Facile preparation of molecular-imprinted polymers for selective extraction of theophylline molecular from aqueous solution

Abstract

• THP-MIPs prepared by MIT were used for selective extraction of THP. • THP-MIPs had a good thermal stability. • THP-MIPs exhibited a high recognition property in the presence of competing molecules. • THP-MIPs showed a good reusability after seven-time adsorption-desorption cycles. The selective extraction of trace amounts in wastewater is necessary for the detection of water targets. In this study, theophylline-molecularly imprinted polymers (THP-MIPs) were prepared using molecular imprinting technique (MIT) for selective extraction of theophylline (THP) from wastewater. Modified silica, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) worked as functional matrix, monomers and cross-linking agents for THP-MIPs preparation. Influences of MAA dosage, cross-linking reagent dosage and cross-linking time on the adsorption capacity of synthesized THP-MIPs were analyzed. The Fourier-transform infrared (FT-IR) characterization analysis of THP-MIPs indicated the polymer was successfully synthesized. While, the thermodynamic analysis indicated the THP-MIPs had a good thermal stability below 220 °C and the THP-MIPs with the largest negative charge and the strongest electrostatic interaction at pH of 7.0. THP-MIPs reached a maximum adsorption capacity of 14.55 mg g −1 when the pH of the solution was 7.0 and the initial concentration of THP was 200 mg L −1 . The adsorption process of THP-MIPs was described using Freundlich isotherms and quasi-second-order kinetic models. The results indicated the synthesized THP-MIPs had a good selectivity and reusability in the presence of competing molecules.