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1

Sulfuric Acid and Water: Paradoxes of Dilution  

ERIC Educational Resources Information Center

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

Leenson, I. A.

2004-01-01

2

Dilute sulfuric acid pretreatment of sunflower stalks for sugar production.  

PubMed

In this work the pretreatment of sunflower stalks by dilute sulfuric acid is studied. Pretreatment temperature and the concentration of acid solution were selected as operation variables and modified according to a central rotatable composite experimental design. Based on previous studies pretreatment time was kept constant (5 min) while the variation range for temperature and acid concentration was centered at 175C and 1.25% (w/v) respectively. Following pretreatment the insoluble solids were separated by filtration and further submitted to enzymatic hydrolysis, while liquid fractions were analyzed for sugars and inhibitors. Response surface methodology was applied to analyze results based on the combined severity of pretreatment experiments. Optimized results show that up to 33 g of glucose and xylose per 100g raw material (65% of the glucose and xylose present in the raw material) may be available for fermentation after pretreatment at 167C and 1.3% sulfuric acid concentration. PMID:23708847

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

2013-05-06

3

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

Microsoft Academic Search

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

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

2003-01-01

4

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

PubMed

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

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

2007-09-29

5

Enthalpies of Dilution of Aqueous Electrolytes: Sulfuric Acid, Hydrochloric Acid, and Lithium Chloride.  

National Technical Information Service (NTIS)

Calorimetric measurements at 25 degrees C of the enthalpies of dilution of aqueous H2SO4 (0.00090 to 6.4 mol/kg), LiCl(0.026 to 6.7 mol/kg), and HCl(0.018 to 1.6 mol/kg) have been performed using two different isothermal calorimeters. The results of this ...

T. C. Wu T. F. Young

1979-01-01

6

Enthalpies of dilution of aqueous electrolytes: sulfuric acid, hydrochloric acid, and lithium chloride  

Microsoft Academic Search

Calorimetric measurements at 25 C of the enthalpies of dilution of aqueous HSO (0.00090 to 6.4 mol kg⁻¹), LiCl (0.026 to 6.7 mol kg⁻¹) have been performed using 2 different isothermal calorimeters. The results of this work and that of 3 earlier calorimetric investigations and one Raman spectral investigation have been used to calculate values of the relative apparent molal

Y. C. Wu; T. F. Young

2009-01-01

7

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

Microsoft Academic Search

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

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

2005-01-01

8

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

9

Ion flotation as a method of concentrating dilute solutions of uranium in sulfuric acid  

SciTech Connect

The results of experiments carried out in order to determine the possibility of extracting uranium by flotation from sulfuric acid solutions with the alkylpyridinium chlorides containing the following radicals is presented: decyl (DPC), dodecyl (doDPC), tridecyl (triDPC), tetradecyl (tetraDPC), pentadecyl (pentaDPC) and hexadecyl (hexaDPC); nicotinamide hydrobromides containing C/sub 10/-C/sub 18/ N-alkyl groups; hexadecylbenzyldimethylammonium bromide; bis(quaternary ammonium) salts of N,N' derivatives of hexamethylene- and ethylenediamine of the general formula )1,2-(N,N'-bis(dimethyl)-N,N'-bis(decylacetato))ethylenediammonium) dichloride (n = 2, R = C/sub 10/H/sub 21/) or ''ethonium (I)''; )1,2-(N,N'-bis(dimethyl)-N,N'-bis(decylacetato))hexamethylene-diammonium) dichloride (n = 6, R = C/sub 10/H/sub 21/) or ''ethonium (II)''; )1,2-(N,N'-bis(dimethyl)-N,N'-bis(dodecylacetato))hexamethylenediammonium) dichloride (n = 6, R = C/sub 12/H/sub 25/) or ''ethonium (III).'' Uranyl sulfate solutions of 0.005% concentration were used for the investigation. The solution pH was varied in the range 0.5-4.0. The sulfate-ion concentration was 0.1 g-ion/liter. The collectors (the surfactants listed above) were introduced into the uranium-containing test solutions in the form of 0.4% aqueous solutions, in the stoichiometric amounts required for binding UO/sub 2/(SO/sub 4/)/sub 3//sup 4 -/ anions. Flotation treatment of the solutions was continued for 20 min in the apparatus described in previous reports. The uranium and collector contents in the solutions were determined by standard methods. The zeta potentials of the sublate particles were determined electrophoretically.

Skrylev, L.D.; Menchuk, V.V.

1982-02-20

10

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

2011-04-03

11

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

PubMed Central

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

2012-01-01

12

Tribocorrosion behavior of Ti 3SiC 2 in the dilute and concentrated sulfuric acid solutions  

Microsoft Academic Search

In light of the salient physical and mechanical performance combined with good corrosive resistance, Ti3SiC2 is expected to be used as materials for mechanical component in corrosive environment. It is in necessity to investigate the tribocorrsion behavior of Ti3SiC2 in corrosive environment. In the electrochemical test, Ti3SiC2 experienced passivation when potential was positive than the corrosion potential in sulfuric acid

Shufang Ren; Junhu Meng; Jingbo Wang; Jinjun Lu; Shengrong Yang

2010-01-01

13

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

SciTech Connect

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

Frignani, A.; Trabanelli, G.

1999-07-01

14

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

SciTech Connect

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

Nguyen, D.T.

1994-10-01

15

Dilute Acid and Autohydrolysis Pretreatment  

NASA Astrophysics Data System (ADS)

Exposure of cellulosic biomass to temperatures of about 120-210C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such steam gun devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems.

Yang, Bin; Wyman, Charles E.

16

Principal reactions of airborne mercury, ozone and some other microcomponent in pure water or very dilute sulfuric acid  

Microsoft Academic Search

Numerous bubblings of pure H2O or very dilute H2SO4-solutions with ambient air have been undertaken. All of them have shown the formation of HgIIa and HgIIb in the liquid phase (nomenclature according to Brosset, 1987). With increasing air volume such systems clearly approach a steady state. Earlier it has been shown that Hg in water is oxidized by O3 primarily

Cyrill Brosset; Elsmari Lord

1995-01-01

17

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

18

Sulfuric acid on Europa and the radiolytic sulfur cycle.  

PubMed

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. PMID:10506568

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

1999-10-01

19

Sulfuric acid spills in marine accidents  

SciTech Connect

Concentrated sulfuric acid and oleum are among the most potentially hazardous chemicals routinely transported in bulk quantities on US and international waterways. Conceivably, during a marine mishap, tons of sulfuric acid could be abruptly released into the water, and the consequences of such a spill could be detrimental to man and the environment. Several acid spill scenarios are briefly described, and the results from laboratory experiments designed to simulate two different types of acid spill accidents are reported. It is shown that the convective mixing of concentrated sulfuric acid with water can adequately be described by a mathematical model which takes into account the variation of the buoyancy force arising from changes in acid concentration and released heat of dilution. A value of 0.21 is determined to be the entrainment parameter for the mixing of sulfuric acid with water. For oleum spills in which acid aerosol formation is a potential safety hazard, a conservative estimate of less than one-tenth of a percent is obtained for the amount of airborne acid under most accident conditions. The fraction of airborne acid, however, decreases very rapidly with increasing release depth below water surfaces. The acid aerosols exhibit a well-defined log-normal particle-size distribution with peak diameter varying from 0.1 to 0.6 ..mu..m (at 70% R.H.) depending upon release depth. This is well within the respirable particle size range.

Tang, I N; Wong, W T; Munkelwitz, H R; Flessner, M F

1980-07-01

20

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

NASA Astrophysics Data System (ADS)

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

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

1999-09-01

21

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 (Bakers 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; Brbel Hahn-Hgerdal; Charlotte Tengborg; Kerstin Stenberg; Guido Zacchi; Nils-Olof Nilvebrant

1999-01-01

22

Dilute acid pretreatment of lignocellulose for whole slurry ethanol fermentation.  

PubMed

Dilute sulfuric acid pretreatment of oil palm empty fruit bunches (EFB) followed by the whole slurry fermentation of the pretreated EFB slurry was investigated. The optimized pretreatment conditions were at 1% (w/v) sulfuric acid with 3 min ramping to 190 C in a microwave digester. Pretreated and washed EFB exhibited enzymatic digestibility of 88.5% of theoretical glucose yield after 48 h of hydrolysis. When the whole slurry of pretreated and neutralized EFB was used in simultaneous saccharification and fermentation (SSF) using cellulase and Saccharomyces cerevisiae, sulfuric acid-pretreated EFB resulted in 52.5% of theoretical ethanol yield based on total glucan in the untreated initial EFB after 72 h of SSF. When pretreated EFB slurry was treated with activated carbon before subjecting to SSF, the SSF furnished 87.5% ethanol yield based on the initial glucan content in untreated EFB (after 48 h of SSF). PMID:23395763

Jung, Young Hoon; Kim, In Jung; Kim, Hyun Kyung; Kim, Kyoung Heon

2013-01-03

23

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

SciTech Connect

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

Wilmarth, W.R.

2000-08-29

24

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

PubMed

A pretreatment strategy for dilute H2SO4 pretreatment of corn stover was developed for the purpose of reducing the generation of inhibitory substances during pretreatment so that a detoxification step is not required prior to fermentation while maximizing sugar yield. The optimal conditions for pretreatment of corn stover (10%, w/v) were: 0.75% H2SO4, 160C, and 0-5 min holding time. The conditions were chosen based on maximum glucose release after enzymatic hydrolysis, minimum loss of pentose sugars and minimum formation of sugar degradation products such as furfural and hydroxymethyl furfural. The pretreated corn stover after enzymatic saccharification generated 63.2 2.2 and 63.7 2.3 g total sugars per L at 0 and 5 min holding time, respectively. Furfural production was 0.45 0.1 and 0.87 0.4 g/L, respectively. The recombinant Escherichia coli strain FBR5 efficiently fermented non-detoxified corn stover hydrolyzate if the furfural content is <0.5 g/L. PMID:23747442

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

2013-05-10

25

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

PubMed

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

Shibata, Manabu; Sakaida, Hideaki; Kakiuchi, Takashi

2010-12-03

26

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. Siz; A. Navarro; P. Soriano; F. Sez; J. M. Martinez

1994-01-01

27

46 CFR 153.1046 - Sulfuric acid.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping...Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

2011-10-01

28

46 CFR 153.1046 - Sulfuric acid.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Sulfuric acid. 153.1046 Section 153.1046 Shipping...Cargo Procedures § 153.1046 Sulfuric acid. No person may liquefy frozen or congealed sulfuric acid other than by external tank heating...

2012-10-01

29

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

NASA Astrophysics Data System (ADS)

We report laboratory studies on the 0.8 MeV proton irradiation of ices composed of sulfuric acid (H 2SO 4), sulfuric acid monohydrate (H 2SO 4H 2O), and sulfuric acid tetrahydrate (H 2SO 44H 2O) between 10 and 180 K. Using infrared spectroscopy, we identify the main radiation products as H 2O, SO 2, (S 2O 3) x, H 3O +, HSO4-, and SO42-. At high radiation doses, we find that H 2SO 4 molecules are destroyed completely and that H 2SO 4H 2O is formed on subsequent warming. This hydrate is significantly more stable to radiolytic destruction than pure H 2SO 4, falling to an equilibrium relative abundance of 50% of its original value on prolonged irradiation. Unlike either pure H 2SO 4 or H 2SO 4H 2O, the loss of H 2SO 44H 2O exhibits a strong temperature dependence, as the tetrahydrate is essentially unchanged at the highest irradiation temperatures and completely destroyed at the lowest ones, which we speculate is due to a combination of radiolytic destruction and amorphization. Furthermore, at the lower temperatures it is clear that irradiation causes the tetrahydrate spectrum to transition to one that closely resembles the monohydrate spectrum. Extrapolating our results to Europa's surface, we speculate that the variations in SO 2 concentrations observed in the chaotic terrains are a result of radiation processing of lower hydration states of sulfuric acid and that the monohydrate will remain stable on the surface over geological times, while the tetrahydrate will remain stable in the warmer regions but be destroyed in the colder regions, unless it can be reformed by other processes, such as thermal reactions induced by diurnal cycling.

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

2011-09-01

30

Charles H. Winston and Confederate Sulfuric Acid  

NASA Astrophysics Data System (ADS)

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

Reithmiller, Steven

1995-07-01

31

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 ...

32

Sulfuric Acid Regeneration Waste Disposal Technology.  

National Technical Information Service (NTIS)

All U.S. Army Ammunition Plants (AAPs) having sulfuric acid regeneration (SAR) facilities use lime precipitation as the principal means of acid wastewater neutralization. This is as an advanced system as is used in industrial practice. However, lime preci...

A. A. Balasco D. E. Johnson J. J. Stahr J. I. Stevens M. A. Fields

1986-01-01

33

Two-stage dilute acid prehydrolysis of biomass.  

National Technical Information Service (NTIS)

The invention relates to a two stage dilute acid prehydrolysis of biomass for solubilization of hemicellulosic sugars and a pretreatment for enzymatic hydrolysis of cellulose. In particular, the invention pertains to a two stage dilute acid prehydrolysis ...

K. Grohmann R. W. Torget

1991-01-01

34

Enzymatic saccharification and fermentation of xylose-optimized dilute acid-treated lignocellulosics  

Microsoft Academic Search

The cellulose reactivity of two lignocellulosic feedstocks, switchgrass and poplar, was evaluated under straight saccharification\\u000a (SS) and simultaneous saccharification and fermentation (SSF) conditions following dilute sulfuric acid pretreatments designed\\u000a for optimum xylose yields. The optimum pretreatment conditions, within the constraints of the experimental system (Parr batch\\u000a reactor), were 1.2% acid, 180C, and 0.5 min for switchgrass and 1% acid, 180C,

Yun-Chin Chung; Alan Bakalinsky; Michael H. Penner

2005-01-01

35

Enzymatic Saccharification and Fermentation of Xylose-Optimized Dilute Acid-Treated Lignocellulosics  

Microsoft Academic Search

The cellulose reactivity of two lignocellulosic feedstocks, switchgrass and poplar, was evaluated under straight saccharification\\u000a (SS) and simultaneous saccharification and fermentation (SSF) conditions following dilute sulfuric acid pretreatments designed\\u000a for optimum xylose yields. The optimum pre-treatment conditions, within the constraints of the experimental system (Parr batch\\u000a reactor), were 1.2% acid, 180C, and 0.5 min for switchgrass and 1% acid, 180C,

Yun-Chin Chung; Alan Bakalinsky; Michael H. Penner

36

Process for Producing Sulfurous Acid Treated Alumina.  

National Technical Information Service (NTIS)

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

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

1964-01-01

37

Sulfuric acid/hydrogen peroxide rinsing study  

SciTech Connect

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

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

1995-12-01

38

Infrared spectroscopy of sulfuric acid/water aerosols: Freezing characteristics  

NASA Astrophysics Data System (ADS)

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

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

1997-04-01

39

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

Microsoft Academic Search

The performance of two pretreatment methods, sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) and dilute acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production at 180C for 30min with a sulfuric acid loading of 5% on oven-dry wood and a 5:1 liquor-to-wood ratio. SPORL was supplemented with 9% sodium sulfite (w\\/w of wood). The recoveries of

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

2010-01-01

40

CONSTRUCTION OF A PROTOTYPE SULFURIC ACID MIST MONITOR  

EPA Science Inventory

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

41

Sulfur Acidity Loading in South Korean Ecosystems  

Microsoft Academic Search

The applicability of critical load (CL) methodology for thedetermination of natural terrestrial ecosystem sensitivity to sulfur acidity loading in South Korea was investigated.The sulfur critical load values, CLmaxS, were calculated for the terrestrial ecosystems of South Korea using the steady-state mass balance approach. The corresponding mapping of CLmaxS was carried out on the scale of 11 14 km grid

Soon-Ung Park; Vladimir Bashkin

2001-01-01

42

Determination of Hazardous Elements in Smelter-Produced Sulfuric Acid.  

National Technical Information Service (NTIS)

The report presents results of analyses of potentially hazardous impurities (trace elements) in sulfuric acid produced by non-ferrous smelters. Sulfuric acid samples were obtained from acid plants attached to copper, lead, and zinc smelters. Results of an...

W. H. Hedley S. M. Mehta P. L. Sherman

1974-01-01

43

Growth of nitric acid hydrates on thin sulfuric acid films  

NASA Astrophysics Data System (ADS)

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 10-4 Torr H2O and 1 - 2.5 10-6 Torr HNO3) and subjected to cooling and heating cycles. 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.

1994-05-01

44

Growth of nitric acid hydrates on thin sulfuric acid films  

Microsoft Academic Search

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-310-4 Torr H2O and 1-2.510-6 Torr HNO3) and subjected to cooling and heating cycles. FTIR spectroscopy was used to probe the phase of the sulfuric acid and

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

1994-01-01

45

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

Microsoft Academic Search

A series of three pressurized sulfuric acid decomposition tests were performed to (1) obtain data on the fraction of sulfuric acid catalytically converted to sulfur dioxide, oxygen, and water as a function of temperature and pressure, (2) demonstrate real-time measurements of acid conversion for use as process control, (3) obtain multiple measurements of conversion as a function of temperature within

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

2005-01-01

46

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

47

The Electrochemical Behavior of Armco Iron in Sulfuric Acid.  

National Technical Information Service (NTIS)

The polarization behavior of Armco iron in sulfuric acid solutions was investigated. Anodic and cathodic polarization curves were obtained using aerated and deaerated solutions of 1N and pH1 sulfuric acid by galvanostatic and potentiostatic methods. (Auth...

H. A. Porte T. E. Nappier

1964-01-01

48

Sulfuric Acid Spill Characteristics under Maritime Accident Conditions.  

National Technical Information Service (NTIS)

Concentrated sulfuric acid and oleum are among the most potentially hazardous chemicals routinely transported in bulk quantities on U.S. and international waterways. Conceivably, during a marine mishap, tons of sulfuric acid could abruptly be released int...

G. S. Smith H. R. Munkelwitz I. N. Tang W. T. Wong

1981-01-01

49

Activities and vapor pressures of aqueous sulfuric acid solutions  

Microsoft Academic Search

A quantitative interpretation of the conditions leading to the formation of sulfuric acid in whatever system requires the knowledge of the thermodynamic properties of aqueous sulfuric acid solutions under the conditions of temperature and partial pressures at which the liquid phase is likely to nucleate. Surprisingly, in the light of the importance of sulfuric acid in industrial technology, such data

Bolsaitis

1986-01-01

50

Heterogeneous interaction of peroxyacetyl nitrate with liquid sulfuric acid  

Microsoft Academic Search

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

Renyi Zhang; Ming-Taun Leu

1997-01-01

51

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

Microsoft Academic Search

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

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

2004-01-01

52

Hydrate sulfuric acid after sulfur implantation in water ice  

Microsoft Academic Search

For many years an ongoing research program performed at our laboratory has had the aim to investigate the implantation of reactive ions in ices relevant to planetology by using IR spectroscopy. We present new results obtained by implanting 200 keV sulfur ions into water ice at 80 K. We have looked at the formation of sulfur-bearing molecules such as sulfuric

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

2007-01-01

53

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

54

Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium  

ERIC Educational Resources Information Center

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

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

2005-01-01

55

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

56

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

Code of Federal Regulations, 2011 CFR

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

2012-10-01

57

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. Mller-Steinhagen; D. Lancefield

2007-01-01

58

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

Microsoft Academic Search

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

Durlubh K. Sharma; Irving S. Goldstein

1990-01-01

59

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

SciTech Connect

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

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

2009-01-01

60

Effects of Two-Stage Dilute Acid Pretreatment on the Structure and Composition of Lignin and Cellulose in Loblolly Pine  

Microsoft Academic Search

A standard two-step dilute sulfuric acid pretreatment was performed on Loblolly pine to enhance the overall efficiency of\\u000a enzymatic deconstruction of woody biomass to monomeric sugars. The structure of milled wood lignin and cellulose isolated\\u000a from the untreated and acid-treated biomass was studied in detail. Solid-state 13C NMR spectroscopy coupled with line shape analyses has been employed to elucidate cellulose

Poulomi Sannigrahi; Arthur J. Ragauskas; Stephen J. Miller

2008-01-01

61

Growth of nitric acid hydrates on thin sulfuric acid films  

Microsoft Academic Search

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 [times] 10[sup [minus]4] Torr H[sub 2]O and 1-2.5 [times] 10[sup [minus]6] Torr HNO[sub 3]) and subjected to cooling and heating cycles. FTIR spectroscopy was used to

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

1994-01-01

62

Growth of nitric acid hydrates on thin sulfuric acid films  

Microsoft Academic Search

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1 - 3 10?4 Torr H2O and 1 - 2.5 10?6 Torr HNO3) and subjected to cooling and heating cycles. FTIR spectroscopy was used to

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

1994-01-01

63

Biological sulfuric acid transformation: Reactor design and process optimization  

Microsoft Academic Search

As an alternative to the current disposal technologies for waste sulfuric acid, a new combination of recycling processes was developed. The strong acid (H[sub 2]SO[sub 4]) is biologically converted with the weak acid (CH[sub 3]COOH) into two volatile weak acids (H[sub 2]S, H[sub 2]CO[sub 3]) by sulfate-reducing bacteria. The transformation is possible without prior neutralization of the sulfuric acid. The

Gerhard Stucki; R. A. Huerzeler; K. W. Hanselmann

1993-01-01

64

Parametric study of sulfuric acid decomposer for hydrogen production  

Microsoft Academic Search

It is proposed to use a ceramic high-temperature heat exchanger as a sulfuric acid decomposer for hydrogen production within the sulfuriodine thermo-chemical cycle portion of the hydrogen production process. In this cycle, hot helium from a nuclear reactor is used to heat the SI (sulfuric acid) feed components (H2O, H2SO4, SO3) to obtain appropriate conditions for the SI decomposition reaction.

Valery Ponyavin; Yitung Chen; Taha Mohamed; Mohamed Trabia; Anthony E. Hechanova; Merrill Wilson

2008-01-01

65

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 ...

66

Solubility of HCL in sulfuric acid at stratospheric temperatures  

NASA Astrophysics Data System (ADS)

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.

1993-10-01

67

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...

68

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

69

46 CFR 151.50-21 - Sulfuric acid.  

Code of Federal Regulations, 2011 CFR

...acceptable means of liquefying frozen or congealed sulfuric acid. (c) During cargo transfer, a water hose shall be connected to a water supply ready for immediate use and any leakage or spillage of acid shall be immediately washed down. This...

2011-10-01

70

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

National Technical Information Service (NTIS)

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

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

1969-01-01

71

Recovery of very dilute acetic acid using ion exchange  

SciTech Connect

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

Cloete, F.L.D.; Marais, A.P. [Univ. of Stellenbosch (South Africa). Dept. of Chemical Engineering

1995-07-01

72

Surface Chemical Properties of Liquid Sulfuric Acid in Ultrahigh Vacuum  

NASA Astrophysics Data System (ADS)

Chemical reactions that occur in the surface and near surface regions of sulfate aerosol particles are of importance in the troposphere and stratosphere. With the goal of gaining insight into how these reactions occur, we have examined the surface chemical properties of ultrathin (10-100 monolayers thick) films of sulfuric acid in ultrahigh vacuum. The films are grown via the reaction of co-condensed multilayers of sulfur trioxide and water on a Pt(111) substrate. Film composition can be varied from approximately 10 mole percent to >95 percent sulfuric acid. Concentrated films can be prepared as crystalline solids, amorphous solids, and liquids. The surface chemical properties of the amorphous solid and liquid films will be compared. Among the molecules whose interactions with liquid and solid sulfuric acid will be discussed are hydrogen chloride (HCl), a substance of considerable atmospheric relevance, and isopropanol, which is decomposed by sulfuric acid to form water and propene.

Roberts, Jeffrey; Schindler, Liesl; Guldan, Elizabeth

1996-03-01

73

Tribocorrosion of stainless steel in sulfuric acid: Identification of corrosionwear components and effect of contact area  

Microsoft Academic Search

Electrochemical and friction measurements during unidirectional sliding tests are used to monitor and to evaluate the tribocorrosion behavior of a passivating material. Tribocorrosion is the interplay between chemical, electrochemical, and mechanical processes leading to a degradation of materials immersed in a corrosive environment. The tribocorrosion of AISI 316 stainless steel immersed in a diluted sulfuric acid solution at 25C was

N. Diomidis; J.-P. Celis; P. Ponthiaux; F. Wenger

2010-01-01

74

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, 96.5C and 138min), 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, Ins C; Snchez, Sebastin; Moya, Alberto J

2013-09-20

75

Sulfuric acid monohydrate: Formation and heterogeneous chemistry in the stratosphere  

Microsoft Academic Search

We have investigated some thermodynamic properties (i.e., freezing\\/melting points) and heterogeneous chemistry of sulfuric acid monohydrate (SAM, H2SO4.H2O), using a fast flow reactor coupled to a quadrupole mass spectrometer. The freezing point observations of thin liquid sulfuric acid films show that for acid contents between 75 and 85 wt% the monohydrate crystallizes readily at temperatures between 220 and 240 K

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

1995-01-01

76

Lack of bronchoconstrictor response to sulfuric acid aerosols and fogs  

Microsoft Academic Search

Sulfuric acid (HSO) is the most common acid air pollutant in the United States and is thought to have adverse respiratory effects. Sulfuric acid exists in polluted air as a dissolved solute in both small (haze) and large (fog) particles. Previous work in our laboratory has failed to demonstrate bronchoconstriction after near ambient, large-particle HSO exposure in subjects with asthma.

R. Aris; D. Christian; D. Sheppard; J. R. Balmes

1991-01-01

77

Short-Term Respiratory Effects of Sulfuric Acid in Fog: A Laboratory Study of Healthy and Asthmatic Volunteers  

Microsoft Academic Search

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 (?0.1 g\\/m liquid water content, 10 ?m median droplet diameter, 10C) containing nominally 0, 500, 1000, and 2000 ?g\\/m of sulfuric acid. Fog was produced by atomizing dilute acid solution Into purified air humidified

Edward L. Avol; William S. Linn; Leonard H. Wightman; Jill D. Whynot; Karen R. Anderson; Jack D. Hackney

1988-01-01

78

Integrated boiler, superheater, and decomposer for sulfuric acid decomposition  

DOEpatents

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

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

2010-01-12

79

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...

80

Breakdown of cell wall nanostructure in dilute acid pretreated biomass.  

PubMed

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

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

2010-09-13

81

Dietary sulfur amino acid modulation of cysteine sulfinic acid decarboxylase.  

