Degradation of methylene blue in liquid using high-voltage pulsed discharge plasma synergizing iron-based catalyst-activated persulfate

Abstract

In this work, high-voltage pulsed Ar gas–liquid discharge synergizing iron-based catalyst-activated persulfate (PS) was employed to degrade methylene blue (MB) in water. The catalytic performances of two types of iron-based catalysts, namely the homogeneous catalyst Fe2+ and the heterogeneous catalyst nano-Fe3O4, were compared. Correspondingly, the plasma gas temperature and excited species were calculated and diagnosed using optical emission spectra. It was found that the introduced plasma process significantly enhanced the degradation efficiency of MB by the PS/Fe2+ and the PS/Fe3O4 systems. After 20 min of treatment, the MB degradation efficiency reaches 97.5% and 83.1% in the hybrid plasma/PS/Fe2+ and plasma/PS/Fe3O4 systems, respectively, which is 37.9% and 35.6% higher than that in the PS/Fe2+ and PS/Fe3O4 systems. The synergistic mechanism and key reactive species responsible for MB degradation in hybrid plasma/PS/Fe2+ and plasma/PS/Fe3O4 were explored using the addition of radical scavengers and control experiments under various conditions. The homogeneous catalyst Fe2+ exhibits better activation performance in PS and plasma than that of the heterogeneous catalyst nano-Fe3O4.

Insights into reactivity and bactericidal effects of water activated by He and Ar plasma jets

“…The OH peak should derive from the small amount of H 2 O vapor excited in the plasma discharge since plasma directly contacts the water surface. [ 16 ] On the other hand, the peaks of O(3p 5p ) and N 2 + (B) are only detected in the spectrum of the He plasma jet. N 2 + (B) could be attributed to the Penning effect between metastable He species and N 2 , and O(3p 5p ) is mainly from the oxygen in air colliding with excited He species.…”

“…The peaks of OH(A) at the wavelength of 309 and 616 nm and the excited nitrogen of N 2 (C) are all detected in the spectrum of the He and Ar plasma jets, while the intensity peaks of OH(A) and N 2 (C) in the Ar plasma jet are stronger than that in the He plasma jet, which indicates the higher concentrations The OH peak should derive from the small amount of H 2 O vapor excited in the plasma discharge since plasma directly contacts the water surface. [16] On the other hand, the peaks of O(3p 5p ) and N 2 + (B) are only detected in the spectrum of the He plasma jet. N 2 + (B) could be attributed to the Penning effect between metastable He species and N 2 , and O(3p 5p ) is mainly from the oxygen in air colliding with excited He species.…”

Dynamics of NO, N2O, and ONOOH in atmospheric-pressure air dielectric barrier discharge: decoupling energy density and gas temperature effects varying with discharge voltage

“…Subsequently, MATLAB was used to calculate the residuals of the measured and calculated spectra at different wavelengths. The temperature of the calculated spectra corresponding to the minimum sum of the residuals can be expressed as the plasma gas temperature T g [32,48]. A schematic diagram for obtaining the gas temperature by comparing the experimentally measured and theoretically calculated spectra of N 2 (C-B, 0-0) is shown in figure 1(d).…”

Generation of High-Density Pulsed Gas–Liquid Discharge Plasma Using Floating Electrode Configuration at Atmospheric Pressure

“…Atmospheric pressure (AP) gas-liquid discharge plasma has been actively investigated for its promising application prospects in water purification [1][2][3], biomedicine [4][5][6], and materials processing [7][8][9]. However, random micro discharge channels occur easily which can lead to non-directed energy distribution leading to serious issues and adversely affecting industrial applications.…”