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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

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

E-print Network

Sugar yields from dilute sulfuric acid and sulfur dioxide pretreatments and subsequent enzymatic, Riverside, CA 92507, United States a r t i c l e i n f o Article history: Received 27 May 2011 Received%, and 10% wt.% of dry biomass were also tested at 180 °C for 10 min. Sugar yields were tracked

California at Riverside, University of

3

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 175°C and 1.25% (w/v) respectively. Following pretreatment the insoluble solids were separated by filtration and further submitted to enzymatic hydrolysis, while liquid fractions were analyzed for sugars and inhibitors. Response surface methodology was applied to analyze results based on the combined severity of pretreatment experiments. Optimized results show that up to 33 g of glucose and xylose per 100g raw material (65% of the glucose and xylose present in the raw material) may be available for fermentation after pretreatment at 167°C and 1.3% sulfuric acid concentration. PMID:23708847

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

2013-07-01

4

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 121°C, 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

5

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

6

The Effect of Flow Rate of Very Dilute Sulfuric Acid on Xylan, Lignin, and Total Mass Removal from Corn Stover  

E-print Network

, including physical (e.g., ball milling and grinding, high-energy radiation, steam explosion), chemical (acid, particularly using 0.7-3.0 wt % sulfuric acid, has proven to be very effective for realizing high hemicellulose with high yields.15 Fermentation inhibitors are also released or produced during dilute acid pretreatment

California at Riverside, University of

7

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 42.75°C, an aqueous ammonia concentration of 20.93%, and a reaction time of 48 h. The optimal enzyme concentration for saccharification was 30 filter paper units. The crystallinity index was approximately 60.23% and the Fourier transform infrared results showed the distinct peaks of glucan. Ethanol production using Saccharomyces cerevisiae K35 was performed to verify whether the glucose saccharified from rice straw was fermentable. Conclusions The combined pretreatment using dilute sulfuric acid and aqueous ammonia on rice straw efficiently yielded fermentable sugar and achieved almost the same crystallinity index as that of ?-cellulose. PMID:23898802

2013-01-01

8

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 112.5°C to 157.5°C, 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, João B; Giulietti, Marco; Silva, Silvio S; Felipe, Maria G A; Ferraz, André; Milagres, Adriane M F; Carvalho, Walter

2011-09-01

9

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

2010-02-01

10

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

11

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

12

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

13

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

14

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

NASA Astrophysics Data System (ADS)

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

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

15

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

16

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

17

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; Görgens, J F

2014-01-01

18

Sulfuric Acid on Europa  

NASA Technical Reports Server (NTRS)

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

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

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

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

1999-01-01

19

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

20

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

21

Sulfuric acid on Europa and the radiolytic sulfur cycle  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

22

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

23

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

24

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

PubMed

Ethanol production from poplar sawdust using sulfuric acid-assisted continuous twin screw-driven reactor (CTSR) pretreatment followed by simultaneous saccharification and fermentation (SSF) was investigated. Pretreatment with high acid concentration increased the cellulose content in the pretreated solid (74.9-76.9% in the range of 4.0-5.5wt.% H(2)SO(4)). The sugar content (XMG; xylan+mannan+galactan) in the treated-solid was 11.1-15.2% and 0.9-5.7% with 0.5wt.% and 7.0wt.%, respectively. The XMG recovery yield of the sample treated with 4.0wt.% H(2)SO(4) at 185°C was maximized at 88.6%. Enzymatic hydrolysis test showed a cellulose digestibility of 67.1%, 70.1%, and 73.6% with 15, 30, and 45FPU/g-cellulose, respectively. In the fed-batch SSF tests with initial enzyme addition, the ethanol yield of each stage almost reached a maximum at 28h, 48h, and 56h, respectively, with yields of 63.9% (16.5g/L), 78.4% (30.1g/L), and 81.7% (39.9g/L), respectively. PMID:23306134

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

2013-02-01

25

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 (H2SO4·H2O), and sulfuric acid tetrahydrate (H2SO4·4H2O) 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

26

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

E-print Network

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

California at Riverside, University of

27

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

E-print Network

of the temperature range investi- gated, 250 P to 680 F. 8~ A procedure was outlined for using data from the characteristic curves to esign a sulfur heat exchange system which will transfer heat at the same rate as an existing water heat exchange system... . 33 8-9A. Ratio of film conductance of diluted sulfur to that of water versus temperature. The flow of sulfur is considered lami- nar, and the flow of water is considered turbulent. Curve A is invalid for values of velocity times diameter above...

Stone, Porter Walwyn

2012-06-07

28

The generation of fermentation inhibitors during dilute acid hydrolysis of softwood  

Microsoft Academic Search

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

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

1999-01-01

29

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

30

Effects of dilute acid and steam explosion pretreatments on the cellulose structure and kinetics of cellulosic fraction hydrolysis by dilute acids in lignocellulosic materials  

Microsoft Academic Search

This article analyzes the effects of dilute sulfuric acid and steam explosion pretreatments on the fractionation and kinetics\\u000a of the dilute acid hydrolysis of the cellulosic fraction in different biomass substrates. A total of nine biomasses were analyzed:\\u000a three hardwoods, two soft-woods, and four types of herbaceous material. Sigmacell, a purified microcrystalline cellulosic\\u000a substrate, was also studied as a reference.

J. E. Carrasco; Ma C. Sáiz; A. Navarro; P. Soriano; F. Sáez; J. M. Martinez

1994-01-01

31

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, 160°C, and 0-5 min holding time. The conditions were chosen based on maximum glucose release after enzymatic hydrolysis, minimum loss of pentose sugars and minimum formation of sugar degradation products such as furfural and hydroxymethyl furfural. The pretreated corn stover after enzymatic saccharification generated 63.2 ± 2.2 and 63.7 ± 2.3 g total sugars per L at 0 and 5 min holding time, respectively. Furfural production was 0.45 ± 0.1 and 0.87 ± 0.4 g/L, respectively. The recombinant Escherichia coli strain FBR5 efficiently fermented non-detoxified corn stover hydrolyzate if the furfural content is <0.5 g/L. PMID:23747442

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

2013-08-01

32

Surface Pretreatment Based On Dilute Hexafluorozirconic Acid  

Microsoft Academic Search

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

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

33

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

34

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 115°C, and the Arrhenius activation energy was found to be 64.4

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

1987-01-01

35

21 CFR 582.1095 - Sulfuric acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01...2010-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.1095 Sulfuric acid. (a) Product....

2010-04-01

36

21 CFR 582.1095 - Sulfuric acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01...2012-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.1095 Sulfuric acid. (a) Product....

2012-04-01

37

21 CFR 582.1095 - Sulfuric acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01...2011-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.1095 Sulfuric acid. (a) Product....

2011-04-01

38

21 CFR 582.1095 - Sulfuric acid.  

21 Food and Drugs 6 2014-04-01...2014-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.1095 Sulfuric acid. (a) Product....

2014-04-01

39

21 CFR 582.1095 - Sulfuric acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01...2013-04-01 false Sulfuric acid. 582.1095 Section 582.1095 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...582.1095 Sulfuric acid. (a) Product....

2013-04-01

40

Sulfur Dioxide Crossover during the Production of Hydrogen and Sulfuric Acid in a PEM Electrolyzer  

E-print Network

Sulfur Dioxide Crossover during the Production of Hydrogen and Sulfuric Acid in a PEM Electrolyzer in the thermochemical conversion of sulfur dioxide to sulfuric acid for the large-scale production of hydrogen-17 In this thermochemical cycle, sulfuric acid is decomposed at high temperature 850°C to SO2 and wa- ter, and the SO2

Weidner, John W.

41

Interaction of sulfuric acid corrosion and mechanical wear of iron  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

42

Interaction of sulfuric acid corrosion and mechanical wear of iron  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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 ...

51

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

52

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

PubMed

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

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

2010-11-01

53

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 121°C. H2SO4 was the most effective acid in this experiment. We then analyzed the hydrolysis process in H2SO4 in detail using high performance liquid chromatography. At a sulfuric acid concentration of 1.8% and treatment time of 60 min, the yield of ethanol fermentable sugars (glucose and xylose) was high, (230.5 mg/g dry biomass, comprising 175.2 mg/g glucose and 55.3 mg/g xylose), with 48.6% of total reducing sugars being ethanol fermentable. Therefore, Enteromorpha could be a good candidate for production of fuel ethanol. In future work, the effects of temperature and biomass concentration on hydrolysis, and also the fermentation of the hydrolysates to ethanol fuel should be focused on.

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

2011-11-01

54

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 HâS (Claus plant feed), Claus plant tail gas, SOâ (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

55

SEMI-BATCH CRYSTALLIZATION OF GYPSUM FROM CALCITE AND SULFURIC ACID  

E-print Network

SEMI-BATCH CRYSTALLIZATION OF GYPSUM FROM CALCITE AND SULFURIC ACID F. Bard, D. Garcia , G. Févotte or reusing some compounds they contain in other production processes. The latter is of great interest, both- scale installation modeling the neutralization of a sulphuric acid solution by injection of a diluted

Paris-Sud XI, Université de

56

Friction and wear of nickel in sulfuric acid  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

57

Conversion of rice straw to sugars by dilute-acid hydrolysis  

Microsoft Academic Search

Hydrolysis of rice straw by dilute sulfuric acid at high temperature and pressure was investigated in one and two stages. The hydrolyses were carried out in a 10-l reactor, where the hydrolysis retention time (3–10min), pressure (10–35bar) and acid concentration (0–1%) were examined. Optimization of first stage hydrolysis is desirable to achieve the highest yield of the sugars from hemicellulose

Keikhosro Karimi; Shauker Kheradmandinia; Mohammad J. Taherzadeh

2006-01-01

58

Growth of nitric acid hydrates on thin sulfuric acid films  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

59

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

60

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

61

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

E-print Network

Comparison of microwaves to fluidized sand baths for heating tubular reactors for hydrothermal, and dilute sulfuric acid concentration combinations and hydrothermal pretreatment conditions. Microwave that microwave heating was more effective in altering cellulose structural features espe- cially in breakdown

California at Riverside, University of

62

High-Sulfur Coal and Acidic Water  

NSDL National Science Digital Library

In this video, a geologist measures the pH of water after high-sulfur coal from a Kentucky coal mine has been added to it. This test demonstrates that the sulfate salts found on the coal’s surface cause the water to become much more acidic.

Ket

2011-01-11

63

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

64

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

65

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...

66

Heterogeneous Interaction of Peroxyacetyl Nitrate on Liquid Sulfuric Acid  

NASA Technical Reports Server (NTRS)

The uptake of peroxyacetyl nitrate (PAN) on liquid sulfuric acid surfaces has been investigated using a fast-flow reactor coupled to a chemical ionization mass spectrometer. PAN was observed to be reversibly adsorbed on sulfuric acid.

Zhang, Renyi; Leu, Ming-Taun

1996-01-01

67

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

68

Characterization and fermentation of dilute-acid hydrolyzates from wood  

SciTech Connect

Dilute-acid hydrolyzates from alder, aspen, birch, willow, pine, and spruce were fermented without prior detoxification. The hydrolyzates were prepared by a one-stage hydrolysis process using sulfuric acid (5 g/L) at temperatures between 188 and 234 C and with a holding time of 7 min. The fermentations were carried out anaerobically by Saccharomyces cerevisiae (10 g of d.w./L) at a temperature of 30 C and an initial pH of 5.5. The fermentabilities were quite different for the different wood species, and only hydrolyzates of spruce produced at 188 and 198 C, hydrolyzates of pine produced at 188 C, and hydrolyzates of willow produced at 198 C could be completely fermented within 24 h. From the sum of the concentrations of the known inhibitors furfural and 5-(hydroxymethyl)furfural (HMF), a good prediction of the maximum ethanol production rate could be obtained, regardless of the origin of the hydrolyzate. Furthermore, in hydrolyzates that fermented well, furfural and HMF were found to be taken up and converted by the yeast, concomitant with the uptake of glucose.

Taherzadeh, M.J.; Niklasson, C.; Liden, G. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical Reaction Engineering] [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical Reaction Engineering; Eklund, R. [Mid Sweden Univ., Oernskoeldsvik (Sweden). Dept. of Industrial Technology] [Mid Sweden Univ., Oernskoeldsvik (Sweden). Dept. of Industrial Technology; Gustafsson, L. [Univ. of Goeteborg (Sweden). Dept. of General and Marine Microbiology] [Univ. of Goeteborg (Sweden). Dept. of General and Marine Microbiology

1997-11-01

69

Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions  

NASA Technical Reports Server (NTRS)

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

Leu, Ming-Taun

2006-01-01

70

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

71

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

SciTech Connect

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

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

1995-03-01

72

Two-stage dilute acid prehydrolysis of biomass  

DOEpatents

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

73

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

74

Chemical transformations of Populus trichocarpa during dilute acid pretreatment  

E-print Network

The structural complexity and unique chemical and physical properties of plant cell walls cause plant biomassChemical transformations of Populus trichocarpa during dilute acid pretreatment Shilin Cao and methoxyl group content and these changes were accompanied with an increase in condensed lignin. The dilute

California at Riverside, University of

75

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

76

Deposit Formation in the Evaporator of a Sulfuric Acid Recovery Plant for TiO2 Pigment Production  

Microsoft Academic Search

To produce high-quality white pigment, concentrated sulfuric acid is used to separate TiO2 from the raw material, which is usually an ore or a slag produced from titanium-rich iron ore. After dilution of the sulfuric acid in the crystallizer, it is re-concentrated in a multiple-effect evaporator set to a concentration of about 95%. The large variety of dissolved components in

H. Müller-Steinhagen; D. Lancefield

2007-01-01

77

FTIR studies of low temperature sulfuric acid aerosols  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

78

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

79

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

80

CHANGING THE ENVIRONMENT IN SWINE BUILDINGS USING SULFURIC ACID  

Microsoft Academic Search

Ammonia and dust concentrations in swine confinement buildings were reduced by spraying a mixture of water and sulfuric acid, by adding sulfuric acid to the swine manure, and by oxidizing the manure. The system was composed of a sprinkling system, spraying fluid at pH 5.5, and a sulfuric acid pump in the swine manure collection channel, ensuring that the pH

A. Ø. Jensen

81

Distribution of hydrate on Europa: Further evidence for sulfuric acid hydrate  

Microsoft Academic Search

Sulfuric acid hydrate has been proposed as an important species on Europa's surface, the acid being produced by radiolysis of surficial sulfur compounds. We investigated the spectral properties of disordered and crystalline forms of sulfuric acid and suggest that the hydration properties of Europa's hypothesized sulfuric acid lie between two end members: liquid sulfuric acid and its higher crystalline hydrates.

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

2005-01-01

82

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

83

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

PubMed

The most recent method of fungal chitosan purification, i.e., two steps of dilute sulfuric acid treatment, pretreatment of cell wall at room temperature for phosphate removal and extraction of chitosan from the phosphate free cell wall at high temperature, significantly reduces the chitosan molecular weight. This study was aimed at improvement of this method. In the pretreatment step, to choose the best conditions, cell wall of Rhizopus oryzae, containing 9% phosphate, 10% glucosamine, and 21% N-acetyl glucosamine, was treated with sulfuric, lactic, acetic, nitric, or hydrochloric acid, at room temperature. Sulfuric acid showed the best performance in phosphate removal (90%) and cell wall recovery (89%). To avoid depolymerisation of chitosan, hot sulfuric acid extraction was replaced with lactic acid treatment at room temperature, and a pure fungal chitosan was obtained (0.12 g/g cell wall). Similar pretreatment and extraction processes were conducted on pure shrimp chitosan and resulted in a chitosan recovery of higher than 87% while the reduction of chitosan viscosity was less than 15%. Therefore, the sulfuric-lactic acid method purified the fungal chitosan without significant molecular weight manipulation. PMID:24211428

Naghdi, Mitra; Zamani, Akram; Karimi, Keikhosro

2014-02-01

84

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 ...

85

Sulfuric acid resistance of high-volume fly ash concrete  

Microsoft Academic Search

The effects of ASTM Class C fly ash incorporation on mechanical properties and sulfuric acid resistance of concrete has been investigated within the scope of this study. Cement was replaced with fly ash up to 70%. Test results indicate that sulfuric acid resistance of steam-cured concrete could be improved significantly by incorporation of fly ash. Under standard curing conditions, the

Serdar Ayd?n; Halit Yaz?c?; Hüseyin Yi?iter; Bülent Baradan

2007-01-01

86

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...

87

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

88

Gas dilution system results and application to acid rain utilities  

SciTech Connect

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

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

1997-12-31

89

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

90

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

PubMed

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

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

2011-05-01

91

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

92

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

93

Monomeric carbohydrates production from olive tree pruning biomass: modeling of dilute acid hydrolysis.  

PubMed

Statistical modeling and optimization of dilute sulfuric acid hydrolysis of olive tree pruning biomass has been performed using response surface methodology. Central composite rotatable design was applied to assess the effect of acid concentration, reaction time and temperature on efficiency and selectivity of hemicellulosic monomeric carbohydrates to d-xylose. Second-order polynomial model was fitted to experimental data to find the optimum reaction conditions by multiple regression analysis. The monomeric d-xylose recovery 85% (as predicted by the model) was achieved under optimized hydrolysis conditions (1.27% acid concentration, 96.5°C and 138 min), confirming the high validity of the developed model. The content of d-glucose (8.3%) and monosaccharide degradation products (0.1% furfural and 0.04% 5-hydroxymethylfurfural) provided a high quality subtract, ready for subsequent biochemical conversion to value-added products. PMID:24096282

Puentes, Juan G; Mateo, Soledad; Fonseca, Bruno G; Roberto, Inês C; Sánchez, Sebastián; Moya, Alberto J

2013-12-01

94

Influence of sulfuric acid impregnation on the carbonization of cellulose  

NASA Astrophysics Data System (ADS)

That cellulose, as source of carbon materials, has a low char yield in pyrolysis can present serious difficulties. In this study, we focused on the effect of using sulfuric acid as a dehydration agent and examined the pyrolytic behavior of cellulose impregnated with sulfuric acid by using thermogravimetry and scanning electron microscopy. The mass yield of carbon after an 800 °C treatment in nitrogen was increased by 2-5 times with the addition of small amounts of sulfuric acid. Sample shrinkage during carbonization was also significantly reduced. These effects are interpreted as being the result of facilitated extraction of water from cellulose accompanied by development of extended carbon networks.

Kang, Kyu-Young; Kim, Dae-Young

2012-05-01

95

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...

96

Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols  

E-print Network

Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols Ben Kravitz,1 Alan of Earth's climate to conduct geoengineering experiments involving stratospheric injection of sulfur result from geoengineering of approximately 0.05 mEq m-2 a-1 is enough to negatively impact most

Robock, Alan

97

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

98

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

99

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

NASA Astrophysics Data System (ADS)

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 of sulfate anion production for cyclo-octal sulfur grains in frozen water at temperatures, energies, and dose rates appropriate for Europa using energetic electrons. The measured rate is GMixture(SO42-)=fSulfur (r0/r)?G1 molecules (100 eV)-1, where fSulfur is the sulfur weight fraction, r is the grain radius, r0=50 ?m, ??1.9, and G1=0.4±0.1. Equilibrium column densities N are derived for Europa's surface and follow the ordering N(H2SO4) » N(S)>N(SO2)>N(H2S). The lifetime of a sulfur atom on Europa's surface for radiolysis to H2SO4 is ?(-S)=120(r/r0)? years. Rapid radiolytic processing hides the identity of the original source of the sulfurous material, but Iogenic plasma ion implantation and an acidic or salty ocean are candidate sources. Sulfate salts, if present, would be decomposed in <3800 years and be rapidly assimilated into the sulfur cycle.

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

2002-06-01

100

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

101

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

102

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

PubMed

In the present study, combined steam (140-180°C) and dilute-acid pre-hydrolysis (0.0-2.0%) were applied to industrial hemp (Cannabis sativa L.), as pretreatment for lignocellulosic bioethanol production. The influence of the pretreatment conditions and cultivation type on the hydrolysis and ethanol yields was also evaluated. Pretreatment with 1% sulfuric acid at 180°C resulted in the highest glucose yield (73-74%) and ethanol yield of 75-79% (0.38-0.40 g-ethanol/g-glucose). Taking into account the costs of biomass processing, from field to ethanol facility storage, the field-dried hemp pretreated at the optimal conditions showed positive economic results. The type of hemp cultivation (organic or conventional) did not influence significantly the effectiveness of the pretreatment as well as subsequent enzymatic hydrolysis and ethanol fermentation. PMID:24821202

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

2014-07-01

103

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

...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 §...

2014-07-01

104

PROJECTION OF 1985 MARKET POTENTIAL FOR FGD (FLUE GAS DESULFURIZATION) BYPRODUCT SULFUR AND SULFURIC ACID IN THE U.S  

EPA Science Inventory

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 indu...

105

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

PubMed

We investigate the molecular interactions between the semivolatile ?-pinene oxidation product pinic acid and sulfuric acid using computational methods. The stepwise Gibbs free energies of formation have been calculated utilizing the M06-2X functional, and the stability of the clusters is evaluated from the corresponding ?G values. The first two additions of sulfuric acid to pinic acid are found to be favorable with ?G values of -9.06 and -10.41 kcal/mol. Addition of a third sulfuric acid molecule is less favorable and leads to a structural rearrangement forming a bridged sulfuric acid-pinic acid cluster. The involvement of more than one pinic acid molecule in a single cluster is observed to lead to the formation of favorable (pinic acid)2(H2SO4) and (pinic acid)2(H2SO4)2 clusters. The identified most favorable growth paths starting from a single pinic acid molecule lead to closed structures without the further possibility for attachment of either sulfuric acid or pinic acid. This suggests that pinic acid cannot be a key species in the first steps in nucleation, but the favorable interactions between sulfuric acid and pinic acid imply that pinic acid can contribute to the subsequent growth of an existing nucleus by condensation. PMID:24988284

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

2014-09-11

106

Laboratory-Measured Sulfuric Acid and Water Homogeneous Nucleation Rates from the SO2 + OH Reaction  

Microsoft Academic Search

Sulfuric acid and water binary homogeneous nucleation is the most important atmospheric nucleation system, but the nucleation mechanisms are poorly understood. Here, we report laboratory-measured sulfuric acid and water binary homogeneous nucleation rates at the atmospheric pressure, 288 K and 10 - 55 % relative humidity. The SO2 + OH reaction was used to produce sulfuric acid vapor. Residual sulfuric

D. Benson; S. Lee

2007-01-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

108

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

109

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

110

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...

111

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

EPA Science Inventory

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

112

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

Microsoft Academic Search

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

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

2004-01-01

113

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

114

Alloy 20 centrifugal pumps corrosion-free with sulfuric acid  

Microsoft Academic Search

General Battery Corporation manufactures an extensive line of lead-acid batteries for trucks, automobiles, motorcycles, electric-powered vehicles and lighting systems in eight eastern, mid-western and west coast plants. The plant in Hamburg, PA, which produces the most diversified line of batteries, was storing 66° Baume sulfuric acid in tanks located 30' overhead. The concentrated acid flows by gravity to four cutting

R. Miller; D. L. Ormond

1986-01-01

115

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

SciTech Connect

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

Gary M. Blythe

2000-12-01

116

INDUSTRIAL PROCESS PROFILES FOR ENVIRONMENTAL USE: CHAPTER 23. SULFUR, SULFUR OXIDES AND SULFURIC ACID  

EPA Science Inventory

The catalog of Industrial Process Profiles for Environmental Use was developed as an aid in defining the environmental impacts of industrial activity in the United States. Entries for each industry are in consistent format and form separate chapters of the study. The sulfur indus...

117

Determination of vertical fluxes of sulfur dioxide and dimethyl sulfide in the remote marine atmosphere by eddy correlation and an airborne isotopic dilution atmospheric pressure ionization mass spectrometer  

Microsoft Academic Search

Vertical fluxes of dimethyl sulfide (DMS) and sulfur dioxide (SO 2) were determined by eddy correlation and an isotopic dilution atmospheric pressure ionization mass spectrometer (APIMS) on an aircraft platform. The sampling frequency of the isotopic dilution APIMS ranged from 1 Hz to 25 Hz for real-time measurements. Measurements were made near the surface in the marine boundary layer to

Glenn M. Mitchell

2001-01-01

118

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

119

Dilute acid pretreatment of rapeseed straw for fermentable sugar generation.  

