This work focuses on the optimization of operating conditions of the electro-Fenton process for a clean and efficient elimination of sulfamethazine, a persistent antibiotic regularly detected in wastewater. The study of the effects of experimental parameters, including current intensity, electrolysis duration and ferrous ion concentration, as well as their interaction, was carried out by response surface methodology based on a Doehlert experimental design. The results obtained showed that under specific conditions (0.5 mM ferrous ions, 0.5 A, 50 mM sodium sulfate, at pH 3), an almost complete mineralization (90%) of sulfamethazine was obtained from an initial concentration of 0.2 mM. A statistically significant quadratic polynomial model was developed and validated by an analysis of variance (ANOVA). The high coefficient of determination (R2 = 0.99) and the low p-value (0.00014) confirm the strong predictive capacity and overall relevance of the model. The energy consumption of this system was determined to be 1.2 kilowatt-hours per gram of total organic carbon (TOC) removed. In addition, the short-chain carboxylic acids and inorganic ions produced were quantified and tracked throughout the treatment process. Due to its high durability and efficiency, the electro-Fenton method is considered a very promising technology for wastewater treatment. Its ability to completely mineralize organic pollutants without generating harmful by-products makes it a particularly wise choice.
