Biosorption equilibrium and kinetics of copper (II) from aqueous solution using dead leaves of plane tree

The dead leaves of plane tree were investigated as a low-cost biosorbent for the removal of Cu²⁺ from aqueous solution in a batch system. Different environmental factors such as initial Cu²⁺ concentration, contact time, biosorbent dose, temperature and pH were studied. The sorption was found to be maximum in natural medium and increases with increase in initial concentration. Langmuir, Freundlich and Temkin isotherm model were applied to describe the biosorption of the metal ions onto biosorbent. Langmuir and Freundlich model fitted the equilibrium data better than the Temkin isotherm. Modeling of kinetic results shows that sorption process is best described by of the pseudo-second order model. intra-particle diffusion model indicated the adsorption of Cu²⁺ onto dead leaves is controlled by both external mass transfer and intra-particle diffusion.