No abstract

No abstract

In this study, UV/oxidant and UV/TiO 2 /oxidant systems were employed to treat textile wastewater. The parent compound was C.I. reactive red 198 (RR198). The selected oxidants were H 2 O 2 , Na 2 S 2 O 8 , NaBrO 3 , and NaIO 4 . The effects of oxidant dosage (1-24 mM), wavelength of UV (254 and 365 nm) and radical scavenger addition (C 2 H 5 OH) were determined in UV/oxidant systems. The experimental results revealed that all oxidants effectively decolorized RR198 under 254 nm irradiation; however, only Na 2 S 2 O 8 and NaIO 4 can decolorize RR198 under 365 nm irradiation. The decolorization rates fit a pseudo-first order reaction model. Under 254 nm irradiation and 6 mM oxidant addition, the decolorization rate constants (k) of H 2 O 2 , Na 2 S 2 O 8 , NaBrO 3 , and NaIO 4 for RR198 were 10.24, 17.93, 13.37, and 11.90 h -1 . Under 365 nm irradiation, 1 g/L TiO 2 and 1 mM NaIO 4 addition, the k values of the UV/TiO 2 , UV/NaIO 4 , and UV/TiO 2 /NaIO 4 systems were 0.50, 0.52, and 11.67 h -1 . The inhibition of RR198 decolorization by the addition ethanol indicates that the primary decolorization pathway involves hydroxyl radicals in UV/H 2 O 2 and UV/Na 2 S 2 O 8 systems, and that oxidation by other radicals is probably important in UV/NaBrO 3 and UV/NaIO 4 systems.

No abstract