Abstract：
The formation of brominated disinfection byproducts (Br-DBPs) is an emerging issue in drinking water disinfection because its toxicity is tens to hundreds of times higher than that of chlorinated analogues and because of the widespread presence of bromide in source water. However, the mechanism and pathways of Br-DBPs formation remain unclear. In this study, we used glycine, alanine, and serine as model precursors and observed that brominated haloacetonitriles (Br-HANs) were more likely to be formed than brominated trihalomethanes. The results showed that there is not only one important way to HAN formation in the presence of bromide. We propose that organic bromamines, similar to organic chloramines, play a significant role in the formation of Br-HANs. Both the experimental and theoretical results confirmed that the decay of organic bromamines was faster than that of organic chloramines, which verified our assumption. The effect of the pH was investigated to further confirm the role of organic bromamines. In addition, we found that the formation of Br-HANs was significantly inhibited when monochloramine was used as a disinfectant, because the formation of organic bromamines was blocked. However, the formation of Br-HANs was promoted during the UV/chlorine process because of the faster decay of organic bromamines under UV photolysis. Overall, our study reveals the formation mechanism of Br-HANs and provides an alternative method to prevent Br-HAN formation.
摘要：
溴化消毒副产物（Br-DBPs）的形成是饮用水消毒中的一个新兴问题，因为其毒性比氯化类似物高数十倍至数百倍，并且由于源水中广泛存在溴化物。然而,Br-DBPs形成的机制和途径尚不清楚。在这项研究中,我们用甘氨酸,丙氨酸,和丝氨酸作为模型前体，并观察到溴化卤代乙腈（Br-HANs）比溴化三卤代甲烷更有可能形成。结果表明，溴化物的存在不仅是HAN形成的重要途径之一。我们建议有机溴胺，类似于有机氯胺，在Br-HAN的形成中起着重要作用。实验和理论结果都证实，有机溴胺的衰变比有机氯胺的衰变快，这证实了我们的假设。研究pH的影响以进一步证实有机溴胺的作用。此外,我们发现，Br-HANs的形成被显著抑制时，一氯胺被用作消毒剂，因为有机溴胺的形成被阻断了。然而,在UV/氯过程中，由于有机溴胺在UV光解作用下的衰减更快，因此促进了Br-HAN的形成。总的来说,我们的研究揭示了Br-HAN的形成机制，并提供了一种防止Br-HAN形成的替代方法。