PubMed

Male rats were fed sulfur and nonsulfur amino acid-supplemented diets, and the response of cysteine sulfinic acid decarboxylase (CSAD) activity was determined. After adaptation to a casein-based basal diet, rats were fed diets containing additions of L-methionine. Hepatic CSAD activity decreased in a dose-dependent manner. Significant depression of CSAD activity in liver was evident within 24 h of feeding rats a methionine-supplemented diet. Depression of enzyme activity was reversed upon refeeding the basal diet. After rats were fed diets supplemented with methionine, cystine, homocystine, S-methyl-L-cysteine, phenylalanine, leucine, or ethionine for 14 days, hepatic CSAD activity in rats fed S-methyl-L-cysteine-, phenylalanine-, or leucine-supplemented diets was not depressed compared with activity in rats fed a basal diet. In contrast, CSAD activity in livers of rats fed cystine-, homocystine-, methionine-, or ethionine-supplemented diets was 60, 40, 40, and 8%, respectively, of the activity in livers from control rats. Immunochemical detection and quantification of CSAD protein in rat liver indicated that CSAD protein concentration was correlated to CSAD activity. CSAD activity may be specifically regulated by sulfur amino acids metabolized by the S-adenosylmethionine-dependent pathway of methionine metabolism. PMID:1951678

Jerkins, A A; Steele, R D

1991-11-01

82

Opacity of monodisperse sulfuric acid aerosols  

NASA Astrophysics Data System (ADS)

The plume opacity and droplet diameters of a monodisperse sulfuric acid aerosol were calculated as a function of the initial H 2SO 4 concentration, initial H 2O concentration and final gas temperature after cooling from an original stack gas temperature of 300C. Calculation assumptions include heterogeneous heteromolecular condensation of H 2SO 4 and H 2O onto monodisperse nuclei of 0.05 ?m dia., three aerosol particle nuclei concentrations of 10 6, 10 7 and 10 8 cm -3 (at 300C and 760 mm Hg); and a stack or plume diameter of 6 m. The calculated results show that for the conditions considered and with the stack temperatures in excess of 125C, initial H 2SO 4 stack gas concentrations of 10ppm or less will result in calculated opacities of less than 20 % for a plume diameter of 6 m. The results show that the calculated opacity is significantly affected by the initial H 2SO 4 and initial H 2O concentrations and the final gas temperature. The increases in the calculated opacities upon cooling of the stack gases are similar in general to the increases in the measured opacities between instack and outstack reported by Nader and Conner (1978) for an oil-fired boiler.

Pilat, Michael J.; Wilder, James M.

83

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

PubMed

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

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

2012-01-12

84

Sulfuric acid aerosols in the atmospheres of the terrestrial planets  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

85

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

PubMed

This study investigated the effects of pretreatment conditions, dilute sulfuric acid concentration and treatment time, on the carbohydrate solubility of a mixture of barley straw and grain. The conditions were expressed as combined severity (CS) to evaluate sugar recovery from pretreated samples. Enzymatic hydrolysates from the lignocellulose pretreatment residues were also included to the results. CS was positively correlating with glucose recovery in all conditions, but in higher acid concentrations CS did not predict xylose recovery. It appeared that the residual xylan better indicate the xylose release. An optimal fermentable sugar yield from the mixture of barley straw and grain was obtained by maintaining the CS at around 1.38, corresponding to an overall glucose yield of 96% and a xylose yield of 57%. PMID:23955092

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

2013-07-30

86

Investigation of the thermal decomposition of sulfuric acid containing inorganic impurities  

SciTech Connect

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

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

1986-09-20

87

Interaction of two oscillating sonoluminescence bubbles in sulfuric acid.  

PubMed

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

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

2010-07-29

88

Sulfuric Acid-Induced Corrosion of Aluminum Surfaces.  

National Technical Information Service (NTIS)

The sulfuric acid-induced corrosion of smooth (2 nm average roughness) aluminum surfaces has been studied in real times using an in situ Fourier transform infrared reflection absorption spectrometer and a quartz crystal microbalance. Submicron thick, 35 t...

Q. Dai A. Freedman G. N. Robinson

1995-01-01

89

Uptake kinetics of three epoxides into sulfuric acid solution  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

90

Surface Tensions and Densities of Sulfuric Acid + Dimethylamine + Water Solutions  

Microsoft Academic Search

The surface tensions and densities of aqueous solutions of dimethylamine, (CH3)2NH, and sulfuric acid, H2SO4, were measured at 24.2 C. Mol fractions of dimethylamine were varied between 0 and 0.21 and of sulfuric acid between 0 and 0.48. The surface tension of the binary dimethylamine + water solution decreased exponentially as dimethylamine was added, from the surface tension of water

Heikki Lihavainen; Kaisa Hautio; Tomi Raatikainen; Ari Laaksonen; Yrj Viisanen

2004-01-01

91

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

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

Gary M. Blythe

2002-01-01

92

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2002 through March 31, 2003. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of

Gary M. Blythe

2003-01-01

93

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

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

Gary M. Blythe

2001-01-01

94

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

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

Gary M. Blythe

2003-01-01

95

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

Microsoft Academic Search

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

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

1990-01-01

96

Two-stage pretreatment of rice straw using aqueous ammonia and dilute acid.  

PubMed

Liberation of fermentable sugars from recalcitrant lignocellulosic biomass is one of the key challenges in production of cellulosic ethanol. Here we developed a two-stage pretreatment process using aqueous ammonia and dilute sulfuric acid in a percolation mode to improve production of fermentable sugars from rice straw. Aqueous NH? was used in the first stage which removed lignin selectively but left most of cellulose (97%) and hemicellulose (77%). Dilute acid was applied in the second stage which removed most of hemicellulose, partially disrupted the crystalline structure of cellulose, and thus enhanced enzymatic digestibility of cellulose in the solids remaining. Under the optimal pretreatment conditions, the enzymatic hydrolysis yields of the two-stage treated samples were 96.9% and 90.8% with enzyme loadings of 60 and 15FPU/g of glucan, respectively. The overall sugar conversions of cellulose and hemicellulose into glucose and xylose by enzymatic and acid hydrolysis reached 89.0% and 71.7%, respectively. PMID:21784629

Kim, Jin-Woo; Kim, Kyoung Seob; Lee, Jin-Suk; Park, Sung Min; Cho, Hwa-Young; Park, Jae Chan; Kim, Jun Seok

2011-06-23

97

Photometric determination of sulfuric acid in ammonium sulfate  

SciTech Connect

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

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

1982-01-01

98

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

99

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

100

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

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

Cellulase Accessibility of Dilute-Acid Pretreated Corn Stover  

SciTech Connect

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

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

2005-01-01

103

Photolysis of sulfuric acid vapor by visible solar radiation.  

PubMed

Atmospheric field measurements and models of the stratospheric sulfate aerosol layer led to the suggestion that sulfuric acid (H2SO4) must photolyze at high altitudes. We propose that excitation of vibrational overtones of H2SO4 and its hydrate in the near-infrared and visible leads to photolysis, forming sulfur trioxide (SO3) and water. On the basis of absorption cross sections calculated with ab initio methods calibrated to experimental measurements, we estimated J values that are sufficient to explain stratospheric and mesospheric sulfur dioxide (SO2) concentrations and the observation of the sulfate layer. PMID:12624265

Vaida, V; Kjaergaard, H G; Hintze, P E; Donaldson, D J

2003-03-01

104

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

105

21 CFR 184.1095 - Sulfuric acid.  

Code of Federal Regulations, 2013 CFR

...oxide (NO) with sulfur dioxide and water. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981), pp. 317-318, which is incorporated by reference. Copies may be obtained from the National Academy...

2013-04-01

106

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...

107

Elemental sulfur dynamics in acid sulfate soil landscapes  

Microsoft Academic Search

The precipitation and dissolution of iron and sulfur minerals has a primary influence on water quality of acid sulfate affected landscapes (Fanning et al. 2002; Nordstrom 2000). The two key processes involved are the microbially mediated reduction and oxidation of sulfate and iron (Peine et al. 2000), which drive the geochemical store and flux of acidity. Iron sulfide minerals are

Richard T Bush; Edward D Burton; Leigh A Sullivan; Salirian R Claff

2006-01-01

108

EVALUATION OF METHODOLOGY AND PROTOTYPE TO MEASURE ATMOSPHERIC SULFURIC ACID  

EPA Science Inventory

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

109

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...

110

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...

111

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

SciTech Connect

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

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

2005-09-01

112

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

113

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; Daz, Manuel J; Cara, Cristbal; Ruiz, Encarnacin; Romero, Inmaculada; Moya, Manuel

2010-08-22

114

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

NASA Astrophysics Data System (ADS)

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

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

1990-07-01

115

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

PubMed

In this research, a recombinant whole cell biocatalyst was developed by expressing three cellulases from Clostridium cellulolyticum--endoglucanase (Cel5A), exoglucanase (Cel9E), and ?-glucosidase--on the surface of the Escherichia coli LY01. The modified strain is identified as LY01/pRE1H-AEB. The cellulases were displayed on the surface of the cell by fusing with an anchor protein, PgsA. The developed whole cell biocatalyst was used for single-step ethanol fermentation using the phosphoric acid-swollen cellulose (PASC) and the dilute acid-pretreated corn stover. Ethanol production was 3.59 0.15 g/L using 10 g/L of PASC, which corresponds to a theoretical yield of 95.4 0.15%. Ethanol production was 0.30 0.02 g/L when 1 g/L equivalent of glucose in the cellulosic fraction of the dilute sulfuric acid-pretreated corn stover (PCS) was fermented for 84 h. A total of 0.71 0.12 g/L ethanol was produced in 48 h when the PCS was fermented in the simultaneous saccharification and co-fermentation mode using the hemicellulosic (1 g/L of total soluble sugar) and as well as the cellulosic (1 g/L of glucose equivalent) parts of PCS. In a control experiment, 0.48 g/L ethanol was obtained from 1 g/L of hemicellulosic PCS. It was concluded that the whole cell biocatalyst could convert both cellulosic and hemicellulosic substrates into ethanol in a single reactor. The developed C. cellulolyticum-E. coli whole cell biocatalyst also overcame the incompatible temperature problem of the frequently reported fungal-yeast systems. PMID:21519935

Ryu, Seunghyun; Karim, Muhammad Nazmul

2011-04-26

116

Adhesion of polypropylene treated with nitric and sulfuric acid  

Microsoft Academic Search

The surface treatment of polyolefins to improve its adhesion capacity remains as an important field of research and several techniques are described in the literature. In this work, we are interested in the development of a method to obtain adherent polypropylene. In this way, we investigate the effect of nitric and sulfuric acid treatments onto polymer plates under various experimental

Anamlia S. Vasconcellos; Joo A. P. Oliveira; Ricardo Baumhardt-Neto

1997-01-01

117

Hydrogen peroxide in sulfuric acid extraction of uranium ores  

Microsoft Academic Search

Uranium can be extracted from its ores at a pH of 2.5 to 5.5 using sulfuric acid, hydrogen peroxide, trace of iron and a sulfate. The extraction process is applicable to both tank leaching of conventionally mined ores and in situ leaching.

DeVries

1984-01-01

118

Electrosynthesis of anisidines in aqueous sulfuric and acetic acids  

NASA Astrophysics Data System (ADS)

The influence of the concentrations of acetic and sulfuric acids on the efficiency of anisole amination by means of hydroxylamine and Ti(IV)/Ti(III) mediator was studied. Ortho- and para-anisidines were obtained with the total yields of about 79% by current and hydroxylamine.

Lisitsyn, Yu. A.; Grigor'eva, L. V.

2009-03-01

119

Thermal Regeneration of Sulfuric Acid Hydrates after Irradiation.  

National Technical Information Service (NTIS)

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 a...

M. J. Loeffler R. L. Hudson

2012-01-01

120

Sulfuric Acid and Ferrous Sulfate Recovery from Waste Pickle Liquor.  

National Technical Information Service (NTIS)

A bath bar pickler and a bath rod pickler are used for cleaning 40,000 tons per year of cold-rolled steel using sulfuric acid at the Fitzsimons Steel Company's Youngstown, Ohio plant. A facility for the treatment of the spent pickle liquor including rinse...

J. K. Seyler W. E. Thornton M. K. Householder

1974-01-01

121

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...

122

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 ...

123

Hydrogen peroxide in sulfuric acid extraction of uranium ores  

SciTech Connect

Uranium can be extracted from its ores at a pH of 2.5 to 5.5 using sulfuric acid, hydrogen peroxide, trace of iron and a sulfate. The extraction process is applicable to both tank leaching of conventionally mined ores and in situ leaching.

DeVries, F.W.

1984-01-10

124

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

125

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

126

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

127

Vapor pressures in the ternary system water-nitric acid-sulfuric acid at low temperatures  

SciTech Connect

The partial vapor pressures over liquid or supercooled solutions of water and nitric acid and of water and sulfuric acid are calculated for temperatures below 0C. From these results the partial vapor pressures over the ternary system water-nitric acid-sulfuric (liquid or supercooled) have been estimated and compared with the available experimental data of Vandoni at 0C. Some possible implications for the formation of stratospheric aerosols are also discussed.

Jaecker-Voirol, A.; Ponche, J.L.; Mirabel, P. (Universite Louis Pasteur, Strasbourg (France))

1990-07-20

128

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

129

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Sulfuric acid; exemption from the requirement of a tolerance...From Tolerances § 180.1019 Sulfuric acid; exemption from the requirement of a tolerance. (a) Residues of sulfuric acid are exempted from the requirement...

2013-07-01

130

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

Microsoft Academic Search

Data from exposure of experimental animals and human subjects to sulfuric acid presents a consistent picture of its toxicology. Effects on airway resistance in asthmatic subjects were well predicted by data obtained on guinea pigs. Sulfuric acid increases the irritant response to ozone in both rats and man. In donkeys, rabbits, and human subjects, sulfuric acid alters clearance of particles

Amdur

1989-01-01

131

Hybrid reactive distillation systems for n-butyl acetate production from dilute acetic acid  

Microsoft Academic Search

The recovery of dilute acetic acid, regarding as a waste stream in many chemical and petrochemical processes, becomes an important issue due to economic and environmental awareness. In this work, a simulation study on the direct utilization of dilute acetic acid to produce n-butyl acetate via esterification with butanol in a reactive distillation is presented by using Aspen Plus. The

Amornchai Arpornwichanop; Kittipong Koomsup; Suttichai Assabumrungrat

2008-01-01

132

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

PubMed

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

2013-01-15

133

Effect of sulfuric acid in wood plastic composite  

NASA Astrophysics Data System (ADS)

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

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

1996-01-01

134

Mechanism of acidity generation on sulfur-promoted metal oxides  

SciTech Connect

The effect of sulfur promotion on the generation of strong acidity on ZrO/sub 2/, TiO/sub 2/, Fe/sub 2/O/sub 3/, Al/sub 2/O/sub 3/, SnO/sub 2/, SiO/sub 2/, and Bi/sub 2/O/sub 3/ was examined by the isomerization of cyclopropane and by infrared spectroscopy. The acidity generated varied on the types of oxides. The highest promotion effect was found in the cases of ZrO/sub 2/, TiO/sub 2/, and Fe/sub 2/O/sub 3/, while a lower effect was observed for Al/sub 2/O/sub 3/ and SnO/sub 2/, and no effect was found for SiO/sub 2/ and Bi/sub 2/O/sub 3/. Infrared spectroscopic observation indicates the presence of the surface sulfur complex having covalent SO double bonds on all of the sulfur-promoted oxides. An admission of pyridine resulted in a remarkable shift in an asymmetric stretching frequency of S=O bonds in the cases of ZrO/sub 2/, TiO/sub 2/, and Fe/sub 2/O/sub 3/; however, a small shift was found on Al/sub 2/O/sub 3/, and no shift was found on SiO/sub 2/ and Bi/sub 2/O/sub 3/. The magnitude of this shift was well-correlated with the extent of the promotion effect. The drastic shift suggests that a change of electronic structure in the surface sulfur complex takes place by the adsorption of basic molecules. The origin of the generation of the strong acidity by a sulfur promotion is the formation of the surface sulfur complex which has a covalent SO double bond on one hand and a strong tendency of losing its double-bond character or decreasing the bond order of SO by an electronic shift from a basic molecule adsorbed to the sulfur complex on the other.

Jin, T.; Yamaguchi, T.; Tanabe, K.

1986-09-25

135

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

EPA Science Inventory

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

136

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

137

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

138

Infrared spectroscopy of sulfuric acid\\/water aerosols: Freezing characteristics  

Microsoft Academic Search

A low-temperature flow cell has been used in conjunction with a Fourier transform infrared (FT-IR) spectrometer to study sulfuric acid\\/water aerosols. The aerosols were generated with a wide range of composition (28 to 85 wt %), including those characteristic of stratospheric sulfate aerosols, and studied over the temperature range from 240 K to 160 K. The particles exhibited deep supercooling,

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

1997-01-01

139

A critique of homogeneous freezing measurements of aqueous sulfuric acid  

NASA Astrophysics Data System (ADS)

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

Alofs, Darryl J.; Vandike, John L.

2000-08-01

140

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...

141

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

142

Dilute oxalic acid pretreatment for biorefining giant reed (Arundo ...  

Treesearch

Description: Biomass pretreatment is essential to overcome recalcitrance of ... ( Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic ... giant reed, Arundo donax, pretreatment, biomass, utilization, biomass energy,...

143

Electrochemical behavior of graphite in electrolyte of sulfuric and acetic acid  

Microsoft Academic Search

Electrochemical formation of graphite intercalation compounds (GICs) has been studied in the electrolyte with mixed sulfuric acid and acetic acid. The results show that, with addition of acetic acid, GICs can be synthesized in the electrolyte with sulfuric acid concentration as low as 3.6M, even though no GIC is formed in pure acetic acid. The stage structure of the synthesized

F. Kang; T.-Y. Zhang; Y. Leng

1997-01-01

144

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

145

Sonoluminescence radiation from different concentrations of sulfuric acid  

NASA Astrophysics Data System (ADS)

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

Moshaii, A.; Imani, Kh.; Silatani, M.

2009-10-01

146

Sonoluminescence radiation from different concentrations of sulfuric acid.  

PubMed

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

Moshaii, A; Imani, Kh; Silatani, M

2009-10-30

147

Effects of acid rain and sulfur dioxide on marble dissolution  

SciTech Connect

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

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

1994-01-01

148

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

149

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

PubMed

Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350 C and sulfuric acid loadings from 0.92 to 7.10 wt.%. An optimal LGO yield of 7.58 wt.% was obtained at 270 C with a sulfuric acid pretreatment concentration of 0.05 M (corresponding to 4.28 wt.% sulfuric acid loading). For comparison, microcrystalline cellulose pretreated by 0.05 M sulfuric acid solution was pyrolyzed at temperature from 270 C to 320 C, and bagasse loaded with 3-5 wt.% phosphoric acid was pyrolyzed at temperature from 270 C to 350 C. The highest yield of LGO from bagasse was 30% higher than that from microcrystalline cellulose, and treatment with sulfuric acid allowed a 21% higher yield than treatment with phosphoric acid. PMID:22047659

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

2011-10-12

150

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

151

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

152

Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design  

NASA Astrophysics Data System (ADS)

Increasing global climate change has been driven by greenhouse gases emissions originating from the combustion of fossil fuels. Clean burning hydrogen has the potential to replace much of the fossil fuels used today reducing the amount of greenhouse gases released into the atmosphere. The sulfur iodine and hybrid sulfur thermochemical cycles coupled with high temperature heat from advanced nuclear reactors have shown promise for economical large-scale hydrogen fuel stock production. Both of these cycles employ a step to decompose sulfuric acid to sulfur dioxide. This decomposition step occurs at high temperatures in the range of 825C to 926C dependent on the catalysis used. Successful commercial implementation of these technologies is dependent upon the development of suitable materials for use in the highly corrosive environments created by the decomposition products. Boron treated diamond film was a potential candidate for use in decomposer process equipment based on earlier studies concluding good oxidation resistance at elevated temperatures. However, little information was available relating the interactions of diamond and diamond films with sulfuric acid at temperatures greater than 350C. A laboratory scale sulfuric acid decomposer simulator was constructed at the Nuclear Science and Engineering Institute at the University of Missouri-Columbia. The simulator was capable of producing the temperatures and corrosive environments that process equipment would be exposed to for industrialization of the sulfur iodide or hybrid sulfur thermochemical cycles. A series of boron treated synthetic diamonds were tested in the simulator to determine corrosion resistances and suitability for use in thermochemical process equipment. These studies were performed at twenty four hour durations at temperatures between 600C to 926C. Other materials, including natural diamond, synthetic diamond treated with titanium, silicon carbide, quartz, aluminum nitride, and Inconel were also tested in the simulator to determine corrosion resistances. The study concluded that boron treated diamonds were not suitable for use in decomposer process equipment. Unacceptable corrosion rates were observed at 600C and increased linearly with temperature up to 700C. The boron treated diamonds completely disassociated at temperatures above 700C. The researcher postulated that the high corrosion rates resulted from diamond carbon having a higher preference for oxygen free radicals formed during the decomposition process. Oxygen free radical concentration also increased as a function of increasing temperature. The study also concluded that natural diamond and synthetic titanium treated diamond were unsuitable for use in decomposer process equipment. The corrosion results were similar to that of the boron treated diamonds. Silicon carbide may have potential for used in decomposer process equipment. No appreciable silicon carbide corrosion was observed and more study is warranted. Small amounts of quartz and aluminum nitride corrosion was observed. Inconel corrosion rates were very high at all temperatures tested.

Peck, Michael S.

153

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

154

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

155

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

NASA Astrophysics Data System (ADS)

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 aerosol mass spectrometer (AMS) to probe the uptake of gas-phase hexanal into ammonium sulfate and sulfuric acid aerosols. While both deliquesced and dry non-acidic ammonium sulfate aerosols showed no organic uptake, the acidic aerosols took up substantial amounts of organic material when exposed to hexanal vapor. Further, we used 1H-NMR, Fourier transform infrared (FTIR) spectroscopy and GC-MS to identify the products of the acid-catalyzed reaction of hexanal in acidic aerosols. Both aldol condensation and hemiacetal products were identified, with the dominant reaction products dependent upon the initial acid concentration of the aerosol. The aldol condensation product was formed only at initial concentrations of 75-96 wt% sulfuric acid in water. The hemiacetal was produced at all sulfuric acid concentrations studied, 30-96 wt% sulfuric acid in water. Aerosols up to 88.4 wt% organic/11.1 wt% H 2SO 4/0.5 wt% water were produced via these two dimerization reaction pathways. The UV-VIS spectrum of the isolated aldol condensation product, 2-butyl 2-octenal, extends into the visible region, suggesting these reactions may impact aerosol optical properties as well as aerosol composition. In contrast to previous suggestions, no polymerization of hexanal or its products was observed at any sulfuric acid concentration studied, from 30 to 96 wt% in water.

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

156

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

157

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

Microsoft Academic Search

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

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

2011-01-01

158

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

Microsoft Academic Search

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

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

2012-01-01

159

Dilute Acid Hydrolysis of Cellulose and Cellulosic Bio-Waste Using a Microwave Reactor System  

Microsoft Academic Search

The dilute acid hydrolysis of grass and cellulose with phosphoric acid was undertaken in a microwave reactor system. The experimental data and reaction kinetic analysis indicate that this is a potential process for cellulose and hemi-cellulose hydrolysis, due to a rapid hydrolysis reaction at moderate temperatures. The optimum conditions for grass hydrolysis were found to be 2.5% phosphoric acid at

A. Orozco; M. Ahmad; D. Rooney; G. Walker

2007-01-01

160

Note: Electrochemical etching of silver tips in concentrated sulfuric acid  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

161

A rotamer energy level study of sulfuric acid  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

162

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

163

An ecological survey of the effect of sulfur dioxide emitted from an Acid Work Factory  

Microsoft Academic Search

Sulfur dioxide is che of the most common air pollutants. The acid manufacturing factory ai Ching Lung Tau, Hong Kong has emitted large quantities of sulfur dioxide into the atmosphere since 1955. Sulfur dioxide emitted from the factory moved according to the prevailing wind and dam~ged the surrounding vegetation. Erosion of the top soil followed the death of plants and

Ming-Hung Wong

1978-01-01

164

Reductive desorption of sulfuric acid formed on the carbon catalyst in flue gas desulfurization (FGD)  

Microsoft Academic Search

Reductive desorption of sulfuric acid formed on the carbon catalyst in flue gas desulfurization (FGD) by heating with hydrogen at 3: 200°C converted the acid to gas-phase sulfur dioxide with a significant loss of the acid to hydrogen sulfide and elemental sulfur. These side reactions were suppressed and the temperature required for SO recovery was reduced by impregnating the charcoal

S. Yoshizawa; A. Karagiri; K. Watanabe

1979-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

166

Potential abatement production and marketing of byproduct sulfuric acid in the U. S. Final report, July 1974June 1977  

Microsoft Academic Search

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 disposal and conserve natural sulfur and natural gas used to mine sulfur.) A cost model was

J. I. Bucy; R. L. Torstrick; W. L. Anders; J. L. Nevins; P. A. Corrigan

1978-01-01

167

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

168

Sulfuric acid monohydrate: Formation and heterogeneous chemistry in the stratosphere  

NASA Astrophysics Data System (ADS)

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

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

1995-09-01

169

Lack of bronchoconstrictor response to sulfuric acid aerosols and fogs.  

PubMed

Sulfuric acid (H2SO4) is the most common acid air pollutant in the United States and is thought to have adverse respiratory effects. Sulfuric acid exists in polluted air as a dissolved solute in both small (haze) and large (fog) particles. Previous work in our laboratory has failed to demonstrate bronchoconstriction after near ambient, large-particle H2SO4 exposure in subjects with asthma. However, other investigators have found slight but significant changes in lung function following inhalation of small-particle or small-particle, low-relative-humidity (RH) H2SO4 aerosols, leading us to hypothesize that particle size and/or RH may be important variables in acid aerosol exposure. We initially studied the effects of resting inhalation of large-particle (volume median diameter, VMD, approximately equal to 6 microns) and small-particle (VMD approximately equal to 0.4 microns) aerosols with an H2SO4 concentration of 3 mg/m3 through a mouthpiece and found no effect on specific airway resistance (SRaw) or symptom scores. In a second mouthpiece study designed to compare high-RH (100%), large-particle (VMD approximately equal to 6 microns) and low-RH (less than 10%), small-particle (VMD approximately equal to 0.3 microns) aerosols with an H2SO4 concentration of 3 mg/m3, we again found no effect of either aerosol. We then examined the effects of small-particle aerosols inhaled in dry air during moderate exercise. Although breathing low-RH air during exercise provoked increases in SRaw in almost all subjects, this could not be attributed to H2SO4 since low-RH saline aerosol produced a similar result.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2008986

Aris, R; Christian, D; Sheppard, D; Balmes, J R

1991-04-01

170

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

171

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

172

Vapor-liquid equilibrium measurements for dilute nitric acid solutions  

NASA Astrophysics Data System (ADS)

Equilibrium partial pressures of H 2O and HNO 3 were measured for dilute HNO 3 solutions between 0.3 and 6.8 m at 25C. The new measurements extend the literature HNO 3 partial pressure data by two orders of magnitude down to 2 10 -8 a'tm. A critical evaluation of all data leads to a liquid-vapor equilibrium constant of 3.76 10 -7 for the HNO 3-H 2O system. This equilibrium constant, in conjunction with a complete set of activity coefficients also derived in this work, may be used to predict the equilibrium HNO 3 partial pressures at any HNO 3 concentrations. The results of a temperature study between 15 and 35C are also reported.

