Reactive yellow 145 removal by electro-Fenton with Fe-carbon fiber electrode pair: optimization of process variables based on response surface methodology

Wastewater containing reactive textile dyes constitutes a crucial environmental problem as they are permanent and dangerous. The electro-Fenton (EF) method is promising as an effective technique for degrading organic materials such as dyestuffs. In this study, the optimization of influential variables in removing reactive yellow 145 azo textile dye by EF was investigated using response surface methodology (RSM). Central composite design was used to study the combined effects of critical parameters such as voltage (2.5-12.5 V), H2O2 addition (0.1-1.3 mL), pH (1.75-4.75), electrode spacing (0.25-3.25 cm), and treatment time (25-85 min). The optimum values of the variables to ensure the highest dye removal efficiency (approx. 93%) with the lowest energy consumption (approx. 3.4 Wh/L) were approximately 9.4 V voltage, pH 3.7, 2.5 cm electrode spacing, 1 mL H2O2 addition, and a 40-min treatment time. ANOVA analysis of the predicted quadratic polynomial model showed a regression coefficient value of approximately 0.97 for both objective functions; this highlights the model's applicability for navigating the design space. Simultaneous optimization of process parameters using RSM was achieved with a few experiments.