Kinetic modeling of a triarylmethane dye decolorization by photoelectro-Fenton process in a recirculating system: Nonlinear regression analysis

•Kinetic modeling of photoelectro-Fenton process by non-linear regression analysis.•Investigation of the effective parameters on photoelectro-Fenton process.•Evaluation of consumed electrical energy in the various operational conditions. The treatment of C.I. Acid Blue 5 solution by electrochemical process was studied under recirculation mode with a cathode containing multi walled carbon nanotubes in the presence of sodium sulfate electrolyte. Comparison of electro-Fenton and photoelectro-Fenton processes at pH 3.0 revealed that 23.04 and 98.25% of the dye was decolorized at 60min, respectively. The kinetic of dye removal by photoelectro-Fenton process was studied with nonlinear regression analysis. A kinetic model was developed for estimation of pseudo-first order rate constant (kapp) as a function of operational parameters including initial concentration of the dye (10–50mg/L), flow rate (5–20L/h), pH (3–9), initial concentration of Fe3+ (0.05–0.2mM) and applied current (0.05–0.45A). The calculated results, which were obtained from kinetic model, were in consistent with the experimental data (R2=0.9934). The calculated and experimental data were applied for prediction of the electricity consumption in decolorization processes.