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

Abstract

Highly selective submicrosized molecularly imprinted polymer (SMIP_MP) for methylparaben (MP) was synthesized by molecular imprinting technique with a sol–gel process on silica submicroparticles. The prepared SMIP_MP was characterized by FT-IR, SEM, TG, and N₂ adsorption–desorption techniques. Compared with microsized methylparaben imprinted polymer (MMIP_MP) adsorbent, SMIP_MP 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 SMIP_MP was 32.68 mg g^–1, and the adsorption equilibrium could be reached in 40 min. The SMIP_MP adsorbent could be used at least 5 times without significant loss in adsorption capacity. Compared with submicrosized nonimprinted polymer (SNIP), SMIP_MP indicated excellent recognition and binding affinity toward MP molecules, whose selectivity coefficients for MP relative to methyl salicylate (MS) and <i>p-</i>hydroxybenzoic acid (<i>p-</i>HB) were 5.664 and 6.129, respectively. The mechanism for static adsorption of MP onto SMIP_MP 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 SMIP_MP and SNIP, which showed that the linear and nonlinear methods were both suitable to predict the breakthrough curves but the nonlinear method was better