Decolorization of chloromethane and azo dyes mixed wastewater by ultrasound
氯甲烷与偶氮染料混合废水的超声脱色

The decolorization of azo dyes (including methyl orange and eriochrome black T) and methyl chloride (including CCl4, CHCl3 and CH2Cl2) simulated wastewaters by using 40 kHz ultrasound was studied. The effect of initial chloromethane concentration on azo dyes decolorization and TOC removal of sonication was investigated. The results showed that the ultrasonic decolorization rates of azo dyes were very slow. The ultrasound could make azo dyes to colorless in a short time in the presence of CCl4 and CHCl3, but had less effect of its TOC ultrasonic removal. The sonochemical decolorization of azo dyes was very poor in the presence of CH2Cl2. When the initial eriochrome black T concentration was 24 mg/L, the ultrasonic intensity was 0.392 W/cm2, the initial concentration of CCl4 and CHCl3 was 6.22 mmol/L and 8.30 mmol/L, the 20 min decolorization rate reached 90.86%, but the corresponding TOC removal rate was only 22.72% and 17.76%. Under the same conditions, the treatment effect of methyl orange was slightly superior than eriochrome black T.