Influence Of Sulfuric Acid Concentration Research Articles

Analysis of Reaction Rate and Product Selectivity of Ethanol Electrolytic Oxidation Reaction in the Flow Reactor

Introduction In recent years, the development of the electrolysis hydrogen production process has been vigorously promoted due to the widespread use of hydrogen energy. However, oxygen, a byproduct of the anode reaction, has not been utilized. On the other hand, chemical products are produced industrially by electro-organic synthesis, and if the anode reaction could be used directly as a chemical synthesis reaction, the overall benefit would be further enhanced. At the same time, the high selectivity and controllability of the electrochemical process make it possible to produce highly selective chemical products by anodic reactions. The objective of this study is to develop a process for simultaneous electrolytic hydrogen production at the cathode and highly selective acetaldehyde production at the anode. Experimental A schematic diagram of the experimental setup is shown in Figs. 1 and 2. Platinum electrodes were placed on silicone gaskets with flow channels, and the gaskets were sandwiched between silicone gaskets, PTFE plates, and stainless-steel endplates. A cation exchange membrane NR-212 was placed in the center to separate the reactions at the two electrodes. A 0 to 0.5 mol/L sulfuric acid solution containing 0.01 to 1.0 mol/L ethanol or a 0 to 0.5 mol/L sulfuric acid solution containing 0.01 to 1.0 mol/L acetaldehyde was supplied to the anode, and a 0 to 0.5 mol/L sulfuric acid solution was supplied to the cathode. Results and Discussion The experimental results are analyzed based on the premise of surface reaction rate limitation and steady-state conditions. As shown in Fig. 3, the ethanol conversion increased with rise in A/v (ratio of electrode area to flow rate), reaching its maximum value at A/v of 88.4 min/cm. This can be attributed to the difficulty in discharging bubbles generated from the electro-oxidation reaction as the A/v was raised. To ensure that the reactions occurred under reaction rate-limiting conditions, acetaldehyde electro-oxidation experiments were conducted with feed concentrations of 0 to 0.5 M sulfuric acid solutions containing 1.0 M acetaldehyde at the anode, and 0 to 0.5 M sulfuric acid solutions at the cathode, an A/v of 88.4 min/cm, and a potential difference of 1.0 V. The reaction rate was also affected by the reduction in the hydroxide ion concentration due to the increased sulfuric acid concentration, leading to the lower measured reaction rates. In the result of Fig. 4, it can be inferred that when the concentration of sulfuric acid was below 0.1 M, the reaction rate was governed by diffusion. Subsequently, acetaldehyde electro-oxidation experiments were performed under acetaldehyde concentrations ranging from 0.01 to 1 M, a sulfuric acid concentration of 0.1 M, the fixed A/v, and potential differences between 0.8 and 1.2 V to elucidate the impact of reactant concentration on the reaction rate. The results in Fig. 5 demonstrate that while the reaction rates increased with raising the acetaldehyde concentration, it eventually approached a plateau, attributable to the saturation of active sites with acetaldehyde on the Pt electrode.The results of ethanol electro-oxidation experiments were shown in Figs. 6 and 7, decrease in acetaldehyde selectivity was observed with a feed concentration of a 0.1 M sulfuric acid solution, attributable to the formation of acetic acid and carbon dioxide as byproducts. Subsequently, in comparison to sulfuric acid concentrations below 0.2 M, under the conditions of 0.5 M sulfuric acid concentration and low conversion, the acetaldehyde selectivity exhibited a gradual decline as the conversion increased. This indicates that the influence of sulfuric acid concentration on the oxidation reaction of acetaldehyde to acetic acid was more significant than that on the oxidation reaction of ethanol to acetaldehyde. A plausible explanation for this phenomenon is that the oxidation of acetaldehyde is considerably inhibited by the adsorption of sulfate ions to the active sites, as it is associated with a second-order reaction of adsorbed species concentration. Consequently, altering the sulfuric acid concentration results in changes in the ethanol electro-oxidation reaction selectivity. Conclusions The selectivity of ethanol electro-oxidation reaction was significantly influenced by potential difference and electrolyte concentration. Notably, acetic acid was not produced at potential differences below 0.8 V. Sulfuric acid concentration affected reaction selectivity, with a greater impact on acetaldehyde-to-acetic-acid oxidation. Despite the higher selectivity observed at 0.6 V, the reaction rate was low. Employing an appropriate potential difference and electrolyte concentration can facilitate achievement both of higher selectivity and an enhanced reaction rate. Optimal conversion was achieved at an A/v of 88.4 min/cm, while the maximum acetaldehyde selectivity of approximately 95 % was observed at an applied voltage of 1.2 V and 0.5 M sulfuric acid concentration. Figure 1

