Ozone decomposition by ultraviolet ray. The relationship between the starting ozone concentration and decomposition ratio.

Abstract

Ozone decomposition capacity by ultraviolet ray from a low pressure mercury vapor quartz lamp was studied in order to purify the exhaust gas of photo oxidation apparatus. The lamp used in the experiments was made from a conventional quartz tube. A main spectral line is 253.7 nm in cylinder shaped 8 W lamps. Spectral lines of 200 nm or under are cut. By supplying the air containing constant concentration of ozone into an annular space of a double pipe structure, the relationship between the concentration of residual ozone and gas flow rate (0.025-10 l/min) were examined. In the measurement the starting concentration of ozone was changed into eight degrees (1, 3, 5, 7, 10, 30, 40, 75 ppm), keeping the exposing length of the lamp and the width of the annular space constant (105, 31 mm) in consideration of the influence on decomposition. In each starting ozone cencentration, when the flow rate was brought down, ozone began to decompose rapidly and then disappeared completely. In the case of high concentration, it began to decompose at a small flow rate, and the decreasing ratio was bigger than that of low concentration. In each concentration the relative formula between supplied gas quantity and the decomposition ratio on the log paper was obtained.