Degradation Of Azo Dye By Advanced Oxidation Process With Ultrasound Irradiation

Azo dyes,with high chromaticity,are difficult to degrade by traditional methods to meet the industrial emission standard,which become great threaten to the environment.Focus on the decoloration rate of Acid Red B,this research discusses the degradation efficiency of Acid Red B by advanced oxidation process and also carried out orthogonal experiments to study the effects of the addition of Fe₃O₄,the concentration of PMS,the ultrasound power,the ultrasound frequency,the initial concentration of Acid Red B and the initial p H of the solution.Single factor experiments were carried out to optimize the parameters in Fe₃O₄ activated PMS with ultrasound irradiation.Radical scavengers such as ethanol,tert-butyl alchohol and 1,4-benzoquinone were applied to investigate the key radicals in the system.Mineral salts such as Na H2PO4,Na HCO3 and Na Cl were added into the solution to study the effect of anions on the degradation of Acid Red B.Kinetic model and degradation pathway of the system were also illustrated in this paper.Finally,this method were applied to the industrial dye wastewater.The optimized operating parameters are Fe₃O₄ 1.0g/L,PMS 60mmol/L,ultrasound frequency 50 k Hz,ultrasound power 80 W.This method can be applied in a wide range of p H from 3.5 to 8.5.The catalyst was recycled for 3 times and the decoloration rate still remained above 95%.The results showed that sulfate radicals and the hydroxyl radicals played a key role in the system.The results indicated that H₂PO₄^-,HCO₃^- and Cl^- exerted a negative influence on the active radicals.Kinetics results fit well with first-order kinetics reaction.The conjugated system of the azo bond and naphthalene ring were degraded to small organic molecule firstly by sulfate radicals.As the reaction time passed by,the azo bond and naphthalene ring were removed completely and the sulfate radicals began to degrade the small organic molecule.After 90 min,they were also removed completely.The optimized parameters were applied to degrade industrial wastewater,the removal rate reached 85.5% after 90 min.