P507对硫酸介质中Ⅴ(Ⅳ)/Fe(Ⅱ)分离性能和萃取机制研究  

Extraction and Separation Performance and Mechanism of Ⅴ(Ⅳ)and Fe(Ⅱ)in Sulfuric Acid Medium by P507

作　　者：刘月 李望 朱晓波[1,2,3] Liu Yue;Li Wang;Zhu Xiaobo(College of Chemistry and Chemical Engineering,Henan Polytechnic University,Jiaozuo 454000,China;State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,Wuhan University of Science and Technology,Wuhan 430081,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Jiaozuo 454000,China)

机构地区：[1]河南理工大学化学化工学院,河南焦作454003 [2]武汉科技大学,国家环境保护矿冶资源利用与污染控制重点实验室,湖北武汉430081 [3]煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作454000

出　　处：《稀有金属》2023年第6期843-853,共11页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51904097,51804103);河南省自然科学基金项目(232300420078);国家环境保护矿冶资源利用与污染控制重点实验室开放基金课题(HB202106);河南省科技攻关项目(232102321138)资助。

摘　　要：研究了硫酸体系中酸性含磷萃取剂2-乙基己基磷酸2-乙基己基酯(P507)对Ⅴ(Ⅳ)及Fe(Ⅱ)萃取分离性能和萃取机制。萃取实验考察了水相初始pH,温度、萃取剂浓度对Ⅴ(Ⅳ)萃取性能的影响,探究了相比对萃取分离Ⅴ(Ⅳ)和Fe(Ⅱ)性能的影响。结果表明:在钒、铁浓度(C)分别为C_(Ⅴ)=0.22 g·L^(-1)和C_(Fe)=0.5 g·L^(-1)的原料液条件下,萃取温度为室温、有机相体积组成为20%P507+80%磺化煤油、水相初始pH=2,相比(O/A)=1∶6及萃取时间为5 min时,Ⅴ(Ⅳ)的萃取率达到96%,而Fe(Ⅱ)的萃取率仅为8%,分离系数达到291,Ⅴ(Ⅳ)与Fe(Ⅱ)可有效分离。萃取热力学实验先采用饱和容量法研究了当水相初始pH值为2时,P507对Ⅴ(Ⅳ)的萃取机制,结果显示萃合物中Ⅴ(Ⅳ)与P507的摩尔比,即萃合比([Ⅴ]/[P507])为1∶2,并得到相应的萃取方程。再考察不同萃取液pH值、萃取剂浓度及萃取温度对Ⅴ(Ⅳ)和Fe(Ⅱ)分配比的影响,计算得萃取Ⅴ(Ⅳ)和Fe(Ⅱ)反应的平衡常数(K)、焓变(ΔH)、自由能变(ΔG)及熵变(ΔS)。其中平衡常数KⅤ=1×10^(-2.35),KFe=1×10^(-2.95)说明在室温时,该体系条件对Ⅴ(Ⅳ)的萃取更完全,反应得也更彻底。ΔH(Ⅴ)=8.48 kJ·mol^(-1),在较低温度时ΔH(Fe)_(1)=38.96 kJ·mol^(-1),而在较高温度时ΔH(Fe)_(2)=-21.31 kJ·mol^(-1)表明低温下该萃取过程为吸热反应,温度的升高导致萃取率不断提升。ΔG(Ⅴ)=5.7 kJ·mol,ΔS(Ⅴ)=9.32 J·K^(-1)·mol^(-1),ΔG(Fe)=16.8 kJ·mol^(-1),较低温度时ΔS(Fe)_(1)=74.3 J·K^(-1)·mol^(-1)以及较高温度时ΔS(Fe)_(2)=-127.8 J·K^(-1)·mol^(-1),ΔG(Ⅴ)<ΔG(Fe)证明了该萃取体系是优先萃取Ⅴ(Ⅳ)的,且萃取Ⅴ(Ⅳ)比萃取Fe(Ⅱ)更加完全,与Ⅴ(Ⅳ)形成的萃合物也更加稳定。分别对纯P507及萃取Ⅴ(Ⅳ)后有机相和萃取Fe(Ⅱ)后有机相进行红外光谱分析,进一步说明萃取主要发生在P-OH上。且由于钒氧双键与萃取剂P507的磷羟基形成了P-π共轭键,故与FeVanadium was a high melting point rare metal with ductility,which had been widely used in steel,aerospace,chemical industry(catalyst),battery and materials.Vanadium was also one of the most abundant elements in the surface of the earth's crust.Both the demand and application of vanadium showed that vanadium was in short supply all over the world.Vanadium could not form a separate vanadium deposit,which usually existed in the form of vanadium bearing minerals or isomorphism.The recovery of vanadium resources was mainly acid leaching,alkali leaching and water leaching,among which acid leaching was the most efficient and widely used leaching method.Vanadium containing minerals eventually formed vanadium containing leaching solution.In the leaching process,many impurities inevitably entered the aqueous phase.Among them,the influence of iron impurity was the most significant one.How to efficiently separate vanadium and iron impurities from sulfuric acid leaching solution had become one of the key problems.Solvent extraction in vanadium extraction process had the characteristics of easy industrialization,simple equipment,low investment,high production efficiency,simple process and high purity of products.At present,the separation methods of iron and vanadium in sulfuric acid solution could be basically divided into two categories in principle:one was to use the property that vanadium preferentially generates polymeric anions in the acidic range.Second,the effective separation of iron and vanadium from sulfuric acid solution could be realized by using the nature that iron was easier to generate cations under acidic conditions and separation methods such as solvent extraction and adsorption.The selection of extractant di(2-ethylhexyl)phosphate(P507)for the optimal conditions of Ⅴ(Ⅳ)and Fe(Ⅱ)extraction and separation in sulfuric acid medium was studied.The effects of pH,temperature,extractant concentration and ratio of aqueous phase on vanadium extraction performance were investigated.The results showed that when th

关 键 词：2-乙基己基磷酸2-乙基己基酯(P507) Ⅴ(Ⅳ) Fe(Ⅱ) 萃取 热力学 

分 类 号：TF803.23[冶金工程—有色金属冶金]