Tang, I. N.; Munkelwitz, H. R.; Lee, J. H.

173

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

174

Potential change during intercalation of sulfuric acid in host carbons with different textures  

Microsoft Academic Search

From the electric potential changes, the intercalation reaction of sulfuric acid in graphite was divided into two elemental processes: the charging process of the interface between graphite layer and intercalated sulfuric acid in pure stages, which corresponded to a steep increase in potential, and the stage transformation process caused by further intercalation, which showed a plateau on the potential change

Norio Iwashita; Hiroshi Shioyama; Michio Inagaki

1995-01-01

175

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...

176

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

EPA Science Inventory

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

177

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...

178

Neptunium(V) Anionic Exchange in Sulfate-Sulfuric Acid Solutions.  

National Technical Information Service (NTIS)

The purpose of this study was to investigate the anionic exchange behavior of neptunium(V) in sulfate-sulfuric acid, because neptunium is often present as a contaminant during the separation of other actinides. Sulfuric acid systems are seldom utilized in...

J. Rego J. Garrison R. Carver

1979-01-01

179

The Use of Metal Films in Studying Sulfuric Acid Droplets in the Atmosphere  

Microsoft Academic Search

The technique presented in this paper can be used to detect and measure concentration and size spectra of sulfuric acid droplets to within a very good accuracy. Light extinction measurement through reaction spots is employed to yield the size distribution of sulfuric acid droplets when sampled on a thin metal, film. By photometry through optical microscope or densitometry on electron

A. M. Hazrati

1979-01-01

180

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

EPA Science Inventory

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

181

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

182

Theoretical Studies on Gas-Phase Reactions of Sulfuric Acid Catalyzed Hydrolysis of Formaldehyde and Formaldehyde with Sulfuric Acid and H2SO4H2O Complex.  

PubMed

The gas-phase reactions of sulfuric acid catalyzed hydrolysis of formaldehyde and formaldehyde with sulfuric acid and H2SO4H2O complex are investigated employing the high-level quantum chemical calculations with M06-2X and CCSD(T) theoretical methods and the conventional transition state theory (CTST) with Eckart tunneling correction. The calculated results show that the energy barrier of hydrolysis of formaldehyde in gas phase is lowered to 6.09 kcal/mol from 38.04 kcal/mol, when the sulfuric acid is acted as a catalyst at the CCSD(T)/aug-cc-pv(T+d)z//M06-2X/6-311++G(3df,3pd) level of theory. Furthermore, the rate constant of the sulfuric acid catalyzed hydrolysis of formaldehyde combined with the concentrations of the species in the atmosphere demonstrates that the gas-phase hydrolysis of formaldehyde of sulfuric acid catalyst is feasible and could be of great importance for the sink of formaldehyde, which is in previously forbidden hydrolysis reaction. However, it is shown that the gas-phase reactions of formaldehyde with sulfuric acid and H2SO4H2O complex lead to the formation of H2C(OH)OSO3H, which is of minor importance in the atmosphere. PMID:23701044

Long, Bo; Tan, Xing-Feng; Chang, Chun-Ran; Zhao, Wei-Xiong; Long, Zheng-Wen; Ren, Da-Sen; Zhang, Wei-Jun

2013-06-01

183

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

184

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

PubMed

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

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

2013-02-01

185

[Leaching kinetics of josephinite tailings with sulfuric acid].  

PubMed

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

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

2013-07-01

186

In-situ recovery of mineral values with sulfuric acid  

SciTech Connect

In accordance with the present invention, mineral values are recovered from subsurface earth formations containing the same as well as calcium-containing materials by injecting into at least one injection well an aqueous sulfuric acid leach solution adapted to extract such mineral values from the subsurface formation and containing a solubility increasing agent, such as sodium chloride, adapted to significantly increase the solubility of calcium sulfates in water, in an amount sufficient to thus increase the solubility of calcium sulfates in water, contacting the subsurface earth formation with the leach solution for a time sufficient to extract significant amounts of mineral values from the formation and produce a pregnant leach solution containing the thus extracted mineral values and to thus solubilized significant amounts of calcium sulfates and withdrawing the pregnant leach solution from at least one producing well.

Warzel, F.M.

1985-10-15

187

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

188

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, Clia; Clark, Andrew C; Scollary, Geoffrey R

2011-11-15

189

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

190

Ecology ofSulfur-Oxidizing Bacteria inHot AcidSoils  

Microsoft Academic Search

Hotacidsoils inYellowstone National Parkarerich inelemental sulfur and harbor extensive populations ofsulfur-oxidizing bacteria. Thiobacillus thiooxi- dansisfound attemperatures below 55C,andattemperatures from55to85C Sulfolobus acidocaldarius ispresent. Thedistribution ofthese bacteria as a function oftemperature was measured bya most-probable-number dilution method, andtheir activity insitu was assessed byuseofa new technique per- mitting measurement of\\

CARL B. FLIERMANS; ANDTHOMAS D. BROCK

1972-01-01

191

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

NASA Astrophysics Data System (ADS)

Sulfuric acid aerosols are present throughout the lower stratosphere and play an important role in both polar and global ozone depletion. In the polar regions, stratospheric sulfate aerosols (SSAs) act as nuclei for the growth of polar stratospheric clouds (PSCs). Heterogeneous reactions can occur on these PSCs, leading to chlorine activation and catalytic ozone destruction. This thesis addresses the issue of polar ozone depletion through laboratory studies which examine the nucleation of PSCs on sulfuric acid. In addition, chemistry which occurs directly on sulfate aerosols may impact ozone at midlatitudes, and studies describing one such reaction are presented as well. To study the growth of type I PSCs on sulfuric acid, thin H2SO4 films were exposed to water and nitric acid vapors at stratospheric temperatures. Fourier transform infrared spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films which condensed. Supercooled liquid sulfuric acid films showed uptake of HNO3 to form ternary solutions, followed by crystallization of nitric acid trihydrate (NAT). When crystalline sulfuric acid tetrahydrate (SAT) films were exposed to nitric acid and water, condensation of a supercooled HNO3/H2O layer was often observed. As predicted by theory, some of the SAT crystal then dissolved, creating a ternary H2SO4/HNO3/H2O solution. From this solution, NAT nearly always crystallized, halting the phase change of sulfuric acid. If a supercooled nitric acid layer did not condense on frozen sulfuric acid, crystalline NAT was not deposited from the gas phase when SNAT/leq41. At significantly higher supersaturations, NAT could be forced to condense on sulfuric acid, regardless of its phase. Calculations of the contact parameter from experimental data indicate that m<0.79 for NAT on SAT, predicting a significant barrier to nucleation of NAT from the gas phase. While PSCs can form only in the cold polar regions of the stratosphere, sulfuric acid aerosols can themselves provide surfaces for heterogeneous reactions on a global scale. Studies described here show that formaldehyde is taken up readily and indefinitely by sulfuric acid, and infrared spectra of the condensed phase suggest that polymerization of formaldehyde occurs in acidic solution, even at temperatures as low as 197 K. Reaction of formaldehyde with nitric acid in sulfuric acid has also been observed, converting HNO3 to oxidized species and formaldehyde to formic acid. This reaction may have considerable impact on the atmospheric HNO3/NOx ratio, as its rate is likely comparable to the HNO3 photolysis rate.

Iraci, Laura Tracy

192

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

193

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

Microsoft Academic Search

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

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

1979-01-01

194

Sulfuric acid in the phaeophyte alga Desmarestia munda deters feeding by the sea urchin Strongylocentrotus droebachiensis  

Microsoft Academic Search

The phaeophyte alga Desmarestia munda (Order Desmarestiales) concentrates sulfuric acid (H2SO4) in cell vacuoles. The primary function of the accumulated acid in the alga's life history is unknown. To investigate if sulfuric acid works as a chemical defense, grazing by the sea urchin herbivore Strongylocentrotus droebachiensis on D. munda was compared to grazing on four common non-acidic phaeophyte algae (Alaria

K. Pelletreau; G. Muller-Parker

2002-01-01

195

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

Microsoft Academic Search

Wood samples from second generation Populus cross were shown to have different lignin contents and S\\/G ratios (S: syringyl-like lignin structures; G: guaiacyl-like lignin\\u000a structures). The lignin contents varied from 22.7% to 25.8% and the S\\/G ratio from 1.8 to 2.3. Selected samples spanning these\\u000a ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions were

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

2006-01-01

196

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

Microsoft Academic Search

Wood samples from a second generation Populus cross were shown to have different lignin contents and S\\/G ratios (S: syringyl-like lignin structures; G: guaiacyl-like lignin\\u000a structures). The lignin contents varied from 22.7% to 25.8% and the S\\/G ratio from 1.8 to 2.3. Selected samples spanning these\\u000a ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions

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

197

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

Microsoft Academic Search

A gas chromatograph\\/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and

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

1993-01-01

198

Binary nucleation of sulfuric acid-water: Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

We have developed a classical mechanical model for the H2SO4/H2O binary system. Monte Carlo simulation was performed in a mixed ensemble, in which the number of sulfuric acid molecules is fixed while that of water molecules is allowed to fluctuate. Simulation in this ensemble is computationally efficient compared to conventional canonical simulation, both in sampling very different configurations of clusters relevant in nucleation and in evaluating the free energy of cluster formation. The simulation yields molecular level information, such as the shape of the clusters and the dissociation behavior of the acid molecule in the cluster. Our results indicate that the clusters are highly nonspherical as a result of the anisotropic intermolecular interactions and that a cluster with a given number of acid molecules has several very different conformations, which are close in free energy and hence equally relevant in nucleation. The dissociation behavior of H2SO4 in a cluster differs markedly from that in bulk solution and depends sensitively on the assumed value of the free energy fhb of the dissociation reaction H2SO4+H2O-->HSO4-.H3O+. In a small cluster, no dissociation is observed. As the cluster size becomes larger, the probability of having an HSO4-.H3O+ ion pair increases. However, in clusters relevant in nucleation, the resulting ion pairs remain in contact; about 240 water molecules are required to observe behavior that resembles that in bulk solution. If a larger value of fhb is assumed to reflect its uncertainty, the probability of dissociation becomes negligible. A reversible work surface obtained for a condition typical of vapor to liquid nucleation suggests that the rate-limiting step of new particle formation is a binary collision of two hydrated sulfuric acid molecules. The ion pairs formed by dissociation play a key role in stabilizing the resulting cluster. The reversible work surface is sensitive to the assumed value of fhb, thus pointing to the need for an accurate estimate of the quantity either by ab initio calculations or experiments.

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

1998-04-01

199

Alkylation and distillation: reaction conditions, sulfuric acid usage, experiences in distillation, difficulties with excessive content of propane and sulfur  

Microsoft Academic Search

This report discussed results of experiments on several topics of operational detail of the alkylation process. One problem which had arisen in industrial-scale production was that the dehydrogenation step produced small amounts of butadiene among the normal butylene. the presence of these small amounts caused a great increase (more than a doubling) in the amount of usage of sulfuric acid

Straetz

2008-01-01

200

Dilute oxalic acid pretreatment for biorefining giant reed (Arundo ...  

Treesearch

The effects of temperature (170-190 C), acid loading (2-10% w/w) and ... Two different yeast strains, Scheffersomyces (Pichia) stipitis CBS 6054, which is a ... S . carlsbergensis attained a maximum ethanol concentration of 15.9 g/l after 48 h at...

201

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

Microsoft Academic Search

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

Yasuyuki Matsushita; Seiichi Yasuda

2003-01-01

202

Aerosol Nucleation Rates of Sulfuric Acid and Water Measured Under the Lower Tropospheric Conditions  

NASA Astrophysics Data System (ADS)

Nucleation is a gas to particle conversion process in which solid or liquid aerosol particles form directly from the gas phase species and thus is an important step in the chain of reactions that lead to cloud formation. However, the nucleation mechanisms are poorly understood. There are presently large discrepancies amongst the measured nucleation rates by different laboratory studies; nucleation rates taken under the atmospheric conditions are very rare. We perform laboratory experiments of aerosol nucleation under the atmospheric conditions with a novel chemical ionization mass spectrometer (CIMS) and nano-particle differential mobility analyzer (Nano-DMA) and water condensation nuclei counter (WCPC). Our CIMS measures low concentrations of sulfuric acid (down to 1e-6 cm-3). Measurements of Nano-DMA and WCPC provide aerosol nucleation rates. An atmospheric pressure flow reactor is used to photochemically produce sulfuric acid particles from the reactions of OH and sulfur dioxide. Sulfur dioxide is also detected by CIMS. OH forms from the photo-dissociation of water vapor using a mercury lamp and the OH concentrations are calculated based on the known photochemical reaction rates and measured photon fluxes. This OH generation method also allows for sulfuric acid calibration. We will present nucleation rates of sulfuric acid and water as a function of sulfuric acid concentration, RH and temperature under the conditions of lower troposphere. We also compare these results with those by Berndt et al. (2005) that show relatively high concentrations of sulfuric acid and water nucleation rates comparable to the atmospheric observations.

Young, L.; Benson, D. R.; Quinn, K.; Lee, S.

2006-12-01

203

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

NASA Astrophysics Data System (ADS)

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

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

2006-08-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

205

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

SciTech Connect

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

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

2008-04-01

206

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

207

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

PubMed Central

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

2011-01-01

208

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

209

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

210

Simultaneous analysis of folic acid and pantothenic acid in foods enriched with vitamins by stable isotope dilution assays  

Microsoft Academic Search

Folic and pantothenic acid were quantified in multivitamin products by stable isotope dilution assays using [2H4]folic acid and [13C3,15N]pantothenic acid as the internal standards. Detection was achieved by liquid chromatography\\/mass spectrometry which enabled unequivocal determination of the vitamins. Due to the very simple extraction procedure, analysis of the vitamins was completed within 2h. When analyzing multivitamin sweets, the intra-assay and

Michael Rychlik

2003-01-01

211

Surface Characterization of Vulcanized Rubber Treated with Sulfuric Acid and its Adhesion to Polyurethane Adhesive  

Microsoft Academic Search

Modifications produced on a vulcanized styrene butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered.The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulfonic acid moieties and C?O bonds, and the removal

Carmen M. Cepeda-Jimnez; M. Mercedes Pastor-blas; Teresa P. Ferrndiz-Gmez; Jos Miguel Martn-Martnez

2000-01-01

212

Sulfuric-acid-regeneration waste-disposal technology. Final report, June 1985November 1986  

Microsoft Academic Search

All U.S. Army Ammunition Plants (AAPs) having sulfuric acid regeneration (SAR) facilities use lime precipitation as the principal means of acid-wastewater neutralization. This is as an advanced system as is used in industrial practice. However, lime precipitation could not meet zero discharge of pollutants should these be promulgated for the sulfuric-acid industry. In fact it discharges a water high in

A. A. Balasco; D. E. Johnson; J. J. Stahr; J. I. Stevens; M. A. Fields

1986-01-01

213

Sulfur emissions  

Microsoft Academic Search

The Environmental Defense Fund challenges a recent conclusion of the Advisory Committee on Oceans and International Environmental and Scientific Affairs ''that nitrogen oxides were the limiting factor in the formation of acids, including sulfuric acid, in acid rain.'' Acceptance of this would mean shifting strategies to reduce acidic sulfur deposition by reducing regional sulfur dioxide SO emissions in eastern North

1985-01-01

214

Economic Comparison of Hydrogen Production Using Sulfuric Acid Electrolysis and Sulfur Cycle Water Decomposition. Final Report.  

National Technical Information Service (NTIS)

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 ...

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

1978-01-01

215

Reaction of ClONO with HCl on NAT, NAD, and frozen sulfuric acid and hydrolysis of NO and ClONO on frozen sulfuric acid  

Microsoft Academic Search

The reaction of ClONO with HCl on the nitric acid trihydrate (NAT) and dihydrate (NAD) and on frozen sulfuric acid solutions was studied as functions of reactant concentration and temperature representative of the stratosphere. A flow tube reactor equipped with a chemical ionization mass spectrometer detector was used. The measured reactive uptake coefficient shows a strong dependence on temperature at

D. R. Hanson; A. R. Ravishankara

1993-01-01

216

Sulfuric acid aerosol exposure in humans assessed by bronchoalveolar lavage  

SciTech Connect

Epidemiologic and experimental evidence suggests that exposure to acidic aerosols may affect human health. Brief exposures to acidic aerosols alter mucociliary clearance and increase airway responsiveness, but effects on host defense mechanisms at the alveolar level have not been studied in humans. Twelve healthy, nonsmoking volunteers between 20 and 39 yr of age were exposed for 2 h to aerosols of approximately 1,000 micrograms/m3 sulfuric acid (H2SO4) or sodium chloride (NaCl (control)), with intermittent exercise, in a randomized, double-blind fashion. Each subject received both exposures, separated by at least 2 wk. Bronchoalveolar lavage (BAL) was performed 18 h after exposure in order to detect evidence of an inflammatory response, changes in alveolar cell subpopulations, or changes in alveolar macrophage (AM) function, which is important in host defense. When compared with NaCl, exposure to H2SO4 did not increase polymorphonuclear leukocytes in BAL fluid. The percentage of T lymphocytes decreased in association with H2SO4 exposure, but the difference was not statistically significant (14.9% after NaCl, 11.5% after H2SO4; p = 0.14). Antibody-mediated cytotoxicity of AM increased in association with H2SO4 exposure (percent lysis 19.1 after NaCl, 23.6 after H2SO4; p = 0.16). No significant change was seen in release of superoxide anion or inactivation of influenza virus in vitro. Brief exposures to H2SO4 aerosol at 1,000 micrograms/m3 do not cause an influx of inflammatory cells into the alveolar space, and no evidence was found for alteration in antimicrobial defense 18 h after exposure.

Frampton, M.W.; Voter, K.Z.; Morrow, P.E.; Roberts, N.J. Jr.; Culp, D.J.; Cox, C.; Utell, M.J. (Department of Medicine, University of Rochester School of Medicine and Dentistry, NY (United States))

1992-09-01

217

A study of dilute aqueous solutions of humic acids by scanning microcalorimetry  

Microsoft Academic Search

It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting\\u000a consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged,\\u000a probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of dilute aqueous solutions\\u000a of humic acids at

A. N. Danilenko; E. E. Braudo; N. E. Pavlovskaya; E. I. Yushkova; I. L. Zhuravleva

2011-01-01

218

Dilute hydrochloric acid extraction of plant material for routine cation analysis  

Microsoft Academic Search

A hazard?free method of extracting cations from dried plant material using dilute (0.5M) hydrochloric acid has been developed for routine determination of cations in dried plant samples. Previous work has shown that hydrochloric acid can be used to quantitatively extract cations but the methods are slow and tedious. To develop a faster and less tedious method it was first necessary

J. Hunt

1982-01-01

219

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

220

Determination of Reduced Inorganic Sulfur Forms as Sulfide by Zinc-Hydrochloric Acid Distillation  

Microsoft Academic Search

A simple, rapid method for the estimation of reduced inorganic sulfur in reduced environments such as lake sediments was developed. The method involves distillation in the presence of granular zinc and hydrochloric acid and determination of sulfide as the methylene blue complex. The method gives quantitative recovery of elemental sulfur, sulfide and thiosulfate, and partial recovery of other reduced forms

R. B. Aspiras; D. R. Keeney; G. Chesters

1972-01-01

221

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

222

Candidate reference method: Determination of valproic acid in serum by isotope-dilution mass spectrometry  

Microsoft Academic Search

SummaryA method has been developed for the determination of valproic acid, without derivatization, in human serum by isotope-dilution\\u000a mass spectrometry using labelled 2-propyl[3,3,3-d3] valeric[5,5,5-d3] acid as internal standard for accurate quantification of the concentration of valproic acid in the sample. After acidification,\\u000a the analyte and internal standard are extracted withn-hexane. The amounts of valproic acid in the serum are calculated

F. Susanto; H. Reinauer

1995-01-01

223

Candidate reference method: Determination of valproic acid in serum by isotope-dilution mass spectrometry  

Microsoft Academic Search

SummaryA method has been developed for the determination of valproic acid, without derivatization, in human serum by isotope-dilution\\u000a mass spectrometry using labelled 2-propyl[3,3,3-d3]valeric[5,5,5-d3] acid as internal standard for accurate quantification of the concentration of valproic acid in the sample. After acidification,\\u000a the analyte and internal standard are extracted withn-hexane. The amounts of valproic acid in the serum are calculated from

F. Susanto; H. Reinauer

1995-01-01

224

Effects of ageing on the content in sulfur-containing amino acids in rat brain  

Microsoft Academic Search

Summary Concentrations of the sulfur-containing amino acids methionine, homocysteic acid, cysteic acid and taurine were measured in brain structures of young and old Wistar rats in an attempt to etablish a possible link between the increase in oxidative stress with ageing and changes in tissue levels of these amino acids. Contrary to data reported by others, in all brain structures

M. Strolin Benedetti; A. Russo; P. Marrari; P. Dostert

1991-01-01

225

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

Microsoft Academic Search

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

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

2001-01-01

226

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

227

Sulfuric Acid Mist Generation in Utility Boiler Flue Gas  

Microsoft Academic Search

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

Boris Altshuler

228

Temperature and intensity of sonoluminescence radiation in sulfuric acid.  

PubMed

The spectral radiation of sonoluminescence (SL) from sulfuric acid doped with various Xe concentrations has been studied in a hydrochemical simulation, including radiation effects of both continuum and line emissions. The simulation considers the same temperature for both continuum and line parts of the SL spectrum and gives results in agreement with the experiment. Also, it can properly show period-doubling dynamics for a 50 torr bubble. For most of the allowable driving pressures, it is shown that both the temperature and the intensity of SL for a 4 torr bubble are greater than those of a 50 torr bubble. However, for the range of pressures near the maximum driving conditions of the 50 torr bubble, the SL intensity of this bubble can be up to three orders of magnitude greater than the 4 torr bubble. This case, which is in agreement with the experiment, is obtained when the light-emitting region of the 50 torr bubble is about three orders of magnitude greater than the 4 torr bubble. PMID:23005534

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

2012-07-17

229

Effects of submicronic sulfuric acid aerosol on human pulmonary function  

SciTech Connect

The effects of a 4-hr exposure in an environmental chamber to an average 108 ..mu..g/m/sup 3/ sulfuric acid (H/sub 2/SO/sub 4/ (MMAD, 0.5 ..mu..g)) on pulmonary function were examined in healthy young men. Subjects were randomly assigned to either experimental (N = 18) or control (N = 17) groups. All subjects were exposed to clean air on the first day. On the second day, experimental subjects were exposed to H/sub 2/SO/sub 4/ while control subjects were re-exposed to air. Subjects exercised for 15 min at 1.5 and 3.5 hr of exposure at an intensity equivalent to 75% of predicted maximal heart rate. Ventilation was monitored during the initial 14 min of each exposure. Pulmonary function was assessed prior to, and at 2 hr and 4 hr of each exposure. Exposure to H/sub 2/SO/sub 4/ had no significant effect on minute ventilation, respiratory frequency, or tidal volume, nor did it affect pulmonary function as assessed by measures of airway resistance, specific airway conductance, forced vital capacity (FVC), forced expiratory flow in 1 sec (FEV/sub 1.0/), FEV/sub 1.0//FVC, mean expiratory flow rate between 25% and 75% FVC, and expiratory flow rate at 50% and 25% FVC. It was concluded that no changes in pulmonary function resulted from exposure to H/sub 2/SO/sub 4/ under the above conditions.

Horstman, D.; Hazucha, M.; Haak, E.; Stacy, R.

1982-05-01

230

Dilute acid hydrolysis of wheat straw hemicellulose at moderate temperature: a simplified kinetic model  

SciTech Connect

Wheat straw has been hydrolized with sulfuric acid at 34 and 90 degrees C. The treatment at 90 degrees C yields complete solubilization of hemicellulose to xylose and arabinose without significant amounts of furfural. The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism. This model is useful to explain the different behavior of the concentration of the two main sugars produced. The enhanced cellulose accessibility to enzymatic attack is also reported. 26 references.

Gonzalez, G.; Lopez-Santin, J.; Caminal, G.; Sola, C.

1986-02-01

231

Role of Cystathionine Lyase in Catabolism of Amino Acids to Sulfur Volatiles by Genetic Variants of Lactobacillus helveticus CNRZ 32  

Microsoft Academic Search

Catabolism of sulfur-containing amino acids plays an important role in the development of cheese flavor. During ripening, cystathionine -lyase (CBL) is believed to contribute to the formation of volatile sulfur compounds (VSCs) such as methanethiol and dimethyl disulfide. However, the role of CBL in the generation of VSCs from the catabolism of specific sulfur-containing amino acids is not well characterized.

Won-Jae Lee; Dattatreya S. Banavara; Joanne E. Hughes; Jason K. Christiansen; James L. Steele; Jeffery R. Broadbent; Scott A. Rankin

2007-01-01

232

Molecular Beam Studies of Reactions Between Stratospheric Gases and Supercooled Sulfuric Acid.  

National Technical Information Service (NTIS)

Sulfuric acid aerosols in the stratosphere contribute to the destruction of the ozone layer by converting inactive gases like HCl and HBr into molecules that fall apart into chlorine and bromine atoms, which catalytically destroy ozone. The first step in ...

G. M. Nathanson J. R. Morris P. M. Behr J. Splan S. Glass

2002-01-01

233

Furfural Yield and Decomposition in Sodium 2,4-Dimethylbenzinesulfonate- Sulfuric Acid-Water Solutions.  

National Technical Information Service (NTIS)

Batch-type microreactors (about 1/40 milliliter of reactants) were used to measure furfural yields from acidified xylose solutions containing sodium xylenesulfonate. Initial xylose concentration was 0.666 molar. Two levels of sulfuric acid catalyst were u...

J. M. Smuk L. L. Zoch

1965-01-01

234

Anodic Polarization Behavior of Cobalt-Chromium Alloys in Sulfuric Acid Solutions.  

National Technical Information Service (NTIS)

The anodic polarization behavior of annealed cobalt-chromium alloys in hydrogen saturated sulfuric acid solutions was investigated by using a potentiostatic technique. Polarization curves were obtained for eleven specimens, ranging from 100% cobalt to 100...

G. T. Seamon

1966-01-01

235

Molecular Beam Studies of Reactions between Stratospheric Gases and Supercooled Sulfuric Acid.  

National Technical Information Service (NTIS)

Sulfuric acid aerosols in the stratosphere contribute to the destruction of the ozone layer by converting inactive gases like HCl and HBr into molecules that fall apart into chlorine and bromine atoms, which catalytically destroy ozone. The first step in ...

