Effect Of Sulfuric Acid Concentration Research Articles

Hydrogen production from mushroom farm waste with a two-step acid hydrolysis process

The lignocellulosic material of mushroom farm waste was used as a feedstock owing to its quantity and availability in Taiwan. In the first stage, the lignocellulosic material of mushroom farm waste was converted into reduced sugars using concentrated sulfuric acid via hydrolysis with a one-step and/or a two-step process. The reduced sugars were then recovered by anion exchange resin. In the second stage, reduced sugars from the first stage were used as substrate to test the potential for biohydrogen production in a batch system. The effects of sulfuric acid concentrations, reaction temperature, particle size, and two-step hydrolysis were investigated at the first pretreatment stage (mushroom farm waste hydrolysis). The reduced sugar concentrations and the initial pH were investigated in the second stage (biohydrogen production). It was found that the maximum yield of reduced sugars in hydrolyzate (reduced sugar per soluble cellulose, wt%) from the first-step (40 °C for 20 min with 55.0% acid) and the second-step (40 °C for 20 min with 6.9% acid) were 74.49% and 96.79%, respectively. In the second stage, the best hydrogen production yield and the hydrogen production rate were 2.52 mol H 2/g COD substrate and 4.38 L/L/d, respectively, were obtained initially with a pH 7.0, a temperature of 37 °C and initial reduced sugar concentration of 20 g of COD/L.

Study on the Hydrolysis of Corn Stalk and Photosynthetic Bacteria Group Fermentation Hydrogen Production

Hydrogen production of photosynthetic bacteria group (PSBG) was studied using corn stalk hydrolyzate as hydrogen production substrate. The effects of sulfuric acid concentration, hydrolysis pH values and hydrolysis temperature on hydrogen production were investigated. The optimum process conditions were as follows: the sulfuric acid concentration was 1%, hydrolysis pH value was 6.0 and the hydrolysis temperature was 110°C , respectively. Three hydrolyzate detoxification methods were compared. The method of calcium hydroxide obtained the optimal detoxification effect and the maximum hydrogen yield was 472 mL H2/ (L-medium).

Preparation and Characterization of Nanocrystalline Cellulose by Acid Hydrolysis of Cotton Linter

The purpose of this study was to use acid hydrolysis of cotton linter to generate nanocrystal-line cellulose (NCC). Based on a 2^4 factorial design, the effects of sulfuric acid concentration, temperature, hydrolysis time, and the solid/liquid ratio on the NCC yield were examined. NCC specimens obtained from different sulfuric acid concentrations were subjected to a battery of analyses, including dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), 13C solid-state nuclear magnetic resonance (13CSNMR), and a thermal gravimetric analysis (TGA) to probe the particle size distribution, morphology, functional group shifts, position of the carbon, and thermal degradation properties of the ensuing NCC. The results indicated that the sulfuric acid concentration and solid/liquid ratio at higher levels, and temperature and reaction time at lower levels were significantly conducive to increases in NCC yields. The main effects in diminishing order were the acid concentration, temperature, hydrolysis time, and solid/liquid ratio. Results of DLS and TEM observations suggested that the NCC had a size distribution centered around 20~200 nm, with length-to-width ratios ranging 1:1~1:30. The FTIR analysis indicated that absorption peaks at 1010~1080 and 1150~1260 cm^(-1) were derived from sulfate ester bonds on the cellulosic chains. Solid state 13CNMR spectra indicated that the C4 atoms along the cellulosic chain were shifted from 87.4 ppm to a lower magnetic domain, indicating the sulfonic ester bonding position. The TGA indicated that the lower-sulfuric-acid NCC specimen began step 1 weight loss at ca. 149℃, whereas its starting temperature of step 2 weight loss was generally higher than the mid- and high-acid NCC, at 337 and 205℃, respectively. The high-acid NCC only showed marked weight loss at 243℃. The study found that a sulfuric acid concentration of 60%, a solid/liquid ratio of 1:20, a hydrolysis temperature of 45℃, and a hydrolysis time of 5 min produced the best yield of 54.4%.

