Pulsed-plasma destruction of phenol in an aqueous solution

An aqueous solution of phenol is exposed to pulsed-discharge plasma, and the decomposition characteristics of phenol are investigated for the different composition of a background gas. It is likely that OH radicals, produced by the collision between water vapour and energetic electrons in the pulsed plasma creeping on a water surface, are responsible for the decomposition of phenol in the solution for all kind of background gases. It is probably that OH radicals, produced by N$_{2}$ molecules excited in metastable state (N$_{2}(A^{3}\Sigma _{u}^{+}))$, and O$_{3}$ assist the phenol decomposition in pure N$_{2}$ and in pure O$_{2}$, respectively. In N$_{2}$-O$_{2}$ mixture, the decomposition rates of phenol stay at lower values, since NO$_{x}$ reduces O$_{3}$ concentration and inhibits the O$_{3}$ production. In Ar-O$_{2}$ mixture, the decomposition rate of phenol increases with an increase of Ar mixture-ratio; therefore, Ar atoms excited in metastable states (Ar(4$^{3}$P$_{2})$, Ar(4$^{3}$P$_{0}))$ are responsible for the decomposition of phenol at higher mixture ratio of Ar.