Influence of water matrix on benzophenone degradation by UV irradiation

This study presents the results from a bench-scale UV irradiation experiment of benzophenone (BP) in different water matrices. Despite the reported recalcitrance of BP to UV-irradiation, it was successfully degraded in solution when intensively irradiated by UV light in a batch reactor for 4 h. In this way, it was possible to remove 56 % and 45 % of 1 µg·L -1 and 10 µg·L -1 of BP in MilliQ water, respectively. The addition of a mixture of anions suppressed the degradation of BP at the lower concentration level by 20 %. The addition of a dissolved organic carbon (DOC) surrogate mixture (molar ratio DOC:BP=3000:1) increased the degradation of BP in MilliQ water (removal 80 %). At 1 µg·L -1 of BP and 1 mg·L -1 of DOC, removal was 70 %, while at 10 µg·L -1 of BP and 10 mg·L -1 of DOC, there was no observable difference in removal compared with removal in MilliQ water. The results show that both DOC and anions influence the photodegradation of BP. Furthermore, it was shown that removal efficiency depends on the concentration of BP. These findings show the importance of a detailed characterisation of the water matrix in studies relating to the fate of micropollutants during UV irradiation.