Decolorization and detoxification of acid orange 7 by zero-valent iron with UV light

The decolorization and detoxification of acid orange 7 (ao7),a commonly used azo dye,by zero-valent iron (fe0) and uv light was investigated. the influence of important reaction parameters,such as initial ph and the fe0 dosage,on the color removal and effluent toxicity,was elucidated. results indicated that the decolorization of ao7 was enhanced in the uv/fe0 system,as compared to that with only uv or fe0,in which the decolorization efficiency in 60 min increased with increasing fe0 dosage and decreasing solution ph. the kinetics of the ao7 removal conformed to the langmuir-hinshelwood model with high correlation coefficient (r2 = 0.9962). under the optimum conditions,ao7 was decolorized rapidly within 60 min (over 97% decolorization efficiency),with 34.8% of toc reduction. fe0 could be used for repeated cycles to decolorize ao7 effectively. furthermore,nearly no daphnia magna immobilization was found after the treatment,suggesting that the method was effective to reduce the ao7 toxicity.