The fabrication of molecularly imprinted polymer microspheres via Pickering emulsion polymerization stabilized with novel ferric hydroxide colloid

Abstract

In this paper, the ferric hydroxide colloid was prepared firstly, which was found suitable for the stabilizer of Pickering emulsion because of proper hydrophilicity. Then, molecularly imprinted polymers (MIPs) microspheres were synthesized by means of facile Pickering emulsion polymerization using ferric hydroxide colloid as emulsifier. In the synthesis process, hydrophilic methacrylic acid was used for the functional monomer, and ethylene glycol dimethacrylate served as the crosslinking agent. Bisphenol A (BPA), a typical endocrine-disrupting chemical, was used for the template molecules. The whole synthesis was based on the hydrogen bonds interaction between the functional monomer and template molecule. The ferric hydroxide colloid could be removed from the surface of microspheres by gentle washing. The morphology of obtained MIPs microspheres were assessed through the optical microscope and field emission scanning electron microscope, respectively. The results suggested that the MIPs appeared the regular spherical form with relatively wide size distribution, whose diameter varied from 10 to 60 μm. The adsorptive property was studied detailedly through a series of rebinding experiments. The research showed that MIPs have fast binding kinetics, whose rebinding equilibrium in tested concentration could be achieved within 60 min, and the rebinding capacity in 0.3 mmol L−1 of BPA initial solution is 8.19 μmol g−1. Additionally, the binding capacities of MIPs were larger than that of non-imprinted polymers in the batch equilibrium binding experiments. The binding selectivity was investigated with 4, 4′-biphenol and hydroquinone, which played the role of the structurally similar compounds of template molecules. The result showed that the MIPs were highly selective for BPA, and the imprinting factor was calculated to be 1.63. Reusability experiment indicates that our prepared MIPs have good mechanical stability and could be reused at least 5 times. The MIPs microspheres would be valuable in the field of environmental protection.