Extraction Of Noble Meatals Using Silicone Ionic Liquid-based Systems From Hydrochloric

Noble metals occupies a vital position in national economy and industrial production for the advantages of stability,ductility,catalytic activity,small volume,corrosion resisting and high temperature resistance etc.However,the scarcity and intergrowth with base metals makes it a target of continuously exploring new separation approaches in accordance with time's requirement and reducing the environmental contamination and the resource consumption,which we should always pursue.In this paper,we are dedicated in applying silicone ionic liquids to build extraction systems for the separation and recovery of noble metals.Ionic liquids possess the function of extractant in all these extraction systems.Our main work has been listed below:First,[Si₄mim]Cl/PEG6000 and[C₆mim][C₁₂SO₃]/PEG6000 aqueous two phase systems were applied for gold???extraction for the first time.Ionic liquids,[Si₄mim]Cl and[C₆mim][C₁₂SO₃],were synthesized and used for the construction of aqueous two phase systems together with PEG6000 which were investigated for Au???extraction later.Both[Si₄mim]Cl and[C₆mim][Cl2SO3]acted as components of the aqueous two phase systems as well as the gold???extractant First,the phase diagrams of the[Si₄mim]Cl/PEG6000 and[C₆mim][C₁₂SO₃]/PEG6000 aqueous two phase systems was initially investigated.To optimize the process,the influence of several experimental parameters,namely the vibration time,the pH of the PEG stock solution,initial gold???concentration,the PEG molecular weight,was studied in the extraction process.At the optimum conditions,extraction percentage of gold???is up to 99.61%and 97.56%,respectively.Then,the ion-exchange mechanism of gold???extraction was discussed by UV-vis and FT-IR spectra in the process.It demonstrates that the[Si₄mim]Cl/PEG6000 aqueous two phase system has better extraction ability to gold???than[C₆mim][C₁₂SO₃]/PEG6000 aqueous two phase system and both of the aqueous two phase systems would be a promising and potential approach for gopd???extraction and separation in acid solutions.Second,the silicone ionic liquid,[Si₄mim]Cl,was first used for the construction of the W/O microemulsion system and the[Si₄mim]Cl/n-heptane/n-hexanol/NaCl microemulsion system was applied for palladium extraction firstly.The stability of[Si₄mim]Cl/n-heptane/n-hexanol/NaCl microemulsion system was characterized by the Turbiscan Lab.For the Pd???extraction by the[Si₄mim]Cl/n-heptane/n-hexanol/NaCl microemulsion system,primary parameters?namely,the vibration time,the[Si₄mim]Cl concentration,the phase ratio and the additives?affecting the palladium extraction was investigated to optimize the process.Under the optimum conditions,the extraction percentage of Pd???is up to 98%.Afterwards,the ionic-exchange mechanism of Pd???extraction by the[Si₄mim]Cl/n-heptane/n-hexanol/NaCl microemulsion system was confirmed by the Job Method and analyzed by FT-IR spectra.The stripping of Pd???from the microemulsion phase was also studied using the NaCl solutions,indicating a high striping efficiency.At last,the selectivity of the[Si₄min]Cl/n-heptane/n-hexanol/NaCl microemulsion system to Pd?II?from other metals?Cu???,Co???,Ni???,Fe???,Al???Zn???,Ce???,Li???,Mg???and Sn?IV??was demonstrated to be quite high.The results of our work indicate that the[Si₄min]Cl/n-heptane/n-hexanol/NaCl microemulsion system is apromising approach for Pd?II?extraction and can be used to separate palladium from base metals efficiently and rapidly.It is also the first time to applied silicone ionic liquid as extractant for metal extraction.Last,the high-efficient extraction and separation of Pt???,Rh???and Ru???was achieved by silicone ionic liquid/chloroform system.In this part,three silicone ionic liquids were utilized,namely[Si₄mim]Cl,[Si₄pyr]Cl and[Si₄pip]CI Via the study of the effect of the type and concentration of ionic liquids on the extraction behavior of these metals,it was found that the variation tendency of their extraction percentage all followed the order of[Si₄mim]Cl<[Si₄pyr]Cl<[Si₄pip]Cl.After the investigation of other influence factors,including the vibration time,HCl concentration and SnCl₂ concentration,it is discovered the extraction percentage of Pt???and Rh???can reach 99%at the optimum conditions,while extraction percentage of Ru???is very low at the corresponding circumstance.Based on the results,an approach to separate Pt???,Rh???and Ru???by the silicone ionic liquid/chloroform system was provided.Finally,the Job method and FT-IR spectra were applied to confirm the anion-exchange mechanism of Pt???.