In adsorption studies, some parameters such as kinetic and equilibrium are important in order
to design a batch adsorber. To characterize the resistance of the hydrodynamic boundary layer, the external mass transfer coefficients can be obtained from the initial adsorption data. Whereas, the internal mass transfer coefficient can be obtained from the experimental adsorption rate data after the initial period of adsorption. A review ofliterature indicated that single resistance models based on external mass transfer can be used to calculate the external mass transfer coefficient. The diffusion of solute within the pellet through the liquid in the pores is called pore diffusion. Normally, surface diffusion occurs when the solute diffuse within the pellet along the walls of the pores.
The objective of this study was to test and evaluate Bentonite clay as an adsorbent for the
adsorption of chromium and lead ions from wastewater using Saad two resistance internal diffusion model in order to calculate the time constant and equilibrium parameters required to design a batch adsorber.