Effects of quinones on free-radical processes of oxidation and fragmentation of hydroxyl-containing organic compounds

Route of glycerol conversion and product generation via TiO2-induced photocatalytic oxidation in the presence of H2O2

“…3(b), no induction period of glycerol conversion and product generation was observed in this system, suggesting that the generated HO Å radicals had more oxidizing power than the photogenerated holes. With regard to product selectivity, the selectively of DHA was observed at around 10% during the first 4 h and dropped slightly to 1.09% at 8 h. This might be attributed to the preferential attachment of the HO Å radicals at the primary C atom of glycerol [42,43] or the rearrangement of DHA to GCD, which was clearly shown by a high selectivity of GCD compared with that of DHA. Although a high selectivity of GCD was observed at the early period of experiment, a drastic drop occurred along the irradiation time.…”

A study of catalytic behaviour of aromatic additives on the photo-Fenton degradation of phenol red

“…26 Effect of fulvic acid on Fe (II) oxidation by hydrogen peroxide has been studied by Voelker and Sulzberger. 27 The effect of quinones on the free radical processes of oxidation and fragmentation of hydroxylcontaining organic compounds has been investigated by Shadyro et al 28 In the present work, the effect of various organic additives on the rate of photoFenton degradation of phenol red was investigated and the main emphasis is given to determine the conditions where these additives show the maximum rate of reaction. An attempt has also been made to explain their catalytic behaviour.…”

Photocatalytic conversion of glycerol to dihydroxyacetone

“…At this stage, it might be implied that DHA can be also rearranged to form GCD or oxidized to GCA via h + -mediated oxidation with selectivity ratio (S GCD /S DHA ) of 2.5:1. generation was observed in this system, suggesting that the generated OH  radicals had more oxidizing power than the photogenerated h + . With regard to product selectivity, the selectively of DHA was observed at around 10% during the first 4 h of irradiation time and slightly decreased to 1.09% at 8 h. This might be attributed to the preferential attachment of the OH  radicals at the primary C atom of glycerol [147,148] or the rearrangement of DHA to GCD, which was clearly shown by a high selectivity of GCD compared with that of DHA. Although a high selectivity of GCD was observed at the early period of experiment, a drastic drop occurred along the irradiation time.…”