The efficacy of un-calcined sodium exchanged (Na-MMT) and acid modified montmorillonite (A-MMT) has been investigated for adsorptive removal of Ni2+ from aqueous solution. Physico-chemical parameters such as pH, initial Ni2+ concentration, and equilibrium contact time were studied in a series of batch adsorption experiments. The equilibrium time of contact for both adsorbents was about 230 min. The Redlich-Peterson model best described the equilibrium sorption of Ni2+ onto Na-MMT and the Dubinin-Radushkevich model was the best model in predicting the equilibrium sorption of Ni2+ onto A-MMT. The kinetics of Ni2+ uptake by Na-MMT and A-MMT followed the pseudo second-order chemisorption mechanism. Sorptions of Ni2+ onto Na-MMT and A-MMT were spontaneous and endothermic. Regeneration was tried for several cycles with a view to recover the adsorbed Ni2+ and also to restore Na-MMT and A-MMT to their original states. The un-calcined Na-MMT and A-MMT have adsorptive potentials for removal of Ni2+ from aqueous bodies.
Bibliographical noteFunding Information:
The authors appreciate the supports of the Schlumberger Stiching Fund, the ERC program of the National Research Foundation (NRF), Korea and the Korea Institute of Geoscience and Mineral Resources (KIGAM) towards this project.