PubMed

The influence of the main pretreatment variables on fermentable sugar generation from rapeseed straw is studied using an experimental design approach. Low and high levels for pretreatment temperature (140-200 °C), process time (0-20 min) and concentration of sulfuric acid (0.5-2% w/v) were selected according to previous results. Glucose and xylose composition, as well as sugar degradation, were monitored and adjusted to a quadratic model. Non-sugar components of the hydrolysates were also determined. Enzymatic hydrolysis yields were used for assessing pretreatment performance. Optimization based on the mathematical model show that total conversion of cellulose from pretreated solids can be achieved at pretreatment conditions of 200 °C for 27 min and 0.40% free acid concentration. If optimization criteria were based on maximization of hemicellulosic sugars recovery in the hydrolysate along with cellulose preservation in the pretreated solids, milder pretreatment conditions of 144 °C, 6 min and 2% free acid concentration should be used. PMID:20826085

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

2011-01-01

120

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...

121

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

122

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

123

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 ...

124

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

Code of Federal Regulations, 2013 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...

2013-07-01

125

Correction to "Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols"  

E-print Network

Correction to "Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols (2010), Correction to "Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols from stratospheric geoengineering with sulfate aerosols" (Journal of Geophysical Research, 114, D14109

Robock, Alan

126

Process for the reclamation of battery acid and fluid from expended lead-acid batteries  

Microsoft Academic Search

This patent describes a method for recycling contaminated sulfuric acid from lead acid batteries to reclaimed sulfuric acid fore reuse in the batteries by removing contaminating iron impurities. It comprises: diluting the contaminated sulfuric acid to a concentration between 150 and 230 grams per liter; filtering the sulfuric acid through a first filter means to remove solid impurities.

1990-01-01

127

Reactive uptake of organic compounds by liquid sulfuric acid.  

NASA Astrophysics Data System (ADS)

The uptake of several organic compounds by laboratory surrogates for tropospheric sulfuric acid particles were investigated by mass spectrometry and infrared reflection-absorption spectroscopy. Among the compounds studied were acetone [(CH_3)_2CO], 2,4-hexanedione [CH_3CO(CH_2)_2COCH_3, MBO], and 2-methyl-3-buten-2-ol [CH_2CHC(CH_3)_2OH]. Experiments were carried out on ultrathin sulfuric acid films (ca. 10-100 monolayer equivalents thick) as functions of organic partial pressure, temperature, and acid composition. Acetone uptake is irreversible for acids that contain >70 weight percent (wt. %) H_2SO4, with kinetics that are second-order in concentration of dissolved acetone. Hexanedione and MBO are irreversibly taken for all acid compositions investigated (60-96 wt. %), with first-order uptake kinetics. In all cases, the irreversible uptake is a consequence of sulfuric acid catalyzed reactions that lead to the formation of new C-C bonds. Implications of these results for heterogeneous tropospheric chemistry will be discussed.

Roberts, J.; Michelsen, R.

2003-04-01

128

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

129

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

E-print Network

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

Elrod, Matthew J.

130

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

131

The East Penn process for recycling sulfuric acid from lead-acid batteries  

SciTech Connect

Prior to March 1992, the only component of the lead-acid battery that was not recycled by East Penn Manufacturing Company was the sulfuric acid electrolyte. This acid was unusable in new batteries because the iron level was found to exceed new product specifications. The development of a liquid ion exchange process to remove the iron from the acid allows East Penn to currently recover over three million gallons of sulfuric acid annually. The process is based upon the use of an iron selective liquid ion exchange material or solvent to extract iron from the sulfuric acid electrolyte followed by regeneration of the solvent. Equilibrium and kinetic data for the extraction and regeneration steps were collected in order to scale up the process to commercial scale. An electrochemical process for the treatment of the acid used in the regeneration step was also developed which significantly reduces the volume of strip acid required in the process.

Leiby, R.; Bricker, M. [East Penn Manufacturing Co., Inc., Lyon Station, PA (United States); Spitz, R. [Spitz (R.), Holbrook, MA (United States)

1995-12-31

132

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

133

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

134

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

135

Metabolism of sulfur amino acids in Saccharomyces cerevisiae.  

PubMed Central

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

Thomas, D; Surdin-Kerjan, Y

1997-01-01

136

Sulfur dynamics in an impoundment receiving acid mine drainage  

SciTech Connect

To quantify the importance of bacterial sulfate reduction (SR) in an acidified system, a sulfate influx-efflux budget was constructed for Lake Anna, an impoundment receiving acid mine drainage. Forty eight percent of the entering sulfate was removed from the water column within the 2 km arm of the lake that receives the pollution. Directly measured SR equaled 200% of the sulfate removal calculated in the budget. Thus, sulfide oxidation must be an important process in these sediments. The calculated alkalinity generated by sulfate removal was more than twice that necessary to account for the observed pH increase in the impoundment. Inorganic sulfur concentrations in the sediments of the impacted arm of Lake Anna were significantly greater than those in unpolluted sections of the lake. Label experiments showed that FeS and elemental sulfur (S{degree}) were the major products of SR in the impacted sediments. Inorganic sulfur (FeS, S{degree}, and pyrite) made up to 60% to 100% of the total sediment sulfur concentration. Pyrite concentrations were high and decreased exponentially with distance from the AMD source, indicating that the pyrite is stream detrius. FeS and S{degree} concentrations were highest at a station 1 km away from the AMD inflow, indicating in situ formation. There was no evidence for the formation of organic sulfur species.

Herlihy, A.T.

1987-01-01

137

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

PubMed

The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent. PMID:12830883

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

2003-05-16

138

Process for the extended use of strip acid employed in the reclamation of battery acid fluid from expanded lead-acid batteries  

Microsoft Academic Search

This patent describes a method for recycling contaminated sulfuric acid from lead acid batteries to reclaimed sulfuric acid for reuse in the batteries by removing contaminating iron impurities. It includes diluting the contaminated sulfuric acid to a concentration between 150 and 230 grams per liter; filtering the sulfuric acid through a first filter means to remove solid impurities; oxidizing the

R. A. Spitz; M. Bricker

1991-01-01

139

Laboratory stress corrosion cracking studies with sulfur acids and chlorides  

SciTech Connect

Stress corrosion cracking (SCC) caused by polythionic acid and/or chlorides has occurred in coal liquefaction pilot plants. This problem is also common in refineries and has been extensively researched. This study examines: (1) the relationship of the ASTM standard ferric sulfate-sulfuric acid test for determining sensitization to resistance to polythionic SCC; (2) the cracking resistance of higher-alloy. Fe-Ni-Cr materials and common austenitic stainless steels (SS); and (3) the effect of chloride concentrations up to 1% in polythionic acid solutions on cracking behavior. The ferric sulfatesulfuric acid test can be used as an acceptance test for materials resistant to polythionic acid SCC. More highly alloyed materials were more resistant to sensitization than most austenitic SS and were virtually unattacked in polythionic acid solutions containing up to 1% chloride. Chloride increased the corrosion rate and caused localized pitting but it did not significantly affect the number of failures or the failure mode.

Baylor, V.B.

1985-10-01

140

Analysis of sulfur–iodine thermochemical cycle for solar hydrogen production. Part I: decomposition of sulfuric acid  

Microsoft Academic Search

The sulfur–iodine (S–I) thermochemical water splitting cycle is one of the most studied cycles for hydrogen (H2) production. S–I 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

141

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

142

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, 2001 through September 30, 2001. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric acid and hydrofluoric acid is also being determined, as is the removal of arsenic, a known poison for NO{sub x} selective catalytic reduction (SCR) catalysts. EPRI, the Tennessee Valley Authority (TVA), FirstEnergy Corporation, and the Dravo Lime Company are project co-funders. URS Corporation is the prime contractor. During the current period, American Electric Power (AEP) joined the project as an additional co-funder and as a provider of a host site for testing. This is the fourth reporting period for the subject Cooperative Agreement. During this period, two long-term sorbent injection tests were conducted, one on Unit 3 at FirstEnergy's Bruce Mansfield Plant (BMP) and one on Unit 1 at AEP's Gavin Station. These tests determined the effectiveness of injecting alkaline slurries into the upper furnace of the boiler as a means of controlling sulfuric acid emissions from these units. The alkaline slurries tested included commercially available magnesium hydroxide slurry (Gavin Station), and a byproduct magnesium hydroxide slurry (both Gavin Station and BMP). The tests showed that injecting either the commercial or the byproduct magnesium hydroxide slurry could achieve up to 70 to 75% sulfuric acid removal. At BMP, the overall removal was limited by the need to maintain acceptable electrostatic precipitator (ESP) particulate control performance. At Gavin Station, the overall sulfuric acid removal was limited because the furnace injected sorbent was less effective at removing SO{sub 3} formed across the SCR system installed on the unit for NO{sub x} control than at removing SO{sub 3} formed in the furnace. Balance of plant impacts, primarily on the ESP particulate control device, were also determined during both tests. These results are presented and discussed in this report.

Gary M. Blythe

2001-11-06

143

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

144

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

Microsoft Academic Search

Hydrocarbons, native sulfur, Mississippi Valley-type (MVT) deposits, and sulfuric acid karst in the Delaware Basin, southeastern New Mexico, and west Texas, USA, are all genetically related through a series of sulfur redox reactions. The relationship began with hydrocarbons in the basin that reacted with sulfate ions from evaporite rock to produce isotopically light (d34S = -22 to -12) H2S and

C. Hill

1995-01-01

145

EFFECTS OF SULFURIC ACID MIST EXPOSURE ON PULMONARY FUNCTION  

EPA Science Inventory

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

146

Resistance of different types of concrete mixtures to sulfuric acid  

Microsoft Academic Search

The resistance of seven different concrete mixtures against a 0.5% sulfuric acid solution was examined. The difference between\\u000a high sulfate resistant Portland cement and blast furnace cement, as well as the influence of polymer modifications of the\\u000a concrete and the addition of silica fume were issues of the investigation. All concrete mixtures were submitted to an alternating\\u000a immersion and drying

J. Monteny; N. De Belie; L. Taerwe

2003-01-01

147

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

148

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

149

Electrosynthesis of Poly(azure B) from Sulfuric Acid Solution  

Microsoft Academic Search

Electrochemical polymerization of azure B from sulfuric acid solution was carried out by using cyclic voltammetry. The electrolytic solution consisted of 5.0 mmol · dm azure B and 0.3 mol · dm H2SO4. The temperature for polymerization was controlled at 20°C. A blue film, i.e., poly(azure B) was formed on a platinum foil and had a electrochemical reversibility, stability and a fast charge transfer ability in

Chuanxiang Chen; Yuhua Gao

2007-01-01

150

Sulfuric Acid Intercalated Graphite Oxide for Graphene Preparation  

PubMed Central

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

Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

2013-01-01

151

Laryngeal cancer and occupational exposure to sulfuric acid  

SciTech Connect

Workers on an ethanol unit which used sulfuric acid in strong concentrations at a large refinery and chemical plant in Baton Rouge, Louisiana were reported in 1979, at excess risk for upper respiratory cancer. The carcinogen implicated by indirect evidence was diethyl sulfate. However, with the continued use of sulfuric acid in the same plant, and with additional cases not attributable to the ethanol process, the hypothesis of an association between sulfuric acid exposure and upper respiratory cancer was tested. Each of 50 confirmed cases of upper respiratory cancer diagnosed between 1944 and 1980, was matched to at least three controls on sex, race, age, date of initial employment, and duration of employment. Thrity-four of the 50 cases were laryngeal cancers. Data were obtained from existing plant records. Retrospective estimates of exposure were made without regard to case or control status. Findings from conditional logistic regression techniques were supported by other statistical methods. Among workers classified as potentially highly exposed, four-fold relative risks for all upper respiratory cancer sites combined were exceeded by the relative risk for laryngeal cancer specifically. Exposure-response and consistency across various comparisons after controlling statistically for tobacco-use, alcoholism and other previously implicated risk factors, suggest increased cancer risk with higher exposure.

Soskolne, C.L.; Zeighami, E.A.; Hanis, N.M.; Kupper, L.L.; Herrmann, N.; Amsel, J.; Mausner, J.S.; Stellman, J.M.

1984-09-01

152

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

Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

2013-01-01

153

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

Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

2013-12-01

154

Sulfuric Acid Speleogenesis: Microbial Karst and Microbial Crust  

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

155

Possible Roles of Sulfur-Containing Amino Acids in a Chemoautotrophic Bacterium-Mollusc Symbiosis  

E-print Network

Possible Roles of Sulfur-Containing Amino Acids in a Chemoautotrophic Bacterium-Mollusc Symbiosis avoiding its toxic effects. The sulfur-containing free amino acids taurine and thiotaurine may function in sulfide detoxification by serving as sulfur storage compounds or as transport compounds between symbiont

McFall-Ngai, Margaret

156

Effects of acid rain and sulfur dioxide on marble dissolution  

USGS Publications Warehouse

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

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

1994-01-01

157

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

158

Size-Resolved Sulfuric Acid Mist Concentrations At Phosphate Fertilizer Manufacturing Facilities In Florida  

Microsoft Academic Search

Strong inorganic acid mists containing sulfuric acid were identified as a 'known human carcinogen' in a National Toxicology Program (NTP) report where phosphate fertilizer manufacture was listed as one of many occupational exposures to strong acids. To properly assess the occupational exposure to sulfuric acid mists in modern facilities, approved National Institute for Occupational Safety and Health (NIOSH) Method 7903

YU-MEI HSU; CHANG-YU WU; DALE A LUNDGREN; BRIAN K BIRKY

2007-01-01

159

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

160

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

161

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

162

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

Gary M. Blythe; Richard McMillan

2002-02-04

163

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

Gary M. Blythe; Richard McMillan

2002-03-04

164

Distribution of hydrate on Europa: Further evidence for sulfuric acid hydrate  

NASA Astrophysics Data System (ADS)

Sulfuric acid hydrate has been proposed as an important species on Europa's surface, the acid being produced by radiolysis of surficial sulfur compounds. We investigated the spectral properties of disordered and crystalline forms of sulfuric acid and suggest that the hydration properties of Europa's hypothesized sulfuric acid lie between two end members: liquid sulfuric acid and its higher crystalline hydrates. The spectra of these end members are similar except for spectral shifts at the band edges. We measured the optical constants of sulfuric acid octahydrate and used these with simple radiative transfer calculations to fit Europa spectra obtained by Galileo's Near Infrared Mapping Spectrometer (NIMS). The global distribution of the hydrate that we associate here with hydrated sulfuric acid shows a strong trailing-side enhancement with a maximum fractional hydrate abundance of 90% by volume, corresponding to a sulfur atom to water molecule ratio of 10%. The hydrate concentration spatially correlates with the ultraviolet and visible absorption of the surface and with the sulfur dioxide concentration. The asymmetric global distribution is consistent with Iogenic plasma ion implantation as the source of the sulfur, possibly modified by electron irradiation and sputtering effects. The variegated distribution also correlates with geologic forms. A high spatial resolution image shows resolved lineae with less hydrate appearing within the lineae than in nearby crustal material. The low concentration of hydrated material in these lineae argues against their conveying sulfurous material to the surface from the putative ocean.

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

2005-10-01

165

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

PubMed Central

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

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

2013-01-01

166

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

PubMed

The effects of fuel sulfur content and primary dilution on PM number emissions were investigated during transient operations of an old and a modern diesel engine. Emissions were also studied during steady-state operations in order to confirm consistency with previous findings. Testing methods were concurrent with those implemented by the EPA to regulate PM mass emissions, including the use of the Federal Transient Testing Procedure-Heavy Duty cycle to simulate transient conditions and the use of a Critical Flow Venturi-Constant Volume System to provide primary dilution. Steady-state results were found to be consistent with previous studies in that nuclei-mode particulate emissions were largely reduced when lower-sulfur content fuel was used in the newer engine, while the nuclei-mode PM emissions from the older engine were much less affected by fuel sulfur content. The transient results, however, show that the total number of nuclei-mode PM emissions from both engines increases with fuel sulfur content, although this effect is only seen under the higher primary dilution ratios with the older engine. Transient results further show that higher primary dilution ratios increase total nuclei-mode PM number emissions in both engines. PMID:17948797

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

2007-09-15

167

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

168

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

SciTech Connect

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

F Xu; Y Shi; X Wu

2011-12-31

169

POTENTIAL ABATEMENT PRODUCTION AND MARKETING OF BYPRODUCT SULFURIC ACID IN THE U.S  

EPA Science Inventory

The report gives results of an evaluation of the market potential for sulfur and sulfuric acid byproducts of combustion in power plant boilers. (Air quality regulations require control of SOx emissions from power plant boilers. Recovery of sulfur in useful form would avoid waste ...

170

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

171

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

PubMed

The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent. PMID:12830881

Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi

2003-05-16

172

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID REMOVAL  

SciTech Connect

The objective of this project has been to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The project was co-funded by the U.S. DOE National Energy Technology Laboratory under Cooperative Agreement DE-FC26-99FT40718, along with EPRI, the American Electric Power Company (AEP), FirstEnergy Corporation, the Tennessee Valley Authority, and Carmeuse North America. Sulfuric acid controls are becoming of increased interest for coal-fired power generating units for a number of reasons. In particular, sulfuric acid can cause plant operation problems such as air heater plugging and fouling, back-end corrosion, and plume opacity. These issues will likely be exacerbated with the retrofit of selective catalytic reduction (SCR) for NOX control, as SCR catalysts are known to further oxidize a portion of the flue gas SO{sub 2} to SO{sub 3}. The project tested the effectiveness of furnace injection of four different magnesium-based or dolomitic alkaline sorbents on full-scale utility boilers. These reagents were tested during one- to two-week tests conducted on two FirstEnergy Bruce Mansfield Plant (BMP) units. One of the sorbents tested was a magnesium hydroxide slurry byproduct from a modified Thiosorbic{reg_sign} Lime wet flue gas desulfurization process. The other three sorbents are available commercially and include dolomite, pressure-hydrated dolomitic lime, and commercially available magnesium hydroxide. The dolomite reagent was injected as a dry powder through out-of-service burners. The other three reagents were injected as slurries through air-atomizing nozzles inserted through the front wall of the upper furnace. After completing the four one- to two-week tests, the most promising sorbents were selected for longer-term (approximately 25-day) full-scale tests on two different units. The longer-term tests were conducted to confirm sorbent effectiveness over extended operation on two different boilers, and to determine balance-of-plant impacts. The first long-term test was conducted on FirstEnergy's BMP Unit 3, and the second was conducted on AEP's Gavin Plant, Unit 1. The Gavin Plant test provided an opportunity to evaluate the effects of sorbent injected into the furnace on SO{sub 3} formed across an operating SCR reactor. A final task in the project was to compare projected costs for furnace injection of magnesium hydroxide slurries to estimated costs for other potential sulfuric acid control technologies. Estimates were developed for reagent and utility costs, and capital costs, for furnace injection of magnesium hydroxide slurries and seven other sulfuric acid control technologies. The estimates were based on retrofit application to a model coal-fired plant.

Gary M. Blythe

2004-01-01

173

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 81°C. 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. PMID:23335768

Druschel, Gregory K.

2013-01-01

174

Relative contributions of sulfuric and nitric acids in acid rain to the acidification of the ecosystem: implications for control strategies  

Microsoft Academic Search

Much of northeastern North America has been receiving precipitation of pH 4.6 or less, i.e. more than ten times more acid than normal rain (pH = 5.6) for at least the past 20 to 30 years. Originally, this acidity was almost totally due to sulfuric acid. These inputs of sulfuric acid in the very acid sensitive Adirondacks may have removed

R. A. N

1981-01-01

175

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

SciTech Connect

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

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

1988-03-01

176

A new test procedure for biogenic sulfuric acid corrosion of concrete  

PubMed

A new test method is described for biogenic sulfuric acid corrosion of concrete, more specifically in sewer conditions. The aim of the new test method is the development of an accelerated and reproducible procedure for monitoring the resistance of different types of concrete with regard to biogenic sulfuric acid corrosion. This experimental procedure reflects worst case conditions by providing besides H2S, also an enrichment of thiobacilli and biologically produced sulfur. By simulating the cyclic processes occurring in sewer pipes, significant differences between concrete mixtures could be detected after 51 days. Concrete modified by a styrene-acrylic ester polymer demonstrated a higher resistance against biogenic sulfuric acid attack. PMID:11068828

Vincke; Verstichel; Monteny; Verstraete

1999-01-01

177

Efficient Biginelli Reaction Catalyzed by Sulfamic Acid or Silica Sulfuric Acid under Solvent?Free Conditions  

Microsoft Academic Search

Sulfamic acid efficiently catalyzes the three?component condensation reaction of aldehydes, 1,3?dicarbonyl compounds, and urea\\/thiourea under solvent?free conditions to afford the corresponding dihydropyrimidinones and thio?derivatives in high yields. Silica sulfuric acid is also found to be an efficient catalyst for the Biginelli reaction under solvent?free conditions. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of

2007-01-01

178

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. Vegliò

2009-01-01

179

Electrochemical behaviour of lead electrode in sulfuric acid solution containing citric acid  

NASA Astrophysics Data System (ADS)

The electrochemical behaviour of a lead electrode as the positive electrode (in PbO 2 form) and the negative electrode of a lead/acid battery in sulfuric acid solution containing different concentrations of citric acid has been studied by cyclic voltammetry. For the behaviour of lead as a positive electrode, a new layer of PbO 2 is formed in the presence of citric acid. It is difficult for this layer to be reduced and, therefore, the conductivity between the positive grid and the positive active material will be greater than that in pure sulfuric acid solution. The peak currents attributed to the formation and reduction of PbO 2, and to the evolution of oxygen, increase with the concentration of citric acid. The limits of the effects are reached at about 2 g/1 citric acid in 4.5 M H 2SO 4. For the behaviour of lead as a negative electrode, the peak currents attributed to the oxidation of lead to PbSO 4 and to the evolution of hydrogen gas also increase with the concentration of citric acid. In 4.5 M H 2SO 4, the limits of these effects are reached at a citric acid concentration of 2 and 3 g/1, respectively. The observed behaviour is caused by the adsorption of citric acid on the PbO 2, lead and PbSO 4 surfaces.

Wei, Guo-Lin; Wang, Jia-Rong

180

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

181

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...

182

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

183

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...

184

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

185

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

186

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

187

ON-LINE OPTIMIZATION, ENERGY ANALYSIS AND ENVIRONMENTAL IMPACT ASSESSMENT OF SULFURIC ACID CATALYZED ALKYLATION  

E-print Network

ON-LINE OPTIMIZATION, ENERGY ANALYSIS AND ENVIRONMENTAL IMPACT ASSESSMENT OF SULFURIC ACID in sulfuric acid consumption potentially could be obtained. 1. Introduction Alkylation process is one pool, increased amounts of gasoline per volume of crude oil and high heats of combustion. The overall

Pike, Ralph W.

188

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...

189

[Gene mining of sulfur-containing amino acid metabolic enzymes in soybean].  

PubMed

The genes of sulfur-containing amino acid synthetases in soybean are essential for the synthesis of sulfur-containing amino acids. Gene mining of these enzymes is the basis for the molecular assistant breeding of high sulfur-containing amino acids in soybean. In this study, using software BioMercator2.1, 113 genes of sulfur-containing amino acid enzymes and 33 QTLs controlling the sulfur-containing amino acids content were mapped onto Consensus Map 4.0, which was integrated by genetic and physical maps of soybean. Sixteen candidate genes associated to the synthesis of sulfur-containing amino acids were screened based on the synteny between gene loci and QTLs, and the effect values of QTLs. Through a bioinformatic analysis of the copy number, SNP information, and expression profile of candidate genes, 12 related enzyme genes were identified and mapped on 8 linkage groups, such as D1a, M, A2, K, and G. The genes corresponding to QTL regions can explain 6%?38.5% genetic variation of sulfur-containing amino acids, and among them, the indirect effect values of 9 genes were more than 10%. These 12 genes were involved in sulfur-containing amino acid metabolism and were highly expressed in the cotyledons and flowers, showing an abundance of SNPs. These genes can be used as candidate genes for the development of functional markers, and it will lay a foundation for molecular design breeding in soybean. PMID:25252311

Qiu, Hongmei; Hao, Wenyuan; Gao, Shuqin; Ma, Xiaoping; Zheng, Yuhong; Meng, Fanfan; Fan, Xuhong; Wang, Yang; Wang, Yueqiang; Wang, Shuming

2014-09-01

190

Electrolytic nature of aqueous sulfuric acid. 1. Activity.  