Kinetics of cotton cellulose hydrolysis using concentrated acid and fermentative hydrogen production from hydrolysate

The kinetics of cotton cellulose hydrolysis using concentrated sulfuric acid and the performance of fermentative hydrogen production from the hydrolysate in the batch system was carried out in this study. Effects of sulfuric acid concentrations, cotton cellulose concentrations and operating temperatures on the cotton cellulose hydrolysis were investigated. It was found that cotton cellulose can dissolve completely in sulfuric acid concentration above 55% (by volume) at room temperature. The reduced sugar yields were varied from 64.3 to 73.9% (g R-sugar/g cotton cellulose) with the initial cotton cellulose concentrations of 30–70 g/L at a temperature of 40 °C. The reduced sugar concentrations and the initial pH of biohydrogen production were investigated at 37 °C. It was found that the optimal values of the hydrogen yield and substrate utilization were 0.95 mol H 2/mol R-sugar and 98% with an initial pH of 8.2, when substrate concentration was fixed at 20 g R-sugar/L. The maximum hydrogen yield was 0.99 mol H 2/mol R-sugar at a substrate concentration of 15 g R-sugar/L. Using the Gompertz Equation Model simulation, the maximum hydrogen production rate was 253 mL H 2/h/L at a substrate of 30 g/L and initial pH of 8.4.

Heavy metal extraction from PCB wastewater treatment sludge by sulfuric acid

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

Evaluation and Characterization of Sorghum Biomass as Feedstock for Sugar Production

Conversion of cellulosic biomass, such as agricultural residues, to biofuels offers significant economic, environmental, and strategic benefits. Sorghum is an important energy crops in the U.S. It is a renewable resource and is currently grown on about 10 million acres in the U.S. However, at present, there is a lack of scientific information and knowledge about the use of sorghum biomass for biofuel production. The objective of this research was to evaluate and characterize sorghum biomass as a feedstock for sugar production. Five types of sorghum biomass (brown midrib sorghum, forage sorghum, grain sorghum, photoperiod-sensitive sorghum, and sweet sorghum) were characterized and evaluated for sugar production. Pretreatment with dilute acid was used to increase yield of fermentable sugars. Effects of sulfuric acid concentration, treatment temperature, and residence time on yield of fermentable sugars were studied. Accellerase 1000 was used to hydrolyze cellulose into glucose at 50C and pH 4.8 for 96 h. A high percentage of enzymatic conversion of cellulose (ECC) was observed for sorghum biomass that was pretreated under severe pretreatment temperature (85% to 98% ECC for biomass pretreated at 165C for 10 min; 65% to 82% ECC for biomass pretreated at 140C for 30 min). However, mass recovery and cellulose recovery of the solid fraction after pretreatment decreased under severe pretreatment conditions (70% to 85% cellulose recovery for sorghum biomass pretreated at 140C for 30 min; 31% to 58% cellulose recovery for sorghum biomass pretreated at 165C for 10 min).

Acid hydrolysis of corn stover for biohydrogen production using Thermoanaerobacterium thermosaccharolyticum W16

Abstract Lignocellulosic biomass, if properly hydrolyzed, can be an ideal feedstock for fermentative hydrogen production. This work considered the pretreatment of corn stover (CS) using a dilute acid hydrolysis process and studied its fermentability for hydrogen production by the strain Thermoanaerobacterium thermosaccharolyticum W16. The effects of sulfuric acid concentration and reaction time in the hydrolysis stage of the process were determined based on a 22 central composite experimental design with respect to maximum hydrogen productivity. The optimal hydrolysis conditions to yield the maximum quantity of hydrogen by W16 were 1.69% sulfuric acid and 117 min reaction time. At these conditions, the hydrogen yield was shown to be 3305 ml H2 L−1 medium, which corresponds to 2.24 mol H2 mol−1 sugar. The present results indicate the potential of using T. thermosaccharolyticum W16 for high-yield conversion of CS hemicellulose into bio-H2 integrated with acid hydrolysis.

Effect of Sulfuric Acid Concentration on Chalcopyrite Concentrate Chemical Leaching

This study reports the effect of sulfuric acid concentration on chalcopyrite chemical leaching in very simple H2SO4 solution systems ranging from 23g/L to 30g/L, with 2.5% chalcopyrite concentrate at 30°C. Copper extraction from chalcopyrite increases with an increase in sulfuric acid concentration, e.g. 86%, 90% and 92% after 96 days at 23g/L, 25/L and 27g/L H2SO4 solution respectively. Sulfur element formed on the surface of chalcopyrite was very porous as the result of an electron probe microanalyzer (EPMA). Copper extraction, however, leveled out at 35% after 20 days when the sulfuric acid concentration was higher than 28g/L on 25g/L of chalcopyrite concentrate. Sulfur element was detected by X-ray analysis as only a leaching reaction product. The passivation may be caused by thick elemental surface formed on the surface of chalcopyrite.

