Sulfuric Acid Of Various Concentrations Research Articles

Pengaruh Perlakuan Awal terhadap Karakteristik Bioetanol dari Limbah Kulit Singkong Karet (Manihot glaziovii)

Rubber cassava peel waste (Manihot glaziovii) has a high carbohydrate content, so it is feasible to convert it into bioethanol. In general, bioethanol production consists of four steps, pretreatment, hydrolysis, fermentation, and purification. The purpose of this study was to determine the suitable treatment for obtaining bioethanol with the finest characteristics from rubber cassava peel using three treatment variations, the pretreatment process with variations in the dissolving ratio of sodium hydroxide (NaOH) 0.5 M of 1:10; 1:12.5; and 1:15 (w/v), the hydrolysis process with various concentrations of sulfuric acid (H2SO4) of 0.15 N; 0.30 N; and 0.45 N, and the fermentation process with variations in the fermentation time for 3 days, 7 days, and 9 days. Based on the research results, the highest glucose content was 0.91%, with variations in dissolving NaOH 0.5 M 1:15 (w/v) in the pretreatment process and variations in the concentration of 0.30 N H2SO4 in the hydrolysis process, while the highest ethanol content was 68.05% at a fermentation time of 7 days.

Effects of ultrasound-assisted sulfuric acid treatment on the decontamination of Co nuclides in cement paste simulating radioactive concrete waste from dismantled nuclear power plants

This study proposes an ultrasonic treatment method for enhancing the decontamination efficiency of cement waste under the lower acid concentration. The phase transitions and decontamination efficiency of the hydrates and Co nuclides in the cement paste were respectively studied using various concentrations of sulfuric acid. The effect of pre-heating the acid-treated cement paste at 500 ℃ on its phase transition and decontamination efficiency were also studied. The underlying mechanism of the enhanced decontamination efficiency was elucidated by inductively coupled plasma spectrometry, powder X-ray diffraction, thermogravimetry, laser diffractometry, and X-ray absorption spectroscopy. Ultrasound-assisted decontamination by 1.0 M H2SO4 was 1.5 times more efficient than non-sonication-assisted decontamination with double the acid concentration (2.0 M H2SO4), owing to the detachment of the outer-layer phases of CaSO4 that obstructed the contact between the acid and the nuclides. The thermally-treated samples showed similar decontamination efficiencies under treatment with high acid concentrations and ultrasonication, due to the vigorous acid reaction kinetics regardless of the thermal decomposition of the hydrates.

Vanadium (II) Sulfate for the Reductive Leaching of Chalcopyrite: Replacing Smelting with Electrolysis for Copper Production

AbstractThe demand for copper is expected to outpace supply in the coming decades due in part to the emergence of wind and solar technologies, which require about five times as much copper as traditional energy sources. This work introduces a potentially transformative hydrometallurgical process to extract copper from chalcopyrite, and thereby sustain a high rate of copper production throughout the 21st century. Chalcopyrite is reacted with vanadium (II) sulfate for the first time to enable the rapid, clean, and complete recovery of copper. Reactions between 39 g/L copper concentrate, 1 M vanadium (II) sulfate, and various concentrations of sulfuric acid yielded a final product of solid copper sulfate, which was characterized by X‐ray diffraction (XRD) and scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDS) analysis. The solid products were leached in a subsequent step to demonstrate copper yields ranging from 95–99 %. The vanadium (II) ion may be regenerated by an electrolysis unit that leverages advances in vanadium flow battery technologies.

