The influence of plasma of crown discharge and ozone on the rate of photocatalytic oxidation of acetone and benzene vapors

Abstract

The influence of negatively polar plasma of crown discharge on the rate of photocatalytic oxidation (PCO) of vapors of acetone and benzene was investigated by studying dynamics of changes in the composition of gas-air mixture in a 404 L reactor using in-situ IR spectroscopy. Titanium (Hombifine N) was used as the photocatalyst; it was lighted with a UV-lamp at the wavelength λ = 365 nm. The rate of the photocatalytic oxidation of the substrate vapor was compared to the oxidation rate in crown discharge plasma, to the rate of dark oxidation with ozone (side product of the discharge burning), to the rate of photocatalytic oxidation in the presence of ozone, as well as to the rate of the photocatalytic oxidation under medium treatment with the crown discharge plasma. The rate of oxidation of various substrates was shown to be much lower in individual plasma and in ozone-containing atmosphere than in photocatalytic oxidation but application of the crown discharge led to an increase in the rate of photocatalytic oxidation and in the rate of oxidation in ozone-containing atmosphere. Under the action of the discharge, ozone was not accumulated in considerable proportion in the gas mixture but after consumption of 80–90 % of the oxidized substrate. The order of acetone PCO with respect to ozone was determined. It was shown that the action of plasma allowed benzene PCO to be noticeably accelerated due to considerable depression of the photocatalyst deactivation compared to that during individual PCO of benzene.