Identification of mechanisms for decomposition of air pollutants by non-thermal plasma processing

TLDR

Non‑thermal plasma processing effectively treats dilute pollutants in large‑volume atmospheric‑pressure air streams, and understanding which plasma species drive decomposition informs reactor power requirements, initial reaction pathways, and scaling to commercial units. This study aims to identify the main reactions responsible for decomposing four representative compounds—carbon tetrachloride, methylene chloride, trichloroethylene, and methanol—using basic experimental and theoretical investigations. The authors performed basic experimental and theoretical studies to determine the plasma species responsible for each compound’s decomposition. The compounds are decomposed by distinct plasma species: electrons for carbon tetrachloride, nitrogen atoms for methylene chloride, oxygen radicals for trichloroethylene, and positive ions for methanol.

Abstract

Non-thermal plasma processing methods have been shown to be effective for treating dilute concentrations of pollutants in large-volume atmospheric-pressure air streams. This paper presents results from basic experimental and theoretical studies aimed at identifying the main reactions responsible for the decomposition of four representative compounds: carbon tetrachloride, methylene chloride, trichloroethylene and methanol. Each of these compounds is shown to be decomposed by a different plasma species: electrons, nitrogen atoms, oxygen radicals and positive ions, respectively. By understanding what plasma species is responsible for the decomposition of a pollutant molecule, it is possible to establish the electrical power requirements of the plasma reactor and help identify the initial reactions that lead to the subsequent process chemistry. These studies are essential for predicting the scaling of the process to commercial size units.