Effect of chloride concentration on the oxidation of EDTA in UV-FSR oxidative system

This study focused on the effect of chloride concentration and pH on the photochemical degradation of ethylenediaminetetraacetic acid–disodium salt (C10H14N2Na2O8·2H2O, EDTA) under advanced oxidation using UV/H2O2 system. The treatment of this chemical by UV/H2O2 oxidation using a laboratory scale UV-free surface reactor (UV-FSR) with (1000 and 10,000 mg/l Cl−) and without Cl− addition at different pH values (pH 3, 7 and 10) was compared. Results of this study indicated that Cl− concentration is more decisive than pH in the oxidation process. There was no AOX at the start of the experiments but as a result of oxidation a de novo synthesis of AOX was observed, and these AOXde novo compounds were destroyed during the treatment. Treatment was followed by TOC and AOX measurements. Approximately 95% TOC removal efficiency was obtained for the treatment of EDTA-containing synthetic water. Owing to kinetic studies, it was found that the TOC degradation in all experiments fitted to the first order reaction law.