Effects of methanol, formamide, acetone and acetate ions on phenol disappearance rate and aromatic products in UV-irradiated TIO2 aqueous suspensions

Effects of methanol, formamide, acetone and acetate ions on the TiO2 photocatalytic degradation of phenol in water at equal initial concentrations ( 1 mmol L−1) have been studied. The amount of phenol adsorbed in the dark and the apparent first-order rate constant of phenol disappearance remained the same within experimental accuracy. The temporal variations in the concentrations of hydroquinone and catechol, the two main primary intermediate products, were not significantly affected either, except by acetate ions which increased these concentrations, particularly that of catechol. In the presence of each of the aliphatic additives, the phenol-phenol coupling products were less numerous and their lifetime was decreased. Traces of products showing reactions between phenol and acetate were found. Interpretations are tentatively presented for these observations. Overall, the absence of marked effects of these aliphatic pollutants upon phenol degradation are of great interest for the photocatalytic treatment of water, since these aliphatics represent intermediate products in the mineralization of organic matter.