Hydroxyl Radicals Formation in Dielectric Barrier Discharge During Decomposition of Toluene

A method based on high performance liquid chromatography (HPLC), has been developed to measure hydroxyl radical (^·OH) in plasma reactors. The determination was performed indirectly by detecting the products of the reaction of ^·OH with salicylic acid (SAL). The applicability, and effect of time, specific input energy (SIE), relative humidity (RH), catalyst were investigated. It was found that 3 h was the optimal trapping time; concentration of ^·OH was (5.9–23.6) × 10¹³ radicals/cm³ at SIE range. The highest ^·OH yield and toluene removal efficiency (η) were achieved with a RH of 20%. With MnO _x , η was two times that without catalyst, while ^·OH yield in gas stream was one-sixth that without catalyst. However, if summed with ^·OH adsorbed on catalyst surface, the total ^·OH yield was the same as without catalyst. Experiments performed with/without toluene allowed to determine the role of ^·OH on decomposition of toluene in air plasma.