Study On Development Of Functional Polymer Membrane Electode And Its Adsorption And Desorption Process For Uranium In Seawater

The nickel film was used as the base material,the surface of nickel was modified and assembled to form the functional polymer membrane electrode.P(AN-VAc)copolymer was synthesized from acrylonitrile and vinyl acetate by aqueous deposited polymerization,and P(AN-VAc-VA-AA)with hydroxyl groups and carboxyl groups was treated under basic conditions.Then,ferrocene group modified polyurethane prepolymer with certain electrical conductivity and forced reduction properties were synthesized.The products were characterized by FT-IR,1H-NMR,TGA and DSC.KH-550,modified polyurethane prepolymer and P(AN-VAc-VA-AA)were assembled to pretreated nickel sheet in turn,and then functional membrane electrode with carboxyl and amidoxime groups was obtained by hydroxylamine hydrochloride neutral solution.The surface morphology of each step in the assembly process of membrane electrode were observed using SEM;The fluorescence spectrophotometry was used to determine the adsorption of uranium ions by functional membrane electrode,the effects of time,pH conditions and adsorption temperature on the adsorption performance of the membrane electrode were investigated.The electrochemical behavior of the electrode was investigated by cyclic voltammetry.(1)The functional polymer with carboxyl group was prepared by mixing with ferrocene group modified polyurethane prepolymer in DMSO.The optimum time for self-assembly was 10 min.The functional polymer membrane electrode was prepared with 0.01 mol L-1 hydroxylamine hydrochloride neutral solution in 0.5 h.(2)Synthesis of PU prepolymer with ferrocene functional group.The ferrocenyl group was introduced into the isocyanate in the form of ?-hydroxyethyl ferrocene.The amount of material used was Fc-CHOHCH3:HDI:TMP=1:3:1(molar ratio),The best condition for the reduction of ?-hydroxyethyl ferrocene from acetylferrocene was prepared by the reaction of FcCOCH3:CuSO4:NaBH4=1:3:3(molar ratio)for 1.6 hours under 0?;the solvent of PU prepolymer was DMSO.(3)The concentration of uranyl nitrate in the solution was determined by fluorescence spectrophotometry,and the optimal detection conditions: the fluorescence enhancer was 2.4% and p H=7.(4)The function of electrode at room temperature and neutral 1 ?g m L-1 uranyl nitrate standard solution,eight hours reached the adsorption equilibrium state and the equilibrium adsorption capacity is 1.67 mgU g-1,and from room temperature to 35 ?,with the increase of temperature,the adsorption reached equilibrium faster.(5)Cyclic voltammetry was used to characterize the functional electrode.The electrochemical desorption voltage of the functional electrode in pH=6.8 phosphate buffer solution is-1.13 V.(6)The functional membrane electrodes was tested in natural seawater.At room temperature,when the adsorption time was 8 h,the adsorption capacity is 1.1 mgU g-1.