Application of linear free energy relationships to characterizing the sorptive characteristics of organic contaminants on organoclays from water

摘要

Linear free energy relationships (LFERs) were applied to investigate the sorptive characteristics of organic contaminants (OCs) on organoclays from water. Three cetyltrimethylammonium modified montmoril-lonites (C-Mts) were selected as representative organoclays. The sorption coefficients (log K_(oc)) of OCs on the C-Mts were calculated according to the results of batch sorption experiments. Then the LFER equations for OC sorption on C-Mts from water were developed. The results of this study showed that compared with bulk water, water saturated C-Mts are more polarizable, less polar and cohesive, and have stronger H-bond acceptor capacities and weaker H-bond donor capacities. The primary driving forces for the sorption of OCs from water to C-Mts can be ascribed to the weaker cohesive characteristics of C-Mts as well as the stronger nonspecific Van der Waals interaction between OCs and C-Mts. With increasing CTMA loading amount, the interaction between OCs and C-Mts increases whereas the C-Mts become more cohesive. Consequently, the sorption capacity of C-Mts first increases with CTMA loading amount and then decreases with further increased loading amount.