Synergistic sterilization effect of microwave-excited nonthermal Ar plasma, H_2O_2, H_2O and TiO_2, and a global modeling of the interactions

摘要

A microwave-excited atmospheric-pressure plasma jet (uAPPJ) exhibited a synergistic sterilization effect when combined with hydrogen peroxide (H_2O_2), distilled water (DW) and titanium dioxide (TiO_2) photocatalysis. The sterilization efficacy of H_2O_2–uAPPJ increased as the H_2O_2 concentration increased. The addition of TiO_2 also remarkably increased the sterilization efficacy. To find the main factor for the sterilization effect, optical emission spectra and the degradation rate of a methylene blue solution were measured. Numerical analysis, a newly developed global modeling, was also conducted to discover the mechanisms. Both experimental measurements and global modeling results suggested that combinations of H_2O_2, DW and TiO_2 increased the generation of hydroxyl radicals (·OH), which are known to be strong bactericidal agents. It was revealed that charged species, especially electrons, have a dominant role in the increase of ·OH.