Synthesis of superparamagnetic Fe3O4-graphene oxide-based material for the photodegradation of clonazepam

Abstract

The global concern over water pollution caused by contaminants of emerging concern has been the subject of several studies due to the complexity of treatment. Here, the synthesis of a graphene oxide-based magnetic material (GO@Fe₃O₄) produced according to a modified Hummers' method followed by a hydrothermal reaction was proposed; then, its application as a photocatalyst in clonazepam photo-Fenton degradation was investigated. Several characterization analyses were performed to analyze the structure, functionalization and magnetic properties of the composite. A 2³ factorial design was used for the optimization procedure to investigate the effect of [H₂O₂], GO@Fe₃O₄ dose and pH on clonazepam degradation. Adsorption experiments demonstrated that GO@Fe₃O₄ could not adsorb clonazepam. Photo-Fenton kinetics showed that total degradation of clonazepam was achieved within 5 min, and the experimental data were better fitted to the PFO model. A comparative study of clonazepam degradation by different processes highlighted that the heterogeneous photo-Fenton process was more efficient than homogeneous processes. The radical scavenging test showed that $O_2^{·-}$ was the main active free radical in the degradation reaction, followed by hydroxyl radicals (^•OH) and holes (h⁺) in the valence layer; accordingly, a mechanism of degradation was proposed to describe the process.