Investigation of the Chemical Nature and Possible Toxicity of Products Formed during the Ozone Disinfection of Drinking Water Containing Organic Substances

摘要

The potential for formation of carcinogenic epoxides of polycyclic aromatic hydrocarbons (3,4-benzopyrene and napthalene) in drinking water through action of ozone on their dissolved or suspended forms was explored. Within the limits of the techniques used, no conclusive evidence for epoxide formation from either compound was found; Ames bioassay produced no evidence for existence of their mutagenicity following ozone treatment. In addition, the ozonization of a model organic (phenol) in aqueous solution was studied using two approaches (ultraviolet (UV) light irradiation, and metal ion catalysts) for accelerating the rate of ozonolysis in aqueous solution. It was concluded that UV-induced ozone decomposition is responsible for photo-assisted ozonization, allowing for direct calculation of the light intensity needed to obtain a given degree of accelerated ozonization under specified conditions. Testing the catalytic ability of 25 transition metals and lanthanides revealed that vanadium pentoxide, uranium dioxide, and cobalt(II) catalyzed ozone decomposition, with the latter effectively tested for phenol ozonization. The results all indicate that aqueous phenol ozonization proceeds through initial ozone decomposition to a reactive species, for which the hydroxyl radical is proposed; this is in distinct contrast to established mechanisms in non-aqueous solution.