光催化降解和光降解氯代乙酸的研究-环境科学与工程 环境工程专业论文.docxVIP

兰州大学硕士学位论文 兰州大学硕士学位论文 光催化降解和光降解氯代乙酸的研究 摘要 氯代乙酸是一类具有很高致癌风险的氯化消毒副产物，其中的二氯乙酸和三 氯乙酸是构成饮用水消毒副产物致癌风险的主要物质。针对氯代乙酸给饮用水带 来的不安全性，进行了光催化降解和光降解的研究。比较了两种降解方式的降解 效率。提出了光降解氯代乙酸可能的反应机理。推导出了降解过程的动力学方程。 考察了酸性初始条件和碱性初始条件对降解效率的影响。探索了降解过程中体系 pH值的变化规律。 结果表明，对于一氯乙酸和二氯乙酸，酸性初始条件和碱性初始条件下的光 催化降解效率均高于光降解的效率；而三氯乙酸却相反，酸性初始条件和碱性初 始条件下的光降解效率均高于光催化降解的效率。在光降解氯代乙酸的过程中， 水合电子起了重要作用，可能的降解机理是水合电子引起的自由基反应机理。光 催化降解和光降解氯代乙酸均符合一级反应动力学过程。不同的酸碱性初始条件 对光催化降解和光降解氯代乙酸均有影响，酸性初始条件有利于降解反应的进 行。光催化降解和光降解过程中体系的pH值均会不断变化并呈现逐渐降低的趋 势。通过实验可以看出，光降解法对氯代乙酸也有较好的去除效果，并且较之于 光催化方法更加便宜、方便。这一研究工作将为降低饮用水中消毒副产物提供新 的思路和途径。 关键词：光催化降解；光降解：氯代乙酸；消毒副产物；反应机理；pH值 兰州大学硕士学位论文 兰州大学硕士学位论文 光催化降解和光降解氯代乙酸的研究 Abstract Chloroacetic acids ale one class of disinfection by·products with hi曲carcinogenic risk．And the Dichloroacetic Acid and Trichloroacetic Acid are the main carcinogenic risk substances．n硷researches of photocatalytic degradation and photolytic degradation of chloroacetic acids have been studied due to their unsafety to the drinking water．There is a conversion efficiency comparison about the two degradation methods．111e possible reaction mechanisms of the photolytic degradation of chioroacctic acids are proposed．The kinetic equations of the degradation processes are educed．111e effects of the acid@and alkaline initial condition to the conversion efficiency ale concerned．，n圮variation rules ofpH values arc explored． It has been shown that the photocatalytic degradation conversion efficiency of Monochloroacetic Acid and Dichloroacetic Acid are botll higher than photolytic degradation,but for Trichloroacetic Acid the photocatalytic degradation conversion efficiency is lower than photolytic degradation．nle aqueous electrons play an important role in the photolytic degradation of chloroacetic acids processes，and the possible reaction mechanisms are the free radical reactions aroused by the aqueous electron．nle study confirmed that the kinetic equation of photocatalytic degradation and photolytic degradation of chloroacetic acids processes are bo