Photocatalytic degradation of an organic dye in some aqueous buffer solutions using nano titanium dioxide. A kinetic study

Abstract

Photocatalytic degradation of an organic dye, emerald green, on nano titanium dioxide (anatase 99.5%) at basic buffer pH of 7, 8 and 9 has been investigated. The effects of various operating parameters such as initial concentration of dye, catalyst dosage, bufferic pH and irradiation time on photocatalytic degradation have been studied in a photoreactor cell containing high pressure mercury lamp to obtain the optimum conditions. COD removal was found to be 65-71% confirming considerable mineralization. The photodegradation of the dye obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model at all used buffer pH. The observed rate constants (k obs ) of photocatalytic degradation were 3.3 10 -2 min -1 , 7.09 10 -2 min -1 and 1.32 10 -1 min -1 at buffer pH of 7-9 respectively. Furthermore, the Langmuir-Hinshelwood rate constants, k r and adsorption constants, K A are reported for current process at various buffer pH.