| Ultraviolet filters (UVFs) are used in a variety of personal care products, including sunscreens and cosmetics, to protect against ultraviolet (UV) radiation. Three of the most commonly employed UVFs are oxybenzone (OXY), octocrylene (OC), and octinoxate (OMC). While these compounds provide protection against harmful UV radiation, they also represent a unique human and ecological health risk. To address these concerns, ozone application to UVFs in water and wastewater matrices was carried out and transformation efficiency was calculated. Transformation efficiency varied with water/wastewater quality. For example, an applied ozone dose of 6 mol O3/mol OXY transformed approximately 62, 44, 23, and 13% of OXY in DI water, surface water, wastewater effluent, and raw wastewater, respectively. Second order rate constants were measured for UVF reaction with ozone; reactivity with ozone varied. Second-order rate constants for OXY (k"app,o3,OXY ) ranged from 3.65x102 to 1.68x10 6 M-1s-1; for OMC, k"o 3, OMC was 22(+/-2.14)x104 M -1s-1; and for OC, k"o3, OC was 1.56 (+/-0.18) M-1s-1. The characteristic UV absorbance of solutions containing UVFs was measured as a function of wavelength, pH, and treatment level providing innovative insight into ozone attack mechanisms and identification of transformation products. Several transformation products were identified for ozonation of OXY, OMC, and OC and the corresponding structures represent similar environmental concerns as the parent UVFs. |
