Selectivity of hydroxyl radical in the partial oxidation of aromatic compounds in heterogeneous photocatalysis

Influence of water temperature on the photocatalytic activity of titanium dioxide

“…The role of hydroxyl radicals in the organic pollutant decomposition process was studied by Peiró et al [14], Vione et al [15] and Palmisano et al [16]. Peiró et al [14] concluded that during phenol decomposition,…”

“…Nevertheless, phenol oxidation occurred by means of • OH radicals, while benzoic acid molecules were decomposed on the surface of TiO 2 by means of adsorbed hydroxyl radicals. Palmisano et al [16] investigated the selectivity of hydroxyl radicals in the partial oxidation of aromatic compounds: nitrobenzene, cyanobenzene, benzoic acid, phenol, 4-chlorophenol, Nphenylacetamide, phenylamine and 1-phenylethanone. They concluded that in the case of pollutants containing an electron donor group, it is possible to observe the OH radicals attack obtaining two kinds of substitution in ortho-and para-positions.…”

Review: Photocatalytic Degradation of Textile Azo Dyes

“…During Photocatalytic oxidation the concentration of organic substrate over time is depend upon photonic efficiency [29] . At high substrate concentration however, the photonic efficiency diminishes and the titanium dioxide surface becomes saturated leading to catalyst deactivation [30] .…”

Water Reclamation by Heterogeneous Photocatalysis over Titanium Dioxide

“…The determination of an optimal organic loading for a given photoreactor is essential to ensure effective operational conditions. Palmisano et al (2007) have reported that organic molecules with electron withdrawing group adsorb better than molecules with electron donating groups. It was also shown that organics with complex molecular formulae (4-chlorophenol, humic acid, etc.)…”

“…It was also shown that organics with complex molecular formulae (4-chlorophenol, humic acid, etc.) break down to various intermediate products before final mineralisation that have different adsorption affinities toward the photocatalyst than the original pollutant (Palmisano et al 2007). In contrast, simple compounds such as oxalic acid have been reported to undergo direct mineralisation to CO2 and H2O (Bahnemann 2004).…”