HEXAVALENT CHROMIUM ADSORPTION CAPABILITY ONTO CARBON BLACK: KINETIC AND THERMODYNAMIC ASPECTS

Abstract

The adsorption rate and dynamic behaviour of the system are important factors in the process design and operation control. The aim of this study was to find a suitable kinetic model for the hexavalent chromium removal in a batch reactor. The experimental data were analyzed using four adsorption kinetic models – the pseudo first- and second-order equations, the Elovich equation and intraparticle diffusion equation – so as to determine the best fit equation for the adsorption of Cr(VI) onto the carbon black. The rate constants and related correlation coefficients for each kinetic model were calculated and discussed. Also, the predicted qe, cal values from the kinetic equations were compared with the experimental data. Results showed that the pseudo second- order equation provides the best correlation for the adsorption process, whereas the Elovich equation also good fits with the experimental data. The values of the thermodynamics parameters, including the energy of activation, suggest that physisorption is dominant for the adsorption of Cr(VI) onto the carbon black.