Abstract
It's reported that the trihalomethane was produced from the 1,3-diketone structural compounds such as acetylacetone by chlorination for water supply, and the water treatment methods should be necessary to prevent their production. In this report, each 5 mM diketone was treated by ozone alone, UV irradiation alone or ozone + UV irradiation (ozone/UV), and their degradation pathways were investigated from the decomposition products.
The main pathway of diketone was considered to have released a longer side-chain prior to the other shorter chain for the one side ketone group. The released groups were oxidized to keto-aldehydes and keto acids. When the shorter side-chain was methyl group, the residue group was oxidized to acetic acid. In the side pathway, a small quantity of keto acids was produced from the residue group when the methyl group as a shorter side-chain was released as formaldehyde.
The decomposition behaviors of three diketones themselves by ozone/UV were compared, and acetylacetone was decomposed most rapidly among them. Acetylacetone was decomposed comparatively rapidly even by UV irradiation alone, as it has UV absorption spectrum at about 254 nm which is the main irradiation wavelength of low pressure mercury lamp.
TOC (total organic carbon) removal(%) was very high by ozone + UV irradiation, and most efficient decomposition to inorganic carbon dioxide compared with ozone alone treatment was assumed.
