Functionalization of Molecularly Imprinted Polymer Microspheres for the Highly Selective Removal of Contaminants from Aqueous Solutions and the Analysis of Food-Grade Fish Samples

Abstract

The proliferation of pollution in aquatic environments has become a growing concernand calls for the development of novel adsorbents capable of selectively removing notorious andrecalcitrant pollutants from these ecosystems. Herein, a general strategy was developed for thesynthesis and functionalization of molecularly imprinted polymer microspheres (MIPs) that couldbe optimized to possess a significant adsorption selectivity to an organic pollutant in aqueousmedia, in addition to a high adsorption capacity. Considering that the molecular imprinting alonewas far from satisfactory to produce a high-performance MIPs-based adsorbent, further structuralengineering and surface functionalization were performed in this study. Although the more carboxylgroups on the surfaces of the MIPs enhanced the adsorption rate and capacity toward an organicpollutant through electrostatic interactions, they did not strengthen the adsorption selectivity in aproportional manner. Through a systematic study, the optimized sample exhibiting both impressiveselectivity and capacity for the adsorption of the organic pollutant was found to possess a smallparticle size, a high specific surface area, a large total pore volume, and an appropriate amount ofsurface carboxyl groups. While the pseudo-second-order kinetic model was found to better describethe process of the adsorption onto the surface of MIPs as compared to the pseudo-first-order kineticmodel, neither Langmuir nor Freundlich isothermal model could be used to well fit the isothermaladsorption data. Increased temperature facilitated the adsorption of the organic pollutant onto theMIPs, as an endothermic process. Furthermore, the optimized MIPs were also successfully employedas a stationary phase for the fabrication of a molecularly imprinted solid phase extraction column,with which purchased food-grade fish samples were effectively examined.

Keywords

• molecular imprinting
• molecular recognition
• emulsion polymerization
• MISPE column
• stationary phases
• adsorption selectivity