Efficient degradation of organophosphorus herbicide by free‐standing 3D reduced graphene oxide supported nFe₃O₄ catalytic‐activated persulfate

Abstract

BACKGROUND: Organophosphorus herbicides in water are an increasingly critical environmental problem. Given this challenge, a free-standing 3D reduced graphene oxide (GO) foam supporting Fe 3 O 4 nanoparticles (3D-rGO-Fe 3 O 4 ) was synthesized using GO as a precursor and applied as an efficient persulfate activator for glyphosate (GLY) degradation.RESULTS: The effects of Fe 3 O 4 mass, pH, oxidant dosage, temperature and common ions on GLY degradation were investigated in detail. Analytical techniques using scanning electron microscopy (SEM), Fourier transform infrared analysis (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that the 3D foam prevented aggregation of the Fe 3 O 4 nanoparticles by in situ uniform formation on GO nanosheets. The addition of Fe was vitally important for activation of the oxidation system. The results of batch-scale experiments illustrated that the GLY degradation efficiency reached 96.8% with initial GLY concentration 30 mg L −1 , graphene:Fe 3 O 4 mass ratio 1:7, solution pH 4 and persulfate mass 48 mg. High temperatures could significantly facilitate GLY degradation. Additionally, the 3D-rGO-Fe 3 O 4 material proved highly stable according to the replicated test results. Furthermore, EPR test results revealed that Na 2 S 2 O 8 catalytic activation by 3D-rGO-Fe 3 O 4 mainly produced •OH and SO 4 − •, and the predominant free radical was SO 4 − • in the current experiment. CONCLUSION:The results indicate that 3D-rGO-Fe 3 O 4 has good catalytic activity and stability, and, accordingly, has high application prospects for the remediation of organophosphorus herbicide-contaminated water.