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Stability,acidity and interaction properties of [Bmim][SbF_6] coupled with concentrated sulfuric acid

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Science China Chemistry 2017年第9期60卷 1243-1249页

作者： Honghua Zhang Ruixia Liu Ruirui Zhang Feng Huo Zhiqiang Yang Bin He Suojiang Zhang Yanji Wang School of Chemical Engineering Hebei University of Technology Key Laboratory of Green Process and Engineering Beijing Key Laboratory of Ionic Liquids Clean ProcessState Key Laboratory of Multiphase Complex SystemsInstitute of Process EngineeringChinese Academy of Sciences

Ionic liquid coupled with strong acid systems presents considerable promise in some catalytic fields. In the present work, the multiple complex systems composed by 98 wt% concentrated sulfuric acid and [Bmim][SbF6] were investigated in the terms of stability, acidity and interaction properties. It was found that acidolysis of [Bmim][SbF6] occurred in the 98 wt% concentrated sulfuric acid accompanied by HF releasing and SbF6−degrading to [SbF6−y(HSO4)y]−. The species after acidolysis in the multiple complex systems were checked and confirmed by electrospray ionization mass spectrometry (ESI-MS), Fourier transform infrared spectroscopy (FT-IR),1H NMR and19F NMR. acidity increased slightly with less than 1 wt% [Bmim][SbF6] addition, while decreased with more proportion, which was determined based on the Hammett acidity functions H0, using13C NMR. The strong hydrogen bond S–O–HF of interaction among the multiple complex systems was confirmed by molecular dynamic simulation. © 2017, Science China Press and Springer-Verlag Berlin Heidelberg.

关键词： Electrodeposition Electrospray ionization Fourier transform infrared spectroscopy Hydrogen bonds Ionic liquids Mass spectrometry Molecular dynamics sulfuric acid

Densities and surface tensions of ionic liquids/sulfuric acid binary mixtures

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Chinese Journal of Chemical Engineering 2018年第7期26卷 1513-1521页

作者： Tao Zhang Jing Hu Shengwei Tang Multi-phase Mass Transfer and Reaction Engineering Lab School of Chemical Engineering Sichuan University

The densities and surface tensions of [Bmim][TFO]/H2SO4, [Hmim][TFO]/H2SO4 and [Omim][TFO]/H2SO4 binary mixtures were measured by pycnometer and Wilhelmy plate method respectively. The results show that densities and surface tensions of the mixtures decreased monotonously with increasing temperatures and increasing ionic liquid （IL） molar fraction. IL with longer alkyl side-chain length brings a lower density and a smaller surface tension to the ILs/H2SO4 binary mixtures. The densities and surface tensions of the mixtures are fitted well by Jouyban-Acree （JAM） model and LWW model respectively. Redlich-Kister （R-K）equation and modified Redlich-Kister （R-K） equation describe the excess molar volumes and excess surface tensions of the mixtures well respectively. Adding a small amount of ILs （XIL 〈 0.1 ） into sulfuric acid brings an obvious decrease to the density and the surface tension. The results imply that the densities and surface tensions of IL5/H2SO4 binary mixtures can be modulated by changing the IL dosage or tailoring the IL structure.

关键词： Ionic liquid sulfuric acid Density Surface tension Excess property

Leaching isomorphism rare earths from phosphorite ore by sulfuric acid and phosphoric acid

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Rare Metals 2017年第10期36卷 840-850页

作者： Hui-Xin Jin Fu-Zhong Wu Xiao-Hao Mao Mei-Long Wang Hong-Yan Xie College of Materials and Metallurgy Guizhou University Guiyang 550025 China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025 China

Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H2SO4 is not an effective acid for leaching isomorphism RE from phosphorite ore. The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum （PG） as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H3PO4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H3PO4 solution and then add H2SO4 to crystallize PG. The effect of corystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.

