Accelerated degradation of groundwater-containing malathion using persulfate activated magnetic Fe3O4/graphene oxide nanocomposite for advanced water treatment

Abstract

Malathion (MT) is a widely used organophosphate insecticide with a broad spectrum. MT residues in the environment even at low concentrations can have adverse effects on humans, plants, animals, and ecosystems. In this study aimed to investigate the MT degradation yield from groundwater using persulfate activated magnetic Fe3O4/graphene oxide nanocomposite (PS/Fe3O4-GO MNCs). Thus, the effects of MT concentration, the dosage of PS and Fe3O4-GO MNCs, pH value along with reaction time were investigated and further optimized applying Response Surface Method (RSM). This model equation showed a sufficient match with the measured results from the experimental data with the correlation coefficient (R2) of 0.9819 according to the analysis of variance. For the optimal yield, MT concentration of 3.7 mg/L, PS of 2.25 mM, Fe3O4-GO MNCs dosage of 225 mg/L, reaction time of 22 min and pH of 4 were obtained. Moreover, for MT degradation, the estimated optimal degradation efficiency was 96.5 %. Furthermore, a distinct synergistic effect was observed upon the usage of Fe3O4-GO MNCs for PS activation. The MT degradation rate is generally characterized by a pseudo-first-order kinetic model. Besides, experiments with radical scavengers revealed that both OH∙ and SO4-∙radicals had significant functions in MT degradation yields, with sulphate radicals being the dominant species. Conclusively, results revealed that the PS/Fe3O4-GO MNCs degradation process is an effective method for remediating waters that have been polluted with MT and related pesticides.