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1

Dilute-sulfuric acid pretreatment of cattails for cellulose conversion.  

PubMed

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. PMID:21807504

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

2011-10-01

2

Dilute sulfuric acid pretreatment of sunflower stalks for sugar production.  

PubMed

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 175C 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 167C and 1.3% sulfuric acid concentration. PMID:23708847

Ruiz, Encarnacin; Romero, Inmaculada; Moya, Manuel; Cara, Cristbal; Vidal, Juan D; Castro, Eulogio

2013-07-01

3

Hydrolysis of Sasa senanensis culm with dilute sulfuric acid for production of a fermentable substrate  

Microsoft Academic Search

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa senanensis was hydrolyzed with dilute sulfuric acid. When the reaction temperature was fixed at 121C, an optimum yield of xylose was\\u000a obtained by treatment with 2% sulfuric acid for 1 h. An increase in the sulfuric acid concentration or a prolonged reaction\\u000a time resulted in

Masahiro Miura; Atsushi Shimahata; Toshio Nishikawa; Masakazu Aoyama; Kiyoshi Tada; Junichi Horiuchi; Masahiro Nakahara; Chikara Sakai

2011-01-01

4

Initial design of a dilute sulfuric acid pretreatment process for aspen wood chips  

Microsoft Academic Search

A preliminary process design for dilute sulfuric acid pretreatment of aspen wood chips in order to obtain fermentable sugars\\u000a has been prepared and subjected to an economic evaluation. The process design was prepared according to experimental data\\u000a on the kinetics of dilute sulfuric acid prehydrolysis and particle size effects obtained in this study and our previous work.\\u000a The initial economic

R. Torget; M. Himmel; J. D. Wright; K. Grohmann

1988-01-01

5

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

Microsoft Academic Search

Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25g\\/l sucrose with 0.12.0% (w\\/w) sulfuric acid concentrations were treated at temperatures of 160200C for 312min.

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

2008-01-01

6

Kinetic characterization for dilute sulfuric acid hydrolysis of timber varieties and switchgrass  

Microsoft Academic Search

Hydrolysis of four timber species (aspen, balsam fir, basswood, and red maple) and switchgrass was studied using dilute sulfuric acid at 50g dry biomass\\/L under similar conditions previously described as acid pretreatment. The primary goal was to obtain detailed kinetic data of xylose formation and degradation from a match between a first order reaction model and the experimental data at

Shu Chiang Yat; Alan Berger; David R. Shonnard

2008-01-01

7

Modeling and optimization of the dilute-sulfuric-acid pretreatment of corn stover, poplar and switchgrass  

Microsoft Academic Search

Lignocellulosic biomass may be used as a potential renewable feedstock for biochemical production of ethanol as an alternative transportation fuel. However, cellulose, which is the major source of fermentable sugars in these materials, is protected by a network of lignin and hemicellulose. The dilute-sulfuric-acid pretreatment removes this protecting shield and makes the cellulose more susceptible to enzymatic digestion. In this

Alireza Esteghlalian; Andrew G. Hashimoto; John J. Fenske; Michael H. Penner

1997-01-01

8

Modeling Sucrose Hydrolysis in Dilute Sulfuric Acid Solutions at Pretreatment Conditions for Lignocellulosic Biomass  

SciTech Connect

Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25 g/l sucrose with 0.1-2.0% (w/w) sulfuric acid concentrations were treated at temperatures of 160-200 C for 3-12 min. Sucrose was observed to completely hydrolyze at all treatment conditions. However, appreciable concentrations of fructose and glucose were detected and glucose was found to be significantly more stable than fructose. Different mathematical approaches were used to fit the kinetic parameters for acid-catalyzed thermal degradation of these sugars. Since both sugars may survive dilute acid pretreatment, they could provide an additional carbon source for production of ethanol and other bio-based products.

Bower, S.; Wickramasinghe, R.; Nagle, N. J.; Schell, D. J.

2008-01-01

9

Diffusion of sulfuric acid within lignocellulosic biomass particles and its impact on dilute-acid pretreatment  

Microsoft Academic Search

Intra-particle diffusion of sulfuric acid into sugarcane bagasse, corn stover, rice straw and yellow poplar was investigated to determine the effective diffusivity of sulfuric acid within the porous biomass structure. Diffusion experiments were conducted over 2575 C for two different biomass sizes using dynamic diffusion test cells. Diffusivities of sulfuric acid in agricultural residues were significantly higher than those of

Sung Bae Kim; Y. Y Lee

2002-01-01

10

Dilute-sulfuric acid pretreatment of corn stover in pilot-scale reactor  

Microsoft Academic Search

Corn stover is a domestic feedstock that has potential to produce significant quantities of fuel ethanol and other bioenergy\\u000a and biobased products. However, comprehensive yield and carbon mass balance information and validated kinetic models for dilute-sulfuric\\u000a acid (H2SO4) pretreatment of corn stover have not been available. This has hindered the estimation of process economics and also limited\\u000a the ability to

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

2003-01-01

11

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

PubMed

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. PMID:23972397

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

12

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

PubMed Central

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

2013-01-01

13

A study on the pretreatment of a sugarcane bagasse sample with dilute sulfuric acid.  

PubMed

Experiments based on a 2(3) central composite full factorial design were carried out in 200-ml stainless-steel containers to study the pretreatment, with dilute sulfuric acid, of a sugarcane bagasse sample obtained from a local sugar-alcohol mill. The independent variables selected for study were temperature, varied from 112.5C to 157.5C, residence time, varied from 5.0 to 35.0 min, and sulfuric acid concentration, varied from 0.0% to 3.0% (w/v). Bagasse loading of 15% (w/w) was used in all experiments. Statistical analysis of the experimental results showed that all three independent variables significantly influenced the response variables, namely the bagasse solubilization, efficiency of xylose recovery in the hemicellulosic hydrolysate, efficiency of cellulose enzymatic saccharification, and percentages of cellulose, hemicellulose, and lignin in the pretreated solids. Temperature was the factor that influenced the response variables the most, followed by acid concentration and residence time, in that order. Although harsher pretreatment conditions promoted almost complete removal of the hemicellulosic fraction, the amount of xylose recovered in the hemicellulosic hydrolysate did not exceed 61.8% of the maximum theoretical value. Cellulose enzymatic saccharification was favored by more efficient removal of hemicellulose during the pretreatment. However, detoxification of the hemicellulosic hydrolysate was necessary for better bioconversion of the sugars to ethanol. PMID:21210180

Canilha, Larissa; Santos, Victor T O; Rocha, George J M; Almeida e Silva, Joo B; Giulietti, Marco; Silva, Silvio S; Felipe, Maria G A; Ferraz, Andr; Milagres, Adriane M F; Carvalho, Walter

2011-09-01

14

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

PubMed

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. PMID:19846294

Rodrigues, Rita de Cssia L B; Rocha, George J M; Rodrigues, Durval; Filho, Hlcio J I; Felipe, Maria das Graas A; Pessoa, Adalberto

2010-02-01

15

Kinetic characterization for dilute sulfuric acid hydrolysis of timber varieties and switchgrass.  

PubMed

Hydrolysis of four timber species (aspen, balsam fir, basswood, and red maple) and switchgrass was studied using dilute sulfuric acid at 50 g dry biomass/L under similar conditions previously described as acid pretreatment. The primary goal was to obtain detailed kinetic data of xylose formation and degradation from a match between a first order reaction model and the experimental data at various final reactor temperatures (160-190 degrees C), sulfuric acid concentrations (0.25-1.0% w/v), and particle sizes (28-10/20 mesh) in a glass-lined 1L well-mixed batch reactor. Reaction rates for the generation of xylose from hemicellulose and the generation of furfural from xylose were strongly dependent on both temperature and acid concentration. However, no effect was observed for the particle sizes studied. Oligomer sugars, representing incomplete products of hydrolysis, were observed early in the reaction period for all sugars (xylose, glucose, arabinose, mannose, and galactose), but were reduced to low concentrations at later times (higher hemicellulose conversions). Maximum yields for xylose ranged from 70% (balsam) to 94% (switchgrass), for glucose from 10.6% to 13.6%, and for other minor sugars from 8.6% to 58.9%. Xylose formation activation energies and the pre-exponential factors for the timber species and switchgrass were in a range of 49-180 kJ/mol and from 7.5 x 10(4) to 2.6 x 10(20)min(-1), respectively. In addition, for xylose degradation, the activation energies and the pre-exponential factors ranged from 130 to 170 kJ/mol and from 6.8 x 10(13) to 3.7 x 10(17)min(-1), respectively. There was a near linear dependence on acid concentration observed for xylose degradation. Our results suggest that mixtures of biomass species may be processed together and still achieve high yields for all species. PMID:17904838

Yat, Shu Chiang; Berger, Alan; Shonnard, David R

2008-06-01

16

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

Microsoft Academic Search

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 (4.9g\\/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

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

2011-01-01

17

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

SciTech Connect

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.

Helm, R.F.

1987-01-01

18

Micro Electrochemical Machining of 3D Micro Structure Using Dilute Sulfuric Acid  

Microsoft Academic Search

Micro electrochemical machining (ECM) using ultra short pulses with tens of nanosecond duration is presented. 0.1 M sulfuric acid was used as electrolyte and 3D micro structures were machined on stainless steel. To prevent taper, a disk-type electrode was introduced. Using the disk-type electrode, taper could be eliminated. To improve productivity, multiple electrodes were applied and multiple structures were machined

B. H. Kim; C. W. Na; Y. S. Lee; D. K. Choi; C. N. Chu

2005-01-01

19

Sulfuric acid emissions from light duty vehicles  

Microsoft Academic Search

Systems used by the Office of Mobile Source Air Pollution Control of EPA to measure and analyze automotive sulfuric acid emissions are discussed. This system involved mixing the entire vehicle exhaust with dilution air in a dilution tunnel. Sulfuric acid samples are collected by passing a small portion of the dilute exhaust through Fluoropore filters. The sulfuric acid content of

J. H. Somers; R. Lawrence; C. E. Fett; T. M. Baines; R. J. Garbe

1976-01-01

20

Porosity and its effect on the digestibility of dilute sulfuric acid pretreated corn stover.  

PubMed

Enzyme accessibility has been proposed as a limiting factor in the enzymatic conversion of the cellulose in biomass to glucose. Prior work has shown a strong correlation between porosity, measured as the change in the volume of pores accessible to a cellulase-sized molecule, and the initial digestibility of biomass pretreated by various methods. The goal of this work was to determine if porosity was one of the factors governing the overall enzymatic digestibility of the cellulose in dilute acid pretreated biomass. The porosity of wet pretreated corn stover was determined using the methods of solute exclusion and 1H nuclear magnetic resonance (NMR) thermoporometry. The solute exclusion method identified differences in the accessible pore volume of the pretreated samples compared to untreated corn stover; however, only very small differences in porosity were observed among samples pretreated with a range of severities, giving ethanol yields from 70 to 96%. No correlation was found between the volume accessible to an enzyme-sized molecule (diameter estimated to be 51 A) and the digestibility of the cellulose in dilute acid pretreated corn stover. 1H NMR thermoporometry was used to measure the amount of water in pores ranging from 20 to 200 A. As was the case for the solute exclusion method, a difference was observed in the pore volume of untreated and acid pretreated corn stover, but no significant differences in pore volume were measured for the different pretreated samples. PMID:17335219

Ishizawa, Claudia I; Davis, Mark F; Schell, Daniel F; Johnson, David K

2007-04-01

21

Sulfuric acid-sulfur heat storage cycle  

DOEpatents

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.

Norman, John H. (LaJolla, CA)

1983-12-20

22

Dilute acid hydrolysis of softwoods  

Microsoft Academic Search

Whole tree chips obtained from softwood forest thinnings were converted to ethanol via a two-stage dilute acid hydrolysis\\u000a followed by yeast fermentation. The chips were first impregnated with dilute sulfuric acid, then pretreated in a steam explosion\\u000a reactor to hydrolyze, more than 90% of the hemicellulose and approx 10% of the cellulose. The hydrolysate was filtered and\\u000a washed with water

Quang A. Nguyen; Melvin P. Tucker; Fred A. Keller; Delicia A. Beaty; Kevin M. Connors; Fannie P. Eddy

1999-01-01

23

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

PubMed

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%. PMID:24420285

Tai, Chao; Keshwani, Deepak

2014-03-01

24

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

PubMed

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. PMID:21463940

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

2011-05-01

25

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

PubMed

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 148C, 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 170C, 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. PMID:24342947

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

2014-02-01

26

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

PubMed Central

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

2012-01-01

27

Catalytic decomposition of hydrogen peroxide by ferric ion in dilute sulfuric acid solutions  

NASA Astrophysics Data System (ADS)

Hydrogen peroxide decomposition in acidic solutions is catalyzed by the free ferric ion, Fe3+. The following rate law for this reaction is determined by the initial rate method in solutions similar to those used for acidic in situ uranium leaching: - (dm_{H_2 O_2 } /dt)_{25^circ C} = k{(m_{H_2 O_2 } )(m_{Fe} 3 - )}/{(m_H - )} where k = 4.3 10-3 s1 at 25 C. From 25 to 50 C, the activation energy is 85.6 kJ/mol. The decomposition of hydrogen peroxide proceeds by a particular redox reaction sequence that depends on the ratio of the concentrations of hydrogen peroxide to free ferric ion. The rate law determined here is consistent with the form derived from the redox sequence for the case where the ratio of hydrogen peroxide to free ferric ion concentration is greater than 1.0. The magnitude of the rate constant indicates that the decomposition of hydrogen peroxide may cause rapid loss of this oxidant in leaching solutions containing ferric ion.

Eary, L. E.

1985-06-01

28

Dilute-Acid Hydrolysis of Lignocellulosic Biomass  

Microsoft Academic Search

In recent years, treatment of lignocellulosic biomass with dilute sulfuric acid has been primarily used as a means of hemicellulose\\u000a hydrolysis and pretreatment for enzymatic hydrolysis of cellulose. A significant advancement has also been made in the area\\u000a of dilute acid hydrolysis of cellulose. An overview of reactor theory as it applies to the dilute acid hydrolysis and recent\\u000a developments

Y. Y. Lee; Prashant Iyer; R. W. Torget

29

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 is for information only and not for ...

30

Acid recovery from waste sulfuric acid by diffusion dialysis  

Microsoft Academic Search

In the process of sulfuric acid production from pyrite, there is a lot of waste acid produced in fume washing with dilute\\u000a acid. Acid recovery from this sort of waste sulfuric acid by diffusion dialysis is studied in the paper. The mass transfer\\u000a dialysis coefficient of sulfuric acid of the membrane AFX is measured, the effect of the flowrate of

Guiqing Zhang; Qixiu Zhang; Kanggen Zhou

1999-01-01

31

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

PubMed

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. PMID:24104688

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

2014-01-01

32

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

PubMed

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. PMID:19031051

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

2009-05-01

33

Saccharification of concentrated brewing bagasse slurries with dilute sulfuric acid from producing acetone-butanol by Clostridium acetobutylicum  

SciTech Connect

A comprehensive kinetic study of the acid hydrolysis of concentrated brewing bagasse slurries was performed. The use of simple series reaction model was found to be suitable when a heterogeneous correction (pseudo-substrate-inhibition) is taken into account in slurries with low liquid-to-biomass ratios. Rate constants are shown to be dependent not only on temperature and acid concentration but essentially also on the initial biomass concentration. Actual rate constants, activation energies, and acid and substrate reaction orders are reported for xylan, arabinan, and ..cap alpha..-glucan acid saccharification. There is a threshold acid loading necessary to overcome the 80% conversion, but no threshold has been found to overcome the neutralizing property of cellulosic materials. Reversible acid capture from brewing bagasse has been postulated. The highest monosaccharide concentration into hydrolyzates has been found (65 g/L) after 10 h treatment, but because of economic considerations, a mean-concentrated slurry (156 g/L) was treated with 0.3 M H/sub 2/SO/sub 4/ at 96/sup 0/C, thus obtaining 45.5 g/L monosaccharides in 5 h with 50% less furfural content. After pH regulation only, growth of Clostridium acetobutylicum has been obtained, although complete sugar consumption has not been achieved. Experiments are now underway to reach complete digestion and to investigate the increase of enzymic accessibility into residual substrate rich in cellulose.

Juanbaro, J.; Puigjaner, L.

1986-01-01

34

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

PubMed

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, ?-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. PMID:20953894

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

2011-08-01

35

Sequential hydrolysis of hemicellulose and lignin in lignocellulosic biomass by two-stage percolation process using dilute sulfuric acid and ammonium hydroxide  

Microsoft Academic Search

To obtain the total fractionation and pretreatment of the corn stover, two-stage percolation process was investigated. This\\u000a process consists of two steps: use of 0.07 wt% sulfuric acid for hemicellulose recovery in first stage and ARP (ammonia recycled\\u000a percolation) in the following stage for lignin recovery. Among tested conditions, the best conditions of two-stage process\\u000a were as follows: 1st stage;

Tae Hyun Kim

36

Two-stage dilute-acid pretreatment of softwoods  

Microsoft Academic Search

Whole treechips obtained from softwood forest thinnings were pretreated via single-and two-stage dilute-sulfuric acid pretreatment.\\u000a Whole-tree chips were impregnated with dilute sulfuric acid and steam treated in a 4-L steam explosion reactor. In single-stage\\u000a pretreatment, wood chips were treated using a wide range of severity. In two-stage pretreatment, the first stage was carried\\u000a out at low severity tomaximize hemicellulose recovery.

Quang A. Nguyen; Melvin P. Tucker; Fred A. Keller; Fannie P. Eddy

2000-01-01

37

Process for forming sulfuric acid  

DOEpatents

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.

Lu, Wen-Tong P. (Upper St. Clair, PA)

1981-01-01

38

Molecular Structure of Sulfuric Acid  

NSDL National Science Digital Library

H2SO4 was discovered by alchemists and made from heating a compound of iron sulfate. In 1740, sulfuric acid was produced for commercial sale. Sulfuric acid is a very strong acid which is used in car batteries. The acid disassociates in water to give two protons and sulfate. This acid can destroy flesh and cause blindness. It was discovered in the 19th century that adding sulfuric acid to soil produces phosphorus, which is beneficial to plants; hence, sulfuric acid is used as a fertilizer in the form of super phosphate and ammonium sulfate. Sulfuric acid is also used to refine petroleum and process metals, and is found in paints and car batteries.

2002-08-15

39

Sulfuric acid as autocatalyst in the formation of sulfuric acid.  

PubMed

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 kcalmol(-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. PMID:23198746

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

2012-12-26

40

Dry dilute acid pretreatment by co-currently feeding of corn stover feedstock and dilute acid solution without impregnation.  

PubMed

Impregnation of lignocellulose materials with dilute acid solution is a routine operation in conventional dilute acid pretreatment. The dry dilute acid pretreatment (DDAP) at high solids content up to 70% is naturally considered to require longer impregnation time. In this study, a co-currently feeding operation of corn stover and dilute sulfuric acid solution without any impregnation was tested for DDAP. The DDAP pretreated corn stover without impregnation is found to be essentially no difference in pretreatment efficiency compared to those with impregnation in the helically agitated reactor. The yield from cellulose to ethanol in SSF again shows no obvious difference between the DDAP pretreated corn stover with and without impregnation. This study suggests that impregnation in DDAP was not necessary under the helical agitation mixing. The results provided a useful way of cost reduction and process simplification in pretreatment. PMID:24630497

He, Yanqing; Zhang, Jian; Bao, Jie

2014-04-01

41

Sulfuric Acid on Europa's Surface and the Radiolytic Sulfur Cycle  

NASA Astrophysics Data System (ADS)

Galileo infrared spectra of Europa's surface show distorted water bands that have been attributed to hydrated evaporite salts (McCord et al., J. Geophys. Res. 104, 11827, 1999) or to the scattering properties of ice (Dalton and Clark, Bull. Am. Astron. Soc. 30, 1081, 1998). Using new laboratory spectra, we show that hydrated sulfuric acid can explain Europa's spectra and further show that this species is a product of radiolysis. Sulfuric acid on Europa occurs as the radiolytically stable octahydrate and hemihexahydrate and is a major surface component, along with water ice. The sulfuric acid concentration correlates spatially with Europa's visually dark material, which we identify as radiolytically altered sulfur polymers. Radiolysis by incident jovian plasma continuously cycles sulfur between three chemical reservoirs: sulfuric acid, polymerized sulfur, and sulfur dioxide, with the acid being about 50 times more abundant than the other forms because of the stability of the sulfate anion under irradiation. The original source of sulfur may be incident iogenic sulfur ions or endogenic sulfur compounds that are altered by radiolysis. Geological processes can bury and redistribute the sulfurous material, producing a sulfur-rich crust and a non-uniform surface distribution. The low melting point of sulfuric acid and its ability to supercool may facilitate geological processes. Europa's magnetic response may be influenced by the electrical conductivity of sulfuric acid.

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

1999-09-01

42

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

Microsoft Academic Search

We report laboratory studies on the 0.8MeV proton irradiation of ices composed of sulfuric acid (H2SO4), sulfuric acid monohydrate (H2SO4H2O), and sulfuric acid tetrahydrate (H2SO44H2O) between 10 and 180K. Using infrared spectroscopy, we identify the main radiation products as H2O, SO2, (S2O3)x, H3O+, HSO4-, and SO42-. At high radiation doses, we find that H2SO4 molecules are destroyed completely and that

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

2011-01-01

43

Sulfuric acid in the Venus clouds  

NASA Technical Reports Server (NTRS)

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.

Sill, G. T.

1972-01-01

44

Sulfuric acid bleaching of kraft pulp III: reactivity of kraft pulping-resistant structures under acidic conditions  

Microsoft Academic Search

To investigate the bleaching mechanism, a lignincarbohydrate complex (LCC) model compound, a vinyl ether-type lignin model\\u000a dimer, and a hexeneuronic acid model compound were treated with dilute sulfuric acid of different pHs. Beech kraft pulp and\\u000a red pine kraft pulp were also treated with dilute sulfuric acid and then extracted with aqueous alkali. The amount of hexeneuronic\\u000a acid degradation products

Tsutomu Ikeda; Yoichi Tomimura; Kengo Magara; Mitsuro Ishihara; Shuji Hosoya

1999-01-01

45

Determination of the activity of hydrogen ions in dilute sulfuric acids by use of an ionic liquid salt bridge sandwiched by two hydrogen electrodes.  

PubMed

The activities of hydrogen ions in 20-200 ?mol dm(-3) H(2)SO(4) solution were estimated by use of an ionic liquid salt bridge (ILSB), made of tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide (TBMOEPC(2)C(2)N), sandwiched by two hydrogen electrodes. The experimental pH values (pH = -log a(H), where a(H) is the activity of hydrogen ions) were in good agreement, within 0.01 pH unit, with those calculated using the Pitzer model. The difference between the experimental and theoretical pH values at 50 ?mol dm(-3) H(2)SO(4) solution was much smaller than that obtained by use of a glass electrode in combination with a reference electrode with a concentrated KCl salt bridge. The source of the small deviation can be explained by the residual diffusion potential due to the dissolution of TBMOEPC(2)C(2)N in the H(2)SO(4) solution (W) and the resultant increase in the ionic strength of W. The use of a reference electrode equipped with an ILSB opens the way to accurately estimate the pH in dilute aqueous solutions, for which we have not had effective means. PMID:21126098

Shibata, Manabu; Sakaida, Hideaki; Kakiuchi, Takashi

2011-01-01

46

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

PubMed

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, 160C, 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. PMID:23747442

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

2013-08-01

47

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

NASA Astrophysics Data System (ADS)

We report laboratory studies on the 0.8 MeV proton irradiation of ices composed of sulfuric acid (H 2SO 4), sulfuric acid monohydrate (H 2SO 4H 2O), and sulfuric acid tetrahydrate (H 2SO 44H 2O) between 10 and 180 K. Using infrared spectroscopy, we identify the main radiation products as H 2O, SO 2, (S 2O 3) x, H 3O +, HSO4-, and SO42-. At high radiation doses, we find that H 2SO 4 molecules are destroyed completely and that H 2SO 4H 2O is formed on subsequent warming. This hydrate is significantly more stable to radiolytic destruction than pure H 2SO 4, falling to an equilibrium relative abundance of 50% of its original value on prolonged irradiation. Unlike either pure H 2SO 4 or H 2SO 4H 2O, the loss of H 2SO 44H 2O 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 SO 2 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.

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

2011-09-01

48

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

49

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

PubMed

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 1-5min to 15-20min. To avoid undesirable sugar degradation and inhibitor generation, temperatures should be controlled below 170C. When the sulfuric acid-to-lignocellulosic biomass ratio was kept at 0.025g acid/g dry biomass, a cellulose-to-glucose conversion of 72.7% can be achieved at an enzyme loading of 0.016g/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 to be the key factor in effective dilute acid pretreatment. PMID:22167347

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

2012-05-01

50

Sulfuric acid leaching of Turkish chromite concentrate  

Microsoft Academic Search

In this work a high grade chromite concentrate obtained from PinarbasiKayseri district of Turkey was reacted with a solution of sulfuric acid and perchloric acid. The effect of sulfuric acid concentration, temperature, duration, and perchloric acid addition on leach recovery was studied. At the end of leach reaction chromium appeared in the solution as Cr3+ and it did not change

A. Geveci; Y. Topkaya; E. Ayhan

2002-01-01

51

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

Microsoft Academic Search

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

T. Hsu; Q. Nguyen

1995-01-01

52

Leaching behavior of ilmenite with sulfuric acid  

Microsoft Academic Search

A study of the rate of dissolution of ilmenite in sulfuric acid solutions has been carried out. The effects of temperature, particle size, stirring speed, and concentration of sulfuric acid on the rate of dissolution of ilmenite has been investigated. Temperature range studied in this investigation was 88 to 115C, and the Arrhenius activation energy was found to be 64.4

K. N. Han; T. Rubcumintara; M. C. Fuerstenau

1987-01-01

53

The Microbial Karst Sulfuric Acid Dynamo  

Microsoft Academic Search

The original model for sulfuric acid speleogenesis attributes limestone dissolution to the oxidation of gaseous H2S to sulfuric acid on limestone cave walls (Egemeier 1981). This model has recently been reexamined in Lower Kane Cave, Wyoming (USA), where the most intense limestone dissolution appears to be the result of microbial colonization of limestone surfaces below the water table (Engel et

E. Lyon; K. Meyer; B. Koffman; S. Galdenzi; J. Macalady

2004-01-01

54

DYNAMIC DILUTION SYSTEM FOR AUDITING AMBIENT SULFUR DIOXIDE ANALYZERS  

EPA Science Inventory

This paper discusses the development, evaluation, and field performance of a device designed to provide accurate sulfur dioxide concentration standards suitable for auditing the accuracy of continuous, ambient SO2 monitors. This compact, lightweight, device has been subjected to ...

55

Are the clouds of Venus sulfuric acid.  

NASA Technical Reports Server (NTRS)

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.

Young, A. T.

1973-01-01

56

Purification of dilute hydrofluoric acid by commercial ion exchange resins  

Microsoft Academic Search

This paper describes the results from an experimental study of the purification of dilute hydrofluoric acid (5wt.%) by ion exchange. Hydrofluoric acid was prepared by dilution from technical grade concentrated HF; important amounts of metal impurities were found in the diluted acid, mainly Na, Fe, As, B, Ca, K, Mg, Mn, Mo, PO43?, and Ti. The semiconductor industry developed the

I. Fernndez-Olmo; J. L. Fernndez; A. Irabien

2007-01-01

57

Vapor phase nitration of benzene over solid acid catalysts IV. Nitration with nitric acid (3); supported sulfuric acid catalyst with co-feeding of a trace amount of sulfuric acid  

Microsoft Academic Search

In the vapor phase nitration of benzene with diluted nitric acid, we have succeeded in keeping a high nitration activity of the supported sulfuric acid catalyst for more than 2 months by co-feeding a trace amount of sulfuric acid (H2SO4\\/HNO3=1\\/5000 (wt. ratio)). The results after 60 days on-stream over 10wt.%H2SO4\\/SiO2 catalyst are as follows: yield of nitrobenzene (NB), 93% based

H Sato; K Nagai; H Yoshioka; Y Nagaoka

1999-01-01

58

Commercial Alloys for Sulfuric Acid Vaporization in Thermochemical Hydrogen Cycles  

SciTech Connect

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-based commercial alloys. The corrosion rates in these tests are reported and how they may or may not relate to the corrosion behavior in an operating thermochemical cycle is discussed.

