Degradation of oxytetracycline in wastewater based on activated persulfate by biosynthesized iron oxide nanoparticles and carbon nanotube-modified biochar

Abstract

In this study, a green and safe modified biochar (OBC) was successfully prepared by combining biosynthesized iron oxide nanoparticles with carbon nanotubes to activate peroxydisulfate for oxytetracycline (OTC) degradation. The OBC exhibited excellent catalytic performance and 91 % OTC was removed based on optimized preparation and operating conditions (initial concentration of 50 mg L−1). Multiple quenching experiments and free radical assays revealed that singlet oxygen (1O2) was the sole active species. Besides, the pathway of 1O2 production was inferred by comprehensive characterization analysis (SEM−EDS, XRD, FTIR, XPS). The OTC removal was mainly attributed to the non-radical pathway consisting of OBC adsorption, 1O2 oxidation, and direct electron transfer combined with the electrochemical measurement results. Meanwhile, the stability of the catalytic system was determined by adjusting the solution parameters. The Liquid Chromatography Mass Spectrometer (LC-MS) showed that OTC was converted to small molecules by dehydration, amino, methyl shedding, or dehydroxylation. This clean, reliable, and energy-efficient activation method will provide insight into the effective treatment of antibiotics from wastewater.