 K. Deuterated sulfuric acid was used to separate sticking but non-reactive collisions from those that involved penetration through the phase boundary followed by dissociation and recombination with D+. The results indicate that the mass accommodation of HCl on sulfuric acid-water surfaces decreases sharply with increasing acidity over the concentration range 54-76 wt%. Using the capillary wave theory of mass accommodation this effect is explained by a change of the surface dynamics. Regarding the temperature dependence it is found that the mass accommodation of HCl increases with increasing temperature and is limited by the bulk phase viscosity and driven by the restoring forces of the surface tension. These findings imply that under atmospheric conditions the uptake of HCl from the gas phase depends crucially on the bulk phase parameters of the sulfuric acid aerosol.

  8. Cluster Formation of Sulfuric Acid with Dimethylamine or Diamines and Detection with Chemical Ionization

    NASA Astrophysics Data System (ADS)

    Jen, C. N.; McMurry, P. H.; Hanson, D. R.

    2015-12-01

    Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to chemically ionize clusters for detection. In this study, we compare measured cluster concentrations formed by reacting sulfuric acid vapor with dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine) using nitrate and acetate ions. We show from flow reactor measurements that nitrate is unable to chemically ionize clusters with weak acidities. In addition, we vary the ion-molecule reaction time to probe the chemical ionization processes and lifetimes of ions composed of sulfuric acid and base molecules. We then model the neutral and ion cluster formation pathways, including chemical ionization, ion-induced clustering, and ion decomposition, to better identify which cluster types cannot be chemically ionized by nitrate. Our results show that sulfuric acid dimer with two diamines and sulfuric acid trimer with 2 or more base molecules cannot be chemical ionized by nitrate. We conclude that cluster concentrations measured with acetate CI gives a better representation of both cluster abundancies and their base content than nitrate CI.

  9. Comparison of microwaves to fluidized sand baths for heating tubular reactors for hydrothermal and dilute acid batch pretreatment of corn stover.

    PubMed

    Shi, Jian; Pu, Yunqiao; Yang, Bin; Ragauskas, Arthur; Wyman, Charles E

    2011-05-01

    Heating of batch tubular reactors with fluidized sand baths and with microwaves resulted in distinctive sugar yield profiles from pretreatment and subsequent enzymatic hydrolysis of corn stover at the same time, temperature, and dilute sulfuric acid concentration combinations and hydrothermal pretreatment conditions. Microwave heated pretreatment led to faster xylan, lignin, and acetyl removal as well as earlier xylan degradation than sand baths, but maximum sugar recoveries were similar. Solid state CP/MAS NMR revealed that microwave heating was more effective in altering cellulose structural features especially in breakdown of amorphous regions of corn stover than sand bath heating. Enzymatic hydrolysis of pretreated corn stover was improved by microwave heating compared to sand bath heating. Mechanisms were proposed to explain the differences in results for the two systems and provide new insights into pretreatment that can help advance this technology.

  10. 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.

  11. Separation of glycols from dilute aqueous solutions via complexation with boronic acids

    SciTech Connect

    Randel, L.A.; King, C.J.

    1991-07-01

    This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

  12. High titer ethanol production from simultaneous enzymatic saccharification and fermentation of aspen at high solids: a comparison between SPORL and dilute acid pretreatments.

    PubMed

    Zhu, J Y; Gleisner, R; Scott, C T; Luo, X L; Tian, S

    2011-10-01

    Native aspen (Populus tremuloides) was pretreated using sulfuric acid and sodium bisulfite (SPORL) and dilute sulfuric acid alone (DA). Simultaneous enzymatic saccharification and fermentation (SSF) was conducted at 18% solids using commercial enzymes with cellulase loadings ranging from 6 to 15 FPU/g glucan and Saccharomyces cerevisiae Y5. Compared with DA pretreatment, the SPORL pretreatment reduced the energy required for wood chip size-reduction, and reduced mixing energy of the resultant substrate for solid liquefaction. Approximately 60% more ethanol was produced from the solid SPORL substrate (211 L/ton wood at 59 g/L with SSF efficiency of 76%) than from the solid DA substrate (133 L/ton wood at 35 g/L with SSF efficiency 47%) at a cellulase loading of 10 FPU/g glucan after 120 h. When the cellulase loading was increased to 15 FPU/g glucan on the DA substrate, the ethanol yield still remained lower than the SPORL substrate at 10 FPU/g glucan.

  13. Distribution of Hydrogen Peroxide, Carbon Dioxide, and Sulfuric Acid in Europa's Icy Crust

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.

    2004-01-01

    Galileo's Near Infrared Mapping Spectrometer (NIMS) detected hydrogen peroxide, carbon dioxide and a hydrated material on Europa's surface, the latter interpreted as hydrated sulfuric acid (H2SO4*nH2O) or hydrated salts. Related compounds are molecular oxygen, sulfur dioxide, and two chromophores, one that is dark in the ultraviolet(UV) and concentrated on the trailing side, the other brighter in the UV and preferentially distributed in the leading hemisphere. The UV-dark material has been suggested to be sulfur.

  14. 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.

  15. The sulfuric acid leaching of Bayer electrofilter fines: A practical kinetical approach

    NASA Astrophysics Data System (ADS)

    Sancho Martínez, J. P.; Ayala, Espina J.; García Coque, M. P.; Fernández, Pérez B.; Costales, Alonso D.

    2006-08-01

    Electrofilter fines, which are by-products of the Bayer process for the production of alumina from bauxite, were characterized to evaluate the alumina that was potentially extractable with sulfuric acid. Acid leaching is carried out at different concentrations of sulfuric acid, at different temperatures, pulp densities, and times, to dissolve gibbsite and transition aluminas. The result is an aluminum sulfate solution. This article reports on a study of the kinetics of the leaching reaction at 90°C with two pulp densities: 10% and 30%.

  16. 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.

  17. The dissolution of quartz in dilute aqueous solutions of organic acids at 25°C

    USGS Publications Warehouse

    Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P.

    1988-01-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25° and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 μmole/Kg compared to 50 μmole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH.The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid anions which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  18. The dissolution of quartz in dilute aqueous solutions of organic acids at 25 degree C

    SciTech Connect

    Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P. )

    1988-06-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25{degree}C and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 {mu}mole/Kg compared to 50 {mu}mole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH. The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  19. Optimization of dilute acid-based pretreatment and application of laccase on apple pomace.

    PubMed

    Parmar, Indu; Rupasinghe, H P Vasantha

    2012-11-01

    The present study was aimed to optimize acid-based pretreatment of apple pomace in relation to acid concentration, temperature and reaction time using response surface method with glucose as response variable. In addition, laccase (EC. 1.10.3.2) from Trametes versicolor was applied for degradation of polyphenols in apple pomace that could inhibit the further bioconversion steps involving enzymes and fermenting micro-organisms. The optimized conditions were: 1.5 g/100mL acid concentration, 16 min reaction time and 91°C reaction temperature, producing 13.9 g glucose/100g on a dry matter basis. Subsequent application of laccase to hydrolyzates degraded most of the phenolic compounds in apple pomace by more than 85%. The optimized pretreatment conditions resulted in lower concentrations of other inhibitors such as furan compounds and acetic acid. Therefore, dilute acid pretreatment in combination with laccase application can be used for enhancing subsequent hydrolysis of polysaccharides and fermentation of apple pomace.

  20. Regeneration of basic sorbents used in the recovery of acetic acid from dilute aqueous solution

    SciTech Connect

    Ng, M.; King, C.J.

    1988-10-01

    The regeneration of basic sorbents used in the recovery of dilute aqueous acetic acid was explored. The regeneration methods studied were solvent leaching and vaporization. The resins used were weak base anion exchange resins, Dow Chemical Company's Dowex MWA-1 (tertiary amine resin) and Celanese Corporation's Aurorez (polybenzimidazole resin). The equilibrium between the aqueous acetic acid solution and the resins was measured in batch experiments. The composite isotherms calculated from these data wee comparable to those of other researchers. Methanol was used as the solvent to leach acetic acid from the resin. The equilibrium data from the batch experiments were used in the local-equilibrium theory of fixed-bed devices to model the desorption behavior of acetic acid in methanol. Both sorption and desorption equilibrium data were used in chemical complexation models to obtain sorption affinities and capacities of the resin for acetic acid. However, the amount of methanol needed to achieve a high degree of regeneration was too large to be economical. 15 refs., 25 figs., 3 tabs.

  1. New insights into sulfur amino acids function in gut health and disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acids (SAAs) metabolism in the body. Aside from their role in protein synthesis, methionine and cysteine are involved in many biological functions and diseases. Methionine (MET) is an indispensable amino acid and is...

  2. Sulfuric acid speleogenesis (SAS) close to the water table: Examples from southern France, Austria, and Sicily

    NASA Astrophysics Data System (ADS)

    De Waele, Jo; Audra, Philippe; Madonia, Giuliana; Vattano, Marco; Plan, Lukas; D'Angeli, Ilenia M.; Bigot, Jean-Yves; Anoux, Catherine; Nobécourt, Jean-Claude

    2016-01-01

    Caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings, from arid regions to mid-latitude and alpine areas. H2S is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers. In tectonically disturbed areas major fractures eventually allow these H2S-bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid. This extremely strong acid reacts with the carbonate bedrock creating caves, some of which are among the largest and most spectacular in the world. Production of sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and droplets in the cave environment. These caves are generated at or immediately above the water table, where condensation-corrosion processes are dominant, creating a set of characteristic meso- and micromorphologies. Due to their close connection to the base level, these caves can also precisely record past hydrological and geomorphological settings. Certain authigenic cave minerals, produced during the sulfuric acid speleogenesis (SAS) phase, allow determination of the exact timing of speleogenesis. This paper deals with the morphological, geochemical and mineralogical description of four very typical sulfuric acid water table caves in Europe: the Grotte du Chat in the southern French Alps, the Acqua Fitusa Cave in Sicily (Italy), and the Bad Deutsch Altenburg and Kraushöhle caves in Austria.

  3. Homogenous nucleation of sulfuric acid and water at close to atmospherically relevant conditions

    NASA Astrophysics Data System (ADS)

    Brus, D.; Neitola, K.; Hyvärinen, A.-P.; Petäjä, T.; Vanhanen, J.; Sipilä, M.; Paasonen, P.; Kulmala, M.; Lihavainen, H.

    2011-06-01

    In this study the homogeneous nucleation rates in the system of sulfuric acid and water were measured by using a flow tube technique. The goal was to directly compare particle formation rates obtained from atmospheric measurements with nucleation rates of freshly nucleated particles measured with particle size magnifier (PSM) which has detection efficiency of unity for particles having mobility diameter of 1.5 nm. The gas phase sulfuric acid concentration in this study was measured with the chemical ionization mass spectrometer (CIMS), commonly used in field measurements. The wall losses of sulfuric acid were estimated from measured concentration profiles along the flow tube. The initial concentrations of sulfuric acid estimated from loss measurements ranged from 108 to 3 × 109 molecules cm-3. The nucleation rates obtained in this study cover about three orders of magnitude from 10-1 to 102 cm-3 s-1 for commercial ultrafine condensation particle counter (UCPC) TSI model 3025A and from 101 to 104 cm-3 s-1 for PSM. The nucleation rates and the slopes (dlnJ/dln [H2SO4]) show satisfactory agreement when compared to empirical kinetic and activation models and the latest atmospheric nucleation data. To the best of our knowledge, this is the first experimental work providing temperature dependent nucleation rate measurements using a high efficiency particle counter with a cut-off-size of 1.5 nm together with direct measurements of gas phase sulfuric acid concentration.

  4. Ice core sulfur and methanesulfonic acid (MSA) records from southern Greenland document North American and European air pollution and suggest a decline in regional biogenic sulfur emissions.

    NASA Astrophysics Data System (ADS)

    Pasteris, D. R.; McConnell, J. R.; Burkhart, J. F.; Saltzman, E. S.

    2014-12-01

    Sulfate aerosols have an important cooling effect on the Earth because they scatter sunlight back to space and form cloud condensation nuclei. However, understanding of the atmospheric sulfur cycle is incomplete, leading to uncertainty in the assessment of past, present and future climate forcing. Here we use annually resolved observations of sulfur and methanesulfonic acid (MSA) concentration in an array of precisely dated Southern Greenland ice cores to assess the history of sulfur pollution emitted from North America and Europe and the history of biogenic sulfate aerosol derived from the North Atlantic Ocean over the last 250 years. The ice core sulfur time series is found to closely track sulfur concentrations in North American and European precipitation since records began in 1965, and also closely tracks estimated sulfur emissions since 1850 within the air mass source region as determined by back trajectory analysis. However, a decline to near-preindustrial sulfur concentrations in the ice cores after 1995 that is not so extensive in the source region emissions indicates that there has been a change in sulfur cycling over the last 150 years. The ice core MSA time series shows a decline of 60% since the 1860s, and is well correlated with declining sea ice concentrations around Greenland, suggesting that the phytoplankton source of biogenic sulfur has declined due to a loss of marginal sea ice zone habitat. Incorporating the implied decrease in biogenic sulfur in our analysis improves the match between the ice core sulfur record and the source region emissions throughout the last 150 years, and solves the problem of the recent return to near-preindustrial levels in the Greenland ice. These findings indicate that the transport efficiency of sulfur air pollution has been relatively stable through the industrial era and that biogenic sulfur emissions in the region have declined.

  5. Influence of pretreatment condition on the fermentable sugar production and enzymatic hydrolysis of dilute acid-pretreated mixed softwood.

    PubMed

    Lim, Woo-Seok; Lee, Jae-Won

    2013-07-01

    In this study, the effects of different acid catalysts and pretreatment factors on the hydrolysis of mixed softwood were investigated over a range of thermochemical pretreatments. Maleic, oxalic, and sulfuric acids were each used, under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid pretreatment of softwood was the pH. Reaction temperature was the next significant factor. However, during sulfuric acid pretreatment, fermentable sugar production was more dependent on reaction temperature, than time or pH. Enzymatic hydrolysis yields differed, depending on acid catalyst and pretreatment factor, regardless of lignin content in pretreated biomass. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 61.23%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to the fermentable sugar production in the hydrolysate.

  6. The effect of dilute acid pre-treatment process in bioethanol production from durian (Durio zibethinus) seeds waste

    NASA Astrophysics Data System (ADS)

    Ghazali, K. A.; Salleh, S. F.; Riayatsyah, T. M. I.; Aditiya, H. B.; Mahlia, T. M. I.

    2016-03-01

    Lignocellulosic biomass is one of the promising feedstocks for bioethanol production. The process starts from pre-treatment, hydrolysis, fermentation, distillation and finally obtaining the final product, ethanol. The efficiency of enzymatic hydrolysis of cellulosic biomass depends heavily on the effectiveness of the pre-treatment step which main function is to break the lignin structure of the biomass. This work aims to investigate the effects of dilute acid pre-treatment on the enzymatic hydrolysis of durian seeds waste to glucose and the subsequent bioethanol fermentation process. The yield of glucose from dilute acid pre-treated sample using 0.6% H2SO4 and 5% substrate concentration shows significant value of 23.4951 g/L. Combination of dilute acid pre-treatment and enzymatic hydrolysis using 150U of enzyme able to yield 50.0944 g/L of glucose content higher compared to normal pre-treated sample of 8.1093 g/L. Dilute acid pre-treatment sample also shows stable and efficient yeast activity during fermentation process with lowest glucose content at 2.9636 g/L compared to 14.7583g/L for normal pre-treated sample. Based on the result, it can be concluded that dilute acid pre-treatment increase the yield of ethanol from bioethanol production process.

  7. Death of a toddler due to ingestion of sulfuric acid at a clandestine home methamphetamine laboratory.

    PubMed

    Burge, Meredith; Hunsaker, John C; Davis, Gregory J

    2009-12-01

    Exposure to strong acids such as sulfuric acid to either the skin or the gastrointestinal or respiratory mucosa will result respectively in significant-occasionally fatal-cutaneous chemical burns as well as devastating corrosive damage to the respiratory and gastrointestinal tracts. Most injuries are accidental, but there are reports of using acids as weapons or as a means of suicide. The primary mechanism of acid injury is coagulative necrosis of the tissues. Sulfuric acid is a chemical often used in industrial and chemical laboratories, and it is an ingredient in household products like drain cleaner. Easily accessible, over-the-counter, household drain cleaner is one of several common materials used to manufacture methamphetamine. With increasing clandestine methamphetamine laboratories in the United States, exposure to methamphetamine and the toxic chemicals used for its production is a growing problem. In many instances, children living in these laboratories qua homes are at risk for injury and death. We report the death of an unattended toddler, who ingested sulfuric acid drain cleaner in his home. The gross and histopathological autopsy findings in this case are similar to those of previously described cases of sulfuric acid injury.

  8. Process for recovery of sulfur from acid gases

    DOEpatents

    Towler, Gavin P.; Lynn, Scott

    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.

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

    PubMed

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

    2010-05-15

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

  10. Diamine-sulfuric acid reactions are a potent source of new particle formation

    NASA Astrophysics Data System (ADS)

    Jen, Coty N.; Bachman, Ryan; Zhao, Jun; McMurry, Peter H.; Hanson, David R.

    2016-01-01

    Atmospheric nucleation from sulfuric acid depends on the concentrations and the stabilizing effect of other trace gases, such as ammonia and amines. Diamines are an understudied class of atmospherically relevant compounds, and we examine how they affect sulfuric acid nucleation in both flow reactor experiments and the atmosphere. The number of particles produced from sulfuric acid and diamines in the flow reactor was equal to or greater than the number formed from monoamines, implying that diamines are more effective nucleating agents. Upper limits of diamine abundance were also monitored during three field campaigns: Lamont, OK (2013); Lewes, DE (2012); and Atlanta, GA (2009). Mixing ratios were measured as high as tens of parts per trillion by volume (GA and OK). Laboratory results suggest that diamines at these levels are important for atmospheric nucleation. Diamines likely participate in atmospheric nucleation and should be considered in nucleation measurements and models.

