Degradation of emerging contaminant coumarin based on anodic oxidation, electro-Fenton and subcritical water oxidation processes

• Published in: Environmental research 2022-05, Vol.208, p.112736-112736, Article 112736
• Main Authors: Görmez, Özkan, Akay, Sema, Gözmen, Belgin, Kayan, Berkant, Kalderis, Dimitrios
• Format: Article
• Language: English
• Subjects: Anodic oxidation; Coumarin; Coumarins; Electro-Fenton; Electrodes; Emerging contaminant; Hydrogen Peroxide; Oxidation-Reduction; Subcritical water oxidation; Water; Water Pollutants, Chemical - analysis
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2022.112736

The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-Fenton and subcritical water oxidation processes. With respect to the anodic and electro-Fenton oxidation, the influence of constant current, treatment time and initial concentration of coumarin was studied. Regarding subcritical water oxidation, the effect of the oxidant concentration, temperature, treatment time and initial coumarin concentration was investigated. In anodic and electro-Fenton oxidation processes, coumarin degradation proceeded in a similar manner, achieving 99% degradation, after 180 min at a constant current of 200 mA. In both set-ups, further increasing the applied current lowered the degradation efficiency due to the formation of by-products and the increasing occurrence of side-reactions. The highest degradation of 88% was achieved in subcritical conditions, specifically at 200 °C, using 150 mM H2O2 and after 37.5 min of treatment. Under subcritical conditions, temperature was the most prominent parameter, followed by the H2O2 concentration. Under all methodologies, increasing treatment time had a small positive effect on coumarin degradation, indicating that time is not the most influential parameter. A comparison of the three methodologies in terms of performance as well as energy consumption and simplicity of operation highlighted the advantages of subcritical water oxidation. •Degradation of coumarin was investigated using three different oxidation processes.•>99% degradation was achieved in anodic and electro-Fenton oxidation processes.•Subcritical water oxidation at 200 °C achieved 88% degradation after 37.5 min.•O-coumaric acid, salicylaldehyde and catechol were intermediate products under subcritical conditions.