Pdtu Series Of Polyester-thiourea Resin Synthesis Of Pt (iv), Pd (ii) Adsorption Properties And Mechanism Of The Study

Based on the evolution of thiourea resins and their adsorption to noble metals,polyester thiourea resins——PDTU were synthesized. Synthesis technology and their adsorption properties were studied in this paper.PDTU thiourea resins were synthesized by polymerization of disothiocyanadate and polyamines.Bischloroformate was prepared by the reaction of bis(trichdomethyl)carbonate and diethylene glycol,catalyzed by N,N-dimethylaniline(DMA);Secondly,oxydiethane-2,1-diyl diisothiocyanatidate(ITC)were synthesized by the solid-liquid phase transfer catalysis reaction of bischloroformate and KSCN;Finally,ITC polymerized with polyamines to prepare PDTU resins.Based on research about the third reaction,it can be concluded as follows:yield of PDTU resins are as high as 91.12%～92.05%under low temperature,when molar ratio of diethylene triamine and ITC is 1:1.PDTU resins were charaterized by IR,elemental analysis,SEM,TG and so on.With batch method,the influence of adsorption duration, temperature,initial concentration of noble metals,concentration of HCl was studied.Adsorption capacities of PDTU-Ⅲto Pt(Ⅳ)and Pd(Ⅱ)are 2.00 mmol·g^-1,3.41 mmol·g^-1respectively under the following conditions: temperature is 30℃,initial concentration of noble metals is 1 mg·mL^-1, concentration of HCl is 1 mol·L^-1.The adsorption process of PDTU-Ⅲto Pt(Ⅳ)and Pd(Ⅱ)reached equilibrium after 12 hours.Adsorption capacities increase with the increase of temparature,the initial concentration of noble metals,effected hardly by acidity in the solution. Separation factor K_d of binary system highly tangs from 150 to 340, which revealed favorable selectivity for the noble metals.Adsorption isotherm,thermodynamics,kinetics were researched, and the adsorption mechanism of PDTU resin to Pt(Ⅳ)and Pd(Ⅱ)was discussed.Isotherm adsorption process can be well described by Langmuir models,which indicats that the adsorption is a monolayer one; Enthalpy change△H of the process is plus,which demonstrated that adsorption process is endothermic;liquid film spreading is the predominant step of the adsorption process;IR and XPS contrastive analysis before and alter adsorption reveal that Pt(Ⅳ)and Pd(Ⅱ)accept electrons from S and O,and coordinate with the resins in the adsorption process.