双频超声辐射协同H_2O_2降解偶氮染料废水的研究

采用双频超声协同H2O2降解酸性绿20染料废水,考察超声功率密度、染料初始浓度和pH、饱和气体及H2O2投加量等因素对酸性绿20降解效果的影响,结果表明,在给定实验条件下,双频降解效果优于单频超声波,且降解率随超声功率密度的增大而增大。酸性条件有利于酸性绿20的降解,当染料废水初始pH=4可取得最佳的降解效果;酸性绿20的降解效率随染料初始浓度的增大而降低,其优化初始浓度为40 mg/L。在反应体系中通入空气并投加H2O2,可取得最佳的降解效果。在优化实验条件下,采用双频超声协同H2O2降解5 h,酸性绿20的色度和TOC去除率分别为94.6%和36.3%;分析降解前后的紫外-可见光谱图可知,酸性绿20并非完全被降解为CO2和H2O,而是生成一些小分子有机中间体。

Degradation of azo dye wastewater by dual-frequency ultrasound synergized with H_2O_2

The degradation of azo dye Acid Green 20 was studied by dual-frequency ultrasound in the presence of H2O2.The effects of ultrasonic power density,initial concentration and pH of dyestuff solution,bubbling gas and H2O2 addition on degradation of Acid Green 20 were investigated.The results show that degradation efficiency at dual-frequency ultrasound mode is proved to be superior to that at single frequency mode under the given experimental conditions.Degradation efficiency increases with increasing ultrasonic power density.The degradation rate of Acid Green 20 is highly dependent on pH value and acidic condition helps to promote the degradation of Acid Green 20.The optimum degradation rate of Acid Green 20 can be achieved when pH value is 4.0.However,the degradation rate decreases with the increase of dye initial concentration and the optimal concentration 40 mg/L.Degradation rate of Acid Green 20 is enhanced significantly in the presence of saturated gases and H2O2.Although 94.6% of decolorization is achieved after 5 h degradation under the optimum conditions,Acid Green 20 is not completely mineralized to CO2 and H2O,instead,some organic intermediates are produced.