Performance studies on novel solar photocatalytic reactors for decolourisation of textile dyeing wastewaters

Abstract

Two ‘Water Fountain Solar Photocatalytic Reactors’ of trapezoidal and circular configurations without any ultraviolet (UV) transparent walls were developed and the practical applicability of the reactors for solar photocatalytic decolourisation of textile dyeing wastewaters was proved for the first time. The photocatalytic reactors were operated in batch mode for 3 h so as to study the influence of operating variables <i>viz., </i>liquid volume, constant liquid depth and solar ultraviolet light intensity. The studies were carried out using simulated rinse wastewaters prepared with red dye having concentration of 40 mg/L. A catalyst dosage of 1.0 g/L was adopted and the samples were collected at 15 min interval for analysis of colour. For each study on photocatalytic decolourisation, the kinetic rate equation was arrived, from which the reaction time (i.e. the Time taken for 90% decolourisation) was derived and it was used to compare the influence of operating variables. The reaction time was less than 3h for liquid volumes upto 16 L and thereafter, it increased up to 7h. The performance of the reactors was not uniform with similar liquid depths. The influence of solar UV light intensity on the performance of the reactor was found to be significant. The scale-up of the water fountain solar photoreactors is simple and also economical as expensive and fragile UV transparent walls are not necessary.