摘要
利用激光闪光光解技术研究了水相中四氯化碳光分解和光氧化的微观机制,并且指证了水相中四氯化碳受光激发所产生的瞬态光谱中的一些瞬态物种的特征吸收峰.并对这些瞬态物种的行为和归宿进行了研究.研究表明在248nm激光作用下,四氯化碳受光激发将分解为CCl_3自由基和Cl自由基.CCl_3自由基在无氧/有氧条件下的反应途径是不同的:在无氧条件下CCl_3自由基将进行偶合反应生成更难于降解的C_2Cl_6;而在有氧条件下CCl_3自由基则与O_2反应生成CCl_3O_2自由基,而CCl_3O_2自由基最终转变为COCl_2,这意味着光氧化能够有效地降解CCl_4.Cl自由基基本上不受氧气存在的影响,其归宿是与水分子发生电荷转移反应.
The dechlorinating microscopic mechanism and transient spectra of aqueous CCl4 was studied by using nanosecond laser flash photolysis (LFP). The transient absorption band (λmax < 300nm) of aqueous CCl4 solution deaerated by N2 was attributed to trichloromethyl radical ( CCl3 ) which decayed following 2nd - order kinetics with (2k/εl) equal to 6. 34×106s-1, and the transient absorption band (λmax < 320nm) of same solution deaerated by 02 was attributed to peroxytrichloromethyl radical (CCl3O2 ) which decayed following 1st - order reaction kinetics with a rate constant of 1.9×104s-1. The transient absorption band around 330nm was attributed to solvated chlorine atom. C2Cl6 as photolysis product of aqueous CCl4 solution without oxygen showed that CCl4 cannot be degraded by photolysis and free radical hydrolysis process. COCl2 as photolysis product of aqueous CCl4 solution in the presence of oxygen was observed directly in the transient absorption spectra, which means that CCl4 can be degraded by photooxidation process.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1999年第10期1081-1087,共7页
Acta Chimica Sinica
基金
国家自然科学基金(29777003)资助项目
关键词
水相
四氯化碳
激光闪光光解
降解
光降解
aqueous,CCl4,laser flash photolysis (LFP) ,transient absorption spectra,radical
