Adsorption of reactive dye on activated carbon: kinetic study and influence of initial dye concentration

Abstract

Although many of the dyes used in dyeing process are not toxic, dyed effluents have harmful and negative aesthetic and biological effect on water systems, and therefore dyes should be removed from wastewaters. This paper deals with isothermal adsorption of Reactive Black 5 dye on commercial activated carbon. Batch adsorption study was carried out in different periods, from 30 minutes to 16 hours, when equilibrium was reached. Results show exponential lowering of dye concentration after adsorption, from 500 mg dm-3 to 118 mg dm-3 at equilibrium. In order to investigate the mechanism of adsorption kinetic studies have been performed, and pseudo-second order kinetic model better describes adsorption process of this system. The aim of this work was also to compare influence of initial dye concentration on the adsorption process; percentage of adsorbed dye at equilibrium for initial dye concen-tration c0 = 300 mg dm-3 is for 18 % bigger than that of c0 = 500 mg dm-3.