Research The Mechanism Of Modified ACF To Promote Anaerobic Degradation Of Azo Dyes

Treating textile-processing wastewater cause a widely concern by the industry because of its high chromaticity, high toxicity and biological refactory,;Azo dyes are the most common poisonous and biodegradable organic pollutants; Currently anaerobic / aerobic process has been widely used for the treatment of azo dyes, and the anaerobic stage is usually the controlled step of the process. Therefore,it is the key issue of the current study to improve the anaerobic degradation rate. Present study suggests that commercial activated carbon（AC） surface containing quinoid structure can be used as a redox mediator to accelerate anaerobic degradation of azo dyes, and may be modified to enhance its catalytic activity. This paper intends to modifiy activated carbon fiber（ACF） which has similar structure with activated carbon to increase its surface quinone group content,and explore the role of modified ACF to accelerate the degradation rate of azo dyes and the mechanism and kinetics of modified ACF to promote anaerobic degradation of azo dyes.In this paper, we use HNO₃ and H₂O₂ on ACF oxidative modification. The AC,ACF and modified ACF were characterized.It is showed that ACF has greater specific surface area and average pore diameter and surface quinone group content than AC, and ACF specific surface area and average pore diameter decreases with modification prolonged, while quinone group content increases with modification prolonged. Using glucose as the electron donor, the biological decoloriation of zao dyes（methyl orange） was conducted in a series of batch experiments at p H=7 and T= 37.5℃. The application of ACF, NOF₂ and HOF₂ in bioreactors improve the decolorization rate to 1.53,1.82 and 2.10 times of the anaerobic decolorization rate within 4.0h,and the rate of removal of methyl orange due to catalysis were AC’s 4.33,7.11 and 7.33 times. The degradation process are in line with first-order kinetics. By ACF and modified ACF adsorption capacity and UV- visible spectral scanning spectrophotometry,we vertified that ACF and modified ACF can accelerate the biodegradation process of methyl orange dyes as a redox mediator, and the catalytic activity of ACF and modified ACF was stronger than AC.The chemical reduction of methyl orange with Na2 S shows that ACF and modified ACF can promote the chemical reduction rate, and the degradation process are in line with first-order kinetics. The anaerobic decolorization and degradation of azo dye wastewater is the combined effect of biological and chemical reduction. Under anaerobic conditions, ACF and modified ACF can promote the degradation rate of methyl orange dyes as a redox mediator, their electron transfer capability and surface quinone group content is much the same. These two experiments show that ACF and modified ACF can be used as a redox mediator to accelerate degradation rate by transferring electron from substrate to azo dyes, in result of increasing the decolorization rate.