Photodegradation of tefuryltrione in water under UV irradiation: Identification of transformation products and elucidation of photodegradation pathway.

Photodegradation is an important abiotic degradation process in the aquatic environment. In this study, the photodegradation of tefuryltrione in aqueous solution was investigated under UV-Visible irradiation. Effects of carbonate (CO32-), bicarbonate (HCO3-), nitrate (NO3-), hydrogen phosphate (HPO42-), potassium (K+), and ammonium (NH4+) on the photodegradation kinetics of tefuryltrione were evaluated. Results showed that tefuryltrione photodegradation was increased by HCO3-, CO32-, and NO3- in the range of 0.1-10 mmol L-1; decreased by HPO42-; and insignificantly affected by K+ and NH4+. Twelve main transformation products (TPs) were separated and identified on the basis of mass spectrum data assigned by elemental-composition calculations, comparison of structural analogs, and available literature. A tentative photodegradation pathway was further proposed depending on the identified TPs and their kinetic evolutions. Results indicated that TP 1 was generated by the hydroxyl that substituted for chlorine, TP 2 was formed by the cleavage of the ether bond of tefuryltrione, and TPs 3-6 were formed by the breakage of the CC bond of the keto moiety of tefuryltrione. Further, TPs 9-12 were formed by the rearrangement of tefuryltrione-photodegradation products. These findings are highly important for elucidating the environmental fate of tefuryltrione in aquatic ecosystems.