  11. Reevaluating the contribution of sulfuric acid and the origin of organic compounds in atmospheric nanoparticle growth

    NASA Astrophysics Data System (ADS)

    Vakkari, Ville; Tiitta, Petri; Jaars, Kerneels; Croteau, Philip; Beukes, Johan Paul; Josipovic, Miroslav; Kerminen, Veli-Matti; Kulmala, Markku; Venter, Andrew D.; Zyl, Pieter G.; Worsnop, Douglas R.; Laakso, Lauri

    2015-12-01

    Aerosol particles formed in the atmosphere are important to the Earth's climate system due to their ability to affect cloud properties. At present, little is known about the atmospheric chemistry responsible for the growth of newly formed aerosol particles to climate-relevant sizes. Here combining detailed aerosol measurements with a theoretical framework we found that depending on the gaseous precursors and size of the newly formed particles, the growth was dominated by either sulfuric acid accompanied by ammonium or organic compounds originating in either biogenic emissions or savannah fires. The contribution of sulfuric acid was larger during the early phases of the growth, but in clean conditions organic compounds dominated the growth from 1.5 nm up to climatically relevant sizes. Furthermore, our analysis indicates that in polluted environments the contribution of sulfuric acid to the growth may have been underestimated by up to a factor of 10.

  12. 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.

  13. 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.

  14. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry.

    PubMed

    Rondo, L; Ehrhart, S; Kürten, A; Adamov, A; Bianchi, F; Breitenlechner, M; Duplissy, J; Franchin, A; Dommen, J; Donahue, N M; Dunne, E M; Flagan, R C; Hakala, J; Hansel, A; Keskinen, H; Kim, J; Jokinen, T; Lehtipalo, K; Leiminger, M; Praplan, A; Riccobono, F; Rissanen, M P; Sarnela, N; Schobesberger, S; Simon, M; Sipilä, M; Smith, J N; Tomé, A; Tröstl, J; Tsagkogeorgas, G; Vaattovaara, P; Winkler, P M; Williamson, C; Wimmer, D; Baltensperger, U; Kirkby, J; Kulmala, M; Petäjä, T; Worsnop, D R; Curtius, J

    2016-03-27

    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  15. 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.

  16. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-03-01

    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  17. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    PubMed Central

    Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-01-01

    Abstract Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit. PMID:27610289

  18. Controlled fed-batch fermentations of dilute-acid hydrolysate in pilot development unit scale.

    PubMed

    Rudolf, Andreas; Galbe, Mats; Lidén, Gunnar

    2004-01-01

    Inhibitors formed during wood hydrolysis constitute a major problem in fermenting dilute-acid hydrolysates. By applying a fed-batch technique, the levels of inhibitory compounds may be held low, enabling high ethanol productivity. In this study, a previously developed fed-batch strategy was modified and implemented for use in pilot development unit (PDU) scale. The rate of total gas formation, measured with a mass flow meter, was used as input variable in the control algorithm. The feed rate in the PDU-scale experiments could be properly controlled based on the gas evolution from the reactor. In fed-batch experiments utilizing TMB 3000, an inhibitor-tolerant strain of Saccharomyces cerevisiae, close to 100% of the hexoses in the hydrolysate was converted.

  19. Comparison of aqueous ammonia and dilute acid pretreatment of bamboo fractions: Structure properties and enzymatic hydrolysis.

    PubMed

    Xin, Donglin; Yang, Zhong; Liu, Feng; Xu, Xueru; Zhang, Junhua

    2015-01-01

    The effect of two pretreatments methods, aqueous ammonia (SAA) and dilute acid (DA), on the chemical compositions, cellulose crystallinity, morphologic change, and enzymatic hydrolysis of bamboo fractions (bamboo yellow, timber, green, and knot) was compared. Bamboo fractions with SAA pretreatment had better hydrolysability than those with DA pretreatment. High crystallinity index resulted in low hydrolysis yield in the conversion of SAA pretreated bamboo fractions, not DA pretreated fractions. The increase of cellulase loading had modestly positive effect in the hydrolysis of both SAA and DA pretreated bamboo fractions, while supplement of xylanase significantly increased the hydrolysis of the pretreated bamboo fractions, especially after SAA pretreatment. The results indicated that SAA pretreatment was more effective than DA pretreatment in conversion of bamboo fractions, and supplementation of xylanase was necessary in effective conversion of the SAA pretreated fractions into fermentable sugars.

  20. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    DOE PAGES

    Brodeur, G.; Telotte, J.; Stickel, J. J.; ...

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removesmore » the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.« less

  1. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    SciTech Connect

    Brodeur, G.; Telotte, J.; Stickel, J. J.; Ramakrishnan, S.

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  2. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing.

    PubMed

    Brodeur, G; Telotte, J; Stickel, J J; Ramakrishnan, S

    2016-11-01

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide - NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass - DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  3. Effects of Dilute Acid Pretreatment on Cellulose DP and the Relationship Between DP Reduction and Cellulose Digestibility

    SciTech Connect

    Wang, W.; Chen, X.; Tucker, M.; Himmel, M. E.; Johnson, D. K.

    2012-01-01

    The degree of polymerization(DP) of cellulose is considered to be one of the most important properties affecting the enzymatic hydrolysis of cellulose. Various pure cellulosic and biomass materials have been used in a study of the effect of dilute acid treatment on cellulose DP. A substantial reduction in DP was found for all pure cellulosic materials studied even at conditions that would be considered relatively mild for pretreatment. The effect of dilute acid pretreatment on cellulose DP in biomass samples was also investigated. Corn stover pretreated with dilute acid under the most optimal conditions contained cellulose with a DPw in the range of 1600{approx}3500, which is much higher than the level-off DP(DPw 150{approx}300) obtained with pure celluloses. The effect of DP reduction on the saccharification of celluloses was also studied. From this study it does not appear that cellulose DP is a main factor affecting cellulose saccharification.

  4. Ethanol production from cotton gin trash using optimised dilute acid pretreatment and whole slurry fermentation processes.

    PubMed

    McIntosh, S; Vancov, T; Palmer, J; Morris, S

    2014-12-01

    Cotton ginning trash (CGT) collected from Australian cotton gins was evaluated for bioethanol production. CGT composition varied between ginning operations and contained high levels of extractives (26-28%), acid-insoluble material (17-22%) and holocellulose (42-50%). Pretreatment conditions of time (4-20 min), temperature (160-220 °C) and sulfuric acid concentration (0-2%) were optimised using a central composite design. Response surface modelling revealed that CGT fibre pretreated at 180 °C in 0.8% H2SO4 for 12 min was optimal for maximising enzymatic glucose recoveries and achieved yields of 89% theoretical, whilst the total accumulated levels of furans and acetic acid remained relatively low at <1 and 2 g/L respectively. Response surface modelling also estimated maximum xylose recovery in pretreated liquors (87% theoretical) under the set conditions of 150 °C in 1.9% H2SO4 for 23.8 min. Yeast fermentations yielded high ethanol titres of 85%, 88% and 70% theoretical from glucose generated from: (a) enzymatic hydrolysis of washed pretreated fibres, (b) enzymatic hydrolysis of whole pretreated slurries and (c) simultaneous saccharification fermentations, respectively.

  5. 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.

  6. 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.

  7. The impacts of deacetylation prior to dilute acid pretreatment on the bioethanol process

    PubMed Central

    2012-01-01

    Background 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. PMID:22369467

  8. 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.

  9. Dynamic behavior of the bray-liebhafsky oscillatory reaction controlled by sulfuric acid and temperature

    NASA Astrophysics Data System (ADS)

    Pejić, N.; Vujković, M.; Maksimović, J.; Ivanović, A.; Anić, S.; Čupić, Ž.; Kolar-Anić, Lj.

    2011-12-01

    The non-periodic, periodic and chaotic regimes in the Bray-Liebhafsky (BL) oscillatory reaction observed in a continuously fed well stirred tank reactor (CSTR) under isothermal conditions at various inflow concentrations of the sulfuric acid were experimentally studied. In each series (at any fixed temperature), termination of oscillatory behavior via saddle loop infinite period bifurcation (SNIPER) as well as some kind of the Andronov-Hopf bifurcation is presented. In addition, it was found that an increase of temperature, in different series of experiments resulted in the shift of bifurcation point towards higher values of sulfuric acid concentration.

  10. Dilute acid pretreatment of black spruce using continuous steam explosion system.

    PubMed

    Fang, Haixia; Deng, James; Zhang, Tony

    2011-02-01

    The pretreatment of lignocellulosic materials prior to the enzymatic hydrolysis is essential to the sugar yield and bioethanol production. Dilute acid hydrolysis of black spruce softwood chip was performed in a continuous high temperature reactor followed with steam explosion and mechanical refining. The acid-soaked wood chips were pretreated under different feeding rates (60 and 92 kg/h), cooking screw rotation speeds (7.2 and 14.4 rpm), and steam pressures (12 and 15 bar). The enzymatic hydrolysis was carried out on the acid-insoluble fraction of pretreated material. At lower feeding rate, the pretreatment at low steam pressure and short retention time favored the recovery of hemicellulose. The pretreatment at high steam pressure and longer retention time recovered less hemicellulose but improved the enzymatic accessibility. As a result, the overall sugar yields became similar no matter what levels of the retention time or steam pressure. Comparing with lower feeding rate, higher feeding rate resulted in consistently higher glucose yield in both liquid fraction after pretreatment and that released after enzymatic hydrolysis.

  11. Ammonia Catalyzed Formation of Sulfuric Acid in Troposphere: The Curious Case of A Base Promoting Acid Rain.

    PubMed

    Bandyopadhyay, Biman; Kumar, Pradeep; Biswas, Partha

    2017-04-03

    Electronic structure calculations have been performed to investigate the role of ammonia in catalyzing the formation of sulfuric acid through hydrolysis of SO3 in Earth's atmosphere. The uncatalyzed process involves a high activation barrier and, till date, is mainly known to occur in Earth's atmosphere only when catalyzed by water and acids. Here we show that hydrolysis of SO3 can be very efficiently catalyzed by ammonia, the most abundant basic component in Earth's atmosphere. It was found, based on magnitude of relative potential energies as well as rate coefficients, that ammonia is the best among all the catalysts studied until now (water and acids) and could be a considerable factor in formation of sulfuric acid in troposphere. The calculated rate coefficient (at 298 K) of ammonia catalyzed reaction has been found to be ~10^5 - 10^7 times greater than that for water catalyzed ones. It was found, based on relative rates of ammonia and water catalyzed processes that in troposphere ammonia, together with water, could be the key factor in determining the rate of formation of sulfuric acid. In fact ammonia could surpass water in catalyzing formation of sulfuric acid via hydrolysis of SO3 at various altitudes in troposphere depending upon their relative concentrations.

  12. Acid-base thermochemistry of gaseous oxygen and sulfur substituted amino acids (Ser, Thr, Cys, Met).

    PubMed

    Riffet, Vanessa; Frison, Gilles; Bouchoux, Guy

    2011-11-07

    Acid-base thermochemistry of isolated amino acids containing oxygen or sulfur in their side chain (serine, threonine, cysteine and methionine) have been examined by quantum chemical computations. Density functional theory (DFT) was used, with B3LYP, B97-D and M06-2X functionals using the 6-31+G(d,p) basis set for geometry optimizations and the larger 6-311++G(3df,2p) basis set for energy computations. Composite methods CBS-QB3, G3B3, G4MP2 and G4 were applied to large sets of neutral, protonated and deprotonated conformers. Conformational analysis of these species, based on chemical approach and AMOEBA force field calculations, has been used to identify the lowest energy conformers and to estimate the population of conformers expected to be present at thermal equilibrium at 298 K. It is observed that G4, G4MP2, G3B3, CBS-QB3 composite methods and M06-2X DFT lead to similar conformer energies. Thermochemical parameters have been computed using either the most stable conformers or equilibrium populations of conformers. Comparison of experimental and theoretical proton affinities and Δ(acid)H shows that the G4 method provides the better agreement with deviations of less than 1.5 kJ mol(-1). From this point of view, a set of evaluated thermochemical quantities for serine, threonine, cysteine and methionine may be proposed: PA = 912, 919, 903, 938; GB = 878, 886, 870, 899; Δ(acid)H = 1393, 1391, 1396, 1411; Δ(acid)G = 1363, 1362, 1367, 1382 kJ mol(-1). This study also confirms that a non-negligible ΔpS° is associated with protonation of methionine and that the most acidic hydrogen of cysteine in the gas phase is that of the SH group. In several instances new conformers were identified thus suggesting a re-examination of several IRMPD spectra.

  13. Mechanisms of volatile production from sulfur-containing amino acids by irradiation

    NASA Astrophysics Data System (ADS)

    Uk Ahn, Dong; Joo Lee, Eun; Feng, Xi; Zhang, Wangang; Lee, Ji Hwan; Jo, Cheorun; Nam, Kichang

    2016-02-01

    Sulfur-containing amino acids were used to study the mechanisms of off-odor production in meat by irradiation. Irradiation not only increased the amounts of volatiles but also produced many new volatiles from sulfur-containing amino acid monomers. We speculate that the majority of the volatiles were the direct radiolytic products of the side chains, but Strecker degradation as well as deamination and decarboxylation of radiolytic products were also involved in the production of volatile compounds from sulfur amino acids. The volatile compounds produced in amino acids were not only the primary products of irradiation, but also the products of secondary chemical reactions after the primary compounds were produced. Cysteine and methionine produced odor characteristics similar to that of the irradiated meat, but the amounts of sulfur volatiles from methionine were far greater than that of cysteine. Although the present study was carried out using an amino acid model system, the information can be applied to the quality indexes of irradiated meats as well as other food products.

  14. 40 CFR 721.3130 - Sulfuric acid, mono-C9-11-alkyl esters, sodium salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sulfuric acid, mono-C9-11-alkyl esters... Specific Chemical Substances § 721.3130 Sulfuric acid, mono-C9-11-alkyl esters, sodium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  15. 40 CFR 721.3130 - Sulfuric acid, mono-C9-11-alkyl esters, sodium salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sulfuric acid, mono-C9-11-alkyl esters... Specific Chemical Substances § 721.3130 Sulfuric acid, mono-C9-11-alkyl esters, sodium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  16. 40 CFR 721.3130 - Sulfuric acid, mono-C9-11-alkyl esters, sodium salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sulfuric acid, mono-C9-11-alkyl esters... Specific Chemical Substances § 721.3130 Sulfuric acid, mono-C9-11-alkyl esters, sodium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  17. 40 CFR 721.3130 - Sulfuric acid, mono-C9-11-alkyl esters, sodium salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sulfuric acid, mono-C9-11-alkyl esters... Specific Chemical Substances § 721.3130 Sulfuric acid, mono-C9-11-alkyl esters, sodium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  18. 40 CFR 721.3130 - Sulfuric acid, mono-C9-11-alkyl esters, sodium salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Sulfuric acid, mono-C9-11-alkyl esters... Specific Chemical Substances § 721.3130 Sulfuric acid, mono-C9-11-alkyl esters, sodium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as...

  19. Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.

    PubMed

    Yao, Fang-Fang; Ding, Hui-Ming; Feng, Li-Li; Chen, Jing-Jing; Yang, Song-Yu; Wang, Xi-Hua

    2016-05-01

    A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability.

  20. 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.

  1. Free sulfurous acid (FSA) inhibition of biological thiosulfate reduction (BTR) in the sulfur cycle-driven wastewater treatment process.

    PubMed

    Qian, Jin; Wang, Lianlian; Wu, Yaoguo; Bond, Philip L; Zhang, Yuhan; Chang, Xing; Deng, Baixue; Wei, Li; Li, Qin; Wang, Qilin

    2017-06-01

    A sulfur cycle-based bioprocess for co-treatment of wet flue gas desulfurization (WFGD) wastes with freshwater sewage has been developed. In this process the removal of organic carbon is mainly associated with biological sulfate or sulfite reduction. Thiosulfate is a major intermediate during biological sulfate/sulfite reduction, and its reduction to sulfide is the rate-limiting step. In this study, the impacts of saline sulfite (the ionized form: HSO3(-) + SO3(2-)) and free sulfurous acid (FSA, the unionized form: H2SO3) sourced from WGFD wastes on the biological thiosulfate reduction (BTR) activities were thoroughly investigated. The BTR activity and sulfate/sulfite-reducing bacteria (SRB) populations in the thiosulfate-reducing up-flow anaerobic sludge bed (UASB) reactor decreased when the FSA was added to the UASB influent. Batch experiment results confirmed that FSA, instead of saline sulfite, was the true inhibitor of BTR. And BTR activities dropped by 50% as the FSA concentrations were increased from 8.0 × 10(-8) to 2.0 × 10(-4) mg H2SO3-S/L. From an engineering perspective, the findings of this study provide some hints on how to ensure effective thiosulfate accumulation in biological sulfate/sulfite reduction for the subsequent denitrification/denitritation. Such manipulation would result in higher nitrogen removal rates in this co-treatment process of WFGD wastes with municipal sewage.

  2. Pilot-scale On-farm Pretreatment of Perennial Grasses with Dilute Acid and Alkali for Fuel Ethanol Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Switchgrass (Panicum virgatum L.) and reed canarygrass (Phalaris arundinacea L.) were pretreated with sulfuric acid or calcium hydroxide 50 g/kg DM at both the laboratory (250 g DM) and pilot-scale (250 kg DM) and anaerobically stored for two durations, 60 and 180 days. Pretreated and untreated samp...

