Synergistic sterilization effect of microwave-excited nonthermal Ar plasma, H₂O₂, H₂O and TiO₂, and a global modeling of the interactions

Abstract

A microwave-excited atmospheric-pressure plasma jet (uAPPJ) exhibited a synergistic sterilization effect when combined with hydrogen peroxide (H 2 O 2 ), distilled water (DW) and titanium dioxide (TiO 2 ) photocatalysis. The sterilization efficacy of H 2 O 2 -uAPPJ increased as the H 2 O 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 2 O 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.

Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

“…Thence, the bulk plasma density n bulk can be calculated 8:3 Â 10 20 m -3 approximately. It should be mentioned that although this density value is consistent with previous studies reported from the similar lowerpower argon microwave plasma jets driven by continues microwave power in ambient air, [3][4][5][6][7][8][9][10][11][12][13][14][15][16]32 the actual plasma density of the pulsed plasma jet is lower than this value, due to the average power absorbed by the electrons lower largely in pulsed discharge with the same peak power amplitude.…”

“…(18) and the operation of plasma fluid subloop (Eqs. (6) and (7)) starts. After 992 iterations, the converged solution of the electron density and electron temperature is arrived at.…”

“…1,2 One type of them, named low-power microwave-driven atmospheric plasma jet, is generated based on microwave resonant effect, which have several advantages over low-frequency plasmas, such as higher density of electron and reactive species, lower plasma plume temperature, lower applied power, and longer electrode lifetime. [3][4][5][6][7] Especially for several applications, such as medical instrument sterilization, metal surface nitriding, and high-velocity fuel ignition and combustion, atmospheric microwave plasma devices have shown its potential advantages in industrial applications. [8][9][10][11] There are four types of low-power microwave resonators: coaxial transmission line resonators (CTLR), 3 microstrip line resonators, 4 surfatron launchers, 12 and surface-wave plasma jets, [13][14][15] which are with different characteristics and thereafter are constructed for satisfying different application demands.…”

Characterization and Effects of Ar/Air Microwave Plasma on Wound Healing

“…Non‐equilibrium atmospheric pressure plasma jets (APPJs) have been attractive for many biomedical applications, ranging from cancer cell treatment, sterilization, wound healing, coagulation, and tooth whitening . Compared with the low‐pressure plasmas, APPJs have advantages because they can be operated without a bulky vacuum pump with relatively low power requirements .…”

Catalyst Effect on Degradation of Organism by Nanoseconds Pulsed Discharge in Gas-Liquid Mixture

“…The increment rate (≈3.9 µM/min) was more than twice larger than that (≈1.5 µM/min) of UV/TiO 2 [11] with smaller amount of powder. It is considered the synergistic effect of plasma and TiO 2 , as observed in the research of plasma sterilization [12]. Plasma also can activate the TiO 2 and the electric field can help the separation process of photo-generated carriers to enhance the catalytic effect [13].…”