Several Rules for Treating Phenol Wastewater via Oxidation by O3/UV-formed Radicals1

The treatment of phenol wastewater with an ultraviolet source and an oxone generator by introducing salicylic acid as the capturer is described. The presence of HO˙ during the phenol degradation has been proved. The impacts of factors such as acidity and reaction time on the HO˙ formation are also discussed. The results demonstrate that HO˙ generated from ozone/UV oxidation under a basic condition is the immediate cause of phenol degradation. At room temperature and a pH value of 9.93, the degradation of phenol occurs rapidly within 0.5 min and the removal of phenol (100 mg/L) is above 98.5% within 15 min; in the meantime, the pH value declines gradually with the degradation of phenol. A discussion about the formation and the transformation of the intermediate products during phenol degradation is included.