Batch and Packed Bed Column Studies of Azo Dyes Adsorption from the Aqueous Solutions Using Activated Sugarcane Bagasse Charcoal Adsorbent: Isotherm and Kinetic Studies

<p>Biosorption of azo dyes (RO-16, RB-120 & RB-19) from the aqueous solutions was investigated using the activated sugarcane bagasse charcoal adsorbent. The characteristics of the prepared adsorbent were analyzed by SEM, EDX, FTIR, XRD, TG & DT analysis, and the BET surface area of the sugarcane bagasse adsorbent was examined by N2 adsorption and desorption techniques. Batch adsorption studies were performed to determine the optimum pH, azo dye concentration, sugarcane dose & temperature, and both Langmuir & Freundlich isotherm studies fit well with the adsorption process. Packed bed column adsorption studies confirmed the earlier breakthrough of the adsorption process, and the column adsorption studies fitted with Thomas, Yoon-Nelson, BDST and Adams-Bohart models. The desorption studies were conducted by adding various concentrations of sulfuric acid, and regeneration of spent azo dyes was done by different cycles.</p>

КИНЕТИКА И МЕХАНИЗМ ПЕРЕГРУППИРОВКИ КУРЦИУСА м-НИТРОБЕНЗОИЛАЗИДА В ВОДНЫХ РАСТВОРАХ СЕРНОЙ КИСЛОТЫ

The kinetics and mechanism of the Curtius rearrangement of m-nitrobenzoyl azide in aqueous solutions of sulfuric acid of various concentrations has been studied. An increase of the acidity of the reaction solution an increase in the acidity of the reaction solution leads to an acceleration of the rearrangement. The rate-limiting step of the reaction is the rearrangement of the protonated form of m-nitrobenzoyl azide to the corresponding isocyanate

Impact of Acidity Profile on Nascent Polyaniline in the Modified Rapid Mixing Process-Material Electrical Conductivity and Morphological Study.

Polyaniline (PANI) was synthesized chemically with the modified rapid mixing protocol in the presence of sulfuric acid of various concentrations. A two-step synthetic procedure was utilized maintaining low-temperature conditions. Application of the modified rapid mixing protocol allowed obtaining a material with local ordering. A higher concentration of acid allowed obtaining a higher yield of the reaction. Structural characterization performed with Fourier-transform infrared (FTIR) analysis showed the vibration bands characteristic of the formation of the emeraldine salt in both products. Ultraviolet–visible light (UV–Vis) spectroscopy was used for the polaronic band and the p–p* band determination. The absorption result served to estimate the average oxidation level of PANI by comparison of the ratio of the absorbance of the polaronic band to that of the π–π* transition. The absorbance ratio index was higher for PANI synthesized in a more acidic solution, which showed a higher doping level for this polymer. For final powder products, particle size distributions were also estimated, proving that PANI (5.0 M) is characterized by a larger number of small particles; however, these particles can more easily agglomerate and form larger structures. The X-ray diffraction (XRD) patterns revealed an equilibrium between the amorphous and semicrystalline phase in the doped PANI. A higher electrical conductivity value was measured for polymer synthesized in a higher acid concentration. The time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis showed that the molecular composition of the polymers was the same; hence, the difference in properties was a result of local ordering.

Nucleophilic Substitution and Racemization of 3-Ethoxy-N-desmethyl-diazepam Enantiomers in Acidic Ethanol

pKal values of 3-ethoxy-N-desmethyldiazepam (3-EtO-NDZ) in ethanol and acetonitrile containing various concentrations of sulfuric acid,determined by spectrophotometry and spectropolarimetry, were found to be 3.4 and 0.63 respectively. Temperature dependent racemization of enantiomeric 3-EtO-NDZ in ethanol containing various acid concentrations was studied by monitoring changes of ellipticity at 365nm as a function of time on a spectropolarimeter. The racemization reactions were found to follow apparent first order kinetics. Thermodynamic parameters of the racemization reaction were: Eact = 16.7k cal/mol,and at 25℃:  ΔH≠ = 16.1 kcal/ mol, ΔS≠ = -22.0 cal/K/mol, and ΔG≠ = 22.6 kcal/mol, respectively. The racemization had an isotope effect (kH/kD) Of 1.9 at 42℃. Based on the results of this report and the results of literature reports on the preferred conformation of enantiomeric 3-substituted-1,4-benzodiazepines ,a nucleophilically solvated C3 carboniun ion intermediate resulting from either a P (plus) or a M (minus) conformation is proposed to be an intermediate. This intermediate is responsible for the stereoselective nucleophilic substitution and the subsequent racemization of 3-EtO-NDZ enantiomers in acidic ethanol.

