The sorption of phenol, m-nitrophenol (m-NP), and o-cresol from water onto montmorillonite modified with cetyltrimethylammonium bromide (CTAB) in a column was studied. The sorption isotherms were fitted by the Langmuir equation. Column experiments were performed at 25 degreesC to determine the breakthrough curves at different flow rates, feed sorbate concentrations, and bed lengths. It was shown that the proposed constant-pattern wave approach with the Langmuir model could well describe the breakthrough curves. The time required when the effluent concentration reached half of the feed concentration (t(1/2)) decreased with increasing feed flow rate, but the mass transfer coefficient (K(L)a) increased. In addition, an increase in feed sorbate concentration led to a decrease of both values of t(1/2) and K(L)a. The effect of axial dispersion on breakthrough dynamics in these sorption systems was finally discussed. (C) 2003 Elsevier Inc. All rights reserved.