Thomas M. Lillo; Karen M. Delezene-Briggs

2005-10-01

59

Engineering analysis of the production of xylose by dilute acid hydrolysis of hardwood hemicellulose  

Microsoft Academic Search

Numerical simulations of various reactors for the production of xylose from hardwood hemicellulose by dilute sulfuric acid hydrolysis have been developed to analyze the effects on reactor performance of heat and mass transfer as well as reaction kinetics. An economic objective function representing the incremental cost of producing a 10% xylose solution for fermentation to ethanol was calculated from the

Mark T. Maloney; Thomas W. Chapman; Andrew J. Baker

1986-01-01

60

Dilute acid pretreatment of rye straw and bermudagrass for ethanol production  

Microsoft Academic Search

Ethanol production from lignocellulosic materials provides an alternative energy production system. Rye and bermudagrass that are used in hog farms for nutrient uptake from swine wastewater have the potential for fuel ethanol production because they have a relative high cellulose and hemicellulose content. Dilute sulfuric acid pretreatment of rye straw and bermudagrass before enzymatic hydrolysis of cellulose was investigated in

Ye Sun; Jay J. Cheng

2005-01-01

61

Friction and wear of iron in sulfuric acid  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

62

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

PubMed

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

Chimento, R J; Lorente, E; Gispert-Guirado, F; Medina, F; Lpez, F

2014-10-13

63

Process for eliminating diluted sulfur oxides in combustion exhaust gases  

Microsoft Academic Search

A process is disclosed for eliminating sulfur oxides from combustion exhaust gases, comprising the steps of dividing the combustion exhaust gases into a first stream and a second stream, and passing the first stream through a first activated carbon bed which was previously washed with water, thereby drying the activated carbon, cooling the first stream, and removing a substantial portion

S. Hori; T. Inoue; S. Yamamoto; K. Tatara; M. Kitagawa; M. Watanabe; Y. Okada; N. Negishi

1978-01-01

64

Sulfuric Acid on Europa's Surface and the Radiolytic Sulfur Cycle  

Microsoft Academic Search

Galileo infrared spectra of Europa's surface show distorted water bands that have been attributed to hydrated evaporite salts (McCord et al., J. Geophys. Res. 104, 11827, 1999) or to the scattering properties of ice (Dalton and Clark, Bull. Am. Astron. Soc. 30, 1081, 1998). Using new laboratory spectra, we show that hydrated sulfuric acid can explain Europa's spectra and further

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

1999-01-01

65

Ionic mechanisms for heterogeneous stratospheric reactions and ultraviolet photoabsorption cross sections for NO2(+), HNO3, and NO3(-) in sulfuric acid  

Microsoft Academic Search

Room temperature photo-absorption cross sections between 180 and 340 nm for potassium nitrate dissolved in sulfuric acid-water solutions of 0, 80, and 96 percent sulfuric acid by mass are presented. The predominant nitrogen-containing species are the nitrate anion (NO3(-)) in pure water or dilute sulfuric acid solutions, molecular nitric acid (HNO3) in 80 percent sulfuric acid, and the nitronium ion

Joel D. Burley; H. S. Johnston

1992-01-01

66

Atmospheric Emissions from Sulfuric Acid Manufacturing Processes.  

National Technical Information Service (NTIS)

The report has been prepared to provide reliable information on atmospheric emissions from sulfuric acid manufacturing plants and on method and equipment normally employed to limit these emissions to satisfactory levels. Background information is included...

S. T. Cuffe C. M. Dean

1965-01-01

67

Process for Producing Sulfurous Acid Treated Alumina.  

National Technical Information Service (NTIS)

The activated alumina is effective for bleaching refined cottonseed oil. It is prepared by soaking ground activated alumina with an aqueous solution of sulfurous acid until a specific saturation is reached. The alumina is then removed from the solution an...

W. A. Pons J. C. Kuck V. L. Frampton

1964-01-01

68

Leaching behavior of ilmenite with sulfuric acid  

Microsoft Academic Search

A study of the rate of dissolution of ilmenite in sulfuric acid solutions has been carried out. The effects of temperature,\\u000a particle size, stirring speed, and concentration of sulfuric acid on the rate of dissolution of ilmenite has been investigated.\\u000a Temperature range studied in this investigation was 88? to 115?C, and the Arrhenius activation energy was found to be 64.4

K. N. Han; T. Rubcumintara; M. C. Fuerstenau

1987-01-01

69

Optimization of dilute acid hydrolysis of Enteromorpha  

NASA Astrophysics Data System (ADS)

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 121C. 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.

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

2011-11-01

70

46 CFR 151.50-21 - Sulfuric acid.  

Code of Federal Regulations, 2010 CFR

...5 2010-10-01 2010-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping...CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid...

2010-10-01

71

46 CFR 151.50-21 - Sulfuric acid.  

Code of Federal Regulations, 2010 CFR

...5 2009-10-01 2009-10-01 false Sulfuric acid. 151.50-21 Section 151.50-21 Shipping...CARGOES Special Requirements § 151.50-21 Sulfuric acid. (a) How sulfuric acid may be carried. (1) Sulfuric acid...

2009-10-01

72

Topsoe`s Wet gas Sulfuric Acid (WSA) process: An alternative technology for recovering refinery sulfur  

Microsoft Academic Search

The Topsoe Wet gas Sulfuric Acid (WSA) process is a catalytic process which produces concentrated sulfuric acid from refinery streams containing sulfur compounds such as HS (Claus plant feed), Claus plant tail gas, SO (FCC off-gas, power plants), and spent sulfuric acid (alkylation acid). The WSA process recovers up to 99.97% of the sulfur value in the stream as concentrated

1995-01-01

73

Sulfuric acid versus elemental sulfur as by-products. Final report  

Microsoft Academic Search

An economic comparison of sulfuric acid production and sulfur recovery processes was made on eastern coal feeds in this study. Sulfuric acid is the more attractive product whenever assured markets are available, on the basis of rail transportation of by-products. The capital cost is higher for a plant to recover the sulfur, and the product value is lower per unit

1978-01-01

74

Sulfuric acid in the Venus clouds.  

NASA Technical Reports Server (NTRS)

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.

Sill, G. T.

1972-01-01

75

Dilute acid/metal salt hydrolysis of lignocellulosics  

DOEpatents

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.

Nguyen, Quang A. (Golden, CO); Tucker, Melvin P. (Lakewood, CO)

2002-01-01

76

Dilute-acid pretreatment of distillers' grains and corn fiber.  

PubMed

Distillers' grains and corn fiber are the coproducts of the dry grind and wet corn milling industries, respectively. Availability of distillers' grains and corn fiber at the ethanol plant and their high levels of lignocellulosic material make them attractive feedstock for conversion to ethanol. In this study, dilute sulfuric acid hydrolysis for the conversion of distillers' grains and corn fiber to monomeric sugars and the formation of furfural were investigated. The extent of solubilization of biomass beyond monomeric sugars was also monitored. Biomass loadings in the range of 5-20 wt.% at 5% intervals, acid concentrations in the range of 0.5-1.5 vol.% at 0.5% intervals, and temperatures of 120 and 140 degrees C were studied. The highest yields of monomeric sugars were observed when the least amount of biomass loading was pretreated with the highest concentration of sulfuric acid and when the temperature was 140 degrees C. For the majority of the cases under consideration, the most effective period of hydrolysis appeared to be during the initial 20-30 min of the reaction. Formation of furfural during the course of hydrolysis was significantly lower at 120 degrees C and also lower for the distillers' grains samples compared with the corn fiber samples. The total amount of the solubilized matter during the hydrolysis was significantly higher than the amount of the monomeric sugars. Analyses according to standard procedure were performed to quantify moisture, oil, carbohydrates, and ash in distillers' grains and corn fiber samples. The total carbohydrate content of distillers' grains and corn fiber were 57.7+/-2.0 and 77.0+/-1.0 wt.%, respectively. The presented results will provide a foundation for the suitability of the pretreated distillers' grains and corn fiber for enzymatic hydrolysis step. PMID:19773157

Noureddini, H; Byun, J

2010-02-01

77

Sedimentation of sulfuric acid in acid tars from current production  

Microsoft Academic Search

Acid tars obtained in treating T-750, KhF-12, and I-8A oils were investigated for purposes of recovering sulfuric acid and asphalt binders from the compositions and of determining the effects of storage time on the recovery. The consumption and sedimentation levels of sulfuric acid during storage for different periods and at different temperatures were assessed. The characteristics of an asphalt binder

T. L. Denisova; A. F. Frolov; A. N. Aminov; S. P. Novosel'tsev

1987-01-01

78

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

Microsoft Academic Search

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

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

2005-01-01

79

Comparison of microbial sulfuric acid production in sewage sludge from added sulfur and thiosulfate  

Microsoft Academic Search

Microbial leaching is one of the most attractive methods of removing toxic metals from sewage sludge. Sulfuric acid produced by indigenous microflora by the oxidation of elemental sulfur and sulfur compounds solubilizes toxic metals. The oxidation of sulfur compounds can be achieved by the direct oxidation to sulfates or by indirect oxidation, through the production and accumulation of soluble intermediate

R. D. Tyagi; J. F. Blais; L. Deschenes; P. Lafrance; J. P. Villeneuve

1994-01-01

80

Charles H. Winston and Confederate Sulfuric Acid.  

ERIC Educational Resources Information Center

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)

Riethmiller, Steven

1995-01-01

81

EFFECTS OF SULFURIC ACID AEROSOLS ON VEGETATION  

EPA Science Inventory

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

82

Nitrosyl sulfuric acid and stratospheric aerosols  

Microsoft Academic Search

From information found in the atmospheric and chemical literature, we propose that nitrosyl sulfuric acid (NSA), NOHSO4, may play an important role in stratospheric chemistry. In one study, NSA was observed as a slurry of crystals in about a third of the aerosol particles collected between 15 and 20 km. From the chemical literature, we find that NSA is formed

Joel D. Burley; H. S. Johnston

1992-01-01

83

Optimization studies in sulfuric acid production  

Microsoft Academic Search

Current legislation imposes tighter restrictions to reduce the impact of process industry on environment. This work presents the dynamic simulation and optimization results for an existing sulfuric acid plant. Operational problems may occur when the process is disturbed due to production rate changes or catalyst deactivation, the non-linear response of the plant leading to sustained oscillations. Since the plant is

Anton A. Kiss; Costin S. Bildea; Peter J. T. Verheijen

2006-01-01

84

Comparative uptake of sulfur in sulfur dioxide and acid rain by corn (Zea mays L. )  

SciTech Connect

This study has compared and evaluated the absorption and accumulation of sulfur from the two major forms of sulfur pollution (sulfur dioxide and sulfur containing acid rain), by seedlings of corn (Zea mays L.). Plants were exposed to matched treatments containing equivalent ..mu..moles S/treatment in sulfur dioxide or simulated acid rain containing sulfuric acid. Pollution levels were chosen to represent low, medium and high ambient pollutant concentrations (0.13, 1.3 and 130.0 ..mu..moles S/treatment). The uptake and distribution of sulfur by plants was followed by using radioactively labelled sulfur (35-S) in both pollutants. Plants were exposed to the pollutants via a single injection of sulfur dioxide or by rainfall simulators with acid rain treatments. From the sulfur dioxide concentrations evaluated (0.67; 1.00; 2.60; 6.70; and 16 ppm), maximum absorption occurred at the highest concentration while sulfur was more efficiently absorbed at lower concentrations. Absorption of sulfur by plants exposed to acid rain (pH 5.4; 4.4; 3.4; and 2.6) was higher with high sulfur/low pH treatments. pH per se, was not responsible for increased sulfur absorption at low pH treatments. Of the total sulfur associated with the plant following exposure to sulfur dioxide and acid rain, 55% and 97%, respectively was not absorbed, and could be released after one minute of a foliar wash. At each equivalent concentration of sulfur, corn seedlings absorbed significantly greater amounts of sulfur from sulfur dioxide than from acid rain.

Simon, J.E.

1984-01-01

85

Sulfuric acid pressure leaching of nickeliferous limonites  

Microsoft Academic Search

This laboratory study examines the sulfuric acid pressure leaching characteristics of nickeliferous limonite samples from\\u000a South New Caledonia. The effect of temperature (225?C to 300?C), acid-to-ore ratio (0.21 to 0.30), pct solids (10 to 45),\\u000a particle size (-20 to -270 mesh), and agitation (50 to 600 rpm) on nickel extraction and selectivity are discussed. For overall\\u000a improvement of the leach

E. C. Chou; P. B. Queneau; R. S. Rickard

1977-01-01

86

Zirconium in a sulfuric acid pickling application  

SciTech Connect

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

Yau, T.L.

1988-01-01

87

46 CFR 151.50-21 - Sulfuric acid.  

Code of Federal Regulations, 2013 CFR

...that of 66° Baumé commercial sulfuric acid, may...that of 52° Baumé commercial sulfuric acid, may...greater than that of commercial sulfuric acid as prescribed...this section. (b) Heating coils will be the only...During cargo transfer, a water hose shall be...

2013-10-01

88

Modeling of countercurrent shrinking-bed reactor in dilute-acid total-hydrolysis of lignocellulosic biomass  

Microsoft Academic Search

A mathematical model was developed for a countercurrent shrinking-bed reactor to investigate its performance in dilute-acid pretreatment\\/hydrolysis of lignocellulosic biomass. The results indicate that bed shrinking provides a positive effect on both hemicellulose and cellulose hydrolysis resulting high yield and product concentration. The effect of bed shrinking is more profound on cellulose hydrolysis than on hemicellulose hydrolysis. With dilute sulfuric

Y. Y. Lee; Zhangwen Wu; R. W. Torget

2000-01-01

89

A comparison of chromic acid and sulfuric acid anodizing  

NASA Technical Reports Server (NTRS)

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.

Danford, M. D.

1992-01-01

90

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

Microsoft Academic Search

Recent research work in-house both at Auburn University and National Renewable Energy Laboratory has demonstrated that extremely\\u000a low concentrations of acid (e.g., 0.050.2 wt% sulfuric acid) and high temperatures (e.g., 200230C) are reaction conditions\\u000a that can be effectively applied for hydrolysis of the cellulosic component of biomass. These conditions are far from those\\u000a of the conventional dilute-acid hydrolysis processes, and

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

2004-01-01

91

Two-stage dilute acid prehydrolysis of biomass  

SciTech Connect

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.

Grohmann, Karel (Winter Haven, FL); Torget, Robert W. (Littleton, CO)

1992-01-01

92

Neutralization of sulfuric acid aerosol by ammonia  

Microsoft Academic Search

The rate of neutralization of sulfuric acid aerosol by ammonia gas has been measured in a laboratory flow reactor for particle diameters between 0.3 and 1.4 micrometers and for relative humidities between 8 and 80%. The rates were between 21 and 70% of the rates expected if diffusion of NH to the aerosol droplets was the rate-determining factor, and the

James J. Huntzicker; Robert A. Cary; Chaur-Sun. Ling

1980-01-01

93

Thermodynamics of electrolytes. 7. Sulfuric acid  

Microsoft Academic Search

Although the thermodynamic properties of sulfuric acid above 0.1 M and near 25°C are well established numerically, they have not been represented accurately by equations which are based upon the ionic species present, H\\/sup +\\/, HSO⁻, and SO\\/sup 2 -\\/. We have developed and fitted such equations over the range from 0 to 6 M in a system compatible with

Kenneth S. Pitzer; Rabindra N. Roy; Leonard F. Silvester

1977-01-01

94

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

PubMed

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 9.060.13 mg kg(-1). No statistically significant difference at a 95% confidence level was observed between the measured and certified values for certified reference materials NIST SRM 2773 B100 Biodiesel (Animal-Based), CENAM DRM 272b and NIST SRM 2723a Sulfur in Diesel Fuel Oil, validating method accuracy. PMID:24331043

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

2014-01-01

95

USING ISOTOPE DILUTION MASS SPECTROMETRY TO DETERMINE AQUEOUS TRICHLOROACETIC ACID  

EPA Science Inventory

The development, verification, and application of a method based on isotope dilution gas chromatography-mass spectrometry to determine aqueous trichloroacetic acid (TCAA) at the micrograms per litre level are described. The simultaneous determination of aqueous chloroform is also...

96

Radiolysis of sulfuric acid, sulfuric acid monohydrate, and sulfuric acid tetrahydrate and its relevance to Europa  

Microsoft Academic Search

We studied stability of three acid hydrates during ion irradiation in Europa-like conditions. Using infrared spectroscopy, we identify the main radiation products as H 2 O, SO 2 , (S 2 O 3 ) x , H 3 O + , HSO 4 - , and SO 4 2 - . We find that at higher irradiation temperatures, the more

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

2011-01-01

97

Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium  

ERIC Educational Resources Information Center

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

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

2005-01-01

98

Design and performance of a laboratory sulfuric acid generator  

SciTech Connect

A laboratory sulfuric acid (H/sub 2/SO/sub 4/) generator was designed and constructed to simulate sulfur gas levels in combustion gases. The acid generator produces SO/sub 3/ by the catalytic (platinum-black) oxidation of SO/sub 2/. By controlling the catalyst temperature (20/sup 0/C-538/sup 0/C), a desired SO/sub 3//SO/sub 2/ concentration ratio (30% to 100% conversion of SO/sub 2/ to H/sub 2/SO/sub 4/) can be attained. A separate control system holds moisture at desired levels in the output gas stream. The generator was developed to produce (at output volumes of 1-20 L/min and output temperatures up to 290/sup 0/C) a sustained moisture, SO/sub 2/ and H/sub 2/SO/sub 4/ gas stream, which could serve both as a method development and monitor performance evaluaton tool. The results of an evaluation of the H/sub 2/SO/sub 4/ generator showed that regulated gas stream moisture levels (10.8%-11.3% v/v) were held constant over an extended period of time (168 h). A constant rate of acid could be generated by varying either the SO/sub 2/ dilution or the converter temperature. A purge technique developed during the study decreased the stabilization time required (from 3 h to 30 min) following a converter temperature change.

Walters, C.L.; Cheney, J.L.

1983-10-01

99

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids.  

National Technical Information Service (NTIS)

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/hydroge...

G. W. Cooper M. H. Thiemens S. Chang T. L. Jackson

1997-01-01

100

Economic comparison of hydrogen production using sulfuric acid electrolysis and sulfur cycle water decomposition. Final report  

Microsoft Academic Search

An evaluation of the relative economics of hydrogen production using two advanced techniques was performed. The hydrogen production systems considered were the Westinghouse Sulfur Cycle Water Decomposition System and a water electrolysis system employing a sulfuric acid electrolyte. The former is a hybrid system in which hydrogen is produced in an electrolyzer which uses sulfur dioxide to depolarize the anode.

G. H. Farbman; B. R. Krasicki; C. C. Hardman; S. S. Lin; G. H. Parker

1978-01-01

101

Reactivity Toward Phenol of Lignin from the Hydrolysis of Sweetgum Wood with Concentrated Sulfuric Acid  

Microsoft Academic Search

Sweetgum wood was hydrolyzed at 20C and 50C for different time periods with 68% sulfuric acid. The lignin residues obtained were subjected to a phenolation reaction. For lignin prepared at the lower temperature the maximum phenol uptake was 9.5%, and at the higher temperature only 56%. When wood prehydrolyzed with dilute acid was used the phenol uptake rose to 12.5%.

Durlubh K. Sharma; Irving S. Goldstein

1990-01-01

102

Sulfuric Acid Production on Europa: The Radiolysis of Sulfur in Water Ice  

Microsoft Academic Search

Europa's surface is chemically altered by radiolysis from energetic charged particle bombardment. It has been suggested that hydrated sulfuric acid (H2SO4nH2O) is a major surface species and is part of a radiolytic sulfur cycle, where a dynamic equilibrium exists between continuous production and destruction of sulfur polymers Sx, sulfur dioxide SO2, hydrogen sulfide H2S, and H2SO4nH2O. We measured the rate

R. W. Carlson; M. S. Anderson; R. E. Johnson; M. B. Schulman; A. H. Yavrouian

2002-01-01

103

Sulfuric Acid Production on Europa: The Radiolysis of Sulfur in Water Ice  

Microsoft Academic Search

Europa's surface is chemically altered by radiolysis from energetic charged particle bombardment. It has been suggested that hydrated sulfuric acid (H2SO4.nH2O) is a major surface species and is part of a radiolytic sulfur cycle, where a dynamic equilibrium exists between continuous production and destruction of sulfur polymers Sx, sulfur dioxide SO2, hydrogen sulfide H2S, and H2SO4.nH2O. We measured the rate

R. W. Carlson; M. S. Anderson; R. E. Johnson; M. B. Schulman; A. H. Yavrouian

2002-01-01

104

21 CFR 184.1095 - Sulfuric acid.  

Code of Federal Regulations, 2013 CFR

...sulfur dioxide (SO2 ) with oxygen and mixing the resultant sulfur trioxide (SO3 ) with water, or by reacting nitric oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the specifications of the Food...

2013-04-01

105

High Xylose Yields from Dilute Acid Pretreatment of Corn Stover Under Process-Relevant Conditions  

SciTech Connect

Pretreatment experiments were carried out to demonstrate high xylose yields at high solids loadings in two different batch pretreatment reactors under process-relevant conditions. Corn stover was pretreated with dilute sulfuric acid using a 4-l Steam Digester and a 4-l stirred ZipperClave{reg_sign} reactor. Solids were loaded at 45% dry matter (wt/wt) after sulfuric acid catalyst impregnation using nominal particle sizes of either 6 or 18 mm. Pretreatment was carried out at temperatures between 180 and 200 C at residence times of either 90 or 105 s. Results demonstrate an ability to achieve high xylose yields (>80%) over a range of pretreatment conditions, with performance showing little dependence on particle size or pretreatment reactor type. The high xylose yields are attributed to effective catalyst impregnation and rapid rates of heat transfer during pretreatment.

Weiss, N. D.; Nagle, N. J.; Tucker, M. P.; Elander, R. T.

2009-01-01

106

Growth of nitric acid hydrates on thin sulfuric acid films  

Microsoft Academic Search

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 [times] 10[sup [minus]4] Torr H[sub 2]O and 1-2.5 [times] 10[sup [minus]6] Torr HNO[sub 3]) and subjected to cooling and heating cycles. FTIR spectroscopy was used to

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

1994-01-01

107

SULFURIC ACID RAIN EFFECTS ON CROP YIELD AND FOLIAR INJURY  

EPA Science Inventory

A study was undertaken to determine the relative sensitivity of major U.S. crops to sulfuric acid rain. Plants were grown under controlled environmental conditions and exposed to simulated acid rain of three sulfuric acid concentrations (pH 3.0, 3.5, 4.0) or to a control rain (pH...

108

Two-stage dilute acid prehydrolysis of biomass  

SciTech Connect

The invention relates to a two stage dilute acid prehydrolysis of biomass for solubilization of hemicellulosic sugars and a pretreatment for enzymatic hydrolysis of cellulose. In particular, the invention pertains to a two stage dilute acid prehydrolysis treatment of a feedstock of hemicellulosic material comprising xylan that is slow hydrolyzable and xylan that is fast hydrolyzable under low temperature conditions to hydrolyze said fast hydrolyzable xylan to xylose; removing said xylose and leaving a feedstock residue containing said slow hydrolyzable xylan; treating said residue containing said slow hydrolyzable xylan with a dilute organic or inorganic acid under temperature conditions higher than said low temperature conditions to hydrolyze said slow hydrolyzable xylan to xylose, and removing said xylose.

Grohmann, K.; Torget, R.W.

1991-04-08

109

Heterogeneous Interactions of Acetaldehyde and Sulfuric Acid  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

110

Chemical and microbiological tests to simulate sulfuric acid corrosion of polymer-modified concrete  

Microsoft Academic Search

In certain industrial activities sulfuric acid is used during the production process, which may cause degradation of concrete structures. Another important phenomenon where sulfuric acid is responsible for concrete corrosion is biogenic sulfuric acid corrosion, which occurs often in sewer systems. Because previous investigations have already pointed out the difference between purely chemical sulfuric acid corrosion and biogenic sulfuric acid

J Monteny; N De Belie; E Vincke; W Verstraete; L Taerwe

2001-01-01

111

Sulfuric acid leaching of ocean manganese nodules using phenols as reducing agents  

Microsoft Academic Search

Pacific Ocean manganese nodule samples were leached with dilute sulfuric acid in the presence of phenol type aromatic reducing agents. Six phenols, including hydroxybenzene, o-dihydroxybenzene, m-dihydroxybenzene, p-dihydroxybenzene, o-trihydroxybenzene and m-trihydroxybenzene, were tested. The results indicated that all the tested phenols were effective reducing agents that significantly increased the extraction of Mn, Cu, Ni, Co from the nodules. At a dosage

Yahui Zhang; Qi Liu; Chuanyao Sun

2001-01-01

112

GENERATION OF SULFURIC ACID AEROSOLS FOR HEALTH EFFECT STUDIES  

EPA Science Inventory

A generator has been developed and constructed for producing sulfuric acid aerosols at 330 liters per minute to an animal exposure chamber of 330 liters internal volume. Sulfuric acid concentrations in the chamber range from 0.13 to 1.3 mg/cu m. Geometrical mean volume diameters ...

113

RESISTANCE OF FLY ASH BASED GEOPOLYMER MORTARS IN SULFURIC ACID  

Microsoft Academic Search

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

Suresh Thokchom; Partha Ghosh; Somnath Ghosh

114

COMPARISON OF AUTOMATED AND MANUAL SULFURIC ACID SAMPLING SYSTEMS  

EPA Science Inventory

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

115

Sulfur removal from original and acid treated lignites by pyrolysis  

Microsoft Academic Search

Six original, three hydrochloric acid treated and three demineralized lignite samples were pyrolysed at seven different temperatures between 350 and 950C for 7min under evolved gas atmosphere. All samples and their chars were analysed quantitatively for their total sulfur content and pyritic, sulfate and organic sulfur forms. The alkaline oxide contents of original lignites and their hydrochloric acid treated counterparts

Davut Uzun; Sibel zdo?an

2006-01-01

116

Solubility of HCL in sulfuric acid at stratospheric temperatures  

NASA Technical Reports Server (NTRS)

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.

Williams, Leah R.; Golden, David M.

1993-01-01

117

Ethanol production with dilute acid hydrolysis using partially dried lignocellulosics  

DOEpatents

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.

Nguyen, Quang A. (Chesterfield, MO); Keller, Fred A. (Lakewood, CO); Tucker, Melvin P. (Lakewood, CO)

2003-12-09

118

Certain Organic Corrosion Inhibitors for Titanium in Sulfuric Acid. Ii.  

National Technical Information Service (NTIS)

The corrosive and electrochemical behavior of titanium was studied in 5 N sulfuric acid solutions with admixtures of para-, meta- and orthonitrobenzoic acids. It is shown that these admixtures, like other nitro derivatives, inhibit the corrosion of titani...

A. P. Brynza V. I. Sotnikova T. A. Ponomarenko

1969-01-01

119

Potential Heat Exchange Fluids for Use in Sulfuric Acid Vaporizers.  

National Technical Information Service (NTIS)

A series of liquids have been screened 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 physi...