Catalytic Performance of Sulfonated Carbon Catalysts for Hydrolysis of Palm Oil Empty Fruit Bunch

Utilizing lignocellulosic biomass into valuable products, such as chemicals and fuels, has attracted global interest. One of lignocellulosic biomass, palm oil empty fruit bunch (EFB), has major content of cellulose (30-40%), which is highly potential to be a raw material for fermentable sugar production. In this research, a series of sulfonated carbon catalysts with various concentrations of sulfuric acid (H2SO4, 10-30 v/v%) solutions have been successfully prepared and applied for a single stage of heterogeneous acid-catalyzed hydrolysis over microcrystalline cellulose and EFB under moderate temperature condition and ambient pressure. The catalysts’ physical and chemical properties were characterized by using a Thermogravimetric Analyzer (TGA), X-ray diffractometer, surface area analyzer, and Fourier-transform infrared spectrophotometer. The characterization results showed that sulfonated carbon had relatively similar physical properties with the parent of active carbon. The hydrolysis activity of sulfonated carbon catalysts gave various Total Reducing Sugar (TRS). The effects of sulfate loading amount in catalyst samples and various ionic liquids were investigated. The hydrolysis of pure microcrystalline cellulose powder (Avicel) using 30%-sulfonated carbon (30-SC) catalyst in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid at 150°C yielded the highest TRS of 16.11%. Subsequently, the catalyst of 30-SC was also tested for hydrolysis of EFB and produced the highest TRS of 40.76% in [BMIM]Cl ionic liquid at 150°C for 4 h. The obtained results highlight the potential of sulfonated carbon catalysts for hydrolysis of EFB into fermentable sugar as an intermediate product for ethanol production.

Characteristics and tribological behavior of the hard anodized 6061-T6 Al alloy

Abstract The hard anodizing process is one of the best choices to achieve high wear resistance in a 6061-Al alloy, which is commonly used in marine and aerospace applications. In this study, the hard anodizing process was performed by applying several current densities at different times. Two types of electrolytes containing various concentrations of sulfuric acid or oxalic acid were used as the bath. The microhardness of the coatings was measured. Morphology, thickness, and structure of the samples were investigated through a scanning electron microscope (SEM), and an X-ray diffractometer (XRD). Surface roughness and tribological behavior of the optimum samples were also examined. The results revealed that there was an optimum value for the electrolyte concentration, as well as the hard anodizing current density and time at which the hardest coating was obtained. All the oxide films had an amorphous structure. Doing the hard anodizing at 35 mA/cm2 in a sulfuric acid bath for 50 min resulted in a uniform and crack-free coating. The weight loss of this oxide film was 50 and 21 times lower than the substrate and the coating obtained in an oxalic acid bath at the optimum conditions, respectively.

Synthesis zeolite y from kaolin bangka belitung: activation of metakaolin with various concentration of sulfuric acid

Zeolite Y has been synthesized from Kaolin Bangka Belitung as precursor through activation of metakaolin with acid. The synthesis of zeolite Y consist of metakaolinitation, activation metakaolin with sulfuric acid using various concentrations (3, 6, 9, 12, and 15 M), aging, hydrothermal process for 24 hours at 100 °C. The solid products were characterized with X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The result of XRD and FTIR indicated that zeolite Y formed at the variations 3, 6, 9, 12, and 15M. Based on XRD pattern of the results, phase of zeolite P formed at the variation 3M. The surface morphology and ratio of Si/Al of Zeolite Y was analyzed using SEM-EDX. The SEM micrograph of zeolite Y and P with variation of sulfuric acid 3, 6, 9, 12, and 15M like octahedral and sphere form and the ratio of Si/Al of the products based on EDX are 1.7; 1.6; 1.58; 1.64; and 1.59 respectively.

