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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 method.It 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 ratio.Furthermore,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change of solubility of recently available Gum Xanthan(GX) from the market means that the original protocol is no longer applicable,and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of GX.We 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 TEP.The 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 analysis.The 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 TEP.The 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 TEP.It 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

Recovery of Li, Ni, Co and Mn from spent lithium-ion batteries assisted by organic acids: Process optimization and leaching mechanism

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International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 518-530页

作者： Liuyi Ren Bo Liu Shenxu Bao Wei Ding Yimin Zhang Xiaochuan Hou Chao Lin Bo Chen School of Resources and Environmental Engineering Wuhan University of TechnologyWuhan 430070China State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control Wuhan University of Science and TechnologyWuhan 430081China Zhejiang New Era Zhongneng Recycling Technology Co. LtdShaoxing 312000China Shenzhen Water Planning&Design Institute Co. LtdShenzhen 518000China

The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.

关键词： spent lithium-ion batteries leaching response surface methodology sulfuric acid citric acid

sulfuric acid leaching kinetics of South African chromite

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International Journal of Minerals,Metallurgy and Materials 2015年第3期22卷 233-240页

作者： Qing Zhao Cheng-jun Liu Pei-yang Shi Bo Zhang Mao-fa Jiang Qing-song Zhang Ron Zevenhoven Henrik Saxén Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education) Northeastern University Thermal and Flow Engineering Laboratory bo Akademi University

The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching con- ditions. The dimensionless change in specific surface area and the conversion rate of the chromite were observed to exhibit a proportional re- lationship. A modified shrinking particle model was developed to account for the change in reactive surface area, and the model was fitted to experimental data. The resulting model was observed to describe experimental findings very well. Kinetics analysis revealed that the leach- ing process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ.mol-1.

关键词： chromite ore treatment sulfuric acid leaching kinetics physical models

A theoretical study of hydrogen-bonded molecular clusters of sulfuric acid and organic acids with amides

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Journal of Environmental Sciences 2021年第2期33卷 328-339页

作者： Chenpeng Zuo Xianwei Zhao Hetong Wang Xiaohui Ma Siyuan Zheng Fei Xu Qingzhu Zhang Shenzhen Research Institute Shandong UniversityShenzhen 518057China Enuironment Research Institute Shandong UniversityQingdao 266237China

Amides,a series of significant atmospheric nitrogen-containing volatile organic compounds(VOCs),can participate in new particle formation(NPF)throught interacting with sulfuric acid(SA)and organic acids.In this study,we investigated the molecular interactions of formamide(FA),acetamide(AA),N-methylformamide(MF),propanamide(PA),Nmethylacetamide(MA),and N,N-dimethylformamide(DMF)with SA,acetic acid(HAC),propanoic acid(PAC),oxalic acid(OA),and malonic acid(MOA).Global minimum of clusters were obtained through the association of the artificial bee colony(ABC)algorithm and density functional theory(DFT)calculations.The conformational analysis,thermochemical analysis,frequency analysis,and topological analysis were conducted to determine the interactions of hydrogen-bonded molecular clusters.The heterodimers formed a hepta or octa membered ring through four different types of hydrogen bonds,and the strength of the bonds are ranked in the following order:SO-H···O>CO-H···O>N-H···O>C-H···O.We also evaluated the stability of the clusters and found that the stabilization effect of amides with SA is weaker than that of amines with SA but stronger than that of ammonia(NH 3)with SA in the dimer formation of nucleation process.Additionally,the nucleation capacity of SA with amides is greater than that of organic acids with amides.

关键词： Amides sulfuric acid Organic acids Hydrogen bond Nucleation

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 sulfi.Lric 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/（L.min）, 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/（L.min）. With the hy- drolysis rate between 0.02 and 0.03 g/（L.min）, 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

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

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 evaporation.The 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 water.This process was named as Chemical Dehydration Process.The residual water was further removed by two-effect evaporation and finally 70 wt%sulfuric acid was obtained.The FeSO4·H2O can be regenerated through drying and dehydration of FeSO4·7H2O.The 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 acid.This chemical dehydration process is also energy efficient with 24.76%saving compared with the direct evaporation process.Furthermore,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

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