Copper increases reductive dehalogenation of haloacetamides by zero-valent iron in drinking water: Reduction efficiency and integrated toxicity risk

WATER RESEARCH

卷:107

Article

Chu, Wenhai¹  Li, Xin¹  Bond, Tom²  Gao, Naiyun¹  Bin, Xu¹  Wang, Qiongfang¹  Ding, Shunke¹ 

[1] Tongji Univ, State Key Lab Pollut Control & Resources Reuse, Inst Disinfect Byprod Control Water Treatment, Coll Environm Sci & Engn, Shanghai 200092, Peoples R China

[2] Imperial Coll London, Dept Civil & Environm Engn, London SW7 2AZ, England

关键词: Disinfection byproducts;    Haloacetamides;    Dechlorination;    Zero-valent iron/copper;    Integrated toxicity risk;    Drinking water;   

DOI  :  10.1016/j.watres.2016.10.047

来源: Elsevier

【 摘 要 】

The haloacetamides (HAcAms), an emerging class of nitrogen-containing disinfection byproducts (NDBPs), are highly cytotoxic and genotoxic, and typically occur in treated drinking waters at low mu g/L concentrations. Since many drinking distribution and storage systems contain unlined cast iron and copper pipes, reactions of HAcAms with zero-valent iron (ZVI) and metallic copper (Cu) may play a role in determining their fate. Moreover, ZVI and/or Cu are potentially effective HAcAm treatment technologies in drinking water supply and storage systems. This study reports that ZVI alone reduces trichloroacetamide (TCAcAm) to sequentially form dichloroacetamide (DCAcAm) and then monochloroacetamide (MCAcAm), whereas Cu alone does not impact HAcAm concentrations. The addition of Cu to ZVI significantly improved the removal of HAcAms, relative to ZVI alone. TCAcAm and their reduction products (DCAcAm and MCAcAm) were all decreased to below detection limits at a molar ratio of ZVI/Cu of 1:1 after 24 h reaction (ZVI/TCAcAm = 0.18 M/5.30 mu M) TCAcAm reduction increased with the decreasing pH from 8.0 to 5.0, but values from an integrated toxic risk assessment were minimised at pH 7.0, due to limited removal MCAcAm under weak acid conditions (pH = 5.0 and 6.0). Higher temperatures (40 degrees C) promoted the reductive dehalogenation of HAcAms. Bromine was preferentially removed over chlorine, thus brominated HAcAms were more easily reduced than chlorinated HAcAms by ZVI/Cu. Although tribromoacetamide was more easily reduced than TCAcAm during ZVI/Cu reduction, treatment of tribromoacetamide resulted in a higher integrated toxicity risk than TCAcAm, due to the formation of monobromoacetamide (MBAcAm). (C) 2016 Elsevier Ltd. All rights reserved.

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