Adsorption thermodynamic, kinetic and desorption studies of Pb2+ on carbon nanotubes

Adsorption thermodynamics of Pb2+ on carbon nanotubes has been studied at various temperatures of 280, 298 and 321 K and the thermodynamic parameters, such as equilibrium constant (K-0), standard free energy changes (AGO), standard enthalpy change (DeltaH(0)) and standard entropy change (DeltaS(0)), have been obtained. A pseudo- second -order rate model has been employed to describe the kinetic adsorption processes. Desorption studies reveal that Pb2+ can be easily removed from carbon nanotubes by altering the pH values of the solution using both HCl and HNO3, indicating that carbon nanotubes are a promising absorbent for wastewater treatment. (C) 2004 Elsevier Ltd. All rights reserved.