Ion-imprinted beads for molecular recognition based mercury removal from human serum

The aim of this study is to prepare ion-imprinted polymers which can be used for the selective removal of mercury ions [Hg(2+)] from human serum. N-Methacryloyl-(L)-cysteine (MAC) was chosen as the complexing monomer. In the first step, Hg(2+) was complexed with MAC and the Hg(2+)-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-cysteine) (MIP) beads were synthesized by suspension polymerization. After that, the template ions (i.e., Hg(2+)) were removed using thiourea (0.5%, v/v) in 0.05 M HCl. The specific surface area of the MIP beads was found to be 59.04 m(2)/g with a size range of 63-140 micro m in diameter and the swelling ratio was 91.5%. According to the elemental analysis results, the MIP beads contained 87.0 micro mol MAC/g polymer. The maximum adsorption capacity was 0.45 mg Hg(2+)/g beads. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. The relative selectivity coefficients of MIP beads for Hg(2+)/Cd(2+), Hg(2+)/Zn(2+) were 14.7 and 21.5 times greater than the non-imprinted (NIP) matrix, respectively. The MIP beads could be used many times without decreasing in their adsorption capacities significantly.