Metronidazole elimination from wastewater through photo-Fenton process using green-synthesized alginate-based hydrogel coated bimetallic iron-copper nanocomposite beads as a reusable heterogeneous catalyst

The photo-Fenton process on heterogeneous nano-catalyst was applied for the metronidazole elimination from a wastewater. The iron-copper nano-catalyst was synthesized through the green synthesis and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX). The response surface methodology (RSM) based on Box-Behnken design (BBD) was used to investigate and optimize five significant variables (including catalyst loading, initial pH, reaction time, metronidazole, and H2O2 concentration) through forty-six experiments. A quadratic model (with P-value < 0.0001 and R-2 = 93.5) was properly derived. The optimum conditions were at 44.7 mg/L of catalyst, 3.5 pH, 85 min of reaction time, 10 mg/L of metronidazole and 33.17 mmol/L of H2O2. 95.0% of metronidazole was experimentally eliminated under the optimum conditions which agreed well with the model. Furthermore, it was concluded that the selected magnetic catalyst can easily be recovered by magnetic separation or passing through a suitable filter.