D. D. Lawson G. R. Petersen

1979-01-01

120

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

121

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

Code of Federal Regulations, 2010 CFR

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

2009-10-01

122

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

123

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

124

Processing of the Pyrite Concentrates to Generate Sulfurous Anhydride for Sulfuric Acid Production  

Microsoft Academic Search

The results of two-stage roasting of pyrite concentrate with air blowing and the principle scheme of the process are presented in the report. The results of experimental sulfuric acid production tests using pyrite concentrate to generate sulfurous rich gas containing 0.1 - 0.15% of sulphur trioxide are shown. Comparative characteristics with technologies known for the present are given.

T. A. Chepushtanova; V. A. Luganov

125

Dilute-acid hydrolysis of sugarcane bagasse at varying conditions  

Microsoft Academic Search

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

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

2002-01-01

126

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Astrophysics Data System (ADS)

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.

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

1997-08-01

127

Sulfur and hydrogen isotope anomalies in meteorite sulfonic acids.  

PubMed

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. PMID:9262469

Cooper, G W; Thiemens, M H; Jackson, T L; Chang, S

1997-08-22

128

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

129

Temperature dependency of single-bubble sonoluminescence in sulfuric acid  

NASA Astrophysics Data System (ADS)

Using a hydrochemical simulation, temperature dependency of single-bubble sonoluminescence (SL) in a concentrated solution of sulfuric acid has theoretically been studied. With calculating the phase diagrams of an SL bubble in the solution of 85% acid, maximum acquirable SL emissions at different ambient temperatures were calculated. The results show that the SL emission in sulfuric acid increases with increment in the ambient temperature. This temperature dependency is in opposition to that observed in experiments for SL in water. The difference originates from different instability mechanisms determining the ultimate phase parameters of SL in water and sulfuric acid. In water, due to the smallness of viscosity, the ultimate phase parameters are determined by the shape instability. However, in sulfuric acid the phase parameters are restricted by positional instability due to the largeness of the liquid viscosity.

Moshaii, A.; Tajik-Nezhad, S.; Faraji, M.

2011-10-01

130

Temperature dependency of single-bubble sonoluminescence in sulfuric acid.  

PubMed

Using a hydrochemical simulation, temperature dependency of single-bubble sonoluminescence (SL) in a concentrated solution of sulfuric acid has theoretically been studied. With calculating the phase diagrams of an SL bubble in the solution of 85% acid, maximum acquirable SL emissions at different ambient temperatures were calculated. The results show that the SL emission in sulfuric acid increases with increment in the ambient temperature. This temperature dependency is in opposition to that observed in experiments for SL in water. The difference originates from different instability mechanisms determining the ultimate phase parameters of SL in water and sulfuric acid. In water, due to the smallness of viscosity, the ultimate phase parameters are determined by the shape instability. However, in sulfuric acid the phase parameters are restricted by positional instability due to the largeness of the liquid viscosity. PMID:22181255

Moshaii, A; Tajik-Nezhad, S; Faraji, M

2011-10-01

131

Determination of Sulfur Trioxide in Oleum/Nitric Acid Mixtures.  

National Technical Information Service (NTIS)

A method of analysis is described for determination of the sulfur trioxide content of oleum/nitric acid mixtures found in the low temperature continuous TNT process. This method consists of the indirect determination of sulfur trioxide, via the water cons...

R. Manno C. Ribaudo

1974-01-01

132

DEVELOPMENT OF A PORTABLE DEVICE TO COLLECT SULFURIC ACID AEROSOL  

EPA Science Inventory

A quantitative, interference-free method for collecting sulfuric acid aerosol on a filter was developed and field tested. Since previous research found that severe losses of sulfuric aicd were caused by ammonia, ambient particulate material, and other interferents, a method was n...

133

Compact regenerable sulfur scrubber for phosphoric acid fuel cells  

NASA Astrophysics Data System (ADS)

Technology for the direct desulfurization of unprocessed diesel fuel using regenerable copper-based mixed metal oxide sorbents was developed for incorporation in modular phosphoric acid fuel cell (PAFC) generators. Removal of greater than 60 percent of the sulfur in diesel fuel was demonstrated, and sorbent sulfur loadings of approximately 1 wt percent were attained. Preliminary studies indicated that the sorbents are regenerable, with up to 70 percent of the sorbed sulfur removed during regeneration. Incorporation of this technology into a PAFC power plant should reduce the weight of the sulfur removal unit by a minimum of 25 percent.

Giner, Jose; Cropley, Cecelia C.

1987-11-01

134

Breakdown of cell wall nanostructure in dilute acid pretreated biomass.  

PubMed

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

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

2010-09-13

135

Breakdown of Cell Wall Nanostructure in Dilute Acid Pretreated Biomass  

SciTech Connect

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

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

2010-01-01

136

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

Code of Federal Regulations, 2010 CFR

...substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220...substituted benzenesulfonic acid and sulfuric acid (generic name). (a) Chemical...substituted benzenesulfonic acid and sulfuric acid (PMNs P-89-703,...

2009-07-01

137

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

Code of Federal Regulations, 2010 CFR

...substituted benzenesulfonic acid and sulfuric acid (generic name). 721.9220...substituted benzenesulfonic acid and sulfuric acid (generic name). (a) Chemical...substituted benzenesulfonic acid and sulfuric acid (PMNs P-89-703,...

2010-07-01

138

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

PubMed

In the present study, combined steam (140-180C) 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 180C 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. PMID:24821202

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

2014-07-01

139

Early diagenesis of sulfur in estuarine sediments: the role of sedimentary humic and fulvic acids  

NASA Astrophysics Data System (ADS)

Sediments were collected from anoxic, organic-rich estuarine muds of St. Andrew Bay, Florida to assess the early diagenetic pathways leading to the formation of organic and inorganic sedimentary sulfide species. Abundance and sulfur isotopic composition were determined for dissolved sulfide, dissolved sulfate, elemental sulfur, acid-volatile sulfide, chromium-reducible sulfur, fulvic acid-sulfur, humic acid-sulfur, and residual organic (protokerogen) sulfur. Fulvic acid-sulfur, elemental sulfur, and acid-volatile sulfides are the initial sinks for dissolved sulfide and form before pyrite. Subsequently, two-thirds of fulvic acid-sulfur are lost. A fraction of fulvic acid-sulfur is transferred to higher molecular weight compounds such as humic acids and protokerogens, but most of the sulfides are recycled back to the porewaters. Enrichments in the isotopic composition of organic sulfur fractions, relative to pyrite and acid-volatile sulfides, suggest a contribution of detrital biosynthetic sulfur to the organic sulfur pool. Accounting for the biosynthetic component in fulvic acid-sulfur, the isotopic similarities between elemental sulfur, acid-volatile sulfides, and fulvic acid-sulfur suggest isotopic exchange in the uppermost 3 cm of sediment. Isotopic mass calculations suggest an additional isotopic fractionation takes place during recycling of sulfide released from fulvic acids and elemental sulfur by bacterial disproportionation of polysulfides and elemental sulfur. Subsequent precipitation of recycled, 34S-depleted sulfide as pyrite reconciles the consistent depletion in 34S of pyrite-S relative to all other sedimentary sulfide species.

Brchert, Volker

1998-05-01

140

Interaction of two oscillating sonoluminescence bubbles in sulfuric acid.  

PubMed

The mutual interaction of two oscillating gas bubbles in different concentrations of sulfuric acid is numerically investigated. A nonlinear oscillation for spherical symmetric bubbles with equilibrium radii smaller than 10 ?m at a frequency of 37 kHz in a strong driving acoustical field P(a)=1.8 bar is assumed. The calculations are based on the investigation of the secondary Bjerknes force with regard to adiabatic model for the bubble interior which appears as repulsion or attraction interaction force. In this work the influence of the various concentrations of sulfuric acid in uncoupled and coupled distances between bubbles has been investigated. It is found that the sign and value of the secondary Bjerknes force depend on the sulfuric acid viscosity and its amount would be decreased by liquid viscosity enhancement. The results show that big change in the parameters of produced bubbles occurs in the sulfuric acid with concentrations from 65% to 85%. PMID:20866734

Sadighi-Bonabi, Rasoul; Rezaee, Nastaran; Ebrahimi, Homa; Mirheydari, Mona

2010-07-01

141

Interaction of two oscillating sonoluminescence bubbles in sulfuric acid  

NASA Astrophysics Data System (ADS)

The mutual interaction of two oscillating gas bubbles in different concentrations of sulfuric acid is numerically investigated. A nonlinear oscillation for spherical symmetric bubbles with equilibrium radii smaller than 10?m at a frequency of 37 kHz in a strong driving acoustical field Pa=1.8bar is assumed. The calculations are based on the investigation of the secondary Bjerknes force with regard to adiabatic model for the bubble interior which appears as repulsion or attraction interaction force. In this work the influence of the various concentrations of sulfuric acid in uncoupled and coupled distances between bubbles has been investigated. It is found that the sign and value of the secondary Bjerknes force depend on the sulfuric acid viscosity and its amount would be decreased by liquid viscosity enhancement. The results show that big change in the parameters of produced bubbles occurs in the sulfuric acid with concentrations from 65% to 85%.

Sadighi-Bonabi, Rasoul; Rezaee, Nastaran; Ebrahimi, Homa; Mirheydari, Mona

2010-07-01

142

Uptake kinetics of three epoxides into sulfuric acid solution  

NASA Astrophysics Data System (ADS)

This work presents a study of the uptake of isoprene epoxide, butadiene epoxide (BMO) and butadiene diepoxide (BDO) into sulfuric acid solutions which helps to understand the reactivity of epoxides existing in the atmosphere toward acidic aerosols. The uptake of these three compounds into 0-30 wt % H2SO4 solutions were measured using a rotated wetted-wall reactor (RWW) coupled to a single-photon ionization time of flight mass spectrometer (SPI-TOFMS). The epoxides were found to be very easily taken up by H2SO4 solutions even in dilute concentrations of pH levels. Isoprene epoxide was found to partition reversibly into solution at pH = 4, whereas irreversible uptake was observed when pH ? 3. We reported the reactive uptake coefficients from 1.87 10-5 to 2.67 10-3 for pH = 3-20 wt % H2SO4 solutions. A chemical reaction for isoprene epoxide was responsible for the reactive uptake. By means of mass spectrometry, gas chromatography and FTIR spectroscopy, a gas product was identified to be 2-methyl-3-butenal. The uptake behavior of butadiene epoxide was similar with that of isoprene epoxide, while butadiene diepoxide partitioned irreversibly over the whole acidity range of 0-30 wt %, and the reactive uptake coefficients increased slightly (0.849 10-4-1.36 10-4) from pure water to pH = 1. The reactivity that displayed close dependence on the hydrolysis rates of the three epoxides was analyzed and compared according to their molecular structural differences. The atmospheric lifetimes were calculated and atmospheric implication was discussed based on the corresponding reactive uptake coefficients.

Wang, Tianhe; Liu, Ze; Wang, Weigang; Ge, Maofa

2012-09-01

143

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

NASA Technical Reports Server (NTRS)

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.

Danford, M. D.

1994-01-01

144

Shakedown operations in commercial production of sulfuric acid from acid tar  

Microsoft Academic Search

The authors describe process technology for processing acid tars to obtain sulfuric acid by means of high temperature splitting to regenerate spent sulfuric acid contaminated with organic impurities. An illustration presents a simplified flow plan for acid tar processing. The authors conclude, from experience with this unit, that process indexes meet design requirements, in particular with respect to the degree

V. M. Perfilev; V. B. Golyshev; A. D. Goncharenko; A. M. Shtafinskaya; V. S. Sushchev

1985-01-01

145

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

NASA Astrophysics Data System (ADS)

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 90C, 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.

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

2011-08-01

146

Collaborative Study of Method for the Determination of Sulfuric Acid Mist and Sulfur Dioxide Emissions from Stationary Sources.  

National Technical Information Service (NTIS)

Statistical analyses are performed on data obtained in collaborative testing of EPA Method 8 (Determination of Sulfuric Acid Mist and Sulfur Dioxide Emissions From Stationary Sources) and from ancillary tests performed in conjunction with the analysis of ...

D. E. Camann H. F. Hamil R. E. Thomas

1974-01-01

147

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

ERIC Educational Resources Information Center

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)

Raw, C. J. G.; And Others

1983-01-01

148

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

149

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

150

Comparison of microbial sulfuric acid production in sewage sludge from added sulfur and thiosulfate  

SciTech Connect

Microbial leaching is one of the most attractive methods of removing toxic metals from sewage sludge. Sulfuric acid produced by indigenous microflora by the oxidation of elemental sulfur and sulfur compounds solubilizes toxic metals. The oxidation of sulfur compounds can be achieved by the direct oxidation to sulfates or by indirect oxidation, through the production and accumulation of soluble intermediate S{sub 2}O{sub 3}{sup 2}{sup -}, S{sub 3}O{sup 6}{sup 2}{sup -}, S{sub 4}O{sub 6}{sup 2}{sup -} compounds. The production of these intermediates may create a potential danger of acidification of the receiving waters or the agricultural soil where the leached sludge is ultimately destined, via slow oxidation of the intermediates with subsequent sulfuric acid production. The objective of this research was to investigate the formation of S{sub 2}O{sub 3}{sup 2}{sup -}, S{sub 3}O{sub 6}{sup 2}{sup -}, and S{sub 4}O{sub 6}{sup 2} during metal bioleaching using elemental sulfur and thiosulfate as energy substrates for growth of indigenous thiobacilli (sulfur-oxidizing microorganisms) in sludge. The results obtained showed that intermediates were not formed when elemental sulfur was used as a substrate, whereas trithionate and tetrathionate and tetrathionate accumulated in the sludges when thiosulfate was used as substrate. Moreover, the metabolism of thiosulfate was much slower than that of elemental sulfur in sludge medium. Therefore, the utilization of thiosulfate for the growth of indigenous thiobacilli in sewage sludge is a less attractive alternative for the metal bioleaching. 33 refs., 3 figs., 2 tabs.

Tyagi, R.D.; Blais, J.F.; Deschenes, L. [Universite du Quebec (Canada)

1994-09-01

151

Photometric determination of sulfuric acid in ammonium sulfate  

SciTech Connect

A method of determining the concentration of sulfuric acid in ammonium sulfate was outlined. Due to the unfavorable effects sulfuric acid has in fertilizers, Soviet industry limits the concentration to 0.025-0.050 wt. % H/sub 2/SO/sub 4/ in ammonium sulfate. The method developed by the authors was based on the optical density of an acid-base indicator in the presence of an acid. The indicator used in the experiments was 2,5-dinitrophenol. The accuracy of this method compared favorably to the more commonly used titration method. (JMT)

Yakovleva, T.P.; Privalova, N.V.; Tsebrii, L.S.; Vail, E.I.

1982-01-01

152

Cellulase Accessibility of Dilute-Acid Pretreated Corn Stover  

SciTech Connect

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.

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

2005-01-01

153

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

NASA Astrophysics Data System (ADS)

Few measurements of H2SO4 vapor pressure have been made for sulfuric acid in the temperature and concentration ranges of atmospheric interest because of the very low pressures involved (below 10-4 Pa, or 10-6 torr); no such measurements appear to have been made for sulfuric acid solutions neutralized with ammonia. This work presents measurements of H2SO4 vapor pressure for aqueous sulfuric acid solutions between 55 and 77 wt% H2SO4 (corresponding to about 5-25% relative humidity), ammonium sulfate solids at low humidities, and partially neutralized sulfate solutions with [NH4+]: [SO4=] ratios between 0.13 and 1.0. The vapor pressure data collected over sulfuric acid solutions generally agree with the predictions of Ayers, et al. [1980], although positive deviation was observed for the more dilute solutions. The good agreement between this measurement and previous efforts by absolute techniques suggests that the evaporative coefficient for the H2SO4-H2O system is near unity. H2SO4 vapor pressures over solid ammonium sulfate were measured between 27C and 60C; the data were fitted to In p = A/T + B, with A = -5928 and B = -3.77. The H2SO4 vapor pressures of mixed H2SO4-H2O-(NH4)2SO4 solutions dropped significantly as the [NH4+]:[SO4=] ratio exceeded 0.5. The results suggest that ammonia could very effectively stabilize molecular clusters of sulfuric acid and water in the atmosphere against evaporation, leading to rates of new particle formation higher than those predicted by binary H2SO4-H2O theory.

Marti, James J.; Jefferson, Anne; Cai, Xiao Ping; Richert, Chad; McMurry, Peter H.; Eisele, Fred

1997-02-01

154

EVALUATION OF METHODOLOGY AND PROTOTYPE TO MEASURE ATMOSPHERIC SULFURIC ACID  

EPA Science Inventory

A method is being developed to selectively assay ambient sulfuric acid aerosol. The method utilizes the vapor of a volatile amine (or amine derivative) to neutralize the acid as it is collected on a Teflon filter. The amine sulfate thus formed is thermally decomposed at 200C to r...

155

Potential heat exchange fluids for use in sulfuric acid vaporizers  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

156

MOLECULAR SIEVE TESTS FOR CONTROL OF SULFURIC ACID PLANT EMISSIONS  

EPA Science Inventory

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

157

Recovery of selenium sludges in sulfuric acid production  

Microsoft Academic Search

Most of the selenium compounds formed in the production of sulfuric acid when roasting pyrites is sent together with the roaster gas and residues of cinder dust to the equipment in the wash division. Recovery of these sludges from the wash acid is the subject discussed in the present report. Analysis of the total variety of aspects related to the

V. S. Epifanov; G. B. Kabanova; L. V. Konyakhina; V. G. Moshkova; V. P. Syskova

1983-01-01

158

Characterization of sulfurous acid, sulfite, and bisulfite aerosol systems.  

PubMed

Acidic tropospheric aerosols contain inorganic species such as sulfurous acid (H(2)SO(3)). As the main alkaline species, ammonia (NH(3)) plays an important role in the heterogeneous neutralization of these acidic aerosols. An aerosol flow-tube apparatus was used to obtain simultaneous optical and size distribution measurements using FTIR and SMPS measurements, respectively, as a function of relative humidity and aerosol chemical composition. A novel chemiluminescence apparatus was also used to measure ammonium ion concentration [NH(4)(+)]. The interactions between ammonia and hydrated sulfur dioxide (SO(2)H(2)O) were studied at different humidities and concentrations. SO(2)H(2)O is an important species as it represents the first intermediate in the overall atmospheric oxidation process of sulfur dioxide to sulfuric acid (H(2)SO(4)). This complex was produced within gaseous, aqueous, and aerosol SO(2) systems. The addition of ammonia gave mainly hydrogen sulfite (SHO(3)(-)) tautomers and disulfite ions (S(2)O(5)(2-)). These species were prevalent at high humidities enhancing the aqueous nature of sulfur(IV) species. Their weak acidity is evident due to the low [NH(4)(+)] produced. Size distributions obtained correlated well with the various stages of particulate compositional development. PMID:22471624

Townsend, Thomas M; Allanic, Arnaud; Noonan, Colette; Sodeau, John R

2012-04-26

159

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

SciTech Connect

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.

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

2005-09-01

160

Composition of acid tars from sulfuric acid treatment of petroleum oils  

Microsoft Academic Search

In the production of distillate and residual lube oils, the lube stocks may be treated with concentrated sulfuric acid or oleum. This removes unsaturates, aromatics, sulfur compounds, nitrogen compounds and resinous substances, all of which are materials that lower the stability and have a detrimental effect on the service indexes of commercial petroleum oils. Acid tar is formed as a

A. F. Frolov; T. S. Titova; I. V. Karpova; T. L. Denisova

1985-01-01

161

Sulfur-Containing Amino Acid Metabolism in Parasitic Protozoa  

Microsoft Academic Search

Sulfur-containing amino acids play indispensable roles in a wide variety of biological activities including protein synthesis, methylation, and biosynthesis of polyamines and glutathione. Biosynthesis and catabolism of these amino acids need to be carefully regulated to achieve the requirement of the above-mentioned activities and also to eliminate toxicity attributable to the amino acids. Genome-wide analyses of enzymes involved in the

Tomoyoshi Nozaki; Vahab Ali; Masaharu Tokoro

2005-01-01

162

Effect of Water Transport on the Production of Hydrogen and Sulfuric Acid in a PEM Electrolyzer  

Microsoft Academic Search

The thermochemical cycle involving the interconversion between sulfur dioxide and sulfuric acid is a promising method for efficient, large-scale production of hydrogen. A key step in the process is the oxidation of sulfur dioxide to sulfuric acid in an electrolyzer. Gaseous SO2 fed to a proton exchange membrane PEM electrolyzer was previously investigated and was shown to be a promising

John A. Staser; John W. Weidner

2009-01-01

163

Dilute acid hemicellulose hydrolysates from corn cobs for xylitol production by yeast  

Microsoft Academic Search

Dilute acid hemicellulose hydrolysate, comprised mainly of xylose, was obtained from ground corn cobs after dilute hydrochloric acid (2%, wt) hydrolysis at 100C for 2 h. Similar acid hydrolysate was also obtained after the corn cobs were treated with 10% ammonium hydroxide at 26C for 24 h. Neutralized hydrolysates containing ca. 130 g\\/l xylose were used as the substrate for

Jose M. Dominguez; Ningjun Cao; C. S. Gong; G. T. Tsao

1997-01-01

164

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)

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 ??CO2 = 3.3 +/- 1.8% and ??T = 2.9 +/- 1.6% for fuel sulfur conversion to sulfuric acid were inferred when relating the H2SO4 data to measurements of the plume tracers ?CO2 and ?T.

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

2002-04-01

165

UV photolysis of perfluorooctanoic acid (PFOA) in dilute aqueous solution.  

PubMed

Perfluorooctanoic acid (PFOA) is very persistent in the environment and widely detected in the water environment. Only some advanced methods with extreme reaction conditions are shown to be capable of degrading the compound efficiently, and almost all the earlier investigations used very high PFOA concentrations. The compound is detected normally at very low concentrations in the water environment, while mild reaction conditions for its degradation are preferable. This article aimed to elucidate photodegradation of PFOA in dilute aqueous solutions by combined UV wavelengths (185 nm+254 nm) and 254 nm using a newly designed UV jacket. PFOA degradation was greatly enhanced with the combined wavelengths with almost one hundred percent PFOA removals in four-hour reaction. The removals were well described by the first-order reaction kinetic. The removal efficiencies and rate values significantly decreased with smaller initial PFOA concentrations. But defluorination was greatly enhanced with smaller PFOA concentrations possibly due to accelerated decomposition of fluorinated intermediates of PFOA. Formic acid and acetic acid were two tentatively identified intermediates of PFOA photolysis while the former was a major intermediate predominantly controlling solution pH during the oxidation. The results demonstrated that PFOA photolysis by the combined wavelengths with mild reaction conditions can be greatly enhanced by proper design of UV jacket and reactor system. PMID:21252431

Giri, R R; Ozaki, H; Morigaki, T; Taniguchi, S; Takanami, R

2011-01-01

166

Pt\\/TiO 2 (rutile) catalysts for sulfuric acid decomposition in sulfur-based thermochemical water-splitting cycles  

Microsoft Academic Search

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 1wt% Pt\\/TiO2 (rutile) catalysts submitted to flowing concentrated sulfuric acid at 1123K and atmospheric pressure for different times

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

2008-01-01

167

Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

168

Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

169

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...

170

A TUNABLE DIODE LASER STACK MONITOR FOR SULFURIC ACID VAPOR  

EPA Science Inventory

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

171

Effects of Sulfuric Acid Mist Exposure on Pulmonary Function.  

National Technical Information Service (NTIS)

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

S. M. Horvath L. J. Folinsbee J. F. Bedi

1981-01-01

172

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

EPA Science Inventory

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

173

Electropolishing of tantalum in sulfuric acidmethanol electrolytes  

Microsoft Academic Search

The electropolishing of tantalum in sulfuric acidmethanol electrolytes is studied by steady state measurements and ac impedance spectroscopy using a rotating disk electrode. The effects of electrolyte composition, applied potential, electrode rotation rate and temperature on the response of the system are investigated. Steady state measurements performed at different temperatures show that at the limiting current plateau the rate of

O Piotrowski; C Madore; D Landolt

1999-01-01

174

Parameterizations for sulfuric acid\\/water nucleation rates  

Microsoft Academic Search

We present parametrized equations for calculation of sulfuric acid\\/water critical nucleus compositions and homogeneous nucleation rates. The parameterizations are in agreement with the thermodynamically consistent version of classical binary homogeneous nucleation theory [Wilemski, 1984] incorporating the hydration effect. The new parameterizations produce nucleation rates that differ by several orders of magnitude from the rates predicted by other parameterizations available in

Markku Kulmala; Ari Laaksonen; Liisa Pirjola

1998-01-01

175

Extraction of phenol by sulfuric acid salts of trioctylamine  

Microsoft Academic Search

The extraction of phenol from an aqueous solution using sulfuric acid salts of trioctylamine (TOA salts) was carried out. Trioctylamine (TOA) dissolved in diisopropyl ether (DIPE) (or 1?octanol, cyclohex?ane, benzene and kerosene) was evaluated for extraction of phenol at various volume ratios of organic phase to aqueous phase at varied temperatures. The equilibrium distribution coefficient (KD) for the extraction of

1995-01-01

176

Potential heat exchange fluids for use in sulfuric acid vaporizers  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

177

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

Code of Federal Regulations, 2010 CFR

...tolerance. (a) Residues of sulfuric acid are exempted from the...used as a herbicide in the production of garlic and onions...potato vine dessicant in the production of potatoes. (b) Residues of sulfuric acid are exempted from...

2009-07-01

178

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

Code of Federal Regulations, 2010 CFR

...tolerance. (a) Residues of sulfuric acid are exempted from the...used as a herbicide in the production of garlic and onions...potato vine dessicant in the production of potatoes. (b) Residues of sulfuric acid are exempted from...

2010-07-01

179

Nature of niobium passivation in hydrofluoric-sulfuric acid baths  

SciTech Connect

The authors investigate the growth, dissolution, thickness, and phase behavior of niobium oxide passivating films on the surface of niobium during electrochemical polishing and oxidation of the metal in hydrofluoric and sulfuric acid solutions. The dependence of the film properties on the concentration of acids in the solution was determined in order to optimize process control conditions for passivation and polishing procedures. Laser interferometry and oscillography were used to examine the film.

Eidel'berg, M.I.; Sandulov, D.B.

1987-10-01

180

Regulation of Sulfur Amino Acid Metabolism in Men in Response to Changes in Sulfur Amino Acid Intakes1,2  

Microsoft Academic Search

We showed previously that 64% of the total dietary sulfur amino acid (SAA) requirement could be supported by dietary cysteine (Cys). However, the observation of such a sparing effect may be affected by the dietary intakes of SAA provided. The aim of this study was to compare methionine (Met) metabolism and transsulfuration (TS) in five healthy men fed three different

Marco Di Buono; Linda J. Wykes; David E. C. Cole; Ronald O. Ball; Paul B. Pencharz

181

Sulfuric acid aerosols and HCl release in coastal atmospheres: evidence of rapid formation of sulfuric acid particulates  

Microsoft Academic Search

Research report:Bacteriogenic sulfide sources may contribute to atmospheric loads of particulate sulfate in coastal locations where bacteriogenic hydrogen sulfide is released to the atmosphere. Studies were conducted along the North Carolina coast to determine the origins and chemical properties of such sulfates and to observe sulfuric acid volatization. Excess sulfate was found in all samples and strongly associated with loss

D. R. Hitchcock; L. L. Spiller; W. E. Wilson

1980-01-01

182

Freezing nucleation of levitated single sulfuric acid/H 2O micro-droplets. A combined Raman- and Mie spectroscopic study  

NASA Astrophysics Data System (ADS)

The phase behaviour of single sulfuric acid/H 2O micro-droplets upon supercooling has been studied using optical levitation of such droplets in combination with Raman- and Mie spectroscopy for chemical and size analysis. It is found that the freezing nucleation behaviour depends on the sulfuric acid concentration of the droplets and hence the region of the phase diagram which is reached upon cooling. Whereas for diluted droplets (c H2SO4<30 wt%) instantaneous ice nucleation is observed, more concentrated droplets tend to supercool with no tendency to nucleate the thermodynamically stable hydrate phase sulfuric acid tetrahydrate (SAT) or sulfuric acid monohydrate (SAM). The upper limits of the nucleation rate in this regime were determined to be J?510 5 cm -3 s -1.

