Removal of acetaminophen from hospital wastewater using electro-Fenton process

The current work deals with efficient removal of acetaminophen (AC) from hospital wastewater using electro-Fenton (EF) process. The degradation yield of 99.5% was obtained under optimal experimental conditions, namely 5.75 mg L-1 initial AC concentration, 2.75 pH solution, 3-cm inter-electrode distance, 100 mg L-1 KCl electrolyte, 122.5 mu L L-1 H2O2, 8 mA cm(-2) current density at equilibrium time of 8 min. Analysis of variance (ANOVA) suggested that the effect of mentioned operating parameters was statistically significant on the AC removal. The low probability amount of P value (P < 0.0001), the Fisher's F-value of 65.91, and correlation coefficient of the model (R-2 = 0.9545) revealed a satisfactory correlation between the experimental and the predicted values of AC removal. The predicted removal efficiency of 99.4% was in satisfactory agreement with the obtained experimental removal efficiency of 98.7%. The AC degradation during the EF followed a first-order kinetic model with rate constants (K-app) of 0.6718 min(-1). Using the ordinary radical scavengers revealed that main mechanism of AC degradation controlled by the hydroxyl free radicals produced throughout the EF process. The excess amount of iron (II) scavenged the active radicals and diminished the concentration of OH available to react with AC. The optimum molar ratio of H2O2 to -Fe2+ was found to be 2.5. The developed EF process as a promising technique applied for treatment of real samples.