  3. Full-scale on-farm pretreatment of perennial grasses with dilute acid for fuel ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Producers utilizing sulfuric acid to pretreat biomass on-farm will need a safe and cost-effective method for application that does not negatively impact the ensiling process or harvesting capacity. To that end, switchgrass (Panicum virgatum L.) and reed canarygrass (Phalaris arundinacea L.) were pre...

  4. Assessment of nanofiltration and reverse osmosis potentialities to recover metals, sulfuric acid, and recycled water from acid gold mining effluent.

    PubMed

    Ricci, Bárbara C; Ferreira, Carolina D; Marques, Larissa S; Martins, Sofia S; Amaral, Míriam C S

    This work assessed the potential of nanofiltration (NF) and reverse osmosis (RO) to treat acid streams contaminated with metals, such as effluent from the pressure oxidation process (POX) used in refractory gold ore processing. NF and RO were evaluated in terms of rejections of sulfuric acid and metals. Regarding NF, high sulfuric acid permeation (∼100%), was observed, while metals were retained with high efficiencies (∼90%), whereas RO led to high acid rejections (<88%) when conducted in pH values higher than 1. Thus, sequential use of NF and RO was proved to be a promising treatment for sulfuric acid solutions contaminated by metals, such as POX effluent. In this context, a purified acid stream could be recovered in NF permeate, which could be further concentrated in RO. Recovered acid stream could be reused in the gold ore processing or commercialized. A metal-enriched stream could be also recovered in NF retentate and transferred to a subsequent metal recovery stage. In addition, considering the high acid rejection obtained through the proposed system, RO permeate could be used as recycling water.

  5. Chain-length heterogeneity allows for the assembly of fatty acid vesicles in dilute solutions.

    PubMed

    Budin, Itay; Prwyes, Noam; Zhang, Na; Szostak, Jack W

    2014-10-07

    A requirement for concentrated and chemically homogeneous pools of molecular building blocks would severely restrict plausible scenarios for the origin of life. In the case of membrane self-assembly, models of prebiotic lipid synthesis yield primarily short, single-chain amphiphiles that can form bilayer vesicles only at very high concentrations. These high critical aggregation concentrations (cacs) pose significant obstacles for the self-assembly of single-chain lipid membranes. Here, we examine membrane self-assembly in mixtures of fatty acids with varying chain lengths, an expected feature of any abiotic lipid synthesis. We derive theoretical predictions for the cac of mixtures by adapting thermodynamic models developed for the analogous phenomenon of mixed micelle self-assembly. We then use several complementary methods to characterize aggregation experimentally, and find cac values in close agreement with our theoretical predictions. These measurements establish that the cac of fatty acid mixtures is dramatically lowered by minor fractions of long-chain species, thereby providing a plausible route for protocell membrane assembly. Using an NMR-based approach to monitor aggregation of isotopically labeled samples, we demonstrate the incorporation of individual components into mixed vesicles. These experiments suggest that vesicles assembled in dilute, mixed solutions are depleted of the shorter-chain-length lipid species, a finding that carries implications for the composition of primitive cell membranes.

  6. 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.

  7. Inhibition effects of dilute-acid prehydrolysate of corn stover on enzymatic hydrolysis of Solka Floc.

    PubMed

    Kothari, Urvi D; Lee, Yoon Y

    2011-11-01

    Dilute-acid pretreatment liquor (PL) produced at NREL through a continuous screw-driven reactor was analyzed for sugars and other potential inhibitory components. Their inhibitory effects on enzymatic hydrolysis of Solka Floc were investigated. When the PL was mixed into the enzymatic hydrolysis reactor at 1:1 volume ratio, the glucan and xylan digestibility decreased by 63% and 90%, respectively. The tolerance level of the enzyme for each inhibitor was determined. Of the identified degradation components, acetic acid was found to be the strongest inhibitor for cellulase activity, as it decreased the glucan yield by 10% at 1 g/L. Among the sugars, cellobiose and glucose were found to be strong inhibitors to glucan hydrolysis, whereas xylose is a strong inhibitor to xylan hydrolysis. Xylo-oligomers inhibit xylan digestibility more strongly than the glucan digestibility. Inhibition by the PL was higher than that of the simulated mixture of the identifiable components. This indicates that some of the unidentified degradation components, originated mostly from lignin, are potent inhibitors to the cellulase enzyme. When the PL was added to a simultaneous saccharification and co-fermentation using Escherichia coli KO11, the bioprocess was severely inhibited showing no ethanol formation or cell growth.

  8. [Raman Spectra Study on Topochemistry in Miscanthus × giganteus Cell Walls During Dilute Acid Pretreatment].

    PubMed

    He, Chuan; Zhou, Xia; Yao, Chun-li; Xu, Feng

    2015-09-01

    Confocal Raman microspectroscopy (CRM) represents a powerful technique that can provide insights into topochemistry in lignocellulosic biomass cell wall. In this work, CRM was used to explore the impact of dilute acid (DA) pretreatment on the topochemistry of lignin and hydroxycinnamic acid (HCA) in the-fiber cell walls of Miscanthus × giganteus internode. Raman spectra extracted from different morphological regions of untreated fiber cell walls indicated the heterogeneous concentration of lignin and HCA. There is a companied trend between them, that is, regions where there is the higher lignin concentration have the higher concentration of HCA. When treated with DA, it was found that the intensity of 1600 cm(-1) (lignin) and 1170 cm(-1) (HCA) were decreased, which could be contributed to the partially removal of lignin and HCA. The removal rate in different morphological areas followed the decreasing order: secondary cell wall (SW) > compound middle lamella (CML) > cell corner middle lamella (CCML). The increase of the Raman band intensity ratio (1170/1600) indicated the preferential removal of lignin in the SW and CML as a result of DA pretreatment, while the constant of the ratio meant there is no preference between lignin and HCA in the CCML. The research will provide the deep understanding of the topochemistry of lignin and HCA at sub-cellular level during DA pretreatment, meanwhile, it also expands the application of Raman spectra in the research area of plant cell wall.

  9. New insights into sulfur amino acid function in gut health and disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acids (SAA) metabolism in the body. Aside from their role in protein synthesis, methionine and cysteine are involved in many biological functions and diseases. Methionine (MET) is an indispensable AA and is transmet...

  10. Kinetics of sulfuric acid leaching of cadmium from Cd-Ni zinc plant residues.

    PubMed

    Safarzadeh, Mohammad Sadegh; Moradkhani, Davood; Ojaghi-Ilkhchi, Mehdi

    2009-04-30

    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 the kinetics of cadmium dissolution in sulfuric acid were studied. The dissolution kinetics at 25-55 degrees C and tsulfuric acid concentration, solid/liquid ratio and particle size were also achieved. The rate of reaction at first 5 min based on diffusion-controlled process can be expressed by a semi-empirical equation as:It was determined that the dissolution rate increased with increasing sulfuric acid concentration and decreasing particle size.

  11. Chemical ionization of clusters formed from sulfuric acid and dimethylamine or diamines

    NASA Astrophysics Data System (ADS)

    Jen, Coty N.; Zhao, Jun; McMurry, Peter H.; Hanson, David R.

    2016-10-01

    Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to deprotonate and thus chemically ionize the clusters. In this study, we compare cluster concentrations measured using either nitrate or acetate. Clusters were formed in a flow reactor from vapors of sulfuric acid and dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine). These comparisons show that nitrate is unable to chemically ionize clusters with high base content. In addition, we vary the ion-molecule reaction time to probe ion processes which include proton-transfer, ion-molecule clustering, and decomposition of ions. Ion decomposition upon deprotonation by acetate/nitrate was observed. More studies are needed to quantify to what extent ion decomposition affects observed cluster content and concentrations, especially those chemically ionized with acetate since it deprotonates more types of clusters than nitrate.Model calculations of the neutral and ion cluster formation pathways are also presented to better identify the cluster types that are not efficiently deprotonated by nitrate. Comparison of model and measured clusters indicate that sulfuric acid dimers with two diamines and sulfuric acid trimers with two or more base molecules are not efficiently chemical ionized by nitrate. We conclude that acetate CI provides better information on cluster abundancies and their base content than nitrate CI.

  12. Sulfur amino acid deficiency upregulates intestinal methionine cycle activity and suppresses epithelial growth in neonatal pigs.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We recently showed that the developing gut is a significant site of methionine transmethylation to homocysteine and transsulfuration to cysteine. We hypothesized that sulfur amino acid (SAA) deficiency would preferentially reduce mucosal growth and antioxidant function in neonatal pigs. Neonatal pi...

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

    SciTech Connect

    Kurten, T.; Kuang, C.; Gomez, P.; McMurry, P. H.; Vehkamaki, H.; Ortega, I.; Noppel, M.; Kulmala, M.

    2010-01-11

    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.

  14. Improved process for the production of cellulose sulfate using sulfuric acid/ethanol solution.

    PubMed

    Chen, Guo; Zhang, Bin; Zhao, Jun; Chen, Hongwen

    2013-06-05

    An improved process for production of cellulose sulfate (CS) was developed by using sulfuric acid/ethanol solution as sulfonating agent and Na2SO4 as water absorbent. The FTIR, SEM and TG analysis were used to characterize the CS prepared. The total degree of substitution and viscosity of the product solution (2%, w/v) were ranging from 0.28 to 0.77 and from 115 to 907 mPa s, respectively, by changing the process parameters such as the amount of Na2SO4, the reaction time, the temperature, the sulfuric acid/alcohol ratio and liquid/solid ratio. The results indicated that the product with DS (0.28-0.77) and η2% (115-907) mPa s could be produced by using this improved process and more cellulose sulfate could be produced when cellulose was sulfonated for 3-4 h at -2 °C in sulfuric acid/ethanol (1.4-1.6) solution with addition of 0.8 g Na2SO4. The (13)C NMR indicated that the sulfate group of CS produced using sulfuric acid/ethanol solution was at C6 position.

  15. 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...

  16. Seed storage protein deficiency improves sulfur amino acid content in common bean (Phaseolus vulgaris L.): redirection of sulfur from gamma-glutamyl-S-methyl-cysteine.

    PubMed

    Taylor, Meghan; Chapman, Ralph; Beyaert, Ronald; Hernández-Sebastià, Cinta; Marsolais, Frédéric

    2008-07-23

    The contents of sulfur amino acids in seeds of common bean ( Phaseolus vulgaris L.) are suboptimal for nutrition. They accumulate large amounts of a gamma-glutamyl dipeptide of S-methyl-cysteine, a nonprotein amino acid that cannot substitute for methionine or cysteine in the diet. Protein accumulation and amino acid composition were characterized in three genetically related lines integrating a progressive deficiency in major seed storage proteins, phaseolin, phytohemagglutinin, and arcelin. Nitrogen, carbon, and sulfur contents were comparable among the three lines. The contents of S-methyl-cysteine and gamma-glutamyl-S-methyl-cysteine were progressively reduced in the mutants. Sulfur was shifted predominantly to the protein cysteine pool, while total methionine was only slightly elevated. Methionine and cystine contents (mg per g protein) were increased by up to ca. 40%, to levels slightly above FAO guidelines on amino acid requirements for human nutrition. These findings may be useful to improve the nutritional quality of common bean.

  17. Binary nucleation in acid-water systems. II. Sulfuric acid-water and a comparison with methanesulfonic acid-water

    NASA Astrophysics Data System (ADS)

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

    1991-05-01

    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. Flagan, and K. Okuyama, J. Chem. Phys. (submitted)]. Experiments were conducted at relative humidities (Rh) ranging from 0.006acidities (Ra) in the range of 0.04acid molecules in the critical nucleus for both the H2SO4 -water and MSA-water systems.

  18. Competitive Oxidation Kinetics and Microbial Ecology: Intermediate Sulfur Transformations in Acid Mine Drainage Environments

    NASA Astrophysics Data System (ADS)

    Druschel, G. K.; Hamers, R. J.; Banfield, J. F.

    2001-12-01

    Experimental studies have demonstrated that oxidation of pyrite proceeds through several intermediate sulfur species, notably elemental sulfur, thiosulfate, and polythionates (Schippers et al., 1996). However, detailed sampling and analysis of flowing waters and pore waters failed to detect intermediate sulfur species in the 5-way area of the Richmond metal sulfide deposit at the Iron Mountain Mine in northern California. Potential energy available from the oxidation of intermediate sulfur species is considerable, so microbial activity may explain absence of intermediate sulfur compounds at the site. However, the abundance of sulfur-oxidizing microorganisms in areas of active pyrite oxidation at the 5-way is generally low (Bond et al. 2000). Rapid inorganic oxidation rates may prevent microorganisms from utilizing these intermediate sulfur species, thus shaping the structure of microbial communities in acid mine drainage (AMD) environments. Rates and mechanisms of oxidation for tetrathionate and elemental sulfur have been experimentally determined. Batch and flow-through experiments have indicated very slow oxidation of elemental sulfur in inorganic solutions analogous to AMD environments. Results for tetrathionate indicate the importance of non-metabolic and inorganic processes, including surface catalysis and the generation of hydroxyl radicals. Surface catalysis occurs through trithionate on iron oxide surfaces. Hydroxyl radicals may be formed directly by microbes living in proximity to pyrite surfaces, or at pyrite surfaces undergoing wetting and drying cycles. Further experiments investigating the importance of organic compounds associated with iron-oxidizing microorganisms acting as electron transport shuttles and/or wetting agents and ab initio calculations of the electronic structure of potential reactants and intermediates are currently being performed. It is suggested that inorganic processes involved with seasonal wetting and drying of pyritic sediment

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

    SciTech Connect

    Ryu, Chang Seon; Kwak, Hui Chan; Lee, Kye Sook; Kang, Keon Wook; Oh, Soo Jin; Lee, Ki Ho; Kim, Hwan Mook; Ma, Jin Yeul; Kim, Sang Kyum

    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

  20. 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.

  1. THE EFFECT OF ANOLYTE PRODUCT ACID CONCENTRATION ON HYBRID SULFUR CYCLE PERFORMANCE

    SciTech Connect

    Gorensek, M.; Summers, W.

    2010-03-24

    The Hybrid Sulfur (HyS) cycle (Fig. 1) is one of the simplest, all-fluids thermochemical cycles that has been devised for splitting water with a high-temperature nuclear or solar heat source. It was originally patented by Brecher and Wu in 1975 and extensively developed by Westinghouse in the late 1970s and early 1980s. As its name suggests, the only element used besides hydrogen and oxygen is sulfur, which is cycled between the +4 and +6 oxidation states. HyS comprises two steps. One is the thermochemical (>800 C) decomposition of sulfuric acid (H{sub 2}SO{sub 4}) to sulfur dioxide (SO{sub 2}), oxygen (O{sub 2}), and water. H{sub 2}SO{sub 4} = SO{sub 2} + 1/2 O{sub 2} + H{sub 2}O. The other is the SO{sub 2}-depolarized electrolysis of water to H{sub 2}SO{sub 4} and hydrogen (H{sub 2}), SO{sub 2} + 2 H{sub 2}O = H{sub 2}SO{sub 4} + H{sub 2}, E{sup o} = -0.156 V, explaining the 'hybrid' designation. These two steps taken together split water into H{sub 2} and O{sub 2} using heat and electricity. Researchers at the Savannah River National Laboratory (SRNL) and at the University of South Carolina (USC) have successfully demonstrated the use of proton exchange membrane (PEM) electrolyzers (Fig. 2) for the SO{sub 2}-depolarized electrolysis (sulfur oxidation) step, while Sandia National Laboratories (SNL) successfully demonstrated the high-temperature sulfuric acid decomposition (sulfur reduction) step using a bayonet-type reactor (Fig. 3). This latter work was performed as part of the Sulfur-Iodine (SI) cycle Integrated Laboratory Scale demonstration at General Atomics (GA). The combination of these two operations results in a simple process that will be more efficient and cost-effective for the massive production of hydrogen than alkaline electrolysis. Recent developments suggest that the use of PEMs other than Nafion will allow sulfuric acid to be produced at higher concentrations (>60 wt%), offering the possibility of net thermal efficiencies around 50% (HHV basis

  2. Response surface optimization of corn stover pretreatment using dilute phosphoric acid for enzymatic hydrolysis and ethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dilute H3PO4 (0.0 - 2.0%, v/v) was used to pretreat corn stover (10%, w/w) for conversion to ethanol. Pretreatment conditions were optimized for temperature, acid loading, and time using a central composite design. Optimal pretreatment conditions were chosen to promote sugar yields following enzym...

  3. Parenteral sulfur amino acid requirements in septic infants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To investigate parenteral methionine requirements of critically ill, septic infants, we conducted an investigation involving 12 infants (age 2+/-1 years; weight 13+/-2kg) using the intravenous indicator amino acid oxidation and balance technique. They received a balanced parenteral amino acid formul...

  4. On the growth of nitric and sulfuric acid aerosol particles under stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Turco, R. P.; Toon, O. B.

    1988-01-01

    A theory for the formation of frozen aerosol particles in the Antarctic stratosphere was developed and applied to the formation of polar stratospheric clouds. The theory suggests that the condensed ice particles are composed primarily of nitric acid and water, with small admixtures of sulfuric and hydrochloric acids in solid solution. The proposed particle formation mechanism is in agreement with the magnitude and seasonal behavior of the optical extinction observed in the winter polar stratosphere.