Mund, C.; Zellner, R.

2003-12-01

183

Stability of supported platinum sulfuric acid decomposition catalysts for use in thermochemical water splitting cycles  

Microsoft Academic Search

The activity and stability of several metal oxide supported platinum catalysts were explored for the sulfuric acid decomposition reaction. The acid decomposition reaction is common to several sulfur based thermochemical water splitting cycles. Reactions were carried out using a feed of concentrated liquid sulfuric acid (96wt%) at atmospheric pressure at temperatures between 800 and 850?C and a weight hour space

Daniel M. Ginosar; Lucia M. Petkovic; Anne W. Glenn; Kyle C. Burch

2007-01-01

184

MODEL OF CHEMICAL REACTION EQUILIBRIUM OF SULFURIC ACID SALTS OF TRIOCTYLAMINE  

Microsoft Academic Search

The chemical reaction of trioctylamine (TOA) and sulfuric acid in organic solvent\\/aqueous solution was carried out. TOA salt products of various kinds were obtained based on different conditions of operation and organic solvents. An equilibrium model, based on the chemical reaction of sulfuric acid and trioctylamine, is proposed. The equilibrium constants of various reactions of trioctylamine and sulfuric acid were

MAW-LING WANG; KWAN-HUA HU

1993-01-01

185

Reactivity of BrONO2 and HOBr on sulfuric acid solutions at low temperatures  

Microsoft Academic Search

Uptake of BrONO2 onto bulk sulfuric acid solutions and submicron sulfuric acid aerosol particles was studied in laminar flow cylindrical reactors where a chemical ionization mass spectrometer was used to detect products and reactants. Results from measurements at low temperatures and for sulfuric acid content between 70 and 85 wt.% are presented. These measurements suggest that the reaction probability for

D. R. Hanson

2003-01-01

186

Design and analysis of a high pressure and high temperature sulfuric acid experimental system  

Microsoft Academic Search

We discuss the design and analysis of a small scale sulfuric acid experimental system that can simulate a part of the hydrogen production module. Because nuclear hydrogen coupled components such as a SO3 decomposer and a sulfuric acid evaporator should be tested under high pressure and high temperature operating conditions, we developed the sulfuric acid loop to satisfy design specifications

Sung-Deok Hong; Chan-Soo Kim; Yong-Wan Kim; Dong-Un Seo; Goon-Cherl Park

187

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

SciTech Connect

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.

Gary M. Blythe

2000-12-01

188

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

Microsoft Academic Search

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

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

2011-01-01

189

Refining of oxidation product without alkali and sulfuric acid in the manufacture of synthetic fatty acids  

Microsoft Academic Search

In the existing technology, the free and esterified fatty acids are saponified and converted into the sodium salts by treating them first with calcined and then with caustic soda. After the primary and secondary nonsaponifiable substances have been removed, the sodium salts in the soap paste are decomposed with sulfuric acid, so that the acids are liberated. The free acids

P. A. Moshkin; N. B. Rapoport; M. A. Soskin

1965-01-01

190

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

NASA Astrophysics Data System (ADS)

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

Olenius, T.; Kupiainen-Mtt, O.; Ortega, I. K.; Kurtn, T.; Vehkamki, H.

2013-08-01

191

Evaluation of continuous ethanol fermentation of dilute-acid corn stover hydrolysate using thermophilic anaerobic bacterium Thermoanaerobacter BG1L1  

Microsoft Academic Search

Dilute sulfuric acid pretreated corn stover is potential feedstock of industrial interest for second generation fuel ethanol\\u000a production. However, the toxicity of corn stover hydrolysate (PCS) has been a challenge for fermentation by recombinant xylose\\u000a fermenting organisms. In this work, the thermophilic anaerobic bacterial strain Thermoanaerobacter BG1L1 was assessed for its ability to ferment undetoxified PCS hydrolysate in a continuous

Tania I. Georgieva; Birgitte K. Ahring

2007-01-01

192

Effect of sulfuric acid in wood plastic composite  

NASA Astrophysics Data System (ADS)

Wood plastic composite was prepared with simul and MMA in the presence of methanol used as swelling agent at different proportions. Sulfuric acid was incorporated into the impregnating solution to investigate its effect on the polymer loading and tensile strength of the composite. 1% Acid solution induces the highest polymer loading. Effect of additives like NVP, TPGDA and TMPTA was also investigated. Corrosion or leaching effect of the acid on the wood samples was studied. Uptake of the impregnating solution by the samples over a period of time was determined.

Husain, M. M.; Khan, Mubarak A.; Ali, K. M. Idriss; Mustafa, A. I.

1996-01-01

193

Analysis of sulfuriodine thermochemical cycle for solar hydrogen production. Part I: decomposition of sulfuric acid  

Microsoft Academic Search

The sulfuriodine (SI) thermochemical water splitting cycle is one of the most studied cycles for hydrogen (H2) production. SI cycle consists of four sections: (I) acid production and separation and oxygen purification, (II) sulfuric acid concentration and decomposition, (III) hydroiodic acid (HI) concentration, and (IV) HI decomposition and H2 purification. Section II of the cycle is an endothermic reaction driven

Cunping Huang; Ali T-Raissi

2005-01-01

194

Catalytic decomposition of spent sulfuric acid in an airfluidized bed  

SciTech Connect

This paper presents results of a study of the catalytic decomposition of spent sulfuric acid, containing benzenesulfonic acid (BSA) on high-temperature nontoxic contact masses, synthesized by the authors, based on iron, copper, and chromium oxides. A scheme of the experimental apparatus is shown illustrating the AFB reactor, thermocouples, potentiometer, filter, etc. In carrying out the experiments on decomposition of SSA, the degree of oxidation of the organic impurities was 100% at 973-1073 K. The flow rate of air in the air-fluidized bed was equal to 0.16-0.22 m/sec in the case of the chromium catalyst, and 0.18-0.24 m/sec in the case of the copper-iron catalyst on the oxygen flame smelting dust. The specific loads of spent sulfuric acid varied from 144.6 to 293.8 kg/(hham/sup 3/). In principle, a possibility was shown of using chromium and iron-copper catalysts in a process of the rgeneration of spent sulfuric acid containing BSA.

Shenfel'd, B.E.; Dobkina, E.I.; Khludenev, A.G.; Solov'eva, E.L.

1985-12-01

195

Regeneration and Recycling of Waste Chromic Acid-Sulfuric Acid Etchants.  

National Technical Information Service (NTIS)

Etchants containing hexavalent chromium and sulfuric acid are used in a variety of surface-finishing operations. When the resultant spent solutions are discarded, substantial quantities of chromium are lost and pollution problems are created. To minimize ...

D. M. Soboroff J. D. Troyer A. A. Cochran

1979-01-01

196

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

PubMed

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 water vapor at ambient conditions limits that process. PMID:22946751

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

2012-10-01

197

Uptake and Dissolution of Gaseous Ethanol in Sulfuric Acid  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

198

Thermal regeneration of sulfuric acid hydrates after irradiation  

NASA Astrophysics Data System (ADS)

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, H2SO44H2O and H2SO4H2O. 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.

Loeffler, Mark J.; Hudson, Reggie L.

2012-06-01

199

Thermal Regeneration of Sulfuric Acid Hydrates after Irradiation  

NASA Technical Reports Server (NTRS)

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.

Loeffler, Mark J.; Hudson, Reggie L.

2012-01-01

200

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

SciTech Connect

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2001 through March 31, 2002. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub X} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, American Electric Power (AEP) and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. This is the fifth reporting period for the subject Cooperative Agreement. During the previous (fourth) period, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Plant. Those tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Plant) and a byproduct magnesium hydroxide slurry (at both Gavin and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70-75% overall sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub X} control than at removing SO{sub 3} formed in the furnace. The SO{sub 3} removal results were presented in the previous semi-annual technical progress report (April 1, 2001 through September 30, 2001). During the current reporting period, additional balance of plant impact information was determined for one of the two tests. These additional balance-of-plant results are presented and discussed in this report. There was no other technical progress to report, because all planned testing as part of this project has been completed.

Gary M. Blythe

2002-04-29

201

Engineering design of a thermochemical water-splitting cycle. Final report. [Sulfuric acid--sulfur oxide--sulfide cycle  

Microsoft Academic Search

In consultation with Los Alamos Scientific Laboratory, the LASL baseline sulfuric acid-sulfur-oxide-sulfide cycle for thermochemical hydrogen production was selected for preliminary engineering design. Using LASL data, or values estimated in collaboration with LASL where data were incomplete, process conditions for all primary reactions were established. Conceptual solutions for separation and recycle processes were developed and combined with the primary reactions

J. De Graaf; L. Halvers; J. Porter; J. Russell

1976-01-01

202

INCREASED INFECTIVITY WITH EXPOSURE TO OZONE AND SULFURIC ACID  

EPA Science Inventory

The effects of the combined action of ozone (O3) and sulfuric acid (H2SO4) aerosol on host susceptibility to an aerosol of viable microorganisms were studied. Exposure to O3 (0.196 mg/cu m) was for 3 h, while exposure to H2SO4 (0.9 mg/cu m) lasted 2 h. Neither pollutant alone cau...

203

Quantum mechanical study of sulfuric acid hydration: atmospheric implications.  

PubMed

The role of the binary nucleation of sulfuric acid in aerosol formation and its implications for global warming is one of the fundamental unsettled questions in atmospheric chemistry. We have investigated the thermodynamics of sulfuric acid hydration using ab initio quantum mechanical methods. For H(2)SO(4)(H(2)O)(n) where n = 1-6, we used a scheme combining molecular dynamics configurational sampling with high-level ab initio calculations to locate the global and many low lying local minima for each cluster size. For each isomer, we extrapolated the Mller-Plesset perturbation theory (MP2) energies to their complete basis set (CBS) limit and added finite temperature corrections within the rigid-rotor-harmonic-oscillator (RRHO) model using scaled harmonic vibrational frequencies. We found that ionic pair (HSO(4)(-)H(3)O(+))(H(2)O)(n-1) clusters are competitive with the neutral (H(2)SO(4))(H(2)O)(n) clusters for n ? 3 and are more stable than neutral clusters for n ? 4 depending on the temperature. The Boltzmann averaged Gibbs free energies for the formation of H(2)SO(4)(H(2)O)(n) clusters are favorable in colder regions of the troposphere (T = 216.65-273.15 K) for n = 1-6, but the formation of clusters with n ? 5 is not favorable at higher (T > 273.15 K) temperatures. Our results suggest the critical cluster of a binary H(2)SO(4)-H(2)O system must contain more than one H(2)SO(4) and are in concert with recent findings (1) that the role of binary nucleation is small at ambient conditions, but significant at colder regions of the troposphere. Overall, the results support the idea that binary nucleation of sulfuric acid and water cannot account for nucleation of sulfuric acid in the lower troposphere. PMID:22296037

Temelso, Berhane; Morrell, Thomas E; Shields, Robert M; Allodi, Marco A; Wood, Elena K; Kirschner, Karl N; Castonguay, Thomas C; Archer, Kaye A; Shields, George C

2012-03-01

204

Binary nucleation of sulfuric acid-water: Monte Carlo simulation  

Microsoft Academic Search

We have developed a classical mechanical model for the H2SO4\\/H2O binary system. Monte Carlo simulation was performed in a mixed ensemble, in which the number of sulfuric acid molecules is fixed while that of water molecules is allowed to fluctuate. Simulation in this ensemble is computationally efficient compared to conventional canonical simulation, both in sampling very different configurations of clusters

I. Kusaka; Z.-G. Wang; J. H. Seinfeld

1998-01-01

205

COS in the stratosphere. [sulfuric acid aerosol precursor  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

206

Phenol-Sulfuric Acid Method for Total Carbohydrates  

NASA Astrophysics Data System (ADS)

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.

Nielsen, S. Suzanne

207

Phenol-Sulfuric Acid Method for Total Carbohydrates  

Microsoft Academic Search

\\u000a The phenol-sulfuric acid method is a simple and rapid colorimetric method to determine total carbohydrates in a sample. The\\u000a method detects virtually all classes of carbohydrates, including mono-, di-, oligo-, and polysaccharides. Although the method\\u000a detects almost all carbohydrates, the absorptivity of the different carbohydrates varies. Thus, unless a sample is known to\\u000a contain only one carbohydrate, the results must

S. Suzanne Nielsen

2010-01-01

208

The Double Contact Process For Sulfuric Acid Production  

Microsoft Academic Search

In the usual contact plants 97-98% of the SO2 is oxidized to SO3 while the remaining 2-3% nonoxidized S02 are emitted. The stack gas generally contains 0.2-0.3% by volume SO2.Through changing to the Bayer Double Contact process, the conversion can be raised to 99.5% or higher. The sulfuric acid can be produced at the same cost as with the single

W. Moeller; K. Winkler

1968-01-01

209

Sulfur  

Microsoft Academic Search

Sulfur, an element in wide industrial use, currently is mined or recovered in the U.S. from elemental sulfur deposits associated with evaporites, from sulfur-bearing petroleum and natural gas, and from sulfide ores. The element also occurs as a constituent in bedded gypsum and anhydrite, coal, tar sands, and oil shale, as well as in volcanic deposits, none of which is

Bodenlos

1973-01-01

210

Sulfuric acid intercalated graphite oxide for graphene preparation.  

PubMed

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 100C in ambient atmosphere, noting that SIGO is easily available as the immediate oxidation descendent of graphite in sulfuric acid. The oxygenic and hydric groups in SIGO are mainly removed through dehydration as catalyzed by the intercalated sulfuric acid (ISA). The resultant consists of mostly single layer graphene sheets with a mean diameter of 1.07??m after dispersion in DMF. This SIGO process is reductant free, easy operation, low-energy, environmental friendly and generates graphene with low oxygen content, less defect and high conductivity. The provided synthesis route from graphite to graphene via SIGO is compact and readily scalable. PMID:24310650

Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

2013-01-01

211

Adsorption of ammonia by sulfuric acid treated zirconium hydroxide.  

PubMed

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. PMID:22686609

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

2012-07-17

212

Sulfuric Acid Intercalated Graphite Oxide for Graphene Preparation  

NASA Astrophysics Data System (ADS)

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 100C in ambient atmosphere, noting that SIGO is easily available as the immediate oxidation descendent of graphite in sulfuric acid. The oxygenic and hydric groups in SIGO are mainly removed through dehydration as catalyzed by the intercalated sulfuric acid (ISA). The resultant consists of mostly single layer graphene sheets with a mean diameter of 1.07 ?m after dispersion in DMF. This SIGO process is reductant free, easy operation, low-energy, environmental friendly and generates graphene with low oxygen content, less defect and high conductivity. The provided synthesis route from graphite to graphene via SIGO is compact and readily scalable.

Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

2013-12-01

213

Configuring the thermochemical hydrogen sulfuric acid process step for the Tandem Mirror reactor  

Microsoft Academic Search

The sulfuric acid step was identified as the critical part of the thermochemical cycle in dictating the thermal demands and temperature requirements of the heat source. The general atomic sulfur-iodine cycle was coupled to a tandem mirror. The sulfuric acid decomposition process step was focused on specifically since this step can use the high efficiency electrical power of the direct

T. R. Galloway

1981-01-01

214

Further studies on the mechanism of phenol-sulfuric acid reaction with furaldehyde derivatives.  

PubMed

Even though the chromogens formed from mannose and galactose showed comparable absorbances at 480 nm in the conventional (developer present during heat of dilution) and modified (developer reacted at room temperature after cooling; epsilon mannose = 13,700, galactose = 14,000) phenol-sulfuric acid reactions, shoulders in the region 420-430 nm were prominent in the former method. Fucose was 10 times less reactive in the modified method (epsilon = 800) than in the conventional method. 2-Formyl-5-furan sulfonic acid reacted equally efficiently in the two methods (epsilon = 40,800). 5-Methyl-2-furaldehyde, unlike the sulfonate derivative or 5-hydroxymethyl-2-furaldehyde, required heat for condensation with phenol. 2-Furaldehyde dimethylhydrazone reacted 25 times better to form a chromogen (epsilon = 40,500) in the modified phenol-sulfuric acid method. The possible roles of intermediates between hexoses and furaldehydes in forming chromogens and the effect of substitution at the 2- and 5-positions of furaldehyde on the rates of condensation with phenol for the observed differences between the conventional and the modified methods are discussed. PMID:2281859

Rao, P; Pattabiraman, T N

1990-09-01

215

Modeling of Sulfuric Acid Condensation on Heat Exchanger Cooling Fins  

NASA Astrophysics Data System (ADS)

Sulfuric acid corrosion on metallic heat exchanger cooling fins can cause serious blockage problem and stop the normal operation of heat exchangers. Corrosion rates are strongly dependent on surface film pH value. Therefore, a multi-physics computational framework was developed to predict the liquid film formed on solid surface and the pH distribution. Such a model can be used for better understanding of acid condensation from multi-species system. In this work, first, from S to H2SO4, formation of sulfuric acid in gas phase during combustion and cooling process was investigated with detailed chemistry mechanisms. The amount of SO2 and SO3 that plays important role in acid condensation process was calculated. Then, multi-component condensation process was modeled to produce a liquid film of acid and water solution condensed on solid surface that has low temperature. pH value was obtained based on the concentration of the acid. The above work provides critical information for corrosion analysis for heat exchangers.

Li, Xiaobai; Cook, David

2011-11-01

216

Coulometric determination of berkelium in sulfuric acid and nitric acid solutions  

SciTech Connect

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.

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

1987-03-01

217

Effects of sulfur dioxide on lichen lipids and fatty acids.  

PubMed

Lipids and fatty acids were studied in some lichen species after exposure to 1 ppm of aqueous sulfur dioxide. The changes in lipid composition are specific to the lichen species tested. The exposure of lichens to SO2 resulted in a slight reduction of the total phospholipid content. The amount of betaine lipid diacylglyceryltrimethylhomoserine was increased in Stereocaulon paschale, but the level of this lipid was not changed in Peltigera aphthosa. An increase in fatty acid unsaturation in lichens in response to the effect of SO2 probably has adaptive significance. PMID:9986914

Bychek-Guschina, I A; Kotlova, E R; Heipieper, H

1999-01-01

218

Sonoluminescence radiation from different concentrations of sulfuric acid.  

PubMed

Sonoluminescence (SL) radiation from an argon bubble in water and in different concentrations of sulfuric acid has numerically been studied to quantify the effects of vapor pressure and viscosity of the liquid on cavitation luminescence in a liquid with controllable vapor pressure and viscosity. For the solutions containing the noble gas with low partial pressure (about 4 Torr), it is shown that there exists an optimum acid solution in which both the temperature and the intensity of SL radiation become maximum. The calculations show that the maximum SL radiation is achieved from the solution of around 65% (wt.) H2SO4, which is in agreement with available experimental results. PMID:19905454

Moshaii, A; Imani, Kh; Silatani, M

2009-10-01

219

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

PubMed

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 135C) and three durations (15, 30, and 45min) followed by detoxification with activated carbon. Of all the combinations, only the treatments obtained at 135C, 2.0% H2SO4, and 45min and the one at 135C, 1.25% H2SO4, and 45min showed inhibition in the growth of the tested microorganisms. Spiked YM broths showed inhibition for the highest levels of inhibitors, either applied individually or in combination. PMID:24502218

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

2014-01-01

220

Sulfuric Acid and Soot Particle Formation in Aircraft Exhaust  

NASA Technical Reports Server (NTRS)

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%.

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

221

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

SciTech Connect

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 (slurry binder) and calcinated. Final polishing of the flange faces established in the entrance nozzles was also satisfactory. Many parts were joinable using new technology (new binder). For this reason, new technology is applicable to manufacture of not only a sulfuric acid decomposer but the instruments in the IS process, or other chemical processes. (authors)

Hiroshi Fukui; Isao Minatsuki [Mitsubishi Heavy Industries, LTD. (Japan); Kazuo Ishino [Pacific Rundum Co., Ltd. (Japan)

2006-07-01

222

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

SciTech Connect

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2003 through September, 2003. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub x} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, American Electric Power (AEP) and the Dravo Lime Company are project co-funders. URS Group is the prime contractor. This is the eighth reporting period for the subject Cooperative Agreement. During previous reporting periods, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Plant. Those tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Plant), and a byproduct magnesium hydroxide slurry (both Gavin Plant and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70-75% overall sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub x} control than at removing SO{sub 3} formed in the furnace. The SO{sub 3} removal results were presented in the semi-annual Technical Progress Report for the time period April 1, 2001 through September 30, 2001. Additional balance of plant impact information for the two tests was reported in the Technical Progress Report for the time period October 1, 2001 through March 30, 2002. Additional information became available about the effects of byproduct magnesium hydroxide injection on SCR catalyst coupons during the long-term test at BMP, and those results were reported in the report for the time period April 1, 2002 through September 30, 2002. During the current period, process economic estimates were developed, comparing the costs of the furnace magnesium hydroxide slurry injection process tested as part of this project to a number of other candidate SO{sub 3}/sulfuric acid control technologies for coal-fired power plants. The results of this economic evaluation are included in this progress report.

Gary M. Blythe

2003-10-01

223

Dilute-Acid Hydrolysis of Cellulosic Materials III: Kinetics of a Lignocellulose Residue.  

National Technical Information Service (NTIS)

Kinetics of dilute-acid hydrolysis of lignocellulose residue from a furfural process is investigated experimentally. The rate constants are determined by a simplified method. By comparing with the kinetics of waste paper hydrolysis in similar conditions t...

V. J. Pohjola M. Pulkkinen P. Perttila

1977-01-01

224

High Temperature Dilute Acid Hydrolysis of Waste Cellulose: Batch and Continuous Processes.  

National Technical Information Service (NTIS)

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

W. Brenner B. Rugg

1985-01-01

225

Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design  

NASA Astrophysics Data System (ADS)

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 825C to 926C 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 350C. 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 600C to 926C. Other materials, including natural diamond, synthetic diamond treated with titanium, silicon carbide, quartz, aluminum nitride, and Inconel were also tested in the simulator to determine corrosion resistances. The study concluded that boron treated diamonds were not suitable for use in decomposer process equipment. Unacceptable corrosion rates were observed at 600C and increased linearly with temperature up to 700C. The boron treated diamonds completely disassociated at temperatures above 700C. The researcher postulated that the high corrosion rates resulted from diamond carbon having a higher preference for oxygen free radicals formed during the decomposition process. Oxygen free radical concentration also increased as a function of increasing temperature. The study also concluded that natural diamond and synthetic titanium treated diamond were unsuitable for use in decomposer process equipment. The corrosion results were similar to that of the boron treated diamonds. Silicon carbide may have potential for used in decomposer process equipment. No appreciable silicon carbide corrosion was observed and more study is warranted. Small amounts of quartz and aluminum nitride corrosion was observed. Inconel corrosion rates were very high at all temperatures tested.

Peck, Michael S.

226

Growth peculiarities of aluminum anodic oxide at high voltages in diluted phosphoric acid  

Microsoft Academic Search

The growth of porous aluminium anodic oxide films on 99.5%, 99.99% and 99.999% purity Al metal in stirred dilute phosphoric acid solutions (0.0050.4moll?1) at 220C temperature and relative high anodizing voltages was studied. A kinetic model is proposed for solutions of concentration up to 0.1moll?1. The size of cells in the films formed in dilute phosphoric acid solution varies linearly

A. Jagminas; I Mikulskas; R Tomai?nas

2001-01-01

227

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

Microsoft Academic Search

The uptake of Hci molecules by acqueous sulfuric acid droplets was measured at 283 K as a function of acid mole fraction. In the apparatus a controllable stream of monodispersed droplets is produced by a vibrating orifice jet. The droplets enter a flow system containing HCl(g). The droplets are switched on and off while the density of the species is

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

1990-01-01

228

Xanthan Sulfuric Acid: An Efficient and Recyclable Solid Acid Catalyst for Pechmann Condensation  

Microsoft Academic Search

In this report, substituted coumarins are formed via Pechmann condensation using various substituted phenols and ethyl acetoacetates in the presence of xanthan sulfuric acid as a solid acid catalyst under solvent-free conditions. This method is very simple, cost-effective, and has shorter reaction times, and the catalyst could be reused.

B. Suresh Kuarm; J. Venu Madhav; B. Rajitha

2012-01-01

229

Xanthan Sulfuric Acid: An Efficient and Recyclable Solid Acid Catalyst for Pechmann Condensation  

Microsoft Academic Search

In this paper, substituted coumarins are reported via Pechmann condensation by using various substituted phenols and ethyl acetoacetates in presence of Xanthan sulfuric acid as a solid acid catalyst under solvent-free conditions. This method is very simple, cost effective, shorter reaction times and the catalyst could be reused.

B. Suresh Kuarm; J. Venu Madhav; B. Rajitha

2011-01-01

230

SULFURIC ACID REMOVAL PROCESS EVALUATION: LONG-TERM RESULTS  

SciTech Connect

The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The project is being co-funded by the U.S. DOE National Energy Technology Laboratory, under Cooperative Agreement DE-FC26-99FT40718, along with EPRI, the American Electric Power Company (AEP), FirstEnergy Corp., the Tennessee Valley Authority, and Dravo Lime, Inc. Sulfuric acid controls are becoming of increasing interest to power generators with coal-fired units for a number of reasons. Sulfuric acid is a Toxic Release Inventory species and can cause a variety of plant operation problems such as air heater plugging and fouling, back-end corrosion, and plume opacity. These issues will likely be exacerbated with the retrofit of selective catalytic reduction (SCR) for NO{sub x} control on many coal-fired plants, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project previously tested the effectiveness of furnace injection of four different calcium-and/or magnesium-based alkaline sorbents on full-scale utility boilers. These reagents were tested during four one- to two-week tests conducted on two FirstEnergy Bruce Mansfield Plant (BMP) units. One of the sorbents tested was a magnesium hydroxide byproduct slurry produced from a modified Thiosorbic{reg_sign} Lime wet flue gas desulfurization system. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercial magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners, while the other three reagents were injected as slurries through air-atomizing nozzles inserted through the front wall of the upper furnace, either across from the nose of the furnace or across from the pendant superheater tubes. After completing the four one- to two-week tests, the most promising sorbents were selected for longer-term (approximately 25-day) full-scale tests on two different units. The longer-term tests were conducted to confirm the effectiveness of the sorbents tested over extended operation on two different boilers, and to determine balance-of-plant impacts. The first long-term test was conducted on FirstEnergy's BMP, Unit 3, and the second test was conducted on AEP's Gavin Plant, Unit 1. The Gavin Plant testing provided an opportunity to evaluate the effects of sorbent injected into the furnace on SO{sub 3} formed across an operating SCR reactor. This report presents the results from those long-term tests. The tests determined the effectiveness of injecting commercially available magnesium hydroxide slurry (Gavin Plant) and byproduct magnesium hydroxide slurry (both Gavin Plant and BMP) for sulfuric acid control. The results show that injecting either slurry could achieve up to 70 to 75% overall sulfuric acid removal. At BMP, this overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NOX control than at removing SO{sub 3} formed in the furnace. The long-term tests also determined balance-of-plant impacts from slurry injection during the two tests. These include impacts on boiler back-end temperatures and pressure drops, SCR catalyst properties, ESP performance, removal of other flue gas species, and flue gas opacity. For the most part the balance-of-plant impacts were neutral to positive, although adverse effects on ESP performance became an issue during the BMP test.

