Ozone formation with (V)UV-enhanced dielectric barrier discharges in dry and humid gas mixtures of O2, N2/O2, and Ar/O2

The effect of (V)UV illumination at 172 nm and 253.7 nm on ozone formation with dielectric barrier discharges in air-like mixtures of nitrogen/oxygen and argon/oxygen as function of the water concentration is presented. Although (V)UV at these wavelengths efficiently cleaves ozone, the ozone concentration in a combined (V)UV/dielectric barrier discharge in oxygen-containing gases is reduced only very little. This corresponds to an enhanced concentration of atomic singlet oxygen, which, in presence of water, increases the production of hydroxyl radicals. This is confirmed by measurements of the removal rates of 2-propanol and of its byproducts in dry and humid air in a combined (V)UV/dielectric barrier discharge treatment.