Decolourization of azo dyes using magnesium-palladium system

Magnesium-palladium system was found to efficiently decolourize reactive black 5, sunset yellow FCF and tartrazine dyes. There is complete loss of visible range absorption peaks and extent of colour removal exceeded 95% within 24 h of reaction. There is appearance of new peak(s) in the UV region and/or gradual and significant shift of the λmax in the UV range during 1-24 h of reaction of dyes with Mg/Pd system. LC-MS analyses following the reaction of dyes with magnesium palladium system suggest reductive cleavage of azo bonds and formation of amines as the end products. Kinetic analyses of dye decolourization indicate that the reaction follows first order kinetics. Agreement between the experimental and predicted Michaelis-Menten plots for the decolourization of reactive black 5, sunset yellow FCF and tartrazine dyes by Mg0/Pd4+ system, suggests the correctness of Michaelis-Menten model for the prediction of dye decolourization rates by Mg0/Pd4+ system. Our investigations reveal that Mg0/K2PdCl6 system is more effective in decolourizing dyes as compared to Mg0/Pd0-alumina or Mg0 alone. Results obtained from reuse experiments suggest that Pd0 pellets have the potential for recycling which will make the treatment process cost effective. Mg0/Pd4+ system was found to be efficient in decolourizing mixture of drimarene, remazol and procion dyes as well as raw effluent generated by textile dye manufacturing company.