| With similar properties and valence variable between palladium and platinum, the separation of palladium from platinum was a major problem in modern metallurgy. Separation method of palladium from platinum commonly included precipitation, ion exchange and solvent extraction method, etc. Precipitation method needs long time with complicate operation process, ion exchange method is poor selectivity, solvent extraction method is harmful to the environment. This dissertation provided a new method of solid phase extraction (SPE) of platinum and palladium with high separation efficiency, less environmental pollution, polymer microspheres as the stationary phase.This dissertation consisted of several aspects experiments as followings:synthesis of stationary phase for solid phase extraction, screening of separation condition,analysis of thermodynamics and dynamics and mechanism research of solid phase extraction.Six kinds of new extractants:4-Methyl-2-octylsulfanyl-thiazole(MTOS),2-Heptyl-sulfanyl-1-methyl-1H-imidazole(HMIS),2-(2-Ethyl-hexylsulfanyl)-4-methyl-1H-imidazole (EHMIS),4-Methyl-2-(octane-1-sulfinyl)-thiazole(MTOSO),2-(Heptane-1-sulfinyl)-1-methyl-1H-imidazole(HMISO) and2-(2-Ethyl-hexane-1-sulfinyl)-4-methyl-lH-imidazole(EHMISO), which had not been reported, were synthesized and their structures were characterizated by IR,1H NMR,13C NMR and MS. A according to the related literature,2-hexylsulfanyl-1-methyl-lH-imidazole(HMHS),2-hexyl-sulfany1-5-methyl-1H-benzimidazole(HMHBS) and2-Octylsulfanyl-4,5-dihydro-thiazole (DTOS) were also synthesized.In this dissertation, polymer microspheres were used as support of the resin, extraction agents were embedded in the polymer microspheres by suspension polymerization method, which was made stationary phase of solid phase extraction, and synthesis conditions of the stationary phase were studied and the structures of the resins were characterized by scanning electron microscopy and BET nitrogen adsorption method, etc. HMHS, DTOS and MTOS three solid phase extraction separation palladium and platinum system was established through static adsorption method. On this basis, the factors affected solid phase extraction and separation were studied, such as adsorption capacity, extraction acidity, selectivity, elution conditions and recovery rate.The results showed that palladium(Ⅱ)(Cpd(Ⅱ)<400mg/L) could be effectively extracted by three kinds of stationary phase for SPE in the media of0.1mol/L hydrochloric acid, The single-stage extraction rate is reached97.0%, Thiourea was the effective eluting agent. The stripping rate was greater that96.5%, the recovery rate of Pd(Ⅱ) was over93.6%. The separation factors βPd/pt of three kinds of solid phase extraction were more than103, The extraction rates of Pt(Ⅳ), Rh(Ⅲ), Cu2+, Ni2+, Zn2+, Fe3+were<3.8%, Pd(Ⅱ) and Pt(Ⅳ) could be effectively separated by the SPE systems. In addition, Pd(Ⅱ) and Rh(Ⅲ), Cu2+, Ni2+, Zn2+, Fe3+were separated, respectively.Thermodynamic and kinetic studies showed that the three kinds of SPE were endothermic reaction, and the AH>40kJ/mol, Which were consistent with chemical adsorption and the quasi two level dynamics equation. The results showed that the adsorption data fit Langmuir adsorption isotherm.The mechanism of extracting Pd(Ⅱ) with all the three kinds resins were determined to be coordination replacing by UV-Vis spectrometry, infrared spectrometry and equimolar series method research. The mechanism of three kinds resins extraction of Pd(Ⅱ). The extractants coordinated with Pd(Ⅱ) via N or S atom. The molar ratio of Pd(Ⅱ) to ligand was1:2.The solid phase extraction (SPE) technology is the combination of high selectivity solvent extraction and simple operation ion exchange. SPE overcomes the shortcomings of the traditional solvent extraction agent which is easy to loss extraction agent and poor selectivity of ion exchange, SPE is a new simple and efficient technology of separation and concentration, Which can be used to separate palladium of in mixture solution. |
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