PubMed

According to the literature, when H(2)SO(4) dissolves in water, (1) it retains its molecular formula and tetrahedral structure of two O atoms and two OH groups bonded to a central S atom, and (2) it ionizes partially, as a 1-1 electrolyte, to H(+) (H(3)O(+)) and HSO(4)(-); the latter ion further dissociates at low concentrations (<0.1 M) to H(+) and SO(4)(2-). Using the Debye-Hückel (DH) limiting law at very low concentration, and the smaller-ion shell (SiS) model of strong electrolyte solutions-an extension of the DH model for ion size dissimilarity-up to moderate concentration, I examine the theory-experiment fit of the mean ionic activity coefficient (?(±)) of the acid as a function of concentration (at 0 to ?6 m) and of temperature (at 0-60 °C). The fit is impossible if H(2)SO(4) in water is assumed to be a 1-1 or 1-2 electrolyte, but is excellent when the acid is treated instead as a strong 1-3 electrolyte; that is, aqueous sulfuric acid behaves as a fully dissociated H(3)A acid. At 25 °C, the SiS best fit is achieved with the H(+) diameter being 1.16 Å (as obtained for strong mineral 1-1 protonic acids) and with the A(3-) ionic diameter being 5.77 Å. On the basis of the present study, H(2)SO(4) in water may be H(4)SO(5) (dubbed "sulfoxuric", or parasulfuric acid) completely ionized to 3H(+) and the ("bisulfoxate", or parabisulfate) anion HSO(5)(3-). The calculated standard potential of a newly proposed half-cell reaction, H(2) + HSO(5)(3-) ? H(+) + SO(4)(2-) + H(2)O + 2e(-), at 25 °C, is -1.0933 V. PMID:22924586

Fraenkel, Dan

2012-09-27

191

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

SciTech Connect

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

Hill, C.A.

1995-02-01

192

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

193

Galvanic interactions between alloys and minerals in sulfuric acid  

SciTech Connect

Many semiconducting minerals have sufficient conductivity to permit electrochemical reactions on their surfaces. Consequently, galvanic interactions will occur when such minerals are coupled to metals or other conducting minerals. Accelerated galvanic corrosion of metals coupled to minerals is likely because most minerals exhibit potentials in solution that are noble to the corrosion potentials (E[sub corr]) of typical metal alloys. Anodic and cathodic polarization diagrams can be used to predict galvanic corrosion rates expected from any given galvanic couple in a particular corrosive electrolyte. Polarization diagrams were presented for numerous minerals and alloys in sulfuric acid (H[sub 2]SO[sub 4]). Examples demonstrated how the curves could be used to estimate the likelihood of galvanic corrosion and the reaction rates to be expected in metal-metal, metal-mineral, and mineral-mineral couples. The effects of relative cathode-to-anode surface area, application to initiation of pitting corrosion, and limitations of the method also were reviewed.

Jones, D.A. (Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering); Paul, A.J.P. (Concurrent Technologies Corp., Johnstown, PA (United States))

1994-07-01

194

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

PubMed

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

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

2012-06-30

195

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

196

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 81°C. The production of polysulfide is likely due to the abiotic reaction between S(8)(0) and the biologically produced H(2)S, as evinced by a rapid cessation of polysulfide formation when the growth temperature was decreased, inhibiting the biological production of sulfide. After an additional 5 days of growth, nanoparticulate S(8)(0) was detected in the cultivation medium, a result of the hydrolysis of polysulfides in acidic medium. To examine whether soluble polysulfides and/or nanoparticulate S(8)(0) can serve as terminal electron acceptors (TEA) supporting the growth of A. sulfurireducens, total sulfide concentration and cell density were monitored in batch cultures with S(8)(0) provided as a solid phase in the medium or with S(8)(0) sequestered in dialysis tubing. The rates of sulfide production in 7-day-old cultures with S(8)(0) sequestered in dialysis tubing with pore sizes of 12 to 14 kDa and 6 to 8 kDa were 55% and 22%, respectively, of that of cultures with S(8)(0) provided as a solid phase in the medium. These results indicate that the TEA existed in a range of particle sizes that affected its ability to diffuse through dialysis tubing of different pore sizes. Dynamic light scattering revealed that S(8)(0) particles generated through polysulfide rapidly grew in size, a rate which was influenced by the pH of the medium and the presence of organic carbon. Thus, S(8)(0) particles formed through abiological hydrolysis of polysulfide under acidic conditions appeared to serve as a growth-promoting TEA for A. sulfurireducens. PMID:23335768

Boyd, Eric S; Druschel, Gregory K

2013-03-01

197

In situ monitoring of sulfuric acid decomposition by Fourier transform infrared (FT-IR) spectroscopy in the sulfur iodine thermochemical reaction for the production of hydrogen  

Microsoft Academic Search

A potential way to produce large amounts of hydrogen for energy needs is the thermal breakdown of sulfuric acid (H2SO4) to oxygen, water, and sulfur dioxide (SO2). The sulfur dioxide can then be reacted with iodide to produce hydrogen iodide and ultimately hydrogen. In order to maximize the efficiency of the process it would be ideal to make in situ

Dion Rivera

2005-01-01

198

Quantification of Orotic Acid in Dried Filter-Paper Urine Samples by Stable Isotope Dilution  

Microsoft Academic Search

A rapid, sensitive, and specific method for quantification of orotic acid from dried filter-paper urine samples is described. The method involves stable isotope dilution with 1,3-(15N2)orotic acid and analysis by gas chroma- tography-mass spectrometry. The assay is sufficiently sensitive to be used with solvent extraction techniques commonly used for urinary organic acid analysis. Extrac- tion efficiencies of both native and

Mark T. McCann; Mark M. Thompson; Joni C. Gueron; Mendel Tuchman

199

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

PubMed

To investigate formation mechanism of secologanic acid sulfonates in sulfur-fumigated buds of Lonicera japonica, secologanic acid was enriched and purified from the sun-dried buds of L. japonica by various column chromatography on macroporus resin HPD-100, silica gel and ODS. The stimulation experiments of sulfur-fumigation process were carried out using secologanic acid reacted with SO2 in the aqueous solution. The reaction mechanism could be involved in the esterification or addition reaction. The present investigation provides substantial evidences for interpreting formation pathway of secologanic acid sulfonates in sulfur-fumigated buds of L. japonica. PMID:25095376

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

2014-05-01

200

Acid Rain  

Microsoft Academic Search

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

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

1979-01-01

201

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 (161.5°C, 9.44 min and 1.51% acid loading) gave 85.5% glucose yield, comparable to those of other commonly investigated feedstocks. Besides, the possibility of using fibers instead of finely ground biomass may be of economic interest. Oppositely, treatment with dilute alkali has shown lower performances under the conditions explored, most likely given the relatively significant lignin content, suggesting that the use of stronger alkali regime (with the associated drawbacks) is unavoidable to improve the performance of this treatment. PMID:24662312

Chiesa, S; Gnansounou, E

2014-05-01

202

A modified chromium-reducible sulfur method for reduced inorganic sulfur: optimum reaction time for acid sulfate soil  

Microsoft Academic Search

Reaction times for 16 acid sulfate soil materials analysed using a modified chromium-reducible sulfur method varied between 10 and 15 min, regardless of whether the samples had been dried and ground prior to analysis or were analysed without pretreatment. The reaction time for a ground ({\\\\textless}63 mm) pyritic rock sample was 20 min. An optimum reaction time of 20 min

L. A. Sullivan; R. T. Bush; D. M. McConchie

2000-01-01

203

Effect of atmospheric sulfur pollutants derived from acid precipitation on the benthic dynamics of lakes  

SciTech Connect

Sulfuric acid is a major contributor to acid precipitation in the United States. The relationship of acid precipitation to the sulfur dynamics of three lakes in New York was studied. For South Lake, which has probably been acidified, the sulfur profile in the sediment corresponded to historical changes in anthropogenic sulfur inputs. In all three study lakes, the organic sulfur constituents, which generally have been ignored in limnological investigations, played a major role in sulfur dynamics. The transformations and fluxes of inorganic and organic sulfur differed among the lakes and reflected characteristic abiotic and biotic properties, including productivity parameters. The community structure and secondary production of the invertebrate benthos were ascertained and, for South Lake, were similar to other acidified lakes. The importance of benthic insects on sulfur dynamics was demonstrated. Further studies on sulfur in lakes will enhance the understanding of the role of these anthropogenic inputs on lake systems and permit a more accurate appraisal of the present and future impacts of acidic deposition on water quality. 10 references.

Mitchell, M.J.

1982-11-01

204

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

SciTech Connect

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

Auburn University

2004-04-07

205

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

206

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

207

Change in the surface composition of the 08Kh14MF steel in sulfuric acid  

SciTech Connect

The nickel-free martensitic-ferritic steel 08Kh14MF exhibits considerable changes in its electrochemical properties under the action of mineral acid solutions. This paper deals with the changes in the chemical composition and the electrochemical properties of the surface of this steel as a function of time in a 1 N sulfuric acid solution at 20 +/- 2/sup 0/C and at different predetermined potentials. Sulfuric acid was selected as the most activating agent.

Zlobin, A.S.; Krutikov, P.G.; Mednikov, A.K.

1987-03-01

208

Thermal degradation of polyacrylic acid in dilute aqueous solution  

Microsoft Academic Search

The thermal degradation of polyacrylic acid of molecular weight (Mw) 5660 (PAA 5K) has been studied between 180 and 260 °C, representing the heat conditions prevailing at the high pressure heaters (185 °C) and steam generators (260 °C) of the steam-condensate cycle of CANDU nuclear power plants. The degradation does not follow a simple first-order kinetics but probably a rather complex mechanism that

Louis Lépine; Roland Gilbert

2002-01-01

209

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. Çetin; ?. Ero?lu; S. Özkar

2001-01-01

210

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

SciTech Connect

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

Zhao, Xin [JLAB; Corcoran, Sean G. [Virginia Tech; Kelley, Michael J. [W& amp; M, JLAB

2011-06-01

211

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

212

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. PMID:22074910

2011-01-01

213

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

SciTech Connect

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

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

1993-03-01

214

Case study, comparison of trial burn results from similar sulfuric acid regeneration plants  

SciTech Connect

The primary business of Rhodia Eco Services (Rhodia) is the regeneration of sulfuric acid. Sulfuric acid regeneration requires thermal decomposition of acid to sulfur dioxide, and remaking the acid through chemical reaction. The sulfuric acid regeneration furnace is the ideal place to process pumpable wastes for energy recovery and for thermal destruction. Rhodia is regulated by the Boiler and Industrial Furnace (BIF) regulations (40 CFR 266, Subpart H). The Hammond, Indiana plant is an interim status BIF facility and the Houston, Texas facility is renewing its RCRA incineration permit as a BIF facility. Both plants have conducted BIF Trial Burns with very similar results. The performance levels demonstrated were at levels better than RCRA/BIF standards for destruction and removal efficiency, metal, HCl/Cl, particulate, dioxin/furan, and organic emissions.

Milaszewski, M.; Johns, T. [Rhodia Inc., Hammond, IN (United States); Dickerson, W.F. [Rhodia Inc., Houston, TX (United States)

1998-12-31

215

Dilution and removal of dissolved metals from acid mine drainage along Imgok Creek, Korea  

Microsoft Academic Search

The dilution factors (Di) and removal fractions (Ri) of pollutants from acid mine drainage (AMD) were quantitatively estimated using two different methods, the conservative component and mass balance method, along Imgok Creek in Korea. The conservative component method assumes that SO4 is a perfectly conservative component and calculates Di and Ri from the concentration ratios of SO4. The mass balance

Jae-Young Yu; Bong Heo

2001-01-01

216

The effective dipole moments of isobutyric acid in the liquid state and dilute solutions in methanol  

Microsoft Academic Search

The dipole moments of isobutyric acid (I) were determined in the liquid state (?1) and dilute solutions in methanol (?1) at 20–50C. The permittivity of I in the liquid state was found to increase as the temperature grew, and the permittivity of solutions of I was lower than that of pure methanol; it decreased as the concentration of I and

A. Yu. Osadchev; T. P. Stepanova

2006-01-01

217

Sulfuric Acid-Water Chemical Energy-Storage System, Task 2.  

National Technical Information Service (NTIS)

This report summarizes the work performed during Task II of a four-task program investigating the use of the sulfuric acid-water system as a means of storing thermal energy. This Task II effort was concerned with the recombination aspects of the sulfuric ...

1976-01-01

218

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. Bal’zhinimaev; N. P. Belyaeva; S. I. Reshetnikov; E. S. Yudina; A. A. Ivanov

2001-01-01

219

Chromate tolerance in strains of Rhodosporidium toruloides modulated by thiosulfate and sulfur amino acids  

Microsoft Academic Search

Cr(VI) tolerance was studied in four strains of Rhodosporidium toruloides and compared with that of a fifth strain, DBVPG 6662, isolated from metallurgical wastes and known to be Cr(VI) resistant. Tolerance was studied in relation to different species of sulfur (sulfates, thiosulfates, methionine, cysteine) at different concentrations. Djenkolic acid, a poor source of sulfur and an activator of sulfate transport,

Milva Pepi; Franco Baldi

1995-01-01

220

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

221

Quantification of Pantothenic Acid and Folates by Stable Isotope Dilution Assays  

Microsoft Academic Search

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

Michael Rychlik; Achim Freisleben

2002-01-01

222

Prehydrolysis of xylan in culm of Sasa kurilensis with dilute sulphuric acid  

Microsoft Academic Search

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa kurilensis was hydrolysed with dilute sulphuric acid. A fermentable substrate with a relatively high xylose concentration (21.9?g?L?1) was obtained by hydrolysis with 2% sulphuric acid with a liquid to solid ratio of 10?:?1 at 121°C for 1?h. During hydrolysis\\u000a at elevated temperatures, some undesirable byproducts were also generated, such

Masahiro Miura; Keitaro Yokono; Housei Miyamoto; Masakazu Aoyama; Kiyoshi Tada; Jun-ichi Horiuchi; Yasuo Kojima; Chikara Sakai; Masahiro Nakahara

2010-01-01

223

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. Sal’nikov

2008-01-01

224

Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols  

Microsoft Academic Search

We used a general circulation model of Earth's climate to conduct geoengineering experiments involving stratospheric injection of sulfur dioxide and analyzed the resulting deposition of sulfate. When sulfur dioxide is injected into the tropical or Arctic stratosphere, the main additional surface deposition of sulfate occurs in midlatitude bands, because of strong cross-tropopause flux in the jet stream regions. We used

Ben Kravitz; Alan Robock; Luke Oman; Georgiy Stenchikov; Allison B. Marquardt

2009-01-01

225

On the stability and dynamics of (sulfuric acid) (ammonia) and (sulfuric acid) (dimethylamine) clusters: A first-principles molecular dynamics investigation  

NASA Astrophysics Data System (ADS)

The main pathway of new-particle formation in the atmosphere is likely to begin from small sulfuric acid clusters stabilized by other compounds, such as ammonia or amines. Here, we present the results of first-principles molecular dynamics simulations probing the stability and dynamics of (sulfuric acid) (ammonia/dimethylamine) clusters with two, three and four sulfuric acid molecules and a varying number of the bases. In each of the eight simulated clusters, an energetic equilibrium was reached and 35 ps of equilibrium data was collected in the NVT(T=300 K) ensemble. The clusters exhibited pronounced thermal motion including rotations of the molecules within the clusters. Regardless of the continuous movement, the clusters stayed bound together. The calculated electric dipole moments were found to be sensitive to the thermal motion and consequently, large fluctuations were observed. In addition, the vibrational spectra for all the clusters were determined, indicating that the thermal motion differs from purely harmonic motion.

Loukonen, V.; Kuo, I.-F. W.; McGrath, M. J.; Vehkamäki, H.

2014-01-01

226

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

E-print Network

the membrane. Therefore, we present a coupled mathematical and experimental study on the effect of water the concentration of sulfuric acid as a function of temperature, current density, pressure differential across

Weidner, John W.

227

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

228

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

PubMed

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

Hofmann, D J; Rosen, J M

1983-10-21

229

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming  

E-print Network

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster* (Received for publication, July iron-sulfur protein indicates a sulfur atom (S-1) of the iron-sulfur cluster and the sulfur atom (S

Trumpower, Bernard L.

230

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

E-print Network

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

Paris-Sud XI, Université de

231

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

232

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

233

Changes in the levels of major sulfur metabolites and free amino acids in pea cotyledons recovering from sulfur deficiency  

SciTech Connect

Changes in levels of sulfur metabolites and free amino acids were followed in cotyledons of sulfur-deficient, developing pea seeds (Pisum sativum L.) for 24 hours after resupply of sulfate, during which time the legumin mRNA levels returned almost to normal. Two recovery situations were studied: cultured seeds, with sulfate added to the medium, and seeds attached to the intact plant, with sulfate added to the roots. In both situations the levels of cysteine, glutathione, and methionine rose rapidly, glutathione exhibiting an initial lag. In attached but not cultured seeds methionine markedly overshot the level normally found in sulfur-sufficient seeds. In the cultured seed S-adenosylmethionine (AdoMet), but not S-methylmethionine, showed a sustained rise; in the attached seed the changes were slight. The composition of the free amino acid pool did not change substantially in either recovery situation. In the cultured seed the large rise in AdoMet level occurred equally in nonrecovering seeds. It was accompanied by 6-fold and 10-fold increases in ..gamma..-aminobutyrate and alanine, respectively. These effects are attributed to wounding resulting from excision of the seed. /sup 35/S-labeling experiments showed that there was no significant accumulation of label in unidentified sulfur-containing amino compounds in either recovery situation. It was concluded from these results and those of other workers that, at the present level of knowledge, the most probable candidate for a signal compound, eliciting recovery of legumin mRNA level in response to sulfur-feeding, is cysteine.

Macnicol, P.K.; Randall, P.J.

1987-02-01

234

Metal release from fly ash upon leaching with sulfuric acid or acid mine drainage  

SciTech Connect

Generation of electricity by coal-fired power plants produces large quantities of bottom ash and fly ash. New power plants commonly use fluidized bed combustion (FBC) boilers, which create ashes with high neutralization potential (NP). These ashes, due to their alkaline nature, are often used in surface mine reclamation to neutralize acidity and reduce hydraulic conductivity of disturbed overburdens. Conventional fly ashes from older power plants exhibit a range of pH and NP, with some ashes having neutral or acidic pH and low NP values, and may not be good candidates for supplying alkalinity in reclamation projects. In this study, the authors used two acidic solutions to leach a low NP fly ash (LNP ash) and two FBC ashes (FBC1 and FBC2). After passing 78 pore volumes of sulfuric acid and 129 pore volumes of acid mine drainage (AMD) through these ash materials several trace elements were found at high levels in the leachates. LNP fly ash leachates had high arsenic and selenium concentrations with sulfuric acid leaching, but showed low arsenic and selenium concentrations after leaching with AMD. Leaching with AMD caused the iron and aluminum inherent in AMD to complex these elements and make them unavailable for leaching. Lead, cadmium, and barium concentrations in fly ash leachates were not high enough to cause water pollution problems with either leaching solution. For both leaching solutions, manganese was released from LNP ash at a constant level, FBC1 ash did not release manganese, and FBC2 ash released manganese only after the NP had been exhausted by >60 pore volumes of leaching.

Skousen, J.; Bhumbla, D.K. [West Virginia Univ., Morgantown, WV (United States)

1998-12-31

235

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

236

Effect of reduced sulfur compounds on the fermentation of phosphoric acid pretreated sugarcane bagasse by ethanologenic Escherichia coli.  

PubMed

The addition of reduced sulfur compounds (thiosulfate, cysteine, sodium hydrosulfite, and sodium metabisulfite) increased growth and fermentation of dilute acid hydrolysate of sugarcane bagasse by ethanologenic Escherichia coli (strains LY180, EMFR9, and MM160). With sodium metabisulfite (0.5mM), toxicity was sufficiently reduced that slurries of pretreated biomass (10% dry weight including fiber and solubles) could be fermented by E. coli strain MM160 without solid-liquid separation or cleanup of sugars. A 6-h liquefaction step was added to improve mixing. Sodium metabisulfite also caused spectral changes at wavelengths corresponding to furfural and soluble products from lignin. Glucose and cellobiose were rapidly metabolized. Xylose utilization was improved by sodium metabisulfite but remained incomplete after 144 h. The overall ethanol yield for this liquefaction plus simultaneous saccharification and co-fermentation process was 0.20 g ethanol/g bagasse dry weight, 250 L/tonne (61 gal/US ton). PMID:21353535

Nieves, I U; Geddes, C C; Miller, E N; Mullinnix, M T; Hoffman, R W; Fu, Z; Tong, Z; Ingram, L O

2011-04-01

237

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

238

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

SciTech Connect

Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a microscopic molecular scale (from molecular sizes up to 2 nm) have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfuric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to particle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectrometer designed for measuring neutral clusters formed in the atmosphere during nucleation. An experimental technique, which we refer to as Semi-Ambient Signal Amplification (SASA), was employed. Sulfuric acid was added to ambient air, and the concentrations and composition of clusters in this mixture were analyzed by the Cluster CIMS. This experimental approach led to significantly higher cluster concentrations than are normally found in ambient air, thereby increasing signal-to-noise levels and allowing us to study reactions between gas phase species in ambient air and sulfuric acid containing clusters. Mass peaks corresponding to clusters containing four H{sub 2}SO{sub 4} molecules and one amine molecule were clearly observed, with the most abundant sulfuric acid-amine clusters being those containing a C2- or C4-amine (i.e. amines with masses of 45 and 73 amu). Evidence for C3- and C5-amines (i.e. amines with masses of 59 and 87 amu) was also found, but their correlation with sulfuric acid tetramer was not as strong as was observed for the C2- and C4-amines. The formation mechanisms for those sulfuric acid-amine clusters were investigated by varying the residence time in the inlet. It was concluded that the amines react directly with neutral clusters and that ion-induced clustering of sulfuric acid cluster ions with amines was not a dominant process. Results from ambient measurements using the Cluster CIMS without addition of sulfuric acid have shown that the sulfuric acid-amine clusters were reasonably well correlated with sulfuric acid tetramer and consistent with the SASA experiments at the same Boulder sampling site. Also, clusters that contain C2- or C4-amines were more abundant and better correlated with sulfuric acid tetramer than other types of amine containing clusters. However, ambient measurements of sulfuric acid-amine clusters remain difficult and highly uncertain because their concentrations are only slightly above background levels, even during nucleation events.

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

2011-11-02

239

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.

240

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

PubMed

The production of fermentable sugars from olive tree biomass was studied by dilute acid pretreatment and further saccharification of the pretreated solid residues. Pretreatment was performed at 0.2%, 0.6%, 1.0% and 1.4% (w/w) sulphuric acid concentrations while temperature was in the range 170-210 degrees C. Attention is paid to sugar recovery both in the liquid fraction issued from pretreatment (prehydrolysate) and that in the water-insoluble solid (WIS). As a maximum, 83% of hemicellulosic sugars in the raw material were recovered in the prehydrolysate obtained at 170 degrees C, 1% sulphuric acid concentration, but the enzyme accessibility of the corresponding pretreated solid was not very high. In turn, the maximum enzymatic hydrolysis yield (76.5%) was attained from a pretreated solid (at 210 degrees C, 1.4% acid concentration) in which cellulose solubilization was detected; moreover, sugar recovery in the prehydrolysate was the poorest one among all the experiments performed. To take account of fermentable sugars generated by pretreatment and the glucose released by enzymatic hydrolysis, an overall sugar yield was calculated. The maximum value (36.3 g sugar/100 g raw material) was obtained when pretreating olive tree biomass at 180 degrees C and 1% sulphuric acid concentration, representing 75% of all sugars in the raw material. Dilute acid pretreatment improves results compared to water pretreatment. PMID:17498947

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

2008-04-01

241

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 56.20 g/L and 69.43% at the 30% solids loading and 15 FPU/DM cellulase dosage, respectively, corresponding to a 26.5% increase in ethanol titer and 17.2% increase in ethanol yield at the same fermentation conditions. Conclusions The advantage of helically agitated mixing may provide a prototype of dry dilute acid pretreatment processing for future commercial-scale production of cellulosic ethanol. PMID:24387051

2014-01-01

242

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

PubMed

A molecular beam technique has been used to study the dynamics and mass accommodation of HCl molecules in collision with sulfuric acid-water surfaces. The experiments were performed by directing a nearly mono-energetic beam of HCl molecules onto a continuously renewed liquid film of 54-76 wt% sulfuric acid at temperatures between 213 K and 243 K. Deuterated sulfuric acid was used to separate sticking but non-reactive collisions from those that involved penetration through the phase boundary followed by dissociation and recombination with D+. The results indicate that the mass accommodation of HCl on sulfuric acid-water surfaces decreases sharply with increasing acidity over the concentration range 54-76 wt%. Using the capillary wave theory of mass accommodation this effect is explained by a change of the surface dynamics. Regarding the temperature dependence it is found that the mass accommodation of HCl increases with increasing temperature and is limited by the bulk phase viscosity and driven by the restoring forces of the surface tension. These findings imply that under atmospheric conditions the uptake of HCl from the gas phase depends crucially on the bulk phase parameters of the sulfuric acid aerosol. PMID:19727512

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

2009-09-28

243

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

244

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

245

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

246

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

E-print Network

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

Hale, Barbara N.