  5. Simultaneous determination of four sulfur mustard-DNA adducts in rabbit urine after dermal exposure by isotope-dilution liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Yajiao; Yue, Lijun; Nie, Zhiyong; Chen, Jia; Guo, Lei; Wu, Bidong; Feng, Jianlin; Liu, Qin; Xie, Jianwei

    2014-06-15

    Sulfur mustard (SM) is a classic vesicant agent, which has been greatly employed in several wars or military conflicts. The most lesion mechanism is its strong alkylation of DNAs in vivo. Until now there are four specific DNA adducts of SM identified for further retrospective detection, i.e., N(7)-(2-hydroxyethylthioethyl)-2'-guanine (N(7)-HETEG), bis(2-ethyl-N(7)-guanine)thioether (Bis-G), N(3)-(2-hydroxyethylthioethyl)-2'-adenine (N(3)-HETEA) and O(6)-(2-hydroxyethylthioethyl)-2'-guanine (O(6)-HETEG), respectively. Here, a novel and sensitive method of isotope-dilution ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combining with solid phase extraction was reported for the simultaneous determination of four SM-DNA adducts. A lower limit of detection of 2-5ngL(-1), and a lower limit of quantitation of 5-10ngL(-1) were achieved, respectively, and the recoveries ranged from 87% to 116%. We applied this method in the determination of four SM-DNA adducts in rabbit urine after dermal exposure by SM in three dose levels (2, 5, 15mgkg(-1)), so as to investigate the related metabolic behavior in vivo. For the first time, in SM exposed rabbit urine, our results revealed the relative accumulation abundance of four SM-DNA adducts, i.e., 67.4% for N(7)-HETEG, 22.7% for Bis-G, 9.8% for N(3)-HETEA, 0.1% for O(6)-HETEG, and significant dose and time dependent responses of these SM-DNA adducts. The four adducts were detectable after 8h, afterwards, their contents continuously increased, achieved maximum in the first two or three days and then gradually decreased till the end of one month. Meanwhile, the amounts of SM-DNA adducts were positively correlated with the exposure doses.

  6. 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.

  7. Quantitative assessment of the sulfuric acid contribution to new particle growth.

    PubMed

    Bzdek, Bryan R; Zordan, Christopher A; Pennington, M Ross; Luther, George W; Johnston, Murray V

    2012-04-17

    The Nano Aerosol Mass Spectrometer (NAMS) was deployed to rural/coastal and urban sites to measure the composition of 20-25 nm diameter nanoparticles during new particle formation (NPF). NAMS provides a quantitative measure of the elemental composition of individual, size-selected nanoparticles. In both environments, particles analyzed during NPF were found to be enhanced in elements associated with inorganic species (nitrogen, sulfur) relative to that associated with organic species (carbon). A molecular apportionment algorithm was applied to the elemental data in order to place the elemental composition into a molecular context. These measurements show that sulfate constitutes a substantial fraction of total particle mass in both environments. The contribution of sulfuric acid to new particle growth was quantitatively determined and the gas-phase sulfuric acid concentration required to incorporate the measured sulfate fraction was calculated. The calculated values were compared to those calculated by a sulfuric acid proxy that considers solar radiation and SO(2) levels. The two values agree within experimental uncertainty. Sulfate accounts for 29-46% of the total mass growth of particles. Other species contributing to growth include ammonium, nitrate, and organics. For each location, the relative amounts of these species do not change significantly with growth rate. However, for the coastal location, sulfate contribution increases with increasing temperature whereas nitrate contribution decreases with increasing temperature.

  8. Development of Sulfuric Acid Decomposer for Thermo-Chemical IS Process

    SciTech Connect

    Hiroki, Noguchi; Hiroyuki, Ota; Atsuhiko, Terada; Shinji, Kubo; Kaoru, Onuki; Ryutaro, Hino

    2006-07-01

    The Japan Atomic Energy Agency (JAEA) has been conducting R and D on thermo-chemical Iodine-Sulfur (IS) process, which is one of most attractive water-splitting hydrogen production methods using nuclear heat of a high-temperature gas-cooled reactor (HTGR). In the IS process, sulfuric acid is evaporated and decomposed into H{sub 2}O and SO{sub 3} in a sulfuric acid decomposer operated under high temperature condition up to 500 deg C. Necessary heat is supplied by high temperature helium gas from the HTGR. Since the sulfuric acid decomposer will be exposed to severe corrosion condition, we have proposed a new decomposer concept of a block type heat exchanger made of SiC ceramic which has excellent corrosion and mechanical strength performance. To verify the concept, integrity of new type gaskets applied for boundary seal of the decomposer was examined as a first step. Pure gold gaskets coupled with absorption mechanism against thermal expansion showed good seal performance under 500 deg C. Based on this result, a mock-up model for a IS pilot-plant with 30 m{sup 3}/h-hydrogen production rate was test-fabricated as the next step. Through the fabrication and gas-tight tests, fabricability and structural integrity were confirmed. Also, the decomposer showed good mechanical strength and seal performances against horizontal loading simulating earthquake motion. (authors)

  9. 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

  10. Conversion of distiller's grain into fuel alcohol and a higher-value animal feed by dilute-acid pretreatment.

    PubMed

    Tucker, Melvin P; Nagle, Nicholas J; Jennings, Edward W; Ibsen, Kelly N; Aden, Andy; Nguyen, Quang A; Kim, Kyoung H; Noll, Sally L

    2004-01-01

    Over the past three decades ethanol production in the United States has increased more than 10-fold, to approx 2.9 billion gal/yr (mid-2003), with ethanol production expected to reach 5 billion gal/yr by 2005. The simultaneous coproduction of 7 million t/yr of distiller's grain (DG) may potentially drive down the price of DG as a cattle feed supplement. The sale of residual DG for animal feed is an important part of corn dry-grind ethanol production economics; therefore, dry-grind ethanol producers are seeking ways to improve the quality of DG to increase market penetration and help stabilize prices. One possible improvement is to increase the protein content of DG by converting the residual starch and fiber into ethanol. We have developed methods for steam explosion, SO2, and dilute-sulfuric acid pretreatment of DG for evaluation as a feedstock for ethanol production. The highest soluble sugar yields (approximately 77% of available carbohydrate) were obtained by pretreatment of DG at 140 degrees C for 20 min with 3.27 wt% H2SO4. Fermentation protocols for pretreated DG were developed at the bench scale and scaled to a working volume of 809 L for production of hydrolyzed distiller's grain (HDG) for feeding trials. The pretreated DG was fermented with Saccharomyces cerevisiae D5A, with ethanol yields of 73% of theoretical from available glucans. The HDG was air-dried and used for turkey-feeding trials. The inclusion of HDG into turkey poult (as a model non-ruminant animal) diets at 5 and 10% levels, replacing corn and soybean meal, showed weight gains in the birds similar to controls, whereas 15 and 20% inclusion levels showed slight decreases (-6%) in weight gain. At the conclusion of the trial, no negative effects on internal organs or morphology, and no mortality among the poults, was found. The high protein levels (58-61%) available in HDG show promising economics for incorporation of this process into corn dry-grind ethanol plants.

  11. Decoupling the Impacts of Heterotrophy and Autotrophy on Sulfuric Acid Speleogenesis

    NASA Astrophysics Data System (ADS)

    Jones, A. A.; Bennett, P.

    2013-12-01

    Within caves such as Movile Caves (Romania), the Frasassi Caves (Italy), and Lower Kane Cave (LKC, Wyoming, USA) the combination of abiotic autoxidation and microbiological oxidation of H2S produces SO42- and H+ that promotes limestone dissolution through sulfuric-acid speleogenesis (SAS). Microbial sulfide oxidation by sulfur-oxidizing bacteria (SOB) has been shown recently to be the dominant process leading to speleogenesis in these caves. However, due to the inherently large diversity of microbial communities within these environments, there are a variety of metabolic pathways that can impact limestone dissolution and carbon cycling to varying degrees. In order to investigate these variations we outfitted a continuous flow bioreactor with a Picarro Wavelength-Scanned Cavity Ring Down Spectrometer (WS-CRDS) that continuously monitored and logged 12CO2 and 13CO2 at ppmv sensitivity and isotope ratios at <0.3‰ precision in simulated cave atmospheres. Bioreactors containing Madison Limestone were inoculated with either a monoculture of the mixotrophic sulfur-oxidizing Thiothrix unzii or a mixed environmental (LKC) sulfur-metabolizing community. Ca2+ and pH were also continuously logged in order to quantify the impact of microbial metabolism on limestone dissolution rate. We found an order of magnitude of variability in limestone dissolution rates that were closely tied to microbial metabolism. In monocultures, limestone dissolution was inhibited by excessive reduced sulfur as T. unzii prefers to store sulfur internally as So under these conditions, generating no acidity. The headspace was depleted in 13C when sulfur was being stored as So and enriched in 13C when sulfur was being converted to SO42-. This suggests a preference for a heterotrophy during periods of high sulfur input and autotrophy when sulfur input is low. This was corroborated by an increase in SO42- during low sulfide input and microscope images showed loss of internal sulfur within the filaments

  12. 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.

  13. A Combined Proteomic and Transcriptomic Analysis on Sulfur Metabolism Pathways of Arabidopsis thaliana under Simulated Acid Rain

    PubMed Central

    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

  14. Characterization of shortday onion cultivars of 3 pungency levels with flavor precursor, free amino acid, sulfur, and sugar contents.

    PubMed

    Lee, Eun Jin; Yoo, Kil Sun; Jifon, John; Patil, Bhimanagouda S

    2009-08-01

    This study was conducted to characterize shortday onions of 3 pungency levels with regard to the composition of flavor related compounds. A total of 9 onion breeding lines/cultivars were selected, per each of low, medium, and high pungency level, with pyruvic acid contents of 1.9 to 2.8, 4.8 to 5.4, and 7.2 to 8.3 micromoles/mL, respectively. The contents of flavor precursors (S-1-propenyl-L-cysteine sulfoxide [1-PeCSO] and S-methyl-L-cysteine-sulfoxide [MCSO]), free amino acids, free sugars, soluble solids (SSC), and total sulfur (S) in onion bulbs were measured. The flavor precursor contents ranged from 0.03 to 0.16 mg/g fresh weight (FW) for MCSO, 0.07 to 0.65 mg for 1-PeCSO, and 0.12 to 0.77 mg in total, and precursor contents increased with the pungency levels. Onions of different pungency levels did not differ in the contents of individual or total free amino acids, and the most abundant amino acids were glutamine and arginine. The total sugar contents ranged from 50 to 75 mg/g FW, and total S contents (3.5 to 5.1 mg/g dry weight) were not correlated with the pungency levels. However, pungency levels were correlated inversely with bulb weight and positively with SSC, presumably by the effect of dilution. This study indicates that onion pungency is primarily determined by the content of flavor precursor compounds and not by total S, total sugars, or individual/total free amino acids in shortday bulbs.

  15. Investigating Mass Transport Limitations on Xylan Hydrolysis During Dilute Acid Pretreatment of Poplar

    SciTech Connect

    Mittal, Ashutosh; Pilath, Heid M.; Parent, Yves; Chatterjee, Siddharth G.; Donohoe, Bryon S.; Yarbrough, John M.; Himmel, Michael E.; Nimlos, Mark R.; Johnson, David K.

    2014-04-28

    Mass transport limitations could be an impediment to achieving high sugar yields during biomass pretreatment and thus be a critical factor in the economics of biofuels production. The objective of this work was to study the mass transfer restrictions imposed by the structure of biomass on the hydrolysis of xylan during dilute acid pretreatment of biomass. Mass transfer effects were studied by pretreating poplar wood at particle sizes ranging from 10 micrometers to 10 mm. This work showed a significant reduction in the rate of xylan hydrolysis in poplar when compared to the intrinsic rate of hydrolysis for isolated xylan that is possible in the absence of mass transfer. In poplar samples we observed no significant difference in the rates of xylan hydrolysis over more than two orders of magnitude in particle size. It appears that no additional mass transport restrictions are introduced by increasing particle size from 10 micrometers to 10 mm. This work suggests that the rates of xylan hydrolysis in biomass particles are limited primarily by the diffusion of hydrolysis products out of plant cell walls. A mathematical description is presented to describe the kinetics of xylan hydrolysis that includes transport of the hydrolysis products through biomass into the bulk solution. The modeling results show that the effective diffusion coefficient of the hydrolysis products in the cell wall is several orders of magnitude smaller than typical values in other applications signifying the role of plant cell walls in offering resistance to diffusion of the hydrolysis products.

  16. Methane Production from Rice Straw Hydrolysate Treated with Dilute Acid by Anaerobic Granular Sludge.

    PubMed

    Cheng, Jing-Rong; Liu, Xue-Ming; Chen, Zhi-Yi

    2016-01-01

    The traditional anaerobic digestion process of straw to biogas faces bottlenecks of long anaerobic digestion time, low digestion rate, less gas production, etc., while straw hydrolysate has the potential to overcome these drawbacks. In this study, the dilute sulphuric acid-treated hydrolysate of rice straw (DSARSH) containing high sulfate was firstly proved to be a feasible substrate for methane production under mesophilic digestion by granular sludge within a short digestion time. Batch anaerobic digestion process was operated under different initial chemical oxygen demand (COD) values at temperature of 37 °C with the pH of 8.5. Among the initial COD values ranging from 3000 to 11,000 mg/L, 5000 mg/L was proved to be the most appropriate considering high COD removal efficiency (94.17 ± 1.67 %), CH4 content (65.52 ± 3.12 %), and CH4 yield (0.346 ± 0.008 LCH4/g COD removed) within 120 h. Furthermore, when the studied system operated at the initial COD of 5000 mg/L, the sulfate removal ratio could reach 56.28 %.

  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.

  18. Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.

    PubMed

    Chen, Haihan; Grassian, Vicki H

    2013-09-17

    Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.

  19. 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.

  20. Effect of Mineral Admixtures on Resistance to Sulfuric Acid Solution of Mortars with Quaternary Binders

    NASA Astrophysics Data System (ADS)

    Makhloufi, Zoubir; Bederina, Madani; Bouhicha, Mohamed; Kadri, El-Hadj

    This research consists to study the synergistic action of three mineral additions simultaneously added to the cement. This synergistic effect has a positive effect on the sustainability of limestone mortars. Tests were performed on mortars based on crushed limestone sand and manufactured by five quaternary binders (ordinary Portland cement and CPO mixed simultaneously with filler limestone, blast-furnace and natural pozzolan). The purpose of this research was to identify the resistance of five different mortars to the solution of sulfuric acid. Changes in weight loss and compressive strength measured at 30, 60, 90, 120 and 180 days for each acid solution were studied. We followed up on the change in pH of the sulfuric acid solution at the end of each month up to 180 days.

  1. Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

    NASA Astrophysics Data System (ADS)

    Lin, Qing-quan; Gu, Guo-hua; Wang, Hui; Zhu, Ren-feng; Liu, You-cai; Fu, Jian-gang

    2016-05-01

    In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfuric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leaching efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sulfuric acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respectively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent activation energy of 12.28 kJ·mol-1. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSO4·H2O.

  2. Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

    NASA Astrophysics Data System (ADS)

    Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

    2016-04-01

    An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

  3. Separation of hafnium from zirconium in sulfuric acid solutions using pressurized ion exchange

    SciTech Connect

    Hurst, F.J.

    1981-01-01

    High-resolution pressurized ion exchange has been used successfully to study and separate hafnium and zirconium sulfate complexes by chromatographic elution from Dowex 50W-X8 (15 to 25 ..mu..m) resin with sulfuric acid solutions. Techniques were developed to continuously monitor the column effluents for zirconium and hafnium by reaction with fluorometric and colorimetric reagents. Since neither reagent was specific for either metal ion, peak patterns were initially identified by using the stable isotopes /sup 90/Zr and /sup 180/Hf as fingerprints of their elution position. Distribution ratios for both zirconium and hafnium decrease as the inverse fourth power of the sulfuric acid concentration below 2N and as the inverse second power at higher acid concentration. The hafnium-to-zirconium separation factor is approximately constant (approx. 8) over the 0.5 to 3N range. Under certain conditions, an unseparated fraction was observed that was not retained by the resin. The amount of this fraction which is thought to be a polymeric hydrolysis product appears to be a function of metal and sulfuric acid concentrations. Conditions are being sought to give the highest zirconium concentration and the lowest acid concentration that can be used as a feed material for commercial scale-up in the continuous annular chromatographic (CAC) unit without formation of the polymer.

  4. Optimization of Alkaline and Dilute Acid Pretreatment of Agave Bagasse by Response Surface Methodology.

    PubMed

    Ávila-Lara, Abimael I; Camberos-Flores, Jesus N; Mendoza-Pérez, Jorge A; Messina-Fernández, Sarah R; Saldaña-Duran, Claudia E; Jimenez-Ruiz, Edgar I; Sánchez-Herrera, Leticia M; Pérez-Pimienta, Jose A

    2015-01-01

    Utilization of lignocellulosic materials for the production of value-added chemicals or biofuels generally requires a pretreatment process to overcome the recalcitrance of the plant biomass for further enzymatic hydrolysis and fermentation stages. Two of the most employed pretreatment processes are the ones that used dilute acid (DA) and alkaline (AL) catalyst providing specific effects on the physicochemical structure of the biomass, such as high xylan and lignin removal for DA and AL, respectively. Another important effect that need to be studied is the use of a high solids pretreatment (≥15%) since offers many advantaged over lower solids loadings, including increased sugar and ethanol concentrations (in combination with a high solids saccharification), which will be reflected in lower capital costs; however, this data is currently limited. In this study, several variables, such as catalyst loading, retention time, and solids loading, were studied using response surface methodology (RSM) based on a factorial central composite design of DA and AL pretreatment on agave bagasse using a range of solids from 3 to 30% (w/w) to obtain optimal process conditions for each pretreatment. Subsequently enzymatic hydrolysis was performed using Novozymes Cellic CTec2 and HTec2 presented as total reducing sugar (TRS) yield. Pretreated biomass was characterized by wet-chemistry techniques and selected samples were analyzed by calorimetric techniques, and scanning electron/confocal fluorescent microscopy. RSM was also used to optimize the pretreatment conditions for maximum TRS yield. The optimum conditions were determined for AL pretreatment: 1.87% NaOH concentration, 50.3 min and 13.1% solids loading, whereas DA pretreatment: 2.1% acid concentration, 33.8 min and 8.5% solids loading.

