Preparation And Properties Of Cd(Ⅱ)-Imprinted Thiol-Functionalized Micro-Bead Silica Gel Polymer

Ion imprinting technique (ⅡT) is becoming increasingly recognized as a powerful technique of preparing synthetic polymers that contain tailor-made recognition sides for certain Ions. It has an extensive application in separation and purification, immunoassay, enrichment, biomimics and other relevant fields for its predetermination specificity and practicability of ion recognition. The introduction of ion-imprinted polymers (ⅡP) in trace and ultratrace analysis provides vital breakthroughs in pre-concentration or separation chemistry.In this paper, a surface molecular imprinting technique on the surface of micro-bead silica gel particles was put forward, using grafting: firstly functional MPS was grafted on the silica gel particle surfaces via coupling grafting method; secondly ion imprinting was preformed using heavy-metal ion, Cd2+, as the template, which has been coordinated with MPS, and epichlorohydrin (ECH) as crosslinking agent; finally ion-imprinted composite material IIP-MPS/SiO2 was formed. The optimum processing conditions were investigated with reaction temperature, reaction time, the type of crosslinking agent and other factors to serve as targets.Effects of temperatures, times and pH conditions on adsorption capacity of IIP-MPS/SiO2 toward Cd2+ were studied. The results demonstrated that temperature had little effect on adsorption capacity and that very high adsorption efficiency was obtained at different temperatures (30-60℃). The best adsorption of IIP-MPS/SiO2 was observed when pH was in the range of 4-8. The adsorption rate was rather fast and adsorption equilibrium was formed within 20 min. Therefore, IIP-MPS/SiO2 could selectively remove Cd2+ in different water bodies.The binding characteristics ofⅡP-MPS/SiO2 for Cd2+ were studied in detail by adopting static methods. The experimental results showed that the ion-imprinting material IIP-MPS/SiO2 has specific recognition ability for the template ions, and this character displays mainly in two aspects:(1) it has high affinity for the template ions, its binding amounts for the template ions are much greater than that of the non-imprinted composite material MPS/SiO2 and the absorption capacity enhances more than two times compared to MPS/SiO2; (2) it has excellent selectivity for the template ions, for the IIP-MPS/SiO2 by using Cd2+as template ion, its selectivity coefficients relative to Ni2+, Zn2+, Cu2+ and Co2+ are 26.39,23.28,1.44 and 32.16, respectively. Besides, the imprinting material IIP-MPS/SiO2 has a fine elution property using HC1 solution as eluent.