UV photolytic decoloration of aqueous solutions of some synthetic dyes

The presence of colour in the waste water is highly undesirable since it may interfere in the biological activity of marine life as well as the aesthetic appeal. The removal of colour in ecofriendly manner is the need of hour in view of the stringent rules and regulations all over the globe as far as the impact of these on the environment is concerned. Many studies has strongly reveled the potential of Advanced Oxidation Processes in achieving the feat in clean and ecofriendly manner. UV photolysis, one of the A.O.P.s also has been employed to achieve efficient decoloration. Though, UV photolysis alone has certain limitations owing to its ability to degrade complex organic substances, but when paired with H2O2 or Fenton’s Reagent, has reported to produce excellent results. The addition of these substances boosts the generation of highly oxidizing –OH ions which are responsible for the destruction of colour bearing chromospheres leading to decoloration. In present study, the UV photolytic decoloration of aqueous solutions of some synthetic dyes namely Methylene Blue (MB), Malachite Green (MG) and Indigo Carmine (IC) which are used commercially on large scale was carried out using low pressure Hg lamp (12W) in a specially designed set up. Further, the synergistic effect of H2O2 as an additive on the fate of decoloration was investigated. The changes in parameters of solutions such as conductance, pH etc. were also recorded.