金属对催化还原DDT的降解产物及其反应机制的研究

本报告介绍DDT经金属对处理后降解产物的分析鉴定和有关反应机制的初步研究。 降解产物主要是用气相色谱—质谱联用分析鉴定的。水溶液中的DDT用Cu-Zn金属对还原其降解产物经鉴定是DDD、DDMS、DDE_t,它们是DDT分子脱去烷基碳原子上不同数目的氯原子的产物。而在Cu-Fe金属对作用下,水溶液中的DDT的还原则是同时得到四种不同类型的产物。它们是DDT脱去烷基碳原子上的1个和3个氯原子的DDD和DDE_t;DDT脱氯、氧化产物DBP和DBH;DDT脱去HCI生成的DDE;两个DDT分子二聚脱氯的产物TTTB和TTDB。 实验证明金属对对DDT的作用是催化还原反应,金属对起着催化剂和还原剂双重作用。通过实验结果对DDT在金属对作用下的反应机制进行了初步探讨。

INVESTIGATION OF THE DEGRADATION PRODUCTS AND THE REACTION. MECHANISM OF DDT WITH METAL COUPLES

All the degradation products were analyzed by identifying with GC-MS. The identified products of DDT with Cu-Zn couple in water were found to be DDD, DDMS, and DDEt. They are assumed to be resulted by loss of different numbers of chlorine atoms from the alkyl carbon atom of DDT molecule. In the case of DDT reaction with Cu-Fe couple, four different kinds of degradation compounds were found. Of these DDD and DDE_t are derived from DDT by losing 1 and 3 chlorine atoms respectively. DBP and DBH are the dechlorination and oxidation products of DDT, with DDE a dehydrochlorination product. TTTB is a dimer of DDT molecule, and is the major product of this reaction,while TTDB may also be formed simultaneously with TTTB.Our experiments show that the reaction of DDT with metal couple is a catalytic reduction reaction. The metal couples act both as a reducing agent and as a catalyst during reduction of DDT. The possible reaction mechanism of DDT with metal couple was also discussed.