Gary M. Blythe; Richard McMillan

2002-07-03

231

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

PubMed

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 0.2g ethanol from 1g PS sorghum). A detail mass balance was also provided. PMID:21153666

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

2011-05-01

232

Theoretical study of formic acid-sulfur dioxide dimers.  

PubMed

We report the first theoretical study of noncovalent and covalent interactions in formic acid (FA)-SO(2) complexes. Using ab initio and DFT model chemistries, five stable noncovalent complexes were identified, as well as a covalent adduct, formic sulfurous anhydride HOSO(2)CHO. syn-FA is predicted to form two nonplanar bidentate complexes with SO(2): the more stable one contains a normal hydrogen bond donated by OH, and the less stable one contains a blue-shifted hydrogen bond donated by CH. Both are stabilized by charge transfer from FA to SO(2). anti-FA forms three planar complexes of nearly equal energy containing OH-to-SO(2) hydrogen bonds. Formic sulfurous anhydride forms via an endothermic concerted cycloaddition. Natural bond orbital analysis showed that the bidentate SO(2)-FA complexes are stabilized by n ? ?* donation from FA to SO(2), and back-donation from SO(2) n and ?* orbitals into FA ?(OH)* or ?(CH)* orbitals. The bidentate formic acid-SO(2) complex that contains an O-HO hydrogen bond is more stable than the similar nitric acid-SO(2) complex. The latter contains a stronger hydrogen bond but shows no O?S charge transfer interaction. PMID:21117658

Keller, John W; Harrod, Bronwyn L; Chowdhury, Sifat A

2010-12-23

233

Sulfuric acid cloud interpretation of the infrared spectrum of Venus  

NASA Technical Reports Server (NTRS)

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.

Martonchik, J. V.

1974-01-01

234

A rotamer energy level study of sulfuric acid.  

PubMed

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. PMID:24116623

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

2013-10-14

235

Chemical coal beneficiation with aqueous hydrogen peroxide\\/sulfuric acid solutions  

Microsoft Academic Search

The removal of sulfur and ash from coal treated with aqueous hydrogen peroxide\\/sulfuric acid solutions at ambient temperature was studied under a variety of experimental conditions. Almost complete elimination of the sulfate and the pyritic sulfur was observed in most cases, as well as substantial reduction in the ash content. The rest of the organic coal matrix was not affected

N. P. Vasilakos; C. S. Clinton

1983-01-01

236

Chemical coal beneficiation with aqueous hydrogen peroxide\\/sulfuric acid solution  

Microsoft Academic Search

The removal of sulfur and ash from coal treated with aqueous hydrogen peroxide\\/sulfuric acid solutions at ambient temperature was studied under a variety of experimental conditions. Almost complete elimination of the sulfate and the pyritic sulfur was observed in most cases, along with substantial reduction in ash content. The remainder of the coal matrix was not affected significantly, thus indicating

N. P. Vasilakos; C. S. Clinton

1983-01-01

237

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

Microsoft Academic Search

Few measurements of H2SO4 vapor pressure have been made for sulfuric acid in the temperature and concentration ranges of atmospheric interest because of the very low pressures involved (below 10-4Pa, or 10-6torr); no such measurements appear to have been made for sulfuric acid solutions neutralized with ammonia. This work presents measurements of H2SO4 vapor pressure for aqueous sulfuric acid solutions

James J. Marti; Anne Jefferson; Xiao Ping Cai; Chad Richert; Peter H. McMurry; Fred Eisele

1997-01-01

238

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

SciTech Connect

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2002 through March 31, 2003. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub x} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, American Electric Power (AEP) and the Dravo Lime Company are project co-funders. URS Group is the prime contractor. This is the seventh reporting period for the subject Cooperative Agreement. During previous reporting periods, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Plant. Those tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Plant), and a byproduct magnesium hydroxide slurry (both Gavin Plant and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70-75% overall sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Plant, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub x} control than at removing SO{sub 3} formed in the furnace. The SO3 removal results were presented in the semi-annual Technical Progress Report for the time period April 1, 2001 through September 30, 2001. Additional balance of plant impact information for the two tests was reported in the Technical Progress Report for the time period October 1, 2001 through March 30, 2002. Additional information became available about the effects of byproduct magnesium hydroxide injection on SCR catalyst coupons during the long-term test at BMP, and those results were reported in the previous report (April 1, 2002 through September 30, 2002). During the current period, there was no technical progress to report, because all planned testing as part of this project has been completed. The project period of performance was extended to allow the conduct of testing of another SO{sub 3} control technology, the sodium bisulfite injection process. However, these additional tests have not yet been conducted.

Gary M. Blythe

2003-06-01

239

LASL thermochemical hydrogen program status on October 31, 1977. [Cycles using sulfuric acid as an intermdiate  

Microsoft Academic Search

The LASL Hydrogen Program is continuing its investigation of practical schemes to decompose water thermochemically for hydrogen production. Efforts were and are being devoted to process improvements in cycles that use sulfuric acid as an intermediate. Sulfuric acid-hydrogen bromide cycles are being studied as a means of overcoming the heat penalty in drying acid solutions. An alternate approach involves the

K. E. Cox; M. G. Bowman

1977-01-01

240

Physicochemical study of poly(ether ether ketone) electrolyte membranes sulfonated with mixtures of fuming sulfuric acid and sulfuric acid for direct methanol fuel cell application  

Microsoft Academic Search

Sulfonated poly(ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) have been prepared as a potential membrane material for proton exchange membrane by sulfonation process using mixtures of (1530% concentration) fuming sulfuric acid and (9598%) concentrated sulfuric acid as the sulfonating agent. The sulfonation process was conducted at room temperature by varying the acid ratio and reaction time.

J. Jaafar; A. F. Ismail; A. Mustafa

2007-01-01

241

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

NASA Astrophysics Data System (ADS)

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

Henschel, Henning; Ortega, Ismael K.; Kupiainen, Oona; Olenius, Tinja; Kurtn, Theo; Vehkamki, Hanna

2013-05-01

242

Resolving the shape of a sonoluminescence pulse in sulfuric acid by the use of streak camera.  

PubMed

A streak camera is used to measure the shape of sonoluminescence pulses from a cavitation bubble levitated stably in a sulfuric acid solution. The shape and response to an acoustic pressure field of the sonoluminescence pulse in 85% by weight sulfuric acid are qualitatively similar to those in water. However, the pulse width in sulfuric acid is wider than that in water by over one order of magnitude. The width of the sonoluminescence pulse is strongly dependent on the concentration of the sulfuric acid solution, while the skewed distribution of the shape remains unchanged. PMID:19507941

Huang, Wei; Chen, Weizhong; Cui, Weicheng

2009-06-01

243

Corrosion of stainless steels in acid solutions with organic sulfur-containing compounds  

Microsoft Academic Search

The influence of the organic sulfur-containing compounds on the corrosion of ferrite and austenitic stainless steels in sulfuric acid was studied. The results showed that the anodic dissolution and self-corrosion of stainless steels were remarkably accelerated in solutions with a low amount of the organic sulfur-containing compounds (0.02 mmol\\/dm3). With an increase of the organic sulfur-containing compound concentration, more and

X. L Cheng; H. Y Ma; S. H Chen; R Yu; X Chen; Z. M Yao

1998-01-01

244

Gaseous sulfuric acid and sulfur dioxide measurements in the Arctic troposphere and lower stratosphere - Implications for hydroxyl radical abundances  

Microsoft Academic Search

Measurements of gaseous sulfuric acid and sulfur dioxide were made in the winter Arctic troposphere and lower stratosphere using aircraft-borne mass spectrometers. The measurements, covering altitudes between 3.5 and 11.4 km, took place on 14 and 18 February, 1987 in northern Scandinavia. The abundance of H2SO4 was around 0.01 to 0.06 pptv (parts per trillion by volume), and the measured

O. Moehler; F. Arnold

1992-01-01

245

Laboratory measurements of heterogeneous reactions on sulfuric acid surfaces  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

246

Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks  

NASA Technical Reports Server (NTRS)

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).

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

1979-01-01

247

Involvement of Intermediate Sulfur Species in Biological Reduction of Elemental Sulfur under Acidic, Hydrothermal Conditions  

PubMed Central

The thermoacidophile and obligate elemental sulfur (S80)-reducing anaerobe Acidilobus sulfurireducens 18D70 does not associate with bulk solid-phase sulfur during S80-dependent batch culture growth. Cyclic voltammetry indicated the production of hydrogen sulfide (H2S) as well as polysulfides after 1 day of batch growth of the organism at pH 3.0 and 81C. The production of polysulfide is likely due to the abiotic reaction between S80 and the biologically produced H2S, as evinced by a rapid cessation of polysulfide formation when the growth temperature was decreased, inhibiting the biological production of sulfide. After an additional 5 days of growth, nanoparticulate S80 was detected in the cultivation medium, a result of the hydrolysis of polysulfides in acidic medium. To examine whether soluble polysulfides and/or nanoparticulate S80 can serve as terminal electron acceptors (TEA) supporting the growth of A. sulfurireducens, total sulfide concentration and cell density were monitored in batch cultures with S80 provided as a solid phase in the medium or with S80 sequestered in dialysis tubing. The rates of sulfide production in 7-day-old cultures with S80 sequestered in dialysis tubing with pore sizes of 12 to 14 kDa and 6 to 8 kDa were 55% and 22%, respectively, of that of cultures with S80 provided as a solid phase in the medium. These results indicate that the TEA existed in a range of particle sizes that affected its ability to diffuse through dialysis tubing of different pore sizes. Dynamic light scattering revealed that S80 particles generated through polysulfide rapidly grew in size, a rate which was influenced by the pH of the medium and the presence of organic carbon. Thus, S80 particles formed through abiological hydrolysis of polysulfide under acidic conditions appeared to serve as a growth-promoting TEA for A. sulfurireducens.

Druschel, Gregory K.

2013-01-01

248

Sulfuric Acid Monohydrate: Formation and Heterogeneous Chemistry in the Stratosphere  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

249

Ambient temperature effect on single-bubble sonoluminescence in different concentrations of sulfuric acid solutions  

NASA Astrophysics Data System (ADS)

The effect of ambient temperature on the parameters of the single-bubble sonoluminescence in sulfuric acid (SA) diluted in water is studied. Using a hydrochemical model, three dominant instabilities of shape, Bjerknes, and diffusion are considered. The phase diagrams of the bubble in the (R0 - Pa) space are presented, and the parametric dependence of the light intensity is discussed. In contrast to water, the calculated thermal-bremsstrahlung mechanism of light emission at the fixed degassing condition of high SA concentrations shows that, with increasing the temperature of aqueous SA solutions, the light intensity increases. However, at diluted SA solutions similar to water, the light intensity decreases with increasing the ambient temperature. For 50 wt % SA, it was observed that the emitted light was almost temperature independent. Furthermore, it is found that, at the fixed temperatures of 20 C, 10 C, and 0 C, the aqueous solutions of 65 wt %, 50 wt %, and 45 wt % SA, respectively, have the maximum light emission.

Imani, Kh.; Bemani, F.; Silatani, M.; Sadighi-Bonabi, R.

2012-01-01

250

Ambient temperature effect on single-bubble sonoluminescence in different concentrations of sulfuric acid solutions.  

PubMed

The effect of ambient temperature on the parameters of the single-bubble sonoluminescence in sulfuric acid (SA) diluted in water is studied. Using a hydrochemical model, three dominant instabilities of shape, Bjerknes, and diffusion are considered. The phase diagrams of the bubble in the (R0 - Pa) space are presented, and the parametric dependence of the light intensity is discussed. In contrast to water, the calculated thermal-bremsstrahlung mechanism of light emission at the fixed degassing condition of high SA concentrations shows that, with increasing the temperature of aqueous SA solutions, the light intensity increases. However, at diluted SA solutions similar to water, the light intensity decreases with increasing the ambient temperature. For 50 wt % SA, it was observed that the emitted light was almost temperature independent. Furthermore, it is found that, at the fixed temperatures of 20?C, 10?C, and 0?C, the aqueous solutions of 65 wt %, 50 wt %, and 45 wt % SA, respectively, have the maximum light emission. PMID:22400679

Imani, Kh; Bemani, F; Silatani, M; Sadighi-Bonabi, R

2012-01-01

251

Catalytic decomposition of sulfuric acid on mixed Cr\\/Fe oxide samples and its application in sulfuriodine cycle for hydrogen production  

Microsoft Academic Search

The present paper deals with the catalytic decomposition of sulfuric acid reaction which is common to several sulfur based thermochemical water splitting cycles including the sulfuriodine thermochemical cycle. The activity and stability of Cr substituted Fe oxide catalysts were studied for the sulfuric acid decomposition reaction. The samples Fe2(1-x)Cr2xO3 were synthesized using ceramic route and characterized by XRD, N2-BET and

A. M. Banerjee; M. R. Pai; K. Bhattacharya; A. K. Tripathi; V. S. Kamble; S. R. Bharadwaj; S. K. Kulshreshtha

2008-01-01

252

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

253

Changes in pulmonary lavage fluid of guinea pigs exposed to ultrafine zinc oxide with adsorbed sulfuric acid  

Microsoft Academic Search

Ultrafine metal oxide particles (diameters less than 0.1 ?m) and sulfur dioxide are important products of coal combustion. Interaction of these products in the effluent stream results in formation of ultrafine particles with adsorbed sulfur compounds, including sulfuric acid. The toxicity of ultrafine zinc oxide particles with adsorbed sulfuric acid was evaluated by comparing pulmonary lavage fluid from guinea pigs

Michael W. Conner; William H. Flood; Adrianne E. Rogers; Mary O. Amdur

1989-01-01

254

Continuous fermentation of undetoxified dilute acid lignocellulose hydrolysate by Saccharomyces cerevisiae ATCC 96581 using cell recirculation.  

PubMed

Saccharomyces cerevisiae ATCC 96581 was cultivated in a chemostat reactor with undetoxified dilute acid softwood hydrolysate as the only carbon and energy source. The effects of nutrient addition, dilution rate, cell recirculation, and microaerobicity were investigated. Fermentation of unsupplemented dilute acid lignocellulose hydrolysate at D = 0.10 h(-1) in an anaerobic continuous reactor led to washout. Addition of ammonium sulfate or yeast extract was insufficient for obtaining steady state. In contrast, dilute acid lignocellulose hydrolysate supplemented with complete mineral medium, except for the carbon and energy source, was fermentable under anaerobic steady-state conditions at dilution rates up to 0.14 h(-1). Under these conditions, washout occurred at D = 0.15 h(-1). This was preceded by a drop in fermentative capacity and a very high specific ethanol production rate. Growth at all different dilution rates tested resulted in residual sugar in the chemostat. Cell recirculation (90%), achieved by cross-flow filtration, increased the sugar conversion rate from 92% to 99% at D = 0.10 h(-1). Nutrient addition clearly improved the long-term ethanol productivity in the recirculation cultures. Application of microaerobic conditions on the nutrient-supplemented recirculation cultures resulted in a higher production of biomass, a higher cellular protein content, and improved fermentative capacity, which further improves the robustness of fermentation of undetoxified lignocellulose hydrolysate. PMID:16080688

Brandberg, Tomas; Sanandaji, Nima; Gustafsson, Lena; Franzn, Carl Johan

2005-01-01

255

Effect of solution flow rate and direction on copper electrodeposition process from sulfuric acid electrolyte on porous electrode with high electric conductivity  

Microsoft Academic Search

The effect of solution flow direction and rate on the dynamics of copper electrodeposition onto a premetallized coal-graphite\\u000a VINN-250 material from a dilute copper sulfate sulfuric acid solution is experimentally studied in the direct-flow mode. A\\u000a light effect of solution supply on the copper deposit final mass for high and low solution flow rates is found, while the\\u000a effect of

A. Zh. Medvedev; A. F. Zherebilov; A. I. Masliiy; N. P. Poddubnyi

2008-01-01

256

Thermal decomposition of dilute aqueous formic acid solutions.  

National Technical Information Service (NTIS)

Formic acid and formiate are oxidized in aqueous solutions at 260 deg. C and 20 bars O2. The formiate is converted to bicarbonate. The formic acid is both oxidized and decomposed by different routes: HCOOH -> CO + H2O and HCOOH -> CO2 + H2. In particular,...

A. B. Bjerre E. Soerensen

1989-01-01

257

Review and Evaluation of Recent Literature Relevant to Occupational Exposure--Sulfuric Acid.  

National Technical Information Service (NTIS)

New information on the effects of sulfuric-acid is reviewed in an updated supplement to the 1974 NIOSH criteria document accompanying the recommended exposure standard. In 1974, a permissible exposure limit of 1 milligram (mg) sulfuric-acid mist per cubic...

I. F. Sevin L. S. Soucek

1981-01-01

258

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

Microsoft Academic Search

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

K. F. Palmer; Dudley Williams

1975-01-01

259

Molecular sieve control process in sulfuric acid plants. Final report, Oct 1974--Oct 1975  

Microsoft Academic Search

The report gives results of an engineering analysis of the applicability of molecular sieve technology to the control of SO emissions from sulfuric acid plants. After the equivalent of 10 months of operation, one plant using this technology is still controlling SO emissions to well within Federal and State regulations for sulfuric acid plants. It is also meeting the performance

Hissong

1975-01-01

260

COMBINED EFFECT OF OZONE AND SULFURIC ACID ON PULMONARY FUNCTION IN MAN (JOURNAL VERSION)  

EPA Science Inventory

A potential synergistic effect of ozone and sulfuric acid mist (H2SO4) on respiratory function has been postulated for humans exposed to these two pollutants simultaneously. Nine young men were exposed to 0.25 ppm ozone (03), 1200-1600 mcg/cu m sulfuric acid aerosol (H2SO4), and ...

261

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

EPA Science Inventory

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

262

EFFECTS OF ENDOGENOUS AMMONIA ON NEUTRALIZATION OF INHALED SULFURIC ACID AEROSOLS  

EPA Science Inventory

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

263

An improved parameterization for sulfuric acid-water nucleation rates for tropospheric and stratospheric conditions  

Microsoft Academic Search

In this paper we present parameterized equations for calculation of sulfuric acid-water critical nucleus compositions, critical cluster radii and homogeneous nucleation rates for tropospheric and stratospheric conditions. The parameterizations are based on a classical nucleation model. We used an improved model for the hydrate formation relying on ab initio calculations of small sulfuric acid clusters and on experimental data for

H. Vehkamki; M. Kulmala; I. Napari; K. E. J. Lehtinen; C. Timmreck; M. Noppel; A. Laaksonen

2002-01-01

264

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

ERIC Educational Resources Information Center

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)

Myers, R. Thomas

1983-01-01

265

ANALYSIS SYSTEM FOR TOTAL SULFURIC ACID IN AMBIENT AIR. DEVELOPMENT AND PRELIMINARY EVALUATION  

EPA Science Inventory

A total sulfuric acid analysis (TSAA) system was developed and shown to provide quantitative determinations of sulfuric acid in air at concentrations as low as 0.26 micrograms/cu m. Quantitation at lower concentrations appears to be possible. The general approach in the design an...

266

Atmospheric fluidized-bed combustion waste utilization in cement and sulfuric acid: Preliminary feasibility study  

Microsoft Academic Search

An OACD interdisciplinary project team has investigated the preliminary feasibility of using atmospheric fluidized-bed combustion (AFBC) waste in the production of portland cement and sulfuric acid. This investigation found that it is technically and economically feasible to simultaneously produce electricity, portland cement, and sulfuric acid in an environmentally clean, integrated industrial complex. This complex would include a 500-MW AFBC unit

D. G. Salladay; D. E. Nichols; J. T. Berry; D. B. Call; E. A. Harre; Y. K. Kim

1986-01-01

267

Determining insoluble impurities in spent sulfuric acid from the production of synthetic alcohols  

Microsoft Academic Search

Ammonium sulfate is produced from spent sulfuric acid from the production of alcohols. Certain mineral and organic impurities exist in the sulfuric acid that impair the quality of the ammonium sulfate. A detailed method for the chemical analysis for the impurities is presented.

A. V. Antonov; M. K. Kuznetsova

1983-01-01

268

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

EPA Science Inventory

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

269

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

Microsoft Academic Search

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

Georgina C Laredo; Carla R Lpez; Regina E lvarez; Jos L Cano

2004-01-01

270

Metal extraction from spent sulfuric acid catalyst through alkaline and acidic leaching  

Microsoft Academic Search

Spent catalyst from manufacture of sulfuric acid production (main elemental composition: 3.5% V, 0.63% Ni, 7.9% Fe and 9.64% Si) can be used as a secondary source of vanadium and nickel. Extraction of these metals was studied using two different leaching systems (alkaline and acidic). Statistical design of the experiments and ANOVA (analysis of variance) were performed in order to

A. Ognyanova; A. T. Ozturk; I. De Michelis; F. Ferella; G. Taglieri; A. Akcil; F. Vegli

2009-01-01

271

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

ERIC Educational Resources Information Center

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)

Goss, Lisa M.

2003-01-01

272

Uptake of isoprene by thin sulfuric acid films: Acid catalyzed heterogeneous uptake and the formation of monoterpenes and cyclic sesquiterpenes  

Microsoft Academic Search

A high vacuum Knudsen flow reactor was used to determine the 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 (10-6 Torr - 10-4 Torr) studied. However, the uptake coefficient

B. M. Connelly; M. Tolbert

2008-01-01

273

Use of Empty Fruit Bunches from the Oil Palm for bioethanol production: A thorough comparison between dilute acid and dilute alkali pretreatment.  

PubMed

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 (161.5C, 9.44min 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. PMID:24662312

Chiesa, S; Gnansounou, E

2014-05-01

274

Note: electrochemical etching of silver tips in concentrated sulfuric acid.  

PubMed

Sharp metal tips have many uses, including in scanning probe microscopy. Silver is a particularly interesting metal for plasmonic enhancement, e.g., in tip-enhanced Raman spectroscopy, however few methods for the production of silver tips have been explored. A simple and reliable one step dc electrochemical method for the production of sharp silver tips in concentrated H2SO4 is presented. The optimal conditions are 10 V cell voltage and 99% sulfuric acid for tip radii below 100 nm. A LabView program was written to control the cut-off of the circuit to within a millisecond to avoid blunting the tips after drop-off. PMID:23464271

Hodgson, P A; Wang, Y; Mohammad, A Awez; Kruse, P

2013-02-01

275

Periodic behavior in the iron/sulfuric acid system  

SciTech Connect

Potentiostatic current oscillations observed during the anodic dissolution of an iron electrode in a sulfuric acid electrolyte are considered. This behavior has been experimentally characterized with respect to its potential dependence. A new mechanism has been developed that is consistent with observed behaviors and trends. This mechanism combines previously developed ideas concerning periodic behavior and passivation of iron with a new interpretation of precipitated salt-film behavior. The salt film is taken to be nonporous, serving as both a necessary precursor to oxide passivation as well as an effective passivating species itself. The mechanism is well corroborated by results from a mathematical model which also highlights the necessity of salt-film precipitation for the development of periodic behavior. Additionally, the issue of coherence is explicitly considered.

Rush, B.; Newman, J. [Lawrence Berkeley Lab., CA (United States). Energy and Environment Division]|[Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

1995-11-01

276

Coupling interactions between sulfurous acid and the hydroperoxyl radical.  

PubMed

Radical-molecule complexes associated with the hydroperoxyl radical (HOO) play an important role in atmospheric chemistry. Herein, the nature of the coupling interactions between sulfurous acid (H(2)SO(3)) and the HOO radical is systematically investigated at the B3LYP/6-311++G(3df,3pd) level of theory in combination with the atoms in molecules (AIM) theory, the natural bond orbital (NBO) method, and energy decomposition analyses (EDA). Eight stable stationary points possessing double H-bonding features were located on the H(2)SO(3)...HOO potential energy surface. The largest binding energies of -12.27 and -11.72 kcal mol(-1) are observed for the two most stable complexes, where both of them possess strong double intermolecular H-bonds of partially covalence. Moreover, the characteristics of the IR spectra for the two most stable complexes are discussed to provide some help for their possible experimental identification. PMID:20041456

Li, Ping; Ma, Zhi-Ying; Wang, Wei-Hua; Shen, Zhi-Tao; Bi, Si-Wei; Sun, Hai-Tao; Bu, Yu-Xiang

2010-02-22

277

[Leaching kinetics of josephinite tailings with sulfuric acid].  

PubMed

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

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

2013-07-01

278

Decomposition of sulfuric acid using solar thermal energy  

SciTech Connect

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

Not Available

1985-02-01

279

CE IGCC Repowering plant sulfuric acid plant. Topical report, June 1993  

SciTech Connect

A goal of the CE IGCC Repowering project is to demonstrate a hot gas clean-up system (HGCU), for the removal of sulfur from the product gas stream exiting the gasifier island. Combustion Engineering, Inc. (ABB CE) intends to use a HGCU developed by General Electric Environmental Services (GEESI). The original design of this system called for the installation of the HGCU, with a conventional cold gas clean-up system included as a full-load operational back-up. Each of these systems removes sulfur compounds and converts them into an acid off-gas. This report deals with the investigation of equipment to treat this off-gas, recovering these sulfur compounds as elemental sulfur, sulfuric acid or some other form. ABB CE contracted ABB Lummus Crest Inc. (ABB LCI) to perform an engineering evaluation to compare several such process options. This study concluded that the installation of a sulfuric acid plant represented the best option from both a technical and economic point of view. Based on this evaluation, ABB CE specified that a sulfuric acid plant be installed to remove sulfur from off-gas exiling the gas clean-up system. ABB LCI prepared a request for quotation (RFQ) for the construction of a sulfuric acid production plant. Monsanto Enviro-Chem Inc. presented the only proposal, and was eventually selected as the EPC contractor for this system.

Chester, A.M.

1993-12-01

280

Alkylsulfonic acids and some S-containing detergents as sulfur sources for growth of Chlorella fusca  

Microsoft Academic Search

Chlorella fusca can utilize the following substances as sole sulfur sources for growth: C1 to C8 n-alkane-1-sulfonates, linear alkylbenzenes sulfonates (LAS), a-sulfonated fatty acid esters, polyethylene glycol sulfate and alkylsulfates. Good sulfur sources are alkylsulfonic acids, which are comparable to sulfate. Ethanesulfonic acid was used for comparison of the growth on sulfate and on a sulfonic acid, because best growth

Susanne Biedlingmaier; Ahlert Schmidt

1983-01-01

281

Heterogeneous Chemistry of HO2NO2 on Liquid Sulfuric Acid  

NASA Technical Reports Server (NTRS)

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.

Leu, Ming-Taun

1995-01-01

282

Sulfuric acid rain effects on crop yield and foliar injury. Final report  

Microsoft Academic Search

A study was undertaken to determine the relative sensitivity of major U.S. crops to sulfuric acid rain. Plants were grown under controlled environmental conditions and exposed to simulated acid rain of three sulfuric acid concentrations (pH 3.0, 3.5, 4.0) or to a control rain (pH 5.7). Injury to foliage and effects on yield were common responses to acid rain. However,

J. J. Lee; G. E. Neely; S. C. Perrigan

1980-01-01

283

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

PubMed

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

Boyd, Eric S; Druschel, Gregory K

2013-03-01

284

Adsorption of phenol and benzoic acid from dilute aqueous solution onto macroreticular resin  

Microsoft Academic Search

The adsorption of phenol and benzoic acid from dilute aqueous solution onto macroreticular resin was studied by a radiotracer technique for 0.4948-0.0003 mg\\/ml benzoic acid solutions at 25°C and for similar concentrations of phenol at 0°, 25°, and 70°C. Adsorption equilibrium with the Amberlite XAD-8 resin slurry was reached after 44 hr for benzoic acid and after 104 hr for

D. S. Farrier; A. L. Hines; S. W. Wang

1979-01-01

285

Isotope dilution liquid chromatography-tandem mass spectrometry for quantitative amino acid analysis.  

