In this study, the adsorption, bridging, and intercalation effects of a cationic surfactant, benzyldimethyltetradecyl ammonium chloride (BDTDACI), on bentonite clay suspensions was investigated. The adsorption, rheological behaviors, and colloidal properties of the clay dispersions were determined as a function surfactant concentration. Adsorption isotherms were obtained using the batch-equilibrium technique. The theological behavior of the clay suspensions was obtained by shear stress shear rate measurements within 0-350 s(-1) shear rates. The structure of the composite particles was analyzed by using X-ray diffraction analysis and it was found that the expansions of basal d-spacings are less than 16.80 angstrom, suggesting a monolayer structure. (c) 2006 Elsevier Inc. All rights reserved.