Direct VUV photolysis of chlorinated methanes and their mixtures in a nitrogen stream

被引：20

作者：

Alapi, T.

Van Craeynest, K.

Van Langenhoeve, H.

Dewulf, J.

Dombi, A.

机构：

[1] Univ Szeged, Dept Inorgan & Analyt Chem, H-6701 Szeged, Hungary

[2] Univ Ghent, Fac Agr & Appl Biol Sci, Dept Organ Chem, EnVOC,Res Grp Environm Organ Chem, B-9000 Ghent, Belgium

来源：

CHEMOSPHERE | 2007年 / 66卷 / 01期

基金：

匈牙利科学研究基金会; 美国国家科学基金会;

关键词：

184.9 nm VUV light; chlorine radical reaction; direct photolysis; low-pressure mercury lamp;

D O I：

10.1016/j.chemosphere.2006.04.090

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

The gas-phase decomposition of CCl4, CHCl3 and CH2Cl2 and their binary mixtures was studied in a flow-type reactor in a nitrogen gas stream, using a low-pressure mercury vapour lamp covered with a high-purity silica quartz sleeve. The 184.9 nm vacuum-ultraviolet (VUV) light emitted is able to rupture the C-Cl bond in these target substances. For H-containing compounds, the decomposition takes place not only by direct photolysis, but also by H abstraction by Cl-. formed during the direct photolysis of the target substances. The relative contributions of direct photolysis and Cl-.-sensitized reactions to the decomposition were estimated at different initial concentrations. The addition of CCl4 to CHCl3 or CH2Cl2 increased their decomposition rates via increase of the Cl-. concentration, whereas the addition of CH2Cl2 to CHCl3 decreased its degradation rate, suggesting that CH2Cl2 acts as a Cl-. radical scavenger. The variation of the product distribution confirms the effect of the composition of the irradiated gas mixtures on the relative contributions of Cl-.-sensitized reactions and direct photolysis. (c) 2006 Elsevier Ltd. All rights reserved.

引用

页码：139 / 144

页数：6