G. M. Nathanson J. R. Morris P. M. Behr M. D. Antman J. Splan

2000-01-01

236

Changes in the Levels of Major Sulfur Metabolites and Free Amino Acids in Pea Cotyledons Recovering from Sulfur Deficiency  

PubMed Central

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 ?-aminobutyrate and alanine, respectively. These effects are attributed to wounding resulting from excision of the seed. 35S-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, Peter K.; Randall, Peter J.

1987-01-01

237

The solubility of ozone in aqueous solutions of sulfuric, phosphoric, and perchloric acids  

Microsoft Academic Search

The solubility of ozone in pure water and aqueous solutions of sulfuric, phosphoric, and perchloric acids was determined at\\u000a 20C. An increase in the concentration of H3PO4 and HClO4 (to 14.8 and 9.5 M, respectively) caused a monotonic decrease in the solubility of ozone. The solubility of ozone in sulfuric\\u000a acid was minimum at a 12 M concentration; the solubility

A. V. Levanov; I. V. Kuskov; E. E. Antipenko; V. V. Lunin

2008-01-01

238

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

239

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

Microsoft Academic Search

Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350C and sulfuric acid loadings from 0.92 to 7.10wt.%. An optimal LGO yield of 7.58wt.% was obtained at 270C with a

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

240

Solubilities and diffusion of trace gases in cold sulfuric acid films  

Microsoft Academic Search

The well-known technique of gas chromatography was used to determine solubilities and liquid-phase diffusion coefficients of trace gases in a thin sulfuric acid film deposited in a fused silica column. Solubilities of SO2, NO2, and N2O4 and the diffusion coefficient of SO2 were measured in the temperature range 203243K using sulfuric acid concentrations in the range of 3983wt%. The results

Stefan Langenberg; Volker Proksch; Ulrich Schurath

1998-01-01

241

The role of molecular sulfuric acid hydrates in the nucleation and reactivity of atmospheric aerosol  

Microsoft Academic Search

We have recently identified a number of new molecular sulfuric acid hydrates in condensed products from the heterogeneous SO_3\\/H_2O reaction, including a 1:1 H_2SO_4:H_2O complex and a hydrated H_2SO_4:H_2O polymer. These species show characteristic IR absorption spectra and their identification is supported by a number of computational studies. Measurements on thin films of ionic sulfuric acid hydrates reveal that these

S. Couling; A. Horn

2003-01-01

242

Experimental Insights into the Sulfuric Acid\\/Water Phase Diagram: Implications for Polar Stratospheric Clouds  

Microsoft Academic Search

We have investigated the H2SO4\\/H2O binary liquid\\/solid phase diagram using a highly sensitive differential scanning calorimeter (DSC) and infrared spectroscopy of thin films. In particular we have sought to investigate the region from pure ice to sulfuric acid hemihexahydrate (SAH, H2SO46.5H2O), including a detailed look at the sulfuric acid octahydrate (SAO). Our studies have found that there is a unique,

K. D. Beyer; A. R. Hansen

2002-01-01

243

Radio-wave attenuation and sulfuric-acid vapor content in the Venus atmosphere  

Microsoft Academic Search

Radio-wave absorption in the Venus atmosphere is investigated using radio probing data on variations of the field strengths of 5-cm and 32-cm signals. It is shown that the most probable cause of cm-wave attenuation at altitudes below 50 km is absorption by sulfuric-acid vapor. Sulfuric-acid vapor contents equal to 15 ppm at 48 km and 19 ppm at 47 km

V. N. Gubenko; O. I. Iakovlev; S. S. Matiugov; A. I. Kucheriavenkov; I. R. Vaganov

1989-01-01

244

Review and evaluation of recent literature relevant to occupational exposure - sulfuric acid  

Microsoft Academic Search

New information on the effects of sulfuric acid is reviewed in an updated supplement to the 1974 NIOSH criteria document accompanying the recommended exposure standard. In 1974, a permissible exposure limit of 1 milligram (mg) sulfuric-acid mist per cubic meter (m³) of air as a time-weighted average was recommended. Issues arising since that time include the use of catalytic converters

I. F. Sevin; L. S. Soucek

1981-01-01

245

Weak boundary layers on vulcanized styrenebutadiene rubber treated with sulfuric acid  

Microsoft Academic Search

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

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

2001-01-01

246

The removal of pyritic sulfur from A?kale lignite in aqueous suspension by nitric acid  

Microsoft Academic Search

The removal of pyritic sulfur from a Turkish lignite in aqueous suspension by nitric acid was investigated. The effects of particle size (?60, ?100 and ?200 mesh), reaction time (010800 s), nitric acid concentration (530 wt.%), temperature (25103 C) and speed of stirring (0.7520 s?1) were studied. The pyritic sulfur was quantitatively removed at boiling temperature (?103 C in Erzurum)

Semra Karaca; Muammer Akyrek; Samih Bayrakeken

2003-01-01

247

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

NASA Astrophysics Data System (ADS)

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 increased with increased sulfuric acid concentration between the range of 70 wt% (gamma initial ~ 10-4) and 90 wt% (gamma initial ~ 10- 3). To determine reaction products, a bulk study was performed. Isoprene uptake was performed at higher pressures on 1 - 2 mL 85 wt % sulfuric acid and condensed phase products were extracted and analyzed using gas chromatography/mass spectrometry (GC/MS). Isoprene was observed to polymerize in the sulfuric acid and form monoterpenes and cyclic sesquiterpenes. Finally, addition of water to the 85% sulfuric acid/isoprene product mixture released these terpenes from the condensed phase into the gas phase. Atmospheric implications for heterogeneous acid catalyzed production of mono- and sequitepenes from isoprene will be discussed.

Connelly, B. M.; Tolbert, M.

2008-12-01

248

Increase in the stratospheric background sulfuric acid aerosol mass in the past 10 years  

SciTech Connect

Data obtained from measurements of the stratospheric aerosol at Laramie, Wyoming (41{degree}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 sulfur sources, in particular, carbonyl sulfide, which is thought to be the dominant nonvolcanic source of stratospheric sulfuric acid vapor. An increase in stratospheric sulfate levels has important climatic implications as well as heterogeneous chemical effects that may alter the concentration of stratospheric ozone.

Hofmann, D.J. (Univ. of Wyoming, Laramie (USA))

1990-05-25

249

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

National Technical Information Service (NTIS)

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

S. Sopok

1988-01-01

250

Environmental Appraisal-Particulate Matter, Oxides of Sulfur, and Sulfuric Acid  

Microsoft Academic Search

The role of particulate matter and oxides of sulfur in degradation of the atmospheric environment is discussed. The Federal Air Quality Criteria for these pollutants are analyzed for their conformance with the requirement of the Clean Air Act of 1967 that they reflect the latest scientific knowledge pertinent to the indication of their effects on health and welfare. Visibility reduction

John M. Pierrard

1969-01-01

251

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

Microsoft Academic Search

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

Mary O. Amdur

1969-01-01

252

Environmental appraisal-particulate matter, oxides of sulfur, and sulfuric acid  

Microsoft Academic Search

The role of particulate matter and oxides of sulfur in degradation of the atmospheric environment is discussed. The federal air quality criteria for these pollutants are analyzed for their conformance with the requirement of the Clean Air Act of 1967 that they reflect the latest scientific knowledge pertinent to the indication of their effects on health and welfare. Visibility reduction

Puerrard

1969-01-01

253

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

Microsoft Academic Search

The stratospheric aerosol layer has traditionally been thought of as being composed of pure sulfuric acid\\/water aerosols, but recent airborne measurements of single particle composition (e.g. Murphy et al. 2007) have shown that 10-20% of sampled aerosols in the lower stratosphere have significant organic content. Since there is very little water vapor in the stratosphere, these sulfuric acid\\/organic particles will

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

2009-01-01

254

Laboratory studies of the formation of polar stratospheric clouds: Nitric acid condensation on thin sulfuric acid films  

Microsoft Academic Search

Thin sulfuric acid films were exposed to 510-810-7 torr HNO3 and 2-310-4 torr H2O and cooled to temperatures near the ice frost point. Fourier transform infrared (FTIR) spectroscopy was used to probe the condensed-phase species during isothermal experiments, and gas pressures were monitored with mass spectrometry. Supercooled liquid sulfuric acid films exposed to HNO3 (6<=SNAT<=114) showed indications of HNO3 uptake

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

1995-01-01

255

Uptake of hypobromous acid (HOBr) by aqueous sulfuric acid solutions: low-temperature solubility and reaction  

NASA Astrophysics Data System (ADS)

Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45-70wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201-252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H*=104-107mol L-1atm-1. H* is inversely dependent on temperature, with ?H=-45.05.4 kJ mol-1 and ?S=-10124 J mol-1K-1 for 55-70wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into 55-70wt% H2SO4, the solubility is described by log H*=(2349280)/T-(5.271.24). At temperatures colder than ~213K, the solubility of HOBr in 45wt% H2SO4 is at least a factor of five larger than in 70wt% H2SO4, with log H*=(3665270)/T-(10.631.23). The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Upon uptake of HOBr into aqueous sulfuric acid in the presence of other brominated gases, particularly for 70wt% H2SO4 solution, our measurements demonstrate chemical reaction of HOBr followed by evolution of gaseous products including Br2O and Br2.

Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Rammer, T. A.; Golden, D. M.

2005-06-01

256

Uptake of hypobromous acid (HOBr) by aqueous sulfuric acid solutions: low-temperature solubility and reaction  

NASA Astrophysics Data System (ADS)

Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45-70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201-252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H*=104-107 mol L-1 atm-1. H* is inversely dependent on temperature, with ?H=-45.05.4 kJ mol-1 and ?S=-10124 J mol-1 K-1 for 55-70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into 55-70 wt% H2SO4, the solubility is described by log H*=(2349280)/T-(5.271.24). At temperatures colder than ~213 K, the solubility of HOBr in 45 wt% H2SO4 is at least a factor of five larger than in 70 wt% H2SO4, with log H*=(3665270)/T-(10.631.23). The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Upon uptake of HOBr into aqueous sulfuric acid in the presence of other brominated gases, particularly for 70 wt% H2SO4 solution, our measurements demonstrate chemical reaction of HOBr followed by evolution of gaseous products including Br2O and Br2.

Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Rammer, T. A.; Golden, D. M.

2005-03-01

257

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

SciTech Connect

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

Gorensek, M.; Edwards, T.

2009-06-11

258

Feedstock mixture effects on sugar monomer recovery following dilute acid pretreatment and enzymatic hydrolysis.  

PubMed

This study seeks to investigate the effects of biomass mixtures on overall sugar recovery from the combined processes of dilute acid pretreatment and enzymatic hydrolysis. Aspen, a hardwood species well suited to biochemical processing, was chosen as the model species for this study. Balsam, a high-lignin softwood species, and switchgrass, an herbaceous energy crop with high ash content, were chosen as adjuncts. A matrix of three different dilute acid pretreatment severities and three different enzyme loading levels was used to characterize interactions between pretreatment and enzymatic hydrolysis. No synergism or antagonism was observed for any of the feedstock mixtures. Maximum glucose yield was 70% of theoretical for switchgrass and maximum xylose yield was 99.7% of theoretical for aspen. Supplemental ?-glucosidase increased glucose yield from enzymatic hydrolysis by an average of 15%. Total sugar recoveries for mixtures could be predicted to within 4% by linear interpolation of the pure species results. PMID:22522019

Brodeur-Campbell, Michael; Klinger, Jordan; Shonnard, David

2012-04-04

259

Effects of crystallinity on dilute acid hydrolysis of cellulose by cellulose ball-milling study  

SciTech Connect

The dilute acid (0.05 M H2SO4) hydrolysis at 175 oC of samples comprising varying fractions of crystalline (I?) and amorphous cellulose was studied. The amorphous content, based on XRD and NMR, and the product (glucose) yield, based on HPLC, increased by as much as a factor of three upon ball milling. These results are interpreted in terms of a model involving mechanical disruption of crystallinity by breaking hydrogen bonds in I??cellulose, opening up the structure and making more ?-1,4 glycosidic bonds readily accessible to the dilute acid. However, in parallel with hydrolysis to form liquid phase products, there are reactions of amorphous cellulose that form solid degradation products.

Zhao, Haibo; Kwak, Ja Hun; Wang, Yong; Franz, James A.; White, John M.; Holladay, John E.

2006-02-01

260

Sulfuric acid on silica-gel: an inexpensive catalyst for aromatic nitration  

Microsoft Academic Search

Solid acidic catalysts made of sulfuric acid supported on silica-gel and their application to the nitration of aromatics with nitric acid and isopropyl nitrate are described. Substrates with very different levels of activation were investigated. Methods to overcome the poisoning produced by water and to tune the catalyst activity according to the reactivity of the substrate are outlined.

Juan M Riego; Zeno Sedin; JosM Zaldvar; Nunziata C Marziano; Claudio Tortato

1996-01-01

261

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

PubMed

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

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

2012-10-26

262

Ethanol production from dilute-acid softwood hydrolysate by co-culture  

Microsoft Academic Search

Dilute-acid softwood hydrolysate, with glucose and xylose as the dominant sugars was fermented to ethanol by co-cultures.\\u000a The strains used include Saccharomyces cerevisiae 2.535 (1#), Pachysolen tannophilis ATCC 2.1662 (2#), and recombinant Escherichia coli (3#) constructed in our laboratory carrying both pdc and adhB genes derived from Zymomonas mobilis. Before fermentation, the co-cultures were adapted for five batches. Observation under

Mingyu Qian; Shen Tian; Xuefeng Li; Jing Zhang; Yaping Pan; Xiushan Yang

2006-01-01

263

Mathematical simulation of anodic intercalation of graphite in dilute nitric acid  

Microsoft Academic Search

The article suggests a mathematical model for the process of anodic intercalation of the dense graphite suspension in dilute\\u000a nitric acid, where the spontaneous intercalation is absent. The model is based on the idea of electric neutrality of a graphite\\u000a particle, due to which the anion current NO3? entering the particle is precisely equal to the quantity of electrons, which

K. B. Yemelyanov; A. Ye. Bychkov; V. L. Zelenko; L. I. Heifets

2010-01-01

264

Effect of relative humidity on the detection of sulfur dioxide and sulfuric acid using a chemical ionization mass spectrometer  

NASA Astrophysics Data System (ADS)

Detection of sulfur dioxide and sulfuric acid at high relative humidity was studied using a chemical ionization mass spectrometer (CIMS). The reactant ions used in the experiments are CO3-.nH2O (n=0-5), which react with SO2 to form SO5-.nH2O (n=0-2). H2SO4 reacts with the precursor ions to form HSO4- (m/z=97 amu) and H2SO4.CO3- (m/z=158 amu). We report the first use of the latter ionization scheme to detect sulfuric acid. High RH affects the detection of SO2 and H2SO4 by forming clusters with the reactant and product ions, reducing sensitivity. Increasing the temperature breaks these clusters. For SO2 at high RH, either SO5- (m/z=112 amu) or SO5-.H2O (m/z=130 amu) can be used for SO2 detection without a decrease in sensitivity. For H2SO4 at high RH, it is preferred to detect the ion H2SO4.CO3- because the background signal at 158 amu is small, and a better sensitivity can be achieved.

Salcedo, D.; Villalta, P. W.; Varutbangkul, V.; Wormhoudt, J. C.; Miake-Lye, R. C.; Worsnop, D. R.; Ballenthin, J. O.; Thorn, W. F.; Viggiano, A. A.; Miller, T. M.; Flagan, R. C.; Seinfeld, J. H.

2004-01-01

265

One-step synthesis of novel sulfuric acid groups' functionalized carbon via hydrothermal carbonization  

Microsoft Academic Search

The novel sulfuric acid groups' functionalized carbon has been synthesized via one-step hydrothermal carbonization of polyvinyl alcohol and hydroxyethylsulfuric acid. The novel carbon exhibited high acidity and comparable activities to sulfonic acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for the environmental-friendly processes. The copolymerization method provides an efficient procedure for the synthesis of various

Xuezheng Liang; Huiquan Xiao; Yongmiao Shen; Chenze Qi

2010-01-01

266

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

SciTech Connect

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

Bandy, A.R.; Thornton, D.C.; Driedger, A.R. III [Drexel Univ., Philadelphia, PA (United States)

1993-12-01

267

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

PubMed

The feasibility of diluted nitric acid solutions for microwave-assisted decomposition of botanical samples in closed vessels was evaluated. Oxygen pressurized atmosphere was used to improve the digestion efficiency and Al, Ca, K, Fe, Mg and Na were determined in digests by inductively coupled plasma optical emission spectrometry (ICP OES). Efficiency of digestion was evaluated taking into account the residual carbon content (RCC) and residual acidity in digests. Samples were digested using nitric acid solutions (2, 3, 7, and 14 mol L(-1) HNO(3)) and the effect of gas phase composition inside the reaction vessels by purging the vessel with Ar (inert atmosphere, 1 bar), air (20% of oxygen, 1 bar) and pure O(2) (100% of oxygen, 1 bar) was evaluated. The influence of oxygen pressure was studied using pressures of 5, 10, 15 and 20 bar. It was demonstrated that a diluted nitric acid solution as low as 3 mol L(-1) was suitable for an efficient digestion of sample masses up to 500 mg of botanical samples using 5 bar of oxygen pressure. The residual acidities in final digests were lower than 45% in relation to the initial amount of acid used for digestion (equivalent to 1.3 mol L(-1) HNO(3)). The accuracy of the proposed procedure was evaluated using certified reference materials of olive leaves, apple leaves, peach leaves and pine needles. Using the optimized conditions for sample digestion, the results obtained were in agreement with certified values. The limit of quantification was improved up to a factor of 14.5 times for the analytes evaluated. In addition, the proposed procedure was in agreement with the recommendations of the green chemistry once it was possible to obtain relatively high digestion efficiency (RCC<5%) using only diluted HNO(3), which is important to minimize the generation of laboratory residues. PMID:21238716

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

2010-11-17

268

A rapid, sensitive method for the quantitation of specific metabolites of sulfur mustard in human urine using isotope-dilution gas chromatography-tandem mass spectrometry.  

PubMed

Sulfur mustard agent (HD) (2,2'-dichloroethyl sulfide), a Schedule I compound on the Chemical Weapons Convention Schedule of Chemicals, remains a public health concern because it is simple to synthesize and it is in the chemical weapon stockpiles of several countries. A sensitive, rapid, accurate, and precise method was developed to quantitate trace levels of 1,1'-sulfonylbis [2-(methylthio) ethane] (SBMTE) in human urine as a means of assessing exposure to HD. The method used immobilized liquid-liquid extraction with diatomaceous earth, followed by the analysis of the urine extract using isotope-dilution gas chromatography-tandem mass spectrometry. Relative standard deviations were less than 8.6% at 1 ng/mL and 3.6% at 20 ng/mL. The limit of detection for SBMTE was 0.038 ng/mL in 0.5 mL of urine. PMID:15239853

Young, Carrie L; Ash, Doris; Driskell, W J; Boyer, Anne E; Martinez, Rodolfo A; Silks, L A; Barr, John R

269

Solubility and reactivity of peroxyacetyl nitrate (PAN) in dilute aqueous salt solutions and in sulphuric acid  

Microsoft Academic Search

The loss rates of PAN in several dilute aqueous salt solutions (NaBr, Na2SO3, KI, NaNO2, FeCl3, and FeSO4) and in sulphuric acid were measured at 279K with a simple bubbler experiment. They are little different from that in pure water. For 5M sulphuric acid hydrolysis and solubility were determined in the temperature range of 243293K. The hydrolysis rate kh=3.210?4s?1 at

A Frenzel; S Kutsuna; K Takeuchi; T Ibusuki

2000-01-01

270

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

271

Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs diameter.

Mortazavi, Seyedeh Z.; Novinrooz, Abdul J.; Reyhani, Ali; Mirershadi, Soghra

2010-12-01

272

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

2009-08-13

273

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

Microsoft Academic Search

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

Vince M. Gabert; Nuria Canibe; Henry Jrgensen; Bjrn O. Eggum; Willem C. Sauer

1997-01-01

274

Upper tropospheric SO2 conversion into sulfuric acid aerosols and cloud condensation nuclei  

Microsoft Academic Search

We have investigated the potential of upper tropospheric cloud condensation nuclei (CCN) formation from sulfur dioxide. This process involves three steps including SO2 conversion to gaseous sulfuric acid (GSA), homogeneous bimolecular nucleation of GSA and water vapor leading to new aerosol particles, and new aerosol particle growth via mutual coagulation and GSA-H2O condensation. Our investigation includes both measurements of SO2

Ari Laaksonen; Liisa Pirjola; Markku Kulmala; Karl-Heinz Wohlfrom; Frank Arnold; Frank Raes

2000-01-01

275

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

Microsoft Academic Search

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

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

2004-01-01

276

Associations of London, England, Daily Mortality with Particulate Matter, Sulfur Dioxide, and Acidic Aerosol Pollution  

Microsoft Academic Search

During the extreme pollution episodes of 1952 and 1962 in London, England, excesses in daily mortality were clearly evident. In this study, we examined daily British Smoke, sulfur dioxide, acid aerosols, and weather variables for their short-term associations with daily mortality in the more typical (nonepisodic) winters of 19651972. Consideration of the acid aerosol data was of special interest because

Kazuhiko Ito; George D. Thurston; Carl Hayes; Morton Lippmann

1993-01-01

277

Changes in foliar elements in red spruce seedlings after exposure to sulfuric and nitric acid mist  

Microsoft Academic Search

Red spruce (Picea rubens Sarg.) seedlings were exposed repeatedly at a field site or in a greenhouse to acidic mist containing the major sulfur and nitrogen pollutants of wet deposition in the eastern U.S.: sulfate alone, nitrate alone or with ammonium ion, and a combination of these ions. Acidities and ion concentrations ranged from below the mean to above the

J. S. Jacobson; J. P. Lassoie; J. Osmeloski; K. Yamada

1989-01-01

278

Diet and cholesterolemia: V. effects of sulfur- containing amino acids and protein  

Microsoft Academic Search

SUMMARY Interrelationships among the effects of dietary protein, sulfur-containing amino acids, and choline on the serum cholesterol concentration of the rat have been studied. Hypercholester- olemia was induced by feeding rats a diet containing cholesterol, cholic acid, and saturated fat. When the diet contained choline, additional casein alleviated the hypercholesterolemia. A similar effect was obtained with a supplement of methionine

J. C. SEIDEL; NARINDAR NATH; A. E. HARPER

279

Soluble sulfur species extracted from coal by chemical leaching. [MS thesis; mineral and coal-derived pyrite; 114 references  

Microsoft Academic Search

The nature of the soluble sulfur-containing reaction products from the desulfurization of pyrite was studied. The rate of oxydesulfurization of the two varieties of pyrite was studied under the leaching conditions of the Ames process. Concentrations of soluble sulfur species were determined for oxydesulfurization using leach solutions of sodium carbonate, sodium bicarbonate, distilled water, and dilute sulfuric acid and for

1982-01-01

280

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

281

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

282

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

NASA Astrophysics Data System (ADS)

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

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

283

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

PubMed

The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02-100. The limits of detection and determination were 0.2 and 0.6 ?g/L, respectively. The mean recovery of the stable isotope dilution assay was 102 3 % in the range between 1.0 and 100 ?g/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3-17.3 ?g/L or 2.3-10.3 ng/mg(-1) creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 ?g tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54-81 % after 6 h, depending on matrix and volunteer. After 24 h, 87-93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely. PMID:23397093

Asam, Stefan; Habler, Katharina; Rychlik, Michael

2013-02-09

284

40 CFR Appendix Xi to Part 268 - Metal Bearing Wastes Prohibited From Dilution in a Combustion Unit According to 40 CFR 268.3(c)  

Code of Federal Regulations, 2010 CFR

...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...sulfuric acid anodizing of aluminum; (2) tin plating...

2010-07-01

285

40 CFR Appendix Xi to Part 268 - Metal Bearing Wastes Prohibited From Dilution in a Combustion Unit According to 40 CFR 268.3(c)  

Code of Federal Regulations, 2010 CFR

...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...Prohibited From Dilution in a Combustion Unit According to 40 CFR 268...sulfuric acid anodizing of aluminum; (2) tin plating...

2009-07-01

286

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-Khler 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.; Sipil, M.; Barmet, P.; Curtius, J.; Dommen, J.; Ehn, M.; Ehrhart, S.; Kulmala, M.; Krten, A.; Mikkil, J.; Paasonen, P.; Petj, T.; Weingartner, E.; Baltensperger, U.

2012-10-01

287

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-Khler 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.; Sipil, M.; Barmet, P.; Curtius, J.; Dommen, J.; Ehn, M.; Ehrhart, S.; Kulmala, M.; Krten, A.; Mikkil, J.; Petj, T.; Weingartner, E.; Baltensperger, U.

2012-05-01

288

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

PubMed

Heating of batch tubular reactors with fluidized sand baths and with microwaves resulted in distinctive sugar yield profiles from pretreatment and subsequent enzymatic hydrolysis of corn stover at the same time, temperature, and dilute sulfuric acid concentration combinations and hydrothermal pretreatment conditions. Microwave heated pretreatment led to faster xylan, lignin, and acetyl removal as well as earlier xylan degradation than sand baths, but maximum sugar recoveries were similar. Solid state CP/MAS NMR revealed that microwave heating was more effective in altering cellulose structural features especially in breakdown of amorphous regions of corn stover than sand bath heating. Enzymatic hydrolysis of pretreated corn stover was improved by microwave heating compared to sand bath heating. Mechanisms were proposed to explain the differences in results for the two systems and provide new insights into pretreatment that can help advance this technology. PMID:21463933

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

2011-03-14

289

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

SciTech Connect

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

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

2004-09-01

290

Combined Effect of Ozone and Sulfuric Acid on Pulmonary Function in Man  

Microsoft Academic Search

A potential effect of the combination of ozone and sulfuric acid mist (H2SO4) on respiratory function has been postulated for humans simultaneously exposed to these two pollutants. Nine young men were exposed to 0.25?ppm ozone (O3), 12001600?g\\/m sulfuric acid aerosol (H2SO4), and a combination of O3 and H2SO4. During the 2-hr exposures, the subjects exercised (ventilation=30?L\\/min) three times for 20?min

STEVEN M. HORVATH; LAWRENCE J. FOLINSBEE; JOHN F. BEDI

1987-01-01

291

Molecular dynamics study of water transfer at supercooled sulfuric acid solution surface covered with butanol.  