关键词： Phosphorite Isomorphism Rare earths Leaching sulfuric acid Phosphoric acid

Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

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Chinese Journal of Chemical Engineering 2020年第4期28卷 1162-1170页

作者： Hongyin Pang Ruifang Lu Tao Zhang Li Lü Yanxiao Chen Shengwei Tang State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization Panzhihua 617000China School of Chemical Engineering Sichuan UniversityChengdu 610065China

In order to concentrate the diluted sulfuric acid from the titanium dioxide(TiO2)production of sulphate process,a new concentration process was proposed by coupling chemical dehydration and multi-effect *** ferrous sulfate monohydrate(FeSO4·H2O),as the dehydrant,was added to the diluted sulfuric acid to form ferrous sulfate heptahydrate(FeSO4·7H2O)according to the H2SO4-FeSO4-H2O phase diagrams,which partially removes the *** process was named as Chemical Dehydration *** residual water was further removed by two-effect evaporation and finally 70 wt%sulfuric acid was *** FeSO4·H2O can be regenerated through drying and dehydration of FeSO4·*** results show that FeSO4·H2O is the most suitable dehydrant,the optimal reaction time of chemical dehydration process is 30 min,and low temperature is favorable for the dehydration reaction.45.17%of the entire removed water can be removed by chemical dehydration from the diluted sulfuric *** chemical dehydration process is also energy efficient with 24.76%saving compared with the direct evaporation ***,51.21%of the FeSO4 dissolved originally in the diluted sulfuric acid are precipitated out during the chemical dehydration,which greatly reduces the solid precipitation and effectively alleviates the scaling in the subsequent multi-effect evaporation process.

关键词： Chemical dehydration Multi-effect evaporation sulfuric acid Titanium

Mechanochemical leaching of chalcopyrite concentrate by sulfuric acid

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International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 380-388页

作者： Farhad Khorramshahi Mohammadabad Sina Hejazi Jalil Vahdati khaki Abolfazl Babakhani Materials and Metallurgical Engineering Department Faculty of Engineering Ferdowsi University of Mashhad Materials and Metallurgical Engineering Department Faculty of Engineering University of Tehran

This study aimed to introduce a new cost-effective methodology for increasing the leaching efficiency of chalcopyrite concentrates at ambient temperature and pressure. Mechanical activation was employed during the leaching（mechanochemical leaching） of chalcopyrite concentrates in a sulfuric acid medium at room temperature and atmospheric pressure. High energy ball milling process was used during the leaching to provide the mechanochemical leaching condition, and atomic absorption spectroscopy and cyclic voltammetry were used to determine the leaching behavior of chalcopyrite. Moreover, X-ray diffraction and scanning electron microscopy were used to characterize the chalcopyrite powder before and after leaching. The results demonstrated that mechanochemical leaching was effective; the extraction of copper increased significantly and continuously. Although the leaching efficiency of chalcopyrite was very low at ambient temperature, the percentages of copper dissolved in the presence of hydrogen peroxide（H2O2） and ferric sulfate（Fe2（SO4）3） after 20 h of mechanochemical leaching reached 28% and 33%, respectively. Given the efficiency of the developed method and the facts that it does not require the use of an autoclave and can be conducted at room temperature and atmospheric pressure, it represents an economical and easy-to-use method for the leaching industry.

关键词： chalcopyrite mechanical activation mechanochemical leaching sulfuric acid cyclic voltammetry

Effect of hydrolysis conditions on hydrous TiO_2 polymorphs precipitated from a titanyl sulfate and sulfuric acid solution

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International Journal of Minerals,Metallurgy and Materials 2012年第7期19卷 642-650页

作者： Hao Song Bin Liang Li Lu Pan Wu Chun Li Department of Metallurgical Engineering Sichuan University Chengdu 610065 China

The relationship between hydrolysis conditions and hydrous titania polymorphs obtained in a titanyl sulfate and sulfmic acid solu- tion was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution transmission electron micros- copy （HRTEM）. The results revealed that the feeding rate of the titanyl sulfate stock solution, the concentration of *** acid, and the seed dosage of mtile crystal could significantly affect the hydrolysis rate, thus influencing the titania crystal phase. Hydrous TiO2 in the form of rutile, anatase, or the mixture of both could be obtained in solutions of low titanium concentrations and 2.5wt% to 15wt% sulfuric acid at 100℃. When the hydrolysis rate of titanitma expressed by TiOa was more than or equal to 0.04 g/（***）, the hydrolysate was almost phase-pure anatase, while the main phase state was rutile when the hydrolysis rate was less than or equal to 0.01 g/（***）. With the hy- drolysis rate between 0.02 and 0.03 g/（***）, the hydrolysate contained almost equal magnitude ofrutile and anatase. It seems that although rutile phase is thermodynamically stable in very acidic solutions, anatase is a kinetically stable phase.