Corrosion Study on Ni-based Alloy in Acidic Environment

Ni-based alloys have excellent corrosion resistance and are widely used in the petrochemical industry. In this study, the effects of sulfuric acid concentration on the corrosion resistance of Ni-based alloys were analyzed by software simulation and electrochemical tests. The results show that the corrosion rate of the alloy is gradually increased with the increase of sulfuric acid concentration, and the influence of sulfuric acid concentration on the corrosion rate of 304 stainless steel is greater than that of nickel-based alloy. In a 10% sulfuric acid solution, the corrosion rate of the four nickel-base alloy samples is only one-twentieth of that of the 304 stainless steel substrate.

Production of Glucose from Waste Bark Acacia Mangium Using Delifnification and Chemical Hydrolysis Process

The bark of Acacia mangium is lignocellulosic biomass from waste pulp which can be recovered by means of hydrolyse to produce simple sugar called glucose. To produce glucose, there are two stages of the process performed is process using solvent delignification NaOH and KOH. The parameters analyzed were the biomass with a solvent ratio (1:6, 1:8, 1:10, 1:12). The second stage cellulose is then hydrolyzed to see the influence of sulfuric acid concentration of the resulting glucose content (0.1; 0.25; 0.40; 0.55% (v/v)).Lignin removal efficiency using NaOH and KOH solvent that is almost equal to 62.39%. Decrease hemicellulose using KOH solvent (36%) are more efficient than solvent only 29.3% NaOH. Efficiency increased levels of cellulose using NaOH or KOH solvent almost equal approximately 85.5%, but with KOH the lower alkaline properties provide a more stable rise. Solvent delignification process with NaOH provide large enough glucose content at a ratio of 1: 6 and 1: 8 with sulfuric acid concentration in the range of 0.1 to 0.4 and 0.5% v/v. Increased glucose content in the solvent of NaOH at a ratio of 1:6 reached 69.88 ppm for sulfuric acid concentration of 0.55% v/v, whereas the content of glucose degradation products of cellulose with delignification process using KOH solvent is in the range of 3.25 ppm to 77.67 ppm. The highest value is produced by the hydrolysis of cellulose to the sulfuric acid concentration of 0.4% v/v, and the KOH solvent ratio is 1:10. The higher the ratio, the lower the KOH solvent content of glucose produced.

Influence of sulfuric acid concentration in the simultaneous voltammetric determination of uranium and plutonium in nuclear fuels.

Interfacial coupled chemical reaction between U(iv) (formed at the electrode surface) and Pu(iv) (diffuses from the bulk towards the electrode) regenerates U(vi) at the electrode-solution interface and causes enhancement in the U(vi) reduction current, thus creating problems in the simultaneous voltammetric determination of U and Pu. Despite such interference between U(iv) and Pu(iv), the simultaneous voltammetric determination of U and Pu in FBTR Mark-1 fuel samples in sulfuric acid (1 M H2SO4) on a poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(styrenesulfonate) (PSS)-modified glassy-carbon (GC) electrode (PEDOT-PSS/GC) has been reported. However, the reported method is applicable only for FBTR mark-1 fuel samples, in which the ratio [Pu]/[U] > 2 is always maintained. For nuclear samples having [Pu]/[U] < 2 (e.g., PFBR fuel), the simultaneous voltammetric determination of U and Pu is extremely challenging. Herein, we report a modified version of the earlier method for the simultaneous determination of U and Pu in nuclear samples ((U, Pu)C and (U, Pu)O2), irrespective of the [Pu]/[U] ratio. The effect of acidity (H2SO4 conc.) on the coupled chemical reaction between U(iv) and Pu(iv) was examined. It was observed that an increase in the acidity of H2SO4 minimized the coupled chemical reaction, and at 5 M H2SO4, change in the Pu(iv) concentration did not have any effect on the U(vi) reduction current. The coupled chemical reaction between U(iv) and Pu(iv) ceased at 5 M H2SO4 and hence, the simultaneous voltammetric determination of U and Pu was possible on PEDOT-PSS/GC, irrespective of the [Pu]/[U] ratio in 5 M H2SO4. The method was applied for both (U, Pu)O2 (PFBR) and (U, Pu)C (FBTR) samples and was compared with the well-established biamperometric method. The present method shows accuracy and precision comparable to biamperometry and did not show any interference from the commonly encountered impurities in nuclear samples. Thus, both FBTR and PFBR nuclear fuels having different [Pu]/[U] ratios can be analyzed by the present approach and it is a strong competitor to replace the well-established biamperometric method for routine sample analysis.