PubMed

The role of amino acid analysis in bioanalysis has changed from a qualitative to a quantitative technique. With the discovery of both electrospray ionization and matrix-assisted laser desorption ionization in the early 1990s, the use of amino acid analysis for qualitative analysis of proteins and peptides has been replaced by mass spectrometry. Accurate measurement of the relative molecular masses of proteins and peptides, peptide mapping, and sequencing by tandem mass spectrometry provide significantly better qualitative information than can be achieved from amino acid analysis. At NIST, amino acid analysis is used to assign concentration values to protein and peptide standard reference materials (SRMs) which, subsequently, will be used in the calibration of a wide variety of protein and peptide assays, such as those used in clinical diagnostics. It is critical that the amino acid analysis method used at NIST for SRM measurement deliver the highest accuracy and precision possible. Therefore, we have developed an amino acid analysis method that uses isotope dilution LC-MS/MS - the analytical technique routinely used at NIST to certify analyte concentrations in SRMs for a wide variety of analytes. Amino acid analysis by isotope dilution LC-MS/MS was first used to measure the concentration of bovine serum albumin in NIST SRM 927d ("bovine serum albumin, 7% solution"). We have recently refined our isotope dilution LC-MS/MS amino acid analysis method to certify the concentration of 17 amino acids in NIST SRM 2389a ("amino acids in 0.1 mol/L hydrochloric acid"). We present here our most recent method for the quantification of amino acids using isotope dilution LC-MS/MS. PMID:22125133

Bunk, David M; Lowenthal, Mark S

2012-01-01

286

THE SOLUTION OF SOIL MINERALS IN DILUTE ACIDS.  

PubMed

Montmorillonite goes readily into solution in slightly acid water. In strong acids only bases, in pure water only free silica is removed. In the range from 0.02 to 0.5 per cent. acid, both bases and silica go into solution and recombine as an aluminosilicate sol and as highly soluble salts. The sol recovered by evaporation, washing and drying is an amorphous colloid near pyrophyllite in composition, Al(2)O(3).mSiO(2).nH(2)O, with m averaging 4.1 (3.9 to 4.5) and n about 1.5. The slight variation in m is unrelated to either sol, acid or clay concentration. A general characteristic relation between the amount of sol formed and the amounts of clay, acid and water used has been found for montmorillonite clays. This relation differs in two essential properties from that previously deduced for halloysite-allophane solutions. The variation with temperature of the constants of these equations remains to be investigated. PMID:17740756

Nutting, P G

1945-06-15

287

Preparation of anion-exchange resins from pine sulfuric acid lignin, one of the acid hydrolysis lignins  

Microsoft Academic Search

To utilize acid hydrolysis lignin effectively, chemical conversion to anion-exchange resin was investigated by two methods. Sulfuric acid lignin (SAL) was selected as a typical acid hydrolysis lignin in this experiment. Because it is less reactive, SAL was phenolated with sulfuric acid catalyst to yield reactive phenolized SAL (P-SAL) with p-hydroxyphenyl nuclei. One method was the restricted resinification of P-SAL

Yasuyuki Matsushita; Seiichi Yasuda

2003-01-01

288

Variation of S\\/G ratio and lignin content in a Populus family influences the release of xylose by dilute acid hydrolysis  

Microsoft Academic Search

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\\u000a 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\\u000a ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions were

Brian H. Davison; Sadie R. Drescher; Gerald A. Tuskan; Mark F. Davis; Nhuan Phu Nghiem

2006-01-01

289

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

Microsoft Academic Search

Wood samples from a second generation Populus cross were shown to have different lignin contents and S\\/G ratios (S: syringyl-like lignin structures; G: guaiacyl-like lignin\\u000a 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\\u000a ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions

BRIAN H. DAVISONp; SADIE R. DRESCHERp; Gerald A. Tuskan; Mark F. Davis; Nhuan P. Nghiem

290

Atmospheric leaching of EAF dust with diluted sulphuric acid  

Microsoft Academic Search

In this study the hydrometallurgical processing of EAF steelmaking dust (Paul Wurth S.A.) is investigated on a laboratory scale under normal temperature and pressure conditions. The behaviour of zinc and iron under the influence of sulphuric acid as the leaching agent is discussed. The dependency between the temperature and the liquid\\/solid ratio is investigated. The main aim is the transfer

Tomas Havlik; Martina Turzakova; Srecko Stopic; Bernd Friedrich

2005-01-01

291

Process for the manufacture of sulfur or sulfuric acid from coke oven gas  

Microsoft Academic Search

A process for the complete elimination of ammonia and hydrogen sulfide from coke oven gases is described which does not lead to the occurrence of sulfur dioxide-containing condensates as in prior-art methods. Most of the hydrogen sulfide combustion gases are cooled only to the point where elementary sulfur condenses out on the cooler bottom. The process initially involves scrubbing the

G. Wunderlich; H. Weber

1974-01-01

292

Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation  

NASA Astrophysics Data System (ADS)

Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

2006-03-01

293

Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation  

NASA Astrophysics Data System (ADS)

Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the inferred mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

2006-08-01

294

On the Purity of Laboratory-Generated Sulfuric Acid Droplets and Ambient Particles Studied by Laser Mass Spectrometry  

Microsoft Academic Search

Particle analysis by laser mass spectrometry (PALMS) was used to examine sulfuric acid particles representative of stratospheric sulfate aerosols (SSAs) and ambient tropospheric aerosols. Sulfuric acid particles were generated in the laboratory by condensing sulfuric acid vapors in a flow stream of particle-free dry air or nitrogen. The purest particles were produced using filtered, high-purity nitrogen in a clean glass

Ann M. Middlebrook; David S. Thomson; Daniel M. Murphy

1997-01-01

295

Benefits of the stirred, autorefrigerated reactor in sulfuric acid alkylation  

SciTech Connect

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.

Ackerman, S.; Lerner, H.; Zaczepinski, S. [Exxon Research and Engineering Co., Florham Park, NJ (United States)

1996-12-01

296

Sulfuric acid: heat of formation of aqueous solutions by rotating-bomb calorimetry  

Microsoft Academic Search

Rotating-bomb calorimetry of rhombic sulfur, mixed with hydrocarbon oil in widely varying proportions, led to a more accurate value of the heat of combustion. The heat of formation of aqueous sulfuric acid was calculated from the measured value of the heat of combustion. For formation of HSO . 115HO(liq.) from rhombic sulfur, gaseous hydrogen and oxygen, ..delta..Hf.° is -212.17 +-

W. D. Good; J. L. Lacina; J. P. McCullough

1960-01-01

297

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

SciTech Connect

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.

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

298

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

PubMed Central

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

2011-01-01

299

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

SciTech Connect

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.

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

2008-04-01

300

Amine Reactivity with Nanoclusters of Sulfuric Acid and Ammonia  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

301

Dilute oxalic acid pretreatment for biorefining giant reed ( Arundo donax L.)  

Microsoft Academic Search

Biomass pretreatment is essential to overcome recalcitrance of lignocellulose for ethanol production. In the present study we pretreated giant reed (Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic acid. The effects of temperature (170190C), acid loading (210% w\\/w) and reaction time (1540min) were handled as a single parameter, combined severity. We explored the change in hemicellulose, cellulose

Danilo Scordia; Salvatore L. Cosentino; Jae-Won Lee; Thomas W. Jeffries

2011-01-01

302

Catalytic activities of cobalt, nickel and copper ferrospinels for sulfuric acid decomposition: The high temperature step in the sulfur based thermochemical water splitting cycles  

Microsoft Academic Search

The catalytic decomposition of sulfuric acid is the most endothermic step of the sulfur based water splitting thermochemical cycles, which are promising technologies for large scale hydrogen production in future. In the present study the catalytic activities of three ferrospinels AFe2O4 (A=Co, Ni, Cu) were evaluated for high temperature sulfuric acid decomposition reaction. Catalyst characterization by Mssbauer spectroscopy confirmed the

A. M. Banerjee; M. R. Pai; S. S. Meena; A. K. Tripathi; S. R. Bharadwaj

2011-01-01

303

Projection of 1985 market potential for FGD (flue gas desulfurization) byproduct sulfur and sulfuric acid in the US. Final report Jan 79Apr 80  

Microsoft Academic Search

The report projects the 1985 market potential for flue gas desulfurization (FGD) byproduct sulfur and sulfuric acid in the U.S. The projection is 165,000 tons of sulfur from 11 power plants and 554,000 tons of acid from 6 power plants, with a combined benefit to the affected industries of $20 million. FGD technology improvements and cost increases, particularly for fuel

W. E. OBrien; W. L. Anders; J. D. Veitch

1980-01-01

304

Accurate determination of sulfur in gasoline and related fuel samples using isotope dilution ICP-MS with direct sample injection and microwave-assisted digestion.  

PubMed

Inductively coupled plasma isotope-dilution mass spectrometry (ICP-IDMS) with direct injection of isotope-diluted samples into the plasma, using a direct injection high-efficiency nebulizer (DIHEN), was applied for accurate sulfur determinations in sulfur-free premium gasoline, gas oil, diesel fuel, and heating oil. For direct injection a micro-emulsion consisting of the corresponding organic sample and an aqueous 34S-enriched spike solution with additions of tetrahydronaphthalene and Triton X-100, was prepared. The ICP-MS parameters were optimized with respect to high sulfur ion intensities, low mass-bias values, and high precision of 32S/34S ratio measurements. For validation of the DIHEN-ICP-IDMS method two certified gas oil reference materials (BCR 107 and BCR 672) were analyzed. For comparison a wet-chemical ICP-IDMS method was applied with microwave-assisted digestion using decomposition of samples in a closed quartz vessel inserted into a normal microwave system. The results from both ICP-IDMS methods agree well with the certified values of the reference materials and also with each other for analyses of other samples. However, the standard deviation of DIHEN-ICP-IDMS was about a factor of two higher (5-6% RSD at concentration levels above 100 mircog g(-1)) compared with those of wet-chemical ICP-IDMS, mainly due to inhomogeneities of the micro-emulsion, which causes additional plasma instabilities. Detection limits of 4 and 18 microg g(-1) were obtained for ICP-IDMS in connection with microwave-assisted digestion and DIHEN-ICP-IDMS, respectively, with a sulfur background of the used Milli-Q water as the main limiting factor for both methods. PMID:15232670

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

2004-09-01

305

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

306

Hydrogen and sulfuric acid production by electrolysis with anodic depolarization by sulfurous anhydride  

Microsoft Academic Search

Practical aspects of improving the efficiency of water electrolysis with anodic depolarization by sulfurous anhydride in an\\u000a electrolyzer with a solid polymeric electrolyte are discussed. Methods of reducing energy outlays for the production of hydrogen,\\u000a for example, by altering the organization of the feed of sulfurous anhydride to the reaction zone, are proposed and implemented.\\u000a This made it possible to

V. I. Kostin; V. N. Fateev; D. A. Bokach; S. V. Korobtsev; A. V. Kozolii; S. E. Salnikov

2008-01-01

307

A palladium-catalyzed three-component coupling of arylboronic acids, sulfur dioxide and hydrazines.  

PubMed

A novel and efficient route to aryl N-aminosulfonamides via a palladium-catalyzed three-component coupling of arylboronic acids, sulfur dioxide and hydrazines in the presence of a balloon of dioxygen is reported. The reaction proceeded smoothly under mild conditions and DABCO(SO(2))(2) was used as the source of sulfur dioxide. PMID:22743613

Ye, Shengqing; Wu, Jie

2012-08-11

308

Phase transitions in a bed of vanadium catalyst for sulfuric acid production: experiment and modeling  

Microsoft Academic Search

Sulfur dioxide oxidation on vanadium catalysts in sulfuric acid production may cause phase transitions in the catalyst active component. These phase transitions involve crystallization of vanadium(IV), and may influence catalyst activity. In the present study, we show that reaction mixture flow through a fixed catalyst bed is accompanied by the moving front of crystal phase, which decreases SO2 conversion at

B. S. Balzhinimaev; N. P. Belyaeva; S. I. Reshetnikov; E. S. Yudina; A. A. Ivanov

2001-01-01

309

Kinetics of gypsum formation and growth during the dissolution of colemanite in sulfuric acid  

Microsoft Academic Search

One of the most important boron minerals, colemanite, is dissolved in aqueous sulfuric acid to produce boric acid whereby gypsum is formed as byproduct. Filtration of gypsum has an important role in boric acid production because gypsum affects the efficiency, purity and crystallization of boric acid. The formation and growth kinetics of gypsum during the dissolution of colemanite in aqueous

E. etin; ?. Ero?lu; S. zkar

2001-01-01

310

Determination of Key Intermediates in Cholesterol and Bile Acid Biosynthesis by Stable Isotope Dilution Mass Spectrometry  

PubMed Central

For more than a decade, we have developed stable isotope dilution mass spectrometry methods to quantify key intermediates in cholesterol and bile acid biosynthesis, mevalonate and oxysterols, respectively. The methods are more sensitive and reproducible than conventional radioisotope (RI), gas-chromatography (GC) or high-performance liquid chromatography (HPLC) methods, so that they are applicable not only to samples from experimental animals but also to small amounts of human specimens. In this paper, we review the development of stable isotope dilution mass spectrometry for quantifying mevalonate and oxysterols in biological materials, and demonstrate the usefulness of this technique.

Yoshida, Tadashi; Honda, Akira; Miyazaki, Hiroshi; Matsuzaki, Yasushi

2008-01-01

311

Sulfuric Acid Mist Generation in Utility Boiler Flue Gas  

Microsoft Academic Search

Sulfur Dioxide (SO2), Sulfur Trioxide (SO3) and Oxides of Nitrogen, mainly NO and NO2, are generated during the combustion of certain fossil fuels. Electric power generating units contribute more than 70% of the national SOx emissions (1). When significant volumes of flue gas containing these oxides are discharged to the atmosphere, various state or local authorities set standards for the

Boris Altshuler

312

Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design  

Microsoft Academic Search

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

Michael S. Peck

2007-01-01

313

Temperature and intensity of sonoluminescence radiation in sulfuric acid  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

314

Temperature and intensity of sonoluminescence radiation in sulfuric acid.  

PubMed

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. PMID:23005534

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

2012-07-01

315

Effects of Large (0.9 micrometer) Sulfuric Acid Aerosols on Human Pulmonary Function.  

National Technical Information Service (NTIS)

The effects of sulfuric acid particle concentration (mass/volume) and ambient temperatures on pulmonary function of young male nonsmokers were examined. Subjects (n=11) thrice repeated a sequence of 20-min exercise (ventilation approximately 30 liters/min...

S. M. Horvath L. J. Folinsbee J. F. Bedi

1982-01-01

316

Sorption of Uranium from Sulfuric Acid Leaching Solutions by Strongly Basic Anion Exchangers  

Microsoft Academic Search

The equilibrium and kinetic characteristics of uranium sorption from simulated sulfuric acid leaching solutions by AMP, Lewatit K 6367, Purolite A 500, Purolite A 600, and AM-p gel-like and porous strongly basic anion exchangers were studied.

D. N. Kolomiets; I. D. Troshkina; M. F. Sheremetev; L. V. Konopleva

2005-01-01

317

Sulfuric Acid Nucleation with NH3, Methyl, Dimethyl, and Trimethyl Amines  

NASA Astrophysics Data System (ADS)

Nucleation of particles from sulfuric acid, water, and nitrogen base molecules was studied within a cylindrical flow reactor. The particles formed from these vapors were detected with a nano Mobility Particle Sizer coupled to a Diethylene Glycol Ultrafine Condensation Particle Counter. The effects of ammonia and small alkyl amines on particle formation with sulfuric acid vapor were very large. Enhancements of particle numbers by factors of thousands to millions indicates that these species have powerful effects on nucleation of sulfuric acid molecules. Power dependencies for particle numbers on sulfuric acid and nitrogen bases elucidates the chemical content of the critical clusters and this helps to shed light on the nucleation mechanisms. The details of the particle detection efficiencies, information on the extent of particle growth, and independently determined cluster thermodynamics help to verify these results and to extrapolate them to atmospheric conditions.

Hanson, D. R.; Volz, K.; Glasoe, W.; Panta, B.

2013-12-01

318

Solvent free Tetrahydropyranylation of Alcohols and Phenols over Sulfuric Acid Adsorbed on Silica Gel  

Microsoft Academic Search

Alcohols and phenols are tetrahydropyranylated in the presence of sulfuric acid adsorbed on silica gel in high to excellent yields in solvent free conditions and is expedited by microwave irradiation. Addition of methanol performs the complete deprotection.

Majid M. Heravi; Dariush Ajami; Mitra Ghassemzadeh

1999-01-01

319

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

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

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

2010-01-01

320

Weak boundary layers on vulcanized styrenebutadiene rubber treated with sulfuric acid  

Microsoft Academic Search

A synthetic vulcanized styrene-butadiene rubber (R2) was used in this study. The presence of paraffin wax and zinc stearate in the rubber composition prevented the adhesion of R2 rubber to solvent-based polyester-urethane adhesive. To increase the adhesion properties of R2 rubber, a surface treatment with sulfuric acid (cyclization) was applied, and the length of the immersion in sulfuric acid and

Carmen M. Cepeda-Jimnez; M. Mercedes Pastor-Blas; Jos Miguel Martn-Martnez

2001-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

322

Investigation of optimal conditions for zinc electrowinning from aqueous sulfuric acid electrolytes  

Microsoft Academic Search

Results are reported of an experimental investigation of the effects of aqueous zinc(II) and sulfuric acid concentrations\\u000a on current efficiencies and deposit morphologies of metallic zinc, aimed at designing a process for zinc recovery from solid\\u000a industrial wastes by leaching and electrodeposition. Voltammetry and chronopotentiometry of additive-free solutions of zinc(II)\\u000a sulfate and sulfuric acid were used to determine the zinc(II)

P. Guillaume; N. Leclerc; C. Boulanger; J. M. Lecuire; Franois Lapicque

2007-01-01

323

The reaction between solid UO 2 and MnO 2 in a sulfuric acid solution  

Microsoft Academic Search

In connection with the extensive use of pyrolusite in the sulfuric acid leaching of uranium from ores, a study was made of the reaction between UO2 and MnO2 in a sulfuric acid solution,and possible mechanisms were discussed. The experimental data show that the reaction apparently occurs at the points of contact of the hydrated surface layers of UO2 and MnO2;

E. A. Kanevskii; V. A. Pchelkin

1961-01-01

324

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

Microsoft Academic Search

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

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

1980-01-01

325

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

NASA Technical Reports Server (NTRS)

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.

Palmer, K. F.; Williams, D.

1975-01-01

326

Determination of Sulfuric Acid, Oxalic Acid, and Their Matrix Effects in Aluminum Anodizing Solutions by Ion Chromatography.  

National Technical Information Service (NTIS)

Anodizing and hardcoating (hard anodizing) of aluminum improve corrosion and wear resistance. Acid concentrations (sulfuric, oxalic), pH, and physical plating variables (current, temperature, time) affect oxide coating thickness, porousness, hardness, sol...

S. Sopok

1988-01-01

327

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

PubMed

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. PMID:21723268

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

2011-10-01

328

Study of vibrational spectra of polyaniline doped with sulfuric acid and phosphoric acid.  

PubMed

Vibrational spectra of insulator emeraldine base (EB) form of polyaniline and electrical conductive sulfuric acid- and phosphoric acid-doped emeraldine salts (ES) were studied in the region of 4000-400 cm(-1) at ambient temperature by Fourier transform infrared spectroscopy. Infrared transmittance spectra of EB and ES were investigated to understand the bonding behavior of different organic and inorganic groups present in the polymeric chains and their structural variations on protonation by sulfate or phosphate ion inclusion in the polymer salt network. These studies revealed the para-coupling of deformed disubstituted benzenoid (B) and quinoid (Q) rings with ends capped predominantly by (B4Q1) units. The deformation of B and Q rings was confirmed by the appearance of many weak bands, very weak bands, and satellite structures in strong transmittance peaks of polymeric chain-constituting groups. Protonation takes place at the nitrogen sites of Q rings and forms semiquinone radical ions in ES. The vibrational bands pertaining to B rings, Q rings, B4Q1 units, semiquinone segment, sulfate ions, and phosphate ions were observed and assigned from these measurements. The shift in peak position of some bands with gain or loss in intensity and appearance of some new bands were observed in sulfuric acid- and phosphoric acid-doped ES spectra. These variations are attributed to the formation of new structural groups in ES on protonation and a change in crystalline field by sulfate and phosphate ion doping for crosslinking the polymeric chains. PMID:11783885

Arora, M; Luthra, V; Singh, R; Gupta, S K

2001-01-01

329

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

330

Backscatter laser depolarization studies of simulated stratospheric aerosols: crystallized sulfuric acid droplets  

SciTech Connect

The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 /mu/m) 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 /delta/ /approx/ 0.02, but /delta/ /approx/ 0.10--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 /delta/ /approx/ 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (/delta/ /approx/ 0) or ice crystal (/delta/ /approx/ 0.5) clouds.

Sassen, K.; Zhao, H.; Yu, B.

1989-08-01

331

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

332

Recovery of Zinc and Sulfur from Sphalerite Concentrates by Reaction with Sulfuric Acid.  

National Technical Information Service (NTIS)

The Bureau of Mines constructed a process research unit (PRU) to demonstrate new technology for extracting zinc from sphalerite concentrates. Up to 9 kg/hr of sphalerite (ZnS) concentrate was reacted at ambient pressure in the PRU with 80 pct sulfuric aci...

A. A. Cochran H. H. Dewing S. E. Lay

1982-01-01

333

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

SciTech Connect

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.

Gorensek, M.; Edwards, T.

2009-06-11

334

Commercial double-indicator-dilution densitometer using heavy water: Evaluation in oleic-acid pulmonary edema  

Microsoft Academic Search

We evaluated a commercially available, double-indicator-dilution densitometric system for the estimation of pulmonary extravascular\\u000a water volume in oleic acid-induced pulmonary edema. Indocyanine green and heavy water were used as the nondiffusible and diffusible\\u000a tracers, respectively. Pulmonary extravascular water volume, measured with this system, was 67% of the gravimetric value (r = 0.91), which was consistent with values obtained from the

Lars G. Leksell; Mark S. Schreiner; Angelina Sylvestro; Gordon R. Neufeld

1990-01-01

335

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

Microsoft Academic Search

The effectiveness of coagulation (using aluminium-based chemicals and ferrous sulfate) and acid precipitation (using H2SO4) 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)

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

2010-01-01

336

Sulfuric acid rain effects on crop yield and foliar injury. Final report  

SciTech Connect

A study was undertaken to determine the relative sensitivity of major U.S. crops to sulfuric acid rain. Plants were grown under controlled environmental conditions and exposed to simulated acid rain of three sulfuric acid concentrations (pH 3.0, 3.5, 4.0) or to a control rain (pH 5.7). Injury to foliage and effects on yield were common responses to acid rain. However, foliar injury was not a good indicator of effects on yield.

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

1980-01-01

337

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

338

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

PubMed Central

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 56.20g/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.

2014-01-01

339

Leaching kinetics of the magnetic fraction of converter matte in sulfuric acid and hydrochloric acid solutions  

NASA Astrophysics Data System (ADS)

The kinetic peculiarities of the dissolution of the magnetic fraction of converter matte in H2SO4 (150 g/l) and HCl (200 g/l) solutions are studied in the temperature range of 30-90C. Under comparable conditions, the dissolution rate of the magnetic fraction of converter matte in HCl solutions is shown to be substantially higher than that in H2SO4 solutions. The kinetic parameters of the processes under study are calculated. It is found that the dissolution of the magnetic fraction of converter matte in a sulfuric acid solution occurs within a diffusion range ( E a 6.5 kcal/mol), whereas the dissolution in a hydrochloric acid solution corresponds to a kinetic range ( E a 15 kcal/mol). Possible mechanisms of the dissolution of the magnetic fraction of converter matte in mineral acid solutions are considered.

Palant, A. A.; Bryukvin, V. A.; Tsibin, O. I.; Paretskii, V. M.

2010-12-01

340

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

NASA Astrophysics Data System (ADS)

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 ?CO2 and ?T and were far above the local ambient atmospheric background-level of typically 15-50 pptv. Our observations indicate a lower limit for the efficiency ? for fuel-sulfur conversion to SA of 0.34 %.

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

341

Engineering design of a thermochemical water-splitting cycle. Quarterly report, September 1November 30, 1975. [Sulfuric acid-sulfur oxide-sulfide cycle  

Microsoft Academic Search

The flowsheet and heat and mass balance calculations for the Los Alamos baseline sulfuric acid-sulfur-oxide-sulfide cycle have been completed. The overall efficiency is 27 percent, based on the higher heating value of hydrogen. This value includes the heat required to supply power for helium circulators of the nuclear heat source and the compression of the product hydrogen to 70 atm.

J. DeGraaf; J. Porter; J. Russell

1975-01-01

342

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

PubMed Central

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

Legisa, M; Gradisnik-Grapulin, M

1995-01-01

343

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

NASA Technical Reports Server (NTRS)

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.

1985-01-01

344

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

NASA Technical Reports Server (NTRS)

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.

Carlson, R. W.

2004-01-01

345

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

346

Ionic Liquids as Catalysts for Sulfuric Acid Production and Cleaning of Flue Gases  

Microsoft Academic Search

\\u000a The present paper is concerned with catalytic pollution abatement of sulfur and nitrogen oxides in flue gases from industrial\\u000a sources. Especially fundamental and applied research on industrial catalysts and their model systems is presented with regards\\u000a to cleaning of flue gases from fossil fuel based power plants and plants producing sulfuric acid. Combined DeSOx and DeNOx processes are very common

Rasmus Fehrmann; K. M. Eriksen; S. B. Rasmussen; J. Winnick

347

An enhanced throughput method for quantification of sulfur mustard adducts to human serum albumin via isotope dilution tandem mass spectrometry.  

PubMed

Here, we report an enhanced throughput method for the diagnosis of human exposure to sulfur mustard. A hydroxyethylthioethyl (HETE) ester-adducted tripeptide, produced by pronase digestion of human serum albumin, was selected as the quantitative exposure biomarker. Cibacron Blue enrichment was developed from an established cartridge method into a 96-well plate format, increasing throughput and ruggedness. This new method decreased sample volume 2.5-fold. Addition of a precipitation and solid-phase extraction concentration step increased the sensitivity of the method. With the conversion to a 96-well plate and optimization of chromatography, the method resulted in a 3-fold decrease in analysis time. Inclusion of a confirmation ion has increased specificity. The method was found to be linear between 0.050 and 50 M sulfur mustard exposure with a precision for both quality control samples of ?6.5% relative standard deviation and an accuracy of >96%. The limit of detection (3So) was calculated to be ?0.0048 M, an exposure value similar to that of the HETE-albumin adduct method first described by Noort and co-workers (Noort et al., 1999; Noort el al., 2004) which used protein precipitation to isolate albumin. A convenience set of 124 plasma samples from healthy unexposed individuals was analyzed using this method to assess background levels of exposure to sulfur mustard; no positive results were detected. PMID:24201816

Andacht, Tracy M; Pantazides, Brooke G; Crow, Brian S; Fidder, Alex; Noort, Daan; Thomas, Jerry D; Blake, Thomas A; Johnson, Rudolph C

2014-01-01

348

Specifics of the sulfuric-acid processing of galena concentrates in the presence of nitrous acid  

Microsoft Academic Search

Conclusions\\u000a \\u000a \\u000a \\u000a 1.\\u000a \\u000a Nitrous acid has a catalytic effect on the sulfuric-acid decomposition of galena. With oxygen at atmospheric pressure, the\\u000a presence of even small quantities of HNO2 in the solution (0.01 M) at room temperature increases the degree of oxidation of lead sulfide twofold.\\u000a \\u000a \\u000a \\u000a \\u000a 2.\\u000a \\u000a The solid products of the oxidation of PbS (PbSO4 and S) form a dense film

T. I. Markovich; A. B. Ptitsyn

1998-01-01

349

About the stability of sulfurous acid (H2SO3) and its dimer.  

