Fabrication and characterization of pectin-graphene oxide-magnesium ferrite-zinc oxide nanocomposite for photocatalytic degradation of diclofenac in an aqueous solution under visible light irradiation

Wastewater containing pharmaceutical contaminants has become a critical environmental concern due to rising population and drug consumption caused by increased life expectancy. Diclofenac (DCF) is one of the most applicable drugs for veterinary and human health purposes, polluting surface waters in different ways. This work aims to synthesize a novel pectin-graphene oxide (GO)-magnesium ferrite (MgFe₂O₄)-zinc oxide (ZnO) nanocomposite (PGMZ) for photocatalytic degradation of DCF in an aquatic environment under visible light irradiation. The single and synthesized nanocomposites were characterized by several analyses, confirming the successful synthesis of the nanocomposite. Effects of four operation conditions, including nanocomposite dosage (1-1.25 g/L), nanocomposite type, initial contaminant concentration (35-55 mg/L), and solution pH (3-11), were investigated on the degradation performance. From the kinetic study, the effect of mixing two composites, i.e., synergy percentage, was 38.7% when ZnO-MgFe₂O₄ particles were added to the GO-pectin structure. By examining the effect of different free radical enhancers and scavenging compounds on the DCF photodegradation, the most influential scavenging components were in the following order; NaCl > Na₂CO₃ > Na₂SO₄, while K₂S₂O₈ was a better enhancer than H₂O₂ at their optimal concentration. Finally, the PGMZ photocatalyst was reused six times with a reduction of about 20% in its removal efficiency, indicating excellent reusability and stability.