Kinetic and Equilibrium Studies of Cd (II) Adsorption from Aqueous Solutions Using Natural Clay

Abstract

This study investigates the kinetics and equilibrium of cadmium Cd (II) ion removal from aqueous solutions using natural clay collected from Al-Khums, Libya, as a low-cost adsorbent. Batch adsorption experiments were conducted to evaluate the effects of contact time, solution pH, adsorbent dosage, initial Cd(II) concentration, and temperature on adsorption performance. E. The optimum adsorption conditions were pH 6.0, an adsorbent dosage of 3 g, and an equilibrium time of 60 min. Under these conditions, the maximum Cd (II) removal efficiency reached 94.3%, and the adsorption efficiency increased with increasing temperature, indicating a favorable effect of temperature on the adsorption process. The Langmuir isotherm provided the best fit to the equilibrium data, suggesting predominantly monolayer adsorption, while the pseudo-first-order kinetic model adequately described the adsorption behavior. These findings demonstrate that the natural clay from Al-Khums is an effective, inexpensive, and environmentally friendly adsorbent for the removal of Cd (II) ions from contaminated aqueous solutions.