Selective recognition of 2,4-dichlorophenol from aqueous solution by uniformly sized molecularly imprinted microspheres with β-cyclodextrin/attapulgite composites as support

In this study, uniformly sized molecularly imprinted microspheres (MIP) using beta-cyclodextrin/attapulgite composites as support were prepared for recognitive adsorption of 2,4-dichlorophenol (2,4-DCP) from aqueous solution. Characterization of MIP were achieved by FT-IR spectra, SEM micrographs, nitrogen adsorption-desorption analysis, EDX measurement and elemental analysis. Equilibrium data, at various temperatures, were described by the Langmuir. Freundlich and Dubinin-Radushkevich isotherm models. The thermodynamics parameters (positive values of Delta H degrees and Delta S degrees, negative values of Delta G degrees) indicated that binding system for MIP was endothermic, entropy gained and spontaneous. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model, intraparticle diffusion equation, initial adsorption rate, half-adsorption time and activation energy. A diffusion-controlled process as the essential adsorption rate-controlling step was also proposed. MIP could be reused four times without significant loss in adsorption capacity. The selectivity of MIP also demonstrated higher affinity for target 2,4-DCP over competitive phenolic compounds than that of non-imprinted polymers (NIP). Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.