Brazilian kaolinite clay was used to study urea intercalation (K UR) and delamination (Kur/DL) processes. The intercalated sample was delaminated by ultrasonic treatment in acidic solution. The basal distance changed from 0.72 to 1.08 nm with increasing surface area from 20.3 to 90.5 m² g-1 for K UR and K UR/DL. Suspended pristine, intercalated and delaminated clays at pH 5.0 adsorbed copper and lead cations at the solid/liquid interface. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models were employed in linear and nonlinear regression processes, to give b and K L values for all kaolinites. The highest adsorption capacity of 12.8 mmol g-1 was obtained with delaminated kaolinite. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k2 in the 5.0 to 11.0 and the 4.9 to 13.0 mmol-1 min-1 ranges for copper and lead cations, respectively.
kaolinite; adsorption; heavy metals; kinetics; delamination
