Electro-Fenton degradation of anionic surfactants

• Electrochemical removal of anionic surfactant using a graphite-felt cathode was studied.
• We examine the influence of the main operating parameters affecting the treatment.
• Kinetic of surfactant oxidation was monitored.

The degradation of sodium dodecyl benzene sulfonate (LAS), a common industrial and household anionic surfactant, has been investigated by electro-Fenton process at constant current. The electrolyses have been performed using an undivided cell equipped with a Ti/RuO2 anode and a commercial graphite-felt to electrogenerate in situ hydrogen peroxide and regenerate ferrous ions as catalyst. The effect of operating conditions such as applied current, catalyst concentration, initial surfactant concentration and initial pH has been studied. Surfactant decay kinetic was monitored during the electrolysis by UV–vis measurements.The experimental results showed that LAS was completely removed by the reaction with OH radicals generated from electrochemically assisted Fenton’s reaction, and the decay kinetics always follow a pseudo-first-order reaction. With our cell design, the higher oxidation rate has been obtained applying a current of 200 mA, at pH 3 and in the presence of 0.3 mM Fe2+ as catalyst. In these conditions, after 180 min of electrolysis almost complete oxidation of 50 mg dm−3 of LAS has been obtained with a specific energy consumption of 9.53 ± 0.5 kW h m−3.