[Removal Efficiency of Trichloroacetamide by UV/Sodium Sulfite]

Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection by-products (N-DBPs) with high cytotoxicity and genotoxicity, which are widely detected in drinking water. The toxicity of trichloroacetamide (TCAcAm) is significantly higher than traditional DBPs. In this study, ultraviolet (UV) treatment was combined with sodium sulphite (Na₂SO₃) to remove TCAcAm from water. The effects of different light intensities, different agent dosages (Na₂SO₃), and pH conditions on the removal of TCAcAm by UV/Na₂SO₃ advanced reduction process were investigated. The results showed that TCAcAm could be rapidly degraded by the UV/Na₂SO₃ system. The degradation effect was directly proportional to light intensity, dosage of Na₂SO₃, and pH. Moreover, the pH had a significant effect on the reaction rate and degradation rate. As the pH increased from 6 to 9, the degradation rate of TCAcAm increased from 12.8% to 99.6%, in 120 min. The removal rate of TCAcAm reached 99.4% when the UV light intensity, pH, Na₂SO₃ dosage, and reaction time were 450 μW·cm^-2, 9, 1.00 mmol·L^-1, and 30 min, respectively. The experimental results indicated that the UV/Na₂SO₃ system is an efficient advanced reduction process for the removal of TCAcAm, and it has the potential to reduce other halogenated DBPs. Therefore, it could be used for the degradation of halogenated DBPs in the treatment of drinking water.