A novel water disinfection method via cuprous ion generation in a copper ferrite/sulfite system and associated mechanism

Aqueous pathogenic microorganisms pose a significant risk to public health, but conventional disinfection methods present numerous drawbacks. By employing bactericidal tests, radical quenching experiments, and quantitative toxicogenomic assay, this study aimed to evaluate the effectiveness and associated cellular mech-anism of a novel disinfection process combining recyclable copper ferrite (CuFe2O4) nanoparticles with sulfite. At the optimal CuFe2O4 (800 mg/L) and sulfite (4 mM) concentrations determined, the CuFe2O4/sulfite system inactivated 4.65-log (>99.99 %) of Escherichia coli cells at an initial concentration of 10(8) colony-forming units (CFU)/mL in 3 h. Meanwhile, the E. coli cells at the initial concentration of 10(4) -10(6) CFU/mL were 100 % inactivated within 1-2 h. Cuprous ions (Cu(I)) rather than sulfate radicals (SO4 center dot-) played the dominant role in the inactivation process, by breaking the cell membrane, damaging intracellular components (such as adenosine triphosphate and nicotinamide adenine dinucleotide), and stimulating increased reactive oxygen species production. Correspondingly, the toxicogenomics-based toxicity assessment indicated the induction of oxidative damage to exposed cells as a dominant molecular-level disinfection mechanism of the CuFe2O4/sulfite system. Moreover, the CuFe2O4/sulfite system exhibited comparable inactivation efficiency against three other bacterial species, while gram-positive strains (Staphylococcus aureus and Bacillus subtilis) were more susceptible to this system than gram-negative ones (Pseudomonas aeruginosa and E. coli). The magnetic recyclable CuFe2O4/sulfite system is a promising water disinfection method owing to its efficacy, convenience, and environmental sustainability.