Corrosion resistance of steel reinforcement in polymer silicate shyngizite concrete

Polymersilicate concrete is used for structures of industrial buildings in many industries, where production processes form an acidic wet- gas operating environment. The lightweight polymer silicate shungizite concrete, proposed by the author for external walls, can also be attributed to these materials. The polymersilicate composition is based on the components of schungite and schungizite. The composition also included liquid glass, sodium silicofluoride and furyl alcohol. These ingredients are usually adopted for polymersilicate concrete. Previously, the author carried out the research of physical and mechanical properties of the composition. The components based on schungite and schungizite were chosen because of their high acid resistance. The issue of the corrosion resistance of reinforcement in light polymer-silicate concrete has not been studied enough. This article presents the results of investigations of the corrosion resistance of steel reinforcement in polymer silicate shungizit concrete. The investigations were carried out in an airy environment of high humidity and in solutions of sulfuric acid of various concentrations. After the established time limits for corrosion testing, the corrosion of reinforcement in samples was not observed. Such a result was obtained due to the dense structure of the material and high acid resistance of the constituent components on the basis of schungite and shungizite. There is no need for additional protection of the concrete surface to prevent corrosion of the reinforcement in it . The author recommends the use of the material for reinforced structures of external walls exposed to an acidic wet- gas operating environment.

Preparation and characterization of cellulose acetate from cotton

The preparation and characterization of cellulose acetate from cotton was conducted in this study. Cotton was hydrolyzed using various concentrations of sulfuric acid (10, 20, 30 and 40%). The bleaching process was performed by using H2O2 solution. The acetylation process was conducted using acetic acid solution. The obtained cellulose acetate was then characterized using Fourier Transform Infrared Spectroscopy (FTIR) in order to observe the functional groups, Scanning Electron Microscopy (SEM) to examine the surface morphology and X-Ray Diffraction (XRD) to observe the crystallinity of cellulose acetate. The results of FTIR analysis confirmed the formation of cellulose acetate. SEM images showed the irregular sizes of cellulose acetate. XRD patterns exhibited that the acetylation process increased the crystallinity of cellulose.

Determination of quinine in soft drinks using the fluorometry method

The fluorimetric method of analysis has been proposed for the qualitative and quantitative determination of the food flavoring additive quinine in the tonic water. The fluorimetric method of analysis has high sensitivity, selectivity and express speed compared to the other methods. The optimal conditions for the quinine fluorimetric determination in the soft drinks were found: solvent - 0.01 M sulfuric acid, excitation wavelength of 353 nm, luminescence wavelength of 452 nm, strobe parameters - signal delay of 0.85 μs, signal duration of 21.25 μs. To increase the sensitivity of the developed method, quinine luminescence was studied in the various concentrations of sulfuric acid from 0.005 to 1.000 M, and the quantum yield of quinine luminescence in all the investigated concentrations of sulfuric acid was calculated. It has been established that the highest quinine luminescence intensity, the highest quantum yield, and the lowest solvent background signal were observed in 0.01 M H 2 SO 4 . The influence of the related compounds of the food matrix on the fluorimetric determination of quinine was studied. It has been established that the content of such components as sugar and citric acid in the soft drinks does not affect the luminescent signal of quinine. The detection limit of quinine was calculated, which amounted to 0.0019 mg/dm 3 . In order to verify the correctness of the fluorimetric method, the results were compared with the spectrophotometric method (maximum absorption of quinine at 347 nm). The results obtained by the two methods were in good agreement, and the detection limit of the fluorimetric method was higher compared to the known works. The proposed technique could be used to control the quality and safety of the soft drinks. Keywords : quinine, fluorimetry, tonic water, luminescence quantum yield, strobe parameters. DOI: http://dx.doi.org/10.15826/analitika.2019.23.3.007 (Russian) A.А. Nikolaeva, A.A. Ivanov, E.I. Korotkova National Research Tomsk Polytechnic University, Lenina prosp., 30 Tomsk, 634050, Russian Federation

Acidic hydrolysis performance and hydrolyzed lipid characterizations of wet Spirulina platensis