Leaching and recycling of zinc from liquid waste sediments

The selective leaching and recovery of zinc in a zinciferous sediment from a synthetic wastewater treatment was investigated. The main composition of the sediment includes 6% zinc and other metal elements such as Ca, Fe, Cu, Mg. The effects of sulfuric acid concentration, temperature, leaching time and the liquid-to-solid ratio on the leaching rate of zinc were studied by single factor and orthogonal experiments. The maximum difference of leaching rate between zinc and iron, 89.85%, was obtained by leaching under 170 g/L H 2SO 4 in liquid-to-solid ratio 4.2 mL/g at 65 °C for 1 h, and the leaching rates of zinc and iron were 91.20% and 1.35%, respectively.

Preparation of porous rutile titania from ilmenite by mechanical activation and subsequent sulfuric acid leaching

Synthesis of porous titania via mechanical activation of natural ilmenite and subsequent simultaneous dissolution and hydrolysis in dilute solutions of sulfuric acid was investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N 2 adsorption/desorption measurements, energy-dispersive X-ray spectrometry (EDX) and thermogravimetric analysis (TG). This is a novel template-free approach for synthesis of microporous, mesoporous and micro–mesoporous TiO 2 materials. Effects of sulfuric acid concentration and calcination temperature on physicochemical properties of the TiO 2 materials were examined systematically. The results show that both the factors considerably affected the porosity of the materials. In a 15% acid solution a microporous TiO 2 hydrolysate with BET surface area 109.3 m 2/g was prepared. With a 10% H 2SO 4, we obtained a more pure micro/mesopore TiO 2 hydrolysate with BET area of 257.6 m 2/g. Calcining the hydrolysate at ⩾500 °C led to the formation of a mesopore TiO 2. The mesoporous TiO 2 generated at 600 °C still has a BET area of 92.1 m 2/g. The high thermal stability is probably related to the presence of H 2SO 4 in the channel walls of hydrolysate. The XRD analysis indicated all the TiO 2 materials prepared in this study being rutile. The mechanism for formation of the porous rutile TiO 2 is mainly via in situ hydrolysis and precipitation of the dissolved titanium on the un-reacted ilmenite surface, where H 2SO 4 may play a very important role.

Effect of Electrolyte Acidity on Copper Plating Process Performance

The effect of sulfuric acid concentration in copper electroplating has been evaluated for semiconductor interconnect fabrication. Gapfill rates and defect densities were determined for 10, 80, and 175 g/l sulfuric acid concentration. The results show an increase in bottom growth rate with increased acidity in addition to a shape change in the film growth front. Chonopotentiometry was used to study the effect of acidity on organic additive responses in these electrolytes. Opposed to low acid chemistry, the suppressor becomes mass transport limited at higher acidity, suggesting concentration gradients could be related to the gapfill differences observed. Defect densities for low acid chemistry were found somewhat higher than for high acid electrolyte. This could be caused by differences in wetting behavior between chemistries.

Palladized aluminum as a novel substrate for electrosynthesis of polyaniline in sulfuric acid solutions

The electropolymerization of aniline on a palladized aluminum electrode (Pd/Al) by potentiodynamic as well as potentiostatic methods is described. The effect of the monomer concentration between 0.01 and 0.4 M on the polyaniline (PANI) formation and its growth on the Pd/Al electrode was investigated and a suitable concentration of 0.2 M is suggested. A similar study was carried out to investigate the effect of sulfuric acid concentration and 0.1 M sulfuric acid was chosen. A study on the influence of electropalladization time on the polymer formation and its growth suggested a convenient time of 40 s. The stability of the PANI film on the Pd/Al electrode was studied as function of the potential imposed on the electrode. For applied electrode potentials of 0.1–0.7 V, the first-order degradation rate constant, k, of PANI film varies between 1×10−6 and 2×10−5 s−1, and a relatively low slope (i.e., 2.2) was obtained for the plot of log k versus E. The coatings were characterized by scanning electron microscopy (SEM), and cyclic voltammetric behavior of the PANI-deposited Pd/Al electrode is discussed. The electrocatalytic activity of the PANI-deposited Pd/Al electrode against para-benzoquinone/hydroquinone (Q/H2Q) and % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX!% MathType!MTEF!2!1!+-% feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX% garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz% aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq% Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq% Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaada% WcgaqaaiaabAeacaqGLbWaaeWaaeaacaqGdbGaaeOtaaGaayjkaiaa% wMcaamaaDaaaleaacaaI2aaabaGaaG4maiabgkHiTaaaaOqaaiaabA% eacaqGLbWaaeWaaeaacaqGdbGaaeOtaaGaayjkaiaawMcaamaaDaaa% leaacaaI2aaabaGaaGinaiabgkHiTaaaaaaaaa!4681! $${{\text{Fe}}{\left( {{\text{CN}}} \right)}^{{3 - }}_{6} } \mathord{\left/ {\vphantom {{{\text{Fe}}{\left( {{\text{CN}}} \right)}^{{3 - }}_{6} } {{\text{Fe}}{\left( {{\text{CN}}} \right)}^{{4 - }}_{6} }}} \right. \kern-\nulldelimiterspace} {{\text{Fe}}{\left( {{\text{CN}}} \right)}^{{4 - }}_{6} }$$ redox systems were investigated and on the basis of % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX!% MathType!MTEF!2!1!+-% feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX% garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz% aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq% Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq% Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaacq% qHuoarcaWGfbWaaSbaaSqaaiaadchaaeqaaOGaeyypa0Jaamyramaa% DaaaleaacaWGWbaabaGaamyyaaaakiabgkHiTiaadweadaqhaaWcba% GaamiCaaqaaiaadogaaaaaaa!428E! $$\Delta E_{p} = E^{a}_{p} - E^{c}_{p} $$ of the corresponding cyclic voltammograms and the redox systems were identified as the reversible and quasi-reversible systems, respectively.

