Ca^(2+)、Mg^(2+)对饮用水氯消毒过程中三卤甲烷生成的影响

Effects of Ca^(2+) and Mg^(2+) on Formation of THMs during Disinfecion of Drinking Water by Chlorine

以腐殖酸模拟天然水体中氯化消毒副产物的前驱物进行实验,研究了水中存在Br-、不同pH条件下,Ca^(2+)、Mg^(2+)单独存在和2种离子共存时对三卤甲烷(THMs)的生成量和4种THMs(CHCl_3、CHBrCl_2、CHBr_2Cl、CHBr_3)相对分布的影响。结果表明,在pH为6.0、7.0、9.0 3种条件下,Ca^(2+)、Mg^(2+)对THMs的生成均起到一定的抑制作用,并且Mg^(2+)比Ca^(2+)对THMs生成的抑制作用更强。此外,随着pH的升高THMs生成总量增加,说明碱性环境更有利于THMs的生成。偏酸性环境下,Ca^(2+)的存在有利于溴代三卤甲烷的生成,Mg^(2+)有利于氯代三卤甲烷的生成。Ca^(2+)、Mg^(2+)浓度超过1.0 mg/L后,对THMs生成有较明显抑制作用。中性环境下,Ca^(2+)单一存在时,随着Ca^(2+)浓度的增加THMs的生成总量先增后减,并且在Ca^(2+)浓度为2.5 mg/L时达到最大值,此时Ca^(2+)有利于氯代三卤甲烷的生成;Ca^(2+)、Mg^(2+)同时存在时,THMs的生成分布改变,溴代三卤甲烷的生成显著增多。

Humic acid solutions were used as disinfection by-products（DBPs） model precursors of natural water,to study the water that has bromide ions under different environmental conditions,and the effects on the formation of trihalomethanes（THMs） and the relative distribution of CHCl_3, CHBrCl_2, CHBr_2Cl and CHBr_3 in the presence of Ca^（2＋）, Mg^（2＋） single and co-existence. The results showed that at the conditions of pH of 6.0,7.0 and 9.0,Ca^（2＋）, Mg^（2＋） has played a certain inhibition to THMs. Alkaline environment is more conducive to the generation of THMs and Mg^（2＋） is stronger than Ca^（2＋） inhibition of THMs generated. Under acidic environment,Ca^（2＋） is conducive to the generation of brominated THMs and Mg^（2＋） is conducive to chlorinated THMs. After the concentration exceeds 1.0 mg/L, Ca^（2＋）, Mg^（2＋） for THMs generation has been significantly inhibited.At neutral environment, when Ca^（2＋） single existence, with the increasing concentration of Ca^（2＋）, the total generation of THMs decreases after the first increase. In addition, the total amount reaches a maximum during the calcium ion concentration achieved 2.5 mg/L,at this time Ca^（2＋） is in favor of chlorinated trihalomethanes generation. Containing both Ca^（2＋） and Mg^（2＋）,THMs＇ distributed generation changed and brominated trihalomethanes generation increased significantly.