Acidic hydrolysis process of wet microalgae is a worthy technique to reduce the processes and energy of the production. To aim the alternative fuel as a biofuel feedstock from wet microalgae, the Spirulina platensis containing high moisture, 88–95 wt%, was representative in this research. Microalgae cell disruption by acidic hydrolysis was investigated using various concentrations of sulfuric acid with the hydrolysis temperature in the range of 25–100 °C and hydrolysis time in the range of 30–120 min. The acid-hydrolyzed lipid was extracted from the mixture by solvent extraction using n-hexane. The maximum lipid concentration from acidic hydrolysis was 17.15 wt% that obtained at hydrolysis temperature of 100 °C for 60 min and then extracted with 700 mL of hexane for 30 min. The physical and chemical analyses of the lipid and microalgae solid residue were examined. According to the research results, the higher heating values of hydrolyzed lipid were found in the range of 32–40 MJ/kg and their main chemical components were hexadecane, heptadecane, and palmitic acid. The boiling point ranges of the hydrolyzed lipid were mainly indicated in the fractions of light and heavy gas oils which may be generated in term of biofuel feedstock for automobile fuels.

Influence of growth parameters on the properties of TiO2 films prepared by anodic spark oxidation method and photocatalytic degradation of methylene blue

Porous titanium dioxide (TiO2) coatings were prepared on the pure titanium substrate by anodic spark oxidation (ASO) method in electrolytes containing various concentrations of sulfuric acid. The crystal phase, surface morphology, chemical composition, and optical property of the TiO2 films were analyzed by using XRD, SEM, XPS, and UV-vis spectroscopy. The photocatalytic activity is evaluated by the decomposition of methylene blue (MB) aqueous solution under UV light irradiation. It is found that the electrolyte concentration plays an important role in the properties and characteristics of the TiO2 coatings. The results show that TiO2 films consist of primarily the rutile phase with altering fraction depending on the electrolyte concentration without any heat treatment. The results demonstrated that there were formed too many sub-micron and nanopores of TiO2 neighboring to the micropores. TiO2 layer anodized in 0.75 M H2SO4 exhibited much higher photocatalytic activity than the other films. The results imply that anatase-rutile mixed TiO2 coatings can be successfully used for the photocatalytic degradation of organic pollutants.

Zinc Ion Removal on Hybrid Pectin-Based Beads Containing Modified Poly(Methyl Methacrylate) Waste.

A new hybrid sorbent in the form of round beads containing modified poly(methyl methacrylate) (PMMA) waste immobilized in pectin and crosslinked with calcium ions was prepared. A previously obtained and characterized powdered poly(methyl methacrylate)–based sorbent was used. Batch and column studies on the new material’s sorption-desorption properties were performed. Two kinetic models (pseudo-first- and pseudo-second-order) and three isotherms (Langmuir, Langmuir bisite and Freundlich) were used to describe the results. Breakthrough and elution curves were also obtained. Nitric, hydrochloric, and sulfuric acid of various concentrations were used in the desorption studies. Higher sorption affinity of zinc(II) ions to hybrid sorbent than to pectin alone, reflected by higher values of the Langmuir and Freundlich model parameters, was observed. The maximum sorption capacities, calculated based on the best-fitted models, were 50.2 mg/g (Langmuir bisite) and 42.2 mg/g (Langmuir) for hybrid and only pectin beads, respectively. The stripping of Zn ions using 0.1 M solutions of mineral acids was similarly effective in the case of both sorbents. The mass balance calculated for the column studies showed about 100% recovery of zinc in a sorption-desorption cycle. By applying the hybrid sorbent under the studied conditions it is possible to purify Zn in water to the level permitted by law and concentrate Zn(II) ions by about 60 times.

Thermodynamic complexity of sulfated zirconia catalysts

A series of sulfated zirconia (SZ) catalysts were synthesized by immersion of amorphous zirconium hydroxide in sulfuric acid of various concentrations (1–5N). These samples were fully characterized by X-ray diffraction (XRD), thermogravimetric analysis and mass spectrometry (TGA-MS), and aqueous sulfuric acid immersion and high temperature oxide melt solution calorimetry. We investigated the enthalpies of the complex interactions between sulfur species and the zirconia surface (ΔHSZ) for the sulfated zirconia precursor (SZP), ranging from −109.46±7.33 (1N) to −42.50±0.89 (4N) kJ/mol S. ΔHSZ appears to be a roughly exponential function of sulfuric acid concentration. On the other hand, the enthalpy of SZ formation (ΔHf), becomes more exothermic linearly as sulfur surface coverage increases, from −147.90±4.16 (2.14nm−2) to −317.03±4.20 (2.29nm−2) kJ/mol S, indicating formation of energetically more stable polysulfate ​species.

