Selective adsorption and separation of BPA from aqueous solution using novel molecularly imprinted polymers based on kaolinite/Fe3O4 composites

Magnetic molecularly polymers (MMIPs) based on kaolinite/Fe3O4 composites were successfully synthesized for the selective adsorption and separation of bisphenol A (BPA) from aqueous solutions. During polymerization, the modified kaolinite/Fe3O4 (KLT/Fe3O4) not only was used as supporter but also functional monomer. The properties of MMIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, and thermogravimetric analysis (TGA) and so on. The SEM graphs showed that much of KLT/Fe3O4 was successfully coated by the imprinted layer, TGA analysis suggested the grafting yield of imprinted layer to KLT/Fe3O4 was 72.51 wt%. The effects of pH, initial BPA concentration, contact time and temperature of the medium on the adsorption were studied by the batch mode experiment. The equilibrium data was well described by the Langmuir isotherm model. The kinetics of adsorption followed the pseudo-second-order model and the rate constant decreased with the increase of temperature, indicating exothermal nature of adsorption process. For desorption studies, the highest desorption efficiency (95.75%) was obtained using methanol and acetic acid as eluting solution (v:v = 8:2). Moreover, the selectivity of MMIPs was further demonstrated through HPLC analysis of the stimulant water samples, the result showed that MMIPs could effectively recognize BPA in mixed solution. (C) 2011 Elsevier B.V. All rights reserved.