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选择甲基叔丁基醚为萃取剂,1,2-二溴丙烷为内标物,采用气相色谱/质谱法,建立了含氮消毒副产物二氯乙腈(DCAN)的测定方法.以天冬氨酸为前体物,研究饮用水氯化消毒过程中二氯乙腈的形成过程及影响因素,并探讨了二氯乙腈的生成机制.结果表明,在酸性及中性条件下,DCAN的生成量随着p H值的增大而增大,在碱性条件下,DCAN的生成量随着p H值的增大而减小,并且碱性条件下DCAN的生成量明显比中性和酸性条件下低.投氯量增加,DCAN的生成量也随之不断提高.在10~30℃范围内,温度对形成DCAN的影响不大.天冬氨酸氯化形成DCAN的过程包括7个步骤,经过一系列包括取代、脱羧、氧化等反应后,最终形成DCAN.
A method for determination of dichloroacetonitrile (DCAN), a nitrogenous disinfection by-product, was established by gas chromatography / mass spectrometry using methyl tert-butyl ether as extractant and 1,2-dibromopropane as internal standard. Amino acid as precursor to study the formation process and influencing factors of dichloroacetonitrile in drinking water chlorination process and discuss the formation mechanism of dichloroacetonitrile.The results showed that under acidic and neutral conditions, With the increase of p H value, under alkaline conditions, the amount of DCAN decreases with the increase of p H value, and the formation of DCAN under alkaline conditions is significantly higher than that of neutral and acidic conditions And the amount of DCAN increased.The amount of DCAN also increased continuously.The temperature had little effect on the formation of DCAN in the range of 10 ~ 30 ℃ .The formation of DCAN by aspartic acid chlorination included 7 steps, After a series of including substitution, decarboxylation, oxidation and other reactions, the final formation of DCAN.