Synergistic Removal of Diclofenac via Adsorption and Photocatalysis Using a Molecularly Imprinted Core–Shell Photocatalyst

In this work, a newly developed magnetic molecularly imprinted Fe₃O₄/SiO₂/TiO₂/MIP photocatalyst with diclofenac (DIC) as the template was prepared by microwave-assisted synthesis. The molecularly imprinted TiO₂ layer has specific cavities designed for the DIC target molecule (imprint), resulting in a synergistic effect of extraction by adsorption and photocatalysis. For reference, non-imprinted magnetic nanoparticles (Fe₃O₄/SiO₂/TiO₂) were prepared using the same procedure. The obtained particles were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), SEM-EDX, vibrating-sample magnetometry (VSM) and diffuse reflectance spectroscopy (DRS). Specific surface area, pore volume and pore size distribution were evaluated using Brunauer-Emmett-Teller (BET) adsorption-desorption isotherms. The synergistic effect of adsorption and photocatalysis as well as the kinetics and mechanism of DIC degradation using Fe₃O₄/SiO₂/TiO₂/MIP and Fe₃O₄/SiO₂/TiO₂ were determined and analysed. The adsorption efficiency of Fe₃O₄/SiO₂/TiO₂/MIP for DIC (10 mg dm^-3) was around 86% after 60 min. The DIC (10 mg dm^-3) removal efficiency of Fe₃O₄/SiO₂/TiO₂/MIP was around 80% after 30 min adsorption and 120 min of reaction under both UV-A- and solar-simulated light irradiation.