Effect of Sulfuric Acid Concentration on Acoustic Emission Signals in Uniform-Corrosion

In petroleum industry, corrosion failures of steel structures are common. The severity of corrosion in oil distillery inorganic compounds is higher than in those of organic compounds. Inorganic compounds such as sulfur are the most influential corrosive activators inside oil or chemical storage tanks. They normally have the tanks inspected and repaired along their life time. In addition the concentration of sulfur compound increases due to the accumulation of the residuals inside the tank, and so does the corrosive rate. In this paper, Acoustic Emission (AE) has been chosen to study the characteristic of AE signals received from the uniform corrosion mechanism of mild steel (A36) in various concentrations of Sulfuric acid (H2SO4) solution. AE signals were captured using a wide band sensor (WD) and recorded by AE system model LOCAN 320. The relationship between AE signals and sulfur concentrations as well as pH were exhibited.

Interaction between ozone and the chloride ion in sulfuric acid solutions up to 6-M concentration

The effect of sulfuric acid concentration on Cl2 evolution in the reaction between O3 and Cl− has been investigated. The catalytic effects of metal ions in this reaction have been studied as a function of solution acidity. The chlorine evolution rate increases markedly with increasing acid concentration. At acid concentrations below 4 mol/l, the most effective catalyst is Co2+. The catalytic activities of Fe3+ and Cu2+ peak at \(C_{H_2 SO_4 } \) = 4.8 mol/l. In passing to highly acidic solutions (\(C_{H_2 SO_4 } \) > 5 mol/l), the catalytic activity of the metal ions decreases, but the chlorine evolution rate remains high owing to the high acidity. Kinetics of VO2+ oxidation with ozone in acid media have been studied, and the ozone solubility in aqueous sulfuric acid has been measured.

Effect of sulfuric acid concentration on the structure of sulfate adlayer on Au(1 1 1) electrode

The adsorption of sulfate on Au(1 1 1) single-crystal electrode was examined in sulfuric acid solutions of various concentrations (0.5–7.5 M) by cyclic voltammetry and in situ scanning tunneling microscopy (STM). The well-known sulfate adlayer with (√3 × √7) unit cell was found in 0.5 M sulfuric acid by in situ STM. In 2.5 and 5.0 M sulfuric acid, a new order–disorder phase transition, from the (√3 × √7) adlayer to a disordered structure, was found to take place at ca. 1.1 V vs. Ag∣AgCl∣KCl(sat.). In 7.5 M sulfuric acid, no current spikes were seen in the CV profile, and in situ STM showed that the sulfate adlayer was disordered.

