Extraction And Separation Of Platinum Group Metals Using Sulphur/Nitrogen Contained Ionic Liquids

Platinum group metals(PGMs)are improtant metal resources in national military defense and industrial,is and medical treatment,have drawn extensive attention.However,the shortage of mineral resources of PGMs restricts their utilization and applications,and so recovering and recycling these materials from secondary resources provide a solution for people to take advantage of PGMs.In this article,the efficient extraction and separation of PGMs was realized by synthesis functionalized ionic liquids or construct two aqueous phase system.The extraction mechanism was explored through theoretical calculation,X-ray single crystal diffraction analysis,spectral analysis methods.Some influence factors such as HCl,extractant concentration were investigated to optimize the extraction process.Meanwhile,separation of Pd-Ru and Pt-Ir,which have similar extractino mechanism,was realized by adjusting extraction conditions or the reducibility of metals.Details are as follows:1)Separation of Pd,Ru and Rh in liquid-liquid extraction with functionalized ionic liquid[C6min][DDTC].A reasonable project was presented for the extraction and separation of Pd(?),Ru(?),and Rh(?)from the mixed imidazolium-based ionic liquids(ILs)[C6mim]Cl,[C6mim][NTf2],and[C6mim][DDTC].[C6mim]Cl shows poorly extractability for PGMs and the introduction of[DDTC]-can change the disadvantages.Mechanisms between Pd(?)/Ru(?)and[C6mim][DDTC]were further explored using ultraviolet spectrophotometry(UV-Vis),infrared spectrophotometry(FTIR),the method of continuous variations,ab initio quantum chemical studies,and X-ray crystallographic analysis.The results afford more directions for extracting and separating metals by introducing devisable functionalized group into ILs.2)Behavior and mechanism investigation of separating Pt and Ir by liquid-liquid extraction using betain based[C6bet]Br.In the process of recovering platinum group metals by extraction,separation of Pt and Ir is very difficult because Pt(?)and Ir(?)show similar chemical properties and extraction behaviours in hydrochloric acid medium.In this paper,a betaine-based ionic liquid[C6bet]Br was firstly applied to the separation of Pt(?)and Ir(?).[C6bet]Br showed remarkable precipitation performance of Pt(?)and Ir(?).The impactful extraction was realized by importing[C6mim][NTF2]as the hydrophobic phase with extraction efficiencies of ca.99%and 88%under optimal conditions.A selective reduction process for Ir(?)was firstly proposed for the separation of these two similar PGMs by using hydroxylamine hydrochloride(NH2OH·HCl).The mechanism of extracting Pt(?)/Ir(?)using[C6bet]Br was confirmed to be an anionexchange process by spectroscopic analysis(UV-Vis,FT-IR,1H NMR)and the method of continuous variation.The electrostatic potential map of[C6bet]Br was calculated for the first time to confirm the anion-exchange mechanism.8 M HCl was effective for the back extraction of Pt(?)and Ir(?).3)Extraction of Rh(?)with two aqueous phase system using betain based ionic liquid and salt.A two aqueous phase system was built with[C6bet]Br and salt for the extraction of Rh(?)which is difficult to be extracted in traditional liquid-liquid extraction.The contract of two aqueous phase system could extract 95%of Rh(?).The result suggested that[C6bet]Br-NaH2PO4 and[C6bet]Br-Na3C6H5O7 system show best stability in Rh(?)extraction when the influenced factors changed.After extraction,(NH4)2S was used as precipitant for the recovery of Rh(?),and the obtained nanoscaled Rh2S3 particle showed excellent electrochemical catalytic ability in HCl electrolysis which was a significative recycling of raffinate.