Influence of sulfuric acid concentration on biohydrogen production from rice mill wastewater using pure and coculture of Enterobacter aerogenes and Citrobacter freundii

We report a concise study on the influence of sulfuric acid concentration used in the hydrolysis of rice mill wastewater on biohydrogen production using pure as well as co-culture of Enterobacter aerogenes and Citrobacter freundii. A higher total reducing sugar release of 14.2 g/L was obtained with 1.5% sulfuric acid (v/v). The effect of pH on cumulative biohydrogen production from 1.5% acid hydrolyzed rice mill wastewater was investigated using pure and coculture of Enterobacter aerogenes and Citrobacter ferundii. The fermentative hydrogen production using mixed culture showed a maximum hydrogen yield of 1.61 mol/mol sugar. In addition, about 70% reduction in chemical oxygen demand (COD) and higher volatile fatty acids (VFA) production were observed. Modified Logistic, Gompertz and Richards models were used to fit cumulative hydrogen production data whereas Logistic equation was used fit growth data. Richards model showed best fit and Logistic equation gave least error in predicting maximum hydrogen producing potential.

THE SPECTROPHOTOMETRIC DETERMINATION OF NITRITES WITH N,N-DIETHYLANILINE

A method for spectrophotometric determination of the total IO3− and IO4—ions was proposed. The method is based on the oxidation of N,N-diethylaniline in an excess of potassium bromide in the presence of sulfuric acid medium and on the measurement of the bromination product absorbance at 226 nm. The influence of sulfuric acid concentration on the sensitivity of the measurement has been determined and the optimum conditions have been established. The detection limits (blank + 3s) for iodate, periodate and their total content equal to 0.73; 0.69 and 0.61 mg∙L−1, respectively. The linearity range of the calibration graph was found to be 1.0−11.0 mg∙L−1 (sr ≤ 0,10, n = 5). The possibility of separate determination of iodate and periodate based on selective extraction IO4− silica modified with a quaternary ammonium salt is proposed. The metrological characteristics of the procedure were checked by means of the “entered-found” method on the control samples. The relative error did not exceed 0.10 for iodate and periodate determination on the control samples, and the relative error was not higher than ± 8.00 %. The effect of foreign ions on the iodate and periodate determination at 2.0∙10−5 mol∙L–1 has been studied. The proposed procedure is simple and suitable for iodate and periodate determination in various objects.

Microwave Assisted Acid Pretreatment of Oil Palm Empty Fruit Bunches (EFB) to Enhance Its Fermentable Sugar Production

The influence of sulfuric acid concentration in aqueous glycerol during microwave pretreatment on the chemical content and morphological characteristics changes of pretreated EFB were investigated. After pretreatment, the pulp was further subjected to enzymatic hydrolysis. The micro-morphology and crystallinity of original and pretreated EFB were observed by scanning electron microscopy (SEM) and X-ray diffraction. Lignin content of pretreated EFB was determined, while hydrolysate after enzymatic hydrolysis was also analyzed the reducing sugar content. These results indicated that microwave assisted acid pretreatment of EFB caused weight loss. Evaluation on effect of varying acid concentration and residence times results 1 % acid concentration for 12.5 min as the best pretreatment condition. Under the best pretreatment condition, lignin removal was about 59.16 % with the reducing sugar yield per original EFB was 25.09 or 55.85 % per pretreated EFB. The acid–glycerol catalyst successfully improved reducing sugar yield compared to both untreated and biological pretreated samples. SEM images revealed that the pretreated of EFB surface changed noticeably and the increase of crystallinity degree of pretreated EFB indicated a great effect on amorphous region to crystalline region. The addition glycerol in reaction mixture both acid and alkaline has synergistic effect to increase reducing sugar yield. Much volume of glycerol in mixture has great effect to improve enzymatic hydrolysis performance than that of acid ones. The highest reducing sugar yield is produced as much as 98 % when EFB irradiated using glycerol–acid ratio of 1:2 for 12.5 min at 1 % acid concentration. The addition glycerol of 2 fold can increase 3.9 fold reducing sugar yield in the best pretreatment condition. Microwave assisted acid pretreatment in aqueous glycerol was an effective way to increase reducing sugar yield of EFB by lignin removal and fiber disruption.