247

Nafion membranes modified with silica sulfuric acid for the elevated temperature and lower humidity operation of PEMFC  

Microsoft Academic Search

Nafion membranes modified with silica and silica sulfuric acid are fabricated for the elevated temperature and lower humidity operation of proton-exchange membrane fuel cells. An incorporation of silica sulfuric acid promotes the amorphous phase which in turn influences the segmental motion of polymeric chains. By the endeavor of sulfonic acid moieties, ion channels are extended and facilitate the high ionic

G. Gnana Kumar; A. R. Kim; Kee Suk Nahm; R. Elizabeth

2009-01-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

249

Relative contributions of sulfuric and nitric acids in acid rain to the acidification of the ecosystem: implications for control strategies  

SciTech Connect

Much of northeastern North America has been receiving precipitation of pH 4.6 or less, i.e. more than ten times more acid than normal rain (pH = 5.6) for at least the past 20 to 30 years. Originally, this acidity was almost totally due to sulfuric acid. These inputs of sulfuric acid in the very acid sensitive Adirondacks may have removed much of the neutralizing and nitrate-utilizing ability of the soils and water. Thus, this area may now be more sensitive to atmospheric inputs of nitric acid. Further work is required on the impact of acid nitrate deposition on the ecosystem but with equal certainty it can be stated that sulfur deposition remains the princpial long term threat to acid sensitive ecosystems. It can be concluded that: much of the nitric acid in acid rain is decomposed in the soils and waterway, and is not a significant contributor to long-term acidification of soils and waters; although in the long term, nitric acid in atmospheric deposition is not likely to be contributing to the overall acidification of the environment, during the spring thaw, in areas which have been heavily impacted by acid rain for a number of years, nitric acid which has concentrated in the snow pack over the winter may cause ecological damage, especially to fish populations; though there is little doubt that tighter control strategies are necessary to diminish the effects of acid rain on remote ecosystems the existing control strategies, which have put more emphasis on the control of emissions of sulfur oxides than nitrogen oxides, have a reasonable scientific basis given our present limited knowledge of their effects on the ecosystem.

McLean, R.A.N.

1981-11-01

250

Ammonia Adsorption on Bamboo Charcoal with Acid Treatment  

Microsoft Academic Search

The effect of ammonia adsorption in aqueous solutions was examined for bamboo charcoal carbonized at 400, 700 and 1000°C, and activated carbon. Furthermore, the change of the ammonia adsorption in aqueous solutions was also examined by treatment of each sample with diluted sulfuric acid. Bamboo charcoal carbonized at 400°C and treated with diluted sulfuric acid was the most effective for

Takashi Asada; Takashi Ohkubo; Kuniaki Kawata; Kikuo Oikawa

2006-01-01

251

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

252

Bimodal distribution of sulfuric acid aerosols in the upper haze of Venus  

NASA Astrophysics Data System (ADS)

Observations by the SPICAV/SOIR instruments aboard Venus Express have revealed that the upper haze (UH) of Venus, between 70 and 90 km, is variable on the order of days and that it is populated by two particle modes. We use a one-dimensional microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two observed modes, and whether their observed variability are due in part to the action of vertical transient winds at the cloud tops. Nucleation of photochemically produced sulfuric acid onto polysulfur condensation nuclei generates mode 1 cloud droplets, which then diffuse upwards into the UH. Droplets generated in the UH from nucleation of sulfuric acid onto meteoric dust coagulate with the upwelled cloud particles and therefore cannot reproduce the observed bimodal size distribution. By comparison, the mass transport enabled by transient winds at the cloud tops, possibly caused by sustained subsolar cloud top convection, are able to generate a bimodal size distribution in a time scale consistent with Venus Express observations. Below the altitude where the cloud particles are generated, sedimentation and vigorous convection causes the formation of large mode 2 and mode 3 particles in the middle and lower clouds. Evaporation of the particles below the clouds causes a local sulfuric acid vapor maximum that results in upwelling of sulfuric acid back into the clouds. In the case where the polysulfur condensation nuclei are small and their production rate is high, coagulation of small droplets onto larger droplets in the middle cloud may set up an oscillation in the size modes of the particles such that precipitation of sulfuric acid “rain” may be possible immediately below the clouds once every few Earth months. Reduction of the polysulfur condensation nuclei production rate destroys this oscillation and reduces the mode 1 particle abundance in the middle cloud by two orders of magnitude. However, it better reproduces the sulfur-to-sulfuric-acid mass ratio in the cloud and haze droplets as constrained by fits to UV reflectivity data. In general we find satisfactory agreement between our nominal and transient wind results and observations from Pioneer Venus, Venus Express, and Magellan, though improvements could be made by incorporating sulfur microphysics.

Gao, Peter; Zhang, Xi; Crisp, David; Bardeen, Charles G.; Yung, Yuk L.

2014-03-01

253

Bimodal Distribution of Sulfuric Acid Aerosols in the Upper Haze of Venus  

E-print Network

The upper haze (UH) of Venus is variable on the order of days and it is populated by two particle modes. We use a 1D microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two size modes and whether their observed variability are due to cloud top vertical transient winds. Nucleation of photochemically produced sulfuric acid onto polysulfur condensation nuclei generates mode 1 cloud droplets that then diffuse upwards into the UH. Droplets generated in the UH from nucleation of sulfuric acid onto meteoric dust coagulate with the upwelled cloud particles and cannot reproduce the observed bimodal size distribution. The mass transport enabled by cloud top transient winds are able to generate a bimodal size distribution in a time scale consistent with observations. Sedimentation and convection in the middle and lower...

Gao, Peter; Crisp, David; Bardeen, Charles G; Yung, Yuk L

2013-01-01

254

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

PubMed

Heavy metals contaminated wastewater sludge is classified as hazardous solid waste and needs to be properly treated to prevent releasing heavy metals to the environment. In this study, the wastewater treatment sludge from a printed circuit board manufacturing plant was treated in a batch reactor by sulfuric acid to remove the contained heavy metals. The effects of sulfuric acid concentration and solid to liquid ratio on the heavy metal removal efficiencies were investigated. The experimental results showed that the total and individual heavy metal removal efficiencies increased with increasing sulfuric acid concentration, but decreased with increasing solid to liquid ratio. A mathematical model was developed to predict the residual sludge weights at varying sulfuric concentrations and solid to liquid ratios. The trivalent heavy metal ions, iron and chromium were more difficult to be removed than the divalent ions, copper, zinc, nickel, and cadmium. For 5 g/L solid to liquid ratio, more than 99.9% of heavy metals can be removed from the sludge by treating with 0.5M sulfuric acid in 2h. PMID:20079970

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

2010-05-15

255

Process for recovery of sulfur from acid gases  

DOEpatents

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

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

1995-01-01

256

Diffusion of aqueous carbon dioxide, sulfur dioxide, sulfuric acid, and ammonia at very low concentrations  

SciTech Connect

Equations are developed to predict binary diffusion coefficients, D, for very dilute aqueous solutions of CO/sub 2/, SO/sub 2/, and NH/sub 3/. As the concentration of each solute drops, D initially rises because a higher proportion of rapidly diffusing H/sup +/ or OH/sup -/ ions is produced by hydrolysis (CO/sub 2/ + H/sub 2/O = H/sup +/ HCO/sub 3//sup -/, SO/sub 2/ + H/sub 2/O = HSO/sub 3//sup -/, or NH/sub 3/ + H/sub 2/O = OH/sup -/ + NH/sub 4//sup +/). The diffusion coefficients reach maximum values at concentrations near 10/sup -6/ mol L/sup -1/. At lower concentrations where H/sup +/ and OH/sup -/ ions produced by dissociation of water are no longer negligible, values of D decrease by 30-50% and approach limiting diffusivities of the solute ions. Values of D for dilute aqueous solutions of H/sub 2/OSO/sub 4/ are also reported.

Leaist, D.G.

1987-08-13

257

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

258

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

PubMed

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

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

2010-01-01

259

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

NASA Astrophysics Data System (ADS)

Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to the formation and early growth of nucleated particles. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and ?-pinene) showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two chemical ionization mass spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene. New analysis methods were applied to the data collected with a condensation particle counter battery and a scanning mobility particle sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (?), defined as the ratio between the measured growth rate in the presence of ?-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed ? values indicate that the growth is already dominated by organic compounds at particle diameters of 2 nm. Both the absolute growth rates and ? showed a strong dependence on particle size, supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particle growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. Finally, the size resolved growth analysis indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

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

2012-10-01

260

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

NASA Astrophysics Data System (ADS)

Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to formation and to the early growth of nucleated particles, respectively. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and ?-pinene) showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two Chemical Ionization Mass Spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene. New analysis methods were applied to the data collected with a Condensation Particle Counter battery and a Scanning Mobility Particle Sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (?), defined as the ratio between the measured growth rate in the presence of ?-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed ? values indicate that the growth is dominated by organic compounds already at particle diameters of 2 nm. Both the absolute growth rates and ? showed a strong dependence on particle size supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particles growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. The size resolved growth analysis finally indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

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

2012-05-01

261

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

SciTech Connect

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

Ketusky, E

2008-07-11

262

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

263

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

NASA Astrophysics Data System (ADS)

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

Peji?, N.; Vujkovi?, M.; Maksimovi?, J.; Ivanovi?, A.; Ani?, S.; ?upi?, Ž.; Kolar-Ani?, Lj.

2011-12-01

264

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 µM 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 µM, 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

265

Vibrational Spectroscopy of Bisulfate/Sulfuric Acid/Water Clusters: Structure, Stability, and Infrared Multiple-Photon Dissociation  

E-print Network

Vibrational Spectroscopy of Bisulfate/Sulfuric Acid/Water Clusters: Structure, Stability, and Infrared Multiple-Photon Dissociation Intensities Tara I. Yacovitch, Nadja Heine, Claudia Brieger, Torsten of mass-selected bisulfate, sulfuric acid, and water cluster anions, HSO4 - (H2SO4)m(H2O)n, are studied

Neumark, Daniel M.

266

Methane sulfonic acid enhanced formation of molecular clusters of sulfuric acid and dimethyl amine  

NASA Astrophysics Data System (ADS)

Over oceans and in coastal regions methane sulfonic acid (MSA) is present in substantial concentrations in aerosols and in the gas phase. We present an investigation of the effect of MSA on sulfuric acid and dimethyl amine (DMA) based cluster formation rates. From systematic conformational scans and well tested ab initio methods, we optimize structures of all MSAx (H2SO4)yDMAz clusters where x + y ≤ 3 and z ≤ 2. The resulting thermodynamic data is used in the Atmospheric Cluster Dynamics Code and the effect of MSA is evaluated by comparing ternary MSA-H2SO4-DMA cluster formation rates to binary H2SO4-DMA cluster formation rates. Within the range of atmospherically relevant MSA concentrations, we find that MSA may increase cluster formation rates by up to one order of magnitude, although typically, the increase will be less than 300% at 258 K, less than 100% at 278 K and less than 15% at 298 K. The results are rationalized by a detailed analysis of the the main growth paths of the clusters. We find that MSA enhanced clustering involves clusters containing one MSA molecule, while clusters containing more than one MSA molecule do not contribute significantly to the growth.

Bork, N.; Elm, J.; Olenius, T.; Vehkamäki, H.

2014-07-01

267

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

268

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. PMID:23356640

2013-01-01

269

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

270

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

SciTech Connect

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

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

1991-07-01

271

Determination of vertical fluxes of sulfur dioxide and dimethyl sulfide in the remote marine atmosphere by eddy correlation and an airborne isotopic dilution atmospheric pressure ionization mass spectrometer  

NASA Astrophysics Data System (ADS)

Vertical fluxes of dimethyl sulfide (DMS) and sulfur dioxide (SO 2) were determined by eddy correlation and an isotopic dilution atmospheric pressure ionization mass spectrometer (APIMS) on an aircraft platform. The sampling frequency of the isotopic dilution APIMS ranged from 1 Hz to 25 Hz for real-time measurements. Measurements were made near the surface in the marine boundary layer to over 6 km in the free troposphere. The APIMS demonstrated an average sensitivity of 80 cps/pptv for DMS and SO2 with a signal-to-noise (S/N) ratio > 5. A lower limit of detection of 0.1 pptv in a one second integration period was also determined for DMS and SO2 in airborne atmospheric measurements. Use of the isotopic dilution technique provided an internal calibration of every ambient sample along with manifold conditioning for rapid and efficient transport of the ambient species through the manifold. As a result the eddy correlation flux determinations were accurate, precise, and reproducible. Laboratory results suggest the addition of ozone in excess of 45 ppbv to the APIMS sampling manifold to ensure unaltered formation of SO5 - ion (the ion detected for SO2). Use of a Nafion dryer was warranted for sensitive APIMS detection of SO2 in humid air. A Nafion dryer along with an air temperature of 400°C was required for sensitive APIMS detection of DMS in humid air. Results from an initial airborne test deployment in continental air include a successful SO2 intercomparison between the APIMS and a GC/MS/ILS (isotopically labeled standard-gas chromatography/mass spectrometer). Fast SO2 measurements in thin moist layers and pollution plumes demonstrated the utility of the fast isotopic dilution APIMS technique. Results from a second airborne test deployment in the remote marine boundary layer include a successful DMS intercomparison and eddy correlation fluxes of DMS and SO2 from isotopic dilution APIMS measurements. The average DMS flux near the surface was (1.7 +/- 0.2) × 1013 molecules m-2 s-1. A flux gradient for DMS generated a DMS surface flux of (2.3 +/- 0.7) × 10 13 molecules in m-2 s-1 and a DMS entrainment flux of (7.5 +/- 4.4) × 1012 molecules m-2 s-1. High resolution altitude profiles of DMS allowed for the determination of the DMS entrainment velocity (1.9 +/- 1.1 cm/s). A SO2 flux of (4.3 +/- 1.9) × 1012 molecules m-2 s-1 and a deposition velocity of 2.4 +/- 1.1 mm/s also was determined. All values reported are in good agreement with the literature.

Mitchell, Glenn M.

2001-08-01

272

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...

273

OPERATION OF A SULFURIC ACID PLANT USING BLENDED COPPER SMELTER GASES  

EPA Science Inventory

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

274

Influence of polymer addition on biogenic sulfuric acid attack of concrete  

Microsoft Academic Search

A simple and reproducible microbiological simulation procedure in combination with a chemical procedure was used to test concrete for its potential resistance towards biogenic sulfuric acid. Concerning fundamental aspects of the corrosion reaction, it was shown that particularly the penetration of H2S inside the concrete crevices accelerated the corrosion process. The influence of different polymer types and silica fume additions

Elke Vincke; Ellen Van Wanseele; Joke Monteny; Anne Beeldens; Nele De Belie; Luc Taerwe; Dionys Van Gemert; Willy Verstraete

2002-01-01

275

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

276

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

277

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

278

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

279

Biochemical changes in humans upon exposure to sulfuric acid aerosol and exercise. Research report  

Microsoft Academic Search

A total of 18 human subjects were exposed to ambient air for four hours on the first day of exposure and to four hours of 100 micrograms\\/cu. m. (0.033 micromole) sulfuric acid aerosol exposed to four hours of ambient air on both exposure days. Six biochemical blood parameters were measured pre and post exposure: glutathione, lysozyme, glutathione reductase, serum glutamic

S. Chaney; W. Blomquist; K. Muller; G. Goldstein

1979-01-01

280

EFFECTS OF LARGE (0.9 MICROMETER) SULFURIC ACID AEROSOLS ON HUMAN PULMONARY FUNCTION  

EPA Science Inventory

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...

281

Ortho-, meta-, and para-aminophenol-N-salicylidenes as corrosion inhibitors of zinc in sulfuric acid  

Microsoft Academic Search

Purpose – The evaluation of Schiff bases derived from o-, m- and p-aminophenols and salicylaldehyde as corrosion inhibitors of zinc in sulfuric acid and to study their action mechanism. Design\\/methodology\\/approach – The effect of various parameters on the behaviour of these inhibitors has been studied using the weight loss and polarization measurements. Findings – In general, the ortho isomer was

J. D. Talati; M. N. Desai; N. K. Shah

2005-01-01

282

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...

283

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

EPA Science Inventory

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

284

An inlet\\/sampling duct for airborne OH and sulfuric acid measurements  

Microsoft Academic Search

An inlet assembly has been designed, tested, and used for the airborne measurements of OH and sulfuric acid. The inlet sampling duct, which incorporates a shroud connected to two nested, restricted flow ducts, slows air velocity by approximately a factor of 16 while maintaining a uniform and well-defined flow. Qualitative wind tunnel tests showed that an inlet shroud that incorporates

F. L. Eisele; R. L. Mauldin; D. J. Tanner; J. R. Fox; T. Mouch; T. Scully

1997-01-01

285

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

EPA Science Inventory

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

286

The role of cluster energy nonaccommodation in atmospheric sulfuric acid nucleation  

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

287

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

288

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

Microsoft Academic Search

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

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

1998-01-01

289

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

Code of Federal Regulations, 2012 CFR

...requirement of a tolerance when used in accordance with good agricultural practice when used as a herbicide in the production of garlic and onions, and as a potato vine dessicant in the production of potatoes. (b) Residues of sulfuric acid are...

2012-07-01

290

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

Code of Federal Regulations, 2011 CFR

...requirement of a tolerance when used in accordance with good agricultural practice when used as a herbicide in the production of garlic and onions, and as a potato vine dessicant in the production of potatoes. (b) Residues of sulfuric acid are...

2011-07-01

291

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

Code of Federal Regulations, 2010 CFR

...requirement of a tolerance when used in accordance with good agricultural practice when used as a herbicide in the production of garlic and onions, and as a potato vine dessicant in the production of potatoes. (b) Residues of sulfuric acid are...

2010-07-01

292

INVESTIGATIONS ON THE MECHANISMS OF SULFURIC ACID LEACHING OF CHALCOPYRITE IN THE PRESENCE OF HYDROGEN PEROXIDE  

Microsoft Academic Search

The sulfuric acid leaching behavior of chalcopyrite in the presence of hydrogen peroxide was studied at 25°C using electrochemical techniques. The effects of increasing the concentrations of hydrogen peroxide up to 3 M on chalcopyrite dissolution were carried out in shake flasks prior to electrochemical studies. Electrochemical investigations were carried out on particulates electrode made from powdered chalcopyrite samples using potentiodynamic

P. A. Olubambi; J. H. Potgieter

2009-01-01

293

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

PubMed

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

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

2014-10-01

294

Sulfur amino acid metabolism in doxorubicin-resistant breast cancer cells  

SciTech Connect

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

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

2011-08-15

295

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

SciTech Connect

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

Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P. (Syracuse Univ., NY (USA))

1988-06-01

296

Effects of High-Dose Folic Acid and Pyridoxine on Plasma and Erythrocyte Sulfur Amino Acids in Hemodialysis Patients  

Microsoft Academic Search

In this investigation, sulfur amino acids (sAA) and sulfhydryls were determined in the plasma and erythrocytes (RBC) of 10 uremic patients on regular hemodialysis (HD) treatment and 10 healthy subjects, before and after supplemen- tation with 15 mg\\/d of folic acid and 200 mg\\/d of pyridoxine for 4 wk. The basal total plasma concentrations of homocys- teine (Hcy), cysteine (Cys),

MOHAMED E. SULIMAN; JOS ´ E C. DIVINO FILHO; ORN ANDERSTAM; BENGT LINDHOLM

1999-01-01

297

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: IV Acid–sulfate waters  

Microsoft Academic Search

Many waters sampled in Yellowstone National Park, both high-temperature (30–94°C) and low-temperature (0–30°C), are acid–sulfate type with pH values of 1–5. Sulfuric acid is the dominant component, especially as pH values decrease below 3, and it forms from the oxidation of elemental S whose origin is H2S in hot gases derived from boiling of hydrothermal waters at depth. Four determinations

D. Kirk Nordstrom; R. Blaine McCleskey; James W. Ball

2009-01-01

298

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

299

Effects of temperature and moisture on dilute-acid steam explosion pretreatment of corn stover and cellulase enzyme digestibility  

Microsoft Academic Search

Corn stover is emerging as a viable feedstock for producing bioethanol from renewable resources. Dilute-acid pretreatment\\u000a of corn stover can solubilize a significant portion of the hemicellulosic component and enhance the enzymatic digestibility\\u000a of the remaining cellulose for fermentation into ethanol. In this study, dilute H2SO4 pretreatment of corn stover was performed in a steam explosion reactor at 160°C, 180°C,

Melvin P. Tucker; Kyoung H. Kim; Mildred M. Newman; Quang A. Nguyen

2003-01-01

300

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

301

Development of Sulfuric Acid Decomposer for Thermo-Chemical IS Process  

SciTech Connect

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

Hiroki, Noguchi; Hiroyuki, Ota; Atsuhiko, Terada; Shinji, Kubo; Kaoru, Onuki [IS Process Technology Group, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency (JAEA) 4002 Narita, Oarai, Higashiibaraki, Ibaraki 311-1393 (Japan); Ryutaro, Hino [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency (JAEA), 4002 Narita, Oarai, Higashiibaraki, Ibaraki 311-1393 (Japan)

2006-07-01

302

Chemolithotrophic bacteria in copper ores leached at high sulfuric Acid concentration.  

PubMed

Extensive bacterial growth was observed when copper sulfide ores were leached with 0.6 N sulfuric acid. The bacterial population developed in this condition was examined by characterization of the spacer regions between the 16S and 23S rRNA genetic loci obtained after PCR amplification of the DNA extracted from the leached ore. The spacers observed had the sizes found in strains of "Leptospirillum ferrooxidans" and Thiobacillus thiooxidans, except for a larger one, approximately 560 bp long, that was not observed in any of the strains examined, including those of Thiobacillus ferrooxidans. The bacteria with this last spacer were selected after culturing in mineral and elemental sulfur media containing 0.7 N sulfuric acid. The spacer and the 16S ribosomal DNA of this isolate were sequenced and compared with those in species commonly found in bioleaching processes. Though the nucleotide sequence of the spacer showed an extensive heterologous region with T. thiooxidans, the sequence of its 16S rDNA gene indicated a close relationship (99.85%) with this species. These results indicate that a population comprised of bacterial strains closely related to T. thiooxidans and of another strain, possibly related to "L. ferrooxidans," can develop during leaching at high sulfuric acid concentration. Iron oxidation in this condition is attributable to "L. ferrooxidans" and not T. ferrooxidans, based on the presence of spacers with the "L. ferrooxidans" size range and the absence of spacers characteristic of T. ferrooxidans. PMID:16535497

Vasquez, M; Espejo, R T

1997-01-01

303

Microbial contributions to cave formation: New insights into sulfuric acid speleogenesis  

NASA Astrophysics Data System (ADS)

The sulfuric acid speleogenesis (SAS) model was introduced in the early 1970s from observations of Lower Kane Cave, Wyoming, and was proposed as a cave-enlargement process due to primarily H2S autoxidation to sulfuric acid and subaerial replacement of carbonate by gypsum. Here we present a reexamination of the SAS type locality in which we make use of uniquely applied geochemical and microbiological methods. Little H2S escapes to the cave atmosphere, or is lost by abiotic autoxidation, and instead the primary H2S loss mechanism is by subaqueous sulfur-oxidizing bacterial communities that consume H2S. Filamentous “Epsilonproteobacteria” and Gammaproteobacteria, characterized by fluorescence in situ hybridization, colonize carbonate surfaces and generate sulfuric acid as a metabolic byproduct. The bacteria focus carbonate dissolution by locally depressing pH, compared to bulk cave waters near equilibrium or slightly supersaturated with calcite. These findings show that SAS occurs in subaqueous environments and potentially at much greater phreatic depths in carbonate aquifers, thereby offering new insights into the microbial roles in subsurface karstification.

