Selective Adsorption of Methylparaben by Submicrosized Molecularly Imprinted Polymer: Batch and Dynamic Flow Mode Studies

Highly selective submicrosized molecularly imprinted polymer (SMIPMP) for methylparaben (MP) was synthesized by molecular imprinting technique with a sol-gel process on silica submicroparticles. The prepared SMIPMP was characterized by FT-IR, SEM, TG, and N-2 adsorption-desorption techniques. Compared with microsized methylparaben imprinted polymer (MMIPMP) adsorbent, SMIPMP adsorbent with small particle size and high specific surface area showed faster adsorption rate and stronger adsorption capacity for MP. The maximum static adsorption capacity for MP of SMIPMP was 32.68 mg g(-1), and the adsorption equilibrium could be reached in 40 min. The SMIPMP adsorbent could be used at least 5 times without significant loss in adsorption capacity. Compared with submicrosized nonimprinted polymer (SNIP), SMIPMP indicated excellent recognition and binding affinity toward MP molecules, whose selectivity coefficients for MP relative to m ethyl salicylate (MS) and p-hydroxybenzoic acid (P-HB) were 5.664 and 6.129, respectively. The mechanism for static adsorption of MP onto SMIPMP was found to follow Freundlich, Redlich-Peterson isotherm, and pseudo-second-order model. Thomas' model was applied in the quantitative description and parametrization of the dynamic adsorption of MP to SMIPMP and SNIP, which showed that the linear and nonlinear methods were both suitable to predict the breakthrough curves but the nonlinear method was better.