Abstract：Azo dyestuff in effluent forms composite pollutants. The composite wastewater is persistent in color and nonbiodegradable. Methyl orange with typical azo structure was used to simulate wastewater. The degradation of methyl orange with free radical was studied. The effects of pH, initial methyl orange concentration, free radical concentration, temperature and reaction time on the degradation of methyl orange were discussed. The acidity is favorable for degradation of methyl orange. The results indicated that the COD removal ratio and decolorization ratio of 200 mg/L methyl orange reached to 86. 87% and 88.53% within 3 minutes when pH was 1.5. Compared With the changes of absorption spectra of methyl orange before and after treatment, it showed that the azo bond and benzene ring were damaged after the degradation by free radicals, and most of methyl orange elements were oxidized and decomposed
2010, Vol. 31 