PubMed

The evaporation and condensation mechanisms of water through a butanol film on sulfuric acid solution are elucidated by molecular dynamics simulation. A previous experiment by Nathanson et al. reported the mass accommodation coefficient ? to be almost unity, whereas MD simulation of water scattering on the butanol film on water predicted a value of ? significantly smaller than unity. This discrepancy is elucidated by considering the protonated butanol at the sulfuric acid solution surface, which roughens the surface layer, and the low temperature at the supercooled condition. PMID:23659358

Sakaguchi, Suguru; Morita, Akihiro

2013-05-22

292

Addition of sulfur chlorides to RCH = CCl 2 in neutral and acid media  

Microsoft Academic Search

Summary 1.In presence of anhydrous ferric chloride S2Cl2 adds readily to RCH = CCl2 with formation of. The addition of SCl2 gives the same disulfides, and simultaneous chlorination of the CCl2=CH group occurs.2.Addition on S2Cl2 to RHC=CCl2 in a medium of sulfuric acid proceeds as a conjugated reaction and results in the formation of a,a'-dithio dicarboxylic acids.3.When heated, 5-chloro-2-mercaptovaleric acid

L. I. Zakharkin; V. V. Korneva

1958-01-01

293

Pretreatment of woody and herbaceous biomass for enzymatic saccharification using sulfuric acid-free ethanol cooking  

Microsoft Academic Search

A sulfuric acid-free ethanol cooking (SFEC) treatment was developed to achieve complete saccharification of the cellulosic component of eucalyptus and baggase flour, thereby avoiding the problems associated with the use of strong acid catalysts. Cutter-milled flours were exposed to an ethanol (EtOH)\\/water\\/acetic acid mixture in an autoclave. Enzymatic hydrolysis experiments of the pretreated samples demonstrated that almost complete conversion of

Yoshikuni Teramoto; Seung-Hwan Lee; Takashi Endo

2008-01-01

294

Sulfuric acid leaching of ocean manganese nodules using aromatic amines as reducing agents  

Microsoft Academic Search

Sulfuric acid leaching of ocean manganese nodules was carried out using aromatic amines as reducing agents. Seven aromatic amines were tested and they were: aniline, o-phenylene diamine, o-aminobenzoic acid, o-nitroaniline, p-amino toluene, p-aminobenzene sulfonic acid and l-naphthylamine. At ambient temperature and pressure, these aromatic amines markedly increased metal extraction from the nodules. Generally, extraction of Mn, Ni and Co increased

Yahui Zhang; Qi Liu; Chuanyao Sun

2001-01-01

295

EXTRACTION EQUILIBRIA OF SILVER WITH A SULFUR-CONTAINING CARBOXYLIC ACID  

Microsoft Academic Search

A new carboxylic acid extractant containing a sulfur atom, ?-butylthiolauric acid(abbreviated as ?-BTLA) was synthesized to investigate the extraction equilibrium of silver(I) from 1 mol\\/dm aqueous ammonium nitrate solution with its toluene solution at 30C. Moreover, the extraction of silver(I) with palmitic acid in toluene was studied to compare with the extraction properties of ?-BTLA. It was found that silver(I)

Yoshinari BABA; Katsutoshi INOUE

1984-01-01

296

Hydrates in binary sulfuric acid-water vapor: Comparison of CIMS measurements with the liquid-drop model  

Microsoft Academic Search

We report calculations of the distribution of sulfuric acid-water hydrates under atmospheric conditions using the liquid-drop hydrate model. The model-computed total acid concentrations (free acid plus hydrated acid) are compared with chemical ionization mass spectrometer (CIMS) measurements of total sulfuric acid vapor over solutions of varying concentration [Marti et al., 1997] Results from this first direct comparison with experimental measurement

Robert McGraw; Rodney J. Weber

1998-01-01

297

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

SciTech Connect

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

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

2004-08-01

298

Sulfuric acid speleogenesis of Carlsbad Cavern and its relationship to hydrocarbons, Delaware basin, New Mexico and Texas  

Microsoft Academic Search

Sulfur-isotope data and pH-dependence of the mineral endellite support the hypothesis that Carlsbad Cavern and other caves in the Guadalupe Mountains were dissolved primarily by sulfuric acid rather than by carbonic acid. Floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in ³²S; δ³⁴S values as low as -25.8 {per thousand} (CDT)

Hill

1990-01-01

299

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

2013-01-28

300

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

SciTech Connect

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

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

2009-01-01

301

Hydrogen-Bond Breaking and Proton Exchange in Collisions of Gaseous Formic Acid with Liquid Sulfuric Acid  

NASA Astrophysics Data System (ADS)

Gas-liquid scattering experiments provide direct observations of the fate of hydrogen-bonding molecules striking the surfaces of acidic liquids. Collisions of gaseous formic acid with concentrated sulfuric acid show that impinging monomers (HCOOH and DCOOD) scatter inelastically from the interface or become trapped by surface H_2SO_4. Most trapped DCOOD molecules undergo proton exchange before desorbing from the acid, indicating that gas-surface accommodation almost always leads to reaction with H_2SO_4 molecules. This proton transfer is not inhibited by dimerization of the formic acid: The dimers readily undergo intramolecular hydrogen bond cleavage and D-H exchange before desorbing from the acid.

Klassen, Jane K.; Nathanson, Gilbert M.

1996-07-01

302

Kinetics of hydrogen peroxide decomposition in aqueous sulfuric acid over palladium\\/carbon: effcet of acid concentration  

Microsoft Academic Search

Decomposition of H2O2 over Pd (5%)\\/carbon in an aqueous sulfuric acid solution at different acid concentrations (0-10 mol\\/L) and temperatures (281-313\\u000a K) in a magnetically stirred glass reactor has been investigated. The catalytic activity, activation energy and frequency\\u000a factor for the decomposition decrease with increasing acid concentration; the decrease in the activation energy is, however,\\u000a very small.

Vasant R. Choudhary; Abaji G. Gaikwad

2003-01-01

303

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

304

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

SciTech Connect

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

Galloway, T.R.

1981-05-01

305

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

NASA Astrophysics Data System (ADS)

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

Galloway, T. R.

1981-05-01

306

Seasonal and Spatial Variations in the Chemical and Sulfur Isotopic Composition of Acid Deposition in Niigata Prefecture, Japan  

Microsoft Academic Search

The following measurements were carried out to clarify acid deposition in Niigata Prefecture, an area facing to the Sea of Japan. 1) Acid deposition fluxes and sulfur isotopic ratios of atmospheric deposition were measured at 9 sites in the prefecture in 1999. 2) Atmospheric deposition was collected daily at one site in 1997, to measure the sulfur isotopic variations of

Tsuyoshi Ohizumi; Naoko Take; Noboru Moriyama; Osamu Suzuki; Minoru Kusakabe

2001-01-01

307

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

SciTech Connect

The uptake of Hci molecules by acqueous sulfuric acid droplets was measured at 283 K as a function of acid mole fraction. In the apparatus a controllable stream of monodispersed droplets is produced by a vibrating orifice jet. The droplets enter a flow system containing HCl(g). The droplets are switched on and off while the density of the species is continuously monitored by infrared absorption. From the on-off signal a coefficient for the probability of gas uptake upon collision with the liquid surface is calculated. This coefficient is 0.15 for pure water, remains constant up to 0.1 mole fraction of H{sub 2}SO{sub 4} (40 wt%) and then drops sharply to < 10{sup {minus}2} at 0.2 mole fraction (60 wt%). The results are in accord with calculations based on the decrease in the solubility of HCl with increasing H{sub 2}SO{sub 4} mole fraction. Increasing acidity reduces the dissociation of HCl into H{sup +} and Cl{sup {minus}} in solution. Results indicate that mass accommodation coefficients are large enough so that the HCl content of stratospheric aerosols will be determined entirely by this solubility.

Watson, L.R.; Van Doren, J.M.; Davidovits, P. (Boston Coll., Chestnut Hill, MA (United States)); Worsnop, D.R.; Zahniser, M.S.; Kolb, C.E. (Aerodyne Research, Inc., Billerica, MA (United States))

1990-04-20

308

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

309

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

NASA Astrophysics Data System (ADS)

The dissolution of quartz in dilute aqueous solutions of organic acids at 25 and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 ?mole/Kg compared to 50 ?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 anions 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.

1988-06-01

310

Chamber Exposures of Children to Mixed Ozone, Sulfur Dioxide, and Sulfuric Acid  

Microsoft Academic Search

To help assess acute health effects of summer air pollution in the eastern United States, we simulated ambient acid summer haze as closely as was practical in a laboratory chamber. We exposed young volunteers who were thought to be sensitive to this pollutant mixture on the basis of previous epidemiologic evidence. Specifically, we exposed 41 subjects aged 912 y to

William S. Linn; Henry Gong Jr; Deborah A. Shamoo; Karen R. Anderson; Edward L. Avol

1997-01-01

311

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

Microsoft Academic Search

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

A. Seidel; Y. Zimmels

1998-01-01

312

The influence of potential on the tribocorrosion of nickel and iron in sulfuric acid solution  

Microsoft Academic Search

Tribocorrosion tests on nickel and iron in aerated sulfuric acid at various concentrations were conducted using a new apparatus designed and built for evaluating cojoint action of corrosion and wear. It consists of a teflon cell mounted on a ball-on-disc tribometer. The rider is a ball of polycrystalline alumina sliding in a reciprocal motion on the flat specimen. The apparatus

J. Takadoum

1996-01-01

313

Study of SO sub 2 - Emission-Problem in Sulfuric Acid Equipments.  

National Technical Information Service (NTIS)

A noble metal catalyst was developed in order to reduce SO2 emission of sulfuric acid production plants. The discrepancy in SO2/SO3 conversion yield between laboratory and field testing of a noble metal catalyst was investigated, with a view to catalyst p...

H. J. Brockmeyer R. Blaha

1981-01-01

314

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...

315

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...

316

Activity and osmotic coefficients of aqueous sulfuric acid at 298.15 K  

Microsoft Academic Search

A critical evaluation of the mean activity coefficient, ?, and osmotic coefficient, ?, of aqueous sulfuric acid at 298.15 K is presented for the molality range of 0 to 28 mol?kg?1. Osmotic coefficients were calculated from direct vapor pressure measurements, from isopietic measurements or from freezing point depression measurements. Activity coefficients were calculated from electromotive force measurements of galvanic cells.

Bert R. Staples

1981-01-01

317

A new route to high yield sugars from biomass: phosphoric-sulfuric acid.  

PubMed

We have developed a simple and effective route for the high yield extraction of sugars from cellulosic based biomass. This process uses a combination of a cellulose decrystallization step with a mixture of phosphoric and sulfuric acid, followed by a hydrolysis step producing sugars (xylose and glucose) with yields of approximately 90%. PMID:19865666

Harmer, Mark A; Fan, Analine; Liauw, Ann; Kumar, Ravinash Krishna

2009-09-16

318

Furnace Injection of Alkaline Sorbents for Sulfuric Acid Removal. Final Report.  

National Technical Information Service (NTIS)

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 Labo...

G. M. Blythe

2004-01-01

319

Occurrence of Titanium, Vanadium, Chromium, and Sulfuric Acid in the Ascidian Eudistoma ritteri  

Microsoft Academic Search

The body tissues of the colonial ascidian Eudistoma ritteri are shown by quantitative spectrographic analysis to contain up to the following amounts of related metals (parts per million of dry weight): titanium, 1512; vanadium, 471; and chromium, 144. Body tissues and tunic fluid show a pH of 1.5 due to the presence of sulfuric acid.

Estees P. Levine

1961-01-01

320

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

Microsoft Academic Search

Sulfuric acid aerosols are present throughout the lower stratosphere and play an important role in both polar and global ozone depletion. In the polar regions, stratospheric sulfate aerosols (SSAs) act as nuclei for the growth of polar stratospheric clouds (PSCs). Heterogeneous reactions can occur on these PSCs, leading to chlorine activation and catalytic ozone destruction. This thesis addresses the issue

Laura Tracy Iraci

1997-01-01

321

Effect of Sulfuric Acid on Swelling Behavior of an Expansive Soil  

Microsoft Academic Search

Soil often becomes contaminated with a variety of chemicals due to leakage of under\\/aboveground chemical storage tanks, improper discharge of waste, or improper design of waste containment facilities. Contaminated soil water can influence the soil's behavior seriously. Mineralogical alterations play a vital role in such circumstances. This paper describes the impact of varying concentrations of sulfuric acid solutions on the

P. V. Sivapullaiah; B. Guru Prasad; M. M. Allam

2009-01-01

322

Anodic Polarization Behavior of Titanium and Titanium Alloys in Sulfuric Acid Solutions.  

National Technical Information Service (NTIS)

The study was made to investigate the anodic polarization behavior of commercially-available titanium alloys in sulfuric acid solutions. Six materials were investigated at 22 plus or minus 1C using the potentiostatic technique. The electrolyte was 1, 5, a...

J. M. Peters

1966-01-01

323

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

Microsoft Academic Search

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

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

2003-01-01

324

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

325

Determination of a range of concern for mobile source emissions of sulfuric acid  

Microsoft Academic Search

This paper describes an effort by the Emission Control Technology Division of the EPA to establish a range of concern for sulfuric acid (HSO) emissions from mobile sources. In light of the action called for in section 202(a)(4) of the Clean Air Act (CAA) and due to a concern within industry as to what emission levels will be used as

C. A. Harvey; R. J. Garbe

1981-01-01

326

Molecular Beam Studies of Reactions of Protic Gases with Bare and Surfactant-Coated Sulfuric Acid.  

National Technical Information Service (NTIS)

Gas-liquid scattering experiments were used to investigate the uptake of HCl and HBr, the evaporation of water, and the hydrolysis of N2O5 in sulfuric acid coated with the soluble surfactants n-butanol and n-hexanol under atmospheric conditions. The exper...

G. M. Nathanson

2007-01-01

327

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

Microsoft Academic Search

Interfacial behavior of cysteine (Cys) between mild steel and sulfuric acid solution as a corrosion inhibitor has been studied with electrochemical AC (alternating current) and DC (direct current) techniques at (25.00.1) C. The AC impedance results were evaluated using equivalent circuits in which a constant phase element (CPE) has been replaced with double layer capacitance (Cdl) to represent the frequency

Muzaffer zcan; Faruk Karada?; Ilyas Dehri

2008-01-01

328

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

329

Catalytic process for removing SO from sulfuric acid plant off gases  

Microsoft Academic Search

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

1976-01-01

330

Altered Sulfur Amino Acid Metabolism In Immune Cells of Children Diagnosed With Autism  

Microsoft Academic Search

Autism Spectrum Disorder (ASD) is a behaviorally defined neurodevelopmental disorder whose etiology is poorly understood. Recent studies have shown that autistic children may be experiencing increased inflammation and oxidative stress. Altered immune regulation may be one contributing factor to inflammation and oxidative stress in autistic children. Sulfur amino acid (SAA) metabolism plays a critical role in regulating blood leukocyte functions

Jung H. Suh; William J. Walsh; Woody R. McGinnis; Allen Lewis; Bruce N. Ames

2008-01-01

331

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

Microsoft Academic Search

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

A. Krten; L. Rondo; S. Ehrhart; J. Curtius

2010-01-01

332

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

EPA Science Inventory

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

333

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

SciTech Connect

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

Gorensek, M.; Summers, W.

2010-03-24

334

Heterogeneous chemistry of alkylamines with sulfuric acid: implications for atmospheric formation of alkylaminium sulfates.  

PubMed

The heterogeneous interaction of alkylamines with sulfuric acid has been investigated to assess the role of amines in aerosol growth through the formation of alkylaminium sulfates. The kinetic experiments were conducted in a low-pressure fast flow reactor coupled to an ion drift-chemical ionization mass spectrometer (ID-CIMS). The measurements of heterogeneous uptake of methylamine, dimethylamine, and trimethylamine were performed in the acidity range of 59-82 wt % H(2)SO(4) and between 243 and 283 K. Irreversible reactive uptakes were observed for all three alkylamines, with comparable uptake coefficients (gamma) in the range of 2.0 x 10(-2) to 4.4 x 10(-2). The measured gamma value was slightly higher in more concentrated sulfuric acid and at lower temperatures. The results imply that the heterogeneous reactions of alkylamines contribute effectively to the growth of atmospheric acidic particles and, hence, secondary organic aerosol formation. PMID:20192255

Wang, Lin; Lal, Vinita; Khalizov, Alexei F; Zhang, Renyi

2010-04-01

335

Heterogeneous interaction of formaldehyde with cold sulfuric acid: Implications for the upper troposphere and lower stratosphere  

NASA Astrophysics Data System (ADS)

Laboratory studies of formaldehyde uptake on thin sulfuric acid films indicate that HCHO can be taken up for long periods of time without saturation. Initial Henry's law solubility coefficients are large (H* = 106-107 M atm-1) at stratospheric temperatures. This uptake is due to rapid formation of HCHO(aq), CH2(OH)2, and possibly HOCH2OSO2(OH) in solution. Over a longer time period, steady-state uptake continues with ??0.002 due to formaldehyde polymerization. Although uptake by stratospheric sulfate aerosols will not provide a significant sink for atmospheric formaldehyde, it may lead to high condensed-phase concentrations of HCHO and polymerization in solution. Reaction of condensed HCHO with nitric acid in sulfuric acid has also been observed, converting HNO3 to odd nitrogen (NOx) and formaldehyde to formic acid. This reaction may have considerable impact on the HNO3/NOx ratio, as its rate is likely comparable to the HNO3 photolysis rate.

Iraci, Laura T.; Tolbert, Margaret A.

1997-07-01

336

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

SciTech Connect

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

Butler, N.L.

1984-05-21

337

Parenteral sulfur amino acid requirements in septic infants  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

338

Reflex-mediated desquamation of bronchiolar epithelium in guinea pigs exposed acutely to sulfuric acid aerosol.  

PubMed Central

Terminal conducting airways are known to be vulnerable to direct injury by a variety of noxious aerosols. Sulfuric acid aerosol, a by-product of fossil fuel combustion, produces desquamation of terminal bronchiolar epithelium in guinea pigs that is believed to result from direct deep lung irritation, an effect separable from reflex airway constriction induced by sulfuric acid. To characterize desquamation of bronchiolar epithelium, 20 guinea pigs were exposed to 32.6 mg/cu m sulfuric acid aerosol with a mass median aerodynamic diameter of 1.0 micron for 4 hours. The guinea pigs were killed upon termination of the exposure, or 24 hours later, and airway alterations were evaluated by light and transmission electron microscopy. To test whether the development of bronchiolar epithelial desquamation is independent of reflex airway constriction, 24 guinea pigs were exposed to an identical aerosol for 4 hours after pretreating half with 5 mg/kg atropine sulfate intraperitoneally to inhibit airway constriction. Sulfuric acid produced diffuse pulmonary hyperinflation with areas of consolidation and atelectasis. Epithelial desquamation occurred in airways supplying regions of developing atelectasis and was most extensive in terminal bronchioles. Parasympathetic effector blockade with atropine eliminated epithelial desquamation. These results indicate that sulfuric acid-produced desquamation of terminal bronchiolar epithelium is not separable from reflex airway constriction and that terminal conducting airways are vulnerable not only to direct injury by noxious aerosols but also to indirect, reflex-mediated injury. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14

Brownstein, D. G.

1980-01-01

339

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

Microsoft Academic Search

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

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

2010-01-01

340

Airway Reactivity to Sulfate and Sulfuric Acid Aerosols in Normal and Asthmatic Subjects  

Microsoft Academic Search

Recent epidemiologic studies have emphasized a relationship between alteration in lung function, respiratory symptoms in asthmatics, and elevated levels of sulfate air pollutants. In asthmatics, it has been reported that 1) the more acidic sulfate aerosols, sulfuric acid (H2SO4) and ammonium bisulfate (NH4HSO4), provoked the greatest changes in lung function and 2) a definite exposure-response relationship exists for H2SO4 inhalation.

Mark J. Utell; Paul E. Morrow

1984-01-01

341

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

342

HCl uptake through films of pentanoic acid and pentanoic acid/hexanol mixtures at the surface of sulfuric acid.  

PubMed

Molecular beam scattering experiments are used to investigate collisions and reactions of HCl with deuterated sulfuric acid containing 0-0.2 M pentanoic acid (PA) and mixtures of PA and hexanol. Surface tension measurements at 296 K indicate that PA segregates to the surface of the acid, reaching coverages of 58% and 52% of maximum packing on 60 and 68 wt % D(2)SO(4), respectively. We find that these films increase HCl entry into the acid at low PA surface coverage at 213 K. This enhancement is attributed to the dissociation of HCl molecules that come into contact with surface COOH groups and protonate them. At higher coverages, the PA film becomes more compact and impedes HCl uptake. Comparisons with films of pure hexanol and pentanoic acid/hexanol mixtures indicate that surface OH groups are more effective than COOH groups in catalyzing HCl entry. They also suggest that the PA films consist of patchy regions of tightly packed molecules, which are pushed away from the surface upon addition of the more surface active hexanol. HCl entry into the pure and mixed films can be analyzed quantitatively using a two-step model in which adsorbed HCl molecules penetrate between the alkyl chains and then dissociate at the surfactant-acid interface. PMID:19924886

Burden, Daniel K; Johnson, Alexis M; Nathanson, Gilbert M

2009-12-24

343

HCl Uptake through Films of Pentanoic Acid and Pentanoic Acid/Hexanol Mixtures at the Surface of Sulfuric Acid  

NASA Astrophysics Data System (ADS)

Molecular beam scattering experiments are used to investigate collisions and reactions of HCl with deuterated sulfuric acid containing 0-0.2 M pentanoic acid (PA) and mixtures of PA and hexanol. Surface tension measurements at 296 K indicate that PA segregates to the surface of the acid, reaching coverages of 58% and 52% of maximum packing on 60 and 68 wt % D2SO4, respectively. We find that these films increase HCl entry into the acid at low PA surface coverage at 213 K. This enhancement is attributed to the dissociation of HCl molecules that come into contact with surface COOH groups and protonate them. At higher coverages, the PA film becomes more compact and impedes HCl uptake. Comparisons with films of pure hexanol and pentanoic acid/hexanol mixtures indicate that surface OH groups are more effective than COOH groups in catalyzing HCl entry. They also suggest that the PA films consist of patchy regions of tightly packed molecules, which are pushed away from the surface upon addition of the more surface active hexanol. HCl entry into the pure and mixed films can be analyzed quantitatively using a two-step model in which adsorbed HCl molecules penetrate between the alkyl chains and then dissociate at the surfactant-acid interface.

Burden, Daniel K.; Johnson, Alexis M.; Nathanson, Gilbert M.

2009-11-01

344

Heterogeneous Interactions of Ethanol with Low-Temperature Aqueous Sulfuric Acid  

NASA Astrophysics Data System (ADS)

Tropospheric ethanol has both biogenic and anthropogenic sources. Evaporative emissions of ethanol will increase as its use in gasoline increases. Since ethanol has a sufficiently long lifetime to reach the upper troposphere and it is quite soluble in water, its interactions with tropospheric sulfate particles are of interest. Furthermore, ethanol undergoes two different reactions in acidic media and is therefore a useful molecule to test the ability of tropospheric sulfate to process organic matter. The reactivity ethanol exhibits in sulfuric acid is applicable to other primary alcohols, including biogenic compounds such as 2-methyl-3-buten-2-ol. The solubility of ethanol in low-temperature sulfuric acid + water solutions has been studied in a traditional Knudsen cell. Experimental conditions were representative of the upper troposphere; acid composition ranged from 40 to 80 wt. % sulfuric acid and temperature from 215 to 240 K. The solubility of ethanol increases with decreasing temperature and increasing acidity, with measured Henry's law coefficients ranging from 104 to 109 M atm-1. Experimental evidence for the heterogeneous reaction of ethanol will be discussed as well.

Staton, S. J.; Michelsen, R. R.; Iraci, L. T.

2003-12-01

345

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

SciTech Connect

We evaluated a commercially available, double-indicator-dilution densitometric system for the estimation of pulmonary extravascular water volume in oleic acid-induced pulmonary edema. Indocyanine green and heavy water were used as the nondiffusible and diffusible 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 radioisotope methods. The measured volume was not influenced by changes in cardiac index over a range of 1 to 4 L.min.m2. This system is less invasive than the thermal-dye technique and has potential for repeated clinical measurements of pulmonary extravascular lung water and cardiac output.

Leksell, L.G.; Schreiner, M.S.; Sylvestro, A.; Neufeld, G.R. (Univ. of Pennsylvania School of Medicine, Philadelphia (USA))

1990-04-01

346

Coherence in the momentum distribution of protons in dilute acids and bases  

NASA Astrophysics Data System (ADS)

The momentum distributions of the protons in dilute concentrations of HCl, NaOH and KOH have been measured at room temperature using deep inelastic neutron scattering. We find easily observable changes in the overall momentum distribution even for 5% concentrations of HCL. There is clear indication of a bimodal spatial distribution of the protons that is coherent over both sites. The number of protons involved in bimodal coherent motion appears to be much greater than the number of defects added to the water structure by introducing the acid or base. We see a barely significant difference between the Na and K signals, indicating that either the two ions have a nearly identical effect on the hydrogen bonds surrounding them or they have very little effect compared to the presence of the OH.

Reiter, George; Mayers, Jerry; Abdul-Redah, Tyno

2006-11-01

347

Furfural degradation in a dilute acidic and saline solution in the presence of glucose.  

PubMed

A kinetic study has been performed on the degradation of furfural in a dilute acidic and saline solution with and without the presence of glucose. Experiments have been performed in a stirred batch reactor. The degradation of furfural alone was accurately predicted both using a first- and a second-order kinetic model. It was shown that furfural is degrading significantly faster when glucose is present in the reaction mixture. In the series with glucose present distinct second-order reaction kinetics were observed. From experiments with varying concentrations of glucose it turned out that an additional (second-order) reaction had to be added to the reaction mechanism in order to satisfactorily predict the experimental data. This additional reaction incorporated the initial glucose concentration as a constant in the Arrhenius expression for the reaction rate constant. Furthermore, it has been argued that this second-order reaction could well be a Diels-Alder reaction. PMID:23707814

Danon, B; van der Aa, L; de Jong, W

2013-05-03

348

Structural characterization and comparison of switchgrass ball-milled lignin before and after dilute acid pretreatment.  

PubMed

To reduce the recalcitrance and enhance enzymatic activity, dilute H(2)SO(4) pretreatment was carried out on Alamo switchgrass (Panicum virgatum). Ball-milled lignin was isolated from switchgrass before and after pretreatment. Its structure was characterized by (13)C, HSQC, and (31)P NMR spectroscopy. It was confirmed that ball-milled switchgrass lignin is of HGS type with a considerable amount of p-coumarate and felurate esters of lignin. The major ball-milled lignin interunit was the beta-O-4 linkage, and a minor amount of phenylcoumarin, resinol, and spirodienone units were also present. As a result of the acid pretreatment, there was 36% decrease of beta-O-4 linkage observed. In addition to these changes, the S/G ratio decreases from 0.80 to 0.53. PMID:19701727

Samuel, Reichel; Pu, Yunqiao; Raman, Babu; Ragauskas, Arthur J

2009-08-24

349

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

2011-02-18

350

Equilibrium Analysis of Aggregation Behavior in the Solvent Extraction of Cu(II) from Sulfuric Acid by Didodecylnaphthalene Sulfonic Acid  

Microsoft Academic Search

By use of the principles of equilibrium analysis, the liquid-liquid cation exchange of Cu(II) from aqueous sulfuric acid at 25C by didodecylnaphthalenesulfonic acid (HDDNS) in toluene may be understood in terms of small hydrated aggregated species in the organic phase. Extraction data have been measured as a function of organic-phase HDDNS molarity (1.0 10 to 1.0 10), aqueous

Bruce A. Moyer; C. F. Jr. Baes; G. N. Case; G. J. Lumetta; N. M. Wilson

1993-01-01

351

Corrosion Resistance of Selected Ceramic Materials to Sulfuric Acid.  

