氯消毒衍生氯代苯甲醚类土霉味物质的生成与控制机制研究

The taste and odor compounds are easily formed after chlorination in the network, causing there is unpleasant taste and odor in tap water even though the effluent water gets the water quality standards. The chloroanisole compounds with earthy and musty odor, has lower smell threshold, are more difficult to remove and more easily to formed by chlorination than 2-MIB and Geosmin, which were more concerned before. The six representative chloroanisole compounds are chose to be the research objects. The open loop stripping analysis (OLSA) combined with solid phase microextraction (SPME) technology will be developed to enrich the super trace (<ppt) volatile organic compounds. The quantitative analysis method of kinds of taste and odor compounds will be established. The migration and transformation about six kinds of chloroanisole compounds in the specific waterworks and urban pipeline effluent will be explored. The formation potential of chloroanisole compounds will be discussed and the forecast models will be established. In the further research, we will grasp the key control factors and restrictive conditions of the formation, and identify the key precursors and special functional groups. The possibility of either anisole chlorination or chlorophenol biomethylation will be proved .Besides, their reaction mechanism and the generation paths will also be revealed. According to the key precursor and the restraining factors, the technology and theory of controlling the chloroanisole compounds will be investigated.

水厂氯消毒衍生的嗅味物质易在管网中持续反应，造成出厂水达标但龙头水存在异嗅异味的反常现象。新发现的土霉味物质氯代苯甲醚类，较倍受关注的2-MIB和土嗅素，具有嗅阈值更低、去除难度更大、氯化后更易生成等特点。选取典型的6种氯代苯甲醚为研究对象，将开环捕集与固相微萃取相结合，开发超痕量（<ppt级）挥发性有机物浓缩富集技术，建立多种嗅味物质同时定量分析的方法；探索特定水厂的出水和城市管网水中的6种氯代苯甲醚的迁移转化规律。深入研究给水管网内氯代苯甲醚类物质的生成潜能并建立预测模型；掌握氯化衍生的关键控制因素和制约条件；识别易产生氯代苯甲醚类嗅味物质的关键前体物和特征官能团；验证苯甲醚氯代化和氯酚生物甲基化的可能性；揭示出反应机制和主要生成路径。通过关键前体物和制约因素的确定，提出从源头和过程控制氯代苯甲醚生成的工艺理论，从根本上使氯衍生的嗅味物质减量化。

水厂氯消毒衍生的嗅味物质易在管网中持续反应，造成出厂水达标但龙头水存在异嗅异味的反常现象。新发现的土霉味物质氯代苯甲醚类，较倍受关注的2-MIB和土臭素，具有嗅阈值更低、去除难度更大、氯化后更易生成等特点。.本项目建立了大体积浓缩、固相微萃取-气质联用的方法进行同时测定包括2,4,6-三氯苯甲醚（TCA）、2-甲基异崁醇(2-MIB)、土臭素（GSM）等6种痕量致嗅物质。自制大体积玻璃萃取瓶，确定了最优的萃取条件，成功应用于江河湖泊、自来水出厂水和管网末端水等水体中嗅味物质的定量检测，相关研究成果发表于SCI杂志《分析化学》2013年第5期。.在研究氯代苯甲醚的生成机理中，首先肯定了两种前体物的猜想：一是苯甲醚氯化作用产生；一是氯酚生物甲基化后能产生。尤其以后者为水体中氯代苯甲醚的主要来源。在氯消毒苯甲醚过程中，pH对反应起决定性作用，苯甲醚只能在酸性和弱酸性条件下才能发生氯代反应，加氯量、苯甲醚初始浓度、温度的提高不仅加快了反应速率也加大了氯代苯基醚的生成量，其反应机理及动力学发表于EI杂志《同济大学学报（自然科学版）》2015年第1期。研究了微生物将2,4,6-三氯酚甲基化转化为2,4,6-三氯苯甲醚的可行性及生成路径。探索了不同微生物甲基化的能力，微生物甲基化的来源种类，甲基化环境影响因素如：溶解氧、温度、TOC、藻类密度等，以及实际水体中通过生物甲基化产生氯代苯甲醚的时空分布情况。相关研究成果正在撰写学术论文，并已获得一项发明专利。