Influencing factors on performance of electro-oxidation and UV/electro-oxidation for removal of atrazine: Kinetics, long-term stability and toxicity

Performance of electro-oxidation (EO) and UV/electro-oxidation (UV/EO) on atrazine (ATZ) removal was investigated under various operating factors. Because of synergistic effect on ATZ removal, UV/EO was the most effective process, followed by UV/chlorine, EO, UV irradiation, and chlorination, respectively. Although the energy consumption of UV/EO for 90% removal was similar to that of EO, UV/EO removed ATZ 1.8 times faster than EO. Boron doped diamond (BDD) exhibited greater ATZ removal than dimensionally stable anode (DSA), and performance of BDD was stable for treatment of 50 cycle times (100 h). Performance of EO and UV/EO on ATZ removal increased with higher current density and low pH. ATZ removal by EO and UV/EO was independent to NaCl concentrations (300–1000 mg.L−1). HO• played a major role on ATZ removal, while the role of RCS was minor. The 2nd-order reaction rate constant of HO• with ATZ (𝑘𝐴𝑇𝑍−𝐻𝑂•) was 1.36 × 109 M−1s−1. Although phytotoxicity was a sensitive endpoint to ATZ, different inhibition on germination of Ipomoea aquatica and Oryza sativa L. (Khao Dawk Mali 105) seeds was observed. UV/EO was the most effective process for ATZ detoxication. Germination index of Ipomoea aquatica and Oryza sativa L. (Khao Dawk Mali 105) seeds for samples treated by UV/EO was equivalent or greater than the control sample.