Summers Engel, Annette; Stern, Libby A.; Bennett, Philip C.

2004-05-01

304

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

305

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

PubMed

This study was conducted to characterize shortday onions of 3 pungency levels with regard to the composition of flavor related compounds. A total of 9 onion breeding lines/cultivars were selected, per each of low, medium, and high pungency level, with pyruvic acid contents of 1.9 to 2.8, 4.8 to 5.4, and 7.2 to 8.3 micromoles/mL, respectively. The contents of flavor precursors (S-1-propenyl-L-cysteine sulfoxide [1-PeCSO] and S-methyl-L-cysteine-sulfoxide [MCSO]), free amino acids, free sugars, soluble solids (SSC), and total sulfur (S) in onion bulbs were measured. The flavor precursor contents ranged from 0.03 to 0.16 mg/g fresh weight (FW) for MCSO, 0.07 to 0.65 mg for 1-PeCSO, and 0.12 to 0.77 mg in total, and precursor contents increased with the pungency levels. Onions of different pungency levels did not differ in the contents of individual or total free amino acids, and the most abundant amino acids were glutamine and arginine. The total sugar contents ranged from 50 to 75 mg/g FW, and total S contents (3.5 to 5.1 mg/g dry weight) were not correlated with the pungency levels. However, pungency levels were correlated inversely with bulb weight and positively with SSC, presumably by the effect of dilution. This study indicates that onion pungency is primarily determined by the content of flavor precursor compounds and not by total S, total sugars, or individual/total free amino acids in shortday bulbs. PMID:19723185

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

2009-08-01

306

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

307

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

PubMed Central

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

Wang, Wenhua; Simon, Martin; Wu, Feihua; Hu, Wenjun; Chen, Juan B.; Zheng, Hailei

2014-01-01

308

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

309

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

310

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

311

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. PMID:22369467

2012-01-01

312

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

PubMed

The pretreatment of lignocellulosic materials prior to the enzymatic hydrolysis is essential to the sugar yield and bioethanol production. Dilute acid hydrolysis of black spruce softwood chip was performed in a continuous high temperature reactor followed with steam explosion and mechanical refining. The acid-soaked wood chips were pretreated under different feeding rates (60 and 92 kg/h), cooking screw rotation speeds (7.2 and 14.4 rpm), and steam pressures (12 and 15 bar). The enzymatic hydrolysis was carried out on the acid-insoluble fraction of pretreated material. At lower feeding rate, the pretreatment at low steam pressure and short retention time favored the recovery of hemicellulose. The pretreatment at high steam pressure and longer retention time recovered less hemicellulose but improved the enzymatic accessibility. As a result, the overall sugar yields became similar no matter what levels of the retention time or steam pressure. Comparing with lower feeding rate, higher feeding rate resulted in consistently higher glucose yield in both liquid fraction after pretreatment and that released after enzymatic hydrolysis. PMID:20725804

Fang, Haixia; Deng, James; Zhang, Tony

2011-02-01

313

Photoluminescent properties of anodic aluminum oxide films formed in a mixture of malonic and sulfuric acid  

NASA Astrophysics Data System (ADS)

Anodic aluminum oxide (AAO) films with ordered nanopore arrays were fabricated electrochemically in the mixture electrolytes of malonic and sulfuric acids. Their photoluminescent (PL) properties have been investigated. There is no obvious PL band for the AAO films prepared in pure sulfuric acid, however, with the increase of the concentration of malonic acid in the mixture electrolytes, a PL band in the range from 300 to 500 nm appears, and its intensity is enhanced gradually. Obviously, the PL band is mainly attributed to the malonic impurities incorporated into AAO films, which corresponds to the excitation center at about 270 nm. Meantime, the increase of the sulfuric acid concentration results in a blueshift of the PL band. Further, the effect of annealing process on the PL properties is also investigated. As annealing temperature increases, the malonic impurities incorporated into AAO films are gradually decomposed, the PL intensity corresponding to excitation center at about 270 nm gradually becomes weak. But interestingly, with the decomposition of malonic impurities, the defects in AAO films mainly caused by a lattice mismatch and the difference in the coefficients of thermal expansion between alumina and incorporated malonic impurities are gradually produced, which form a new excitation center at about 250 nm, and its PL is firstly enhanced to maximum at 400 °C and then decreases with the further increase of annealing temperature.

Li, Shou-Yi; Wang, Jian; Li, Yan; Zhang, Xu-Qiang; Wang, Gang; Wang, Cheng-Wei

2014-11-01

314

Electrical charging changes the composition of sulfuric acid-ammonia/dimethylamine clusters  

NASA Astrophysics Data System (ADS)

Sulfuric acid clusters stabilized by base molecules are likely to have a significant role in atmospheric new-particle formation. Recent advances in mass spectrometry techniques have permitted the detection of electrically charged clusters. However, direct measurement of electrically neutral clusters is not possible. Mass spectrometry instruments can be combined with a charger, but the possible effect of charging on the composition of neutral clusters must be addressed in order to interpret and understand the measured data. In the present work we have used formation free energies from quantum chemical methods to calculate the evaporation rates of electrically charged (both positive and negative) sulfuric acid-ammonia/dimethylamine clusters. To understand how charging will affect the composition of electrically neutral clusters, we have compared the evaporation rates of the most stable neutral clusters with those of the corresponding charged clusters. Based on the evaporation rates of different molecules from the charged clusters, we determined the most likely resulting cluster composition when a stable neutral cluster is charged and the molecules with the highest evaporation rates are lost from it. We found that all of the most stable neutral clusters will be altered by both positive and negative charging. In the case of charging clusters negatively, base molecules will completely evaporate from clusters with 1 to 3 sulfuric acid molecules in the case of ammonia, and from clusters with 1 or 2 sulfuric acid molecules in the case of dimethylamine. Larger clusters will maintain some base molecules, but the H2SO4 : base ratio will increase. In the case of positive charging, some of the acid molecules will evaporate, decreasing the H2SO4 : base ratio.

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

2014-08-01

315

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

316

Conductance of Dilute Sodium Acetate Solutions to 469 K and of Acetic Acid and Sodium Acetate\\/Acetic Acid Mixtures to 548 K and 20 MPa  

Microsoft Academic Search

In order to obtain accurate association constants for sodium acetate, a very precise flow method was used to measure the electrical conductivity of dilute aqueous solutions of sodium acetate at ambient conditions and 469 K and 20 MPa. Measurements at ambient conditions, 469 and 548 K and 20 MPa, were also made on sodium acetate\\/acetic acid mixtures and acetic acid.

G. H. Zimmerman; R. H. Wood

2002-01-01

317

Heterogeneous interactions of chlorine nitrate, hydrogen chloride, and nitric acid with sulfuric acid surfaces at stratospheric temperatures  

NASA Technical Reports Server (NTRS)

The heterogeneous interactions of ClONO2, HCl, and HNO3 with sulfuric acid surfaces were studied using a Knudsen cell flow reactor. The surfaces studied, chosen to simulate global stratospheric particulate, were composed of 65-75 percent H2SO4 solutions at temperatures in the range -63 to -43 C. Heterogeneous loss, but not reaction, of HNO3 and HCl occurred on these surfaces; the measured sticking coefficients are reported. Chlorine nitrate reacted on the cold sulfuric acid surfaces, producing gas-phase HOCl and condensed HNO3. CLONO2 also reacted with HCl dissolved in the 65-percent H2SO4 solution at -63 C, forming gaseous Cl2. In all cases studied, the sticking and/or reaction coefficients were much larger for the 65-percent H2SO4 solution at -63 C than for the 75-percent solution at -43 C.

Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

1988-01-01

318

Effect of gelling on the surface structure of a porous lead electrode in sulfuric acid  

Microsoft Academic Search

Effect of immobilizing the electrolyte using thixotropic agents such as sodium silicate on the electrochemical behaviour of lead in sulfuric acid is studied using electrochemical methods such as cyclic voltammetry (CV), charging curve technique, Tafel polarization and surface spectroscopic methods including X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). CV studies indicate a 700mV cathodic shift in the hydrogen

M. P. VINOD; A. B. MANDLE; S. R. SAINKAR; K. VIJAYAMOHANAN

1997-01-01

319

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

NASA Technical Reports Server (NTRS)

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

Golombek, Amram; Prinn, Ronald G.

1993-01-01

320

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

1987-01-01

321

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\\/[m2·d]) was measured using model reactors located on

Shin Hirayama; Masashi Miyasaka; Hideomi Amano; Yoshito Kumagai; Nobuhiro Shimojo; Teruyoshi Yanagita; Yoshiro Okami

2004-01-01

322

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

323

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

SciTech Connect

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

Etheridge, E.L.

1993-06-10

324

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 30–60 °C. 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

325

Ice Formation by Sulfate and Sulfuric Acid Aerosol Particles under Upper-Tropospheric Conditions  

Microsoft Academic Search

Ice formation in ammoniated sulfate and sulfuric acid aerosol particles under upper-tropospheric conditions was studied using a continuous flow thermal diffusion chamber. This technique allowed for particle exposure to controlled temperatures and relative humidities for known residence times. The phase states of (NH4)2SO4 and NH4HSO4 particles were found to have important impacts on their ice formation capabilities. Dry (NH4)2SO4 particles

Yalei Chen; Paul J. Demott; Sonia M. Kreidenweis; David C. Rogers; D. Eli Sherman

2000-01-01

326

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

327

Electrochemical behavior of lead alloys in sulfuric and phosphoric acid solutions  

Microsoft Academic Search

The electrochemical behavior of lead, lead–antimony, and lead–calcium–aluminium–tin alloys has been studied in solutions containing various concentrations of sulfuric and phosphoric acids. The dependence of these electrode processes on some experimental conditions (mainly sweep rate and potential range) has been studied. The measurements were performed using a cyclic voltammetry technique. The study and the analysis of the morphology of alloys

I. Paleska; R. Pruszkowska-Drachal; J. Kotowski; A. Dziudzi; J. D. Milewski; M. Kopczyk; A. Czerwi?ski

2003-01-01

328

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

329

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

PubMed Central

Atmospheric aerosols formed by nucleation of vapors affect radiative forcing and therefore climate. However, the underlying mechanisms of nucleation remain unclear, particularly the involvement of organic compounds. Here, we present high-resolution mass spectra of ion clusters observed during new particle formation experiments performed at the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research. The experiments involved sulfuric acid vapor and different stabilizing species, including ammonia and dimethylamine, as well as oxidation products of pinanediol, a surrogate for organic vapors formed from monoterpenes. A striking resemblance is revealed between the mass spectra from the chamber experiments with oxidized organics and ambient data obtained during new particle formation events at the Hyytiälä boreal forest research station. We observe that large oxidized organic compounds, arising from the oxidation of monoterpenes, cluster directly with single sulfuric acid molecules and then form growing clusters of one to three sulfuric acid molecules plus one to four oxidized organics. Most of these organic compounds retain 10 carbon atoms, and some of them are remarkably highly oxidized (oxygen-to-carbon ratios up to 1.2). The average degree of oxygenation of the organic compounds decreases while the clusters are growing. Our measurements therefore connect oxidized organics directly, and in detail, with the very first steps of new particle formation and their growth between 1 and 2 nm in a controlled environment. Thus, they confirm that oxidized organics are involved in both the formation and growth of particles under ambient conditions. PMID:24101502

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

2013-01-01

330

EVALUATING EFFECTS OF NEPTUNIUM ON THE SRS METHOD FOR CONTROLLED POTENTIAL COULOMETRIC ASSAY OF PLUTONIUM IN SULFURIC ACID SUPPORTING ELECTROLYTE  

SciTech Connect

A study of the impact of neptunium on the coulometric assay of plutonium in dilute sulfuric acid was performed. Weight aliquots of plutonium standard solutions were spiked with purified neptunium solution to evaluate plutonium measurement performance for aliquots with Pu:Np ratios of 50:1, 30:1, 20:1, 15:1, and 10:1. Weight aliquots of the pure plutonium standard solution were measured as controls. Routine plutonium instrument control standards were also measured. The presence of neptunium in plutonium aliquots significantly increases the random uncertainty associated with the plutonium coulometric measurement performed in accordance with ISO12183:2005.7 However, the presence of neptunium does not appear to degrade electrode performance and conditioning as aliquots of pure plutonium that were interspersed during the measurement of the mixed Pu:Np aliquots continued to achieve the historical short-term random uncertainty for the method. Lack of adequate control of the neptunium oxidation state is suspected to be the primary cause of the elevated measurement uncertainty and will be pursued in a future study.

Holland, M; Sheldon Nichols, S

2008-05-09

331

Influence of Dilute Acetic Acid Treatments on American Pondweed Winter Buds in the Nevada Irrigation District, California  

Microsoft Academic Search

American pondweed ( Potamogeton nodosus Poir.) is com- monly found in northern California irrigation canals. The purpose of this study was to test the hypothesis that exposure of American pondweed winter buds to dilute acetic acid un- der field conditions would result in reduced subsequent bio- mass. The treatment consisted of adding either 1703 or 3406 L of 2.3% acetic

D. F. SPENCER; C. L. ELMORE; G. G. KSANDER; J. A. RONCORONI

332

Toxicity of nickel and silver to Nostoc muscorum: interaction with ascorbic acid, glutathione, and sulfur-containing amino acids  

SciTech Connect

Exposure of Nostoc muscorum to different concentrations of Ni and Ag brought about reduction in growth, carbon fixation, heterocyst production, and nitrogenase activity and increase in the loss of ions (K+, Na+). In an attempt to ameliorate the toxicity of test metals by ascorbic acid, glutathione, and sulfur-containing amino acids (L-cysteine and L-methionine), it was found that the level of protection by ascorbic acid and glutathione was more for Ag than Ni. However, metal-induced inhibition of growth and carbon fixation was equally ameliorated by methionine. But the level of protection by cysteine was quite different, i.e., 27% for Ni and 22% for Ag. Protection of metal toxicity in N. muscorum by amino acids lends further support to self-detoxifying ability of cyanobacteria because they are known to synthesize all essential amino acids.

Rai, L.C.; Raizada, M.

1987-08-01

333

Active/passive behavior of copper in strong sulfuric acid  

SciTech Connect

A combination of thermodynamic analyses and potentiodynamic polarization tests have been used to study the anodic behavior of Cu in strong H{sub 2}SO{sub 4} solutions in the concentration range 1--10 M. The studies were supplemented by chemical analyses of surface films. It was found that concentration-dependent changes in the activity of water played a major role in determining the anodic behavior and relative stability of corrosion product films. The anodic Tafel slope decreased from {approximately} 41 to {approximately} 31 mV with increasing acid concentration. The onset of limiting current and active-passive behaviors at higher potentials was determined by the formation of films of hydrated copper sulfate, CuSO{sub 4} {center_dot} xH{sub 2}O, and not by formation of oxides. Limiting current behavior was observed in 1 M solutions, where the degree of hydration was x = 5. Well-developed passivity occurred in 10 M solutions where x = 1. The results are relevant to industrial electrorefining operations for Cu and indicate that chloride contamination, if present in sufficient amounts, could cause the premature onset of limiting current behavior (anode passivity) during refining.

Tromans, D.; Ahmed, T. [Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Metals and Materials Engineering

1998-02-01

334

Quantification of human growth hormone by amino acid composition analysis using isotope dilution liquid-chromatography tandem mass spectrometry  

Microsoft Academic Search

We describe an accurate method for protein quantification based on conventional acid hydrolysis and an isotope dilution–HPLC–mass spectrometry (ID–HPLC–MS) method. Sample purity was confirmed using capillary zone electrophoresis, HPLC and MS. The analyte protein, human growth hormone (hGH), was effectively hydrolyzed by incubation with 8M hydrochloric acid at 130°C for 48h, where at least 1?M of hGH was treated to

Ji-Seon Jeong; Hyuk-Min Lim; Sook-Kyung Kim; Hyung-Keun Ku; Kyung-Hwa Oh; Sang-Ryoul Park

2011-01-01

335

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

SciTech Connect

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

Frederick F. Stewart; Christopher J. Orme

2006-11-01

336

Effect of lime on the availability of residual phosphorus and its extractability by dilute acid  

SciTech Connect

The objective of this study was to determine the long-term effects of liming an acid, P-deficient Placid sand (sandy, siliceous, hyperthermic Typic Humaquept) on the availability of residual fertilizer P to potatoes (Solanum tuberosum L.). Dolomitic limestone was applied in November 1977, at rates of 0, 2240, 4480, and 8960 kg/ha in a split-plot design with lime as main plots and P treatments as subplots. Phosphorus was applied at rates of 0, 56, 112, and 168 kg/ha in 1978. In 1979 and 1980, P plots were split with one-half fertilized with 56 kg P/ha and the other one-half not fertilized with P (residual). In 1978, maximum tuber yields and top dry weights occurred at the 2240 kg/ha lime rate which resulted in a soil pH of 5.8. Plant P concentrations were unaffected by lime at any sampling rate. In 1979, availability of residual soil P decreased with lime rates > 2240 kg/ha but not enough to significantly affect yields. However, in 1980, overliming injury was observed for tuber yields at the higher lime rates which was the result of P deficiency. Application of P at planting eliminated the overliming injury with maximum yields occurring in the pH range of 6.0 to 6.5. It appears that liming to pH 6.5 in this study resulted in fertilizer reaction products that were more soluble in dilute acid but less plant available than those formed under more acid conditions. However, the Mehlich I extractant appeared to be a suitable extractant for P on this soil if pH was taken into account when interpreting soil-test P. 23 references, 4 figures, 2 tables.

Rhue, R.D.; Hensel, D.R.

1983-01-01

337

Production of fuel ethanol from bamboo by concentrated sulfuric acid hydrolysis followed by continuous ethanol fermentation.  

PubMed

An efficient process for the production of fuel ethanol from bamboo that consisted of hydrolysis with concentrated sulfuric acid, removal of color compounds, separation of acid and sugar, hydrolysis of oligosaccharides and subsequent continuous ethanol fermentation was developed. The highest sugar recovery efficiency was 81.6% when concentrated sulfuric acid hydrolysis was carried out under the optimum conditions. Continuous separation of acid from the saccharified liquid after removal of color compounds with activated carbon was conducted using an improved simulated moving bed (ISMB) system, and 98.4% of sugar and 90.5% of acid were recovered. After oligosaccharide hydrolysis and pH adjustment, the unsterilized saccharified liquid was subjected to continuous ethanol fermentation using Saccharomycescerevisiae strain KF-7. The ethanol concentration, the fermentation yield based on glucose and the ethanol productivity were approximately 27.2 g/l, 92.0% and 8.2 g/l/h, respectively. These results suggest that the process is effective for production of fuel ethanol from bamboo. PMID:21974887

Sun, Zhao-Yong; Tang, Yue-Qin; Iwanaga, Tomohiro; Sho, Tomohiro; Kida, Kenji

2011-12-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

339

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

340

Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere - Abundances inferred from observed radio opacity  

NASA Technical Reports Server (NTRS)

It is suggested that the absorbing characteristics of sulfuric acid vapor appear to reconcile what had been thought to be an inconsistency among measurements and deductions regarding the constituents of the Venus atmosphere and radio occultation, radar reflection, and radio emission measurements of its opacity. Laboratory measurements of sulfuric acid, sulfur dioxide, water vapor, and carbon dioxide are used to model relative contributions to opacity as a function of height in a way that is consistent with observations of the constituents and absorbing properties of the atmosphere. It is concluded that sulfuric acid vapor is likely to be the principal microwave absorber in the 30-50 km altitude range of the middle atmosphere of Venus.

Steffes, P. G.; Eshleman, V. R.

1982-01-01

341

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

SciTech Connect

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

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

1980-10-01

342

MELCOR-H2 Benchmarking of the SNL Transient Sulfuric Acid Decomposition Experiments  

SciTech Connect

MELCOR is a world-renowned nuclear reactor safety analysis code that is used to simulate both light water and gas-cooled reactors. MELCOR-H2 is an extension of MELCOR that can model detailed nuclear reactors that are fully coupled with modular secondary-system components and the sulfur iodine (SI) thermochemical cycle for the generation of hydrogen and electricity. The models are applicable to both steady state and transient calculations. Previous work has shown that the hydrogen generation rate calculated by MELCOR-H2 for the SI cycle was within the expected theoretical yield, thus providing a macroscopic confirmation that MELCOR-H2's computational approach is reasonable. However, in order to better quantify its adequacy, benchmarking of the code with experimental data is required. Sulfuric acid decomposition experiments were conducted during late 2006 at Sandia National Laboratories, and MELCOR-H2 was used to simulate them. We developed an input deck based on the experiment's geometry, as well as the initial and boundary conditions, and then proceeded to compare the experimental acid conversion efficiency and SO{sub 2} production data with the code output. The comparison showed that the simulation output was typically within less than 10% of experimental data, and that key experimental data trends such as acid conversion efficiency, molar acid flow rate, and solution mole % were computed adequately by the MELCOR-H2. (authors)

Rodriguez, Sal B.; Gauntt, Randall O.; Gelbard, Fred; Pickard, Paul; Cole, Randy; McFadden, Katherine; Drennen, Tom; Martin, Billy [Sandia National Laboratories, P.O. Box 5800, MS 0748, Albuquerque, NM 87185-0748 (United States); Louie, David; Archuleta, Louis [OMICRON Safety and Risk (United States); Revankar, Shripad T. [Purdue University (United States); Vierow, Karen [University of Texas A and M (United States); El-Genk, Mohamed; Tournier, Jean Michel [University of New Mexico (United States)

2007-07-01

343

The infrared optical constants of sulfuric acid at 250 K. [spectral reflectance measurement of aqueous solutions  

NASA Technical Reports Server (NTRS)

Results are presented for measurements of the IR spectral reflectance at near-normal incidence of aqueous solutions of sulfuric acid with acid concentrations of 75% and 95.6% by weight. Kramers-Kronig analyses of the reflectance data are employed to obtain values of the optical constants n(nu) and k(nu) in the spectral range from 400 to 6000 cm to the -1 power. The optical constants of these solutions at 250 K and 300 K are compared. It is found that in spectral regions remote from strong absorption bands, the values of the n(nu) indices obtained at 250 K agree with the values given by Lorentz-Lorenz correction of the same indices at 300 K. All absorption bands observed at 300 K are found to be present at 250 K with slight shifts in frequency and with significant differences in the k(nu) indices at the band maxima. Based on these results, it is concluded that the clouds of Venus probably consist of droplets of aqueous solutions of sulfuric acid with acid concentrations of about 75% by weight.

Pinkley, L. W.; Williams, D.

1976-01-01

344

Effects of sulfuric acid rain on two model hardwood forests: throughfall, litter leachate, and soil solution  

SciTech Connect

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 chemistry, the litter leachate (the actual input to the soil) had consistently higher concentrations of calcium and magnesium, and higher pH than the acid rain. For the first 6 months, sulfate absorption by the soil prevented any apparent differences in sulfate, calcium, or magnesium concentrations in the 20-cm soil solution among plots receiving acid or control rain treatments. Sulfate concentrations on plots receiving the most acid rain (pH 3.0) then became increasingly higher than on the other plots until after 3 years, they were approximately equal to sulfate concentrations in the rain. Twenty-cm soil solutions corresponding to the pH 3.5 and 4.0 treatments responded similarly starting respectively 1 year and 2 years after initiation of exposure to acid rain. Increased calcium and magnesium concentrations and lowered pH in 20-cm soil solution occurred simultaneously with increased sulfate concentrations. No acid rain related effects were evident in the 1-m soil solution even after 3.5 years exposure to pH 3.0 sulfuric acid rain. Cation responses to increased anion concentrations followed those predicted by a computer-simulation model. However, sulfate concentrations in 20-cm soil solutions increased considerably faster than predicted by a Langmuir formulation of sulfate absorption.

