Effect of Chlorine Dioxide on the Removal of Sulfadimethoxine and Sulfamethoxazole in Freshwater and Seawater

Abstract

This study aimed to understand the fate of sulfonamides (SAs) under dark condition in a laboratory-scale aquatic system, and evaluate the removal of SAs by using Chlorine dioxide. Based on the mass spectrometry quantification, our results have shown that two sulfonamides were transformed at very slow rate in the dark. The 180 day degradation efficiencies (%) of sulfadimethoxine (SDM) in freshwater and seawater were 6.37 +/- 2.56 and 4.38 +/- 3.43, respectively, while those of sulfamethoxazole (SMX) in freshwater and seawater were 7.81 +/- 2.15 and 6.60 +/- 2.69, respectively. In the treatment of Chlorine dioxide for the removal of SAs in freshwater and seawater, it was found that the complete removals can be achieved within 7 day at the 1:1 ratio. The removal efficiencies increased significantly as the concentration ratio of treatment increasing to 5:1 and 10:1. SDM (0.1 mg/L) in freshwater was removed completely at 7.0, 2.0 and 0.5 day by treating Chlorine dioxide of 0.1, 0.5, and 1.0 mg/L, respectively. It was noted that the removals of SDM in seawater were improved to 0.25 day in both treatments of 0.5 and 1.0 mg/L. Similar improvements were also observed in the removal of SMX (0.1 mg/L) under the same treatment. The complete removal of SMX in freshwater was done at 7.0, 2.0 and 0.5 day, respectively, whereas that of SMX in seawater was done at 4.0, 0.25 and 0.25 day, respectively.