EFFECT OF SURFACE CHARGE ON PHOTOCATALYTIC REDUCTION OF CATIONIC DYES BY ZINC OXIDE POWDER: A COMPARATIVE STUDY

Ritu Vyas*, Deepak Swarnkar and Suresh C. Ameta

ABSTRACT

The field of photocatalysis has opened new avenues of research in chemistry, as many chemical reactions can now be driven photocatalytically, which was not possible by ordinary chemical or photochemical methods. The photoreduction of cationic dyes (Brilliant green and Crystal violet) in presence of ZnO as photocatalyst has been carried out. The rate of this photochemical reaction was observed spectrophotochemically. The effect of different parameters like pH, concentration of dyes, amount of semiconductor and light intensity on the reaction rate was observed .The effect of charge of different cations, anions and ligands on the reaction rate was also studied by taking cations like Na+, Ba2+, Al3+, anions like Cl-, SO42-, PO43- and ligands like EDTA, NTA. Further behavior of photocatalytic bleaching was studied by varying the concentration of cation (Ba2+), anion (PO43-) and ligand (EDTA). A tentative mechanism for the photocatalytic degradation of dyes has also been observed.

Keywords: Photodegradation, Photocatalytic bleaching, Zinc oxide, Cationic dyes.