Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Environ Sci Technol. 2010 Mar 15;44(6):2105-11. doi: 10.1021/es903077y.
Total organic halogen (TOX) is a collective parameter and a toxicity indicator for all the halogenated organic disinfection byproducts (DBPs) in a water sample. TOX can be measured with the adsorption-pyrolysis method based on Standard Method 5320B. This method involves concentration of organic halogens from water by adsorption onto activated carbon (AC) and removal of inorganic halides present on the AC by competitive displacement by nitrate ions. Since AC can also act as a reductant, this work studied whether the reduction of chlorinated DBPs by AC occurs during the TOX measurement, to what extent the reduction affects the measurement of TOX, what type of chlorinated DBPs can be reduced by AC, and whether the method for the TOX measurement can be improved. Initially, chlorinated Suwannee River fulvic acid samples were prepared and pretreated with precipitation/dialysis/ultrafiltration to minimize the chloride levels in the samples. It was found that the fractions of TOX in the precipitated, dialyzed, and ultrafiltered samples that were reduced by AC in 5 min were around 13%, 20% and 24%, respectively. The formation of some N-chloroamino compounds and their reactivity with AC were examined. The results indicate that organic chloramines are one type of DBPs in TOX that could be reduced by AC. It was demonstrated that slight oxidation of AC with ozone basically inhibited its reduction for TOX and meanwhile maintained its adsorption capacity for TOX.
总有机卤素 (TOX) 是一个综合参数，也是水样中所有卤代有机消毒副产物 (DBP) 的毒性指标。可以采用基于标准方法 5320B 的吸附-热解方法来测量 TOX。该方法涉及通过吸附到活性炭 (AC) 上来浓缩水中的有机卤素，并通过硝酸盐离子的竞争置换去除 AC 上存在的无机卤素。由于 AC 也可以作为还原剂，因此本工作研究了 AC 在测量 TOX 期间是否会还原氯化 DBP，还原程度对测量 TOX 的影响，AC 可以还原哪种类型的氯化 DBP，以及是否可以改进用于测量 TOX 的方法。最初，制备了氯化苏万尼河富里酸样品，并通过沉淀/透析/超滤预处理以最大限度地降低样品中的氯化物水平。结果发现，在 5 分钟内用 AC 还原的沉淀、透析和超滤样品中，TOX 的分数分别约为 13%、20%和 24%。还检查了一些 N-氯代氨基化合物的形成及其与 AC 的反应性。结果表明，有机氯胺是 AC 可还原的 TOX 中的一种 DBP。结果表明，臭氧轻微氧化 AC 基本抑制了其对 TOX 的还原，同时保持了其对 TOX 的吸附能力。
