Equilibrium modeling of removal of cadmium ions by olive stones

This article addresses the equilibrium for cadmium biosorption using olive stones as a sorbent material over a range of temperatures between 25 and 80 degrees C Three models frequently used in the literature-Langmuir, Freundlich, and Redlich-Peterson-were examined to describe these equilibrium data. The experimental results fit Langmuir's model for the majority of temperatures tested. The maximal biosorption capacity, q(m), increases with temperature, rising from 4.52 mg/g at 25 degrees C to 9.72 mg/g at 80 degrees C Also, the affinity of olive stones for cadmium, represented by parameter b in Langmuir's model, increases when the temperature is raised from 25 to 80 degrees C. Finally, the shape of Langmuir's model, represented by the dimensionless parameter K-R, shows that cadmium biosorption with olive stones works well at the temperatures and initial cadmium concentrations tested in this study.