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 con-centration 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.