Revista de Ciencias Químicas

Langmuir-Hinshelwood Kinetic Expression for the Photocatalytic Degradation of Metanil Yellow Aqueous Solutions by ZnO Catalyst

Abstract

S Khezrianjoo, HD Revanasiddappa

The kinetics studies of the adsorption and degradation phenomena involved in the photocatalytic degradation of Metanil Yellow (MY) were investigated using a batch reactor and UV light irradiation. Experiments were performed in a suspended ZnO system at natural pH of 6.93 and catalyst concentration of 1 g L-1. The initial concentration of MY varied between 10- 50 mg L-1. The kinetic analysis of the photodecomposition of MY showed that the disappearance followed satisfactorily the pseudo first-order according to Langmuir—Hinshelwood model. From the results, the adsorption was found to be an essential factor in the photodegradability of the dye. The linear transform of the Langmuir isotherm curve was further used to determine the characteristic parameters which were: maximum absorbable dye quantity Qmax = 6.802 mg g_1 and adsorption equilibrium constant Kads = 0.168 L mg_1. The adsorption constant calculated from the linear form of this model, KLH = 0.155 L mg_1 was found reasonably similar to Kads deduced from isotherm adsorption.