Preparation, characterization, and adsorption performance of p-hydroxybenzoic acid imprinted polymer and selective catalysis of toluene to para-chlorotoluene



A p-hydroxybenzoic acid surface molecularly imprinted polymer (p-HB–SMIP) with silica microspheres as a supporting matrix was prepared by the adoption of the surface molecular imprinting technique with acrylamide (AM) as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, and azoisobutyronitrile as an initiator. The p-HB–SMIP was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetry. Interactions between the functional monomer and template were observed with UV–visible spectroscopy of the solutions of these components as well. The results indicate that a 1:2 molecular complex was formed between p-hydroxybenzoic acid (p-HB) and AM. A kinetic binding study showed that p-HB–SMIP reached saturation adsorption after about 1 h, and the pseudo-second-order model fitted the adsorption kinetics data. Static adsorption experiments revealed that the Freundlich equation fitted the adsorption isotherm data. The thermodynamics parameters (with positive values of enthalpy and entropy and negative values of Gibbs free energy) indicated that the binding system for p-HB–SMIP was endothermic and entropy was gained and was spontaneous. Selective experiments showed that p-HB–SMIP had a high affinity and excellent recognition selectivity for the template p-HB. p-HB–SMIP was further investigated by the catalysis of toluene to para-chlorotoluene. The catalytic reaction results showed that the conversion of toluene was 85.5% and the molar ratio of para-chlorotoluene to o-chorotoluene was 1.38; this was higher than that of traditional catalysts. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40118.