Electro-Fenton Degradation of Trimellitic and Pyromellitic Acids: Kinetics and Mechanism

This paper describes the application of electro-Fenton technology to decontaminate waters containing trimellitic and pyromellitic acids. In this technique, the electrogeneration of hydroxyl radicals (•OH) leads to the oxidative degradation of the benzene polycarboxylic acids until their total mineralization. The effect of the operating parameters on the trimellitic acid removal was studied. Under the optimal conditions (C0 = 2.10−4 M, [Fe2+] = 0.3 mM, I = 300 mA, [Na2SO4] = 0.05 M, pH = 3), the mineralization of pyromellitic and trimellitic acid solutions was followed by chemical organic demand (COD) measurements after 4 and 5 h of electrolysis time, respectively. The highest disappearance rate of the pyromellitic acid is due to its greater reactivity compared to the trimellitic acid towards the hydroxyl radicals. The products resulting from degradation of pyromellitic acid were identified by using UPLC/MS. The identified by-products allowed proposing a degradation pathway for the pyromellitic and trimellic acids.