CONCLUSION
This study for the adsorption of lead and chromium ions on Bentonite clay showed that Saad
isotherm model agreed most favorably with the experimental data. Calculations of the internal
diffusion time constants to characterize the slow rate of adsorption indicated that most of the
adsorption occurred during the initial period. This phenomena of adsorption occurrence at the
initial period suggested that internal diffusion is the major rate-controlling step for quantifying the rate of lead and chromium ions removal from wastewater.