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

Van Long Nguyen, Minh Thanh Le, Lan Huong Nguyen^*

Ho Chi Minh city University of Food Industry

Received 16 September 2022; accepted 20 November 2022

Abstract:

This study successfully developed Co₂SnO₄@rGO nanocomposites at various composite ratios of 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 Co₂SnO₄@rGO/PMS as well as the hybrid ozonation system O₃/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 Co₂SnO₄@rGO/PMS. The results were due to a remarkable increase in S_BET in 2-Co₂SnO₄@1-rGO compared to both Co₂SnO₄ and rGO, facilitating a catalytic reaction occurring on the catalyst’s surface. Moreover, the coupling between O₃ and 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-Co₂SnO₄@1-rGO was feasible for the activation of PMS in hybrid ozonation to effectively degrade antibiotic residues from wastewater.

Keywords: cephalexin, Co₂SnO₄@rGO, hybrid ozonation, O₃, PMS, synthesis.

Classification number: 3.5