Extraction Of Platinum Metals With 2-Mercaptobenzothazole-functionalized Ionic Liquids

The shortage of global resources and environmental pollution have gradually become serious,environmental protect and high-efficient utilization of resources caused people's concern,as well as the recovery of platinum metals and recycle of these metals become more and more important due to the limited resources and increasing demand of platinum metals.Ionic liquids as green and non-pollutant organic salts have become research hot topic,owing to their unique thermodynamic properties.Ionic liquids have been widely used in the organic reaction,electronic chemistry,desulfurization and separation fields,especially,separation area has become one of the most attractive focus.Recently,a series of achievements have been obtained about the usage of ionic liquids as either extraction solvents or extractants in the separation area.However,there exist some bottlenecks that limited the application of ionic liquids in the extraction.On the one hand,the universal ionic liquids have week complexing ability on platinum metals.On the other hand,the separation between platinum metals has always become focus because of their similar physical and chemical properties.Hence,development and synthesis of particular functional ionic liquids has become one of effective methods for platinum separation and it needs to enrich development further.2-Mercaptobenzothiazole-functionalized ionic liquids are the introduction of 2-Mercaptobenzothiazole into the anions of ionic liquids,this type of ionic liquids have strong complexing ability for platinum metals,as a kind of extractants exhibit excellent extractability for platinum metals.This thesis designed and synthesized 2-Mercaptobenzothiazole-functionalized ionic liquids,then applied these functional ionic liquids into the extraction of palladium and ruthenium.Meanwhile,the high-efficiency separation of platinum and palladium has been achieved.The main research content and results as follows:Firstly,synthesis of 2-Mercaptobenzothiazole-functionalized ionic liquid and liquid-liquids extraction system was constructed for Palladium separation.Firstly,a novel 2-Mercaptobenzothiazole-functionalized ionci liquid(1,10-Bis(3-methylimidazolium-1-yl)decane bis(triflic)imide two 2-Mercaptobenzothiazolate,{[Cio(mim)2]2+ 2[MBT]-})with excellent selectivity for Pd(?)extraction was fabricated.Variable factors(e.g.,2-Mercaptobenzothiazole-functionalized ionic liquid concentration,hydrochloric acid concentration,sodium chloride concentration,sodium nitrate concentration and hydrogen ion concentration)were also investigated for extraction experiments.Accordingly,a special complexation extraction mechanism was proposed and confirmed by further experiments.Moreover,higher selectivity towards Pd(?)extraction was realized over other metal ions especially Pt(IV).Furthermore,0.5 M thiourea/1.0 M HCI was recognized as an efficiency stripping agent for Pd(?)loaded organic phase.Consequently,together with high efficiency and selectivity,the,2-Mercaptobenzothiazolate-functionalized ionic liquid can act as high selective extractant for Pd(?)extraction.Secondly,an arisen and environment-friendly method of cloud point extraction(CPE)which involved Octylphenoxypolyethoxyethanol(TX-114)as surfactant and2-Mercaptobenzothiazole-functionalized ionic liquid as extractant was carried out to separate Ru(?)from aqueous phase to bottom surfactant phase for the first time.A host of variable(e.g.,the extractant concentration,hydrochloric acid concentration,nitric acid concentration,TX-114 mass fraction,TX-114 volume and sodium chloride concentration)were evaluated and optimized to investigate the extraction behavior.At optimized experimental conditions,the extraction percentage of Ru(?)was found to be 82%,together with the enrichment factor of 40.A special complexation extraction mechanism of Ru(?)in CPE process was studied systemically and confirmed via job method,UV-vis spectrum and FT-IR spectrum in detail.Taking together,2-Mercaptobenzothiazole-functionalized ionic liquid could act as excellent extractant with superior extractability for Ru(?)extraction in CPE system.Thirdly,an investigation on a process designed for separating Pt(?)and Pd(?dissolved using 2-Mercaptobenzothi azole-functionalized ionic liquids based liquid-liquid extraction system.The conditions of equivalent time,the ratio of aqueous phase and organic phase,extractant concentration,hydrochloride acid concentration and sodium chloride concentration were rationally investigated and optimized for providing efficiency recoveries.Under the optimum condition,the separation factor of Pd(?)and Pt(?)can reach approximately more than 1558.This method for separating Pd(?)and Pt(?)with large separation factor is superior to the other separation systems by comparison,it can separate Pd(?)and Pt(?)quickly.Meanwhile,the extraction mechanism of Pd(?)and Pt(?)was confirmed by FT-IR and the similar extraction mechanism of metal complexing was obtained.In conclusion,Pd(?)and Pt(?)can separate in a quick and provide a high-efficiency approach for Pd(?)and Pt(?)separation in this system.