Synthesising nanocomposite Co2SnO4@rGO for peroximonosulphate activation in a hybrid ozonation system to effectively degrade cefalexin from wastewater

Abstract

This study successfully developed 2-Co₂SnO₄@rGO nanocomposites at various composite ratios of 2-Co₂SnO₄ and rGO using the sol-gel method. These nanocomposites were then used as heterogeneous catalysts to activate PMS in the heterogeneous catalytic oxidation of 2-Co₂SnO₄@rGO/PMS as well as the hybrid ozonation system O₃/2-Co₂SnO₄@rGO/PMS to degrade cefalexin (CFX). The physical-chemical characteristics of the fabricated catalysts were evaluated through nitrogen adsorption-deadsorption, SEM images, EDS mapping, and XRD. The catalytic activity of the nanocomposite was investigated in a degradation reaction of CFX from an aqueous solution. Besides this, CFX degradation kinetics were determined by fitting experimental data with a first-order model. The results showed that at the composite ratio of 2-Co₂SnO₄ and 1-rGO for CFX degradation had the highest efficiency reaching 95.07 and 99.07% for Co₂SnO₄@ rGO/PMS and O₃/Co₂SnO₄@rGO/PMS systems, respectively. The degradation of CFX in the O₃/Co₂SnO₄@rGO/ PMS system was higher than that of 2-Co₂SnO₄@rGO/PMS. The results were due to a remarkable increase in SBET in 2-Co₂SnO₄@1-rGO compared to both 2-Co₂SnO₄ and rGO, facilitating a catalytic reaction occurring on the catalyst’s surface. Moreover, the coupling between O₃ and 2-Co₂SnO₄@rGO/PMS generated a synergetic effect leading to the generation of more *SO₄^- and *OH radicals, which enhanced the CFX degradation rate in the hybrid ozonation system. These primary findings illustrated that the nanocomposite catalyst 2-2-Co₂SnO₄@1-rGO was feasible for the activation of PMS in hybrid ozonation to effectively degrade antibiotic residues from wastewater.