National Technical Information Service (NTIS)

The Bureau of Mines is investigating the acid resistance of ceramic materials to identify construction materials for emerging technology in chemical and metallurgical processes. Eight commercial ceramic materials were evaluated: two red shale, two firecla...

J. P. Bennett

1986-01-01

352

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

SciTech Connect

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.

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

2011-12-01

353

Sodium sulfate solubilities in high temperature aqueous sodium chloride and sulfuric acid solutionspredictions of solubility, vapor pressure, acidity, and speciation  

Microsoft Academic Search

Experimental measurements of the solubility of sodium sulfate in aqueous solutions containing both sodium chloride and sulfuric acid in the temperature range 250 to 374C are reported. These measurements have been combined with previous data on the solubility of sodium sulfate in water, in aqueous sodium chloride, and in sulfuric acid solutions to produce a comprehensive model describing the solubility

M. H. Lietzke; William L. Marshall

1986-01-01

354

Laboratory studies of the formation of polar stratospheric clouds: Nitric acid condensation on thin sulfuric acid films  

NASA Astrophysics Data System (ADS)

Thin sulfuric acid films were exposed to 5 10-8 - 8 10-7 torr HNO3 and 2 - 3 10-4 torr H2O and cooled to temperatures near the ice frost point. Fourier transform infrared (FTIR) spectroscopy was used to probe the condensed-phase species during isothermal experiments, and gas pressures were monitored with mass spectrometry. Supercooled liquid sulfuric acid films exposed to HNO3 (6 ? SNAT ? 114) showed indications of HNO3 uptake to form ternary solutions of approximately 4 wt % HNO3, 38 wt % H2SO4, and 59 wt % H2O, followed by crystallization of nitric acid trihydrate (NAT). NAT crystallization did not initiate significant crystallization of the supercooled H2SO4, but the H2SO4 often crystallized to sulfuric acid tetrahydrate (SAT) upon warming. In contrast, when crystalline SAT films were exposed to HNO3 and water, NAT did not condense within several hours, even at HNO3 saturation ratios of 30 or higher. Calculations of the contact parameter from experimental data indicate that m <0.76 for NAT on SAT. Our film studies suggest that crystalline polar stratospheric cloud (PSC) growth is most easily accomplished when stratospheric sulfate aerosols (SSAs) remain liquid, absorb HNO3, and produce crystalline nitric acid trihydrate via heterogeneous nucleation. If SSAs crystallize to SAT at some point during the winter, nitric acid condensation is hindered, and PSC formation could become more difficult.

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

1995-10-01

355

[A study of diluted aqueous solutions of humic acids by scanning microcalorimetry].  

PubMed

It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged, probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of diluted aqueous solutions of humic acids at approximately 58 degrees C has been found by differential scanning microcalorimetry, which indicates an increase in the hydration of hydrophobic groups. A jumpwise increase in heat capacity in the temperature range from 86 to 90 degrees C was also found, which is due likely to the hydration of hydrophobic groups in the interior of "micelles", due to the "devitrification" of the hydrophobic nucleus of micelle-like structures. It was shown that increasing the duration of vermicomposting leads to an increase in the relative content of the hydrophobic fraction of humic acids and in the cooperativity of the thermodynamic transition, which manifests itself in a jump of heat capacity, which probably results from the increase in the "micelle" size. PMID:21442885

Danilenko, A N; Braudo, E E; Pavlovskaia, N E; Iushkova, E I; Zhuravleva, I L

356

Spatial Distribution of Carbon Dioxide, Hydrogen Peroxide, and Sulfuric Acid on Europa  

NASA Astrophysics Data System (ADS)

The distributions of CO2, H2O2, and hydrated H2SO4 were investigated from 80 W to 300 W longitude using infrared spectral maps from Galileo NIMS. Europa's 4.25-micrometer carbon dioxide band (Smythe et al., LPSC, 1998) is present in the equatorial region of the leading hemisphere but is absent on the trailing hemisphere. Band strength maps show a non-uniform distribution that correlates with diffuse dark regions on the leading hemisphere. Since impacts and meteoritic infall are greatest on this hemisphere, Europa's CO2 is suggested to be radiolytically produced in dark carbonaceous meteoritic deposits. Hydrogen peroxide, which is formed on Europa in the radiolysis of water ice (Carlson et al., Science 283, 2062, 1999), exhibits an absorption band at 3.5 micrometers. This absorption is present in equatorial and mid latitudes on Europa's leading hemisphere. The presence of H2O2 on the leading side and its non-detection on the trailing hemisphere may be due to the greater abundance of pure ice on the leading side compared to the trailing hemisphere. Hemispherical differences in chemical impurities and the resulting radiation chemistry pathways may also be involved. Europa's hydrated material, suggested to be sulfuric acid hydrate that is radiolytically produced from sulfur in a continuous cycle (Carlson, Johnson, and Anderson, Science 286, 97, 1999), exhibits a trailing side enhancement. The global distribution is consistent with an Iogenic sulfur ion implantation. High-resolution maps show patterns that correlate with geological features. Sublimation of water during diapiric heating can enhance sulfur and sulfuric acid concentrations and produce such correlation. Endogenic sources of sulfurous material may also contribute. This work was supported by NASA's Planetary Geology and Geophysics Program.

Carlson, R. W.

2001-11-01

357

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

SciTech Connect

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

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

1999-11-18

358

Separation of hafnium from zirconium in sulfuric acid solutions using pressurized ion exchange  

SciTech Connect

High-resolution pressurized ion exchange has been used successfully to study and separate hafnium and zirconium sulfate complexes by chromatographic elution from Dowex 50W-X8 (15 to 25 ..mu..m) resin with sulfuric acid solutions. Techniques were developed to continuously monitor the column effluents for zirconium and hafnium by reaction with fluorometric and colorimetric reagents. Since neither reagent was specific for either metal ion, peak patterns were initially identified by using the stable isotopes /sup 90/Zr and /sup 180/Hf as fingerprints of their elution position. Distribution ratios for both zirconium and hafnium decrease as the inverse fourth power of the sulfuric acid concentration below 2N and as the inverse second power at higher acid concentration. The hafnium-to-zirconium separation factor is approximately constant (approx. 8) over the 0.5 to 3N range. Under certain conditions, an unseparated fraction was observed that was not retained by the resin. The amount of this fraction which is thought to be a polymeric hydrolysis product appears to be a function of metal and sulfuric acid concentrations. Conditions are being sought to give the highest zirconium concentration and the lowest acid concentration that can be used as a feed material for commercial scale-up in the continuous annular chromatographic (CAC) unit without formation of the polymer.

Hurst, F.J.

1981-01-01

359

Iron Dissolution of Dust Source Materials during Simulated Acidic Processing: The Effect of Sulfuric, Acetic, and Oxalic Acids.  

PubMed

Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface. PMID:23883276

Chen, Haihan; Grassian, Vicki H

2013-08-29

360

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

361

Effects of simulated sulfuric acid rain on crop plants  

Microsoft Academic Search

Since relatively little is known about the effects of acid precipitation on growth and productivity of crop plants, a crop survey was initiated to study effects of HSO rain simulants on growth, yield, and quality of selected crops which were chosen to represent diverse taxonomic groups and crop products. Plants were grown in pots in field-exposure chambers and subjected to

C. J. Cohen; L. C. Grothaus; S. C. Perrigan

1981-01-01

362

Investigation on copper corrosion in thin films of sulfuric acid  

Microsoft Academic Search

The conditions for copper corrosion were investigated with regard to its use as the negative grid material in high performance lead-acid batteries with gelled electrolyte. The experiments on copper sheets show that only under very extreme conditions, when there is a thin electrolyte film on the surface and no lead coating over a distance of more than about 3 mm,

Rainer Wagner

1996-01-01

363

Correlation of aerosol nucleation rate with sulfuric acid and ammonia in Kent, Ohio: An atmospheric observation  

NASA Astrophysics Data System (ADS)

New particle formation (NPF) occurs in various atmospheric environments, and these newly formed particles have the potential to grow to cloud condensation nuclei. But at present it is unclear which chemical species are involved in aerosol nucleation and growth, in part because there are only a limited number of simultaneous measurements of aerosol precursors and aerosol size distributions. Observations of ambient aerosol size distributions, sulfuric acid, and ammonia were made for over a year in Kent, Ohio, a relatively less polluted continental environment. Particle sizes in the diameter range from 3 to 1000 nm were measured continuously through the whole year, while sulfuric acid and ammonia were measured seasonally with two chemical ionization mass spectrometers. Strong NPF events were more frequently found during the spring and fall and less frequently during the summer and winter. The median of measured sulfuric acid was higher in spring (5.2 106 cm-3) and summer (2.9 106 cm-3) than in winter (6 105 cm-3) and fall (5 105 cm-3). We have used the inverse model Particle Growth and Nucleation to derive aerosol nucleation and growth rates from the measured aerosol size distributions. Nucleation rates derived during the NPF events ranged from 1.4 to 12.9 cm-3 s-1 and were proportional to the measured sulfuric acid concentration with a power of 0.6-2.3. Our results show that sulfuric acid is an important aerosol nucleation precursor, but only a small fraction of the aerosol growth rates could be explained by the condensation of sulfuric acid alone. Ammonia mixing ratios did not have a diurnal trend but had some seasonal variations, higher in spring than in fall and winter, typically at sub-ppbv level; aerosol nucleation rates did not show a clear correlation with ammonia at least at this sub-ppbv level at sub-ppbv level, mostly because the ammonia mixing ratios were nearly constant. Our observations also indicate that the role that ammonia plays in aerosol nucleation is more complicated than is currently understood by the aerosol nucleation theories.

Erupe, Mark E.; Benson, David R.; Li, Jingmin; Young, Li-Hao; Verheggen, Bart; Al-Refai, Mohammed; Tahboub, Omar; Cunningham, Victoria; Frimpong, Flavia; Viggiano, Albert A.; Lee, Shan-Hu

2010-12-01

364

The role of surface sulfur species in the inhibition of pyrrhotite dissolution in acid conditions  

NASA Astrophysics Data System (ADS)

Pyrrhotite, in anoxic acidic conditions, exhibits an induction period before rapid dissolution occurs. The length of the induction period is controlled by the amount of surface oxidation products on the mineral surface, acid strength, and temperature. During the induction period there is slow release of iron but little or no production of H 2S. The induction period is best described as a period of inhibited dissolution, before the onset of H 2S production and increased rate of iron release of at least 2 orders of magnitude. X-ray photoelectron spectroscopic (XPS) analysis of the acid-reacted surface shows the progress of the dissolution. Four stages of dissolution have been identified. (1) The immediate dissolution of an outermost layer of oxidised iron hydroxide/oxyhydroxide species and oxy-sulfur species. (2) Inhibited, diffusion limited dissolution during an induction period due to iron diffusion through the metal-deficient layer and oxidative dissolution of the polysulfide species. (3) Rapid, acid-consuming reaction of mono-sulfide species under nonoxidative or reductive conditions with production of H 2S. (4) Inhibited dissolution due to reoxidation of the sulfide surface by oxidising solution species (i.e., Fe 3+, residual oxygen) to produce polysulfide, elemental sulfur, and oxy-sulfur species. Dissolving synthetic pyrrhotite in similar, but aerated, acidic conditions, results in inhibited dissolution characterised by a lower rate of Fe release, minimal release of SO 42- and no release of H 2S . The XPS sulfur (S2p) spectrum shows sulfate and a form of elemental sulfur on the reacted surface. Only the first two stages of dissolution occur. The second stage differs in this case in that there is a plentiful supply of oxidising species (O 2). Two reaction mechanisms are proposed for the dissolution of the iron sulfide lattice of pyrrhotite in acidic conditions. The mechanisms are oxidative and nonoxidative dissolution. Two distinct activation energies are associated with the two regimes. A lower activation energy corresponds to inhibited dissolution with no production of H 2S. A t 1/2 rate law describes dissolution in air saturated solutions and supports diffusion controlled dissolution under these conditions. A higher activation energy corresponds to rapid dissolution with H 2S production. The mechanism of dissolution is determined by the state of the surface, particularly the sulfur species.

Thomas, Joan E.; Jones, Colin F.; Skinner, William M.; Smart, Roger St. C.

1998-05-01

365

ADVANCED SULFUR CONTROL CONCEPTS  

Microsoft Academic Search

Conventional sulfur removal in integrated gasification combined cycle (IGCC) power plants involves numerous steps: COS (carbonyl sulfide) hydrolysis, amine scrubbing\\/regeneration, Claus process, and tail-gas treatment. Advanced sulfur removal in IGCC systems involves typically the use of zinc oxide-based sorbents. The sulfides sorbent is regenerated using dilute air to produce a dilute SO (sulfur dioxide) tail gas. Under previous contracts the

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

2003-01-01

366

Stability of Supported Platinum Sulfuric Acid Decomposition Catalysts for use in Thermochemical Water Splitting Cycles  

SciTech Connect

The activity and stability of several metal oxide supported platinum catalysts were explored for the sulfuric acid decomposition reaction. The acid decomposition reaction is common to several sulfur based thermochemical water splitting cycles. Reactions were carried out using a feed of concentrated liquid sulfuric acid (96 wt%) at atmospheric pressure at temperatures between 800 and 850 C and a weight hour space velocity of 52 g acid/g catalyst/hr. Reactions were run at these high space velocities such that variations in kinetics were not masked by surplus catalyst. The influence of exposure to reaction conditions was explored for three catalysts; 0.1-0.2 wt% Pt supported on alumina, zirconia and titania. The higher surface area Pt/Al2O3 and Pt/ZrO2 catalysts were found to have the highest activity but deactivated rapidly. A low surface area Pt/TiO2 catalyst was found to have good stability in short term tests, but slowly lost activity for over 200 hours of continuous operation.

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

2007-03-01

367

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (Chlorophyta).  

PubMed

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva latuca was selected from the "Marine Park" in Tokyo Bay, and its growth rate (g-dry/[m2.d]) was measured using model reactors located on the land or on the surface of the sea at Yokohama. The growth rate of U. lactuca was recorded to be approx 20 g-dry/(m2.d), which is estimated to be 10 times greater than that in a natural field in the Marine Park. In addition, this growth rate was higher than that of conventional crops such as corn and rice on a farm or paddy. These data led us to newly design and propose a floating type of labor-efficient U. lactuca production system. d-Cysteinolic acid, which is included in U. lactuca as a major sulfur amino acid, inhibited the Fenton reaction, resulting in suppression of hydroxyl radical production and singlet oxygen. Addition of the sulfur amino acid (1 microM) to HepG2 cells markedly decreased the intracellular triglyceride level. Hence, this proposed facility also has the potential for industrial production of a valuable resource for the primary prevention of lifestyle-related diseases using enriched or eutrophied seawater. PMID:14981285

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

2004-02-01

368

Advanced sulfur control concepts  

Microsoft Academic Search

Regenerable metal oxide sorbents, such as zinc titanate, are being developed to efficiently remove hydrogen sulfide (HS) from coal gas in advanced power systems. Dilute air regeneration of the sorbents produces a tailgas containing a few percent sulfur dioxide (SO). Catalytic reduction of the SO to elemental sulfur with a coal gas slipstream using the Direct Sulfur Recovery Process (DSRP)

S. K. Gangwal; B. S. Turk; R. P. Gupta

1995-01-01

369

Sorption Model for Iron Dissolution in Inhibited Sulfuric Acid  

Microsoft Academic Search

The unusual behavior of halide ions and some organic additives in acidic solutions during anodic polarization has been observed and reported in the literature. In our paper this behavior is studied on ARMCO iron in 0.5 M H2SO4 solutions in the presence of iodide ions. Based on an earlier conception, a model is developed for the description of sorption processes

T. Horvth; E. Klmn

2002-01-01

370

Leaching of vanadium from LD converter slag using sulfuric acid  

Microsoft Academic Search

In order to extract vanadium from LD (LinzDonawitz) converter slag of steelmaking plant, an alkaline roastingacid leaching study was carried out and the effect of different parameters on the kinetics of vanadium dissolution was determined. The leaching residue was characterized by XRD, XRF and SEM\\/EDX analyzer. The maximum vanadium recovery of ca. 95% was achieved at the optimum leaching condition

M. Aarabi-Karasgani; F. Rashchi; N. Mostoufi; E. Vahidi

2010-01-01

371

Mineralogical Controls on Microbial Diversity in a Sulfuric Acid Karst System  

NASA Astrophysics Data System (ADS)

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

Jones, A. A.; Bennett, P.

2011-12-01

372

Organic reactions increasing the absorption index of atmospheric sulfuric acid aerosols  

NASA Astrophysics Data System (ADS)

Unlike most environments present at Earth's surface atmospheric aerosols can be favorable to organic reactions. Among them, the acid-catalyzed aldol condensation of aldehydes and ketones produces light-absorbing compounds. In this work the increase of the absorption index of sulfuric acid solutions 50-96 wt. % resulting from the uptake of gas-phase acetaldehyde, acetone, and 2-butanone (methyl ethyl ketone), has been measured in the near UV and visible range. Our results indicate that the absorption index between 200 and 500 nm for stratospheric sulfuric aerosols exposed to 100 pptV of acetaldehyde (1 pptV = 10-12 v/v) would increase by four orders of magnitude over a two-year lifetime. Rough estimates based on previous radiative calculations suggest that this reaction could result in an increase of the radiative forcing of sulfate aerosols of the order of 0.01 W m-2, and that these processes are worth further investigation.

Nozire, B.; Esteve, W.

2005-02-01

373

Composite Film Formation on Iron in Sulfuric Acid by Bismuth(III) Chloride and Benzyl Thiocyanate  

Microsoft Academic Search

A synergistic inhibitory effect of bismuth(3) chloride and benzyl thiocyanate (C[sub 6]H[sub 5]CH[sub 2]SCN) on corrosion of iron (Fe) in 1 N sulfuric acid was investigated using polarization and impedance measurements. A composite protective film formed on the Fe surface by a combination of both compounds. The film was analyzed by x-ray photo-electron spectroscopy and electron probe microanalysis. Inhibition efficiency

M. Ohi; H. Nishihara; K. Aramaki

1994-01-01

374

Effect of KI on improving copper corrosion inhibition efficiency of benzotriazole in sulfuric acid electrolytes  

SciTech Connect

A synergistic effect exists when benzotriazole (BTAH) and iodide ions are used together to prevent the corrosion of copper in sulfuric acid. The nature of this effect has been studied systematically by using electrochemical techniques and X-ray photoelectron spectroscopy. The synergistic effect is due largely to the formation of a film of Cu(IBTA) complex and is probably polymeric in nature. This new complex film greatly depresses copper dissolution.

Wu, Y.C.; Zhang, P.; Pickering, H.W.; Allara, D.L. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering)

1993-10-01

375

Epas Catalyst Research Program: Environmental Impact of Sulfuric Acid Emissions  

Microsoft Academic Search

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 H2SO4, averaging 2.7 mg\\/mile for 49-state cars and 15 mg\\/mile for California cars. Research on measurement methodology for H2SO4 and other sulfate

Robert E. Lee Jr; F. Vandiver Duffield

1977-01-01

376

Pressure oxidation kinetics of orpiment (As 2S 3) in sulfuric acid  

Microsoft Academic Search

Pressure oxidation kinetics of a massive orpiment (As2S3) sample in sulfuric acid solution were systematically investigated. The effects of temperature (170 to 230C), mean particle size (48 to 125?m diameter) and oxygen partial pressure (345 to 1035kPa) were evaluated. Oxidation rates were found to be affected significantly by changes in temperature and particle size, but were relatively insensitive to changes

Hu Long; David G. Dixon

2007-01-01

377

Behaviour of southern red oak hemicelluloses and lignin in a mild sulfuric acid hydrolysis  

Microsoft Academic Search

Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w\\/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150 degrees C in 38 minutes and to extend the hydrolysis; 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded

A. V. Tran; R. P. Chambers

1986-01-01

378

Sulfuric acid aerosol followed by ozone exposure in healthy and asthmatic subjects  

SciTech Connect

These studies evaluated symptom and pulmonary function responses of humans sequentially exposed to sulfuric acid aerosol and ozone. Thirty healthy subjects and 30 allergic asthmatic subjects underwent 3-hr exposures in an environmental chamber to 100{mu}g/m{sup 3} sulfuric acid and sodium chloride (control) aerosols (in random order), followed 24 hr later by 3-hr exposures to ozone (0.08, 0.12, or 0.18 ppm). Each subject was studied four times, receiving each aerosol preexposure followed by two of the three ozone concentrations. For the healthy group, no convincing symptomatic or physiologic effects of exposure to either the aerosol or ozone on lung function were found. For the asthmatic group, preexposure to sulfuric acid altered the pattern of response to ozone in comparison with sodium chloride preexposure and appeared to enhance the small mean decrements in FVC that occurred in response to 0.18 ppm ozone (means {+-}SE: -3.6 {+-}1.5% with sodium chloride preexposure, -6.8 {+-} 1.7% with sulfuric acid preexposure). Individual responses among asthmatic subjects were quite variable, some demonstrating reductions in FEV of more than 35% following ozone exposure. Analysis of variance of changes in FVC revealed evidence for interactions between aerosol and ozone exposure both immediately after (P = 0.005) and 4 hr after (P = 0.030) exposure. Similar effects were seen for FEV. When normal and asthmatic subjects were combined, four-way analysis of variance revealed an interaction between ozone and aerosol for the entire group (P = 0.0022) and a difference between normal and asthmatic subjects (P = 0.0048). There was no significant effect of exposures on symptoms for either normal or asthmatic subjects. Asthmatic subjects differ from healthy volunteers in their functional responses following sequential exposures to aerosols and ozone and appear to represent a susceptible population. 33 refs., 6 figs., 4 tabs.

Frampton, M.W.; Morrow, P.E.; Cox, C. [Univ. of Rochester School of Medicine and Dentistry, NY (United States)] [and others

1995-04-01

379

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

380

Heterogeneous interaction of formaldehyde with cold sulfuric acid: Implications for the upper troposphere and lower stratosphere  

Microsoft Academic Search

Laboratory studies of formaldehyde uptake on thin sulfuric acid films indicate that HCHO can be taken up for long periods of time without saturation. Initial Henry's law solubility coefficients are large (H*=106-107Matm-1) at stratospheric temperatures. This uptake is due to rapid formation of HCHO(aq), CH2(OH)2, and possibly HOCH2OSO2(OH) in solution. Over a longer time period, steady-state uptake continues with gamma~0.002

Laura T. Iraci; Margaret A. Tolbert

1997-01-01

381

Oxide film formation on a microcrystalline Al alloy in sulfuric acid  

Microsoft Academic Search

The differences in the electrochemical behavior of a rapidly solidified, two-phase (matrix and dispersoid) Al-based alloy containing Fe, V, and Si (FVS0812 alloy) and the bulk form of its matrix and dispersoid phases were investigated in sulfuric acid. FVS0812 exhibited generally higher electrochemical activity than the matrix material due to the presence of the very active dispersoid phase in the

S. C. Thomas; V. I. Birss

1997-01-01

382

The role of molecular sulfuric acid hydrates in the nucleation and reactivity of atmospheric aerosol  

NASA Astrophysics Data System (ADS)

We have recently identified a number of new molecular sulfuric acid hydrates in condensed products from the heterogeneous SO_3/H_2O reaction, including a 1:1 H_2SO_4:H_2O complex and a hydrated H_2SO_4:H_2O polymer. These species show characteristic IR absorption spectra and their identification is supported by a number of computational studies. Measurements on thin films of ionic sulfuric acid hydrates reveal that these species are present only on the surface, stabilising the interface between the ionic bulk and the ambient gas phase. Reactions with NH_3suggest that they are more reactive than the bulk components with adsorbing basic gases. The 1:1 complex observed in thin films has also been identified in concentrated liquid sulfuric acid aerosol. This species forms spontaneously, although it is only observed in significant concentrations at low temperatures and under relatively anhydrous conditions. Theoretical studies and microwave spectroscopic observations confirm that this species is the most stable product from the reaction of gaseous SO_3 and H_2O, which is known to be second order with respect to water. It seems likely therefore that this material plays a role in the initial nucleation and subsequent growth of sulfuric acid aerosol particles. We conclude that the surface of solid and liquid atmospheric aerosol particles may therefore have a molecular composition which is rather different to that of the particle bulk. Since these species are also observed to be more reactive than their ionic counterparts towards NH_3, their presence may play a role both in the nucleation of new aerosol from ternary mixtures, i.e. (SO_3/H_2O/NH_3 and their NO_y analogues) and the subsequent surface reactions of these particles.

Couling, S.; Horn, A.

