Study on the nonylphenol removal from aqueous solution using magnetic molecularly imprinted polymers based on fly-ash-cenospheres

Fly-ash-cenospheres/Fe3O4 magnetic particles (MFACs) were firstly achieved by co-precipitation technique. After endowing with reactive vinyl groups onto the surface of MFACs, magnetic molecularly imprinted polymers (MMIPs) based on the modified MFACs were further prepared by suspension polymerization. The as-prepared MMIPs were charcterized, and the results indicated that spherical MMIPs exhibited superparamagnetic property (M-s = 20.99 emu g(-1)), magnetic stability (at the pH = 6.0), thermal stability (<100 degrees C) and composed of imprinted layer. Batch mode adsorption experiments were carried out to investigate the specific adsorption equilibrium, kinetics and selective recognition. The initial pH = 6.0 was the optimal condition, and the hydrogen bond interaction may be the main recognition mechanism. The kinetic properties of MMIPs were well described by the pseudo-second-order equation, indicating chemical process could be the rate-limiting step in the adsorption process for NP. The adsorption equilibrium of NP using MMIPs was better modelled by the Langmuir isotherm equation, and the monolayer adsorption capacity of MMIPs at 298 K was 434.8 mg g(-1). The selectivity results showed that MMIPs had the specific adsorption for NP molecules, and the recognition process may be related to the size, structure and functional group of the template molecules. (C) 2013 Elsevier B.V. All rights reserved.