  5. Optimization of Alkaline and Dilute Acid Pretreatment of Agave Bagasse by Response Surface Methodology

    PubMed Central

    Ávila-Lara, Abimael I.; Camberos-Flores, Jesus N.; Mendoza-Pérez, Jorge A.; Messina-Fernández, Sarah R.; Saldaña-Duran, Claudia E.; Jimenez-Ruiz, Edgar I.; Sánchez-Herrera, Leticia M.; Pérez-Pimienta, Jose A.

    2015-01-01

    Utilization of lignocellulosic materials for the production of value-added chemicals or biofuels generally requires a pretreatment process to overcome the recalcitrance of the plant biomass for further enzymatic hydrolysis and fermentation stages. Two of the most employed pretreatment processes are the ones that used dilute acid (DA) and alkaline (AL) catalyst providing specific effects on the physicochemical structure of the biomass, such as high xylan and lignin removal for DA and AL, respectively. Another important effect that need to be studied is the use of a high solids pretreatment (≥15%) since offers many advantaged over lower solids loadings, including increased sugar and ethanol concentrations (in combination with a high solids saccharification), which will be reflected in lower capital costs; however, this data is currently limited. In this study, several variables, such as catalyst loading, retention time, and solids loading, were studied using response surface methodology (RSM) based on a factorial central composite design of DA and AL pretreatment on agave bagasse using a range of solids from 3 to 30% (w/w) to obtain optimal process conditions for each pretreatment. Subsequently enzymatic hydrolysis was performed using Novozymes Cellic CTec2 and HTec2 presented as total reducing sugar (TRS) yield. Pretreated biomass was characterized by wet-chemistry techniques and selected samples were analyzed by calorimetric techniques, and scanning electron/confocal fluorescent microscopy. RSM was also used to optimize the pretreatment conditions for maximum TRS yield. The optimum conditions were determined for AL pretreatment: 1.87% NaOH concentration, 50.3 min and 13.1% solids loading, whereas DA pretreatment: 2.1% acid concentration, 33.8 min and 8.5% solids loading. PMID:26442260

  6. Effects of ageing on the content in sulfur-containing amino acids in rat brain.

    PubMed

    Benedetti, M S; Russo, A; Marrari, P; Dostert, P

    1991-01-01

    Concentrations of the sulfur-containing amino acids methionine, homocysteic acid, cysteic acid and taurine were measured in brain structures of young and old Wistar rats in an attempt to establish a possible link between the increase in oxidative stress with ageing and changes in tissue levels of these amino acids. Contrary to data reported by others, in all brain structures of young and old rats homocysteic acid levels could not be quantified. Compared with young rats, in old animals taurine and methionine concentrations significantly decreased in striatum and cortex; decreased taurine levels were also found in nucleus accumbens and cerebellum and lower concentrations of methionine were found in midbrain, hippocampus and pons-medulla. Cysteic acid levels either did not change or significantly increased in cortex and hippocampus. These results are discussed taking into account the biosynthesis of sulfur-containing amino acids in rat brain and the decrease in glutathione in relation to oxidative stress with ageing. Changes in aspartic acid, glutamic acid, serine, glutamine, glycine and GABA concentrations with ageing were also determined in the same brain structures and were in good agreement with those previously reported (Strolin Benedetti et al., 1990 a, b).

  7. Corrosion abatement in sulfuric acid alkylation unit horizontal contactors

    SciTech Connect

    Schutt, H.U.

    1997-09-01

    The need to increase throughput in alkylation plants has resulted in higher operating temperatures and higher water levels in alkylation acids than projected by design. Combined with higher flow rates, the more severe process environment causes carbon steel to corrode at increased rates. Carbon steel is the main material of construction for horizontal contactors (Stratco reactors). A leak to the atmosphere in the hydraulic end cone of one contactor and the realization that basic corrosion data are not available for high throughput process conditions in alkylation units prompted a laboratory study to develop the lacking expertise. Corrosion in alkylation unit horizontal contactors is successfully mitigated by saturating fresh alkylation acid with ferrous sulfate.

  8. Effects of dilute acid pretreatment conditions on enzymatic hydrolysis monomer and oligomer sugar yields for aspen, balsam, and switchgrass.

    PubMed

    Jensen, Jill R; Morinelly, Juan E; Gossen, Kelsey R; Brodeur-Campbell, Michael J; Shonnard, David R

    2010-04-01

    The effects of dilute acid hydrolysis conditions were investigated on total sugar (glucose and xylose) yields after enzymatic hydrolysis with additional analyses on glucose and xylose monomer and oligomer yields from the individual hydrolysis steps for aspen (a hardwood), balsam (a softwood), and switchgrass (a herbaceous energy crop). The results of this study, in the form of measured versus theoretical yields and a severity analysis, show that for aspen and balsam, high dilute acid hydrolysis xylose yields were obtainable at all acid concentrations (0.25-0.75 wt.%) and temperatures (150-175 degrees C) studied as long as reaction time was optimized. Switchgrass shows a relatively stronger dependence on dilute acid hydrolysis acid concentration due to its higher neutralizing mineral content. Maximum total sugar (xylose and glucose; monomer plus oligomer) yields post-enzymatic hydrolysis for aspen, balsam, and switchgrass, were 88.3%, 21.2%, and 97.6%, respectively. In general, highest yields of total sugars (xylose and glucose; monomer plus oligomer) were achieved at combined severity parameter values (log CS) between 2.20 and 2.40 for the biomass species studied.

  9. Exploration of Sulfur Assimilation of Aspergillus fumigatus Reveals Biosynthesis of Sulfur-Containing Amino Acids as a Virulence Determinant

    PubMed Central

    Dümig, Michaela; O'Keeffe, Gráinne; Binder, Jasmin; Doyle, Sean; Beilhack, Andreas

    2016-01-01

    Fungal infections are of major relevance due to the increased numbers of immunocompromised patients, frequently delayed diagnosis, and limited therapeutics. To date, the growth and nutritional requirements of fungi during infection, which are relevant for invasion of the host, are poorly understood. This is particularly true for invasive pulmonary aspergillosis, as so far, sources of (macro)elements that are exploited during infection have been identified to only a limited extent. Here, we have investigated sulfur (S) utilization by the human-pathogenic mold Aspergillus fumigatus during invasive growth. Our data reveal that inorganic S compounds or taurine is unlikely to serve as an S source during invasive pulmonary aspergillosis since a sulfate transporter mutant strain and a sulfite reductase mutant strain are fully virulent. In contrast, the S-containing amino acid cysteine is limiting for fungal growth, as proven by the reduced virulence of a cysteine auxotroph. Moreover, phenotypic characterization of this strain further revealed the robustness of the subordinate glutathione redox system. Interestingly, we demonstrate that methionine synthase is essential for A. fumigatus virulence, defining the biosynthetic route of this proteinogenic amino acid as a potential antifungal target. In conclusion, we provide novel insights into the nutritional requirements of A. fumigatus during pathogenesis, a prerequisite to understanding and fighting infection. PMID:26787716

  10. Performance of a pilot-scale wet electrostatic precipitator for the control of sulfuric acid mist.

    PubMed

    Huang, Jiayu; Wang, Hongmei; Shi, Yingjie; Zhang, Fan; Dang, Xiaoqing; Zhang, Hui; Shu, Yun; Deng, Shuang; Liu, Yu

    2016-10-01

    The use of a wet electrostatic precipitator (WESP) is often regarded as a viable option to reduce sulfuric acid mist emitted from the wet flue gas desulfurization (WFGD) tower in coal-fired power plants. In this study, a pilot-scale wet electrostatic precipitator equipped with a wall-cooled collection electrode is investigated for the control of sulfuric acid mist from a simulated WFGD system. The results show that due to partial charging effect, the removal efficiency of sulfuric acid aerosol decreases when the aerosol size decreases to several tens of nanometers. Moreover, due to the plasma-induced effect, a large number of ultrafine sulfuric acid aerosols below 50 nm formed at a voltage higher than 24 kV inside the WESP. The percentages of submicron-sized aerosols significantly increase together with the voltage. To minimize the adverse plasma-induced effect, a WESP should be operated at a high gas velocity with an optimum high voltage. Even at a high flue gas velocity of 2.3 m s(-1), the mass concentration and the total number concentration of uncaptured sulfuric acid aerosols at the WESP outlet are as low as ca. 0.6 mg m(-3) and ca. 10(4) 1 cm(-3) at 28 kV, respectively. The corresponding removal efficiencies were respectively higher than 99.4 and 99.9 % and are very similar to that at 1.1 and 1.6 m s(-1). Moreover, the condensation-induced aerosol growth enhances the removal of sulfuric acid mist inside a WESP and enables a low emission concentration of ca. 0.65 mg m(-3) with a corresponding removal efficiency superior to 99.4 % even at a low voltage of 21 kV, and of ca. 0.35 mg m(-3) with a corresponding removal efficiency superior to 99.6 % at a higher voltage level of 26 kV.

  11. Role of sulfur-reducing bacteria in a wetland system treating acid mine drainage.

    PubMed

    Riefler, R Guy; Krohn, Jeremy; Stuart, Ben; Socotch, Cheryl

    2008-05-15

    This report describes a twenty month case study of a successive alkalinity producing system (SAPS) treating a strong acid mine drainage (AMD) source in Coshocton County, Ohio. Prior to the commencement of the project, a large volume of black amorphous sludge had accumulated in several of the constructed wetlands. The sludge was found to be 43% organic, with very high concentrations of sulfur, iron, aluminum, and acidity. Based on several biological, physical, and chemical analyses, the sludge was determined to be an anaerobic biofilm with a large population of sulfur-reducing bacteria and a high mineral content due to the formation of iron sulfide and aluminum precipitates. On average the system performed well, generating 26 kg CaCO3/d of alkalinity and capturing 5.0 kg/d of iron and 1.7 kg/d of aluminum. Several simple performance analysis tools were presented in this work. By comparing the pollutant influent and effluent loading, it was determined that the SAPS was performing at capacity and over the past year increased effluent concentrations were due to increased influent loadings and not system deterioration. Further, by performing a detailed cell-by-cell loading analysis of multiple chemical components, the alkalinity generated by limestone dissolution and by sulfate reduction was determined. Interestingly, 61% of the alkalinity generation in the vertical flow wetlands was due to sulfur-reducing bacteria activity, indicating that sulfur-reducing bacteria may play a more significant role in SAPS than expected.

  12. 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.

  13. Corrosion abatement in sulfuric acid alkylation unit horizontal contactors

    SciTech Connect

    Schutt, H.U.

    1999-03-01

    A leak to the atmosphere in the hydraulic end cone of a horizontal contactor and the realization that basic corrosion data are not available for high-throughput process conditions in alkylation units prompted a laboratory study to develop the lacking expertise. Corrosion in the horizontal contractor of an alkylation unit was mitigated successfully by saturating fresh alkylation acid with ferrous sulfate (FeSO{sub 4}).

  14. Using heat pipe to make isotherm condition in catalytic converters of sulfuric acid plants

    NASA Astrophysics Data System (ADS)

    Yousefi, M.; Pahlavanzadeh, H.; Sadrameli, S. M.

    2017-03-01

    In this study, for the first time, it is tried to construct a pilot reactor, for surveying the possibility of creating isothermal condition in the catalytic convertors where SO2 is converted to SO3 in the sulfuric acid plants by heat pipe. The thermodynamic and thermo-kinetic conditions were considered the same as the sulfuric acid plants converters. Also, influence of SO2 gas flow rate on isothermal condition, has been studied. A thermo-siphon type heat pipe contains the sulfur + 5% iodine as working fluid, was used for disposing the heat of reaction from catalytic bed. Our results show that due to very high energy-efficiency, isothermal and passive heat transfer mechanism of heat pipe, it is possible to reach more than 95% conversion in one isothermal catalytic bed. As the results, heat pipe can be used as a certain piece of equipment to create isothermal condition in catalytic convertors of sulphuric acid plants. With this work a major evaluation in design of sulphuric acid plants can be taken place.

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

    SciTech Connect

    Soleimani, Sahar Isgor, O. Burkan Ormeci, Banu

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α 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 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α 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 DH5α 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.

  16. Sulfuric acid baking and leaching of spent Co-Mo/Al2O3 catalyst.

    PubMed

    Kim, Hong-In; Park, Kyung-Ho; Mishra, Devabrata

    2009-07-30

    Dissolution of metals from a pre-oxidized refinery plant spent Co-Mo/Al(2)O(3) catalyst have been tried through low temperature (200-450 degrees C) sulfuric acid baking followed by mild leaching process. Direct sulfuric acid leaching of the same sample, resulted poor Al and Mo recoveries, whereas leaching after sulfuric acid baking significantly improved the recoveries of above two metals. The pre-oxidized spent catalyst, obtained from a Korean refinery plant found to contain 40% Al, 9.92% Mo, 2.28% Co, 2.5% C and trace amount of other elements such as Fe, Ni, S and P. XRD results indicated the host matrix to be poorly crystalline gamma- Al(2)O(3). The effect of various baking parameters such as catalyst-to-acid ratio, baking temperature and baking time on percentage dissolutions of metals has been studied. It was observed that, metals dissolution increases with increase in the baking temperature up to 300 degrees C, then decreases with further increase in the baking temperature. Under optimum baking condition more than 90% Co and Mo, and 93% Al could be dissolved from the spent catalyst with the following leaching condition: H(2)SO(4)=2% (v/v), temperature=95 degrees C, time=60 min and Pulp density=5%.

  17. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

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

    PubMed

    Dugan, P R

    1987-01-01

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

  19. Corn stover saccharification with concentrated sulfuric acid: effects of saccharification conditions on sugar recovery and by-product generation.

    PubMed

    Liu, Ze-Shen; Wu, Xiao-Lei; Kida, Kenji; Tang, Yue-Qin

    2012-09-01

    Although concentrated sulfuric acid saccharification is not a novel method for breaking down lignocellulosic biomass, the process by which saccharification affects biomass decomposition, sugar recovery, and by-product generation is not well studied. The present study employed Taguchi experimental design to study the effects of seven parameters on corn stover concentrated sulfuric acid saccharification. The concentration of sulfuric acid and the temperature of solubilization significantly affect corn stover decomposition. They also have significant effects on glucose and xylose recoveries. Low generation of furfural and 5-hydroxymethyl-2-furfural (5HMF) was noted and organic acids were the main by-products detected in the hydrolysate. Temperature also significantly affected the generation of levulinic acid and formic acid; however, acetic acid generation was not significantly influenced by all seven parameters. The ratio of acid to feedstock significantly affected glucose recovery, but not total sugar recovery. The corn stover hydrolysate was well fermented by both glucose- and xylose-fermenting yeast strains.

  20. Is demineralization with dilute hydrofluoric acid a viable method for isolating mineral stabilized soil organic matter?

    NASA Astrophysics Data System (ADS)

    Sanderman, J.; Baldock, J.; Farrell, M.; Macreadie, P.; McGowan, J.

    2015-12-01

    While you might not be able to dispose of a body with hydrofluoric acid (HF), as fans of Breaking Bad know HF will break silicon-oxygen bonds. These dual properties make HF a powerful tool in investigations of soil organic matter (SOM). When a soil sample is treated with HF, any low molecular weight OM that was bound to mineral surfaces will be released into solution allowing study of the amount and composition of this stable SOM pool. In the work presented here, we take advantage of this property of HF to explore if different forms of SOM are becoming stabilized to mineral surfaces in terrestrial and marine environments. Difference spectra obtained from solid-state 13C NMR spectroscopic analysis of bulk and 10% HF treated soil samples suggest that in aerobic terrestrial environments alkyl-C and aryl-C compounds can dominate the mineral stabilized fraction. However, in anoxic coastal environments this fraction is dominated by O-alkyl C. Demineralization of soil samples with HF is often necessary for removing paramagnetic interferences and concentrating carbon prior to obtaining NMR spectra. The working assumption using dilute HF is that the resultant SOM chemistry determined by NMR spectroscopy has not been significantly biased by the HF treatment process. This assumption has been validated in several studies but also refuted in others. A second goal of this study was to revisit this critical assumption by looking at carbon loss and resulting 13C NMR chemistry from a diverse set of soils and organic materials using HF in 2% and 10% concentrations. We found that 10% HF resulted in slightly greater loss of C than 2% HF but in cases where a preferential shift in chemistry was observed it was observed in both the 2% and 10% treatments. The implications of both of these findings will be discussed in the context of understanding the sources, stability and potential loss mechanisms of mineral stabilized SOM.

  1. Co-oxidation of the sulfur-containing amino acids in an autoxidizing lipid system

    USGS Publications Warehouse

    Wedemeyer, G.A.; Dollar, A.M.

    1963-01-01

    Oxidation of the sulfur amino acids by autoxidizing lipids was studied in a model system consisting of an amino acid dispersed in cold-pressed, molecularly distilled menhaden oil (20–80% w/w). Under all conditions investigated, cysteine was oxidized completely to cystine. Preliminary results suggest that at 110°C the oxidation follows first-order kinetics for at least the first 8 hr. A specific reaction rate constant of 0.25 per hour was calculated. When fatty acids were added to the system, cystine was oxidized to its thiosulfinate ester. When the fatty acid-cystine ratio was 1:2, oxidation of cystine was a maximum. No oxidation of cystine occurred unless either a fatty acid, volatile organic acid, or ethanol was added. Under the conditions investigated, methionine was not oxidized to either its sulfoxide or its sulfone.

  2. 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.