A Spectrophotometric Study of the Permanganate–Oxalate Reaction: An Analytical Laboratory Experiment

A spectrophotometric method has been developed to study the classic permanganate–oxalate oxidation–reduction reaction. The experiment is divided into two parts. Part I involves the determination of an unknown oxalate. This part of the experiment not only serves to quantitatively analyze oxalate by following and recording its slow bleaching effect on the absorbance of a measured excess of permanganate over a period of time, but also allows the student (i) to visually follow the course and the rate of the reaction, and (ii) to observe the auto catalytic effect of the reaction product, manganous ion. Part II of the experiment involves examination of the effect of sulfuric acid concentration and the effect of manganous ion concentration on the rate of and outcome of the permanganate–oxalate reaction. The experiment can be completed in two three-hour laboratory periods. The experiment can be modified by excluding Part II and thus be completed in one three-hour laboratory period. The experiment works well in the teaching laboratory and is well received by the students. The experiment intellectually stimulates and challenges the students. It provides the student with experience on the application of the major functions of modern recording UV–vis spectrophotometers and the basics of analytical techniques and stoichiometry calculations.

Vacancy ion-exclusion chromatography of aromatic carboxylic acids on a weakly acidic cation-exchange resin

Determination of aromatic carboxylic acids by conventional ion-exclusion chromatography is relatively difficult and methods generally rely on hydrophobic interaction between the solute and the resin. To overcome the difficulties in determining aromatic carboxylic acids a new approach is presented, termed vacancy ion-exclusion chromatography, which is based on use of the sample as mobile phase and an injection of aqueous 10% methanol onto a weakly acidic cation-exchange column (TSKgel OApak-A). Highly sensitive conductivity detection occurred with sharp and well-shaped peaks, leading to very efficient separations. The effects of sulfuric acid concentration added to the mobile phase, flow-rate, and column temperature on the retention volume of tested aromatic carboxylic acids was investigated. Retention times were found to be affected by the concentration of the analytes in the mobile phase and to some extent also by the addition of an organic modifier such as methanol to the injected water sample. Separation of sulfuric acid (SA), naphthalenetetracarboxylic acid (NTCA), phthalic acid (PA) and benzoic acid (BA) was satisfactory using this new approach. Detection limits were 0.66, 0.67, 0.42 and 0.86 μ M and detector responses were linear in the range 1–100, 1–80, 2.5–100 and 10–40 μ M, for SA, NTCA, PA and BA, respectively. Precision for retention times was 0.36% and for peak areas was 1.5%.

Sulfuric acid leaching of Turkish chromite concentrate

In this work a high grade chromite concentrate obtained from Pinarbasi–Kayseri district of Turkey was reacted with a solution of sulfuric acid and perchloric acid. The effect of sulfuric acid concentration, temperature, duration, and perchloric acid addition on leach recovery was studied. At the end of leach reaction chromium appeared in the solution as Cr 3+ and it did not change to environmentally hazardous Cr 6+. The final product in the solution was chromium(III) sulfate obtained with about 83% maximum recovery, under the optimum leaching conditions of 175 °C, 2 h, 70% H 2SO 4 and 1/2 perchloric acid/chromite ratio.

Dilute-acid hydrolysis of sugarcane bagasse at varying conditions.

Sugarcane bagasse, a byproduct of the cane sugar industry, is an abundant source of hemicellulose that could be hydrolyzed to yield a fermentation feedstock for the production of fuel ethanol and chemicals. The effects of sulfuric acid concentration, temperature, time, and dry matter concentration on hemicellulose hydrolysis were studied with a 20-L batch hydrolysis reactor using a statistical experimental design. Even at less severe conditions considerable amounts (>29%) of the hemicellulose fraction could be extracted. The percentage of soluble oligosaccharides becomes very low in experiments with high yields in monosaccharides, which indicates that the cellulose fraction is only slightly affected. For the sugar yields, acid concentration appears to be the most important parameter, while for the formation of sugar degradation products, temperature shows the highest impact. It could be demonstrated that the dry matter concentration in the reaction slurry has a negative effect on the xylose yield that can be compensated by higher concentrations of sulfuric acid owing to a positive interaction between acid concentration and dry matter contents.

Use of partial least-squares regression for multicomponent determinations based on kinetic spectrofluorimetric data. Simultaneous determination of canrenone and spironolactone in urine.

A new spectrofluorimetric method for the simultaneous determination of canrenone and spironolactone in urine is proposed. The method is based on the different rates at which the two analytes react with hot sulfuric acid to form a trienone. The kinetic spectrofluorimetric data are processed by partial least-squares regression. The effects of sulfuric acid concentration and temperature on the system under study were also evaluated and the optimum values for carring out the reaction were 50% and 50 degrees C, respectively. The method was checked by analyzing urine samples that they contained both diuretics. The accuracy and the precision of the method were tested. The relative standard errors in the quantification of each analyte in all tested samples were 3.69 and 3.59%. The proposed method was validated by comparison with a high performance liquid chromatographic method for urine samples.