The compound-specific mechanisms for the sorption of organic contaminants onto cetyltrimethylammo nium-saturated bentonite (i.e., CTMA-Bentonite) in water were evaluated by H-1 NMR study and Linear Solvation Energy Relationship (LSER) approach. In H-1 NMR study, comparing with pure CTMAB, the up-field shifts of hydrogen peaks for -CH2N+ and CH3N+ of CTMA(+) in CTMAB-aromatics (1-naphtylamine, aniline and phenol) mixtures are much greater than that in CTMAB-aliphatics (cyclohexanone and cyclohexanol) mixtures. Meanwhile, the peak position of hydrogen on amino- and hydroxyl-groups of aromatic compounds also changes greatly. H-1 NMR data demonstrated the strong molecular interaction between the positive ammonium group of CTMA(+) and the delocalized it-systems of aromatic solutes, whereas the interactions of CTMA(+) with aliphatic compounds having electron-donating groups (such as cyclohexanol and cyclohexanone) or aromatic ring substituted by electron-withdrawing groups (i.e., nitrobenzene) or nonpolar aromatic compounds with single phenyl ring (i.e., toluene) are weak. The derived LSER equation was obtained by a multiple regression of the solid-water sorption coefficients (K-d) of 16 probe solutes upon their solvation parameters, and demonstrates aromatics sorption onto CTMA-Bentonite is concurrently governed by the pi-/n-electron pair donor-accepter interaction and the cavity/dispersion interaction, while the predominant mechanism for aliphatic compounds is the cavity/dispersion interaction, consisting with the H-1 NMR results. (C) 2015 Elsevier Inc. All rights reserved.