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Effects of temperature and concentration of sulfuric acid on the electrodeposition of grainy electrolytic manganese dioxide

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Journal of University of Science and Technology Beijing 2005年第6期12卷 553-557页

作者： Huajun Guo Xinhai Li Luping Liu Xinming Zhang Zhixing Wang Wenjie Peng Bingquan Zhu College of Metallurgical Science and Engineering Central South University Changsha 410083 China

The effects of temperature and the concentration of sulfuric acid on the cell voltage, the anode current efficiency of electrodeposition and the particle size of grainy electrolytic manganese dioxide （EMD） were investigated. The structure, particle size and appearance of grainy EMD were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrograph measurements. As the concentration of sulfuric acid increases, both the cell voltage and the average anode current efficiency decrease. With the increase of electrolysis temperature in the range of 30-60℃, the cell voltage, average anode current efficiency and particle size decrease. The optimum temperature of 30℃ and concentration of sulfuric acid of 2.5 mol/L for electrodeposition of the grainy EMD were obtained. XRD patterns show that the grainy EMD electrodeposited under the optimum conditions consists of γ-MnO2 and has an orthorhombic lattice structure. According to the results of SEM, the grainy EMD has a spherical or sphere-like appearance and a narrow particle size distribution with an average size of about 7μm. The grainy EMD is a promising cathode of rechargeable alkaline batteries for high energy density and a prospective precursor for production of the LiMn2O4 cathode of lithium ion batteries.

关键词： alkaline batteries electrolytic manganese dioxide temperature sulfuric acid electrodeposition

Kinetics of nickel leaching from roasting-dissolving residue of spent catalyst with sulfuric acid

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Journal of Central South University 2009年第3期16卷 410-415页

作者：冯其明邵延海欧乐明张国范卢毅屏 School of Resources Processing and Bioengineering Central South University

sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and the leaching kinetics of nickel was analyzed. The experimental results indicate that the effects of particle size and sulfuric acid concentration on the nickel extraction are remarkable; the effect of reaction temperature is mild; while the effect of stirring speed in the range of 400-1 200 r/min is negligible. Decreasing particle size or increasing sulfuric acid concentration and reaction temperature, the nickel extraction efficiency is improved. 93.5% of nickel in residue is extracted under suitable leaching conditions, including particle size （0.074-0.100） mm, sulfuric acid concentration 30% （mass fraction）, temperature 80 ~C, reaction time 180 min, mass ratio of liquid to solid 10 and stirring speed 800 r/min. The leaching kinetics analyses shows that the reaction rate of leaching process is controlled by diffusion through the product layer, and the calculated activation energy of 15.8 kJ/mol is characteristic for a diffusion controlled process.

关键词： kinetics leaching nickel sulfuric acid spent catalyst

Leaching of vanadium from stone coal with sulfuric acid

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Rare Metals 2009年第1期28卷 1-4页

作者： WANG Mingyu XIAO Liansheng LI Qinggang WANG Xuewen XIANG Xiaoyan School of Metallurgical Science and Engineering Central South University Changsha 410083 China

The effects of roasting, mass ratio of H2SO4 to stone coal, leaching temperature, liquid-to-solid ratio, grinding fineness of stone coal, and two-stage counter-current leaching on the vanadium leaching ratio were studied. The results show that the vanadium leaching ratio of roasted stone coal through two-stage counter-current leaching can reach 65.1% at the mass ratio of H2SO4 to stone coal of 20%, leaching temperature of 95℃, leaching time of 30 h, liquid-to-solid ratio of 1.1 mL·g^-1, and grinding fineness of 0.1 mm, which can serve as an experimental basis for the production of vanadium from stone coal.

关键词： stone coal vanadium sulfuric acid leaching

The impacts of ambiguity in preparation of 80% sulfuric acid solution and shaking time control of calibration solution on the determination of transparent exopolymer particles

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Acta Oceanologica Sinica 2023年第4期42卷 50-58页

作者： Congcong Guo Guicheng Zhang Shan Jian Wei Ma Jun Sun Institute of Marine Science and Technology Shandong UniversityQingdao 266237China Institute for Advanced Marine Research China University of GeosciencesGuangzhou 511462China Research Centre for Indian Ocean Ecosystem Tianjin University of Science and TechnologyTianjin 300457China Huaihe River Basin Eco-environment Monitoring and Scientific Research Center Huaihe River Basin Eco-environment Supervision and Administration BureauBengbu 233001China

The quantification of transparent exopolymer particles(TEP) by colorimetric method is of large error and low repeatability,one major reason of which is related to the absence of clear definition and evaluation for part steps of the original *** is obscure that the 80% sulfuric acid solution,acted as the extraction solution in the determination of TEP,is prepared based on a volume ratio or mass ***,the change of solubility of recently available Gum Xanthan(GX) from the market means that the original protocol is no longer applicable,and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of *** found that different preparation techniques could result in the varied concentrations of 80% H_(2)SO_(4).The duration of shaking during the preparation of standard solution significantly affected the slope of the calibration curve,which caused different correction results of *** impacts of different extraction solution concentrations and shaking time of GX solution on the quantification of TEP were investigated based on the field sampling and laboratory *** extraction capacities of H_(2)SO_(4) with different concentrations for Alcian Blue were distinct,but had limited effect on the final measuring result of *** change of the standard curve slope came along with the variation of shaking time,which markedly altered the detection limit and calibration result,and the extended shaking time was in favor of the determination of low-concentration *** was suggested that the extraction solution concentration,shaking time and filtration volume of standard solution are required to be well controlled and selected to obtain more accurate results for TEP with different concentrations.

