Preparation of novel semi-covalent molecularly imprinted polymer for highly improved adsorption performance of tetracycline in aqueous medium

Abstract

In the present study, a novel tetracycline-imprinted polymer for tetracycline (TC) adsorption in an aqueous medium was synthesized using a semi-covalent imprinting method for the first time. In this approach, the template-monomer complex was synthesized by the reaction of 3-isopropenyl-α,α-dimethylbenzyl isocyanate (IPDMBI) as the functional monomer and TC as a template, forming a thermally reversible urethane bond (covalent bond). The polymer was characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), nitrogen adsorption/desorption measurements, and determination of point zero charge (PCZ). The equilibrium time of TC onto MIP was reached in 15 min, which was described by the non-linear pseud second-order kinetic model. Adsorption isotherm was described as a dual-site Langmuir-Freundlich model and the maximum adsorption capacity, determined at pH 5.0, was found to be 76.74 mg g⁻¹ for MIP, exhibiting higher adsorption capacity when compared with other adsorbent materials previously reported in the literature for TC. Based on the increment relative selectivity coefficient the MIP showed higher selectivity towards TC and some structurally similar compounds belonging to the tetracyclines family (oxytetracycline and chlorotetracycline), when compared with NIP (non-imprinted polymer). The obtained outcomes in terms of selectivity, maximum adsorption capacity, and fast kinetic make this imprinted polymer an outstanding material for future application in molecularly imprinted solid phase extraction for analytical purposes.