Adsorptive removal of Basic Violet 2 from aqueous solutions using wal nut shells as low-cost adsorbents

In this study, wal nut shell (WNS) has been used as a low-cost adsorbent for the removal of a cationic dye Basic Violet 2 (BV2) from aqueous solution under different experimental conditions. Batch adsorption studies were carried out to evaluate the effect of various parameters such as pH, initial dyeconcentration, adsorbent dosage, contact time, particle size of adsorbent and temperature. The results showed that the amount of adsorbed dye increasedwith increase in initial dye concentration, contact time, adsorbent dosage and temperature. Adsorption was shown to be strongly dependent of pH. Theisotherms of adsorption data were analyzed by Langmuir, Freundlich, Temkin and Redlich- Peterson models. The Langmuir isotherm provided the best fit for the experimental data of the equilibrium adsorption of BV2 onto WNS. The kinetic experimental data were fitted to pseudo- first order,pseudo- second order and intra- particle diffusion models. The kinetic analysis exhibited that the pseudo- second order model had the best fit to theexperimental data. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also calculated. The thermodynamicevaluation revealed that the adsorption phenomenon under the selected conditions was a spontaneous physical process. Experimental results confirmed that BV2 can be successfully removed from aqueous solutions by a very efficient and low- cost adsorbent