Sorption of uranium from aqueous solutions using palm-shell-based adsorbents: a kinetic and equilibrium study

In this study adsorbents based on palm shell powder as well as modified and activated palm shell powder were studied to analyze their behavior in sorbing U6+ by both batch and fixed column modes. Seven different two-parameter isotherm models were applied to the experimental data to predict the sorption isotherms. The Delta G(0) values from Langmuir and thermodynamic calculations indicate physisorption as the major mechanism for adsorption of uranium. Usefulness of various kinetic models like pseudo first order, pseudo second order, intraparticle diffusion, Bangham, Elovich and Liquid film diffusion were tested. The adsorption capacities were found to be greater than 200 mg/g for all the adsorbents under study. The column data were fitted by Thomas, Yoon and Nelson as well as Wolborska models. The Thomas and Yoon and Nelson models were best to fit the breakthrough curves under the experimental conditions studied. (C) 2013 Elsevier Ltd. All rights reserved.