  3. Sulphur Kβ emission spectra reveal protonation states of aqueous sulfuric acid

    PubMed Central

    Niskanen, Johannes; Sahle, Christoph J.; Ruotsalainen, Kari O.; Müller, Harald; Kavčič, Matjaž; Žitnik, Matjaž; Bučar, Klemen; Petric, Marko; Hakala, Mikko; Huotari, Simo

    2016-01-01

    In this paper we report an X-ray emission study of bulk aqueous sulfuric acid. Throughout the range of molarities from 1 M to 18 M the sulfur Kβ emission spectra from H2SO4 (aq) depend on the molar fractions and related deprotonation of H2SO4. We compare the experimental results with results from emission spectrum calculations based on atomic structures of single molecules and structures from ab initio molecular dynamics simulations. We show that the S Kβ emission spectrum is a sensitive probe of the protonation state of the acid molecules. Using non-negative matrix factorization we are able to extract the fractions of different protonation states in the spectra, and the results are in good agreement with the simulation for the higher part of the concentration range. PMID:26888159

  4. Alum recovery and wastewater sludge stabilization with sulfuric acid.

    PubMed

    Jiménez, B; Martínez, M; Vaca, M

    2007-01-01

    Coagulation-flocculation is used to remove helminth ova from wastewater intended for agricultural reuse. Nevertheless, it has the drawback of producing a large amount of sludge which together with the chemicals used to treat the wastewater increases the operating cost. This can be overcome by recovering and recycling the aluminium contained in the sludge. This paper presents how an acid recovery process was applied to an Advanced Primary Treatment (APT) sludge to partially treat it and to reduce its quantity. This is a method applied several decades ago in water sludge that has not been used in secondary wastewater sludge to recover aluminium and to inactivate microorganisms. By adding sulphuric acid to a 6%TS sludge, more than 70% of the aluminium added during the coagulation flocculation process was recovered when a pH of 2 was maintained during 30 minutes and at 300 rpm of mixing conditions. This way the sludge was reduced by 45% in volume and by 63% by mass, inactivating 5 logs of faecal coliforms and 68% of helminth ova. Due to the lower alum consumption, the operating cost of the APT is reduced by 3.78 US$/1,000 m(3).

  5. EVALUATING EFFECTS OF NEPTUNIUM ON THE SRS METHOD FOR CONTROLLED POTENTIAL COULOMETRIC ASSAY OF PLUTONIUM IN SULFURIC ACID SUPPORTING ELECTROLYTE

    SciTech Connect

    Holland, M; Sheldon Nichols, S

    2008-05-09

    A study of the impact of neptunium on the coulometric assay of plutonium in dilute sulfuric acid was performed. Weight aliquots of plutonium standard solutions were spiked with purified neptunium solution to evaluate plutonium measurement performance for aliquots with Pu:Np ratios of 50:1, 30:1, 20:1, 15:1, and 10:1. Weight aliquots of the pure plutonium standard solution were measured as controls. Routine plutonium instrument control standards were also measured. The presence of neptunium in plutonium aliquots significantly increases the random uncertainty associated with the plutonium coulometric measurement performed in accordance with ISO12183:2005.7 However, the presence of neptunium does not appear to degrade electrode performance and conditioning as aliquots of pure plutonium that were interspersed during the measurement of the mixed Pu:Np aliquots continued to achieve the historical short-term random uncertainty for the method. Lack of adequate control of the neptunium oxidation state is suspected to be the primary cause of the elevated measurement uncertainty and will be pursued in a future study.

  6. Monitoring urinary metabolites resulting from sulfur mustard exposure in rabbits, using highly sensitive isotope-dilution gas chromatography-mass spectrometry.

    PubMed

    Nie, Zhiyong; Zhang, Yajiao; Chen, Jia; Lin, Ying; Wu, Bidong; Dong, Yuan; Feng, Jianlin; Liu, Qin; Xie, Jianwei

    2014-08-01

    A highly sensitive method for the determination of sulfur mustard (SM) metabolites thiodiglycol (TDG) and thiodiglycol sulfoxide (TDGO) in urine was established and validated using isotope-dilution negative-ion chemical ionization (NICI) gas chromatography-mass spectrometry (GC-MS). TDGO in the samples was reduced with TiCl3, and then determined together with TDG as a single analyte. The sample preparation procedures, including two solid-phase-extraction (SPE) clean-up steps, were optimized to improve the sensitivity of the method. The limits of detection (LOD) for both TDG and TDG plus TDGO (TDG + TDGO) were 0.1 ng mL(-1), and the limits of quantitation (LOQ) for both were 0.3 ng mL(-1). The method was used in a rabbit cutaneous SM exposure model. Domestic rabbits were exposed to neat liquid SM at three dosage levels (0.02, 0.05, and 0.15 LD50), and the urinary excretion of four species of hydrolysis metabolites, namely free TDG, free plus conjugated TDG (total TDG), free TDG + TDGO, and free plus conjugated TDG + TDGO (total TDG + TDGO), was evaluated to investigate the metabolic processes. The total urinary excretion profiles of the metabolites, including the peak time, time window, and dose-response and time-response relationships, were clarified. The results revealed that the concentrations of TDG and TDG + TDGO in the urine increased quickly and then decreased rapidly in the first two days after SM exposure. The cumulative amount of total TDG + TDGO excreted in urine during the first five days accounted for 0.5-1% of the applied dose of SM. It is also concluded that TDG and TDGO in urine existed mainly in free form, the levels of glucuronide and of sulfate conjugates of TDG or TDGO were very low, and most hydrolysis metabolites were present in the oxidized form (TDGO). The study indicates that the abnormal increase of TDG and TDGO excretion levels can be used as a diagnostic indicator and establishes a reference time-window for retrospective analysis and

  7. Accumulation of intact sulfur mustard in adipose tissue and toxicokinetics by chemical conversion and isotope-dilution liquid chromatography-tandem mass spectrometry.

    PubMed

    Xu, Bin; Zong, Cheng; Zhang, Yajiao; Zhang, Tianhong; Wang, Xiaoying; Qi, Meiling; Wu, Jianfeng; Guo, Lei; Wang, Peng; Chen, Jia; Liu, Qin; Xu, Hua; Xie, Jianwei; Zhang, Zhenqing

    2017-02-01

    Sulfur mustard (SM) is a powerful vesicant and one of the most harmful chemical warfare agents. Although having been studied for a long time, it is still difficult to fully elucidate the mechanisms of SM poisoning, and there is no effective antidote or specific treatment for SM injury. The investigations on toxicokinetics and tissue distribution of SM will help to understand its toxicity and provide a theoretical basis for pretreatment and therapy of SM poisoning. But the metabolic trajectory or fate of intact SM in vivo remains unclear, and there are insufficient experimental data to elucidate, due to its high reactivity and difficulty in biomedical sample analysis. In this paper, a sensitive method for the detection and quantification of intact SM in blood or tissues using isotope-dilution LC-MS/MS coupled with chemical conversion was developed. By transforming highly reactive SM into stable derivative product, the real concentration of intact SM in biological samples was obtained accurately. The toxicokinetics and tissue distribution studies of intact SM in rats were successfully profiled by the novel method after intravenous (10 mg/kg) or cutaneous administration (1, 3 and 10 mg/kg). The SM level in blood with peak time at 30-60 min determined in cutaneous exposure experiment was found much higher than previously reported, and the mean residence time in blood extended to 1-1.5 h. A significant accumulation of intact SM was observed in adipose tissues, including the perirenal fat, epididymal fat, subcutaneous fat and brown fat, in which the concentrations of SM were at least 15 times greater than those in non-adipose tissues in cutaneous exposed rats. The recovery of SM in body fat was calculated as 3.3 % of bioavailable SM (the bioavailability after cutaneous exposure was evaluated as 16 %). Thus, the adipose tissue was important for SM distribution and toxicity, which may pioneer a new model for both the prevention and treatment of SM exposure.

  8. Stochastic analysis of current fluctuations during general corrosion of stainless steel in sulfuric acid

    SciTech Connect

    Petek, A.; Dolecek, V.; Vlachy, V.

    1997-12-01

    Current fluctuations during general corrosion of stainless steel in sulfuric acid were studied experimentally and analyzed using a simple electrochemical model. Stochastic behavior of the metal-electrolyte interface in the model was based upon the assumption that elementary fluctuation sources were related to fluxes of electrons that pass from a metal to electron-acceptor ions in solution. The number of successful electron transfers obeyed a Gaussian distribution, from which the corrosion current density and transfer coefficients could be determined.

  9. Pretreatment of Human Epidermal Keratinocytes In Vitro With Ethacrynic Acid Reduces Sulfur Mustard Cytotoxicity

    DTIC Science & Technology

    2004-01-01

    estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the...display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES...Ethacrynic Acid Reduces 5b. GRANT NUMBER Sulfur Mustard Toxicity 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Gross, CL, Nipwoda, MT, Nealley

  10. 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.

  11. 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.

  12. The dynamics of sorption of sulfuric acid by weakly basic polyacrylic anion exchangers

    NASA Astrophysics Data System (ADS)

    Mamchenko, A. V.; Kushnir, T. V.

    2009-05-01

    The nonequilibrium dynamics of sorption of sulfuric acid by free base forms of Amberlite IRA-67 and Lewatite VP.OC.1072 weakly basic anion exchangers is studied. It is established that, in hydrodynamic regimes of filtration, which are typical of OH filters of the first stage of water-desalting plants, the limiting stage of sorption kinetics is inside diffusion. It is concluded that the process is correctly described by an asymptotic solution to the inside-diffusion model of sorption dynamics.

  13. Formation and growth of molecular clusters containing sulfuric acid, water, ammonia, and dimethylamine.

    PubMed

    DePalma, Joseph W; Doren, Douglas J; Johnston, Murray V

    2014-07-24

    The structures and thermochemistry of molecular clusters containing sulfuric acid, water, ammonia, and/or dimethylamine ((CH3)2NH or DMA) are explored using a combination of Monte Carlo configuration sampling, semiempirical calculations, and density functional theory (DFT) calculations. Clusters are of the general form [(BH(+))n(HSO4(-))n(H2O)y], where B = NH3 or DMA, 2 ≤ n ≤ 8, and 0 ≤ y ≤ 10. Cluster formulas are written based on the computed structures, which uniformly show proton transfer from each sulfuric acid molecule to a base molecule while the water molecules remain un-ionized. Cluster formation is energetically favorable, owing to strong electrostatic attraction among the ions. Water has a minor effect on the energetics of cluster formation, lowering the free energy of formation by ∼ 10% depending on the cluster size and number of water molecules. Cluster growth (addition of one base molecule and one sulfuric acid molecule to a pre-existing cluster) and base substitution (substituting DMA for ammonia) are also energetically favorable processes for both anhydrous and hydrated clusters. However, the effect of water is different for different bases. Hydrated ammonium bisulfate clusters have a more favorable free energy for growth (i.e., incrementing n with fixed y) than anhydrous clusters, while the reverse is observed for dimethylammonium bisulfate clusters, where the free energy for growth is more favorable for anhydrous clusters. The substitution of DMA for ammonia in bisulfate clusters is favorable but exhibits a complex water dependence. Base substitution in smaller bisulfate clusters is enhanced by the presence of water, while base substitution in larger bisulfate clusters is less favorable for hydrated clusters than that for anhydrous clusters. While DMA substitution can stabilize small clusters containing one or a few sulfuric acid molecules, the free energy advantage of forming amine clusters relative to ammonia clusters becomes less

  14. Combined Dilute Acid and Solvent Based Pretreatment of Agricultural Wastes for Efficient Lignocellulosic Fractionation and Biofuels Production

    SciTech Connect

    Brodeur, G.; Ramakrishnan, S.; Wilson, C.; Telotte, J.; Collier, J.; Stickel, J.

    2013-01-01

    A true biorefinery for processing lignocellulosic biomass should achieve maximum utilization of all major constituents (cellulose, hemicellulose, & lignin) within the feedstock. In this work a combined pretreatment process of dilute acid (DA) and N-methyl morpholine N-oxide (NMMO) is described that allows for both fractionation and subsequent complete hydrolysis of the feedstocks (corn stover and sugarcane bagasse). During this multi-step processing, the dilute acid pretreatment solubilizes the majority (>90%) of the hemicellulosic fraction, while the NMMO treatment yields a cellulosic fraction that is completely digestible within 48 hours at low enzyme loadings. With both the cellulosic and hemicellulosic fractions being converted into separate, dissolved sugar fractions, the remaining portion is nearly pure lignin. When used independently, DA and NMMO pretreatments are only able to achieve ~80% and ~45% cellulosic conversion, respectively. Mass balance calculations along with experimental results are used to illustrate the feasibility of separation and recycling of NMMO.

  15. Structural features of dilute acid, steam exploded, and alkali pretreated mustard stalk and their impact on enzymatic hydrolysis.

    PubMed

    Kapoor, Manali; Raj, Tirath; Vijayaraj, M; Chopra, Anju; Gupta, Ravi P; Tuli, Deepak K; Kumar, Ravindra

    2015-06-25

    To overcome the recalcitrant nature of biomass several pretreatment methodologies have been explored to make it amenable to enzymatic hydrolysis. These methodologies alter cell wall structure primarily by removing/altering hemicelluloses and lignin. In this work, alkali, dilute acid, steam explosion pretreatment are systematically studied for mustard stalk. To assess the structural variability after pretreatment, chemical analysis, surface area, crystallinity index, accessibility of cellulose, FT-IR and thermal analysis are conducted. Although the extent of enzymatic hydrolysis varies upon the methodologies used, nevertheless, cellulose conversion increases from <10% to 81% after pretreatment. Glucose yield at 2 and 72h are well correlated with surface area and maximum adsorption capacity. However, no such relationship is observed for xylose yield. Mass balance of the process is also studied. Dilute acid pretreatment is the best methodology in terms of maximum sugar yield at lower enzyme loading.

  16. 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.

  17. Numerical Simulation of Condensation of Sulfuric Acid and Water in a Large Two-stroke Marine Diesel Engine

    NASA Astrophysics Data System (ADS)

    Walther, J. H.; Karvounis, N.; Pang, K. M.

    2016-11-01

    We present results from computational fluid dynamics simulations of the condensation of sulfuric acid (H2SO 4) and water (H2 O) in a large two-stroke marine diesel engine. The model uses a reduced n-heptane skeletal chemical mechanism coupled with a sulfur subset to simulate the combustion process and the formation of SOx and H2SO 4 . Condensation is modeled using a fluid film model coupled with the Eulerian in-cylinder gas phase. The fluid film condensation model is validated against both experimental and numerical results. The engine simulations reveal that the fluid film has a significant effect on the sulfuric acid gas phase. A linear correlation is found between the fuel sulfur content and the sulfuric acid condensation rate. The initial in-cylinder water content is found not to affect the sulfuric acid condensation but it has a high impact on water condensation. The scavenging pressure level shows an inverse correlation between pressure and condensation rate due to change in the flame propagation speed. Finally, increasing the cylinder liner temperature significantly decreases water condensation but has a negligible influence on the condensation of sulfuric acid.

  18. Sulfuric acid-induced changes in the physiology and structure of the tracheobronchial airways

    SciTech Connect

    Gearhart, J.M.; Schlesinger, R.B.

    1989-02-01

    Sulfuric acid aerosols occur in the ambient particulate mode due to atmospheric conversion from sulfur dioxide (SO2). This paper describes the response of the rabbit tracheobronchial tree to daily exposures to sulfuric acid (H2SO4) aerosol, relating physiological and morphological parameters. Rabbits were exposed to filtered air (sham control) or to submicrometer-sized H2SO4 at 250 micrograms/m3 H2SO4, for 1 hr/day, 5 days/week, with sacrifices after 4, 8, and 12 months of acid (or sham) exposure; some rabbits were allowed a 3-month recovery after all exposures ended. H2SO4 produced a slowing of tracheobronchial mucociliary clearance during the first weeks of exposure; this change became significantly greater with continued exposures and did not improve after exposures ended. Airway hyperresponsiveness was evident by 4 months of acid exposure; the condition worsened by 8 months of exposure and appeared to stabilize after this time. Standard pulmonary mechanics parameters showed no significant trends with repeated acid exposure, except for a decline in dynamic lung compliance in animals exposed to acid for 12 months. Lung tissue samples obtained from exposed animals showed a shift toward a greater frequency of smaller airways compared to control, an increase in epithelial secretory cell density in smaller airways, and a shift from neutral to acidic glycoproteins in the secretory cells. The effect on airway diameter resolved after the exposures ceased, but the secretory cell response did not return to normal within the recovery period. No evidence of inflammatory cell infiltration was found due to H2SO4 exposure. Thus, significant alterations in the physiology of the tracheobronchial tree have been demonstrated due to repeated 1-hr exposures to a concentration of H2SO4 that is one-fourth the current 8-hr threshold limit value for exposure in the work environment.

  19. Heterogeneous interactions of chlorine nitrate, hydrogen chloride, and nitric acid with sulfuric acid surfaces at stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

    1988-01-01

    The heterogeneous interactions of ClONO2, HCl, and HNO3 with sulfuric acid surfaces were studied using a Knudsen cell flow reactor. The surfaces studied, chosen to simulate global stratospheric particulate, were composed of 65-75 percent H2SO4 solutions at temperatures in the range -63 to -43 C. Heterogeneous loss, but not reaction, of HNO3 and HCl occurred on these surfaces; the measured sticking coefficients are reported. Chlorine nitrate reacted on the cold sulfuric acid surfaces, producing gas-phase HOCl and condensed HNO3. CLONO2 also reacted with HCl dissolved in the 65-percent H2SO4 solution at -63 C, forming gaseous Cl2. In all cases studied, the sticking and/or reaction coefficients were much larger for the 65-percent H2SO4 solution at -63 C than for the 75-percent solution at -43 C.

