Virus-induced redox cycling in Fe(II)/peracetic acid systems: dual roles as reactant and catalytic promoter

The conventional Fenton system suffers from critical limitations, including significant pH dependence and inefficient iron cycling. This study innovatively developed a Fe(II)/peracetic acid (PAA) hybrid disinfection system, systematically investigating its viral inactivation performance and molecular mechanisms under near-neutral conditions. The results demonstrated that this system achieved above 5 logs viral inactivation (under 50 μM Fe(II)/50 μM PAA, pH 3-7) through a unique three-stage mechanism. This mechanism included radical burst, self-catalytic iron cycling and coordination environment reconstruction, inducing deformation and conformational changes in capsid protein. Notably, non-radical species (Fe(IV) and ¹O₂) consistently accounted for over 50% of total inactivation efficiency. Steady-state concentration calculations, cumulative reactive species quantification, and 30% Fe(II) regeneration observed within 30 min all jointly confirmed the virus enhanced Fe(II)/Fe(III) cycling. Study on the mechanism revealed that the components of virus capsid performed dual roles: sulfur-containing amino acids (e.g., cysteine) acted as oxidation targets, while aromatic residues (e.g., phenylalanine) served as catalytic sites. Through strong coordination interactions via Fe(III)-π intermediates, an efficient Fe(II)/Fe(III) coupling cycle was achieved. This system reveals a novel mechanism whereby the virus itself catalyzes and enhances iron cycling. In practical applications, it is expected to reduce chemical reagent usage and decrease iron sludge production, offering a new pathway for developing cost-effective green disinfection technologies.