PubMed

The characterization and isolation of sulfurous acid (H2SO3) have never been accomplished and thus still remain one of the greatest open challenges of inorganic chemistry. It is known that H2SO3 is thermodynamically unstable. In this study, however, we show that a Ci-symmetric dimer of sulfurous acid (H2SO3)2 is 3.5 kcal mol-1 more stable than its dissociation products SO2 and H2O at 77 K. Additionally, we have investigated the kinetic stability of the sulfurous acid monomer with respect to dissociation into SO2 and H2O and the kinetic isotope effect (KIE) on this reaction by transition-state theory. At 77 K, the half-life of H2SO3 is 15 x 10(9) years, but for the deuterated molecule (D2SO3) it increases to 7.9 x 10(26) years. At room temperature, the half-life of sulfurous acid is only 24 hours; however, a KIE of 3.2 x 10(4) increases it to a remarkable 90 years. Water is an efficient catalyst for the dissociation reaction since it reduces the reaction barrier tremendously. With the aid of two water molecules, one can observe a change in the reaction mechanism for sulfurous acid decomposition with increasing temperature. The most likely mechanism below 170 K is via an eight-membered transition-state ring; yet, above 170 K, a mechanism with a six-membered transition state ring becomes the predominant one. For deuterated sulfurous acid, this change in reaction mechanism can be observed at 120 K. Consequently, between 120 and 170 K, different predominant reaction mechanisms occur for the decomposition of normal and deuterated sulfurous acid when assisted by two water molecules. However, the much longer half-life of deuterated sulfurous acid and the stability of the sulfurous acid dimer at 77 K are encouraging for future synthesis and characterization under laboratory conditions. PMID:12693045

Voegele, Andreas F; Tautermann, Christofer S; Loerting, Thomas; Hallbrucker, Andreas; Mayer, Erwin; Liedl, Klaus R

2002-12-16

350

KINETICS OF DISSOLUTION OF UO IN SULFURIC ACID. Technical Report No. XXVIII  

Microsoft Academic Search

The leaching of UO in sulfuric acid solutions was investigated ; and the rate of leaching was measured by determining the concentration of UO\\/sub ; 2\\/\\/sup ++\\/ in solution as a function of time. The rate was determined as a ; function of the agitation of the solution, acid concentration, and overpressure ; of oxygen. A mechanism was postulated that

T. L. Mackay; M. E. Wadsworth

1957-01-01

351

Genetic and environmental factors involved in increased resistance of brook trout to sulfuric acid solutions and mine acid polluted waters  

Microsoft Academic Search

Several strains of hatchery-reared brook trout, Salvelinus fontinalis (Mitchill), were exposed to low pH in the laboratory (sulfuric acid solutions) and in the field (mine acid polluted waters). Wild brook trout were also used in some field tests. Tests were both acute and chronic (up to 2 mo). Pronounced strain differences in survival ability were detected among embryonic, juvenile, and

FREDERICK A. SWARTS; WILLIAM A. DUNSON; JAMES E. WRIGHT

1978-01-01

352

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

PubMed

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. PMID:19936975

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

2009-12-01

353

Sonoluminescence of Alkali-Metal Atoms in Sulfuric Acid: Comparison with That in Water  

NASA Astrophysics Data System (ADS)

Intense orange Na* emission was observed in different spatial locations from blue emission during multibubble sonoluminescence in sulfuric acid. The color change from blue to orange was observed along the streamer in the filamentous structure of a bubble cloud. By stroboscopic observation, the Na* emission seemed to occur when a large bubble ejected tiny bubbles at the positions toward a pressure node after bubble coalescence around a pressure antinode. The intensity of Na* emission in the sulfuric acid case increased at lower frequency in contrast with the water case. By comparing a high-resolution Na* spectrum of sulfuric acid with that of water, the widths of the spectra were almost the same, except for something being superimposed in the water case. The estimations of the temperature and pressure inside the Na* emission bubbles at 28 and 150 kHz were 1900 K and 100 atm and 2200 K and 150 atm, respectively.

Shin-ichi Hatanaka,; Shigeo Hayashi,; Pak-Kon Choi,

2010-07-01

354

Fractionation of Cynara cardunculus (Cardoon) Biomass by Dilute-Acid Pretreatment  

NASA Astrophysics Data System (ADS)

Cynara cardunculus L. (cardoon) is a Mediterranean perennial herb offering good potential as substrate for sustainable production of bioethanol. In this work the first approach to the study of dilute-acid pretreatment of cardoon biomass for biological conversion was made. The influence of temperature (160-200C), acid concentration (0-0.2% [w/w]), and solid concentration (5-10% [w/v]) in the formation of free sugars and sugar decomposition products in the prehydrolyzate was studied using a response surface methodology. Results show a negative interaction effect between acid concentration and temperature in xylose recovery yield in prehydrolyzate, whereas dry matter concentration does not exert a significant effect. Xylose recovery yield reaches a maximum of about 80% of the content in dry untreated raw material at 180C and 0.1 or 0.2% acid addition. At these conditions the ratio of monomers found in prehydrolyzate in relation to total sugar yield for xylose is close to 100%. Furfural concentration, the major furan determined in the prehydrolyzate, increases as pretreatment severity rises. Maximum furfural yield of 4.2 g/100 g dry untreated raw material was found at 200C and 0.2% acid concentration. The yield of furfural at the conditions in which maximum xylose recovery is attained is substantially lower, less than 2 g/100 g dry untreated raw material. This fact supports the idea of using moderate temperatures in dilute-acid processes, which at the same time provides reasonably high sugar recovery yield and avoids high inhibitory products formation.

Ballesteros, Mercedes; Negro, M. Jos; Manzanares, Paloma; Ballesteros, Ignacio; Sez, Felicia; Oliva, J. Miguel

355

Ethanol production from hexoses, pentoses, and dilute-acid hydrolyzate by Mucor indicus.  

PubMed

Consumption of hexoses and pentoses and production of ethanol by Mucor indicus were investigated in both synthetic media and dilute-acid hydrolyzates. The fungus was able to grow in a poor medium containing only carbon, nitrogen, phosphate, potassium, and magnesium sources. However, the cultivation took more than a week and the ethanol yield was only 0.2 gg(-1). Enrichment of the medium by addition of trace metals, particularly zinc and yeast extract, improved the growth rate and yield, such that the cultivation was completed in less than 24 h and the ethanol and biomass yields were increased to 0.40 and 0.20 gg(-1), respectively. The fungus was able to assimilate glucose, galactose, mannose, and xylose, and produced ethanol with yields of 0.40, 0.34, 0.39, and 0.18 gg(-1), respectively. However, arabinose was poorly consumed and no formation of ethanol was detected. Glycerol was the major by-product in the cultivation on the hexoses, while formation of glycerol and xylitol were detected in the cultivation of the fungus on xylose. The fungus was able to take up the sugars present in dilute-acid hydrolyzate as well as the inhibitors, acetic acid, furfural, and hydroxymethyl furfural. M. indicus was able to grow under anaerobic conditions when glucose was the sole carbon source, but not on xylose or the hydrolyzate. The yield of ethanol in anaerobic cultivation on glucose was 0.46 g g(-1). PMID:15780667

Sues, Anna; Millati, Ria; Edebo, Lars; Taherzadeh, Mohammad J

2005-04-01

356

Formation of UV-vis Absorbing Organic Solutes, Films, and Suspended Precipitates in Sulfuric Acid Solutions at Stratospheric Aerosol Acidities  

NASA Astrophysics Data System (ADS)

The stratospheric aerosol layer has traditionally been thought of as being composed of pure sulfuric acid/water aerosols, but recent airborne measurements of single particle composition (e.g. Murphy et al. 2007) have shown that 10-20% of sampled aerosols in the lower stratosphere have significant organic content. Since there is very little water vapor in the stratosphere, these sulfuric acid/organic particles will be extremely acidic (40-80 wt% sulfuric acid). Here we show that small amounts (approx. 0.1wt%) of carbonyl compounds allowed to react with such concentrated sulfuric acid solutions produce highly-colored solutions that continue to darken for months after mixing. We examined propanal, methylglyoxal, and glyoxal singly as well as in various combinations. In the case of propanal, colored organic films form on the surfaces of the solutions on a timescale of days to weeks depending on acidity. Solutions of various compositions also formed precipitates suspended near the liquid surface. UV-vis absorption spectra of the colored solutions will be presented along with kinetics of film formation as a function of acidity, temperature, and organic content. These results will be used to assess whether it is possible that such films could exist in the lower stratosphere (or upper troposphere) in quantities that would be significant enough to impact the direct and/or indirect climate forcing of these aerosols and/or satellite retrievals of atmospheric species that employ UV-vis wavelengths.

van Wyngarden, A. L.; Belle, C. L.; Dalle Ore, C. L.; Morrissey, M. J.; Rodgers, J. M.; Iraci, L. T.

2009-12-01

357

Multiple-acid equilibria in adsorption of carboxylic acids from dilute aqueous solution  

SciTech Connect

Equilibria were measured for adsorption of carboxylic acids from aqueous, binary-acid mixtures of lactic and succinic acids and acetic and formic acids onto basic polymeric sorbents. The experimentally determined adsorption isotherms compared well with model predictions, confirming that simple extensions from adsorption of individual acids apply. Fixed-bed studies were carried out that establish the efficacy of chromatographic fractionation of lactic and succinic acids using basic polymeric sorbents. Finally, sequential thermal and solvent regeneration of lactic and acetic acid-laden sorbents was investigated as a method to fractionate among coadsorbed volatile and nonvolatile acids. Essentially complete removal of the acetic acid from the acid-laden sorbent was achieved by vaporization under the conditions used; a small amount of loss of lactic acid (about 11%) was observed.

Husson, S.M.; King, C.J. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

1999-02-01

358

Plotting of Acid Rain and Sulfur Dioxide Pollution Control Zones and Integrated Control Planning in China  

Microsoft Academic Search

The distribution and characteristics of acid rain and SO2 pollution were presented, indicating that the areas with sulfur deposition over critical loads reached 21.9% of the territory in 1995. In order to control the acid rain and SO2 pollution effectively, the Acid Rain Control Zone and SO2 Pollution Control Zone (Two Control Zones for short) were designated based on the

Jiming Hao; Shuxiao Wang; Bingjiang Liu; Kebin He

2001-01-01

359

Sulfuric acid and leaching requirements for reclaiming sodium-affected calcareous soils  

Microsoft Academic Search

SummaryThe changes in exchangeable sodium and total dissolved salts due to the application of sulfuric acid and water to sodium-affected\\u000a calcareous soils were studied for the purpose of establishing a convenient way of determining acid and leaching water requirements.\\u000a Conventional methods which ignore the effect of sodium removed from soil exchange sites are inadequate for estimating amounts\\u000a of acid needed

S. Miyamoto; R. J. Prather; J. L. Stroehlein

1975-01-01

360

A modification of the phenol\\/sulfuric acid assay for total carbohydrates giving more comparable absorbances  

Microsoft Academic Search

The conditions and acid strength of the phenol\\/sulfuric acid assay were investigated to improve agreement between absorbances\\u000a obtained from different sugars. It was found that by increasing acid strength and by cooling the tubes in water after a short\\u000a reaction time, the values obtained for several sugars, including fructose and xylose, agreed, on an equimolar value, with\\u000a that for glucose.

Kimberley A. C. C. Taylor

1995-01-01

361

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

PubMed

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. PMID:21463933

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

2011-05-01

362

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

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.

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

2004-08-01

363

Comments on determination of sulfuric acid and ammonium sulfates by means of computer-controlled thermodenuder system  

SciTech Connect

Slanina et al. have made an important advance in the measurement of sulfate aerosols with their highly sensitive thermodenuder system. In this instrument air is drawn through 120 /sup 0/C and 220 /sup 0/C denuders connected in series, and particulate sulfuric acid and the ammonium sulfates are converted into sulfuric acid vapor, which is sorbed on the denuder walls. At the end of the sampling period each denuder is individually heated to 800 /sup 0/C, and the evolved SO/sub 2/, which results from decomposition of the sorbed sulfuric acid, is measured by a flame photometric detector. The purpose of this note is to clarify the speciation capabilities of the instrument and particularly the difference between volatilizable and titratable sulfuric acid. It will be assumed that only sulfuric acid, ammonium sulfate, and intermediate stoichiometries are present. Metal sulfates, organosulfur compounds, and other acidic and ammonium species (e.g., nitrates) are taken to be absent. 9 references.

Huntzicker, J.J.

1986-03-01

364

On-line control of fed-batch fermentation of dilute-acid hydrolyzates.  

PubMed

Dilute-acid hydrolyzates from lignocellulose are, to a varying degree, inhibitory to yeast. In the present work, dilute-acid hydrolyzates from spruce, birch, and forest residue, as well as synthetic model media, were fermented by Saccharomyces cerevisiae in fed-batch cultures. A control strategy based on on-line measurement of carbon dioxide evolution (CER) was used to control the substrate feed rate in a lab scale bioreactor. The control strategy was based solely on the ratio between the relative increase in CER and the relative increase in feed rate. Severely inhibiting hydrolyzates could be fermented without detoxification and the time required for fermentation of moderately inhibiting hydrolyzates was also reduced. The feed rate approached a limiting value for inhibiting media, with a corresponding pseudo steady-state value for CER. However, a slow decrease of CER with time was found for media containing high amounts of 5-hydroxymethyl furfural (HMF). The success of the control strategy is explained by the conversion of furfural and HMF by the yeast during fed-batch operation. The hydrolyzates contained between 1.4 and 5 g/l of furfural and between 2.4 and 6.5 g/l of HMF. A high conversion of furfural was obtained (between 65-95%) at the end of the feeding phase, but the conversion of HMF was considerably lower (between 12-40%). PMID:10861413

Taherzadeh, M J; Niklasson, C; Lidn, G

2000-08-01

365

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

PubMed

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

Pu, Yunqiao; Hu, Fan; Huang, Fang; Davison, Brian H; Ragauskas, Arthur J

2013-01-01

366

Improved Multivariate Calibration Models for Corn Stover Feedstock and Dilute-Acid Pretreated Corn Stover  

SciTech Connect

We have studied rapid calibration models to predict the composition of a variety of biomass feedstocks by correlating near-infrared (NIR) spectroscopic data to compositional data produced using traditional wet chemical analysis techniques. The rapid calibration models are developed using multivariate statistical analysis of the spectroscopic and wet chemical data. This work discusses the latest versions of the NIR calibration models for corn stover feedstock and dilute-acid pretreated corn stover. Measures of the calibration precision and uncertainty are presented. No statistically significant differences (p = 0.05) are seen between NIR calibration models built using different mathematical pretreatments. Finally, two common algorithms for building NIR calibration models are compared; no statistically significant differences (p = 0.05) are seen for the major constituents glucan, xylan, and lignin, but the algorithms did produce different predictions for total extractives. A single calibration model combining the corn stover feedstock and dilute-acid pretreated corn stover samples gave less satisfactory predictions than the separate models.

Wolfrum, E. J.; Sluiter, A. D.

2009-01-01

367

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

PubMed Central

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.

2013-01-01

368

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

Microsoft Academic Search

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

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

2008-01-01

369

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

PubMed

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. PMID:23708848

Lim, Woo-Seok; Lee, Jae-Won

2013-07-01

370

Materials development for thermochemical cycles: sulfuric acid vaporizer. Semiannual technical report, October 1, 1977March 31, 1978  

Microsoft Academic Search

Installation of a sulfuric acid corrosion test facility has been completed and is described. The facility is to be used for testing of potential materials for containment and heat exchange of a sulfuric acid vaporizer at temperatures up to 725K and boiling pressures of >20 atm (2 MPa). Materials that are ready for test are Duriron, Durichlor 51, single crystal

Krikorian

1978-01-01

371

Configuring the thermochemical hydrogen sulfuric acid process step for the Tandem Mirror reactor  

NASA Astrophysics Data System (ADS)

The sulfuric acid step was identified as the critical part of the thermochemical cycle in dictating the thermal demands and temperature requirements of the heat source. The general atomic sulfur-iodine cycle was coupled to a tandem mirror. The sulfuric acid decomposition process step was focused on specifically since this step can use the high efficiency electrical power of the direct converter together with the other thermal-produced electricity to Joule-heat a noncatalytic SO3 decomposer to approximately 1250 K. The blanket temperature was lowered to about 900 K, greatly alleviating materials problems, the level of technology required safety problems, and costs. A moderate degree of heat was integrated to keep the cycle efficiency around 48%, but the number of heat exchangers was limited in order to keep hydrogen production costs within reasonable bounds.

Galloway, T. R.

1981-05-01

372

Two bismuth sulfate-sulfuric acid hybrid water-splitting cycles. Proposed antimonyl sulfate cycle  

NASA Astrophysics Data System (ADS)

Two hybrid thermochemical cycles for the production of hydrogen which involve bismuth trisulfate and/or bismuth oxysulfates were investigated. Equilibrium sulfur trioxide pressure are given graphically for three solid gas equilibria involving Bi2(SO4)3 alpha- and beta-Bi2O(SO4)2, and Bi2O2SO4. An improved method of carrying out the low temperature step for Cycle 1 is presented which may provide a remedy to a problem of sorption of sulfuric acid solution by the solids. An antimonyl sulfate - sulfuric acid hybrid cycle is outlined in which SO2 and O2 are evolved at different temperatures, simplifying the usual SO3-SO2-O2 separation problem.

Jones, W. M.

373

Configuring the thermochemical hydrogen sulfuric acid process step for the Tandem Mirror Reactor  

SciTech Connect

This paper identifies the sulfuric acid step as the critical part of the thermochemical cycle in dictating the thermal demands and temperature requirements of the heat source. The General Atomic Sulfur-Iodine Cycle is coupled to a Tandem Mirror. The sulfuric acid decomposition process step is focused on specifically since this step can use the high efficiency electrical power of the direct converter together with the other thermal-produced electricity to Joule-heat a non-catalytic SO/sub 3/ decomposer to approximately 1250/sup 0/K. This approach uses concepts originally suggested by Dick Werner and Oscar Krikorian. The blanket temperature can be lowered to about 900/sup 0/K, greatly alleviating materials problems, the level of technology required, safety problems, and costs. A moderate degree of heat has been integrated to keep the cycle efficiency around 48%, but the number of heat exchangers has been limited in order to keep hydrogen production costs within reasonable bounds.

Galloway, T.R.

1981-05-01

374

Self-ordering of cell arrangement of anodic porous alumina formed in sulfuric acid solution  

Microsoft Academic Search

Self-ordering of the cell arrangement of the porous structure of anodic alumina has been studied in a sulfuric acid solution. Ordering of the cell arrangement was dependent on the applied potential, and a highly ordered structure was obtained under anodization at a constant potential of 25 to 27 V. Self-ordering of the porous structure proceeded with the growth of the

Hideki Masuda; Fumio Hasegwa; Sachiko Ono

1997-01-01

375

VAPOR PRESSURE AND MELTING BEHAVIOR OF SULFURIC ACID-WATER SYSTEMS  

EPA Science Inventory

An experimental apparatus was designed and constructed to use high vacuum and mass spectrometric techniques to determine total and partial vapor pressures above bulk liquid samples in the temperature range between -65C and 25C. Observations on the sulfuric acid-water system revea...

376

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

EPA Science Inventory

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

377

Mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid  

SciTech Connect

The authors attempted here to examine the mechanism of alkylation of isobutane by olefins in the presence of sulfuric acid in terms of an initial stage of activation of isoparaffin. The version of formation of tert-alkyl cations and the role of the catalyst in this stage were analyzed. 10 refs., 1 fig., 1 tab.

Baiburskii, V.L.; Khadzhiev, S.N.; Ovsyannikov, V.P.

1992-05-10

378

Effects of Sulfuric Acid Rain on Two Model Hardwood Forests: Throughfall, Litter Leachate, and Soil Solution.  

National Technical Information Service (NTIS)

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

J. J. Lee D. E. Weber

1980-01-01

379

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...

380

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

PubMed

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. PMID:18755541

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

2009-04-30

381

Catalytic process for removing SO from sulfuric acid plant off gases  

Microsoft Academic Search

The invention is directed to an integrated process for reducing the SO content of sulfuric acid plant off gases by (1) passing the SO-containing feed gas to the process over a specially defined multistage oxidation catalyst to convert SO to SO, (2) absorbing the SO in water to form HSO and (3) scrubbing the off gases with aqueous hydrogen peroxide

1976-01-01

382

Laboratory Investigation of Sulfurous Acid Leaching of Kaolin for Preparing Alumina.  

National Technical Information Service (NTIS)

In an attempt to develop technology to use domestic resources in place of imported bauxite, the Bureau of Mines investigated sulfurous acid leaching to extract alumina from kaolin. The process consists of leaching the calcined kaolin with a 30 wt-pct SO2 ...

A. E. Raddatz J. M. Gomes M. M. Wong

1981-01-01

383

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

Microsoft Academic Search

A framework for applying rates of heterogeneous chemical reactions measured in the laboratory to small sulfuric acid aerosols found in the stratosphere is presented. The procedure for calculating the applicable reactive uptake coefficients using laboratory-measured parameters is developed, the necessary laboratory-measured quantities are discussed, and a set of equations for use in models are presented. This approach is demonstrated to

David R. Hanson; A. R. Ravishankara; Susan Solomon

1994-01-01

384

Relationships between extinction, absorption, backscattering, and mass content of sulfuric acid aerosols  

Microsoft Academic Search

Linear relationships between aerosol extinction, absorption, backscatter, and mass content are derived for polydispersions of sulfuric acid aerosols. These relationships are independent of the form of the size distribution and are a consequence of approximating the corresponding Mie efficiency factors (the extinction efficiency Q\\/sub e\\/, the absorption efficiency Q\\/sub a\\/, and the backscatter gain G) by linear functions of the

R. G. Pinnick; S. G. Jennings; P. Chylek

1980-01-01

385

Optimum Ratio to Lysine of Threonine, Tryptophan, and Sulfur Amino Acids for Finishing Swine  

Microsoft Academic Search

Forty-eight crossbred (PIC line 26 x periods were designed to be slightly deficient in lysine Camborough 15) pigs were used in two finishing trials and to contain digestible Thr (65%), Trp (18%), and to compare the ideal ratios of threonine (Thr), SAA ( 60% 1 at the ideal ratio to digestible Lys tryptophan (Trp 1, and sulfur amino acids (SAA)

Joseph D. Hahn; David H. Bake

2010-01-01

386

Trace element transformations and partitioning during the roasting of pyrite ores in the sulfuric acid industry  

Microsoft Academic Search

Total concentrations combined with chemical partitioning of trace elements (Cd, Co, Cr, Mn, Ni, Pb, Tl, and Zn) in raw pyrite ore and solid roasting wastes were investigated in order to elucidate their transformations and partitioning during the roasting of raw pyrite ores in sulfuric acid production. In order to better understand the behavior of these elements during roasting, mineral

Chunxia Yang; Yongheng Chen; Pingan Peng; Chao Li; Xiangyang Chang; Yingjuan Wu

2009-01-01

387

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

Microsoft Academic Search

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

A. Seidel; Y. Zimmels

1998-01-01

388

Purification of regenerated sulfuric acid from crude-benzole-fraction washing  

Microsoft Academic Search

At the present stage of development in chemical technology, any newly developed and operated process must not only have high technical and economic performance indices but also ensure that no toxic wastes are produced to pollute the environment. From this point of view, the future of the sulfuric-acid process for refining aromatic hydrocarbons and naphthalene hinges on the problem of

V. V. Markov; M. N. Chernyavskaya; L. A. Korzhan

1976-01-01

389

How biogenic terpenes govern the correlation between sulfuric acid concentrations and new particle formation  

Microsoft Academic Search

New particle formation has been observed to take place all around the world. However, because of the inability to determine the chemical composition of the smallest clusters or particles, indirect tools such as the correlation between nucleation rate and measured sulfuric acid concentrations have been used to infer the nucleation mechanism. In this study we describe the observed correlation with

B. Bonn; M. Kulmala; I. Riipinen; S.-L. Sihto; T. M. Ruuskanen

2008-01-01

390

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

PubMed

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 ?2% (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. PMID:23618277

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

2013-06-01

391

A new approach to production rate measurement in sulfuric acid plants  

Microsoft Academic Search

Since the promulgation of the new source performance standards (NSPS) methods and standards in the December 23, 1971 Federal Register, attention has been increasingly focused on accurate determination of the process parameters for assessing compliance. For utility boilers, the standard is in units of pounds of particulate per million Btu's of heat input; for sulfuric acid plants, the units are

D. J. Grove; W. S. Smith

1983-01-01

392

Operating experience with unit for sulfuric acid alkylation of isobutane by butylenes  

Microsoft Academic Search

Long-term studies of the operation of units for the sulfuric acid alkylation of isobutanes by butylenes at the Burgas Petrochemical Combine [i] have been performed over a broad range of process conditions in order to define more precisely the technical capabilities of the unit and individual sections of the unit, and also to develop an improved unit and reconstruct existing

I. T. Tagavov; V. T. Sumanov; S. N. Khadzhiev

1988-01-01

393

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

EPA Science Inventory

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

394

The role of cluster energy nonaccommodation in atmospheric sulfuric acid nucleation  

SciTech Connect

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.

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

2010-01-11

395

Hydrogen production via sulfur-based thermochemical cycles: Part 2: Performance evaluation of Fe 2O 3-based catalysts for the sulfuric acid decomposition step  

Microsoft Academic Search

The sulfuric acid dissociation reaction, via which the production of SO2 and O2 is achieved, is the most energy intensive step of the so-called sulfur-based thermochemical cycles for the production of hydrogen. Efforts are focused on the feasibility and effectiveness of performing this reaction with the aid of a high-temperature energy\\/heat source like the sun. Such coupling can be achieved

Alberto Giaconia; Salvatore Sau; Claudio Felici; Pietro Tarquini; George Karagiannakis; Chrysoula Pagkoura; Christos Agrafiotis; Athanasios G. Konstandopoulos; Dennis Thomey; Lamark de Oliveira; Martin Roeb; Christian Sattler

2011-01-01

396

Surface modification of Mg 2Ni alloy in an acid solution of copper sulfate and sulfuric acid  

Microsoft Academic Search

A simple method of electroless copper plating for the surface modification of Mg2Ni alloy has been described in this paper. The plating solution contains only copper sulfate and sulfuric acid which are less toxic to the environment than the chemical reagents used in conventional copper plating solutions. Moreover, the coating process was very easy and fast to operate needing no

C. Y Wang; P Yao; D. H Bradhurst; H. K Liu; S. X Dou

1999-01-01

397

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

SciTech Connect

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). The effect of operation at higher anolyte concentrations on the flowsheet, and on the net thermal efficiency for a nuclear-heated HyS process, is examined and quantified.

Gorensek, M.; Summers, W.