The effect of viscosity, applied frequency and driven pressure on the laser induced bubble luminescence in water–sulfuric acid mixtures

Production and oscillation of sonoluminescence bubbles by laser pulse in the presence of acoustic field in water and different concentrations of sulfuric acid are investigated. In the presence of acoustic field, the laser causes variable speed of sound, surface tension and density; and the host liquid acts as a compressible one and strongly affects the bubble's dynamics equations. The effect of various concentrations of sulfuric acid as a host liquid on the oscillation of bubble radius, bubble wall velocity and bubble interior temperature is studied. Furthermore, the effect of applied frequency on LI-SCBL in the presence of the acoustic field is investigated and an optimum sound wave frequency for the bubble oscillation and bubble interior temperature in pure water and SA is introduced. Based on the modification of RP equation, by applying the optimum frequency, the results indicate that the maximum bubble radius for LI-SCBL in the presence of the acoustic field is increased up to 7×10−4 m as this article presents, which is more than 40% improvement. This amount results in interior temperature of more than three times, from almost 5000 K in the previous works to almost 16 000 K in the present report. This is very similar to the experimental measurements for bubble radius induced by laser. Furthermore, the effects of driving pressure amplitudes on the bubble radius, the bubble interior temperature and the bubble wall velocity in different host liquids and in optimum frequency are investigated.

Thermal decomposition analysis of 1,1-bis(tert-butylperoxy)cyclohexane with sulfuric acid contaminants

Owing to the thermally unstable 1,1-bis(tert-butylperoxy)cyclohexane (BTBPC) having two active O–O peroxide group, it is a thermal instability material. It is usually used as an initiator in radical polymerization. This study focused on the runaway reactions of BTBPC alone and mixed with various concentrations of sulfuric acid (H2SO4) (1.0, 2.0, 4.0, and 8.0 N). The essential thermal stability kinetic parameters, such as exothermic onset temperature (To), peak temperature (Tp), apparent activation energy (Ea), heat of decomposition (ΔHd), and rate constant (k), were evaluated by differential scanning calorimetry (DSC) at the heating rate of 4.0 °C min−1 between 30.0 and 300.0 °C. A kinetics-based curve fitting method was employed to assess the thermal stability kinetic parameters and possible reaction scheme. H2SO4 appears to inhibit the decomposition reaction of BTBPC, especially when BTBPC is mixed with 8.0 N H2SO4.

Enhancement of photocatalytic reduction of CO2 to CH4 over TiO2 nanosheets by modifying with sulfuric acid

TiO2 nanosheets modified with various concentrations of sulfuric acid have been synthesized through hydrothermal treatment at 240°C followed by heat treatment at 105°C. Compared with untreated TiO2 nanosheets, the H2SO4-modified samples exhibited markedly improved quantum yield (QY), energy returned on energy invested (EROEI), and turnover number (TON) for CO2 reduction to CH4 under visible-light irradiation. As supported by physical-chemical characterization, the enhanced photocatalytic activities can be attributed to acidification promoting the formation of hydroxyl groups (Brønsted acidic sites) and oxygen vacancies/Ti3+ species. Thus, efficient charge separation and transfer to the TiO2 surface for both CO2 reduction and the accompanying H2O oxidation is facilitated. The highest activity for CO2 photoreduction to CH4 was obtained with TiO2 nanosheets with 0.5molL−1 H2SO4, with QY, EROEI, and TON of 0.726‰, 0.335‰, and 83.124, respectively. Furthermore, the catalyst maintained stable performance throughout five successive recyclability test runs.