Equilibrium, kinetics and thermodynamic parameters for adsorptive removal of dye Basic Blue 9 by ground nut shells and Eichhornia

Abstract

Adsorption of dye Basic Blue 9 (BB9) was studied using ground nut shells charcoal (GNC), and Eichhornia charcoal (EC) as adsorbents. The characterization was done with FTIR spectroscopy, scanning electron microscopy and X-ray diffraction. Batch adsorption studies have been investigated by measuring the effect of pH, adsorbent dose, adsorbate concentration, contact time, temperature, and ionic strength. Adsorption of the dye increased with increase in contact time, temperature, amount of adsorbent and initial concentration. The kinetic experimental data were fitted to pseudo-first order, pseudo-second order, intra-particle diffusion, Elovich model and Bangham’s model and corresponding constants were calculated and discussed. Pseudo-second order kinetics was found to describe the adsorption of dye BB9 on both the adsorbents and rate is mainly controlled by intra particle diffusion. A study of five isotherm models; Langmuir, Freundlich, Temkin, Dubinin and Radushkevich and generalized isotherms have been made and important thermodynamic parameters have been obtained. The adsorption of BB9 onto GNC and EC was spontaneous and endothermic as concluded from thermodynamic assays. Experimental results confirmed that dye BB9 can be successfully removed from the aqueous solutions economically and efficiently.