Synthesis and characterization of the molecularly imprinted mesoporous silica based on the self-assembly technique for selective recognition of lomefloxacin in aqueous solution

Abstract

Based on double-imprinting (surfactant and lomefloxacin templates) concept and self-assembly technique, a new molecularly imprinted mesoporous silica (MIP-MS) was prepared to understand and characterize the mechanism of fast binding and selective recognition of lomefloxacin (LOM) by the adsorption isotherms model, the adsorption kinetic models, and the competitive adsorption. The MIP-MS was prepared by using LOM and surfactant micelles as the templates formed through self-hydrolyzed, self-condensed, and co-condensation of tetraethoxysilane and methyltriethoxysilane in alkaline media, and with the covalently anchored organic groups in the mesoporous silica matrix. Both the molecularly imprinted polymer (MIP) and non-imprinted mesoporous polymer (NIP) were prepared for comparison. The surface area, pore size and pore volume of the MIP-MS are 270 m2 g−1, 4.42 nm and 0.28 cm3 g−1, respectively. The kinetics studies showed that the pseudo-second-order model was consistent with the kinetic data of the MIP-MS with the fast binding templates (the 95 % uptake of LOM within 10 min). The equilibrium data, at various temperatures, were described successfully by the Langmuir and Freundlich isotherm models. The Freundlich model was found to fit the experiment data well. The thermodynamics parameters (positive values of ΔS, negative values of ΔH and ΔG) indicated that the binding system for the MIP-MS was entropy-gained, exothermic, and the spontaneous adsorptive forces were stronger on MIP-MS than on NIP and MIP. The MIP-MS showed fast binding, higher affinity, and selectivity for the template of LOM compared with the NIP and MIP.