Influence of Initial pH Value on the Adsorption of Reactive Black 5 Dye on Powdered Activated Carbon: Kinetics, Mechanisms, and Thermodynamics

The aim of this work was to investigate the influence of initial pH value (pH(0)) on the isothermal adsorption of Reactive Black 5 (RB5) dye on commercial powdered activated carbon. Four initial pH values were chosen for this experiment: pH(0) = 2.00, 4.00, 8.00, and 10.00. In order to investigate the mechanism of adsorption kinetic, studies have been performed using pseudo-first-order and pseudo-second-order kinetic models as well as an intraparticle diffusion model. In addition, thermodynamic parameters of adsorption were determined for pH(0) = 4.00. Results of this research showed that the initial pH value significantly influences the adsorption of RB5 dye onto activated carbon. The highest adsorption capacities (q(e)) and efficiencies of decolouration were observed for initial pH values of pH(0) = 2.00 (q(e) = 246.0 mg g(-1)) and 10.00 (q(e) = 239.1 mg g(-1)) due to strong electrostatic interactions and attractive pi center dot center dot center dot pi interactions, respectively. It was also shown that the adsorption of RB5 dye on activated carbon at all initial pH values is kinetically controlled, assuming a pseudo-second-order model, and that intraparticle diffusion is not the only process that influences on the adsorption rate.

Automated summary

The aim of this study was to investigate the influence of initial pH value on the isothermal adsorption of Reactive Black 5 dye on powdered activated carbon. The results showed that the initial pH value significantly affected the adsorption of RB5 dye onto activated carbon, with the highest adsorption capacities and decolouration efficiencies observed at pH(0) = 2.00 and 10.00.