2003-04-01

383

Dependence of nucleation rates on sulfuric acid vapor concentration in PoValley, Italy  

Microsoft Academic Search

A field campaign was conducted at the polluted rural site, San Pietro Capofiume (SPC) in PoValley, Italy, from June 26th to July 12th 2009 in the framework of the EUCAARI (European integrated project on aerosol, cloud, climate, and air interactions) project. The gas-phase sulfuric acid concentrations were measured for the first time at SPC station during this campaign. Here we

Amar Hamed; Christian Pla-Dlmer; Thomas Elste; Georg Stange; Stefano Decesari; Claudio Carbone; Maria Cristina Facchini; Jorma Joutsensaari; Ari Laaksonen

2010-01-01

384

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

Microsoft Academic Search

Wind-blown rain, rain splash, and films of free moisture play important roles in the epidemiology of many plant diseases. The effects of simulated rain acidified with sulfuric acid were studied on several host-parasite systems. Plants were exposed in greenhouse or field to simulated rain of pH 3.2 0.1 or pH 6.0 0.2. Simulated rain of pH 3.2 resulted

D. S. Shriner

1977-01-01

385

Chronic exposure of rats to ozone and sulfuric acid aerosol: biochemical and structural responses  

Microsoft Academic Search

Groups of rats were exposed to either 0.12 or 0.20 ppm of ozone, 20, 100, or 150 ppm of sulfuric acid aerosol (0.4-0.8 ?m diameter), or their mixtures in whole body exposure chambers for up to 90 days. Matched control animals were exposed to filtered air in comparable chambers. The rats were examined biochemically and morphometrically for centriacinar fibrosis or

Jerold A. Last; Kent E. Pinkerton

1997-01-01

386

Assessment of toxicologic interactions resulting from acute inhalation exposure to sulfuric acid and ozone mixtures  

Microsoft Academic Search

Studies examining effects of air pollutants often use single compounds, while real world' exposures are to more than one chemical. Thus, it is necessary to assess responses following inhalation of chemical mixtures. Rabbits were exposed for 3 hr to sulfuric acid aerosol at 0, 50, 75, or 125 micrograms\\/m3 in conjunction with ozone at 0, 0.1, 0.3, or 0.6 ppm,

R. B. Schlesinger; J. T. Zelikoff; L. C. Chen; P. L. Kinney

1992-01-01

387

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

388

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

Microsoft Academic Search

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

A. Krten; L. Rondo; S. Ehrhart; J. Curtius

2011-01-01

389

Preparation, characterization and photocatalytic activity of sulfuric acid-modified titanium-bearing blast furnace slag  

Microsoft Academic Search

The feasibility of reducing Cr(VI) from the aqueous solution by sulfuric acid-modified titanium-bearing blast furnace slag (SATBBFS) as a photocatalyst was investigated. The photocatalysts were examined by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI) under UV-vis

Xue-fei LEI; Xiang-xin XUE

2010-01-01

390

Separation of dilute electrolytes in poly(amino acid) functionalized microporous membranes: model evaluation and experimental results  

Microsoft Academic Search

Pressure-driven transport of dilute electrolytes in microporous membranes containing terminally-anchored charged poly(amino acids) (PAA) has been investigated through both experimental characterization and model evaluation. The membrane pore structure was modified via single-point covalent attachment of either negatively (poly(l-glutamic acid) or PLGA) or positively-charged polypeptides (poly(l-arginine) or PLA and poly(l-lysine) or PLL) allowing for separations using microporous materials (i.e. cellulosic, silica\\/polyethylene

Aaron M. Hollman; Noah T. Scherrer; A. Cammers-Goodwin; D. Bhattacharyya

2004-01-01

391

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

392

Minimization of artifacts in sulfuric acid mist measurement using NIOSH Method 7903.  

PubMed

NIOSH Method 7903 employs a silica gel tube for sulfuric acid mist measurement in workplaces. However, SO2 gas present in the sample volume can be transformed into sulfate in the sampling process causing an artifact that is reported as sulfuric acid. A sampling train incorporating a honeycomb denuder system was applied for field sampling at seven phosphate fertilizer plants to evaluate its use for reducing the artifact sulfate concentration while preserving the actual sulfuric acid mist concentration. The denuder system was designed to remove SO2 gas before the air entered the silica gel tube and to monitor SO2 concentration at the same time. A deactivation model was also applied to correct for the presence of the artifact. The denuder system had 95.7 +/- 6.8% collection efficiency for SO2 gas, and the impact of sulfate aerosol on SO2 collection was negligible. SO2 concentrations at the seven plants ranged from 34 ppb to 5.6 ppm. The honeycomb denuder system and the deactivation model were shown to reduce the artifact sulfate concentration by 70% and 39%, respectively. However, they were still higher than the sulfate aerosol concentration measured by a cascade impactor. One possible reason is the residual sulfate in the glass fiber filter and the silica gel. PMID:18754495

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

2008-08-01

393

Leaching of Chalcopyrite Concentrate with Hydrogen Peroxide and Sulfuric Acid in an Autoclave System  

NASA Astrophysics Data System (ADS)

In this study, leaching of chalcopyrite concentrate was investigated in an autoclave system using hydrogen peroxide and sulfuric acid. By decomposition of hydrogen peroxide, the active oxygen formed can provide both high oxidation potential and high pressure in a closed vessel for leaching. Preliminary studies showed that hydrogen peroxide can be used as an oxidant instead of oxygen gas in the autoclave. Central composite design (CCD) was used to examine the effects of the experimental parameters on the copper and iron extraction as a response. The proposed model equation using CCD showed good agreement with experimental data, the correlation coefficients R 2 for copper and iron being 0.84 and 0.86, respectively. The optimum conditions to obtain the main goal of maximum copper and minimum iron extraction from chalcopyrite were determined as to be sulfuric acid concentration of 2.5 M, hydrogen peroxide concentration of 2.3 M, leaching time of 24 minutes, chalcopyrite amount of 3.17 g (in 50-mL solution), stirring speed of 630 rpm, and leaching temperature of 351 K (78 C). Under the optimum condition, 76 pct of copper and 9 pct of iron were extracted from chalcopyrite concentrate. Extraction yield results of metals indicate that selective leaching of chalcopyrite can be achieved using hydrogen peroxide and sulfuric acid in an autoclave system.

Turan, M. Deniz; Altundo?an, H. Soner

2013-08-01

394

Leaching of Chalcopyrite Concentrate with Hydrogen Peroxide and Sulfuric Acid in an Autoclave System  

NASA Astrophysics Data System (ADS)

In this study, leaching of chalcopyrite concentrate was investigated in an autoclave system using hydrogen peroxide and sulfuric acid. By decomposition of hydrogen peroxide, the active oxygen formed can provide both high oxidation potential and high pressure in a closed vessel for leaching. Preliminary studies showed that hydrogen peroxide can be used as an oxidant instead of oxygen gas in the autoclave. Central composite design (CCD) was used to examine the effects of the experimental parameters on the copper and iron extraction as a response. The proposed model equation using CCD showed good agreement with experimental data, the correlation coefficients R 2 for copper and iron being 0.84 and 0.86, respectively. The optimum conditions to obtain the main goal of maximum copper and minimum iron extraction from chalcopyrite were determined as to be sulfuric acid concentration of 2.5 M, hydrogen peroxide concentration of 2.3 M, leaching time of 24 minutes, chalcopyrite amount of 3.17 g (in 50-mL solution), stirring speed of 630 rpm, and leaching temperature of 351 K (78 C). Under the optimum condition, 76 pct of copper and 9 pct of iron were extracted from chalcopyrite concentrate. Extraction yield results of metals indicate that selective leaching of chalcopyrite can be achieved using hydrogen peroxide and sulfuric acid in an autoclave system.

Turan, M. Deniz; Altundo?an, H. Soner

2013-05-01

395

Experimental Insights into the Sulfuric Acid/Water Phase Diagram: Implications for Polar Stratospheric Clouds  

NASA Astrophysics Data System (ADS)

We have investigated the H2SO4/H2O binary liquid/solid phase diagram using a highly sensitive differential scanning calorimeter (DSC) and infrared spectroscopy of thin films. In particular we have sought to investigate the region from pure ice to sulfuric acid hemihexahydrate (SAH, H2SO46.5H2O), including a detailed look at the sulfuric acid octahydrate (SAO). Our studies have found that there is a unique, repeatable IR spectra for SAO, which is not merely a combination of spectra of ice and sulfuric acid tetrahydrate (SAT), as has been previously suggested could be the case. From our DSC studies, we have identified the melting, or solid/solid phase transition of the octahydrate. We have also determined from our studies using the energy of fusion for SAO that SAO is a major component of H2SO4 solutions in the range 20 - 40 wt.% when they freeze. Our results indicate that SAO could be a significant portion of solid or partially frozen polar stratospheric cloud particles. As such, key stratospheric reactions should be studied on SAO surfaces.

Beyer, K. D.; Hansen, A. R.

2002-05-01

396

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

PubMed

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 Hyytil 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; Lnn, Gustaf; Ehn, Mikael; Lehtipalo, Katrianne; Dommen, Josef; Ehrhart, Sebastian; Ortega, Ismael K; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Hutterli, Manuel; Duplissy, Jonathan; Almeida, Joo; Amorim, Antonio; Breitenlechner, Martin; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Kajos, Maija; Keskinen, Helmi; Kirkby, Jasper; Kupc, Agnieszka; Krten, Andreas; Kurtn, Theo; Laaksonen, Ari; Mathot, Serge; Onnela, Antti; Praplan, Arnaud P; Rondo, Linda; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Sipil, Mikko; Tom, Antnio; Tsagkogeorgas, Georgios; Vehkamki, Hanna; Wimmer, Daniela; Baltensperger, Urs; Carslaw, Kenneth S; Curtius, Joachim; Hansel, Armin; Petj, Tuukka; Kulmala, Markku; Donahue, Neil M; Worsnop, Douglas R

2013-10-07

397

Effect of the trivalent iron content in a pyrrhotine concentrate on the reaction mechanism of its sulfuric acid leaching  

NASA Astrophysics Data System (ADS)

The laws of atmospheric sulfuric acid leaching of pyrrhotine concentrate are analyzed as a function of the redox potential of a reaction system, which is determined by the Fe(III) content in a solution.

D'yachenko, V. T.; Bryukvin, V. A.; Tsybin, O. I.

2012-01-01

398

Selective extraction of Cu\\/sup 2 +\\/ and Ag\\/sup +\\/ ions from sulfuric acid by synergistic combinations of tetradentate thia macrocycles with didodecylnaphthalene sulfonic acid  

Microsoft Academic Search

The aqueous-insoluble thia macrocycles tetrathia-14-crown-4 (TT14C4) and tetrathia-16-crown-4 (TT16C4) strongly and selectively synergize the extraction of Cu\\/sup 2 +\\/ and Ag\\/sup +\\/ ions from aqueous sulfuric acid solutions by the organophilic cation exchanger didodecylnaphthalene sulfonic acid (HDDNS) in toluene diluent. Over a range of sulfur acid concentrations, the selectivity is given by the order Ag\\/sup +\\/ > Cu\\/sup 2 +\\/

B. A. Moyer; C. L. Westerfield; W. J. McDowell; G. N. Case

1988-01-01

399

Selective Extraction of Cu and Ag Ions from Sulfuric Acid by Synergistic Combinations of Tetradentate Thia Macrocycles with Dioodecylnaphthalene Sulfonic Acid  

Microsoft Academic Search

The aqueous-insoluble thia macrocycles tetrathia-14-crown-4 (TT14C4) and tetrathia-16-crown-4 (TT16C4) strongly and selectively synergize the extraction of Cu and Ag ions from aqueous sulfuric acid solutions by the organophilic cation exchanger didodecylnaphthalene sulfonlc acid (HDDNS) in toluene diluent. Over a range of sulfuric acid concentrations, the selectivity is given by the order Ag > Cu > Mn, Fe, Fe, Co, Ni,

Bruce A. Moyer; Curtis L. Westerfield; W. J. Mcdowell; G. N. Case

1988-01-01

400

Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes  

Microsoft Academic Search

Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor\\u000a deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by\\u000a boiling in sulfuric acid solution. Various analytical techniques such as TGA\\/DSC, Raman spectroscopy, SEM, HRTEM and EDAX\\u000a were employed to investigate the morphology, graphitization and quality of

Seyedeh Z. Mortazavi; Abdul J. Novinrooz; Ali Reyhani; Soghra Mirershadi

2010-01-01

401

Cellulose Sulfuric Acid: Novel and Efficient Biodegradable and Recyclable Acid Catalyst for the Solid-State Synthesis of Thiadiazolo Benzimidazoles  

Microsoft Academic Search

An efficient method for the synthesis of 2-substituted benzimidazoles has been developed. In this method, benzo[c][1,2,5]thiadiazole-4,5-diamine was condensed with different aldehydes in the presence of cellulose sulfuric acid under solvent-free conditions by simple physical grinding of reactants using a mortar and pestle at room temperature. The methodology is mild, high-yielding, and green, and the catalyst could be easily recycled.

B. Suresh Kuarm; J. Venu Madhav; B. Rajitha; Y. Thirupathi Reddy; P. Narsimha Reddy; Peter A. Crooks

2011-01-01

402

Comparison of sulfuric and hydrochloric acids as catalysts in hydrolysis of Kappaphycus alvarezii (cottonii).  

PubMed

In this study, hydrolysis of marine algal biomass Kappaphhycus alvarezii using two different acid catalysts was examined with the goal of identifying optimal reaction conditions for the formation of sugars and by-products. K. alvarezii were hydrolyzed by autoclave using sulfuric acid or hydrochloric acid as catalyst with different acid concentrations (0.1-1.0 M), substrate concentrations (1.0-13.5%), hydrolysis time (10-90 min) and hydrolysis temperatures (100-130 ()C). A difference in galactose, glucose, reducing sugar and total sugar content was observed under the different hydrolysis conditions. Different by-product compounds such as 5-hydroxymethylfurfural and levulinic acid were also observed under the different reaction conditions. The optimal conditions for hydrolysis were achieved at a sulfuric acid concentration, temperature and reaction time of 0.2 M, 130 C and 15 min, respectively. These results may provide useful information for the development of more efficient systems for biofuel production from marine biomass. PMID:21909670

Meinita, Maria Dyah Nur; Hong, Yong-Ki; Jeong, Gwi-Taek

2011-09-10

403

Sulfuric, hydrochloric, and nitric acid-catalyzed triacetone triperoxide (TATP) reaction mixtures: an aging study.  

PubMed

The organic peroxide explosive triacetone triperoxide (TATP) is regularly encountered by law enforcement agents in various stages of its production. This study utilizes solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) to examine sulfuric acid-, hydrochloric acid-, and nitric acid-catalyzed TATP syntheses during the initial 24 h of these reactions at low temperatures (5-9C). Additionally, aging of the reaction mixtures was examined at both low and ambient temperatures (19-21C) for a further 9 days. For each experiment, TATP could be readily identified in the headspace above the reaction mixture 1 h subsequent to the combination of reagents; at 24 h, TATP and diacetone diperoxide (DADP) were prominent. TATP degraded more rapidly than DADP. Additionally, chlorinated acetones chloroacetone and 1,1,-dichloroacetone were identified in the headspace above the hydrochloric acid-catalyzed TATP reaction mixture. These were not present when the catalyst was sulfuric acid or nitric acid. PMID:21595692

Fitzgerald, Mark; Bilusich, Daniel

2011-05-19

404

Heterogeneous chemistry of octanal and 2, 4-hexadienal with sulfuric acid  

NASA Astrophysics Data System (ADS)

Recent experimental studies using the environmental chamber have suggested that acid-catalyzed particle-phase reactions of organic carbonyls lead to multifold increases in secondary organic aerosol (SOA) mass, but the kinetics and mechanism of the heterogeneous chemistry of carbonyls with sulfuric acid remain largely uncertain. We report the first measurements of heterogeneous uptake of octanal and 2, 4-hexadienal on liquid H2SO4 in the acid range of 60 to 85 wt % and between 250 and 298 K. Octanal was physically absorbed by sulfuric acid without undergoing irreversible reaction. From the time-dependent uptake the effective Henry's law solubility constant (H*) was determined. Irreversible reactive uptake was observed for 2, 4-hexadienal, and the uptake coefficient decreased with decreasing acid concentrations. The uptake of octanal and 2, 4-hexadienal on liquid H2SO4 is explained by aldol condensation, dependent on acidity. The results suggest that aldol condensation of the aldehydes can be important in the upper troposphere, but may not significantly contribute to secondary organic aerosol formation in the lower troposphere.

Zhao, Jun; Levitt, Nicholas P.; Zhang, Renyi

2005-05-01

405

Formaldehyde instrument development and boundary layer sulfuric acid: Implications for photochemistry  

NASA Astrophysics Data System (ADS)

This work presents the development of a laser-induced fluorescence technique to measure atmospheric formaldehyde. In conjunction with the technique, the design of a compact, narrow linewidth, etalon-tuned titanium: sapphire laser cavity which is pumped by the second harmonic of a kilohertz Nd:YAG laser is also presented. The fundamental tunable range is from 690-1100 nm depending on mirror reflectivities and optics kit used. The conversion efficiency is at least 25% for the fundamental, and 2-3% for intracavity frequency doubling from 3.5-4W 532 nm pump power. The linewidth is <0.1 cm-1, and the pulsewidth is 18 nsec. Applications of this cavity include the measurement of trace gas species by laser-induced fluorescence, cavity ringdown spectroscopy, and micropulse lidar in the UV-visible region. Also presented are observations of gas-phase sulfuric acid from the NEAQS-ITCT 2K4 (New England Air Quality Study--- Intercontinental Transport and Chemical Transformation) field campaign in July and August 2004. Sulfuric acid values are reported for a polluted environment and possible nucleation events as well as particle growth within the boundary layer are explored. Sulfate production rates via gas phase oxidation of sulfur dioxide are also reported. This analysis allows an important test of our ability to predict sulfuric acid concentration and probe its use as a fast time response photochemical tracer for the hydroxyl radical, OH. In comparison, the NASA time-dependent photochemical box model is used to calculate OH concentration. Nighttime H2SO4 values are examined to test our understanding of nocturnal OH levels and oxidation processes. In comparison, sulfuric acid from a large ground based mission in Tecamac, Mexico (near the northern boundary of Mexico City) during MIRAGE-Mex field campaign (March 2006) is presented. This and other measurements are used to characterize atmospheric oxidation and predict sulfuric acid and OH concentrations at the site. The observations in conjunction with the NASA LARc Photochemical box model are used to explore ozone production, nitrate and sulfate formation, and radical levels and radical production rates during the day. The one minute observations of sulfuric acid, sulfur dioxide, and aerosol surface area were again used to calculate OH levels assuming steady state, and are in good agreement with observations of OH (R2 = 0.7). Photochemical activity is found to be a maximum during the morning hours, as seen in ozone and nitrate formation. Although the model predictions capture the observed diurnal profile, the model underpredicts RO2 concentrations in the morning hours and overpredicts in the afternoon (HO 2 + RO2 radical Model/observed (M/O) 1.15 and OH M/O 1.2).

Case Hanks, Anne Theresa

406

The chemical processing of gas-phase carbonyl compounds by sulfuric acid aerosols: 2,4-pentanedione  

Microsoft Academic Search

This work investigates the interactions between gas-phase carbonyl compounds and sulfuric acid aerosols. It focuses on understanding the chemical processes, giving a first estimate of their importance in the atmosphere, and suggesting directions for further investigations. The solubility and reactivity of a compound with a large enolization constant, 2,4-pentanedione, in water\\/sulfuric acid solutions 096wt% have been investigated at room temperature

Barbara Nozire; Daniel D Riemer

2003-01-01

407

Uptake of gas-phase ammonia. 2. Uptake by sulfuric acid surfaces  

SciTech Connect

Aerosols play an important role in the atmospheric chemistry of both the stratosphere and the troposphere. Aerosols also affect the earth's climate by directly scattering radiation, and indirectly, by serving as cloud condensation nuclei (CCN). The number of cloud droplets formed is directly proportional to the number density of cloud condensation nuclei. The size, density and composition of these cloud droplets in turn determine the effect of clouds on the Earth's albedo. The uptake of gas-phase ammonia by sulfuric acid surfaces was measured as a function of temperature (248--288 K), gas-liquid interaction time (2--15 ms), and acid concentration (20--70 wt% H{sub 2}SO{sub 4}) using a droplet train apparatus. The uptake coefficient increases as a function of acid concentration and reaches unity at about 55 wt% H{sub 2}SO{sub 4}. The increased NH{sub 3} uptake in acid solution is apparently due to reaction between NH{sub 3} and H{sup +} at the gas-liquid interface. The results yielded parameters required to model the reaction of NH{sub 3} with H{sup +} at the gas-liquid interface. These uptake experiments were expanded to include a detailed study of gas transport to a moving train of droplets. An analysis of previous sulfuric acid aerosol neutralization experiments shows that the uptake of ammonia by ternary NH{sub 3}-H{sub 2}SO{sub 4}-H{sub 2}O solutions is significantly lower than that by fresh binary H{sub 2}SO{sub 4}-H{sub 2}O solutions. At typical tropospheric water and ammonia vapor concentrations, NH{sub 3} uptake coefficients need to be included in detailed microphysical models of sulfuric acid aerosols.

Swartz, E.; Shi, Q.; Davidovits, P.; Jayne, J.T.; Worsnop, D.R.; Kolb, C.E.

1999-11-04

408

Minimizing sulfur contamination and rinse water volume required following a sulfuric acid/hydrogen peroxide clean by performing a chemically basic rinse  

SciTech Connect

Sulfuric acid hydrogen peroxide mixtures (SPM) are commonly used in the semiconductor industry to remove organic contaminants from wafer surfaces. This viscous solution is very difficult to rinse off wafer surfaces. Various rinsing conditions were tested and the resulting residual contamination on the wafer surface was measured. The addition of small amounts of a chemical base such as ammonium hydroxide to the rinse water has been found to be effective in reducing the surface concentration of sulfur and also mitigates the particle growth that occurs on SPM cleaned wafers. The volume of room temperature water required to rinse these wafers is also significantly reduced.

Clews, P.J.; Nelson, G.C.; Resnick, P.J.; Matlock, C.A.; Adkins, C.L.J.

1997-08-01

409

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

410

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

NASA Astrophysics Data System (ADS)

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

Tsona, Narcisse; Bork, Nicolai; Vehkamki, Hanna

2013-05-01

411

Measurements of the Hydroxyl Radical and Sulfuric Acid from the NOAA P3 during ITCT 2002  

NASA Astrophysics Data System (ADS)

A new chemical ionization mass spectrometer (CIMS) for measurement of OH and sulfuric acid was deployed on the ITCT 2002 mission. The wingpod mounted CIMS instrument weighed less than 600 lbs and used a total of less than 1 kW of 400 Hz power. Data was obtained on all of the science flights out of Monterey, CA. In general, very low OH number densities were observed on the flights that focused on high altitude transport of Asian pollution. On many occasions air parcels were intercepted containing enhanced levels of CO, NOy, and particulates. However, the OH levels in these air masses were very low and near the detection limit of the instrument of ~2e5 molec. cm-3. This result is consistent with the observed low dew points (TD< -240 K) and NOx concentrations. This conclusion will be tested by comparison to predictions by photochemical box models. The sulfuric acid number densities were also usually very low (<1e6 molec. cm-3) on these flights probably due to removal by cloud processing and uptake by particles during the week long transit time from Asia. However, on the 5/10/02 and 5/17/02 flights high levels of sulfuric acid strongly correlated with CO were observed in a few plumes of Asian origin. The P3 aircraft was also used to study the effects of ship emissions and pollutant transport into and out of West Coast metropolitan areas. Data from a good example of this type of experiment on May 8, 2002 will be presented. The first part of the flight was used to investigate ship emissions in the marine boundary layer and the last half explored San Francisco, Oakland and the Central Valley. During the ship plume study high levels of sulfuric acid (> 2e7 molec. cm-3) were observed that corresponded to transects of ship emission plumes. These sharp spikes were overlaid on a broad background of relatively high levels (> 5e6 molec. cm-3) of sulfuric acid in the marine boundary layer. This background level is much higher than in other portions of the marine boundary layer sampled on this mission and is approximately equal to the background levels in San Francisco or Los Angeles. These data along with elevated ozone, particulate sulfate and NOy values indicate that ship emissions are significantly perturbing the atmospheric chemistry of large portions of the marine boundary layer.

Huey, G.; Tanner, D.; Nowak, J.; Neuman, A.; Ryerson, T.; Nicks, D.; Brock, C.; Jakoubek, R.; Sullivan, A.; Orsini, D.; Holloway, J.; Dunlea, E.; Trainer, M.; Hubler, G.; Parrish, D.; Fehsenfeld, F.

2002-12-01

412

Hepatic metabolism of sulfur amino acids in db/db mice.  

PubMed

To determine the effect of type-2 diabetes and obesity on the hepatic metabolism of sulfur amino acids, hepatic sulfur amino acid metabolism was determined in db/db mice. Hepatic methionine was markedly decreased in db/db mice, although the hepatic activity of betaine homocysteine methyltransferase was increased. The decrease in hepatic methionine was reflected by decreased sulfur-containing methionine metabolites, including S-adenosylmethionine, homocysteine, cysteine, and hypotaurine in liver and plasma. In contrast, S-adenosylhomocysteine, putrescine, and spermidine were increased in db/db mice. The hepatic level and activity of methionine adenosyltransferase I/III, an S-adenosylmethionine synthesizing enzyme, were significantly increased. These results suggest that increased polyamine synthesis, in conjunction with decreased hepatic methionine levels, is partly responsible for the reduction in hepatic S-adenosylmethionine. Decreased homocysteine in liver and plasma may be attributable to the decrease in hepatic methionine and upregulation of hepatic betaine homocysteine methyltransferase. Glutathione in liver and plasma did not change despite decreased ?-glutamylcysteine ligase activity. The decreased hepatic hypotaurine may be attributable to the downregulation of cysteine dioxygenase. The major finding of this study is that db/db mice exhibited decreases in hepatic methionine and its sulfurcontaining metabolites. PMID:23220616

Yun, Kang Uk; Ryu, Chang Seon; Lee, Ji-Yoon; Noh, Jung-Ran; Lee, Chul-Ho; Lee, Hyun-Sun; Kang, Jong Soon; Park, Song Kyu; Kim, Bong-Hee; Kim, Sang Kyum

2012-12-05

413

Evidence for the probable presence of sulfur-containing fatty acids as minor constituents in canola oil  

Microsoft Academic Search

Three isomeric epithio stearic acids have been concentrated as possible minor sulfur-bearing components of unprocessed canola\\u000a oil. Chromatographic and mass spectral evidence is presented in support of these novel fatty acid structures, tentatively\\u000a identified as isomeric 9, 12; 8, 11; and 7, 10 epithio stearic acids, each with a methyl substituent on the ring.

R. C. Wijesundera; R. G. Ackman

1988-01-01

414

Sulfur amino acid auxotrophy in Micrococcus species isolated from human skin.  

