DC magnetic field-assisted improvement of textile dye degradation efficiency with multi-capillary air bubble discharge plasma jet

Abstract

Axial DC magnetic field-assisted multi-capillary underwater air bubble discharge plasma jet has been used to study the productions of reactive oxygen species. Analyses of optical emission data revealed that the rotational (T_r) and vibrational temperatures (T_v) of plasma species slightly increased with magnetic field strength. The electron temperature (T_e) and density (n_e) increased almost linearly with magnetic field strength. T_e increased from 0.53 to 0.59 eV, whereas n_e increased from 1.03 × 10¹⁵ cm^-3 to 1.33 × 10¹⁵ cm^-3 for B = 0 to B = 374 mT, respectively. Analytical results from the plasma treated water provided that the electrical conductivity (EC), oxidative reduction potential (ORP), and the concentrations of O₃ and H₂ O₂ enhanced from 155 to 229 µS cm^-1, 141 to 17 mV, 1.34 to 1.92 mg L^-1, and 5.61 to 10.92 mg L^-1 due to the influence of axial DC magnetic field, while [Formula: see text] reduced from 5.10 to 3.93 for 30 min treatment of water with B = 0 and B = 374 mT, respectively. The model wastewater prepared with Remazol brilliant blue textile dye and the plasma treated wastewater studied by optical absorption spectrometer, Fourier transform infrared spectrometer, and gas chromatography mass spectrometer. The results show that the decolorization efficiency increased ~ 20% after 5 min treatment for the maximum B = 374 mT with respect to zero-magnetic field and, power consumption, and electrical energy cost reduced ~ 6.3% and ~ 4.5%, respectively, due to the maximum assisted axial DC magnetic field strength of 374 mT.

Keywords: DC magnetic field; Fourier transform infrared spectroscopy (FTIR); Gas chromatograph mass spectrometer (GC–MS); Reduction potential; Textile dye.