Novel magnetic nanocomposite Fe3O4@CS@PHMG as an effective and recyclable antimicrobial material for hospital wastewater disinfection

Abstract

Hospital wastewater (HWW) is a major pollutant that presents significant risks to both environmental and human health. In this study, we developed a novel, inexpensive and highly antibacterial magnetic nanocomposite composed of Fe₃O₄ nanoparticles synthesised from spent pickling liquors, coated with chitosan and then integrated with polyhexamethylene guanidine hydrochloride (Fe₃O₄@CS@PHMG) using sodium tripolyphosphate (TPP) as a crosslinking agent. The obtained results revealed that the synthesised nanocomposite exhibited high antibacterial activity against E. coli and S. aureus. At a relatively low nanocomposite dosage of 2 μg mL⁻¹, it effectively eliminated all E. coli at a concentration of ∼10⁵ CFU mL⁻¹ within one min. For S. aureus, a higher dosage of 5 μg mL⁻¹ and a longer time of 5 min were required for complete elimination. In real HWW treatment tests, 99.4% of E. coli and 95.8% of total coliforms were eliminated at a nanocomposite dosage of 10 μg mL⁻¹. At 30 μg mL⁻¹, the nanocomposite completely removed all E. coli.