浓盐酸表面薄层分子识别优先分离铑  

Preferential separation of rhodium by molecular recognition on surface of concentrated hydrochloric acid

作　　者：杨之焯 周海涛 吴雪琴 肖列发 王佳琦 黄焜 YANG Zhizhuo;ZHOU Haitao;WU Xueqin;XIAO Liefa;WANG Jiaqi;HUANG Kun(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;Beijing Key Laboratory of Green Recovery and Extraction of Rare and Precious Metals,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]北京科技大学稀贵金属绿色回收与提取北京市重点实验室,北京100083

出　　处：《中国有色金属学报》2024年第9期3114-3124,共11页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(52074031,51574213)。

摘　　要：Rh(Ⅲ)氯络阴离子的动力学惰性和易水化特性使其难以在传统溶剂萃取过程中优先于其他共存铂族金属离子分离。本文提出一种采用分子识别剂苯并-15-冠醚-5(B15C5)选择性优先分离浓盐酸中Rh(Ⅲ)氯络阴离子的薄层油膜萃取新方法。考察了水相流速和油膜厚度对Rh(Ⅲ)、Pd(Ⅱ)、Pt(Ⅳ)萃取率及其彼此间分离系数的影响。结果表明:与传统分散油滴搅拌萃取法相比,在浓盐酸表面执行薄层油膜萃取可实现Rh(Ⅲ)>Pd(Ⅱ)>Pt(Ⅳ)的选择性识别分离顺序。由于Rh(Ⅲ)氯络阴离子的水化能力强于Pd(Ⅱ)和Pt(Ⅳ)氯络阴离子,在进入Rh(Ⅲ)氯络阴离子内界配位的水分子以及Rh(Ⅲ)氯络阴离子周围水化壳层的共同作用下,Rh(Ⅲ)氯络阴离子与B15C5分子间通过水分子为“桥”的氢键相互作用更强。同时,由于浓盐酸表面自由H_(3)O^(+)浓度较低,油膜层下方水相流速的增加有利于促进界面处Rh(Ⅲ)氯络阴离子水化,油膜层厚度的减小则有助于界面更新,从而强化了Rh(Ⅲ)与Pd(Ⅱ)、Pt(Ⅳ)的分离。The kinetic inertness and easily hydrated characteristics of Rh(Ⅲ)chloric-complexing anions render it difficult to separate them preferentially from other coexisting platinum group metal ions in conventional solvent extraction.This work proposed a novel molecular recognition method based on thin-layer oil film extraction for selective and preferential separation of Rh(Ⅲ)chloric-complexing anions in concentrated hydrochloric acid using benzo-15-crown ether-5(B15C5).The effects of the flow rate of aqueous phase and thickness of oil film on the extraction rates of Rh(Ⅲ),Pd(Ⅱ)and Pt(Ⅳ),and the separation factors between them were investigated.The results indicate that,compared with the conventional dispersed oil droplet stirring extraction method,the performing thin-layer oil film extraction on the surface of concentrated hydrochloric acid can achieve a selective recognition separation sequence of Rh(Ⅲ)>Pd(Ⅱ)>Pt(Ⅳ).Due to the stronger hydration ability of Rh(Ⅲ)chloric-complexing anions compared with Pd(Ⅱ)and Pt(Ⅳ),the H_(2)O molecules entering the inner coordination sphere of Rh(Ⅲ)chloric-complexing anions and the hydration shell around Rh(Ⅲ)chloric-complexing anions work together,resulting in stronger hydrogen bonding interactions between Rh(Ⅲ)chloric-complexing anions and B15C5 molecules through the H_(2)O molecules acting as"bridges".Meanwhile,due to the lower concentration of free H_(3)O^(+)on the surface of concentrated hydrochloric acid,the increase in flow rate of aqueous phase beneath the oil film layer facilitates the hydration of Rh(Ⅲ)anions at the interface,while the decrease in the thickness of oil film promotes the interfacial renewal,thus enhancing the separation of Rh(Ⅲ)with Pd(Ⅱ)and Pt(Ⅳ).

关 键 词：铑 浓盐酸 表面 薄层油膜 分离 分子识别 

分 类 号：TF83[冶金工程—有色金属冶金]