Photocatalyzed degradations

Fig. 7. Photocatalyzed degradation of phenol showiag principal iatermediates including catechol [120-80-9] (1), hydroquiaoae [123-31 -9] (2), -beazoquiaoae [106-51-4] (3), pyrogaHol [87-66-1] (4), hydroxyhydroquiaoae [533-73-3] (5), and hydroxybenzoquiaone [2474-72-8] (6). The dashed lines...

Sanjuan A, Aguirre G, Alvaro M, Garcia H, Scaiano JC, Chretien MN, Focsaneanu K-S (2002) Product studies and laser flash photolysis of direct and 2,4,6-triphenylpyrylium-zeolite Y photocatalyzed degradation of fenvalerate. Photochem Photobiol Sci 1 955-959... 

S. Horikoshi. N. Serpone, Y. Hisamatsu, and H. Hidaka, Photocatalyzed Degradation of Polymers in Aqueous Semiconductor Suspensions, Environ. Set Technol. 1998,32, 4010. 

Xu Y, Langford CH. Variation of Langmuir adsorption constant determined for Ti02-photocatalyzed degradation. J Photochem Photobiol A Chem 2000 133 67-71. 

Dieckmann, M.S. Gray, K. A. Kamat, P. V. Photocatalyzed degradation of adsorbed nitrophenolic compounds on semiconductor surfaces, Wat. Sci. Tech. 1992,25,277. 

Goutailler G, Valette )-C, Guillard C, Paisse O, Faure R (2001) Photocatalyzed Degradation of Cyromazine in Aqueous Titanium Dioxide Suspensions Comparison with Photolysis, /. Photochem. Photobiol. A Chem. 141 79-84. 

Peiro AM, Ayllon JA, Peral J, Domenech X (2001) Ti02-Photocatalyzed Degradation of Phenol and ortfio-Substituted Phenolic Compounds, Appl. Catal. B Environ. 30 ... 

The difficulty of quantum yield determination in heterogeneous photocatalysis is related to reflection and scattering of UV/VlS radiation by suspended catalyst grains. Consequently, Serpone and Salinaro (1999) proposed a detailed protocol for the determination of photonic efficiencies (quantum yields) or relative photonic efficiencies, suggesting the photocatalyzed degradation of phenol as a standard reaction (using Ti02 as photocatalyst). 

Trillas, M., Pujol, M. and Domenech, X., 1996, Photocatalyzed degradation of phenol, 2,4-dichlorophenol, phenoxyacetic acid and 2,4-dichlorophenoxyacetic acid over supported TiOz in a flow system. J. Chem. Tech. Biotech., 67(3) 237-242. 

Figure 6.21 Photocatalyzed degradation of chloroform (initial concentration 122 ppm) in the presence of titanium oxide. I, illumination only II, catalyst only illumination plus catalyst. [Reproduced with permission from D. F. OUis, Environ. Sci. Technol, 19, 480 (1985). Copyright 1985, American Chemical Society.]...

Figure 6.22 Photocatalyzed degradation of carbon tetrachloride at pH 2.7 illustrating the role of propanol as an electron donor, (a), oxygenated b), deoxygenated. 0.5 g ...

Martin, G. P., Robinson, A. J., and Worsley, D.A. (2006) Hydrotalcite mineral stabilization of titanium dioxide photocatalyzed degradation of un-plasticized polyvinyl chloride,... 

Scheme 1. Primary events and intermediates in the photocatalyzed degradation of fluorophenols. Adapted from ref.[30].

Recently [32] photocatalyzed degradation of alkyl phenols and the nonionic nonylphenol ethoxylate were examined. Here the surfactant and alkyl phenols were susceptible to complete mineralization, as showed by the important demonstration of a carbon balance all the way to carbon dioxide (Fig.3) for polyethoxylated 4-nonylphenols with average numbers of 2, 5, and 12 ethoxy units. 

Three different studies of dissolved oxygen influence on the rate of photocatalyzed degradation have appeared [49-51], and all provide the same rate form. Adsorption of oxygen in a nondissociated form, on a separate site from that for hydrocarbon or halocarbon, would provide a rate function of the form... 

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