PubMed

Since methionine and (or) cysteine are required by a large percentage of natural auxotrophic Micrococcus strains isolated from human skin, investigations were directed to determine the specific enzymes affected in sulfur amino acid biosynthesis. Known intermediates in the interrelated cysteine and methionine biosynthetic pathways were tested as growth stimulants. Based on these growth studies, sulfur amino acid auxotrophs were grouped into three cysteine classes and five methionine classes. Selected auxotrophs of M. luteus had deficiencies in ATP sulfurylase (EC 2.7.7.4) and adenosine-5-sulfatophosphate (APS) kinase (EC 2.7.1.25), sulfite reductase (EC 1.8.1.2), serine transacetylase (EC 2.3.1.30), or beta-cystathionase (EC 4.4.1.8) activity; auxotrophs of M. lylae had deficiencies in sulfite reductase and serine transacetylase, beta-cystathionase, or N5, N10-methyltetrahydrofolate reductase (EC 1.1.1.68) activity; all auxotrophs of M. sedentarius tested had deficiencies in N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. nishinomiyaensis had deficiencies in adenosine-3-phosphate-5-sulfatophosphate (PAPS) reductase, sulfite reductase, serine transacetylase, or N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. varians had deficiencies in APS kinase, PAPS reductase, sulfite reductase, homoserine omicron-transsuccinylase, beta-cystathionase, or N5,N10-methyltetrahydrofolate reductase activity; auxotrophs of M. kristinae had deficiencies in serine transacetylase or cystathionine-gamma-synthase (EC 4.2.99.9) activity; auxotrophs of M. roseus had deficiencies in PAPS reductase, sulfite reductase, or serine transacetylase activity. Results of studies with various mutagens suggested that sulfur amino acid auxotrophy was primarily the result of a single base substitution in usually one or two of the genes controlling biosynthesis. A preliminary study of the amino acid composition of sweat suggested that this important source of nutrients does not contain adequate amounts of cysteine for the growth of cysteine auxotrophs but contains methionine that may be utilized in place of cysteine. PMID:188532

Farrior, J W; Kloos, W E

1976-12-01

415

Thermochemical Reduction Experiments of Native Sulfur, Sulfite, and Sulfate by Amino Acids at 150 - 200C  

NASA Astrophysics Data System (ADS)

We have conducted series of laboratory experiments to investigate geochemical characteristics (e.g., kinetics and sulfur isotope fractionations) of redox reactions between a variety of amino acids (alanine, glycine, hystidine, etc.) and native sulfur, sodium sulfite or sodium sulfate at 150 - 200C. While previous researchers failed to demonstrate thermochemical sulfate reduction (TSR) at temperatures below 230C using a variety of organic compounds (sugars, methane, xylene, etc), in our series of experiments, all S-species were reduced to H2S by amino acids without presence of initial H2S and at neutral pH (i.e., pH = 6) even at 150C. The reduction rates generally decreased: (a) from native sulfur, to sulfite, and to sulfate; (b) from simple amino acids to more complex amino acids, particularly with aromatic functional groups (e.g., histidine); and (c) with decreasing temperatures. The rates of sulfite and S0 reduction were, respectively, approximately 2 and 3 orders of magnitude faster than those of sulfate. The kinetic isotope effects (?34S = ?34SH2S - ?34Sreactant) generally increased with increasing valence of the starting S-compounds. However, they have very complex trends for particularly experiments using sulfate. They fluctuated between positive and negative in others, and continued to increase or decrease in some runs up to +10 or -10 per mil. These variations likely associated with changes in S/C ratios of initial mixtures, and probably occurred because the generation of reductants (i.e., CH4, H2, and NH4+) from the solid mixtures varied; the kinetic isotope effects associated with sulfate reduction by NH4+ may be quite different from those associated with reduction by H2 and/or CH4. The ?^{33}S values of run products (H2S) generally increased from +0.16 per mil to +0.61 per mil with decreasing rates of sulfate reduction.

Naraoka, H.; Watanabe, Y.; Ohmoto, H.

2006-12-01

416

Kinetic study of esterification of sulfuric acid with alcohols in aerosol bulk phase  

NASA Astrophysics Data System (ADS)

In this study, we hypothesize that the formation of organosulfates through the reactions between sulfuric acid and alcohols in the aerosol bulk phase is more efficient than that in solution chemistry. To prove this hypothesis, the kinetics of the organosulfate formation was investigated for both aliphatic alcohol with single OH group (e.g., 1-heptanol) and the multialcohols ranging from semivolatiles (e.g., hydrated-glyoxal and glycerol) to nonvolatiles (e.g., sucrose) using analytical techniques directly monitoring aerosol bulk phase. Both the forward (k1) and the backward (k-1) reaction rate constants of organosulfate formation via the particle phase esterification of 1-heptanol with sulfuric acid were estimated using a Fourier Transform Infrared (FTIR) spectrometer equipped with a flow chamber under varying humidities. Both k1 and k-1 are in orders of 10-3 L mol-1 min-1, which are three orders of magnitude higher than the reported values obtained in solution chemistry. The formation of organosulfate in the H2SO4 aerosol internally mixed with multialcohols was studied by measuring the proton concentration of the aerosol collected on the filter using a newly developed Colorimetry integrated with a Reflectance UV-Visible spectrometer (C-RUV). The formation of organosulfate significantly decreases aerosol acidity due to the transformation of H2SO4 into dialkylsulfates. The forward reaction rate constants for the dialkylsulfate formation in the multialcohol-H2SO4 aerosols were also three orders of magnitude greater than the reported values in solution chemistry. The water content (MH2O) in the multialcohol-H2SO4 particle was monitored using the FTIR spectrometer. A large reduction of MH2O accords with the high yield of organosulfate in aerosol. Based on this study, we conclude that organosulfate formation in atmospheric aerosol, where both alcohols and sulfuric acid are found together, is significant.

Li, J.; Jang, M.

2013-09-01

417

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

418

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

419

Effect of 1,4-butynediol on the corrosion of steels in sulfuric and hydrochloric acids  

SciTech Connect

Samples of steels BSt. 1-KP, St. 35, St. 3, and Kh181OT were investigated over the temperature 20 to 80/sup 0/C for corrosion in 200 g/l sulfuric acid and in hydrochloric acid. A corrosion inhibitor, 1,4-butynediol at 2.5 g/l was also added to these mixtures, simultaneously. A gravimetric method was used for evaluation, and the length of exposure was 2 h. An investigation into the corrosion protection at (80/sup 0/C) afforded to St. 3 in sulfuric acid by the inhibitor indicates that its action is more effective in this medium than it is in hydrochloric acid. A similar relationship is observed for Kh181OT steel, but the inhibitor is more effective. Data for dependence of the corrosion rate and optimum concentration of the inhibitor on temperature, is presented for the various steel samples. The activation energy is reduced in the presence of the inhibitor, indicating chemisorption and a diffusion mechanism. 4 references, 4 figures, 4 tables.

Anoshchenko, I.P.; Luk'yanova, G.I.; Melnik, T.Ya.

1983-08-01

420

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

421

Sulfuric acid speleogenesis of Carlsbad Cavern and its relationship to hydrocarbons, Delaware basin, New Mexico and Texas  

SciTech Connect

Sulfur-isotope data and pH-dependence of the mineral endellite support the hypothesis that Carlsbad Cavern and other caves in the Guadalupe Mountains were dissolved primarily by sulfuric acid rather than by carbonic acid. Floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in {sup 32}S; {delta}{sup 34}S values as low as {minus}25.8 {per thousand} (CDT) indicate that the cave sulfur and gypsum are the end products of microbial reactions associated with hydrocarbons. A model for a genetic connection between hydrocarbons in the basin and caves in the Guadalupe Mountains is proposed. As the Guadalupe Mountains were uplifted during the late Pliocene-Pleistocene, oil and gas moved updip in the basin. The gas reacted with sulfate anions derived from dissolution of the Castile anhydrite to form H{sub 2}S, CO{sub 2}, and castile limestone. The hydrogen sulfide rose into the Capitan reef along joints, forereef carbonate beds, or Bell Canyon siliciclastic beds and there reacted with oxygenated groundwater to form sulfuric acid and Carlsbad Cavern. A sulfuric-acid mode of dissolution may be responsible for large-scale porosity of some Delaware basin reservoirs and for oil-field karst reservoirs in other petroleum basins of the world. 8 figs.

Hill, C.A. (Cave Research Foundation, Albuquerque, NM (USA))

1990-11-01

422

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

PubMed

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

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

2013-07-31

423

Visualization of imbalances in sulfur assimilation and synthesis of sulfur-containing amino acids at the single-cell level.  

PubMed

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

Hoffmann, Kristina; Grnberger, Alexander; Lausberg, Frank; Bott, Michael; Eggeling, Lothar

2013-08-30

424

Conversion of waste cellulose to ethanol. Phase 2: Reaction kinetics with phosphoric acid  

Microsoft Academic Search

Waste cellulosic material can be hydrolyzed in dilute acid solution to produce fermentable sugars which can then be converted into ethanol. A laboratory investigation was made of the feasibility of using phosphoric acid as the hydrolysis catalyst. The hydrolysis reaction with phosphoric acid solutions was compared with the reaction employing the more conventional dilute sulfuric acid catalyst. The purpose of

M. B. Moeller; R. E. Isbell

1982-01-01

425

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

426

Effects of large (0. 9. mu. m) sulfuric acid aerosols on human pulmonary function  

SciTech Connect

The effects of sulfuric acid particle concentration (mass/volume) and ambient temperatures on pulmonary function of young male nonsmokers were examined. Subjects (n = 11) thrice repeated a sequence of 20-min exercise (ventilation approximately 30 liters/min) and 20-min sitting rest. Pre- and postexposure pulmonary function tests (forced vital capacity maneuvers, lung volumes, maximum voluntary ventilation, R/sub aw/, TGV, and helium-oxygen FVC) were measured. During the exposure and at 2 min after cessation of each exercise period, forced vital capacity tests (air and helium-oxygen) were performed. Each subject was exposed in random order to filtered air or 233, 418, or 939 ..mu..g/m/sub 3/ particulate sulfuric acid. Mass median diameter (MMD) was 0.90-0.93 ..mu..m, and geometric SD was 1.66-1.73. No major changes in pulmonary function related to sulfate were observed in these subjects. The only measurement to show a significant interaction across time (pre-post) and sulfate concentration was FEV /sub 1.0/, which was significantly decreased with exposure to 939 ..mu..g/m/sup 3/ sulfate. The magnitude of the decrease was not considered to be of physiological significance. These results indicate that, even with the added stress of the increased depth and volume of exercise ventilation, exposure to as much as 1 mg/m/sup 3/ of 1 ..mu.. for ..mu..m sulfuric acid aerosol for 2 hr has little if any effect on standard tests of lung function.

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

1982-06-01

427

Dependence of nucleation rates on sulfuric acid vapor concentration in PoValley, Italy  

NASA Astrophysics Data System (ADS)

A field campaign was conducted at the polluted rural site, San Pietro Capofiume (SPC) in PoValley, Italy, from June 26th to July 12th 2009 in the framework of the EUCAARI (European integrated project on aerosol, cloud, climate, and air interactions) project. The gas-phase sulfuric acid concentrations were measured for the first time at SPC station during this campaign. Here we examine the dependence of nucleation rate on sulfuric acid vapor concentrations in SPC. The apparent nucleation rate - i.e. formation rate of 3 nm particles - was directly determined from differential mobility particle sizer data. The nucleation rate at 1 nm (J1) was then calculated by accounting for the coagulation of the sub-3 nm clusters with large particles during their growth from 1 to 3 nm. The dependence of J1 on [H2SO4] was studied for each nucleation day individually and for all nucleation days as a whole. It is usually assumed that the dependence of nucleation rate on sulfuric acid concentration follows a simple power law model J1 = P [H2SO4]^n; where P is the prefactor containing chemical and physical information of the nucleation process, and n is the nucleation exponent. With the so called activation and kinetic nucleation mechanisms, n takes the values 1 and 2, respectively, and most field studies show n to fall between these two values. For the SPC data, the nucleation exponent was higher than 2 for both individual days and for all nucleation days as a whole. In the light of the obtained results we will discuss the nucleation mechanism, composition of the nucleation mode particles, and the role of other gases (such as ammonia and water vapor) in the formation of new particles in SPC in more detail.

Hamed, Amar; Pla-Dlmer, Christian; Elste, Thomas; Stange, Georg; Decesari, Stefano; Carbone, Claudio; Facchini, Maria Cristina; Joutsensaari, Jorma; Laaksonen, Ari

2010-05-01

428

Measurements of Sulfuric Acid in the Ohio Valley and New York City from NOAA P3 during ICARTT 2004  

NASA Astrophysics Data System (ADS)

Fast time response (t = 1s) measurements of sulfuric acid (H2SO4) were made from the NOAA P3 during the ICARTT field mission. This data is analyzed to probe our understanding of both day and night oxidation processes in high sulfur environments. In particular, the photochemistry of the sulfur rich Ohio Valley is investigated by comparing OH values derived from the rapid steady state of the SO2, H2SO4, and aerosol system to those predicted by a photochemical model. This approach allow us to compare very high time resolution OH data in an environment where NOx, hydrocarbons, and SO2 are highly variable. A similar approach is used to look at nighttime OH levels in both the Ohio Valley and New York City regions. In particular, the surprisingly high level of sulfuric acid observed in some NYC plumes will be examined.

Huey, G.; Trainer, M.; Tanner, D.; Crawford, J.; Chen, G.; Olson, J.; Ryerson, T.; Brock, C.; Wollney, A.; Parrish, D.; Holloway, J.; Brown, S.; Dube, W.

2005-12-01

429

Reaction of ClONO2 with HCl on NAT, NAD, and frozen sulfuric acid and hydrolysis of N2O5 and ClONO2 on frozen sulfuric acid  

Microsoft Academic Search

The reaction of ClONO2 with HCl on the nitric acid trihydrate (NAT) and dihydrate (NAD) and on frozen sulfuric acid solutions was studied as functions of reactant concentration and temperature representative of the stratosphere. A flow tube reactor equipped with a chemical ionization mass spectrometer detector was used. The measured reactive uptake coefficient shows a strong dependence on temperature at

D. R. Hanson; A. R. Ravishankara

1993-01-01

430

Recovery and pre-concentration of americium (III) from dilute acid solutions using an emulsion liquid membrane containing di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant  

Microsoft Academic Search

An emulsion liquid membrane (ELM) containing di-2-ethylhexylphosphoric acid (D2EHPA) as the carrier extractant and SPAN 80\\u000a as the surfactant was used to pre-concentrate Am3+ from dilute acid solutions. Effects of various factors such as: external phase pH, internal phase conditions, equilibration\\u000a time, D2EHPA concentration, SPAN 80 concentration, etc. on Am3+ mass transfer were investigated. Emulsion was broken by the addition

S. Chowta; P. K. Mohapatra; S. C. Tripathi; B. S. Tomar; V. K. Manchanda

2010-01-01

431

Inhibition of enzymatic browning of chlorogenic acid by sulfur-containing compounds.  

PubMed

The antibrowning activity of sodium hydrogen sulfite (NaHSO(3)) was compared to that of other sulfur-containing compounds. Inhibition of enzymatic browning was investigated using a model browning system consisting of mushroom tyrosinase and chlorogenic acid (5-CQA). Development of brown color (spectral analysis), oxygen consumption, and reaction product formation (RP-UHPLC-PDA-MS) were monitored in time. It was found that the compounds showing antibrowning activity either prevented browning by forming colorless addition products with o-quinones of 5-CQA (NaHSO(3), cysteine, and glutathione) or inhibiting the enzymatic activity of tyrosinase (NaHSO(3) and dithiothreitol). NaHSO(3) was different from the other sulfur-containing compounds investigated, because it showed a dual inhibitory effect on browning. Initial browning was prevented by trapping the o-quinones formed in colorless addition products (sulfochlorogenic acid), while at the same time, tyrosinase activity was inhibited in a time-dependent way, as shown by pre-incubation experiments of tyrosinase with NaHSO(3). Furthermore, it was demonstrated that sulfochlorogenic and cysteinylchlorogenic acids were not inhibitors of mushroom tyrosinase. PMID:22416853

Kuijpers, Tomas F M; Narvez-Cuenca, Carlos-Eduardo; Vincken, Jean-Paul; Verloop, Annewieke J W; van Berkel, Willem J H; Gruppen, Harry

2012-03-26

432

Ternary Nucleation of Sulfuric Acid, Water and Dimethylamine in the Cloud Experiment  

NASA Astrophysics Data System (ADS)

Galactic cosmic ray (GCR) variations were found to correlate with several past climate reconstructions. However, the microphysical mechanism responsible for this link remains mysterious. GCRs are thought to influence the formation of cloud condensation nuclei (CCN): an increased GCR flux could modify cloud properties, and therefore induce a cooling effect on the climate [Kirkby, 2007]. The formation of new particles from the cluster size and their growth to CCN has been investigated at the CLOUD (Cosmics Leaving OUtdoor Droplets) facility at CERN, which consists of a 26 m3 aerosol chamber exposed to an adjustable particle beam, reproducing GCR at different altitudes or latitudes. With state of the art instrumentation for particles of a few nanometers diameter as well as for trace gases, the nucleation of the sulfuric acid (H2SO4) - water (H2O) system, as well as the influence of ammonia (NH3) was already examined in the first experiments [Kirkby et al., 2011]. This paper presents the results on the nucleation of sulfuric acid in the presence of dimethylamine. Kirkby, J. (2007), Cosmic Rays and Climate, Surv Geophys, 28(5-6), 333-375, doi:10.1007/s10712-008-9030-6. Kirkby, J. et al. (2011), Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation, Nature, in press.

Praplan, A. P.; Bianchi, F.; Riccobono, F.; Dommen, J.; Weingartner, E.; Baltensperger, U.; Laboratory Of Atmospheric Chemistry; Cloud Consortium

2011-12-01

433

Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte  

Microsoft Academic Search

The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a\\u000a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4F\\/m2 in 18M H2SO4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions\\u000a (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however,

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

2006-01-01

434

Dynamic states of the Bray-Liebhafsky reaction when sulfuric acid is the control parameter  

NASA Astrophysics Data System (ADS)

Dynamic behavior of hydrogen peroxide decomposition catalyzed by iodate and hydrogen ions (the Bray-Liebhafsky reaction), in a continuous stirred tank reactor is investigated. The experimental results are obtained at one operational point in concentration phase space by varying mixed inflow concentrations of the sulfuric acid. The experimental evidences for the onset and termination of oscillatory behavior via the saddle node infinite period bifurcation as well as some kind of the Andronov-Hopf bifurcation are presented. In addition, the possibility of excitability of a stable steady state by thiamine was observed.

Peji?, N.; Maksimovi?, J.; Ribi?, D.; Kolar-Ani?, Lj.

2009-09-01

435

Detection of stratospheric sulfuric Acid aerosols with polarization lidar: theory, simulations, and observations.  

PubMed

The derivation of backscatter ratio profiles from polarization lidar measurements is discussed. The method is based on differences in depolarization between molecular backscattering and backscattering from spherical aerosol particles. Simulations show that the polarization algorithms yield backscatter ratios with uncertainties comparable with those obtained by Klett's method, provided that the backscattering process is dominated by molecular scattering. The technique could be utilized for monitoring the stratospheric sulfuric acid aerosol layer during periods of background conditions. The polarization analysis method is discussed in light of simulation results and is applied to polarization lidar profiles observed during the ALBATROSS 1996 field measurement campaign. PMID:18350097

Beyerle, G

2000-09-20

436

Stereospecific sulfur oxidation of 7-methylthioxanthone-2-carboxylic acid by Calonectria decora.  

PubMed Central

Thin-layer chromatography was used to determine the ability of three microorganisms capable of sulfur oxygenation, including Aspergillus niger, Streptomyces armentosus subsp. armentosus, and Calonectria decora, to oxidize 7-methylthioxanthone-2-carboxylic acid to the corresponding sulfoxide in growing cultures. In addition, optical rotary dispersion, circular dichroism, and nuclear magnetic resonance analysis in the presence of chiral shift reagent were used variously to access reaction stereoselectivity, absolute configuration, and optical purity of isolated products. The data indicated that C. decora produced the sulfoxide in high yield (69%) and optical purity (97%), most probably in the S-configuration.

Lanzilotta, R P; Bradley, D G; Maddox, M L

1977-01-01

437

Protective effect in sulfuric acid media of alumina and ceria oxide layers electrodeposited on stainless steel  

Microsoft Academic Search

The influence of thin layers of Al2O3 and Ce2O3CeO2, electrodeposited on stainless steel OC4004, on the corrosion behaviour of the systems Al2O3\\/SS, Ce2O3CeO2\\/SS and Al2O3Ce2O3CeO2\\/SS has been studied in sulfuric acid medium. A pronounced stabilizing effect on the passive state of steel and enhancement of its corrosion resistance has been established both for the samples as deposited and for the

D. Nickolova; E. Stoyanova; D. Stoychev; I. Avramova; P. Stefanov

2008-01-01

438

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

Microsoft Academic Search

Alternating current (AC) impedance measurements of mild steel\\/sulfuric acid interface in the absence and in the presence of\\u000a various concentrations of cystine (CysCys) have been carried out in the 100kHz10mHz frequency range. The results revealed\\u000a that CysCys is a good and effective inhibitor for mild steel corrosion in 0.5M H2SO4 and its percent inhibition efficiency changes with its concentration. Changes

Muzaffer zcan

2008-01-01

439

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

2013-10-02

440

Productivity of field-grown soybeans exposed to acid rain and sulfur dioxide alone and in combination  

Microsoft Academic Search

Sulfur dioxide (SO)-fumigated and unfumigated field plots of soybeans (Glycine max cv. Wells) were exposed to acid (pH 3.1) or control (pH approx.5.3) precipitation simulants to determine effects on growth and productivity. The precipitation simulants were applied at approximately 5-day intervals in July and August with a total of 3.4 cm applied in 1977 and 4.5 cm in 1978. Sulfur

P. M. Irving; J. E. Miller

1981-01-01

441

Using self-consistent energy surfaces to calculate the population distributions of neutral clusters and negatively charged clusters consisting of sulfuric acid and water  

NASA Astrophysics Data System (ADS)

We synthesize self-consistent Gibbs free energy surfaces for clusters of sulfuric acid, water, and bisulfate ions from a variety of sources including: a thermodynamic model of electrolyte solutions, the capillarity approximation, experimental measurements, and quantum chemical calculations. From these free energy surfaces, the equilibrium population distributions are calculated for neutral clusters of sulfuric acid and water and negatively charged clusters, consisting of sulfuric acid and water surrounding a bisulfate ion.

Smith, Jamison A.; Froyd, Karl D.; Toon, Owen B.

2013-05-01

442

Sulfur deficiency changes mycosporine-like amino acid (MAA) composition of Anabaena variabilis PCC 7937: a possible role of sulfur in MAA bioconversion.  

PubMed

In the present investigation we show for the first time that bioconversion of a primary mycosporine-like amino acid (MAA) into a secondary MAA is regulated by sulfur deficiency in the cyanobacterium Anabaena variabilis PCC 7937. This cyanobacterium synthesizes the primary MAA shinorine (RT = 2.2 min, lambda(max) = 334 nm) under normal conditions (PAR + UV-A + UV-B); however, under sulfur deficiency, a secondary MAA palythine-serine (RT = 3.9 min, lambda(max) = 320 nm) appears. Addition of methionine to sulfur-deficient cultures resulted in the disappearance of palythine-serine, suggesting the role of primary MAAs under sulfur deficiency in recycling of methionine by donating the methyl group from the glycine subunit of shinorine to tetrahydrofolate to regenerate the methionine from homocysteine. This is also the first report for the synthesis of palythine-serine by cyanobacteria which has so far been reported only from corals. Addition of methionine also affected the conversion of mycosporine-glycine into shinorine, consequently, resulted in the appearance of mycosporine-glycine (RT = 3.6 min, lambda(max) = 310 nm). Our results also suggest that palythine-serine is synthesized from shinorine. Based on these results we propose that glycine decarboxylase is the potential enzyme that catalyzes the bioconversion of shinorine to palythine-serine by decarboxylation and demethylation of the glycine unit of shinorine. PMID:20456655

Singh, Shailendra P; Klisch, Manfred; Sinha, Rajeshwar P; Hder, Donat-Peter

2010-04-26

443

Stability of carbon monoxide adsorbed on nanoparticle Pt and Pt\\/Ru electrodes in sulfuric acid media  

Microsoft Academic Search

Pt and Pt\\/Ru nanoparticle electrodes were used as substrates for studies of stability of chemisorbed CO and its interactions (exchange) with carbon monoxide and hydrogen gas admitted to sulfuric acid solution, which served as the supporting electrolyte for these measurements. The surface bound, radioactive CO was obtained after decomposition of 14C labeled methanol or formic acid from the same solution.

M. S. McGovern; P. Waszczuk; A. Wieckowski

2006-01-01

444

Respiratory tract lesions in guinea pigs exposed to sulfuric acid mist. [Mist is potential air pollutant from fossil fuel combustion  

Microsoft Academic Search

Guinea pigs were exposed in inhalation chambers to 25 mglm³ sulfuric acid mist 6 h\\/d for 2 d, and the acute respiratory effects were correlated by light and electron microscopy. This concentration of acid was selected since lower concentrations result in only slight effects while higher concentrations result in death. By light microscopy, the most prominent pulmonary lesion at 48

B. Y. Cockrell; W. M. Busey; F. L. Cavender

1978-01-01

445

Interim Proposal for Molecular Beam Studies of Surfactants in Sulfuric Acid Aerosols: Comparisons Between Hydrocarbon and Fluorocarbon Alcohols.  

National Technical Information Service (NTIS)

Heterogeneous reactions of gas phase molecules with aqueous sulfuric acid aerosols play a significant role in the destruction of ozone in the stratosphere. These processes include the acid-catalyzed reactions of HCI and HBr with CIONO2 (BrONO2) and HOCI (...

G. M. Nathanson

2003-01-01

446

Elemental Sulfur Reactions at Low Ph and Their Implication for Microbial Activity in Acid Mine Drainage Environments  

NASA Astrophysics Data System (ADS)

Elemental sulfur oxidation in low pH, oxic conditions is a key intermediate process governing the oxidation and acid generating potential of metal sulfide minerals. Nucleophilic reactions with aqueous sulfur intermediates, reactions with intermediate oxygen species, and oxidation reactions with ferric iron and/or oxygen are all important in considering how microorganisms utilize elemental sulfur for energy. A series of experiments investigating the kinetics of these reactions illustrates some of the requirements for sulfur-oxidizing microorganisms to utilize elemental sulfur in low pH environments. Surface area-normalized rates for the oxidation of elemental sulfur with molecular oxygen are on the order of 5 x 10-10 mol m-2 sec-1 at pH 1.5 and 1 x 10-8 mol m-2 sec-1 at pH 0.5. Ferric iron accelerates the rate by approximately a factor of 2, but this rate is independent of the ferric iron concentration over 2 orders of magnitude, within experimental error. Reactivity of elemental sulfur is not markedly different whether the sulfur is in the mineral structure or as a free S8 ring. Flocculation of small particles of elemental sulfur may severely limit the reactivity of this mineral in inorganic experiments. Surface infrared spectroscopy measurements did not show the development of any resolvable sulfur-oxygen bonds in 20 hours of reaction with 1 mM Fe3+, H2O2, or OH* (as Fenton's reagent) at pH 2. Observations of rate dependences from this study suggest that microbial utilization of elemental sulfur may be limited by a reaction involving the S8 ring, and not single S0 atoms in solution. The extremely low solubility of elemental sulfur in water and the tendency of small elemental sulfur grains to flocculate illustrate the potential importance of extracellular material as either a surfactant to import an S8 ring inside the cell or to facilitate a reaction to transform S8 into a more soluble and easily transported species. Changes in nucleophilicity of previously identified enzymes at low pH indicate that they would not function at low pH and therefore extracellular utilization of elemental sulfur must proceed by a different mechanism under these conditions. We will present some of the geochemical requirements for enzymatic function in low pH environments and report on current work towards identifying and characterizing enzymatic compounds that facilitate microbial functions in these environments.

Druschel, G. K.; Borda, M. J.; Luther, G. W.; Robert, H. J.; Banfield, J. F.