活性炭对天然有机物氯化过程消毒副产物生成的影响及作用机制

Effect and mechanism of activated carbon on the generation of disinfection by-products during chlorination process of dissolved organic matter

活性炭(AC)与氯均为水处理过程中广泛使用的药剂,在实际使用过程中二者的接触不可避免,因此,深入研究AC对于氯化过程中消毒副产物(DBPs)生成的影响对于饮用水安全有重要意义。本研究对比了AC对于溶解性天然有机物(DOM)氯化过程中已知DBPs(包括三卤甲烷(THMs)和卤乙酸(HAAs))生成释放的影响,并采用傅立叶变换离子回旋共振质谱(FTICR-MS)技术检测分析其滤后水的未知氯化副产物及有机物变化规律。结果表明,在DOM氯化过程中,AC存在时释放的THMs和HAAs浓度较低,但氯的衰减速率更快,这是由于AC本身的强还原性及其他氯代副产物生成导致的。进一步通过FTICR-MS分析未知氯代产物及DOM的变化发现,在2种条件下有163种相同的氯化产物,与不存在AC时对比,AC存在时生成了不同的氯化产物中有57种。此外,AC存在时CHOCl、CHONCl和CHONSCl分子式的数量减少,而CHOSCl分子式的数量增加,并且具有芳香结构的DOM更容易被转化。通过电子自旋共振谱仪(ESR)分析发现AC表面的持久性自由基激发次氯酸钠反应生成的氯自由基(Cl·)是导致氯化产物变化的主要原因。本研究揭示了AC对氯化过程DBPs的生成影响,对于饮用水DBPs控制具有重要意义。

Activated carbon(AC)and chlorine are both widely used agents in the water treatment process,and their contact is inevitable during the actual use.Therefore,it is important to study the effects of AC on the generation of disinfection by-products(DBPs)during the chlorination process for the safety of drinking water.Therefore,in this study,the effects of AC on the concentration of known DBPs including trihalomethanes(THMs)and haloacetic acids(HAAs)formed during the chlorination of dissolved organic matter(DOM)were compared,and the unknown chlorination byproducts and the transformation of organics in effluent were analyzed by using the Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS)technique detection.The results showed that during DOM chlorination,lower concentrations of THMs and HAAs were released in the presence of AC,but the rate of chlorine decay was faster,which was due to the strong reducing property of AC itself and the generation of other chlorinated by-products.Further analysis of the unknown chlorinated products and changes in DOM by FTICR-MS revealed that there were 163 identical chlorination products under the two conditions,and 57 of the different chlorination products were generated in the presence of AC compared to the absence of AC.In addition,the numbers of CHOCl,CHONCl,and CHONSCl molecular formulas decreased,while the number of CHOSCl molecular formulas increased,and DOM with an aromatic structure was more easily converted in the presence of AC.The main reason for the change in chlorination products is the generation of chlorine radicals(Cl·)from the reaction of sodium hypochlorite activated by the persistent radicals on the surface of AC through electron spin resonance spectroscopy(ESR)analysis.This study reveals the effects of AC on the generation of DBPs during chlorination,which is important for the control of DBPs in drinking water.