Yieldfactors for the formation of Oh radicals and hydrogen peroxide during the decomposition of aqueous ozone by pH-initiated chain reactions or by hydrogen peroxide or by uv irradiation

摘要

As has already been reported at the 8th Ozone World Congress (1987), ozone forms secondary oxidants when decomposed in water. The yield of the formaiton of OH radicals is mostly about 0.5, when Oh is produced for ma pH initiated chain reaction. These Oh radicals are the msot reactive and therefore unselective secondary oxidants. In most systems the yield for their production remains similar when the decomposition of ozone is accelerated by hydrogen peroxide, provided that the concentration of hydrogen peroxide relative to other scavengers is low enough not to scavange OH significnatly. Since 1987 we have improved oru possibilities to calibrate the chemical system for probing for Oh radicals by improving the use of the photolysis of H_2O_2 as a primary standard. This standard is much easier to apply than the high-energy radiation which also forms Oh radicals in a well known yield and has been used as our primary standard during earlier studies.