Photocatalytic decolourisation of industrial wastewater from a soft drink compan

Abstract

The photocatalytic decolourisation of industrial wastewater from a soft drink company was investigated. Four
catalysts namely titanium dioxide (TiO2), zinc oxide (ZnO), periwinkle shell ash (PSA) and snail shell ash (SSA)
were evaluated for their potential use as photocatalysts for decolourisation of wastewater. Two sets of preliminary
experiments were carried out, the first without light and the second in the presence of sunlight to determine the best
catalyst for the study. Results of preliminary studies showed that PSA was best suited for the decolourisation of the
wastewater samples hence it was chosen for further studies. The percent decolourisation was monitored
spectrophotometrically by the measurement of absorbance at a wavelength of 201nm. The effect of catalyst dosage
and oxidant (H2O2) loading on the degradation process was investigated. The percent decolourisation increased with
increase in PSA dosage with a dosage of 12 g/L resulting in the maximum percent decolourisation of 62%. Addition
of oxidant enhanced the photodegradation process with almost 100% decolourisation achieved. The degradation
process conformed to a pseudo first order reaction and this was appropriately described by the Langmuir-
Hinshelwood kinetic model.