Toluene and 4-chlorotoluene decomposition in air mixture in electron beam generated non-thermal plasma reactor and their by-products identification

Degradation of toluene and 4-chlorotoluene in air mixture was studied by using electron beam generated plasma reactor. It was found that removal efficiency of toluene and 4-chlorotoluene was influenced by radiation dose, i.e. energy deposited in the gas, and their initial concentration. The by-products formed as a result of degradation of toluene or 4-chlorotoluene under electron beam radiation were identified. The mechanism of their degradation was proposed.
- OH radicals play a main role in degradation process of toluene or 4-chlorotoluene. For degradation of 4-chlorotoluene, reaction of
- OH radicals with 4-chlorotoluene by hydrogen abstraction from the methyl group, followed by peroxyl radical formation, is a main reaction pathway. 4-chlorobenzaldehyde and 4-chlorobenzyl alcohol are formed according to the Russel-mechanism. For degradation of toluene, reaction pathway of
- OH radicals with toluene by hydrogen abstraction from the methyl group plays an important role. Besides it, there are the other two important reaction pathways. One is reaction of
- OH radical addition and H atom abstraction from benzene ring; the other is
- OH-adduct reaction. Cresol, nitrotoluene and ring cleavage products are formed from these two reaction pathways. Since Cl is more electronegative than H, H atom abstraction from -CH3 by
- OH radicals from toluene (HC6H4CH3) is easier than from 4-chlorotoluene (ClC6H4CH3), this may explain why the decomposition efficiency of toluene is slightly higher than that of 4-chlorotoluene in an air mixture under EB radiation.