Monte Carlo adsorption affinity studio of modified nano-montmorillonite for the removal of chromate ions

Abstract

A biosurfactant, n-hexadecyl-1-beta-D-maltopyranoside (HMP), and a broadly used cationic surfactant, hexadecyltrimethylammonium (HDTMA), were used as montmorillonite clay modifiers for an in silico study to explore the most stable adsorption sites for the trapping of chromate (CrO4−2) contaminant. Monte Carlo searches have been used to find low energy configurations of substrate with the adsorbate to identify the possible adsorption sites. There was found that the CrO4 proximity of the polar head of the HDTMA surfactant and at less than 3 A from the Ca2+ ions. In the case of HMP the CrO4−2 ion was mostly located far away from its polar head but located in all cases at less than 3 A from the Ca2+ ions. In summary, we have found that configurations that showed best adsorption results corresponded to the systems where the contaminant was closer to the polar head of the HDTMA surfactant.