Removal of C.I. Basic Blue 41 from aqueous solution by supercritical water oxidation in continuous-flow reactor

Oxidation of aqueous solution of C.I. Basic Blue 41 (BB41), which is model azo dye pollutants, was studied in a continuous-flow reactor that was operated between 400 and 650 °C at a fixed pressure of 25 MPa. The total organic carbon (TOC) concentration of BB41 was in the range of 30.60 and 152.97 mmol/L in the feed stock solution. Hydrogen peroxide (H2O2) was used as an oxygen source and the oxidant concentrations were between 73.53 and 489.64 mmol/L in the feed stock solution. The results demonstrated that supercritical water oxidation (SCWO) process decreases the TOC up to 99.87% in very short reaction times (at residence times of 9–19 s). According to the wastewater and oxidant concentrations, the global rate expression was regressed from the complete set of data for each dye solution. As a result of regression analysis, the reaction rate expression for the oxidation of BB41 was determined with the activation energy of 18.88 (±0.9) kJ/mol and the pre-exponential factor of 2.8 (±0.5) mmol−0.16 L0.16 s−1; and the reaction orders for BB41 (based on TOC) and the oxidant were 0.84 (±0.03) and 0.32 (±0.05) in a 95% confidence level.