Synthesis And Apllication Of Cr(Ⅵ)-imprinted Polymer

Chromium（Ⅵ）, as an internationally recognized carcinogen, causes a serious threat tohuman, water resources and soil. Chromium pollution is related with wood preservation,leather tanning, electrofacing and metal processing. The adsorption method is one of the mostcost-effective methods of chromium （Ⅵ） removal. As a novel adsorbent, ion imprintingpolymer has attracted more attention due to its high adsorption capacity, high selectivity andreusability. In the paper, three Cr（Ⅵ） ion imprinting polymers were synthesized by solutionpolymerization, emulsion polymerization and surface-grafted ion imprinted polymers. Thepolymers were characterized by FT-IR, TG, SEM, VSM and EDX. And the main conclusionshad been drawn as follows:1. Cr（Ⅵ）-ion imprinting polymer（IIP） based on1-vinyl-imidazole （1-VDA） as thefunctional monomer was prepared by solution polymerization. The effects of synthetic factorson adsorption ability, such as the kinds and amounts of co-monomer, cross-linking agent andsolvent were discussed. The IIP was synthesized by^2-Hydroxyethyl Methylacrylate （HEMA）as co-monomer, ethylene glycol dimethacrylate （EGDMA） as cross-linking agent, water andisopropyl alcohol solution as solvent, Cr₂O₇^2-, CrO₄^2-and HCrO₄^-as ion templates. The resultsof adsorption experiments showed that the three IIPs exhibited high selectivity and goodrecognition ability for their own template, and their adsorption capacities were107.92mg·g^-1、78.63mg·g^-1and75.78mg·g^-1, respectively.2. Cr（Ⅵ）-ion imprinting microspheres were prepared by emulsion polymerization usingphenylethylene （St） as polymer matrix, Cr₂O₇^2-, CrO₄^2-and HCrO₄^-as ion templates, Span80as emulsifier, EGDMA as crosslinking agent, polyvinyl alcohol（PVA） as dispersing agent.The morphology of microspheres was shaped by many factors including the amount of PVAand emulsifier, stirring rate, temperature. The results of adsorption experiments revealed thatthe three IIPs exhibited high selectivity and good recognition ability for their own template,and their adsorption capacities were78.94mg·g^-1,50.53mg·g^-1and29.36mg·g^-1, respectively.3. A novel Cr（Ⅵ） magnetic ion imprinting polymer was prepared via surface ion imprinting polymerization. Fe₃O₄magnetic particles were modified by oleic acid. Theoptimum synthesis conditions including the amount of crosslinking agent, initiator and oleicacid were determined. The adsorption results indicated that the adsorption capacities ofCr₂O₇^2-, CrO₄^2-and HCrO₄^-were118.06mg·g^-1、91.62mg·g^-1�'�89.69mg·g^-1, respectively.4. By comparison, surface ion imprinting polymerization was better than solutionpolymerization and emulsion polymerization. The effects of Cr （Ⅵ） condition, pH, theamount of polymer, particle size, adsorption time and adsorption temperature on adsorptionproperties of magnetic ion imprinting polymer were discussed. Besides, the isotherms werealso studied. The selectivity studies showed that magnetic ion imprinting polymer had goodselectivity. IIP had higher adsorption capacity comparing with commercial resins. Finally,readabilities were discussed.