Bezafibrate removal by coupling ozonation and photocatalysis: Effect of experimental conditions

Abstract

The pseudo-first order rate constants of bezafibrate (BZF) degradation by photocatalytic ozonation (PCO) in the presence of commercial TiO2, P25, were studied under different experimental conditions. Removal percentage of BZF was positively affected by the increase of ozone inlet concentration and catalyst amount, while initial pollutant concentration presented a negative influence. In addition to the importance of catalyst during BZF removal, its presence plays a crucial role in terms of mineralisation level, achieving a significant degradation of the intermediates in a short period of reaction. The BZF was mainly removed by direct reaction with molecular O3, regardless of the experimental conditions. In addition to the higher affinity of direct O3 reactions to remove BZF and the first by-products at pH 4.4, the adsorption capacity is enhanced due to BZF deprotonated form (pH > pKa) and the catalyst surface positively charged (pH < pHpzc).The estimated pseudo-first order rate constant revealed that BZF degradation is more inhibited by humic acid, especially at high concentrations, than tert-butanol, suggesting that HO radicals are not the main responsible for BZF decay.