关键词： titanium dioxide titanyl sulfate sulfuric acid hydrolysis anatase rutile

Selective leaching of lithium from spent lithium-ion batteries using sulfuric acid and oxalic acid

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 688-696页

作者： Haijun Yu Dongxing Wang Shuai Rao Lijuan Duan Cairu Shao Xiaohui Tu Zhiyuan Ma Hongyang Cao Zhiqiang Liu Institute of Advanced Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China Institute of Resources Utilization and Rare Earth Development Guangdong Academy of SciencesGuangzhou 510650China State Key Laboratory of Separation and Comprehensive Utilization of Rare Metals Guangzhou 510650China Guangdong Province Key Laboratory of Rare Earth Development and Application Guangzhou 510650China

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the *** methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable *** this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic *** optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and *** study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.

关键词： selective leaching oxalic acid sulfuric acid spent lithium-ion batteries

Theoretical Studies on Mechanism and Rate Constant of Gas Phase Hydrolysis of Glyoxal Catalyzed by sulfuric acid

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Chinese Journal of Chemical Physics 2016年第3期29卷 335-343,I0001,I0002页

作者：黄明强蔡顺有廖颖敏赵卫雄胡长进王振亚张为俊闽南师范大学化学与环境学院漳州363000 福建省现代分离分析科学与技术重点实验室漳州363000 厦门大学嘉庚学院环境科学与工程系漳州363105 中国科学院安徽光学精密机械研究所大气物理化学实验室合肥230031

The gas phase hydration of glyoxal （HCOCHO） in the presence of sulfuric acid （H2SO4） were studied by the high-level quantum chemical calculations with M06-2X and CCSD（T） theoretical methods and the conventional transition state theory （CTST）. The mechanism and rate constant of the five different reaction paths are consid- ered corresponding to HCOCHO＋H2O, HCOCHO＋H2O… H2O, HCOCHO… H2O＋H2O, HCOCHO＋H2O… H2SO4 and HCOCHO… H2O＋H2SOa. Results show that H2SO4 has a strong catalytic ability, which can significantly reduce the energy barrier for the hydration reaction of glyoxal. The energy barrier of hydrolysis of glyoxal in gas phase is lowered to 7.08 kcal/mol from 37.15 kcal/mol relative to pre-reactive complexes at the CCSD（T）/6- 311＋＋G（3df, 3pd）//M06-2X/6-311＋＋G（3df, 3pd） level of theory. The rate constant of the H2SO4 catalyzed hydrolysis of glyoxal is 1.34×10-11 cm3/（molecule.s）, about 1013 higher than that involving catalysis by an equal number of water molecules, and is greater than the reaction rate of glyoxal reaction with OH radicals of 1.10×10-11 cm3/（molecule·s） at the room temperature, indicating that the gas phase hydrolysis of glyoxal of H2SO4 catalyst is feasible and could compete with the reaction glyoxal＋OH under certain atmospheric condi- tions. This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer.

关键词： Glyoxal Hydrolysis sulfuric acid acid-catalyzed mechanism

Study on mechanisms of different sulfuric acid leaching technologies of chromite

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 983-990页

作者： Pei-yang Shi Cheng-jun Liu Qing Zhao Hao-nan Shi Key Laboratory for Ecological Metallurgy of Multimetallic Ores Northeastern University Northeastern University School of Metallurgy Northeastern University Faculty of Chemical Environmentaland Biological Science and TechnologyDalian University of Technology

The extraction of chromate from chromite via the sulfuric acid leaching process has strong potential for practical use because it is a simple and environmentally friendly process. This paper aims to study the sulfuric acid leaching process using chromite as a raw material via either microwave irradiation or in the presence of an oxidizing agent. The results show that the main phases in Pakistan chromite are ferrichromspinel, chrompicotite, hortonolite, and silicate embedded around the spinel phases. Compared with the process with an oxidizing agent, the process involving microwaves has a higher leaching efficiency. When the mass fraction of sulfuric acid was 80% and the leaching time was 20 min, the efficiency could exceed 85%. In addition, the mechanisms of these two technologies fundamentally differ. When the leaching was processed in the presence of an oxidizing agent, the silicate was leached first and then expanded. By contrast, in the case of leaching under microwave irradiation, the chromite was dissolved layer by layer and numerous cracks appeared at the particle surface because of thermal shock. In addition, the silicate phase shrunk instead of expanding.

关键词： chromite leaching mechanisms microwave leaching sulfuric acid microanalysis