| Gold not only plays an important role in the economic activities of human society,it is also widely used in industrial fields such as electronics,catalysis,electroplating,and fuel cells.Due to the depletion of natural mineral resources and the growing demand for gold,it is becoming increasingly important to recover gold from low-grade materials.Therefore,it is of great practical significance to develop a technology for efficient extraction of gold from a low-concentration gold-containing chlorinated solution.Solvent extraction requires a large amount of organic solvents to extract low-concentration gold from hydrochloric acid.Many organic solvents are flammable,highly volatile,and pose a risk of poisoning and pollution to the environment.Aiming at the problems of solvent extraction technology,this paper carried out the research on the extraction of Au(III)from acidic solution by polymer chimeric membrane(PIM).PIM membrane technology uses a very small amount of ionic liquid as a carrier to combine the extraction and back extraction processes into one step.It has the advantages of high extraction efficiency,good membrane stability,and environmental friendliness.This method provides a green and efficient separation technology for the efficient recycling of low-concentration gold ions.1.Preparation of two kinds of ILs[A336][P507]and[A336][P204],characterization using some characterization methods,which are include nuclear magnetic resonance,infrared and mass spectrometry.The extraction ability of gold(III)in HCl solution was studied separately.The effects of parameters such as the reaction equilibrium time,the reaction temperature,the HCl concentration in the feed liquid phase,the ionic liquid concentration in the feed liquid phase,the initial concentration of gold(III),and the NaCl concentration were investigated.The results show that under the optimal conditions,the extraction efficiency of[A336][P507]and[A336][P204]for gold can reach 99.96%and 99.92%,respectively.Analysis of the extraction mechanism of gold using the ionic liquid[A336][P507]using infrared and ultraviolet spectroscopy,and the results show that the ionic liquid anion[P507]-has coordinated reaction with gold to generate AuCl3?[A336][P507]extract.At the same time,the gold in the gold-containing ionic liquid can be back-extracted with acidic thiourea or sodium sulfite.2.[A336][P507]was used as the extraction agent,NPOE was used as the plasticizer,and PVDF was used as the polymer backbone to successfully prepare the polymer chimeric membrane(PIM).The characterization methods such as thermogravimetry,contact angle,and scanning electron microscopy were used to characterize it.The results show that the synthesized PIM has a flat surface and a large pore channel in the membrane,which is conducive to the extraction reaction.The extraction of gold(III)in acidic environment was studied using synthetic PIM.The effects of parameters such as the composition of the polymer chimeric membrane,the concentration of HCl,the concentration of NaCl,the concentration of Na2SO3,and the initial concentration of gold(III)were investigated.Optimal process conditions.When the composition of the membrane is 60 wt%PVDF-30 wt%[A336][P507]-10 wt%NPOE,under the optimal conditions,when the reaction time reaches 24 h,the extraction rate of gold(III)by the system And stripping rates were 99.08%and 95.86%,respectively.The mass transfer kinetics of gold is studied,and the results show that the mass transfer coefficient of gold can reach 12.25×10-6 m/s.3.In order to further improve the mass transfer efficiency of the PIM separation process,a method of PIM extraction-electrodeposition cooperative recovery of gold was designed.With 50 wt%PVDF-40 wt%[A336][P507]-10 wt%NPOE as the PIM membrane,a voltage is applied in the back extraction phase,and gold migrates from the phase to be extracted through the PIM membrane to the back extraction phase and is electrodeposited on Copper electrode.The effects of parameters such as HCl concentration,electrolytic voltage,Na2SO3 concentration,NaCl concentration,and polymer chimeric membrane composition were investigated to optimize the optimal process conditions.The results showed that the extraction rate and deposition rate of gold(III)for PIM synthesized with[A336][P507]as the carrier were 99.26%and97.91%,respectively,while the residual gold in the back extraction phase was only1.33%.At the same time,it was found that the migration rate of gold was greatly increased after applying a voltage in the back-extraction phase.The mass transfer coefficient of gold increased significantly from 18.22×10-6 m/s in the absence of voltage to 26.95×10-66 m/s when a voltage of 1.50 V was applied.The PIM collaborative electrodeposition method has achieved the purpose of extraction and electrodeposition,and provided new research ideas for future industrial applications,and its development prospects are inestimable. |
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