Degradation of organic pollutants by ultraviolet/ozone in high salinity condition: Non-radical pathway dominated by singlet oxygen.

In this work, the combined ultraviolet ozone process (UV/O) was applied for organic contaminant (Reactive Blue K-GL, RB) degradation in high salinity. The degradation rates of RB in both O and UV/O systems were enhanced by NaCl (the k increased from 0.080 to 0.116 to 0.132 and 0.267 min respectively), while mineralization rate varied at different salt conditions. In addition, UV irradiation promoted the degradation efficiency of RB with the presence of salt. Singlet oxygen (O) was the primary active species in the UV/O system. The quenching experiments and signal intensity of O corresponded well to the mineralization of RB. Under conditions of high salinity and high pH, O has high mass transfer coefficient (k, 3.303 min) and self-decomposition (k, 0.600 min), which further promoted the formation of O for mineralization of RB. Furthermore, UV/O system was efficient in real textile wastewater treatment (COD removal rate 91.7% and decolorization rate 98.7%).