Biosynthesis of iron oxide nanoparticles for the degradation of methylene blue dye, sulfisoxazole antibiotic and removal of bacteria from real water

Water pollution that is caused by dyes, bacteria and antibiotics, has resulted in a threat to living organisms, animals and humans, hence there is a need to synthesize multifunctional materials that can be used for the degradation of various pollutants. The aim of this study was to synthesize Iron oxide (Fe₃O₄) NPs and test this material for photocatalytic degradation and antibacterial activity. The synthesis of Iron oxide (Fe₃O₄) NPs was conducted using M. burkeana extract and characterised using UV-vis, XRD, BET, SEM, EDS and TGA. The material was then tested for its photocatalytic and antibacterial efficiency against methylene blue dye, antibiotic sulfisoxazole and E. coli and S. aureus bacterial strains. XRD confirmed the formation of Fe₃O₄ NPs. UV-vis gave optical information whereby an excitation at 320 nm and a bandgap of 3.74 eV was noted. The deposition of the phytochemicals onto the Fe₃O₄ NPs was demonstrated using FTIR. From the surface analysis, the morphology of the synthesized NPs was found to be rod like and mesoporous. Upon testing for methylene blue degradation, the Fe₃O₄ NPs were more potent under basic conditions (pH 12) and the O₂ radicals were found to be the species responsible for the degradation. Against sulfisoxazole, a 60% degradation was observed. Lastly, when testing these materials against bacterial strains found in tap, pond, river and sewage water, they were potent in particular against gram positive strains. These results show that at optimum conditions, these materials are able to degrade various pollutants in wastewater.