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

Abstract

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.