Photocatalytic degradation of pentachlorophenol on titanium dioxide particles: identification of intermediates and mechanism of reaction

Solar-Powered Photocatalytic Fiber-Optic Cable Reactor for Waste Stream Remediation

“…The higher initial reaction rate and faster time to complete degradation for the-OFR2 outdoor experiment is due to the higher absorbed light intensity, 25-41, compared to 10 µE L-1 min-1 • The OFR2 performed comparably to the OFRl but achieved higher relative quantum efficiencies for both the indoor and outdoor irradiations. A relative quantum efficiency of¢ = 0.020 was achieved for the indoor OFR2 experiment which is comparable to previously reported values for the photocatalytic oxidation of 4CP (Barbeni et al, 1985;Mills and Hoffmann, 1993;Hofstadler, 1994). The results of the 4CP oxidations using artificial and solar light are summarized in Table 1 A relative quantum efficiency range for the outdoor irradiatio:q of¢ = 0.01,7-0.010 was estimated based on an average UV flux of 30 ± 5 µE min -i for the one-hour irradiation period.…”

“…4CP has been reported to undergo hydroxyl radical insertion as an initial step in the overall oxidation Tseng and Huang, 1991;Mills and Hoffmann, 1993) according to the following generally accepted mechanism :…”

“…The capability of metal oxide semiconductor photocatalysts to degrade effectively a wide range of hydrocarbon contaminants has been well documented (Matthews, 1990;Fox and Dulay, 1993;Mills et al, 1993;Ollis and Al-Ekabi, 1993;Hoffmann et al, 1995). The solid photocatalyst is activated by ultraviolet light generating holes and excited electrons which combine with surface sorbed species such as water and oxygen to form highly reactive radical species '(e.g., OH· and o;-).…”

Effect of titanium dioxide nanoparticles on the bioavailability, metabolism, and toxicity of pentachlorophenol in zebrafish larvae

“…However, the photocatalytic degradation of PCP could occur in the presence of high n-TiO 2 concentrations (200 mg/L) under UV illumination condition (450 W), via generation of ROS (e.g., hydroxyl radical) to attack para position of the PCP ring to form a semiquinone radical, which in turn disproportionates to yield detected metabolic products (e.g., p-chloranil and tetrachlorohydroquinone) [37]. Likewise, there is ample evidence to indicate that photocatalytic degrade organic compounds are most likely driven by a UV-induced (especially at 300-388 nm) formation of ROS by n-TiO 2 [14,47,48].…”

“…2,3,4,6-tetrachlorophenol, 2,4,6-trichlorophenol, and 2,6-dichlorophenol) in water [37]. We measured PCP concentrations and the possible photocatalytic degradation products in exposure media.…”