Textile wastewater treatment by underwater parallel-multi-tube air discharge plasma jet

Abstract

Textile wastewaters (WW) as released from textile industries damage aquatic environment and thereby create threat to plants and animals. To overcome the problems associated with wastewaters, the plasma technology can be an alternative approach for the reduction of effluents dissolved in textile WWs. In this present study, the degradation of textile dye model WWs is carried out using underwater parallel-multi-tube atmospheric pressure air discharge plasma jet. The investigation reveals that: pH is decreased, while electrical conductivity (EC) is increased in the deionized (DI) waters and model WWs with increasing plasma treatment duration. The Concentrations of O3, H2O2 and NO3- in model WWs are decreased compared to that of DI water with treatment duration, but NO2- is increased. The decrease in O3, H2O2 and NO3- suggest that they participate in the dissociation processes of textile dyes. UV–vis spectroscopic measurements show that almost 70 % of dyes were degraded within 10 min of treatments but the remaining 30 % was taken a longer time. FTIR spectroscopic measurements reveal that the amines and alkynes are likely to be produced through oxidative processes of azo-bonds and nitrogen containing functional groups with the interactions of O3 and OH radical. A fraction of organic nitrogen can be converted to nitrites through oxidation for which the concentration of nitrite is increasing with treatment duration. The proposed environment friendly plasma technology can alternatively be adapted to the reduction of effluents as dissolve in textile WW.