  20. Sulfur amino acid metabolism limits the growth of children living in environments of poor sanitation.

    PubMed

    Bickler, Stephen W; Ring, Jason; De Maio, Antonio

    2011-09-01

    Environmental enteropathy has been identified as a cause of poor growth in children living in low-income countries, but a mechanism has not been well defined. We suggest changes in sulfur amino acid metabolism can in part explain the poor growth and possibly the histological changes in the small bowel, which is the hallmark of environmental enteropathy. In environments of poor sanitation, where infection is common, we propose increased oxidative stress drives methionine metabolism toward cystathionine synthesis. This "cystathionine siphon" limits sulfur amino acids from participating in critical protein synthesis pathways. Increased expression of cystathionine β-synthase (CBS) could be one mechanism, as lipopolysaccharide and TNFα increase activity of this enzyme in vivo. CBS catalyzes the first of two steps in the transsulfuration pathway that converts homocysteine to cysteine. As enterocytes are one of the most rapidly proliferating cells in the body, we suggest diminished translation might also be important in the barrier failure observed in environmental enteropathy. Identifying sulfur amino acid metabolism as a mechanism leading to poor growth provides a new testable hypothesis for the undernutrition observed in children living in settings of poor sanitation.

  1. 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, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P.; Rondo, Linda; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S.; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M.; Worsnop, Douglas R.

    2013-01-01

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

  2. Calibration of a chemical ionization mass spectrometer for the measurement of gaseous sulfuric acid.

    PubMed

    Kürten, Andreas; Rondo, Linda; Ehrhart, Sebastian; Curtius, Joachim

    2012-06-21

    The accurate measurement of the gaseous sulfuric acid concentration is crucial within many fields of atmospheric science. Instruments utilizing chemical ionization mass spectrometry (CIMS) measuring H(2)SO(4), therefore, require a careful calibration. We have set up a calibration source that can provide a stable and adjustable concentration of H(2)SO(4). The calibration system initiates the production of sulfuric acid through the oxidation of SO(2) by OH. The hydroxyl radical is produced by UV photolysis of water vapor. A numerical model calculates the H(2)SO(4) concentration provided at the outlet of the calibration source. From comparison of this concentration and the signals measured by CIMS, a calibration factor is derived. This factor is evaluated to be 1.1 × 10(10) cm(-3), which is in good agreement with values found in the literature for other CIMS instruments measuring H(2)SO(4). The calibration system is described in detail and the results are discussed. Because the setup is external to the CIMS instrument, it offers the possibility for future CIMS intercomparison measurements by providing defined and stable concentrations of sulfuric acid.

  3. Thoracic Duct Chylous Fistula Following Severe Electric Injury Combined with Sulfuric Acid Burns: A Case Report.

    PubMed

    Chang, Fei; Cheng, Dasheng; Qian, Mingyuan; Lu, Wei; Li, Huatao; Tang, Hongtai; Xia, Zhaofan

    2016-10-11

    BACKGROUND As patients with thoracic duct injuries often suffer from severe local soft tissue defects, integrated surgical treatment is needed to achieve damage repair and wound closure. However, thoracic duct chylous fistula is rare in burn patients, although it typically involves severe soft tissue damage in the neck or chest. CASE REPORT A 32-year-old male patient fell after accidentally contacting an electric current (380 V) and knocked over a barrel of sulfuric acid. The sulfuric acid continuously poured onto his left neck and chest, causing combined electrical and sulfuric acid burn injuries to his anterior and posterior torso, and various parts of his limbs (25% of his total body surface area). During treatment, chylous fistula developed in the left clavicular region, which we diagnosed as thoracic duct chylous fistula. We used diet control, intravenous nutritional support, and continuous somatostatin to reduce the chylous fistula output, and hydrophilic silver ion-containing dressings for wound coverage. A boneless muscle flap was used to seal the left clavicular cavity, and, integrated, these led to resolution of the chylous fistula. CONCLUSIONS Patients with severe electric or chemical burns in the neck or chest may be complicated with thoracic duct injuries. Although conservative treatment can control chylous fistula, wound cavity filling using a muscle flap is an effective approach for wound healing.

  4. A hybrid Li-air battery with buckypaper air cathode and sulfuric acid electrolyte

    SciTech Connect

    Li, YF; Huang, K; Xing, YC

    2012-10-30

    We demonstrate a type of carbon nanotube based buckypaper cathode in a hybrid electrolyte Li-air battery (HyLAB) that showed outstanding discharging performances. The HyLAB has sulfuric acid as the catholyte and a large active electrode area (10 cm(2)). The active cathode layer was made from a buckypaper with 5 wt.% Pt supported on carbon nanotubes (Pt/CNTs) for oxygen reduction and evolution. A similar cathode was constructed with a catalyst of 5 wt.% Pt supported on carbon black (Pt/CB). It is demonstrated that sulfuric acid can achieve high discharging current densities while maintaining relatively high cell potentials. The cell with Pt/CNTs showed a much better performance than with Pt/CB at high current densities. The HyLAB with Pt/CNTs achieved a discharging capacity of 306 mAh/g and a cell voltage of 3.15 V at 0.2 mA/cm(2). The corresponding specific energy is 1067 Wh/kg based on the total weight of the sulfuric acid. Slow decrease in performance was observed, but it can be recovered by refilling the cell with new electrolyte after continuous discharging of more than 75 h. A charge-discharge experiment at 0.2 mA/cm(2) showed that the cell was rechargeable with a capacity of more than 300 mAh/g. (c) 2012 Elsevier Ltd. All rights reserved.

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

    PubMed

    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, João; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Kürten, Andreas; Kurtén, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipilä, Mikko; Tomé, António; Tsagkogeorgas, Georgios; Vehkamäki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petäjä, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

    2013-10-22

    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.

  6. Comparison of sulfuric and hydrochloric acids as catalysts in hydrolysis of Kappaphycus alvarezii (cottonii).

    PubMed

    Meinita, Maria Dyah Nur; Hong, Yong-Ki; Jeong, Gwi-Taek

    2012-01-01

    In this study, hydrolysis of marine algal biomass Kappaphhycus alvarezii using two different acid catalysts was examined with the goal of identifying optimal reaction conditions for the formation of sugars and by-products. K. alvarezii were hydrolyzed by autoclave using sulfuric acid or hydrochloric acid as catalyst with different acid concentrations (0.1-1.0 M), substrate concentrations (1.0-13.5%), hydrolysis time (10-90 min) and hydrolysis temperatures (100-130 (°)C). A difference in galactose, glucose, reducing sugar and total sugar content was observed under the different hydrolysis conditions. Different by-product compounds such as 5-hydroxymethylfurfural and levulinic acid were also observed under the different reaction conditions. The optimal conditions for hydrolysis were achieved at a sulfuric acid concentration, temperature and reaction time of 0.2 M, 130 °C and 15 min, respectively. These results may provide useful information for the development of more efficient systems for biofuel production from marine biomass.

  7. Uptake of methacrolein into aqueous solutions of sulfuric acid and hydrogen peroxide.

    PubMed

    Liu, Ze; Wu, Ling-Yan; Wang, Tian-He; Ge, Mao-Fa; Wang, Wei-Gang

    2012-01-12

    Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol (SOA) formation from isoprene and its gas-phase oxidation products, but the kinetics and chemical mechanism remain largely uncertain. Here we report the first measurement of uptake of methacrolein into aqueous solutions of sulfuric acid and hydrogen peroxide in the temperature range of 253-293 K. The steady-state uptake coefficients were acquired and increased quickly with increasing sulfuric acid concentration and decreasing temperature. Propyne, acetone, and 2,3-dihydroxymethacrylic acid were suggested as the products. The chemical mechanism is proposed to be the oxidation of carbonyl group and C═C double bonds by peroxide hydrogen in acidic environment, which could explain the large content of polyhydroxyl compounds in atmospheric fine particles. These results indicate that multiphase acid-catalyzed oxidation of methacrolein by hydrogen peroxide can contribute to SOA mass in the atmosphere, especially in the upper troposphere.

  8. Formaldehyde instrument development and boundary layer sulfuric acid: Implications for photochemistry

    NASA Astrophysics Data System (ADS)

    Case Hanks, Anne Theresa

    This work presents the development of a laser-induced fluorescence technique to measure atmospheric formaldehyde. In conjunction with the technique, the design of a compact, narrow linewidth, etalon-tuned titanium: sapphire laser cavity which is pumped by the second harmonic of a kilohertz Nd:YAG laser is also presented. The fundamental tunable range is from 690-1100 nm depending on mirror reflectivities and optics kit used. The conversion efficiency is at least 25% for the fundamental, and 2-3% for intracavity frequency doubling from 3.5-4W 532 nm pump power. The linewidth is <0.1 cm-1, and the pulsewidth is 18 nsec. Applications of this cavity include the measurement of trace gas species by laser-induced fluorescence, cavity ringdown spectroscopy, and micropulse lidar in the UV-visible region. Also presented are observations of gas-phase sulfuric acid from the NEAQS-ITCT 2K4 (New England Air Quality Study--- Intercontinental Transport and Chemical Transformation) field campaign in July and August 2004. Sulfuric acid values are reported for a polluted environment and possible nucleation events as well as particle growth within the boundary layer are explored. Sulfate production rates via gas phase oxidation of sulfur dioxide are also reported. This analysis allows an important test of our ability to predict sulfuric acid concentration and probe its use as a fast time response photochemical tracer for the hydroxyl radical, OH. In comparison, the NASA time-dependent photochemical box model is used to calculate OH concentration. Nighttime H2SO4 values are examined to test our understanding of nocturnal OH levels and oxidation processes. In comparison, sulfuric acid from a large ground based mission in Tecamac, Mexico (near the northern boundary of Mexico City) during MIRAGE-Mex field campaign (March 2006) is presented. This and other measurements are used to characterize atmospheric oxidation and predict sulfuric acid and OH concentrations at the site. The

  9. Glucose content in the liquid hydrolysate after dilute acid pretreatment is affected by the starch content in rice straw.

    PubMed

    Teramura, Hiroshi; Oshima, Tomoko; Matsuda, Fumio; Sasaki, Kengo; Ogino, Chiaki; Yamasaki, Masanori; Kondo, Akihiko

    2013-12-01

    Lignocellulosic biomass, such as rice straw, is often utilized as a bioresource after being hydrolyzed using dilute acid and separated into liquid hydrolysate and acid-insoluble residue. However, the biomass component that determines the distribution between liquid hydrolysate and acid-insoluble residue has not yet been clarified. In this study, the glucose content in the liquid hydrolysate and weight of acid-insoluble residue of 13 rice cultivars were analyzed. Starch content was positively correlated with glucose content in the liquid hydrolysate, and negatively correlated with acid-insoluble residue weight. These results indicate that the glucose in the liquid hydrolysate is mainly liberated from starch rather than cellulose in the rice straw. These observations suggest that starch content is a good indicator of the glucose distribution between the liquid hydrolysate and insoluble residue.

  10. 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

  11. Oxaldihydroxamic acid as a new reagent for the fixation of atmospheric sulfur dioxide

    NASA Astrophysics Data System (ADS)

    Paul, Khana Rani; Gupta, V. K.

    In the present investigation 0.01 M aqueous oxaldihydroxamic acid has been used to stabilize the atmospheric sulfur dioxide. The collection efficiency of the reagent was found to be ~ 100% and the sulfite solution was stable for ⩾ 30 days at room temperature. The sulfite ion was estimated colorimetrically using acidified p-aminoazobenzene and formaldehyde. The pink coloured dye, λmax 505 nm, obeys Beer's law in the range of 0.1-1 ppm. The procedure has been optimized with respect to the acidity, time and reagent concentration. The method is simple, free from pH dependence and several commonly present air pollutants do not interfere.

  12. Minimizing sulfur contamination and rinse water volume required following a sulfuric acid/hydrogen peroxide clean by performing a chemically basic rinse

    SciTech Connect

    Clews, P.J.; Nelson, G.C.; Resnick, P.J.; Matlock, C.A.; Adkins, C.L.J.

    1997-08-01

    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 wafer surfaces. Various rinsing conditions were tested and the resulting residual contamination on the wafer surface was measured. The addition of small amounts of a chemical base such as ammonium hydroxide to the rinse water has been found to be effective in reducing the surface concentration of sulfur and also mitigates the particle growth that occurs on SPM cleaned wafers. The volume of room temperature water required to rinse these wafers is also significantly reduced.

  13. Effect of pH on sulfite oxidation by Thiobacillus thiooxidans cells with sulfurous acid or sulfur dioxide as a possible substrate.

    PubMed Central

    Takeuchi, T L; Suzuki, I

    1994-01-01

    The oxidation of sulfite by Thiobacillus thiooxidans was studied at various pH values with changing concentrations of potassium sulfite. The optimal pH for sulfite oxidation by cells was a function of sulfite concentrations, rising with increasing substrate concentrations, while that by the cell extracts was unaffected. The sulfite oxidation by cells was inhibited at high sulfite concentrations, particularly at low pH values. The results from kinetic studies show that the fully protonated form of sulfite, sulfurous acid or sulfur dioxide, is the form which penetrates the cells for the oxidation. PMID:8300544

  14. Co-hydrolysis of hydrothermal and dilute acid pretreated populus slurries to support development of a high-throughput pretreatment system

    PubMed Central

    2011-01-01

    Background The BioEnergy Science Center (BESC) developed a high-throughput screening method to rapidly identify low-recalcitrance biomass variants. Because the customary separation and analysis of liquid and solids between pretreatment and enzymatic hydrolysis used in conventional analyses is slow, labor-intensive and very difficult to automate, a streamlined approach we term 'co-hydrolysis' was developed. In this method, the solids and liquid in the pretreated biomass slurry are not separated, but instead hydrolysis is performed by adding enzymes to the whole pretreated slurry. The effects of pretreatment method, severity and solids loading on co-hydrolysis performance were investigated. Results For hydrothermal pretreatment at solids concentrations of 0.5 to 2%, high enzyme protein loadings of about 100 mg/g of substrate (glucan plus xylan) in the original poplar wood achieved glucose and xylose yields for co-hydrolysis that were comparable with those for washed solids. In addition, although poplar wood sugar yields from co-hydrolysis at 2% solids concentrations fell short of those from hydrolysis of washed solids after dilute sulfuric acid pretreatment even at high enzyme loadings, pretreatment at 0.5% solids concentrations resulted in similar yields for all but the lowest enzyme loading. Conclusions Overall, the influence of severity on susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernable, showing co-hydrolysis to be a viable approach for identifying plant-pretreatment-enzyme combinations with substantial advantages for sugar production. PMID:21749707

  15. 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; Drescher, Sadie R; Tuskan, Gerald A; Davis, Dr. Mark F.; Nghiem, Nhuan Phu

    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.

  16. Why sulfuric acid forms particles so extremely well, and how organics might still compete

    NASA Astrophysics Data System (ADS)

    Kurten, T.; Ehn, M.; Kupiainen, O.; Olenius, T.; Rissanen, M.; Thornton, J. A.; Nielsen, L.; Jørgensen, S.; Ortega Colomer, I. K.; Kjaergaard, H. G.; Vehkamäki, H.

    2013-12-01

    It is a well-known result in aerosol science that the single most important molecule for the first steps of new-particle formation in our atmosphere is sulfuric acid, H2SO4. From a chemical perspective, this seems somewhat counterintuitive: the atmosphere contains thousands of different organic compounds, many of which can potentially form oxidation products with even lower volatility than H2SO4. The unique role of sulfuric acid is due to its formation kinetics. The conversion of sulfur dioxide, SO2 to H2SO4 requires only a single oxidant molecule (e.g. OH), as subsequent steps are extremely rapid. Still, the saturation vapor pressure of H2SO4 is over 108 times lower than that of SO2. In contrast, the oxidation reactions of organic molecules typically lower their saturation vapor pressure by only a factor of 10-1000 per oxidation step. Therefore, organic compounds are usually lost to pre-existing aerosol surfaces before they have undergone sufficiently many oxidation reactions to nucleate on their own. The presence of strong nitrogen-containing base molecules such as amines enhances the particle-forming advantages of sulfuric acid even further. Quantum chemical calculations indicate that the evaporation rate of sulfuric acid from key clusters containing two acid molecules may decrease by a factor of 108 in the presence of ppt-level concentrations of amines, implying a total decrease of up to 1016 in the effective vapor pressure going from SO2 to H2SO4. In some circumstances, this decrease causes the energy barrier for new-particle formation to disappear: the process is no longer nucleation, and some common applications of e.g. the nucleation theorem cease to apply. Cluster kinetic models combined with first-principles evaporation rates appear to describe this sulfuric acid - base clustering reasonably well, and result in cluster formation rates close to those measured at the CLOUD experiment in CERN. There may nevertheless exist exceptions to the general rule that

  17. Production of fuel ethanol from bamboo by concentrated sulfuric acid hydrolysis followed by continuous ethanol fermentation.

    PubMed

    Sun, Zhao-Yong; Tang, Yue-Qin; Iwanaga, Tomohiro; Sho, Tomohiro; Kida, Kenji

    2011-12-01

    An efficient process for the production of fuel ethanol from bamboo that consisted of hydrolysis with concentrated sulfuric acid, removal of color compounds, separation of acid and sugar, hydrolysis of oligosaccharides and subsequent continuous ethanol fermentation was developed. The highest sugar recovery efficiency was 81.6% when concentrated sulfuric acid hydrolysis was carried out under the optimum conditions. Continuous separation of acid from the saccharified liquid after removal of color compounds with activated carbon was conducted using an improved simulated moving bed (ISMB) system, and 98.4% of sugar and 90.5% of acid were recovered. After oligosaccharide hydrolysis and pH adjustment, the unsterilized saccharified liquid was subjected to continuous ethanol fermentation using Saccharomycescerevisiae strain KF-7. The ethanol concentration, the fermentation yield based on glucose and the ethanol productivity were approximately 27.2 g/l, 92.0% and 8.2 g/l/h, respectively. These results suggest that the process is effective for production of fuel ethanol from bamboo.

