Photocatalytic degradation of reactive dyes and simulated dyebath wastewater.

ABSTRACT

The study related to photocatalytic degradation of three reactive dyes, namely, Reactive Red 141 (RR141), Reactive Orange 16 (RO16) and Reactive Violet 13 (RV13) was carried out. Further, two simulated textile dyebath wastewaters were prepared and examined for photocatalytic degradation. Three dyes were subjected to photodegradation in a batch annular immersion well photoreactor equipped with a 400W Medium Pressure Mercury Lamp (MPML). The UV illuminated TiO2 containing aqueous suspensions found to remove colour as well as chemical oxygen demand (COD). The photocatalytic activity was monitored by measuring the rates of decolorization and COD removal as a function of concentration of the dye and treatment time. The photodegradation efficiency of these three reactive dyes was found in the order of RR141 > RO16 > RV13. The first order rate constant (k(app)) for decolorization was 3-9 times higher than the k(app) for COD removal. The rate constants for degradation of simulated wastewater were also of the similar order of magnitude. These results suggest that TiO2/UV photocatalysis may be envisaged as a method for treatment of diluted coloured wastewaters not only for decolourization, but also for polishing of the COD parameter.