Lee, J.J.; Weber, D.E.

1980-01-01

345

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

PubMed

Sulfur mustard (SM) is a classic vesicant agent, which has been greatly employed in several wars or military conflicts. The most lesion mechanism is its strong alkylation of DNAs in vivo. Until now there are four specific DNA adducts of SM identified for further retrospective detection, i.e., N(7)-(2-hydroxyethylthioethyl)-2'-guanine (N(7)-HETEG), bis(2-ethyl-N(7)-guanine)thioether (Bis-G), N(3)-(2-hydroxyethylthioethyl)-2'-adenine (N(3)-HETEA) and O(6)-(2-hydroxyethylthioethyl)-2'-guanine (O(6)-HETEG), respectively. Here, a novel and sensitive method of isotope-dilution ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combining with solid phase extraction was reported for the simultaneous determination of four SM-DNA adducts. A lower limit of detection of 2-5ngL(-1), and a lower limit of quantitation of 5-10ngL(-1) were achieved, respectively, and the recoveries ranged from 87% to 116%. We applied this method in the determination of four SM-DNA adducts in rabbit urine after dermal exposure by SM in three dose levels (2, 5, 15mgkg(-1)), so as to investigate the related metabolic behavior in vivo. For the first time, in SM exposed rabbit urine, our results revealed the relative accumulation abundance of four SM-DNA adducts, i.e., 67.4% for N(7)-HETEG, 22.7% for Bis-G, 9.8% for N(3)-HETEA, 0.1% for O(6)-HETEG, and significant dose and time dependent responses of these SM-DNA adducts. The four adducts were detectable after 8h, afterwards, their contents continuously increased, achieved maximum in the first two or three days and then gradually decreased till the end of one month. Meanwhile, the amounts of SM-DNA adducts were positively correlated with the exposure doses. PMID:24858262

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

2014-06-15

346

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

347

Respiratory responses of exercising asthmatic volunteers exposed to sulfuric acid aerosol  

SciTech Connect

Young asthmatic adult volunteers (N = 27) were exposed in an environmental chamber to sulfuric acid aerosol at concentrations near 0, 122, 242, and 410 ..mu..g/m/sup 3/, in purified background air at 22/sup 0/C and 50 percent relative humidity. The polydisperse aerosol had a mass median aerodynamic diameter near 0.6 ..mu..m. Exposures occurred in random order at one-week intervals. Each lasted 1 h, during which subjects exercised (mean ventilation 42 L/min) and rested during alternate 10-min periods. Specific airway resistance and forced expiratory function were measured pre-exposure, after the initial exercise, and at end-exposure. Bronchial reactivity was determined by challenge with cold air immediately post-exposure. Symptoms were monitored during exposure for one week afterward. Exercise-induced bronchospasm was observed under all conditions. Physiologic and symptom changes possibly attributable to sulfuric acid exposure were small and not statistically significant. Our largely negative results contrast with positive findings elsewhere at lower acid doses. Possible explanations include different clinical characteristics of subjects and different routes of breathing.

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

1986-12-01

348

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

349

Alpha-amylase production is induced by sulfuric acid in rice aleurone cells.  

PubMed

The hydrolytic enzyme alpha-amylase (EC 3.2.1.1) is produced mainly in aleurone cells of germinating cereals, and the phytohormone gibberellin (GA) is essential for its induction. However, in rice (Oryza sativa L.), sulfuric acid (H(2)SO(4)) induces alpha-amylase production in aleurone tissue even in the absence of GA. Here, the pre-treatment of rice aleurone cells with H(2)SO(4) and incubation in water induced alpha-amylase activity, as if the cells had been incubated in GA solution. PMID:17988885

Mitsunaga, Shin-ichiro; Kobayashi, Midori; Fukui, Satoe; Fukuoka, Kayoko; Kawakami, Osamu; Yamaguchi, Junji; Ohshima, Masahiro; Mitsui, Toshiaki

2007-12-01

350

The development of nickel silicide based alloy for sulfuric acid application  

NASA Astrophysics Data System (ADS)

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

Zhang, Sanhong

2000-10-01

351

Combined Dilute Acid and Solvent Based Pretreatment of Agricultural Wastes for Efficient Lignocellulosic Fractionation and Biofuels Production  

SciTech Connect

A true biorefinery for processing lignocellulosic biomass should achieve maximum utilization of all major constituents (cellulose, hemicellulose, & lignin) within the feedstock. In this work a combined pretreatment process of dilute acid (DA) and N-methyl morpholine N-oxide (NMMO) is described that allows for both fractionation and subsequent complete hydrolysis of the feedstocks (corn stover and sugarcane bagasse). During this multi-step processing, the dilute acid pretreatment solubilizes the majority (>90%) of the hemicellulosic fraction, while the NMMO treatment yields a cellulosic fraction that is completely digestible within 48 hours at low enzyme loadings. With both the cellulosic and hemicellulosic fractions being converted into separate, dissolved sugar fractions, the remaining portion is nearly pure lignin. When used independently, DA and NMMO pretreatments are only able to achieve ~80% and ~45% cellulosic conversion, respectively. Mass balance calculations along with experimental results are used to illustrate the feasibility of separation and recycling of NMMO.

Brodeur, G.; Ramakrishnan, S.; Wilson, C.; Telotte, J.; Collier, J.; Stickel, J.

2013-01-01

352

Inorganic Aerosols and Their Role in Catalyzing Sulfuric Acid Production in Furnaces  

Microsoft Academic Search

Submicrometer ash and sulfur oxides are important pollutants formed during pulverized coal combustion. The submicrometer ash contains known catalysts for sulfur dioxide oxidation as well as alkaline species that will react with sulfur oxides. This work was an investigation to determine if submicrometer ash-sulfur oxide interactions can have a significant impact on the fate of sulfur.The submicrometer-ash-sulfur oxide interaction studies

Karl A. Graham; Adel F. Sarofim

1998-01-01

353

Enthalpies of Dilution and Enthalpies of Mixing of Amino Acids with Sucrose in Aqueous Solutions at 298.15 K  

Microsoft Academic Search

The enthalpies of mixing of aqueous solutions have been determined for sucrose with six different amino acids (glycine, l-alanine, l-serine, l-valine, l-proline and l-threonine) at 298.15 K, by using a LKB-2277 flow microcalorimetric system. These results, along with the enthalpies of dilution of these solutes for the initial solutions, were used to determine the enthalpic interaction coefficients (h\\u000a xy, h

Huaji Liu; Ruisen Lin; Honglin Zhang

2006-01-01

354

Effects of sulfuric acid rain on major cation and sulfate concentrations of water percolating throught two model hardwood forests  

Microsoft Academic Search

To document and quantify ecosystem response to the onset of acid precipitation, simulated sulfuric acid (HâSOâ) rain was applied to model forest plots of sugar maple (Acer saccharum Marsh.) and red alder (Alnus rubra Bong.) One set of four plots (two alder and two maple) received a control rain consisting of a stock solution equilibrated with atmospheric COâ to approximately

J. J. Lee; D. E. Weber

2009-01-01

355

Glucose content in the liquid hydrolysate after dilute acid pretreatment is affected by the starch content in rice straw.  

PubMed

Lignocellulosic biomass, such as rice straw, is often utilized as a bioresource after being hydrolyzed using dilute acid and separated into liquid hydrolysate and acid-insoluble residue. However, the biomass component that determines the distribution between liquid hydrolysate and acid-insoluble residue has not yet been clarified. In this study, the glucose content in the liquid hydrolysate and weight of acid-insoluble residue of 13 rice cultivars were analyzed. Starch content was positively correlated with glucose content in the liquid hydrolysate, and negatively correlated with acid-insoluble residue weight. These results indicate that the glucose in the liquid hydrolysate is mainly liberated from starch rather than cellulose in the rice straw. These observations suggest that starch content is a good indicator of the glucose distribution between the liquid hydrolysate and insoluble residue. PMID:24140898

Teramura, Hiroshi; Oshima, Tomoko; Matsuda, Fumio; Sasaki, Kengo; Ogino, Chiaki; Yamasaki, Masanori; Kondo, Akihiko

2013-12-01

356

Multifaceted characterization of cell wall decomposition products formed during ammonia fiber expansion (AFEX) and dilute acid based pretreatments.  

PubMed

Decomposition products formed/released during ammonia fiber expansion (AFEX) and dilute acid (DA) pretreatment of corn stover (CS) were quantified using robust mass spectrometry based analytical platforms. Ammonolytic cleavage of cell wall ester linkages during AFEX resulted in the formation of acetamide (25mg/g AFEX CS) and various phenolic amides (15mg/g AFEX CS) that are effective nutrients for downstream fermentation. After ammonolysis, Maillard reactions with carbonyl-containing intermediates represent the second largest sink for ammonia during AFEX. On the other hand, several carboxylic acids were formed (e.g. 35mg acetic acid/g DA CS) during DA pretreatment. Formation of furans was 36-fold lower for AFEX compared to DA treatment; while carboxylic acids (e.g. lactic and succinic acids) yield was 100-1000-fold lower during AFEX compared to previous reports using sodium hydroxide as pretreatment reagent. PMID:20598525

Chundawat, Shishir P S; Vismeh, Ramin; Sharma, Lekh N; Humpula, James F; da Costa Sousa, Leonardo; Chambliss, C Kevin; Jones, A Daniel; Balan, Venkatesh; Dale, Bruce E

2010-11-01

357

Catalytic Activity of Supported Metal Particles for Sulfuric Acid Decomposition Reaction  

SciTech Connect

Production of hydrogen by splitting water in thermochemical water-splitting cycles, such as the sulfur-based group that employs the catalytic decomposition of sulfuric acid into SO2 and O2 is of considerable interest. Most of these processes occur at high temperatures (T = 1,000 K) and exposes catalysts to the extreme conditions such as steam, oxygen, and acid vapor that severely damage these catalysts within a short time. To develop an understanding of the factors that cause catalyst deactivation, we performed density-functional-theory (DFT)-based first-principles calculations and computer simulations for transition metal (TM) particles positioned on the two types of substrate (?-alumina and TiO2-rutile). The catalytic activity of the considered systems is defined by several factors, namely: (i) The efficiency of detaching oxygen atoms from the sulfur-containing species SOn (n = 1,2,3). The breaking of the S-O bonds may occur at both the substrate and the transition metal cluster. However, the bond-breaking at the substrate is endothermic (and takes about 1.5 eV per bond) while at low-coordinated metal atom of a cluster it is exothermic (with energy gain of about 0.5 eV per bond). This explains why the presence of transition metal clusters is necessary for catalytic activity; (ii) The ability of the cluster to “clean” itself, i.e., to eliminate oxygen from its surface, in order to regain the catalytically active sites and to continue the process. We found that the clusters of Pd and Pt with the size = 2-3 nm are more efficient in this process (at T = 1,000 K) than the clusters of other TM’s considered (Rh, Ir, Ru, and Os); (iii) The ability of the cluster to keep its size to avoid sintering (that reduces the number of low-coordinated catalytically active sites at the surface of the cluster). We found that the sintering of Rh, Ir, Ru, and Os clusters is significantly suppressed in comparison with the sintering of Pd and Pt clusters of the same size (the individual atoms at the surface of Rh and Ir clusters have a tendency to have higher coordination number, i.e., the detachment of individual atoms from the surface is less likely). Therefore, the activity of TM nanoparticles is mainly defined by the competing factors (ii) and (iii). At the present, we try to find (experimentally and theoretically) the most optimal combination of the structure, size, and composition of TM nanoparticles, for which the catalytic activity of sulfuric acid decomposition will be the highest.

Sergey N. Rashkeev; Daniel M. Ginosar; Lucia M. Petkovic; Helen H. Farrell

2007-08-01

358

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

359

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

PubMed Central

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

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

2014-01-01

360

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

SciTech Connect

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

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

2006-01-01

361

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

PubMed

Dilute sulfuric acid pretreated corn stover is potential feedstock of industrial interest for second generation fuel ethanol production. However, the toxicity of corn stover hydrolysate (PCS) has been a challenge for fermentation by recombinant xylose 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 immobilized reactor system at 70 degrees C. The tested strain showed significant resistance to PCS, and substrate concentrations up to 15% total solids (TS) were fermented yielding ethanol of 0.39-0.42 g/g-sugars consumed. Xylose was nearly completely utilized (89-98%) for PCS up to 10% TS, whereas at 15% TS, xylose conversion was lowered to 67%. The reactor was operated continuously for 135 days, and no contamination was seen without the use of any agent for preventing bacterial infections. This study demonstrated that the use of immobilized thermophilic anaerobic bacteria for continuous ethanol fermentation could be promising in a commercial ethanol process in terms of system stability to process hardiness and reactor contamination. The tested microorganism has considerable potential to be a novel candidate for lignocellulose bioconversion into ethanol. PMID:17899073

Georgieva, Tania I; Ahring, Birgitte K

2007-11-01

362

Co-hydrolysis of hydrothermal and dilute acid pretreated populus slurries to support development of a high-throughput pretreatment system  

PubMed Central

Background The BioEnergy Science Center (BESC) developed a high-throughput screening method to rapidly identify low-recalcitrance biomass variants. Because the customary separation and analysis of liquid and solids between pretreatment and enzymatic hydrolysis used in conventional analyses is slow, labor-intensive and very difficult to automate, a streamlined approach we term 'co-hydrolysis' was developed. In this method, the solids and liquid in the pretreated biomass slurry are not separated, but instead hydrolysis is performed by adding enzymes to the whole pretreated slurry. The effects of pretreatment method, severity and solids loading on co-hydrolysis performance were investigated. Results For hydrothermal pretreatment at solids concentrations of 0.5 to 2%, high enzyme protein loadings of about 100 mg/g of substrate (glucan plus xylan) in the original poplar wood achieved glucose and xylose yields for co-hydrolysis that were comparable with those for washed solids. In addition, although poplar wood sugar yields from co-hydrolysis at 2% solids concentrations fell short of those from hydrolysis of washed solids after dilute sulfuric acid pretreatment even at high enzyme loadings, pretreatment at 0.5% solids concentrations resulted in similar yields for all but the lowest enzyme loading. Conclusions Overall, the influence of severity on susceptibility of pretreated substrates to enzymatic hydrolysis was clearly discernable, showing co-hydrolysis to be a viable approach for identifying plant-pretreatment-enzyme combinations with substantial advantages for sugar production. PMID:21749707

2011-01-01

363

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

SciTech Connect

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

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

1980-06-01

364

Studies on the protein and sulfur amino acid requirements of young bobwhite quail  

USGS Publications Warehouse

Four experiments were conducted with purified diets to examine the influence of protein level and to estimate the sulfur amino acid (S.A.A.) requirement of young Bobwhite quail (Colinus virginianus). These studies demonstrated (I) that 26% protein was sufficient for rapid growth when the diet was supplemented with methionine; (2) that diets containing higher levels of protein (29.3% and 31.3%) failed to support satisfactory growth unless they contained supplemental methionine; and (3) that young Bobwhite quail require no more than 1.0% sulfur-containing amino acids for optimal growth and efficiency of feed utilization. A fifth experiment was conducted to examine the protein and S.A.A. requirements of young Bobwhite quail using practical rations and to compare results with those obtained with purified diets. Diets containing 24%, 26% and 28% protein were supplied with and without supplemental methionine in a five week study. Results showed significant growth responses to protein and supplemental methionine. Responses showed that Bobwhite quail require no more than 26% protein for maximum growth and efficiency of feed utilization when the S.A.A. level of the diet was approximately 1.0%. The results were in close agreement with those obtained with purified diets. These findings define more precisely than had been known the quantitative requirements of young Bobwhite quail for protein and for the S.A.A. necessary for optimal growth.

Serafin, J.A.

1977-01-01

365

Ice Formation by Sulfate and Sulfuric Acid Aerosol Particles under Upper-Tropospheric Conditions.  

NASA Astrophysics Data System (ADS)

Ice formation in ammoniated sulfate and sulfuric acid aerosol particles under upper-tropospheric conditions was studied using a continuous flow thermal diffusion chamber. This technique allowed for particle exposure to controlled temperatures and relative humidities for known residence times. The phase states of (NH4)2SO4 and NH4HSO4 particles were found to have important impacts on their ice formation capabilities. Dry (NH4)2SO4 particles nucleated ice only at high relative humidity (RH 94%) with respect to water at temperatures between 40° and 60°C. This result suggested either an impedance or finite time dependence to deliquescence and subsequent homogeneous freezing nucleation. Ammonium sulfate particles that entered the diffusion chamber in a liquid state froze homogeneously at relative humidities that were 10% lower than where ice nucleated on initially dry particles. Likewise, crystalline or partially crystallized (as letovicite) NH4HSO4 particles required higher relative humidities for ice nucleation than did initially liquid bisulfate particles. Liquid particles of size 0.2 m composed of either ammonium sulfate or bisulfate froze at lower relative humidity at upper-tropospheric temperatures than did 0.05-m sulfuric acid aerosol particles. Comparison of calculated homogeneous freezing point depressions suggest that size effects on freezing may be more important than the degree of ammoniation of the sulfate compound.

Chen, Yalei; Demott, Paul J.; Kreidenweis, Sonia M.; Rogers, David C.; Eli Sherman, D.

2000-11-01

366

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

367

Enhanced acid rain and atmospheric deposition of nitrogen, sulfur and heavy metals in Northern China  

NASA Astrophysics Data System (ADS)

Atmospheric deposition is known to be important mechanism reducing air pollution. In response to the growing concern on the potential effects of the deposited material entering terrestrial and aquatic environments as well as their subsequent health effects, since 2007 we have established a 10-site monitoring network in Northern China, where particularly susceptible to severe air pollution. Wet and dry deposition was collected using an automatic wet-dry sampler. The presentation will focus on the new results of atmospheric deposition flux for a number of chemical species, such as nutrients (e.g. nitrogen and phosphorus), acidic matters (e.g. sulfur and proton), heavy metals and Polycyclic Aromatic Hydrocarbons, etc. This is to our knowledge the first detailed element budget study in the atmosphere across Northern China. We find that: (1) Over the 3 year period, 26% of precipitation events in the target area were more acid than pH 5.60 and these acidic events occurred in summer and autumn. The annual volume-weighted mean (VWM) pH value of precipitation was lower than 5.60 at most sites, which indicated the acidification of precipitation was not optimistic. The primary ions in precipitation were NH4+, Ca2+, SO42- and NO3-, with 10-sites-average concentrations of 221, 216, 216 and 80 ?eq L-1, respectively. The ratio of SO42- to NO3- was 2.7; suggesting SO42- was the dominant acid component. (2) The deposited particles were neutral in general and the pH value increased from rural area to industrial and coastal sites. It is not surprising to note that the annual VWM pH value of precipitation was higher than 5.60 at three urban sites (Beijing and Tianjin mega cities) and one coastal site near the Bohai Bay, considering the fact that high buffer capacity of alkaline component, gas NH3 and mineral aerosols, at these sites compared to other places. (3) The 10-sites annual total deposition amounts for sulfur and nitrogen compounds were 60 and 65 kg N/S ha-1 yr-1, respectively. Total deposition amounts of sulfur and nitrogen in North China were 5-10 times higher than those in CASTNet and EMEP, as well as EANET sites in Japan, which indicated that the increasing emissions of air pollutants in North China resulted in high atmospheric depositions. Integrated assessment of acidic and toxic deposition and potential environmental consequences in North China are highly needed.

Pan, Y.; Wang, Y.

2013-12-01

368

Freshwater acidification from atmospheric deposition of sulfuric acid: a conceptual model  

SciTech Connect

A simple conceptual model is presented that incorporates only a few key processes which are felt to determine how aquatic ecosystems respond to acid deposition with respect to time. The model is based on the assumption that if the rate of acid deposition changes, a variety of constituents in both the terrestrial and aquatic systems will respond. The model has seven stages: preacidification stage - steady state prior to significant emissions or anthropogenic sulfur; undersaturated sulfate adsorption capacity; saturated sulfate adsorption capacity in soil; steady-state period of lake acidification; supersaturated sulfate adsorption capacity; recovery of the percent base saturation; and the stable period of lake recovery. The model can be used by defining the pertinent characteristics of each stage and identifying geographical regions that have those characteristics. 19 references, 2 figures.

Galloway, J.N.; Norton, S.A.; Church, M.R.

1983-11-01

369

POTENTIAL PRODUCTION AND MARKETING OF FGD BYPRODUCT SULFUR AND SULFURIC ACID IN THE U.S. (1983 PROJECTION)  

EPA Science Inventory

The report updates to 1983 a 1978-base, computerized marketing evaluation of sulfur and H2SO4 as flue gas desulfurization (FGD) byproducts from U.S. coal-burning power plants. Least-costs of compliance were calculated using comparisons of clean fuel with 50 cents and 70 cents/mil...

370

Effects of fly ash and silica fume on the resistance of mortar to sulfuric acid and sulfate attack  

SciTech Connect

Changes in physical and chemical properties in the mortars with different replacements by fly ash and silica fume when immersed in 2 % H[sub 2]SO[sub 4], 10 % Na[sub 2]SO[sub 4] and 10% MgSO[sub 4] solutions for 3 years were investigated. The long-term exposure test data showed that the replacement of portland cement by fly ash and silica fume effectively improved the resistance of the mortar to the sulfuric acid and sulfate solution attack. However, the replacement percentage by fly ash and silica fume necessary to prevent the sulfuric acid and sulfate solution attack varied significantly depending on the type of sulfuric acid and sulfate solutions.

Torii, Kazuyuki; Kawamura, Mitsunori (Kanazawa Univ. (Japan). Dept. of Civil Engineering)

1994-01-01

371

Sulfuric Acid Hydrolysis and Detoxification of Red Alga Pterocladiella capillacea for Bioethanol Fermentation with Thermotolerant Yeast Kluyveromyces marxianus.  

PubMed

One-step sulfuric acid saccharification of the red alga Pterocladiella capillacea was optimized, and various detoxification methods (neutralization, overliming, and electrodialysis) of the acid hydrolysate were evaluated for fermentation with the thermotolerant yeast Kluyveromyces marxianus. A proximate composition analysis indicated that P. capillacea was rich in carbohydrates. A significant galactose recovery of 81.1 ± 5% was also achieved under the conditions of a 12% (w/v) biomass load, 5% (v/v) sulfuric acid, 121°C, and hydrolysis for 30 min. Among the various detoxification methods, electrodialysis was identified as the most suitable for fermentable sugar recovery and organic acid removal (100% reduction of formic and levulinic acids), even though it failed to reduce the amount of the inhibitor 5-HMF. As a result, K. marxianus fermentation with the electrodialyzed acid hydrolysate of P. capillacea resulted in the best ethanol levels and fermentation efficiency. PMID:24851812

Wu, Chien-Hui; Chien, Wei-Chen; Chou, Han-Kai; Yang, Jungwoo; Lin, Hong-Ting Victor

2014-09-28

372

Evidence for Incorporation of H2S in Groundwater Fulvic Acids from Stable Isotope Ratios and Sulfur K-edge X-ray Absorption Near Edge Structure Spectroscopy  

SciTech Connect

Groundwater samples collected in a shallow oxic and reduced deep groundwater system revealed the influence of dissolved sulfide on the chemical and isotopic composition of fulvic acid associated sulfur. Stable isotope compositions of groundwater sulfate and fulvic acid sulfur and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy data were used to determine the sources and processes affecting fulvic acid sulfur in the aquifer. A {delta}34S value of 2.2 %% for the shallow groundwater sulfate and a {delta}34S value of fulvic acids of 4.9 % accompanied by a contribution of up to 49% of the most oxidized sulfur species (S+6) documented that fulvic acid sulfur is mainly derived from soil S compounds such as ester sulfates, with {delta}34S values similar to those of atmospheric sulfate deposition. In contrast, in the deep groundwater system with elevated {delta}34S values in groundwater sulfate of up to 20% due to bacterial sulfate reduction, {delta}34S values in fulvic acid sulfur were negative and were up to 22% lower compared to those of groundwater sulfate. Furthermore, reduced sulfur compounds constituted a significantly higher proportion of total fulvic acid sulfur in the deep groundwater compared to fulvic acids in shallow groundwater, supporting the hypothesis that fulvic acids act as a sink for dissolved hydrogen sulfide in the deep aquifer. Our results suggest that the combination of sulfur K edge XANES spectroscopy and stable isotope analysis on fulvic acids represents a powerful tool to elucidate the role of fulvic acids in the sulfur cycle in groundwater.