  18. Analysis of the interactions of sulfur-containing amino acids in membrane proteins.

    PubMed

    Gómez-Tamayo, José C; Cordomí, Arnau; Olivella, Mireia; Mayol, Eduardo; Fourmy, Daniel; Pardo, Leonardo

    2016-08-01

    The interactions of Met and Cys with other amino acid side chains have received little attention, in contrast to aromatic-aromatic, aromatic-aliphatic or/and aliphatic-aliphatic interactions. Precisely, these are the only amino acids that contain a sulfur atom, which is highly polarizable and, thus, likely to participate in strong Van der Waals interactions. Analysis of the interactions present in membrane protein crystal structures, together with the characterization of their strength in small-molecule model systems at the ab-initio level, predicts that Met-Met interactions are stronger than Met-Cys ≈ Met-Phe ≈ Cys-Phe interactions, stronger than Phe-Phe ≈ Phe-Leu interactions, stronger than the Met-Leu interaction, and stronger than Leu-Leu ≈ Cys-Leu interactions. These results show that sulfur-containing amino acids form stronger interactions than aromatic or aliphatic amino acids. Thus, these amino acids may provide additional driving forces for maintaining the 3D structure of membrane proteins and may provide functional specificity.

  19. Protein–Protein Interactions in Dilute to Concentrated Solutions: α-Chymotrypsinogen in Acidic Conditions

    PubMed Central

    2015-01-01

    Protein–protein interactions were investigated for α-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 α-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

  20. A comparative study of ethanol production using dilute acid, ionic liquid and AFEX™ pretreated corn stover

    PubMed Central

    2014-01-01

    Background In a biorefinery producing cellulosic biofuels, biomass pretreatment will significantly influence the efficacy of enzymatic hydrolysis and microbial fermentation. Comparison of different biomass pretreatment techniques by studying the impact of pretreatment on downstream operations at industrially relevant conditions and performing comprehensive mass balances will help focus attention on necessary process improvements, and thereby help reduce the cost of biofuel production. Results An on-going collaboration between the three US Department of Energy (DOE) funded bioenergy research centers (Great Lakes Bioenergy Research Center (GLBRC), Joint BioEnergy Institute (JBEI) and BioEnergy Science Center (BESC)) has given us a unique opportunity to compare the performance of three pretreatment processes, notably dilute acid (DA), ionic liquid (IL) and ammonia fiber expansion (AFEXTM), using the same source of corn stover. Separate hydrolysis and fermentation (SHF) was carried out using various combinations of commercially available enzymes and engineered yeast (Saccharomyces cerevisiae 424A) strain. The optimal commercial enzyme combination (Ctec2: Htec2: Multifect Pectinase, percentage total protein loading basis) was evaluated for each pretreatment with a microplate-based assay using milled pretreated solids at 0.2% glucan loading and 15 mg total protein loading/g of glucan. The best enzyme combinations were 67:33:0 for DA, 39:33:28 for IL and 67:17:17 for AFEX. The amounts of sugar (kg) (glucose: xylose: total gluco- and xylo-oligomers) per 100 kg of untreated corn stover produced after 72 hours of 6% glucan loading enzymatic hydrolysis were: DA (25:2:2), IL (31:15:2) and AFEX (26:13:7). Additionally, the amounts of ethanol (kg) produced per 100 kg of untreated corn stover and the respective ethanol metabolic yield (%) achieved with exogenous nutrient supplemented fermentations were: DA (14.0, 92.0%), IL (21.2, 93.0%) and AFEX (20.5, 95.0%), respectively

  1. Detection of dilute organic acids in water by inelastic tunneling spectroscopy

    NASA Technical Reports Server (NTRS)

    Skarlatos, Y.; Barker, R. C.; Haller, G. L.; Yelon, A.

    1974-01-01

    Study of inelastic electron tunneling spectroscopy (IETS) spectra obtained from junctions exposed to dilute solutions of organic molecules in both liquid and vapor phases. The results indicate that it is possible in principle to detect the presence and to measure the concentration of at least some organic molecules in dilute aqueous solution by means of the IETS technique. Some fine points pertaining to the application of this technique are discussed, and it is pointed out that through appropriate refinements IETS may become a valuable tool for analytical water chemistry.

  2. 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.

  3. 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.

  4. Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere - Abundances inferred from observed radio opacity

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.; Eshleman, V. R.

    1982-01-01

    It is suggested that the absorbing characteristics of sulfuric acid vapor appear to reconcile what had been thought to be an inconsistency among measurements and deductions regarding the constituents of the Venus atmosphere and radio occultation, radar reflection, and radio emission measurements of its opacity. Laboratory measurements of sulfuric acid, sulfur dioxide, water vapor, and carbon dioxide are used to model relative contributions to opacity as a function of height in a way that is consistent with observations of the constituents and absorbing properties of the atmosphere. It is concluded that sulfuric acid vapor is likely to be the principal microwave absorber in the 30-50 km altitude range of the middle atmosphere of Venus.

  5. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    SciTech Connect

    Oyaidzu, M.; Isobe, K.; Hayashi, T.

    2015-03-15

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions.

  6. Energy and Angle Resolved Uptake of Organic Gases in Concentrated Sulfuric Acid

    NASA Astrophysics Data System (ADS)

    Fiehrer, Kathleen; Nathanson, Gilbert

    1996-03-01

    We have measured the uptake of reactive gases in concentrated (98.8 wtsulfuric acid at 298 K. Our goal is to determine the fraction of gas molecules that dissolve in and react with concentrated sulfuric acid as a function of impact angle, collision energy, and gas molecule basicity (pKBH+). These gases include olefins, alcohols, ethers, aldehydes, and carboxylic acids. We have investigated how scattering and solvation compete at high and low impact energies and at grazing and perpendicular approach directions. We find that the sticking probability decreases slowly with increasing impact energy and with more grazing angle of incidence. However, the sticking probabilities change dramatically with gas functionality and scale monotonically with the molecule's solution phase basicity. Thus, the sticking probability decreases in the order ethanol, dimethyl ether, formic acid, acetaldehyde, and propene.

  7. Examination of Organic Reactions in UT/LS Aerosols: Temperature Dependence in Sulfuric Acid Solution

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; Michelsen, R. R.

    2004-12-01

    Sulfuric acid has been used for decades as an industrial catalyst for organic reactions, but its parallel role in atmospheric aerosols is relatively unexplored, despite identification of a wide array of organic compounds in particles. Several recent studies have demonstrated possible reactions in acidic particles, generally involving carbonyl groups (C=O) and leading to the formation of larger molecules. Reactions of oxygenated organic compounds in acidic solution are most often studied near room temperature, while the sulfate particles of the upper troposphere and lower stratosphere are significantly colder. Our studies of ethanal (acetaldehyde) suggest that reactivity in ~50 wt% H2SO4 solutions may be enhanced at lower temperatures, contrary to expectations. We will present temperature-dependent results of acid catalyzed condensation reactions, leading to formation of higher molecular weight products. Implications for aerosol composition and reactivity will be discussed.

  8. Beech wood Fagus sylvatica dilute-acid hydrolysate as a feedstock to support Chlorella sorokiniana biomass, fatty acid and pigment production.

    PubMed

    Miazek, Krystian; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

    2017-04-01

    This work evaluates the possibility of using beech wood (Fagus sylvatica) dilute-acid (H2SO4) hydrolysate as a feedstock for Chlorella sorokiniana growth, fatty acid and pigment production. Neutralized wood acid hydrolysate, containing organic and mineral compounds, was tested on Chlorella growth at different concentrations and compared to growth under phototrophic conditions. Chlorella growth was improved at lower loadings and inhibited at higher loadings. Based on these results, a 12% neutralized wood acid hydrolysate (Hyd12%) loading was selected to investigate its impact on Chlorella growth, fatty acid and pigment production. Hyd12% improved microalgal biomass, fatty acid and pigment productivities both in light and in dark, when compared to photoautotrophic control. Light intensity had substantial influence on fatty acid and pigment composition in Chlorella culture during Hyd12%-based growth. Moreover, heterotrophic Chlorella cultivation with Hyd12% also showed that wood hydrolysate can constitute an attractive feedstock for microalgae cultivation in case of lack of light.

  9. 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.

  10. MELCOR-H2 Benchmarking of the SNL Transient Sulfuric Acid Decomposition Experiments

    SciTech Connect

    Rodriguez, Sal B.; Gauntt, Randall O.; Gelbard, Fred; Pickard, Paul; Cole, Randy; McFadden, Katherine; Drennen, Tom; Martin, Billy; Louie, David; Archuleta, Louis; Revankar, Shripad T.; Vierow, Karen; El-Genk, Mohamed; Tournier, Jean Michel

    2007-07-01

    MELCOR is a world-renowned nuclear reactor safety analysis code that is used to simulate both light water and gas-cooled reactors. MELCOR-H2 is an extension of MELCOR that can model detailed nuclear reactors that are fully coupled with modular secondary-system components and the sulfur iodine (SI) thermochemical cycle for the generation of hydrogen and electricity. The models are applicable to both steady state and transient calculations. Previous work has shown that the hydrogen generation rate calculated by MELCOR-H2 for the SI cycle was within the expected theoretical yield, thus providing a macroscopic confirmation that MELCOR-H2's computational approach is reasonable. However, in order to better quantify its adequacy, benchmarking of the code with experimental data is required. Sulfuric acid decomposition experiments were conducted during late 2006 at Sandia National Laboratories, and MELCOR-H2 was used to simulate them. We developed an input deck based on the experiment's geometry, as well as the initial and boundary conditions, and then proceeded to compare the experimental acid conversion efficiency and SO{sub 2} production data with the code output. The comparison showed that the simulation output was typically within less than 10% of experimental data, and that key experimental data trends such as acid conversion efficiency, molar acid flow rate, and solution mole % were computed adequately by the MELCOR-H2. (authors)

  11. 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.

  12. The infrared optical constants of sulfuric acid at 250 K. [spectral reflectance measurement of aqueous solutions

    NASA Technical Reports Server (NTRS)

    Pinkley, L. W.; Williams, D.

    1976-01-01

    Results are presented for measurements of the IR spectral reflectance at near-normal incidence of aqueous solutions of sulfuric acid with acid concentrations of 75% and 95.6% by weight. Kramers-Kronig analyses of the reflectance data are employed to obtain values of the optical constants n(nu) and k(nu) in the spectral range from 400 to 6000 cm to the -1 power. The optical constants of these solutions at 250 K and 300 K are compared. It is found that in spectral regions remote from strong absorption bands, the values of the n(nu) indices obtained at 250 K agree with the values given by Lorentz-Lorenz correction of the same indices at 300 K. All absorption bands observed at 300 K are found to be present at 250 K with slight shifts in frequency and with significant differences in the k(nu) indices at the band maxima. Based on these results, it is concluded that the clouds of Venus probably consist of droplets of aqueous solutions of sulfuric acid with acid concentrations of about 75% by weight.

  13. Effects of sulfur dioxide, hydrogen peroxide and sulfuric acid on the de novo synthesis of PCDD/F and PCB under model laboratory conditions.

    PubMed

    Pekárek, V; Puncochár, M; Bures, M; Grabic, R; Fiserová, E

    2007-01-01

    In a laboratory model system consisting of fly ash from municipal waste incinerator, CuCl2 x 2H2O, NaCl and activated carbon in N2 + 10% O2 atmosphere, the de novo synthetic reactions of formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) were studied under laboratory conditions in the presence of sulfur dioxide, hydrogen peroxide, and sulfuric acid. It has been found that the formation of PCDD is suppressed by sulfur dioxide more efficiently than the formation of PCDF. A similar effect has also been observed in the presence of hydrogen peroxide. The formation of PCDF is strongly suppressed in the presence of sulfuric acid. On the basis of the experimental results and thermodynamic calculations, the following mechanisms are proposed and discussed: oxidative destruction of PCDD and PCDF oxygen rings, conversion of cupric chloride and possibly also cupric oxide into the non-reactive sulfate, and the Deacon oxychlorination processes catalyzed by cupric chloride.

  14. Acute generalized exanthematous pustulosis (AGEP) due to exposure to sulfuric acid and bromic acid vapor: a case report.

    PubMed

    Bilac, Dilek Bayraktar; Ermertcan, Aylin Turel; Ozturkcan, Serap; Sahin, M Turhan; Temiz, Peyker

    2008-01-01

    Acute generalized exanthematous pustulosis (AGEP, toxic pustuloderma, pustular drug eruption) is a not uncommon cutaneous reaction pattern that is usually related to drug administration. The eruption is of sudden onset and appears 7-10 days after the medication is started. A 22-year-old male patient who was a student at a chemical faculty attended our outpatient clinic with a complaint of pustular eruption on his face. According to his history, the eruption started with pruritus and erythema on his chin 3 days ago and spread to his face and chest. He explained that he had performed an experiment with sulfuric acid and bromic acid and was exposed to their vapor. His dermatological examination revealed erythema and pustules on his cheeks, on his chin, above his upper lip, and on his eyebrows. He also had a few pustules on his chest. There were no ocular, mucous membrane, or pulmonary symptoms. Histopathological examination of the skin biopsy specimen revealed superficial orthokeratosis, focal subcorneal pustule formation, and perivascular chronic inflammatory cell infiltration in superficial dermis. After administration of systemic antihistamines and wet dressing topically, we observed rapid healing of the lesions. Because there was no systemic drug intake in his history, we were concerned that exposure to sulfuric acid and bromic acid vapor caused AGEP in this patient. We present this rare case to show that the vapor of chemical materials may cause AGEP or other drug eruptions.

  15. 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

  16. Uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide.

    PubMed

    Liu, Ze; Ge, Maofa; Wang, Weigang

    2012-01-01

    Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, but the lack of kinetics data significantly limited the evaluation of this process in the atmosphere. Here we report the first measurement of the uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide. Isoprene cannot readily partition into the solution because of its high volatility and low solubility, which hinders its further liquid-phase oxidation. Both methacrylic acid and methyl methacrylate can enter the solutions and be oxidized by hydrogen peroxide, and steady-state uptake was observed with the acidity of solution above 30 wt.% and 70 wt.%, respectively. The steady-state uptake coefficient of methacrylic acid is much larger than that of methyl methacrylate for a solution with same acidity. These observations can be explained by the different reactivity of these two compounds caused by the different electron-withdrawing conjugation between carboxyl and ester groups. The atmospheric lifetimes were estimated based on the calculated steady-state uptake coefficients. These results demonstrate that the multiphase acid-catalyzed oxidation of methacrylic acid plays a role in secondary organic aerosol formation, but for isoprene and methyl methacrylate, this process is not important in the troposphere.

  17. Sulfuric acid speleogenesis of Carlsbad Cavern and its relationship to hydrocarbons, Delaware basin, New Mexico and Texas

    SciTech Connect

    Hill, C.A. )

    1990-11-01

    Sulfur-isotope data and pH-dependence of the mineral endellite support the hypothesis that Carlsbad Cavern and other caves in the Guadalupe Mountains were dissolved primarily by sulfuric acid rather than by carbonic acid. Floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in {sup 32}S; {delta}{sup 34}S values as low as {minus}25.8 {per thousand} (CDT) indicate that the cave sulfur and gypsum are the end products of microbial reactions associated with hydrocarbons. A model for a genetic connection between hydrocarbons in the basin and caves in the Guadalupe Mountains is proposed. As the Guadalupe Mountains were uplifted during the late Pliocene-Pleistocene, oil and gas moved updip in the basin. The gas reacted with sulfate anions derived from dissolution of the Castile anhydrite to form H{sub 2}S, CO{sub 2}, and castile limestone. The hydrogen sulfide rose into the Capitan reef along joints, forereef carbonate beds, or Bell Canyon siliciclastic beds and there reacted with oxygenated groundwater to form sulfuric acid and Carlsbad Cavern. A sulfuric-acid mode of dissolution may be responsible for large-scale porosity of some Delaware basin reservoirs and for oil-field karst reservoirs in other petroleum basins of the world. 8 figs.

  18. 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.

  19. Pervaporation of Water from Aqueous Sulfuric Acid at Elevated Temperatures Using Nafion® Membranes

    SciTech Connect

    Christopher J. Orme; Frederick F. Stewart

    2009-01-01

    The concentration of sulfuric acid by pervaporation has been studied using Nafion-112® and Nafion-117® membranes, which have been characterized in terms of flux, permeability, and selectivity at 100 ºC and 120 ºC. Feed concentrations investigated ranged from 40 to over 80 weight percent. In general, water fluxes ranged from 100-8000 g/m2h, depending on feed acid concentration and separations factors as high as 104 were observed. Membrane stability was probed using Dynamic Mechanical Analysis that revealed some embrittlement of the membranes during use. Further studies showed that the embrittlement was due to an interaction with the acid and was not induced by the operating temperature.

  20. Sulfur Cycle

    NASA Technical Reports Server (NTRS)

    Hariss, R.; Niki, H.

    1985-01-01

    Among the general categories of tropospheric sulfur sources, anthropogenic sources have been quantified the most accurately. Research on fluxes of sulfur compounds from volcanic sources is now in progress. Natural sources of reduced sulfur compounds are highly variable in both space and time. Variables, such as soil temperature, hydrology (tidal and water table), and organic flux into the soil, all interact to determine microbial production and subsequent emissions of reduced sulfur compounds from anaerobic soils and sediments. Available information on sources of COS, CS2, DMS, and H2S to the troposphere in the following paragraphs are summarized; these are the major biogenic sulfur species with a clearly identified role in tropospheric chemistry. The oxidation of SO2 to H2SO4 can often have a significant impact on the acidity of precipitation. A schematic representation of some important transformations and sinks for selected sulfur species is illustrated.