Advanced oxidation of acid yellow 11 dye; detoxification and degradation mechanism

Abstract

Acid Yellow 11 (AY-11) is a toxicant azo dye discharged into the aquatic environment from textile, leather, food, and paper industries. This manuscript demonstrates the oxidation processes of AY-11 by ozone (O3) and ultraviolet (UV) assisted ozonation for decolorization and detoxification. Parameters affecting the performance of AY-11 decolorization process were optimized. The results revealed that the initial dye concentration and pH were effective parameters controlling the decolorization performance. More than 99% of decolorization was obtained within the first 20 min of the ozonation process at 100 µg/mL AY-11 dye and pH 9. The decolorization of AY-11 by O3/UV was slightly less efficient than the individual use of O3 in terms of chemical oxygen demand and color removal. Kinetics analysis indicated that AY-11 dye decolorization followed the pseudo-second order. The final degradation products of AY-11 dye in wastewater were identified using GC-MS. The AY-11 dye degradation intermediates were identified using LC-ESI-MS/MS. The toxicity test on the zooplankton of the treated aqueous solution indicated that the O3 and O3/UV treatments reduced the toxicity effect.