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

T. Alapi, K. Van Craeynest, H. Van Langenhoeve, J. Dewulf, A. Dombi

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

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 {radical dot}Cl formed during the direct photolysis of the target substances. The relative contributions of direct photolysis and {radical dot}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 {radical dot}Cl concentration, whereas the addition of CH2Cl2 to CHCl3 decreased its degradation rate, suggesting that CH2Cl2 acts as a {radical dot}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 {radical dot}Cl-sensitized reactions and direct photolysis.

Original languageEnglish
Pages (from-to)139-144
Number of pages6
JournalChemosphere
Volume66
Issue number1
DOIs
Publication statusPublished - Jan 2007

Keywords

  • 184.9 nm VUV light
  • Chlorine radical reaction
  • Direct photolysis
  • Low-pressure mercury lamp

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

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