Novel Fe0 Embedded Alginate Beads and Coated with CuO-Fe3O4 as a Sustainable Catalyst for Photo-Fenton Degradation of Oxytetracycline in Wastewater

A novel catalyst made of zero-valent iron (Fe⁰) well dispersed and immobilized on alginate beads and coated using CuO-Fe₃O₄ (CuO-Fe₃O₄-Fe⁰/Abs) was designed and fabricated as a sustainable catalyst to degrade oxytetracycline using a heterogeneous photo-Fenton process. The CuO-Fe₃O₄ component was incorporated as a thin layer to cover the beads during the cross-linking reaction to allow immobilization of Fe⁰ inside the bead structure. Characterization analyses such as Fourier transform infrared spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy and X-ray photoelectron spectroscopy confirmed the successful immobilization of Fe⁰ on the thin layer of CuO-Fe₃O₄ on the beads. The performance test of the catalysts showed that they effectively removed OTC from water through the Fenton and photo-Fenton process at a wide range of pH values (pH 3–8) under visible irradiation. The optimum conditions to completely degrade 20 mg/L antibiotics were achieved at pH 3.0 in the presence of 200 mg/L (CuO-Fe₃O₄-Fe⁰/Abs) catalyst within 60 min of reaction time because of the synergic effect associated with Fe⁰ Fenton reaction in the presence of CuO-Fe₃O₄. These results proved the high performance of the catalyst for the OTC degradation in wastewater satisfactorily fits the pseudo-first-order kinetic model. The k value increases from 0.0476 for Cycle 1 to 0.0831 min⁻¹ for Cycle 4 to indicate that chemical reaction indeed played the predominant role in the OTC degradation. It also had high stability with the controlled release of Fe⁰ into the solution to enhance its catalytic activity.