DECOLORIZATION AND DEGRADATION OF THE DYESTUFF C.I. DISPERSE BLUE 56 IN WASTEWATER BY UV/NaCIO/O2.

Decolorization and degradation of C. I. Disperse Blue 56 (DB 56) in aqueous dispersion by the methods of UV, NaCIO, and UV/NaCIO, respectively, has been investigated in the present study. It was found that the combination of UV/NaCIO is most efficient, and the color and chemical oxygen demand (COD) removal rate related to different methods decreased in the following order: UV/NaCIO > NaClO >>UV. The decolorization efficiency (99%) was always far higher than that of mineralization (49%) when the model dye solution was treated by UV/NaC1O for 60 mm. In order to address the possible formation of absorbable organic halides (AOX) arised from the use of NaCIO as an oxidant in the present study, DB-56 solution saturated with either O₂ or N₂ was treated by UV/NaCIO to explore the optimum conditions to minimize the generation of AOX species. The results revealed that AOX species were non-detectable in the UV/NaCIO/O₂ system after 60 mm reaction, whereas for UV/NaCIO/N₂ system, a fairly large number of AOX was detected by GC/MS. [ABSTRACT FROM AUTHOR]