Preparation, Characterization of Cd(II) Ion-Imprinted Microsphere and Its Selectivity for Template Ion

Abstract

Cadmium is one of the many toxic elements for humans even at low concentrations, and it could exist in the environment for a long time. The ion imprinting technique has gained much attention due to its selective recognition performance. In this study, a cadmium ion imprinted maleic acid-co-acrylonitrile polymeric microsphere (Cd-I-MA-co-AN) was synthesized via precipitation polymerization using Cd(II) as a template ion, acrylonitrile and maleic acid as functional monomers, divinylbenzene as a cross-linker, and potassium persulfate as an initiator. UV–vis, SEM and FTIR were used for characterization, and the adsorption conditions were observed and optimized. The adsorption capacity and selectivity of Cd-I-MA-co-AN for Cd(II) were analyzed by flame atomic absorption spectrometry (FAAS). The results documented that the optimal pH, flow rate and eluent were 6, 2 mL min−1 and 1 mol L−1 nitric acid, respectively. Compared with the non-ion imprinted maleic acid-co-acrylonitrile polymeric microsphere (NI-MA-co-AN), Cd-I-MA-co-AN had a higher adsorption capacity. The saturated adsorption capacities of Cd-I-MA-co-AN and NI-MA-co-AN were 20.46 mg g−1 and 7.64 mg g−1, respectively. The adsorption behavior of Cd-I-MA-co-AN fitted with the Freundlich isotherm model. The relative selectivity coefficients of Cd-I-MA-co-AN for Cd(II) in the presence of Cu(II), Mn(II), Ni(II) and Pb(II) were 3.79, 3.39, 3.90 and 3.31, respectively. The Cd-I-MA-co-AN showed good selectivity for Cd(II). In addition, a reusability study showed that Cd-I-MA-co-AN can be recycled ten times and has high recovery in natural water samples.