Einsiedl,F.; Mayer, B.; Schäfer, T.

2008-01-01

373

Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid  

NASA Astrophysics Data System (ADS)

Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

Deng, Bo; Yu, Yang; Zhang, Bowu; Yang, Xuanxuan; Li, Linfan; Yu, Ming; Li, Jingye

2011-02-01

374

Furfural Production from Fruit Shells by Acid-Catalyzed Hydrolysis  

Microsoft Academic Search

Pentosans are hydrolyzed to pentoses by dilute mineral acid hydrolysis. The main source of pentosans is hemicelluloses. Furfural can be produced by the acid hydrolysis of pentosan from fruit shells such as hazelnut, sunflower, walnut, and almond of agricultural wastes. Further dehydration reactions of the pentoses yield furfural. The hydrolysis of each shell sample was carried out in dilute sulfuric

Ayhan Demirbas

2006-01-01

375

Acid-catalyzed reactions of hexanal on sulfuric acid particles: Identification of reaction products  

Microsoft Academic Search

While it is well established that organics compose a large fraction of the atmospheric aerosol mass, the mechanisms through which organics are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds with carbonyl groups have recently been suggested as important pathways for transfer of volatile organics into acidic aerosols. In the present study, we use the aerodyne

Rebecca M. Garland; Matthew J. Elrod; Kristi Kincaid; Melinda R. Beaver; Jose L. Jimenez; Margaret A. Tolbert

2006-01-01

376

Characterization of acid river dilution and associated trace element behavior through hydrogeochemical modeling: A case study of the Banyu Pahit River  

E-print Network

and Matschullat, 2006). A combination of these processes is at work in the case of acid mine drainage, whereCharacterization of acid river dilution and associated trace element behavior through-(oxy)hydroxide upon entering the acid water. Subsequent satu- ration in Fe-(oxy)hydroxide after mixing

McKenzie, Jeffrey M.

377

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

Microsoft Academic Search

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

Hiroshi Fukui; Isao Minatsuki; Kazuo Ishino

2006-01-01

378

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

Microsoft Academic Search

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

Isao Minatsuki; Hiroshi Fukui; Kazuo Ishino

2007-01-01

379

Electrodialysis of Sulfuric Acid with Cation-Exchange Membranes Prepared by Electron-Beam-Induced Graft Polymerization  

NASA Astrophysics Data System (ADS)

Strongly acidic cation-exchange membranes were prepared by the electron-beam-induced graft polymerization of glycidyl methacrylate onto a high-density polyethylene film with a thickness of 35 ?m and the subsequent conversion of the resulting epoxy group into a sulfonic acid group. The resulting cation-exchange membranes with various ion-exchange capacities or sulfonic acid group densities ranging from 1.9 to 2.7 mmol/g were applied to the enrichment of 0.50 mol/L sulfuric acid by electrodialysis. Concentrated sulfuric acids at concentrations of 1.4 to 2.9 mol/L were obtained in the concentrate chamber during the electrodialysis operated at 30 mA/cm2 and 298 K, using a pair of this cation-exchange membrane and a commercially available anion-exchange membrane.

Asari, Yuki; Shoji, Nobuyoshi; Miyoshi, Kazuyoshi; Umeno, Daisuke; Saito, Kyoichi

380

Lewis acid-base interactions between polysulfides and metal organic framework in lithium sulfur batteries.  

PubMed

Lithium-sulfur (Li-S) battery is one of the most promising energy storage systems because of its high specific capacity of 1675 mAh g(-1) based on sulfur. However, the rapid capacity degradation, mainly caused by polysulfide dissolution, remains a significant challenge prior to practical applications. This work demonstrates that a novel Ni-based metal organic framework (Ni-MOF), Ni6(BTB)4(BP)3 (BTB = benzene-1,3,5-tribenzoate and BP = 4,4'-bipyridyl), can remarkably immobilize polysulfides within the cathode structure through physical and chemical interactions at molecular level. The capacity retention achieves up to 89% after 100 cycles at 0.1 C. The excellent performance is attributed to the synergistic effects of the interwoven mesopores (?2.8 nm) and micropores (?1.4 nm) of Ni-MOF, which first provide an ideal matrix to confine polysulfides, and the strong interactions between Lewis acidic Ni(II) center and the polysulfide base, which significantly slow down the migration of soluble polysulfides out of the pores, leading to the excellent cycling performance of Ni-MOF/S composite. PMID:24702610

Zheng, Jianming; Tian, Jian; Wu, Dangxin; Gu, Meng; Xu, Wu; Wang, Chongmin; Gao, Fei; Engelhard, Mark H; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

2014-05-14

381

The effects of inhaled sulfuric acid on pulmonary function in adolescent asthmatics  

SciTech Connect

Ten adolescent subjects with extrinsic asthma and exercise-induced bronchospasm were studied. The subjects were exposed for 30 min at rest followed by 10 min during moderate exercise on a treadmill to either 100 micrograms/m3 sodium chloride (NaCl) or 100 micrograms/m3 sulfuric acid (H/sub 2/SO/sub 4/) droplet aerosols. All exposures were at approximately 75% relative humidity and 22 degrees C. Pulmonary functional measurements were recorded before, during, and after exposure while the subject was seated in a body plethysmograph. Exposure to the NaCl aerosol during exercise produced a small (12%) but significant drop in maximal expiratory flow (V/sub max/75) (p less than 0.05). However, exposure to the H/sub 2/SO/sub 4/ aerosol produced larger reductions in V/sub max/75 (29%; p less than 0.01) and also significant changes in 3 other parameters of pulmonary function: V/sub max/50, FEV1, and total respiratory resistance (RT). The changes were similar to those reported for exposure to 0.5 ppm of sulfur dioxide in a similar group of adolescents with extrinsic asthma. Our results are the first report of reversible pulmonary functional changes after H/sub 2/SO/sub 4/ exposure in a group of adolescent asthmatic subjects.

Koenig, J.Q.; Pierson, W.E.; Horike, M.

1983-08-01

382

First gaseous sulfuric acid measurements in automobile exhaust: Implications for volatile nanoparticle formation  

NASA Astrophysics Data System (ADS)

Gaseous sulfuric acid (GSA) is thought to represent an important if not the most important nucleating gas present in modern diesel automobile exhaust. It triggers the formation of new aerosol particles, which grow by condensation and coagulation. Here we report on the first measurements of GSA in automobile exhaust. The experiment was made using a modern passenger diesel car equipped with an exhaust after-treatment system composed of an oxidation catalyst and a diesel-particle filter. The diesel fuel used had an ultra-low sulfur mass fraction of only 5×10 -6. Measured GSA number concentrations reached up to 1×10 9 cm -3. Freshly nucleated particles with diameters larger than 3 nm were also measured. The concentrations reached up to 1×10 5 cm -3 and were positively correlated with GSA for GSA exceeding a threshold value in the range of 5×10 7-2×10 8 cm -3. This suggests that GSA was involved in the formation of new volatile particles.

Arnold, F.; Pirjola, L.; Aufmhoff, H.; Schuck, T.; Lähde, T.; Hämeri, K.

383

Improved Synthesis of 5-Substituted 1H-Tetrazoles via the [3+2] Cycloaddition of Nitriles and Sodium Azide Catalyzed by Silica Sulfuric Acid  

PubMed Central

A silica supported sulfuric acid catalyzed [3+2] cycloaddition of nitriles and sodium azide to form 5-substituted 1H-tetrazoles is described. The protocol can provide a series of 5-substituted 1H-tetrazoles using silica sulfuric acid from nitriles and sodium azide in DMF in 72%–95% yield. PMID:22606004

Du, Zhenting; Si, Changmei; Li, Youqiang; Wang, Yin; Lu, Jing

2012-01-01

384

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

NASA Technical Reports Server (NTRS)

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

Tompson, Robert V., Jr.

1991-01-01

385

Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera.  

PubMed

The time-resolved spectra of single-bubble sonoluminescence (SBSL) in sulfuric acid have been observed with a streak camera after a spectrograph. The spectral center evolves from infrared to ultraviolet gradually within a SBSL duration, which corresponds to an increase of temperature. The peak temperature within one sonoluminescence (SL) duration is 5-9 times higher than the average temperature based on the average spectrum in our experiment. Furthermore, the ratio of the peak temperature to average temperature increases with the increase of driving pressure. The SBSL flash dies out after a dramatic heating-up, and there is no cooling procedure observed at the time resolution of 110 SL duration, which is incompatible with the radius-related adiabatic heating model as the mechanism of SBSL. PMID:18851095

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

2008-09-01

386

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

SciTech Connect

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

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

2010-06-10

387

Accumulation of different sulfur fractions in Chinese forest soil under acid deposition.  

PubMed

Atmogenic sulfur (S) deposition loading by acid rain is one of the biggest environmental problems in China. It is important to know the accumulated S stored in soil, because eventually the size (and also the "desorption" rate) determines how rapidly the soil water pH responds to decrease in S deposition. The S fractions and the ratio of total carbon/total sulfur (C/S) of forest soil in 9 catchments were investigated by comparing soils at the rural and urban sites in China. The S fractions included water-soluble sulfate-S (SO(4)-S), adsorbed SO(4)-S, insoluble SO(4)-S and organic S. The ratio of C/S in soil at the rural site was significantly (p < 0.05) greater than that at the urban site. C/S of soil in the A horizon was significantly (p < 0.05) and negatively correlated with the wet S-deposition rate. The ratio of C/S presents a better indicator for atmogenic S loading. Organic S was the dominant form in soils at rural sites; contributing more than 69% of the total S in the uppermost 30 cm soil. Organic S and adsorbed SO(4)-S were the main forms of S in soil at urban sites. High contents of water-soluble SO(4)-S and adsorbed SO(4)-S were found in uppermost 30 cm soils at urban sites but not at rural sites. Decades of acid rain have caused accumulation of inorganic SO(4)-S in Chinese forest soil especially at the urban sites. The soil at urban sites had been firstly acidified, and the impacts on the forest ecosystem in these areas should be noticed. PMID:21779600

Wang, Zhanyi; Zhang, Xiaoshan; Zhang, Yi; Wang, Zhangwei; Mulder, Jan

2011-09-01

388

Enhanced histamine release from lung mast cells of guinea pigs exposed to sulfuric acid aerosols  

SciTech Connect

To clarify the relationship between air pollution and mast cell response, the effects of sulfuric acid aerosols on histamine release from lung mast cells of guinea pigs were investigated. Guinea pigs were exposed to 0.3, 1.0 and 3.2 mg/m{sup 3} sulfuric acid (H{sub 2}SO{sub 4}) aerosols or 4 ppm nitrogen dioxide (NO{sub 2}) for 2 and 4 weeks. After the exposure, lung mast cell suspensions were isolated by collagenase treatment and antigen- or A23187-induced histamine release was measured. Antigen-induced histamine release from mast cells was significantly enhanced by the exposure to 1.0 and 3.2 mg/m{sup 3} H{sub 2}SO{sub 4} for 2 weeks, but exposure to H{sub 2}SO{sub 4} for 4 weeks did not show the enhancement of antigen-induced histamine release. A23187-induced histamine release was significantly enhanced by the exposure to 1.0 mg/m{sup 3} H{sub 2}SO{sub 4} or 4 ppm NO{sub 2} for 2 weeks, but suppression of histamine release from lung mast cells stimulated with A23187 was observed by the exposure to 3.2 mg/m{sup 3} H{sub 2}So{sub 4} for 4 weeks. The exposure to 0.3 mg/m{sup 3} H{sub 2}So{sub 4} showed no changes in antigen- and A23187-induced histamine release. The combination of 1.0 mg/m{sup 3} H{sub 2}So{sub 4} with 4 ppm NO{sub 2} for 2 weeks resulted in no changes in antigen- and A23187-induced histamine release. These results suggested that functional properties of lung mast cells may be altered by a low concentration of H{sub 2}So{sub 4} aerosol exposure.

Fujimaki, Hidekazu (National Inst. for Environmental Studies, Ibaraki (Japan)); Katayama, Noboru; Wakamori, Kazuo (Univ. School of Medicine, Tokyo (Japan))

1992-06-01

389

NMR study of the role of isopropylsulfates in the two-step “conjunct oligomerization” of propylene and isopentane–propylene alkylation catalyzed by 95% sulfuric acid  

Microsoft Academic Search

“Conjunct oligomerization” of propylene or the isopentane–propylene alkylation catalyzed by an excess of 95% sulfuric acid\\u000a was performed in two consecutive steps. First di-isopropylsulfate was prepared by interaction of sulfuric acid with propylene.\\u000a The ester was then either decomposed at room temperature in the presence of the 5–10 molar excess of 95% acid or was used\\u000a in the acid-catalyzed alkylation

V. B. Kazansky; H. C. L. Abbenhuis; R. A. van Santen; M. L. V. Vorstenbosch

2000-01-01

390

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

SciTech Connect

Some experimental work is presented that is related to two hybrid thermochemical cycles for the production of hydrogen which involve bismuth trisulfate and/or bismuth oxysulfates. Omitting statement of the steps for decomposition of SO/sub 3/ and the electrochemical formation of H/sub 2/ and H/sub 2/SO/sub 4/ from SO/sub 2/ and H/sub 2/O, the high and low temperature reactions are: Cycle I - Bi/sub 2/(SO/sub 4/)/sub 3/ = Bi/sub 2/O/sub 2/ /sub 3/ (SO/sub 4/)/sub 0/ /sub 7/ + 2.3 SO/sub 3/; and Bi/sub 2/O/sub 2/ /sub 3/(SO/sub 4/)/sub 0/ /sub 7/ + 2.3 H/sub 2/SO/sub 4/ = Bi/sub 2/(SO/sub 4/)/sub 3/ + 2.3 H/sub 2/O. Cycle II - Bi/sub 2/O(SO/sub 4/)/sub 2/ = Bi/sub 2/O/sub 2/ /sub 3/(SO/sub 4/)/sub 0/ /sub 7/ + 1.3 SO/sub 3/; and Bi/sub 2/O/sub 2/ /sub 3/(SO/sub 4/)/sub 0/ /sub 7/ + 1.3 H/sub 2/SO/sub 4/ = Bi/sub 2/O(SO/sub 4/)/sub 2/ + 1.3 H/sub 2/O. Equilibrium sulfur trioxide pressures are given graphically for three solid-gas equilibria involving Bi/sub 2/(SO/sub 4/)/sub 3/, ..cap alpha..- and ..beta..-Bi/sub 2/O(SO/sub 4/)/sub 2/, and Bi/sub 2/O/sub 2/SO/sub 4/. An improved method of carrying out the low temperature step for Cycle I 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 SO/sub 2/ and O/sub 2/ are evolved at different temperatures, simplifying the usual SO/sub 3/-SO/sub 2/-O/sub 2/ separation problem.

Jones, W.M.

1982-01-01

391

AN EFFICIENT AND CHEMOSELECTIVE CBZ-PROTECTION OF AMINES USING SILICA-SULFURIC ACID AT ROOM TEMPERATURE  

EPA Science Inventory

A simple, facile, and chemoselective N-benzyloxycarbonylation of amines using silica-sulfuric acid that proceeds under solvent-free conditions at room temperature has been achieved. These reactions are applicable to a wide variety of primary (aliphatic, cyclic) secondary amines, ...

392

Efficiency of Sulfuric Acid, Mined Gypsum, and Two Gypsum By-Products in Soil Crusting Prevention and Sodic Soil Reclamation  

Microsoft Academic Search

face runoff and erosion (Sumner and Stewart, 1992). Al- though not properly quantified, soil crusting has been Sulfuric acid and gypsum-like by-products are potentially effective identified as a moderate to severe problem in different amendments in preventing soil crusting and reclaiming calcareous sodic soils. However, their relative efficiencies at chemically equiva- soils of the middle Ebro River Basin (Spain), whereas

E. Amezketa; R. Aragüés; R. Gazol

2005-01-01

393

Removal of sulfuric acid aerosol in a wet electrostatic precipitator with single terylene or polypropylene collection electrodes  

Microsoft Academic Search

Wet electrostatic precipitators (ESPs) are good options for effective control of sulfuric acid aerosol emission. However, various problems caused by materials and non-uniform distribution of water film limited the applicability of typical wet ESPs. Research on ESP technology has tried to find more suitable and anti-corrosive methods to solve these imperfections. This research was inspired by the requirement to replace

Jingcai Chang; Yong Dong; Zhiqiang Wang; Peng Wang; Peng Chen; Chunyuan Ma

2011-01-01

394

Effects of sulfuric acid treatment on the microstructure and electrochemical performance of a polyacrylonitrile (PAN)-based carbon anode  

Microsoft Academic Search

To examine whether acid treatment of a non-graphitizing hard carbon influences positively or negatively its electrochemical anodic performance, this study reports the effects of sulfuric acid treatment on the microstructural changes and electrochemical performance of PAN-based hard carbons prepared at various temperatures. It was found that PAN-based hard carbons heat treated at 900°C (TAN9) exhibit an increased reversible capacity by

Y. J. Kim; H. J. Lee; S. W. Lee; B. W. Cho; C. R. Park

2005-01-01

395

Study of selectivity of iodide membrane electrode in autooscillatory potassium iodate-hydrogen peroxide-cysteine-sulfuric acid systems  

SciTech Connect

In the potassium iodate-hydrogen peroxide-cysteine-sulfuric acid system, the authors studied the selectivity of the membrane electrode for a given type of ions at variable concentrations of other components, with particular attention to the influence of the initial concentrations of the various acids on the shift of the iodide selective electrode potential, taking into account the redox reactions between these components in an oscillatory system.

Protopopov, E.V.; Zueva, T.S.

1985-05-01

396

Highly Selective Liquid–Liquid Extraction from Sulfuric Acid Medium and Spectrophotometric Determination of Palladium(II) with ?-Benzilmonoxime  

Microsoft Academic Search

A selective method for the extraction and spectrophotometric determination of palladium with ?-benzilmonoxime (BZ) is described. BZ–Pd(II) complex was extracted from acidic aqueous solution (1.5 M sulfuric acid) into a chloroform layer. Absorbance was measured at 434 nm and molar absorptivity was found to be about 1.0 × 104 cm?1 mol?1 liter?1. Beer's law is obeyed over the range 0.300

Ali A. Ensafi; H. Eskandari

1999-01-01

397

Influence of dilute acid and alkali pretreatment on reducing sugar production from corncobs by crude enzymatic method: a comparative study.  

PubMed

In the present study, two commonly used catalysts in chemical pretreatment, sulfuric acid and sodium hydroxide, were tested to evaluate the effect of solid-to-liquid ratio on pretreatment and enzymatic hydrolysis. Solid to liquid ratio (S/L) was influential on sugars released with an increase in the S/L ratio between 0.03 and 0.2. Enzymatic digestibility of 0.25 M H2SO4 pretreated corncobs were released more sugars (415.12 mg/mL); whereas, corncobs pretreated with NaOH released 350.12 mg/mL of reducing sugars at S/L 0.05. Further, in comparison with NaOH pretreated corncobs, acid treated material substantially increased the accessibility and digestibility of cellulose during crude enzymatic hydrolysis (28.96 FPU) and released 398.95 mg/mL reducing sugars. PMID:24755319

Baadhe, Rama Raju; Potumarthi, Ravichandra; Mekala, Naveen Kumar

2014-06-01

398

Total 4EBP1 Is Elevated in Liver of Rats in Response to Low Sulfur Amino Acid Intake  

PubMed Central

Translation initiation is known to be regulated by the binding of eukaryotic initiation factor 4E (eIF4E) by binding proteins (4EBPs), and there is evidence that amino acid deprivation and other cellular stresses upregulate 4EBP1 expression. To pursue the question of whether diets limited in an essential amino acid lead to induction of 4EBP1 expression in vivo, diets that varied in methionine and cystine content were fed to rats for 7 days, and 4EBP1 mRNA and protein levels and 4EBP1 phosphorylation state were determined. Total 4EBP1 mRNA and protein abundance increased in liver of rats with severely deficient intakes of sulfur amino acids (0.23% or 0.11% methionine without cystine) but not in animals with a less restricted intake of sulfur amino acids (0.11% methionine plus 0.35% cystine) but a similarly restricted intake of total diet (53 to 62% of control). The amount of 4EBP1 binding activity (? + ? forms) was elevated in liver of rats fed sulfur amino acid-deficient diets, whereas the hyperphosphorylation of 4EBP1 was not affected by dietary treatment. Results suggest that changes in total 4EBP1 expression should be considered when examining mechanisms that attenuate protein synthesis during amino acid deficiency states. PMID:24089634

Sikalidis, Angelos K.; Mazor, Kevin M.; Kang, Minji; Liu, Hongyun; Stipanuk, Martha H.

2013-01-01

399

Biotechnological production of xylitol: enhancement of monosaccharide production by post-hydrolysis of dilute acid sugarcane hydrolysate.  

PubMed

Dilute-acid hydrolysis pretreatment of sugarcane bagasse resulted in release of 48% (18.4 g/L) of the xylan in the hemicellulose fraction into the hydrolysate as monomeric xylose. In order to enhance the recuperation of this monomer, a post-hydrolysis stage consisted of thermal treatment was carried out. This treatment resulted in an increase in xylose release of 62% (23.5 g/L) of the hemicellulose fraction. Original and post-hydrolysates were concentrated to the same levels of monomeric xylose in the fermentor feed. During the fermentation process, cellular growth was observed to be higher in the post-hydrolysate (3.5 g/L, Y(x/s) = 0.075 g cells/g xylose) than in the original hydrolysate (2.9 g/L, Y(x/s) = 0.068 g cells/g xylose). The post-treated hydrolysate required less concentration of sugars resulting in a lower concentration of fermentation inhibitors, which were formed primarily in the dilute acid hydrolysis step. Post-hydrolysis step led to a high xylose-xylitol conversion efficiency of 76% (0.7 g xylitol/g xylose) and volumetric productivity of 0.68 g xylitol/L h when compared to 71% (0.65 g xylitol/g xylose and productivity of 0.61 g xylitol/L h) for the original hemicellulosic hydrolysate. PMID:19214792

Sarrouh, Boutros Fouad; de Freitas Branco, Ricardo; da Silva, Silvio Silvério

2009-05-01

400

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

SciTech Connect

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

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

1999-11-01

401

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

PubMed

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

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

2014-04-01

402

Effects of SPORL and dilute acid pretreatment on substrate morphology, cell physical and chemical wall structures, and subsequent enzymatic hydrolysis of lodgepole pine.  