Eng

Red macroalgae have the potential to be processed into bioethanol due to their high carbohydrate and low lignin content. Gelidium latifolium and Gracilaria verrucosa are red macroalgae commonly found in Indonesian seas. Sometimes an over-supply of red macroalgae is rejected by the food industry, which opens up opportunities for others uses, e.g. for producing bioethanol. The objectives of this research were to analyze the influence of sulfuric acid concentration on hydrolysis of G. latifolium and G. verrucosa and to calculate the optimum fermentation process to produce bioethanol. G. latifolium and G. verrucosa were hydrolyzed using H 2 SO 4 at concentrations of 1%, 2%, 3%, and 4%, at a temperature of 121 °C and a pressure of 1.5 bar for 45 minutes. The process of fermentation was done using Saccharomyces cerevisiae in anaerobic conditions for 4, 5, 6 and 7 days. The results show that the optimum H2SO4 concentrations to hydrolyze G. latifolium and G. verrucosa were 1% and 2% respectively. The number of S. cerevisiae cells in hydrolysate G. latifolium and G. verrucosa increased in the third adaptation. S. cerevisiae can convert sugar from G. latifolium and G. verrucosa into bioethanol through fermentation. The highest bioethanol yields were achieved on days five and six. Therefore, red macroalgae can be seen as a potential raw material for bioethanol production.

Leaching of Heavy Metals from Municipal Solid Waste Incineration (MSWI) Fly Ash Using Sulfuric Acid

Municipal solid waste incineration (MSWI) fly ash, a must by-product in incineration of municipal solid waste (MSW) combustion is of environmental concern due to its enrichment in heavy metals (Ni, Cd, Cu and Pb). Extraction using sulfuric acid is a conventional method of safe treatment of fly ash. In this work, influence of sulfuric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that Removal ratio followed the decreasing sequence of Cd &gt; Cu &gt; Pb &gt;Zn for acid extraction using sulfuric acid, quite different with that sequence of Pb &gt; Cd &gt; Cu &gt; Zn for extraction using nitric acid. Sulfuric acid was efficient in removing Cd and Cu, but less efficient in removing Ni and Zn. Compared with nitric acid, sulfuric acid was less effective in removing Pb, Cu and Ni.

Effect of acid concentration and pulp properties on hydrolysis reactions of mercerized sisal

The influence of sulfuric acid concentration (H2SO4 5–25%, 100°C), crystallinity and fibers size on the hydrolysis reaction of sisal pulps were investigated, with the goal of evaluating both the liquor composition, as an important step in the production of bioethanol, and the residual non-hydrolyzed pulp, to determine its potential application as materials. Aliquots were withdrawn from the reaction media, and the liquor composition was analyzed by HPLC. The residual non-hydrolyzed pulps were characterized by SEM, their average molar mass and crystallinity index, and their size distribution was determined using a fiber analyzer. Sulfuric acid 25% led to the highest glucose content (approximately 10gL−1), and this acid concentration was chosen to evaluate the influence of both the fiber size and crystallinity of the starting pulp on hydrolysis. The results showed that fibers with higher length and lower crystallinity favored glucose production in approximately 12%, with respect to the highly crystalline shorter fibers.

