Analysis, design, and comprehensive evaluation of magnetic molecularly imprinted polymer for selective diclofenac removal

Diclofenac (DCF), a nonsteroidal anti-inflammatory drug (NSAID), is frequently detected in pharmaceuticals, hospitals, and domestic wastewater. It poses environmental and health risks due to its persistence in wastewater, with only ۳۰–۷۰% removed during treatment. Adsorption is a promising alternative for DCF removal due to its simplicity, efficiency, and cost-effectiveness. In this study, Magnetic Molecularly Imprinted Polymer (MMIP) was synthesized using DCF as a template, ۴-vinylpyridine as the monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and Fe₃O₄ as the magnetic core to enhance separation efficiency. Characterization confirmed successful synthesis, with XRD showing Fe₃O₄’s cubic spinel structure and FTIR identifying functional groups specific to Fe₃O₄ and DCF. SEM-EDS and TEM revealed spherical particles with embedded Fe₃O₄, and VSM indicated reduced magnetic saturation of MMIP after template removal. Adsorption studies demonstrated MMIP’s higher capacity (۸۳.۵۴ mg g-۱) compared to Magnetic Non-Imprinted Polymers (MNIP, ۶۹.۱۹ mg g-۱) under optimal conditions (pH ۵, ۳.۰ g L-۱ dosage), following the Sips isotherm model and pseudo-second-order kinetics. The method exhibited a linear range of ۴–۲۰ mg L⁻¹, a recovery of ۸۵–۱۰۵%, and an RSD <۳%, confirming the reproducibility and reliability of the adsorption performance by UV-Visible spectrophotometer. Thermodynamic analysis revealed the process was endothermic and spontaneous, while intra-particle diffusion was identified as the rate-limiting step. MMIP exhibited high selectivity for DCF over ibuprofen and naproxen and maintained stable adsorption efficiency over five reuse cycles. These results establish MMIP as a selective, reusable, and efficient adsorbent for DCF removal in medical wastewater treatment systems.

Keywords:

Diclofenac , UV-Visible Spectrophotometer , Molecularly imprinted polymer , Magnetite , Adsorption performance , Characterization