Abstract / Summary
The difficulty of removing organic pollutants, particularly synthetic dyes, from water poses a serious environmental challenge due to conventional treatment methods often suffering from high energy consumption or secondary waste generation. Our study presents a multiparametric investigation of an electrolyte-plasma water treatment process for the degradation of methyl orange, used as a model organic contaminant, in aqueous sodium carbonate solutions. The effects of electrolyte concentration (5–10 wt.% Na2CO3), applied voltage (up to 200 V), current electric density, temperature (from room temperature to 95 °C), and electrode area on discharge ignition, stability, and power consumption were systematically studied. It was shown that increasing the Na2CO3 concentration from 5 to 10 wt.% reduces the ignition voltage from 185 to 160 V at 65 °C, owing to enhanced solution conductivity, while stable plasma burning is achieved at 70–90 °C with currents of 0.3–0.5 A and a power input below 5 kW/L. Kinetic studies of methyl orange decomposition (initial concentrations 5.3–49.9 mg/L) revealed that the reaction follows the pseudo-first-order kinetics equation (R2 > 0.99). The process requires no external reagents and achieves >98% decolorization of the dye within 110 min. Elemental analysis of the solid residue indicates the formation of carbonaceous and titania particles, suggesting that partial mineralization occurs. However, further studies including total organic carbon (TOC) analysis and identification of possible aromatic intermediates are needed to confirm complete mineralization and the absence of toxic by-products. These findings establish a scientific basis for scaling up the electrolyte-plasma water treatment process, offering an energy-efficient, environmentally benign alternative for the destruction of organic pollutants in water.