Photokinetics of the oxidation of Coomassie Brilliant Blue by Potassium dichromate in acidic medium

Discharge of colored effluents (without decoloration), originated from textile industries create acute problems in the surroundings environment.Not alone they damage marine life by reducing the concentration of dissolved oxygen in water yet also reduce the access of sun light in the beneath aquatic herbs , weeds and plants. Therefore, it is essential to remove the colored effluent from wastewater .In this study, an oxidant (potassium dichromate) was used in different media to remove the acidic triphenyl methane azo type of dye (Coomassie brilliant Blue R-250) from textile wastewater content. For this purpose, the dye has been investigated spectrophotometrically . The percent decolorization was monitored at the ?max (530nm)in aqueous medium. Removal efficiency of CBB R-250 was observed to be sensitive to operational parameters such as initial concentration of dye and oxidizing agent, pH (acidic or basic) and temperature . The interaction of dye and oxidant was also monitored under the influence of different buffers and studied their control. Effect of the above parameters were investigated and it is conclusively stated that at moderate concentration of oxidant in acidic medium, at high temperature (313K) and low pH, decolorization of CBB R-250 dye was favoured. Spectrophotometric methods were adopted for the measurement of rate constant (k) for the decolorization of CBB R-250 and it was found to be 8.0x10-3 mole L-1 sec-1.The rate law of the reaction mechanism is Rate =k [H+ ]2 [CBB][K2Cr2O7] ,where order of reaction with respect to dye was found to be first order reaction, with respect to oxidant it was first order reaction and with respect to HCl it was noticed to follow second order kinetics. Various activation parameters were (Ea)=17.068kJmol-1, (?H?)= -32.391kJmol-1, Entropy (?S?)=-288.837J.K-1 and (?G?)=-32.500kJmol-1 respectively.