Comparative study of Rhodamine B and Direct Orange 39 degradation in aqueous solution using atmospheric plasma

The inadequate treatment of industrial wastewater with organic contaminants is a worldwide problem, requiring the development of alternative wastewater treatment methods. This study focused on the degradation and mineralization processes of two dyes, Rhodamine B and Direct Orange 39, in water using atmospheric plasma. Aqueous solutions of the dyes were treated at an initial concentration of 1.0 mM in a volume of 250 mL using iron filings (Fe2+) as a catalyst. Their absorption spectra in the ultraviolet–visible range, total organic carbon, and chemical oxygen demand were monitored. Furthermore, their physicochemical properties such as pH, electrical conductivity, and nitrate and nitrite concentrations were determined. The results showed a process efficiency greater than 90% for both dyes owing to atmospheric plasma exposure.