Non-degradable triazine substrates of atrazine and cyanuric acid hydrothermally and in supercritical water under the UV-illuminated photocatalytic cooperation

Strong oxidation by titanium dioxide photocatalysis can occur by photodegradation of organic contaminants in air and water. Some endocrine disruptors such as 2,4-dichlorophenoxy acetic acid (Chamarro and Esplugas, 1993; Pichat et al., 1993; Muller et al., 1998; Modestov and Lev, 1998), 2,4-dichlorophenol ( Al-Ekabi and Serpone, 1988; D and D; Lee et al., 1992; Ku and Hsieh, 1992), nonylphenol ( Hidaka et al., 1990; Horikoshi et al., 2000), bisphenol A ( Barbeni et al., 1987), diethyl phthalate ( Sundstrom et al., 1989; Watanabe et al., 2003), etc. which can be neither biodegraded by bacteria nor degraded thermally can be degraded by TiO2 photocatalytic treatment. However, incomplete photomineralization partly occurred, when TiO2 photocatalytic degradation is employed for the treatment of certain endocrine disruptors. For example, no atrazine pesticide having triazine skeleton can be completely mineralized even by a photocatalytic procedure; the photodegradation of atrazine ultimately stops at the intermediate step of cyanuric acid, which cannot be photodegraded even after long illumination times (Pelizzetti et al., 1990).