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多氯代二苯并呋喃(PCDFs)是持久性有机污染物之一,其光化学降解是其主要的环境降解途径,本文是采用量子化学方法对PCDFs光解性质进行研究。本文采取AM1半经验量子化学计算方法计算了所有135种PCDFs的生成热和前线分子轨道能量,据此讨论了PCDFs分子光激发和还原脱氯难易程度与分子结构之间的关系。结果表明生成热可以成功解释PCDFs在水相中随着分子氯取代数目增加而光解速率降低的规律,而前线分子轨道能则可以解释正构烷烃溶剂中随氯原子取代数目增加而还原脱氯在降解机理中越占主导地位的规律,从而从量子化学的角度为实验结果提供了理论解释。
Polychlorinated dibenzofurans (PCDFs) are one of the persistent organic pollutants. Their photochemical degradation is the main pathway of environmental degradation. In this paper, the photochemical properties of PCDFs are studied by using quantum chemistry method. In this paper, the heat of formation and frontier molecular orbital energies of all 135 PCDFs were calculated by semi-empirical quantum chemical method (AM1). The relationship between the degree of molecular photo-induced and reductive dechlorination of PCDFs and molecular structure was discussed. The results show that the heat generation can successfully explain the photodegradation rate of PCDFs in the aqueous phase with the increase of molecular chlorine substitution, while the frontier molecular orbital energy can explain the dechlorination of n-alkanes with the increase of the substitution number of chlorine atoms The more dominant the law in the degradation mechanism, thus providing a theoretical explanation for the experimental results from the perspective of quantum chemistry.