PubMed

The effects of pretreatment by dilute acid and sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) on substrate morphology, cell wall physical and chemical structures, along with the subsequent enzymatic hydrolysis of lodgepole pine substrate were investigated. FE-SEM and TEM images of substrate structural morphological changes showed that SPORL pretreatment resulted in fiber separation, where SPORL high pH (4.2) pretreatment exhibited better fiber separation than SPORL low pH (1.9) pretreatment. Dilute acid pretreatment produced very poor fiber separation, consisting mostly of fiber bundles. The removal of almost all hemicelluloses in the dilute acid pretreated substrate did not overcome recalcitrance to achieve a high cellulose conversion when lignin removal was limited. SPORL high pH pretreatment removed more lignin but less hemicellulose, while SPORL low pH pretreatment removed about the same amount of lignin and hemicelluloses in lodgepole pine substrates when compared with dilute acid pretreatment. Substrates pretreated with either SPORL process had a much higher cellulose conversion than those produced with dilute acid pretreatment. Lignin removal in addition to removal of hemicellulose in SPORL pretreatment plays an important role in improving the cellulose hydrolysis of the substrate. PMID:22968589

Li, Xinping; Luo, Xiaolin; Li, Kecheng; Zhu, J Y; Fougere, J Dennis; Clarke, Kimberley

2012-11-01

403

Response of DOC in Acid-Sensitive Maine Lakes to Decreasing Sulfur Deposition (1993 - 2009)  

NASA Astrophysics Data System (ADS)

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, there has been a concurrent increase in dissolved organic carbon (DOC) concentrations in many lakes and streams which has been difficult to interpret. To assess the biogeochemical processes driving increasing DOC concentrations we analyzed archived samples from 9 acid-sensitive lakes in Maine collected between 1993 and 2009 using UV-Vis and fluorescence spectroscopy. The fluorescence index (FI) was calculated for all samples. The FI represents the ratio of the emission intensity at 450 nm to 550 nm at an excitation wavelength of 370 nm and provides information regarding the source of dissolved organic matter (DOM). This index has a value of approximately 1.9 for microbially derived fluvic acids and a value of approximately 1.4 for terrestrially (higher-plant) derived fluvic acids. All four lakes with increasing DOC trends had concomitant decreases in the FI index. Two of five lakes with no significant DOC trend also demonstrated no trend in FI values over time, while three lakes revealed a decrease in FI values. To confirm that the FI measured in whole water was primarily reflective of fulvic acids (FA), XAD-resin was used to isolate FA from a subset of samples. Analysis of the FA indicates that the FI values for the humic substances are slightly higher, yet well correlated with whole water samples. This suggests that despite prolonged storage in plastic, the FI trends are meaningful. The FI trends suggest a terrestrial source for the increasing DOC and may be driven by increased DOM production from soils experiencing decreased acid loading. Decreases in sulfate deposition can increase soil pH and soil organic matter solubility, as well as decrease the ionic strength of the soil solution, and increase DOC flux. This abstract does not necessarily reflect EPA policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Oelsner, G. P.; Sanclements, M.; McKnight, D. M.; Stoddard, J. L.

2010-12-01

404

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403  

PubMed Central

Cysteine and methionine availability influences many processes in the cell. In bacteria, transcription of the specific genes involved in the synthesis of these two amino acids is usually regulated by different mechanisms or regulators. Pathways for the synthesis of cysteine and methionine and their interconversion were experimentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food. A new gene, yhcE, was shown to be involved in methionine recycling to cysteine. Surprisingly, 18 genes, representing almost all genes of these pathways, are under the control of a LysR-type activator, FhuR, also named CmbR. DNA microarray experiments showed that FhuR targets are restricted to this set of 18 genes clustered in seven transcriptional units, while cysteine starvation modifies the transcription level of several other genes potentially involved in oxidoreduction processes. Purified FhuR binds a 13-bp box centered 46 to 53 bp upstream of the transcriptional starts from the seven regulated promoters, while a second box with the same consensus is present upstream of the first binding box, separated by 8 to 10 bp. O-Acetyl serine increases FhuR binding affinity to its binding boxes. The overall view of sulfur amino acid metabolism and its regulation in L. lactis indicates that CysE could be a master enzyme controlling the activity of FhuR by providing its effector, while other controls at the enzymatic level appear to be necessary to compensate the absence of differential regulation of the genes involved in the interconversion of methionine and cysteine and other biosynthesis genes. PMID:15901700

Sperandio, Brice; Polard, Patrice; Ehrlich, Dusko S.; Renault, Pierre; Guédon, Eric

2005-01-01

405

Dilute Acetic Acid Exposure Enhances Electrolyte Leakage by Hydrilla verticillata and Potamogeton pectinatus Tubers  

Microsoft Academic Search

Subterranean vegetative propagules are important life cycle stages for some species of rooted aquatic plants. Sedi- ments contain numerous compounds resulting from anaero- bic degradation of organic matter, including acetic acid. Tubers of hydrilla (Hydrilla verticillata (L.f.) Royle) and sago pondweed ( Potamogeton pectinatus L. ) were exposed to a range of acetic acid concentrations (0, 17.4, 87, 174, 348,

DAVID F. SPENCER; G. G. KSANDER

406

Heterogeneous Reactions of ClONO2, HCl, and HOCl on Liquid Sulfuric Acid Surfaces  

NASA Technical Reports Server (NTRS)

The heterogeneous reactions of ClONO2 + H2O yields HNO3 + HOCl (1), ClONO2 + HCl yields C12 + HNO3 (2), and HOCl + HCl yields Cl2 + H2O (3) on liquid sulfuric acid surfaces have been studied using a fast flow reactor coupled to a quadrupole mass spectrometer. The main objectives of the study are to investigate: (a) the temperature dependence of these reactions at a fixed H2O partial pressure typical of the lower stratosphere (that is, by changing temperature at a constant water partial pressure, the H2SO4 content of the surfaces is also changed), (b) the relative importance or competition between reactions 1 and 2, and (c) the effect of HNO3 on the reaction probabilities due to the formation of a H2SO4/HNO3/H2O ternary system. The measurements show that all the reactions depend markedly on temperature at a fixed H2O partial pressure: they proceed efficiently at temperatures near 200 K and much slower at temperatures near 220 K. The reaction probability (gamma(sub 1)) for ClONO2 hydrolysis approaches 0.01 at temperatures below 200 K, whereas the values for gamma(sub 2) and gamma(sub 3) are on the order of a few tenths at 200 K. Although detailed mechanisms for these reactions are still unknown, the present data indicate that the competition between ClONO2 hydrolysis and ClONO2 reaction with HCl may depend on temperature (or H2SO4 Wt %): in the presence of gaseous HCl at stratospheric concentrations, reaction 2 is dominant at lower temperatures (less than 200 K), but reaction 1 becomes important at temperatures above 210 K. Furthermore, reaction probability measurements performed on the H2SO4/HNO3/ H2O ternary solutions do not exhibit noticeable deviation from those performed on the H2SO4/H2O binary system, suggesting little effect of HNO3 in sulfate aerosols on the ClONO2 and HOCl reactions with HCl. The results reveal that significant reductions in the chlorine-containing reservoir species (such as ClONO2 and HCl) can take place on stratospheric sulfate aerosols at high latitudes in winter and early spring, even at temperatures too warm for Polar Stratospheric Clouds (PSCs) to form or in regions where nucleation of PSCs is sparse. This is particularly true under elevated sulfuric acid loading, such as that after the eruption of Mt. Pinatubo. Comparisons between our results and those presently available have also been made.

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

1994-01-01

407

Comparison of isotope dilution and excretion methods for determining the half-life of ascorbic acid in the guinea pig  

SciTech Connect

The half-life of ascorbic acid (AA) in guinea pigs was investigated by the isotope dilution and excretion methods. The dilution method measures (1-14C)AA disappearance from the plasma, whereas the excretion method measures the elimination of (1-14C)AA and the metabolites from the body. Two groups of animals underwent both isotope studies in reverse order. Animals were conditioned to the experimental procedures and fed 2.5 mg AA/100 g body weight orally to maintain a daily intake of the vitamin independent of food consumption. The two isotope procedures imposed similar stress on the animals, as determined by plasma cortisol levels and body weight changes. The AA half-life calculations of the rapidly exchangeable pool by the isotope dilution method yielded values of 1.23 and 0.34 hours for the two groups, respectively. The half-life of the slowly exchangeable pool for the two groups was 60.2 and 65.8 hours, respectively. The half-life of AA in the rapidly exchangeable pool, as measured by the excretion studies, was 4.57-8.75 hours. For the slowly exchangeable pool, it was 146-149 hours. The longer half-life of both pools obtained with the excretion method indicates that the isotope is disappearing from the plasma more rapidly than it is being excreted. This suggests that a portion of the (1-14C)AA leaving the plasma is removed to a body pool that is not sampled by the isotope excretion method.

Kipp, D.E.; Rivers, J.M.

1984-08-01

408

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

PubMed

Dilute H(3)PO(4) (0.0-2.0%, v/v) was used to pretreat corn stover (10%, w/w) for conversion to ethanol. Pretreatment conditions were optimized for temperature, acid loading, and time using central composite design. Optimal pretreatment conditions were chosen to promote sugar yields following enzymatic digestion while minimizing formation of furans, which are potent inhibitors of fermentation. The maximum glucose yield (85%) was obtained after enzymatic hydrolysis of corn stover pretreated with 0.5% (v/v) acid at 180°C for 15min while highest yield for xylose (91.4%) was observed from corn stover pretreated with 1% (v/v) acid at 160°C for 10min. About 26.4±0.1g ethanol was produced per L by recombinant Escherichia coli strain FBR5 from 55.1±1.0g sugars generated from enzymatically hydrolyzed corn stover (10%, w/w) pretreated under a balanced optimized condition (161.81°C, 0.78% acid, 9.78min) where only 0.4±0.0g furfural and 0.1±0.0 hydroxylmethyl furfural were produced. PMID:23334017

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

2013-02-01

409

First online measurements of sulfuric acid gas in modern heavy-duty diesel engine exhaust: implications for nanoparticle formation.  

PubMed

To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes. PMID:23035617

Arnold, F; Pirjola, L; Rönkkö, T; Reichl, U; Schlager, H; Lähde, T; Heikkilä, J; Keskinen, J

2012-10-16

410

Nanopore formation on the surface oxide of commercially pure titanium grade 4 using a pulsed anodization method in sulfuric acid.  

PubMed

Titanium and its alloys form a thin amorphous protective surface oxide when exposed to an oxygen environment. The properties of this oxide layer are thought to be responsible for titanium and its alloys biocompatibility, chemical inertness, and corrosion resistance. Surface oxide crystallinity and pore size are regarded to be two of the more important properties in establishing successful osseointegration. Anodization is an electrochemical method of surface modification used for colorization marking and improved bioactivity on orthopedic and dental titanium implants. Research on titanium anodization using sulphuric acid has been reported in the literature as being primarily conducted in molarity levels 3 M and less using either galvanostatic or potentiostatic methods. A wide range of pore diameters ranging from a few nanometers up to 10 ?m have been shown to form in sulfuric acid electrolytes using the potentiostatic and galvanostatic methods. Nano sized pores have been shown to be beneficial for bone cell attachment and proliferation. The purpose of the present research was to investigate oxide crystallinity and pore formation during titanium anodization using a pulsed DC waveform in a series of sulfuric acid electrolytes ranging from 0.5 to 12 M. Anodizing titanium in increasing sulfuric acid molarities showed a trend of increasing transformations of the amorphous natural forming oxide to the crystalline phases of anatase and rutile. The pulsed DC waveform was shown to produce pores with a size range from ?0.01 to 1 ?m(2). The pore size distributions produced may be beneficial for bone cell attachment and proliferation. PMID:23807314

Williamson, R S; Disegi, J; Griggs, J A; Roach, M D

2013-10-01

411

Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.  

PubMed

We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system. PMID:23290939

Yagyu, Daisuke; Ohishi, Tetsuo; Igarashi, Takeshi; Okumura, Yoshikuni; Nakajo, Tetsuo; Mori, Yuichiro; Kobayashi, Sh?

2013-03-01

412

A Procedure for the Fractionation of Aqueous Aluminum in Dilute Acidic Waters  

Microsoft Academic Search

A procedure was developed for the fractionation of aqueous aluminum. This procedure results in the determination of acid-soluble aluminum, non-labile monomeric aluminum and labile monomeric aluminum. Acid-soluble aluminum is thought to include colloidal aluminum and extremely non-labile organic complexes. Non-labile monomeric aluminum is thought to include monomeric alumino-organic complexes. Labile monomeric is comprised of aquo aluminum as well as inorganic

Charles T. Driscoll

1984-01-01

413

Dissolution of mechanically activated Panzhihua ilmenites in dilute solutions of sulphuric acid  

Microsoft Academic Search

Dissolution of mechanically activated Panzhihua ilmenite was conducted in 5–20% sulphuric acid solutions. With high milling intensity the milling atmosphere significantly affected the dissolution with milling under vacuum almost double the dissolution of ilmenite milled in air. This was due to formation of a lot of acid-resistant pseudorutile and lowering level of the lattice strains, especially in the c-axis direction

Chun Li; Bin Liang; Ling-hong Guo

2007-01-01

414

Prehydrolysis of Eucalyptus wood with dilute sulphuric acid: operation in autoclave  

Microsoft Academic Search

The production of xylose fromEucalyptus globulus wood samples in media containing sulphuric acid was studied. The prehydrolysis reactions were carried out in autoclave. All\\u000a the experiments were performed with liquid\\/wood ratio of 10 g\\/g. The effects of sulphuric acid concentration (within the range\\u000a 2–6%), reaction time (0–6 h) and temperature (115 or 130°C) on the type and distribution of reaction

J. C. Parajó; D. Vázquez; J. L. Alonso; V. Santos; H. Domínguez

1994-01-01

415

Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry  

NASA Astrophysics Data System (ADS)

The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3- ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (americium-241) ion source which has been used previously. The results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of 1 min it is ~6 × 104 molecule cm-3 of H2SO4. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.

Kürten, A.; Rondo, L.; Ehrhart, S.; Curtius, J.

2011-03-01

416

Performance of a corona ion source for measurement of sulfuric acid by chemical ionization mass spectrometry  

NASA Astrophysics Data System (ADS)

The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3- ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (Americium 241) ion source which has been used previously. Our results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of one minute it is ~6 × 104 molecules of H2SO4 per cm3. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.

Kürten, A.; Rondo, L.; Ehrhart, S.; Curtius, J.

2010-11-01

417

Neutral molecular cluster formation of sulfuric acid-dimethylamine observed in real time under atmospheric conditions  

PubMed Central

For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even though the neutral particles are stable against evaporation from the SA dimer onward, the formation rates of particles at 1.7-nm size, which contain about 10 SA molecules, are up to 4 orders of magnitude smaller compared with those of the dimer due to coagulation and wall loss of particles before they reach 1.7 nm in diameter. This demonstrates that neither the atmospheric particle formation rate nor its dependence on SA can simply be interpreted in terms of cluster evaporation or the molecular composition of a critical nucleus. PMID:25288761

Kurten, Andreas; Jokinen, Tuija; Simon, Mario; Sipila, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, Joao; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petaja, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H.; Steiner, Gerhard; Tome, Antonio; Trostl, Jasmin; Winkler, Paul M.; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S.; Kulmala, Markku; Worsnop, Douglas R.; Curtius, Joachim

2014-01-01

418

Neutral molecular cluster formation of sulfuric acid-dimethylamine observed in real time under atmospheric conditions.  

PubMed

For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even though the neutral particles are stable against evaporation from the SA dimer onward, the formation rates of particles at 1.7-nm size, which contain about 10 SA molecules, are up to 4 orders of magnitude smaller compared with those of the dimer due to coagulation and wall loss of particles before they reach 1.7 nm in diameter. This demonstrates that neither the atmospheric particle formation rate nor its dependence on SA can simply be interpreted in terms of cluster evaporation or the molecular composition of a critical nucleus. PMID:25288761

Kürten, Andreas; Jokinen, Tuija; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Riccobono, Francesco; Rissanen, Matti P; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H; Steiner, Gerhard; Tomé, António; Tröstl, Jasmin; Winkler, Paul M; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S; Kulmala, Markku; Worsnop, Douglas R; Curtius, Joachim

2014-10-21

419

Phase transformations in sulfuric acid aerosols: Implications for stratospheric ozone depletion  

SciTech Connect

Activation reactions of benign chlorine species (HCl, CIONO{sub 2}) on aerosols in the winter polar stratosphere set the stage for the spring-time catalytic destruction of ozone leading to the Antarctic ozone hole. Field observations have demonstrated the existence of both solid and liquid particles consisting of H{sub 2}SO{sub 4}, HNO{sub 3}, and H{sub 2}O. The exact freezing conditions and final composition of the solid aerosols remain the subject of investigations. We present laboratory observations of isolated individual sulfuric acid/water particles under stratospheric temperatures and water vapor pressures. Our experiments demonstrate that this binary system would not freeze unless temperatures were below the water-ice frost point. Upon freezing, we observe H{sub 2}SO{sub 4}{minus}8H{sub 2}O, not the generally invoked H{sub 2}SO{sub 4}{minus}4H{sub 2}O. We suggest that the water-rich octahydrate phase is likely to be one of the high relative humidity forms which is efficient in chlorine activation.{copyright} 1997 American Geophysical Union

Imre, D.G. [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States)] [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States); Xu, J. [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States)] [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States); [Institute of Terrestrial and Planetary Atmospheres, State University of , New York 11794 (United States); Tridico, A.C. [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States)] [Environmental Chemistry Division, Department of Applied Science, Brookhaven National Laboratory, Upton, New York (United States)

1997-01-01

420

An inlet/sampling duct for airborne OH and sulfuric acid measurements  

NASA Astrophysics Data System (ADS)

An inlet assembly has been designed, tested, and used for the airborne measurements of OH and sulfuric acid. The inlet sampling duct, which incorporates a shroud connected to two nested, restricted flow ducts, slows air velocity by approximately a factor of 16 while maintaining a uniform and well-defined flow. Qualitative wind tunnel tests showed that an inlet shroud that incorporates a 3:1 inner surface and 4.5:1 outer elliptical front surface can straighten the airflow at angles of attack of up to 18°-20° with no visible signs of turbulence. Tests using a Pitot tube to scan the flow velocity profile of the restricted flow ducts showed that the shroud, coupled to inlet ducts, could slow the flow and provide a relatively flat average velocity profile across the central portion of the ducts at angles of attack up to 17°. Tests performed using a chemical tracer showed that at angles of attack where the Pitot tube measurements began to indicate slight flow instabilities (17°-24°), there was no mixing from the walls into the center of the inlet. The inlet assembly also possesses the ability to produce a fairly uniform concentration of OH in the relatively constant velocity portion of the inner duct for instrument calibration. Actual measurements of rapidly changing OH and H2SO4 provide both additional evidence of proper inlet operation and new insight into H2SO4 production and loss in and around clouds.

Eisele, F. L.; Mauldin, R. L.; Tanner, D. J.; Fox, J. R.; Mouch, T.; Scully, T.

1997-12-01

421

Electrochemical behavior of lead alloys in sulfuric and phosphoric acid solutions  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of lead, lead-antimony, and lead-calcium-aluminium-tin alloys has been studied in solutions containing various concentrations of sulfuric and phosphoric acids. The dependence of these electrode processes on some experimental conditions (mainly sweep rate and potential range) has been studied. The measurements were performed using a cyclic voltammetry technique. The study and the analysis of the morphology of alloys have been performed using a scanning electron microscope (SEM). Cyclic voltammograms of the lead-antimony alloy electrodes, similarly to pure lead electrode, also show the "anodic excursion" peak under some experimental conditions. Well defined current waves, corresponding to the oxidation and reduction processes of Sb, are observed, if the alloy surface is freshly abraded. The oxidation of antimony starts at potentials at which the formation of PbO takes place. The peak current of Sb oxidation reaction decreases during successive cycles, suggesting that Sb dissolves from the alloy surface during the first CV sweeps. Another explanation for this effect might be the formation of a PbSO 4 selective membrane.

Paleska, I.; Pruszkowska-Drachal, R.; Kotowski, J.; Dziudzi, A.; Milewski, J. D.; Kopczyk, M.; Czerwi?ski, A.

422

Stratospheric sulfuric acid fraction and mass estimate for the 1982 volcanic eruption of El Chichon  

NASA Technical Reports Server (NTRS)

The stratospheric sulfuric acid fraction and mass for the 1982 volcanic eruptions of El Chichon are investigated using data from balloon soundings at Laramie (41 deg N) and in southern Texas (27-29 deg N). The total stratospheric mass of these eruptions is estimated to be approximately 8 Tg about 6.5 months after the eruption with possibly as much as 20 Tg in the stratosphere about 45 days after the eruption. Observations of the aerosol in Texas revealed two primary layers, both highly volatile at 150 C. Aerosol in the upper layer at about 25 km was composed of an approximately 80 percent H2SO4 solution while the lower layer at approximately 18 km was composed of a 60-65 percent H2SO4 solution aerosol. It is calculated that an H2SO4 vapor concentration of at least 3 x 10 to the 7th molecules/cu cm is needed to sustain the large droplets in the upper layer. An early bi-modal nature in the size distribution indicates droplet nucleation from the gas phase during the first 3 months, while the similarity of the large particle profiles 2 months apart shows continued particle growth 6.5 months after the explosion.

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

1983-01-01

423

[Determination of polysaccharides content of Gentiana farreri from different producing areas based on anthrone-sulfuric acid method].  

PubMed

Study a method for the detemination of the content of polysaccharides in Gentiana farreri, and analysis of the content of polysaccharides from different producing areas. The results showed that using the anthrone-sulfuric acid method, simple operation, accurate result. Sample was measured at 620 nm absorbance after anthrone-sulfuric acid color, at this wavelength, solution absorption and glucose showed a good linear relationship; The linearity was in the range of 0.01-0.07 g x L(-1) (r = 0.996 7). The recovery rate was 99.41%, with RSD of 2.0%. Considering the experimental conditions, to determine the solid-liquid ratio 1:60, extracting time 50 min, concentration of ethanol 80%. The mass fraction of polysaccharides was the highest to reached 0.743% in G. farreri from Gansu Xiahe. This experiment has laid a good foundation for further study on G. farreri. PMID:25272513

Lin, Li; Wang, Yan; Wang, Fu-Xing; He, Jia-Yan; Zhang, Hang-Lin

2014-07-01

424

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

Microsoft Academic Search

The trailing hemisphere of Jupiter's moon Europa is bombarded by charged particles trapped within Jupiter's magnetosphere. Sulfur ion implantation and impacting energetic electrons strongly affect the surface chemistry of Europa. Understanding these processes is important for disentangling the extrinsic and intrinsic components of Europa's surface chemistry. In the sulfur cycle model of Carlson et al. (Science 286, 97, 1999), hydrated

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

2010-01-01

425

Seasonal Variation of the Effect of Extremely Diluted Agitated Gibberellic Acid (10e-30) on Wheat Stalk Growth: A Multiresearcher Study  

PubMed Central

The influence of a homeopathic high dilution of gibberellic acid on wheat growth was studied at different seasons of the year. Seedlings were allowed to develop under standardized conditions for 7 days; plants were harvested and stalk lengths were measured. The data obtained confirm previous findings, that ultrahigh diluted potentized gibberellic acid affects stalk growth. Furthermore, the outcome of the study suggests that experiments utilizing the bioassay presented should best be performed in autumn season. In winter and spring, respectively, no reliable effects were found. PMID:22125426

Endler, Peter Christian; Matzer, Wolfgang; Reich, Christian; Reischl, Thomas; Hartmann, Anna Maria; Thieves, Karin; Pfleger, Andrea; Hofacker, Jurgen; Lothaller, Harald; Scherer-Pongratz, Waltraud

2011-01-01

426

Binding characteristics of Trichoderma reesei cellulases on untreated, ammonia fiber expansion (AFEX), and dilute-acid pretreated lignocellulosic biomass.  

PubMed

Studying the binding properties of cellulases to lignocellulosic substrates is critical to achieving a fundamental understanding of plant cell wall saccharification. Lignin auto-fluorescence and degradation products formed during pretreatment impede accurate quantification of individual glycosyl hydrolases (GH) binding to pretreated cell walls. A high-throughput fast protein liquid chromatography (HT-FPLC)-based method has been developed to quantify cellobiohydrolase I (CBH I or Cel7A), cellobiohydrolase II (CBH II or Cel6A), and endoglucanase I (EG I or Cel7B) present in hydrolyzates of untreated, ammonia fiber expansion (AFEX), and dilute-acid pretreated corn stover (CS). This method can accurately quantify individual enzymes present in complex binary and ternary protein mixtures without interference from plant cell wall-derived components. The binding isotherms for CBH I, CBH II, and EG I were obtained after incubation for 2 h at 4 °C. Both AFEX and dilute acid pretreatment resulted in increased cellulase binding compared with untreated CS. Cooperative binding of CBH I and/or CBH II in the presence of EG I was observed only for AFEX treated CS. Competitive binding between enzymes was found for certain other enzyme-substrate combinations over the protein loading range tested (i.e., 25-450 mg/g glucan). Langmuir single-site adsorption model was fitted to the binding isotherm data to estimate total available binding sites E(bm) (mg/g glucan) and association constant K(a) (L/mg). Our results clearly demonstrate that the characteristics of cellulase binding depend not only on the enzyme GH family but also on the type of pretreatment method employed. PMID:21437882

Gao, Dahai; Chundawat, Shishir P S; Uppugundla, Nirmal; Balan, Venkatesh; Dale, Bruce E

2011-08-01