Ultrasonication-assisted preparation of water-in-oil emulsions and application to the removal of cationic dyes from water by emulsion liquid membrane: Part 2. Permeation and stripping

The main objective of this work is the utilization of W/O emulsions prepared by low-frequency ultrasonic irradiation (22.5 kHz) for the removal and recovery of cationic dyes from aqueous solution by emulsion liquid membrane containing di(2-ethylhexyl) phosphoric acid (D2EHPA) as carrier. The important parameters governing the extraction behavior of dyes have been investigated. These parameters were contact time of the external phase with W/O emulsions, external phase concentration, feed phase pH, stirring speed, extractant concentration, presence of salts, and type of diluent. The extraction of a mixture of four cationic dyes (methylene blue, rhodamine B, malachite green, and basacryl red GL) is also investigated in the absence and presence of salt in the external phase. The possibility of stripping the dyes is evaluated and the influence of sulfuric acid concentration on the stripping efficiency is also examined. The obtained results show that, under most favorable conditions, practically all the dye cations present in the feed phase were extracted. The removal percentage of the mixed dye was found to be higher than 98% even in the presence of salt in the continuous phase. The transport mechanism of cationic dyes for the present system was determined and divided into six stages. The best sulfuric acid concentration in the internal phase that conducted to very good stripping efficiency (≥97%) and excellent emulsion stability was 0.5 M. In all cases, the recovery of the membrane phase was total and the extraction of dyes was not decreased up to seven runs.

Influence of H 2SO 4 concentration on the performance of lead-acid battery negative plates

The influence of sulfuric acid concentration on negative plate performance has been studied on 12 V/32 Ah lead-acid batteries with three negative and four positive plates per cell, i.e. the negative active material limits battery capacity. Initial capacity tests, including C20 capacity, cold cranking ability and Peukert tests, have been carried out in a wide range of sulfuric acid concentrations (from 1.18 to 1.33 sp.gr.). High initial capacity and good CCA performance were registered for batteries with acid concentration between 1.24 and 1.30 sp.gr. The charge acceptance depends on acid concentration as well as on battery state of charge. Batteries with high SoC exhibit high charge acceptance at low acid concentrations. The cycle life tests at two discharge rates (10 and 3 h discharge) evidence that sulfuric acid concentration exerts a strong effect on negative plate performance. The cycle life of batteries decreases with increase of acid concentration. The obtained results demonstrate the high impact of lead sulfate solubility on the cycle life and charge efficiency of lead-acid batteries.

Seed layer corrosion of Damascene structures in copper sulfate electrolytes

The influence of sulfuric acid concentration in copper sulfate plating solutions on the stability of a 1000 Å seed layer in Damascene structures is presented. Immersion of a seeded wafer into the plating solutions results in chemical dissolution, thinning the copper seed layer. Anodic current density steps initiate seed layer corrosion resulting in exposure of the underlying TaN barrier layer. Large applied current density steps (>300 μA/cm 2) or high free sulfuric acid concentration causes very rapid dissolution of the seed layer. The anodic dissolution efficiency is greater than 100% indicating that chemical dissolution of copper is contributing to the disappearance of the copper seed layer.

Influence of Sulfuric Acid Concentration on the Anodic Behavior of Silver during Potentiodynamic Polarization

INTRODUCTIONResearch into the anodic dissolution of silver understeady-state polarization in neutral and acidic solutionsrevealed that the process rate is limited by diffusionremoval of simple or complex silver ions into solution[1–5]. At sufficiently positive potentials, passivatingfilms form at silver surface. These have an increasednumber of macrodefects (porosity) [3].Under a linear potential sweep, the silver oxidationin halide [6–8] and chromate [9] solutions occurs withformation of salt films in the reaction: z Ag + Ag

Preparation of cyclized rubber from natural rubber latex

AbstractIn this paper a new method for the preparation of cyclized rubber from natural rubber latex is described. In this method, which follows logically from the new way of preparing rubber hydrochloride from natural rubber latex, latex stabilized with nonionic or cationic emulsifying agents is mixed with sulfuric acid. If a sufficient amount of sulfuric acid is added, cyclized rubber is formed after some heating. The influence of sulfuric acid concentration and the temperature on the rate of reaction have been investigated. Other cyclizing agents proved to be hydrogen fluoride and boron trifluoride. The advantage of the method described is that cyclized rubber can be obtained in the form of a latex.

Influence of Sulfuric Acid Concentration upon Reaction between Olefins and Benzene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of Sulfuric Acid Concentration upon Reaction between Olefins and BenzeneV. N. Ipatieff, B. B. Corson, and Herman PinesCite this: J. Am. Chem. Soc. 1936, 58, 6, 919–922Publication Date (Print):June 1, 1936Publication History Published online1 May 2002Published inissue 1 June 1936https://doi.org/10.1021/ja01297a021RIGHTS & PERMISSIONSArticle Views213Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (438 KB) Get e-Alerts Get e-Alerts