关键词： transparent exopolymer particles determination method method improvement sulfuric acid shaking time

Amelioration of Saline-Sodic Soils with Tillage Implements and sulfuric acid Application

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Pedosphere 2007年第2期17卷 182-190页

作者： M.SADIQ G.HASSAN S. M. MEHDI N. HUSSAIN M. JAMIL Soil Salinity Research Institute Pindi Bhattian Hafizabad District(Pakistan)

Amelioration of saline-sodic soils through land preparation with three tillage implements （disc plow, rotavator and cultivator） each followed by application of sulfuric acid at 20% of gypsum （CaSO4-2H2O） requirement or no sulfuric acid application during crop growth period was evaluated in a field study for 2.5 years at three sites, i.e., Jhottianwala, Gabrika （Thabal）, and Thatta Langar, in Tehsil Pindi Bhattian, Hafizahad District, Pakistan. Within 2.5 years, there was a decrease in the salinity parameters measured （electrical conductivity, pH, and sodium adsorption ratio）, with a gradual increase in rice and wheat grain yields. It was observed that the disc plow, which not only ensured favorable yields but also helped improve soil health at all the three sites, was the most effective tillage implement. Also, application of sulfuric acid resulted in higher yields and promoted rapid amelioration of the saline-sodic soils.

关键词： amelioration saline-sodic soils salinity parameters sulfuric acid tillage implements

Rock chemical weathering by sulfuric acid: pathway, method and prospect

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Acta Geochimica 2017年第3期36卷 474-478页

作者： Dong Zhang Zhiqi Zhao School of Resource and Environment Henan Polytechnic University State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences

To investigate the role of sulfuric acid-based carbonate weathering in global CO_2 sequestration of climate changes, we systematically discussed the pathway of sulfuric acid in rock chemical weathering and its feedback mechanism for global warming. We showed the methods used to determine the accurate amount of sulfate flux,accounting for the sulfuric acid resulted from sulfide oxidation. Finally, we pointed out some prospects for further detailed work on the exact calculation of the sulfate fluxes for the CO_2 net-release.

关键词： Chemical weathering sulfuric acid Global climate change Sulfate isotope

Mechanism explanation for SO_2 oxidation rate of Cs-Rb-V series sulfuric acid catalyst at low temperature

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中国有色金属学会会刊：英文版 2001年第3期11卷 462-465页

作者：陈振兴叶华刘今李洪桂 Cent S Univ Inst Chem & Chem Engn Changsha 410083 Peoples R China

The reaction kinetics of SO 2 oxidation on Cs Rb V series sulfuric acid catalyst promoted by alkali salts such as cesium and rubidium was studied. A three step reaction mechanism of SO 2 oxidation was proposed, in which it was assumed that oxidation of quadrivalent vanadium complex was a controlling step. Then, a mechanism model equation was concluded according to the three step reaction mechanism. The SO 2 oxidation rate was measured with a non gradient reactor under the conditions of temperature of 380～520?℃ and space velocity of 3?600～7?200?h -1 . Through calculating with Powell nonlinear regression method, the parameters of model equation were obtained: K 1=0.152?exp(-62?073/ (RT) ), K 2=8.18?exp(-2?384/ (RT) ), K 3=0.221?exp(-18?949/ (RT) ). It was found that the model equation could fit with all the experimental reaction rate data very well. [

关键词： reaction mechanism low temperature catalyst sulfur dioxide sulfuric acid

SEQUENTIAL OSCILLATIONS IN BrO_3^-—GALLIC acid—sulfuric acid—[Ni(TIM)]^(2+)SYSTEM

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Chinese Chemical Letters 1993年第6期4卷 523-526页

作者： Xiang Da ZHAO Zhi Qiang XU Shi Sheng NI Department of Chemistry,Anhui University,Hefei 230039

[Ni(TIM)]^(2+)can act as a catalyst in bromate—gallic acid—sulfuric acid system to produce sequential oscillations have been *** bromate solution is added to the reaction mixture,two sets of concen- tration oscillat... 详细信息

关键词： TIM SYSTEM SEQUENTIAL OSCILLATIONS IN BrO3 sulfuric acid Ni

Passive behavior of gold in sulfuric acid medium

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Transactions of Nonferrous Metals Society of China 2015年第6期25卷 2037-2046页

作者：张伟 Ahmet Deniz BAS Edward GHALI Yeonuk CHOI Department of Mining Metallurgical and Materials EngineeringLaval University Barrick Gold Corporation

Anodic behavior of pure Au as compared to platinum （Pt） in H2SO4 solutions was considered by different electrochemical techniques for an appropriate insight. Cyclic voltammetry studies showed two oxidation and one film reduction peaks for Au, while one oxygen evolution reaction for Pt. Increasing H2804 concentration （from 0.5 to 1 mol/L） caused 2-fold increases in peak current density of Au. Increase in agitation promoted passive zone of Au, while it was negligible for Pt by potentiodynamic studies. Potentiostatic studies （2 h） at three anodic passive potentials in 1 mol/L H2SO4 showed that the admittance of Au was found to be the lowest at 1.4 V. Electrochemical noise measurements during the decay periods （16 h） after polarization showed that the thin passive film formed during potentiostatic polarization has been dissolved.

关键词： gold passivation sulfuric acid electrochemical noise