Electro-Fenton Oxidation of Salicylic Acid from Aqueous Solution: Batch Studies and Degradation Pathway

This study investigated the removal of salicylic acid (SA) from aqueous solution by electro-Fenton (EF) and EF-like processes using graphite-graphite electrolytic system. Fe-0, Fe2+, Fe3+ ions were used as the Fenton reagent in the EF process and in the EF-like reactions, Cu2+, Mn2+, Ni2+ were used as the same. The effect of various operating conditions on the effectiveness of EF process was investigated. The contribution of adsorption and electro-sorption in the removal of SA was also investigated. According to the results, EF method can be used efficiently for the removal of SA by maintaining proper operating conditions. Fe2+ was confirmed to be the most efficient catalyst among the metal ions that were tested. Maximum removal efficiency of 75.13% was obtained under optimal operating conditions after 8 h of electrolysis. Even though EF-like processes are also effective for the removal of SA from aqueous solutions, EF removal of SA was observed to be more efficient for the same. Gas chromatography-mass spectrometry (GC-MS) of SA solutions electrolyzed at optimal conditions was carried out. Degradation pathway was proposed from GC-MS.