2010-03-24

398

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

SciTech Connect

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

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

1991-07-01

399

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

SciTech Connect

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

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

1991-07-01

400

Kinetics of sulfuric acid leaching of low-grade zinc silicate ore  

Microsoft Academic Search

The results of a leaching kinetics study of low-grade zinc silicate ore with sulfuric acid are presented. Effect of ore particle size, reaction temperature, and acid concentration on zinc dissolution rate were determined. The results obtained show that leaching of about 94% of zinc is achieved using ?200+270 mesh ore particle size at a reaction temperature of 70C for 180

E. A Abdel-Aal

2000-01-01

401

Statistical modeling of sulfuric acid leaching of TiO 2 from red mud  

Microsoft Academic Search

The recovery with sulfuric acid leaching of Ti content of red mud, a waste of Turkey Etibank Seydi?ehir Aluminium Plants, has been studied by statistically designed experiments. The effects of relevant factors, such as temperature, leaching time, acid normality, solid-to-liquid ratio, stirring rate, on leaching yield of TiO2 have been investigated. Experiments have been planned by factorial design and orthogonal

Enes ?ayan; Mahmut Bayramo?lu

2000-01-01

402

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

403

Novel sulfur and selenium containing bis-?-amino acids from 4-hydroxyproline  

Microsoft Academic Search

The synthesis of new substituted prolines carrying at C-4 a second ?-amino acid residue is reported. The amino acid, l-cysteine or l-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared\\u000a with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications.\\u000a The introduction

Romualdo Caputo; Marina DellaGreca; Ivan de Paola; Domenico Mastroianni; Luigi Longobardo

2010-01-01

404

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

NASA Astrophysics Data System (ADS)

The hygroscopic properties of submicron soot particles during internal mixing with gaseous sulfuric acid have been investigated using a combined tandem differential mobility analyzer (TDMA) and differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) technique. Fresh particles exhibit no change in mobility size and mass at subsaturated conditions, whereas particles exposed to gaseous sulfuric acid (109-1010 molecule cm-3, 12 s contact time) experience significant mobility size and mass changes with increasing relative humidity (RH). The DMA-APM measurements reveal that particles of all sizes exposed to H2SO4 vapor gain mass with increasing RH because of absorption of water by sulfuric acid coating. However, on the basis of mobility size measurements using TDMA, upon humidification H2SO4-coated soot agglomerates display distinct hygroscopic growth patterns depending on their initial size and the mass fraction of condensed sulfuric acid. While small particles experience an increase in their mobility sizes, larger particles exhibit a marked shrinkage due to compaction. We suggest that determination of the hygroscopic properties of soot particles using a TDMA alone can be inconclusive. Restructuring of the soot agglomerates and filling of the voids that accompany the condensation of water-soluble materials and subsequent water absorption lead to little or no observable changes in particle mobility size at subsaturated RH even for particles that contain aqueous coatings. Extrapolation of our experimental results to the urban atmosphere indicates that initially hydrophobic soot particles acquire sufficient sulfate coating to become efficient CCN (cloud condensation nuclei) within a time period ranging from a few hours to a few days, dependent on the ambient H2SO4 level. The results imply that internal mixing with sulfuric acid through H2SO4 vapor condensation likely represents a common aging process for a variety of atmospheric aerosols. The variations in the size and hygroscopicity of soot particles during atmospheric processing influence their optical properties, cloud-forming potential, and human health effects.

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

2009-03-01

405

Reactivity of a condensedtype lignin model compound in the Mannich reaction and preparation of cationic surfactant from sulfuric acid lignin  

Microsoft Academic Search

The chemical conversion of phenolized sulfuric acid lignin (P-SAL), prepared from sulfuric acid lignin (SAL) by phenolation\\u000a with sulfuric acid catalyst, to novel cationic surfactant was investigated. To elucidate the chemical reactivity of the P-SAL\\u000a to a Mannich reaction, 1-guaiacyl-1-p-hydroxyphenylethane (I) as a simple phenolized sulfuric acid lignin model compound was reacted with dimethylamine and formaldehyde. Quantitative\\u000a analysis of the

Yasuyuki Matsushita; Seiichi Yasuda

2003-01-01

406

Sulphur Speciation and Turnover in Soils: Evidence from Sulfur K-Edge XANES Spectroscopy and Isotope Dilution Studies  

SciTech Connect

Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to quantify S species in humic substance extracts from ten soils from the UK, China and New Zealand, which differ in land use and agricultural management. XANES spectroscopy showed the presence of most reduced (sulphides, disulphides, thiols and thiophenes), intermediate (sulphoxides and sulphonates) and highly oxidised S (ester sulphates) forms, with the three groups representing 14-32%, 33-50% and 22-53% of the organic S in the humic substance extracts, respectively. Land use had a profound influence on the relative proportions of S species. Well-drained arable soils generally had a higher proportion of organic S present in the most oxidised form than the grassland soils collected nearby, whereas paddy soils showed a more reduced profile due to episodic flooding. In the Broadbalk Classical Experiment at Rothamsted, reversion of an arable system to grassland or woodland in the 1880s resulted in an increase of the most reduced and intermediate S species at the expense of the most oxidised S species. Long-term applications of farmyard manure to an arable plot also shifted S species from the most oxidised to the intermediate and the most reduced species. Sulphur immobilisation and gross mineralisation were determined in seven soils using the {sup 35}S isotope dilution method. Gross mineralisation during a 53-day incubation correlated more closely with the amounts of the most reduced and intermediate S species than with the most oxidised S species, suggesting that the former (C-bonded S) were the main source of organic S for mineralisation in the short-term.

Zhao,F.; Lehmann, J.; Solomon, D.; Fox, M.; McGrath, S.

2006-01-01

407

New sulfurated derivatives of valproic acid with enhanced histone deacetylase inhibitory activity.  

PubMed

One dithiolthione and two new methanethiosulfonate derivatives of valproic acid (VPA) were synthesized and tested in vitro as histone deacetylase (HDAC) inhibitors. The new molecules, as well as their sulfurated moieties, exhibited a much stronger inhibition of HDAC enzymatic and antiproliferative activities and histone hyperacetylation than VPA. ACS 2 is the most interesting compound among the new VPA derivatives and its sulfurated moiety, 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione, also known to be a metabolite of anethole trithione, seems to contribute significantly to its activity. This is the first time that HDAC inhibitory activity is described for dithiolethiones and thiosulfonates. PMID:18294844

Perrino, Elena; Cappelletti, Graziella; Tazzari, Valerio; Giavini, Erminio; Del Soldato, Piero; Sparatore, Anna

2008-03-15

408

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

SciTech Connect

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.

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

2012-01-01

409

Production of levulinic acid from wood raw material in the presence of sulfuric acid and its salts  

Microsoft Academic Search

The catalytic activities of sulfuric acid and of cobalt(II), iron(III), and aluminum sulfates in the thermal splitting of the cellulose and wood of various species in the presence of superheated steam at 250350C under flow conditions and at 150250C under autoclave conditions have been studied. The yield of levulinic acid from cellulose reaches 35 wt-% and from wood 16.018.0 wt-%.

A. A. Efremov; G. G. Pervyshina; B. N. Kuznetsov

1998-01-01

410

[Health aspects of sodium salts of sulfurous and sulfuric acids as environmental pollutants].  

PubMed

For the first time hygienic characteristics of long-term inhalation exposure effects of sodium salts of sulphurous and sulphuric acids in low concentrations on animals is given. The most sensitive organs and organism systems have been identified. MACs of the substances under study for the ambient air are proposed. The degree of contamination and the distance of spreading of sodium sulfate from the source have been determined in field studies. The size of the sanitary-protective zone has been substantiated. PMID:2292393

Denisov, Iu N; Tkachev, P G

1990-09-01

411

Ionic mechanisms for heterogeneous stratospheric reactions and ultraviolet photoabsorption cross sections for NO2+, HNO3, AND NO3? in sulfuric acid  

Microsoft Academic Search

We present room temperature photo-absorption cross sections between 180 and 340 nm for potassium nitrate dissolved in sulfuric acid-water solutions of 0, 80, and 96% sulfuric acid by mass. Other investigators have obtained ultraviolet absorption spectra for similar solutions above 220 nm, and there is a large literature on the spectra, species, and nitration reactions in sulfuric acid solutions. The

Joel D. Burley; H. S. Johnston

1992-01-01

412

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

PubMed

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

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

2011-04-01

413

Structural characterization and comparison of switchgrass ball-milled lignin before and after dilute acid pretreatment.  

PubMed

To reduce the recalcitrance and enhance enzymatic activity, dilute H(2)SO(4) pretreatment was carried out on Alamo switchgrass (Panicum virgatum). Ball-milled lignin was isolated from switchgrass before and after pretreatment. Its structure was characterized by (13)C, HSQC, and (31)P NMR spectroscopy. It was confirmed that ball-milled switchgrass lignin is of HGS type with a considerable amount of p-coumarate and felurate esters of lignin. The major ball-milled lignin interunit was the beta-O-4 linkage, and a minor amount of phenylcoumarin, resinol, and spirodienone units were also present. As a result of the acid pretreatment, there was 36% decrease of beta-O-4 linkage observed. In addition to these changes, the S/G ratio decreases from 0.80 to 0.53. PMID:19701727

Samuel, Reichel; Pu, Yunqiao; Raman, Babu; Ragauskas, Arthur J

2010-09-01

414

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

PubMed

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

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

2014-01-01

415

Biocatalysis research activity - generation of chemical intermediates by catalytic oxidative decarboxylation of dilute organic acids. ECUT: Energy Conversion and Utilization Technologies Program  

Microsoft Academic Search

Dilute streams of organic acids are byproducts of fermentation processes, paper and pulp industry waste streams, and processed urban waste. Currently, these are dumped since no method exists to extract the acids unless the streams are first concentrated. A catalytic process which would convert these dilute acids to useful chemicals such as alcohols and hydrocarbons would allow their utilization as

S. Di Stefano; A. Gupta; J. D. Ingham

1983-01-01

416

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

Microsoft Academic Search

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.

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

2004-01-01

417

Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.  

PubMed

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. PMID:23883276

Chen, Haihan; Grassian, Vicki H

2013-09-17

418

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

SciTech Connect

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.

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

1986-06-01

419

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

PubMed Central

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.

2012-01-01

420

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

421

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

NASA Astrophysics Data System (ADS)

We measured the first-order loss rate coefficients for CF2O on solid surfaces, ice and HNO3-treated ice, and on sulfuric acid solutions that coated the inside wall of a flow tube. We determined an upper limit for the uptake coefficient, ?, of 310-6 for CF2O on ice and HNO3-treated ice. A value for ? on a 60% (by weight) sulfuric acid solution of 3(+2/-3) 10-6 was measured and we observed a higher value over 40% acid, ? = 610-5 ( 30%). The loss of CF2O on stratospheric particles is a very slow process and will be insignificant for events that occur on timescales of a year, such as the annual polar chlorine activation phenomena.

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

1991-09-01

422

[A study of diluted aqueous solutions of humic acids by scanning microcalorimetry].  

PubMed

It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged, probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of diluted aqueous solutions of humic acids at approximately 58 degrees C has been found by differential scanning microcalorimetry, which indicates an increase in the hydration of hydrophobic groups. A jumpwise increase in heat capacity in the temperature range from 86 to 90 degrees C was also found, which is due likely to the hydration of hydrophobic groups in the interior of "micelles", due to the "devitrification" of the hydrophobic nucleus of micelle-like structures. It was shown that increasing the duration of vermicomposting leads to an increase in the relative content of the hydrophobic fraction of humic acids and in the cooperativity of the thermodynamic transition, which manifests itself in a jump of heat capacity, which probably results from the increase in the "micelle" size. PMID:21442885

Danilenko, A N; Braudo, E E; Pavlovskaia, N E; Iushkova, E I; Zhuravleva, I L

2011-01-01

423

Separation of hafnium from zirconium in sulfuric acid solutions using pressurized ion exchange  

SciTech Connect

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.

Hurst, F.J.

1981-01-01

424

Kinetics of the oxidation of hydrocarbon mixtures in the decomposition of spent sulfuric acid in a fluidized bed  

Microsoft Academic Search

In the production of methyl benzenesulfonate a waste product is spent sulfuric acid containing 70% monohydrate and about 10% benzenesulfonic acid, direct use of which is very difficult. The possibility was investigated of thermal contact decomposition of sulfuric acid wastes from the production of methyl benzenesulfonate in a fluidized bed at 700-800°C. In the first stage of the study, this

A. G. Khludenev; B. E. Shenfeld; B. T. Vasilev; A. F. Lozhkin

1983-01-01

425

Kinetics of gypsum formation and growth during the dissolution of colemanite in sulfuric acid  

NASA Astrophysics Data System (ADS)

One of the most important boron minerals, colemanite, is dissolved in aqueous sulfuric acid to produce boric acid whereby gypsum is formed as byproduct. Filtration of gypsum has an important role in boric acid production because gypsum affects the efficiency, purity and crystallization of boric acid. The formation and growth kinetics of gypsum during the dissolution of colemanite in aqueous sulfuric acid were studied in a batch reactor by varying the temperature (60-90C), stirring rate (150-400 rpm), and initial concentrations of the reactants. The initial CaO/H 2SO 4 molar ratio was varied between 0.21-0.85 by keeping the initial concentration of sulfate ion at [SO 42-] o=0.623 mol/l, and 0.85-3.41 by keeping the initial concentration of colemanite at [B 2O 3] o=0.777 mol/l. The crystallization of gypsum from the solution was followed by monitoring the calcium ion concentration in the solution as it is decreased by the formation of calcium sulfate precipitate. The calcium ion concentration in the liquid phase first undergoes a rapid exponential decay and then slowly approaches an asymptotic value of the saturation concentration at the respective temperature. The saturation concentration decreases with the increasing temperature from 5.2 mmol/l at 60C to 3.1 mmol/l at 80C, however, further increase in the temperature up to 90C causes an increase in the saturation concentration to 5.1 mmol/l. The stirring rate was found to have no significant effect on dissolution in the range of 150-400 rpm. The minimum saturation concentration of the calcium ion was obtained at 80C when the initial CaO/H 2SO 4 molar ratio is 0.85. The boric acid concentration in the solution decreases with the decreasing initial concentration of sulfuric acid. After the fast dissolution reaction of colemanite in aqueous sulfuric acid, the nucleation of the gypsum crystals first occurs from the supersaturated solution and then the crystals grow on these nuclei. The needle like crystals become wider and taller on prolong crystallization. The rate of gypsum crystallization reaction was second order with respect to saturation level. The evaluation of the kinetic data in an Arhenius plot gives an activation energy of 342 kJ/mol for the crystal growth of gypsum from the supersaturated solution obtained by dissolution of colemanite in aqueous sulfuric acid.

etin, E.; Ero?lu, ?.; zkar, S.

2001-11-01

426

Effects of simulated sulfuric acid rain on crop plants  

Microsoft Academic Search

Since relatively little is known about the effects of acid precipitation on growth and productivity of crop plants, a crop survey was initiated to study effects of HSO rain simulants on growth, yield, and quality of selected crops which were chosen to represent diverse taxonomic groups and crop products. Plants were grown in pots in field-exposure chambers and subjected to

C. J. Cohen; L. C. Grothaus; S. C. Perrigan

1981-01-01

427

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)

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.

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

428

Measurement of aerosol sulfuric acid: 1. Experimental setup, characterization, and calibration of a novel mass spectrometric system  

NASA Astrophysics Data System (ADS)

An instrument for the direct in situ measurement of aerosol sulfuric acid in the atmosphere has been developed, characterized and calibrated. The instrument termed Volatile Aerosol Component Analyzer (VACA) utilizes chemical ionization mass spectrometry technique for the detection of sulfuric acid. Prior to the mass spectrometric identification the sample flow is heated, and sulfuric acid is evaporated from the aerosol. The VACA system is characterized as a function of temperature, residence time in the flow reactor, aerosol size, and chemical composition. A unit consisting of an aerosol generator, a differential mobility analyzer, a hygrometer, and a condensation nuclei counter is used to calibrate the VACA instrument.

Curtius, J.; Arnold, F.

2001-12-01

429

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (Chlorophyta).  

PubMed

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva latuca was selected from the "Marine Park" in Tokyo Bay, and its growth rate (g-dry/[m2.d]) was measured using model reactors located on the land or on the surface of the sea at Yokohama. The growth rate of U. lactuca was recorded to be approx 20 g-dry/(m2.d), which is estimated to be 10 times greater than that in a natural field in the Marine Park. In addition, this growth rate was higher than that of conventional crops such as corn and rice on a farm or paddy. These data led us to newly design and propose a floating type of labor-efficient U. lactuca production system. d-Cysteinolic acid, which is included in U. lactuca as a major sulfur amino acid, inhibited the Fenton reaction, resulting in suppression of hydroxyl radical production and singlet oxygen. Addition of the sulfur amino acid (1 microM) to HepG2 cells markedly decreased the intracellular triglyceride level. Hence, this proposed facility also has the potential for industrial production of a valuable resource for the primary prevention of lifestyle-related diseases using enriched or eutrophied seawater. PMID:14981285

Hirayama, Shin; Miyasaka, Masashi; Amano, Hideomi; Kumagai, Yoshito; Shimojo, Nobuhiro; Yanagita, Teruyoshi; Okami, Yoshiro

2004-02-01

430

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

SciTech Connect

Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5? biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 2347% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ? 30 ?m before acidification to ? 60 ?m after acidification. These results demonstrated that E. coli DH5? biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: Effectiveness of E.coli DH5? biofilm to prevent MICD was studied. Conditions that lead to MICD were simulated by chemical acidification. Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. The presence of biofilm helped reduce the chemically-induced mortar deterioration. Biofilm remained alive and continued to grow during the acidification process.

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

2013-11-15

431

Corn stover saccharification with concentrated sulfuric acid: effects of saccharification conditions on sugar recovery and by-product generation.  

PubMed

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. PMID:22728786

Liu, Ze-Shen; Wu, Xiao-Lei; Kida, Kenji; Tang, Yue-Qin

2012-09-01

432

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

PubMed

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

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

2010-08-15

433

Mineralogical Controls on Microbial Diversity in a Sulfuric Acid Karst System  

NASA Astrophysics Data System (ADS)

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

Jones, A. A.; Bennett, P.

2011-12-01

434

Dilute-acid hydrolysis of cellulosic materials. III. Kinetics of a lignocellulose residue. Materials and processing technology  

Microsoft Academic Search

Kinetics of dilute-acid hydrolysis of lignocellulose residue from a furfural process is investigated experimentally. The rate constants are determined by a simplified method. By comparing with the kinetics of waste paper hydrolysis in similar conditions the residue is shown to be more easy to hydrolyze. This is evidently due to partial destruction of the crystalline structure of cellulose during the

V. J. Pohjola; M. Pulkkinen; P. Perttila

1977-01-01

435

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

436

Formation and growth of molecular clusters containing sulfuric Acid, water, ammonia, and dimethylamine.  

PubMed

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 pronounced at larger sizes, especially when the effect of water is considered. PMID:24963535

DePalma, Joseph W; Doren, Douglas J; Johnston, Murray V

2014-07-24

437

Effects of large (0.9 ?m) sulfuric acid aerosols on human pulmonary function  

Microsoft Academic Search

The effects of sulfuric acid particle concentration (mass\\/volume) and ambient temperatures on pulmonary function of young male nonsmokers were examined. Subjects (n = 11) thrice repeated a sequence of 20-min exercise (ventilation approximately 30 liters\\/min) and 20-min sitting rest. Pre- and postexposure pulmonary function tests (forced vital capacity maneuvers, lung volumes, maximum voluntary ventilation, R\\/sub aw\\/, TGV, and helium-oxygen FVC)

S. M. Horvath; L. J. Folinsbee; J. F. Bedi

1982-01-01

438

Raphia hookeri gum as a potential eco-friendly inhibitor for mild steel in sulfuric acid  

Microsoft Academic Search

Exudate gum from Raphia hookeri (RH) was tested as corrosion inhibitor for mild steel in H2SO4 using weight loss and hydrogen evolution techniques at 3060C. Results obtained revealed that RH act as corrosion inhibitor\\u000a for mild steel in sulfuric acid medium. The corrosion rates in all concentrations studied increased with rise in temperature.\\u000a The inhibition efficiency was observed to increase

S. A. Umoren; I. B. Obot; N. O. Obi-Egbedi

2009-01-01

439

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

Microsoft Academic Search

A series of novel regenerated cellulose (RC) films was prepared from cotton linters in 6wt% NaOH\\/4wt% urea aqueous solution by coagulating with 120wt% sulfuric acid (H2SO4) aqueous for 120min. Dependences of structure, morphology, light transmittance, mechanical properties, and water permeability of the films on the H2SO4 concentration and the coagulation time were investigated by using IR, UVVis, x-ray diffraction, scanning

Jinping Zhou; Lina Zhang; Hong Shu; Fangeng Chen

2002-01-01

440

New parameterization of sulfuric acid-ammonia-water ternary nucleation rates at tropospheric conditions  

Microsoft Academic Search

Recently, the classical theory of sulfuric acid-ammonia-water (H2SO4-NH3-H2O) nucleation was reinvestigated by including the effect of stable ammonium bisulfate formation into calculations. The predicted nucleation rates lowered by many orders of magnitude, bringing them close to agreement with the available experiments on H2SO4-NH3-H2O nucleation. However, because of complex thermodynamics involved, the theoretical calculations of nucleation rates are computationally demanding, and

J. Merikanto; I. Napari; H. Vehkamki; T. Anttila; M. Kulmala

2007-01-01

441

Parameterization of ammonia and water content of atmospheric droplets with fixed number of sulfuric acid molecules  

Microsoft Academic Search

We present a parameterization for numbers of water and ammonia molecules in an equilibrium droplet with fixed number of sulfuric acid molecules at known relative humidity, ammonia mixing ratio and temperature. The radius of the droplet is also parameterized. The parameterizations are based on macroscopic model of solution droplets and up-to-date thermodynamics. The binary parameterizations are valid for temperatures 190330K

I. Napari; R. Makkonen; M. Kulmala; H. Vehkamki

2006-01-01

442

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

Microsoft Academic Search

Printed circuit boards (PCBs) are essential components of electronic equipments which contain various metallic values. This\\u000a paper reports a hydrometallurgical recycling process for waste PCBs, which consists of the novel pretreatment consisting of\\u000a organic swelling of PCBs followed by sulfuric acid leaching of metals from waste PCBs. To recycle the waste PCBs, experiments\\u000a were carried out for the recovery of

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

2011-01-01

443

Sulfuric acid treatment of indium tin oxide for application of organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

In this paper, indium tin oxide (ITO) substrates were treated by ethanol, sulfuric acid (98%) and oxygen plasma respectively, based on which organic light-emitting diodes (OLEDs) with the same double-layer structure: ITO/N,N'-bis-(1-naphyl)-N,N'-diphenyl-1,1'- biphenyl-4,4'-diamine(NPB)/tris-(8-hydroxyquinoline) aluminum(Alq3)/ Mg:Ag/Al were fabricated. The morphology and compositions of differently treated ITO films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM results showed that all these treatments didn't change much the average roughness of ITO films, while ethanol has little influence on the large "peak-valley" (P-V) distance of ITO film; ITO film treated by sulfuric acid has suitable surface morphology with low P-V distance, low average roughness and small particle radius. XPS analysis proved that ethanol has the weakest ability to remove carbon contamination on the surface of ITO film which resulted in unevenly distributed current and high barriers for hole injection; sulfuric-acid-treated ITO film has the least contamination of carbon and higher concentration of oxygen vacancies, both of which are helpful for the improvement of devices. In the condition of room temperature and atmosphere and without encapsulation, measurements of the current-voltage, brightness-voltage and lifetime characteristics of these devices were conducted and showed good agreement with what expected from the results of AFM and XPS analysis: the ethanol-treated ITO provides very unstable performance with low efficiency for the device based on it, while the device based on sulfuric-acid-treated ITO anode had even better performance at higher driven voltage (>7V) comparing with the device based on oxygen-plasma-treated ITO substrate and had the highest current-luminance efficiency (3.2 cd/A) and the longest lifetime (2 hours).

Li, Wei-zhi; Ji, Xing-qiao; Zhong, Zhi-you; Wang, Tao; Jiang, Ya-dong

2006-01-01

444

Behaviour of southern red oak hemicelluloses and lignin in a mild sulfuric acid hydrolysis  

Microsoft Academic Search

Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w\\/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150 degrees C in 38 minutes and to extend the hydrolysis; 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded

A. V. Tran; R. P. Chambers

1986-01-01

445

Effects of sulfuric acid rain on two model hardwood forests: throughfall, litter leachate, and soil solution  

Microsoft Academic Search

Simulated sulfuric acid rain (pH 3.0, 3.5, 4.5, and 5.6) was applied to model forests containing either sugar maple (Acer saccharum) or red alder (Alnus rubra). Water samples were collected above and below the canopy, below the litter, and from 20 cm and 1 m below the surface of the soil. While throughfall chemistry was not very different from rain

J. J. Lee; D. E. Weber

1980-01-01

446

Pressure oxidation of pyrite in sulfuric acid media: a kinetic study  

Microsoft Academic Search

The oxidation kinetics of a massive pyrite (FeS2) sample from Zacatecas, Mexico were investigated in sulfuric acid solution under oxygen pressure. The effects of temperature (170230C), particle size (49125 ?m diameter), agitation speed (650950 rpm), oxygen partial pressure (3451035 kPa) and pulp density (120 g\\/L) were evaluated. The catalytic effect of Cu(II) was also observed.Fe(III) was found to be the

Hu Long; David G. Dixon

2004-01-01

447

Effect of KI on improving copper corrosion inhibition efficiency of benzotriazole in sulfuric acid electrolytes  

SciTech Connect

A synergistic effect exists when benzotriazole (BTAH) and iodide ions are used together to prevent the corrosion of copper in sulfuric acid. The nature of this effect has been studied systematically by using electrochemical techniques and X-ray photoelectron spectroscopy. The synergistic effect is due largely to the formation of a film of Cu(IBTA) complex and is probably polymeric in nature. This new complex film greatly depresses copper dissolution.

Wu, Y.C.; Zhang, P.; Pickering, H.W.; Allara, D.L. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering)

1993-10-01

448

Electrochemical laws of the cathodic reduction of a magnetite electrode in sulfuric and orthophosphoric acid solutions  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of magnetite in the solutions of sulfuric and orthophosphoric acids during cathodic polarization is studied. The theory of proton exchange is used for the interpretation of the experimental data on the influence of pH, the concentration of anions , and potential E on the cathodic reduction rate of magnetite. One of the postulates of the theory of proton exchange assumes the rate-determining step of protons for the cathodic reduction of metal oxide phases.

Kuzin, A. V.; Gorichev, I. G.; Batrakov, V. V.; Lainer, Yu. A.

2014-01-01

449

Carbohydrate analysis by a phenolsulfuric acid method in microplate format  

Microsoft Academic Search

Among many colorimetric methods for carbohydrate analysis, the phenolsulfuric acid method is the easiest and most reliable method. It has been used for measuring neutral sugars in oligosaccharides, proteoglycans, glycoproteins, and glycolipids. This method is used widely because of its sensitivity and simplicity. In its original form, it required 50450nmol of monosaccharides or equivalent for analysis and thus is inadequate

Tatsuya Masuko; Akio Minami; Norimasa Iwasaki; Tokifumi Majima; Shin-Ichiro Nishimura; Yuan C. Lee

2005-01-01

450

Increase in the stratospheric background sulfuric acid aerosol mass in the past 10 years  

Microsoft Academic Search

Data obtained from measurements of the stratospheric aerosol at Laramie, Wyoming (41°N), indicate that the background or nonvolcanic stratospheric sulfuric acid aerosol mass at northern mid-latitudes has increased by about 5 {plus minus} 2% per year during the past 10 years. Whether this increase is natural or anthropogenic could not be determined at this time because of inadequate information on

D. J. Hofmann

1990-01-01

451

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (chlorophyta)  

Microsoft Academic Search

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource\\u000a of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva lactuca was selected from the Marine Park in Tokyo Bay, and its growth rate (g-dry\\/[m2d]) was measured using model reactors located on

Shin Hirayama; Masashi Miyasaka; Hideomi Amano; Yoshito Kumagai; Nobuhiro Shimojo; Teruyoshi Yanagita; Yoshiro Okami

2004-01-01

452

Use of polymer coatings to protect plate-type heat exchangers in sulfuric acid production  

Microsoft Academic Search

The authors test anticorrosion coatings made of various thermoplastics, including Fluoroplastic 30P and Pentaplast A-2, for their protective properties when applied to steel-06KhN28MDT in the corrugated plates of heat exchangers used to cool sulfuric acid. They find the fluoroplastic to be superior not only in its corrosion resistance but also in its resistance to scale. The increase in thermal efficiency

Pavlenko