Adsorption of Zn (II) on Acacia Tortilis Leaves Treated with Sulfuric Acid: Kinetic Studies

Abstract

Abstract--In the present work, the potential use of Acacia tortilis leaves to remove Zn(II) from water media was evaluated. In case to activate the surface of Acacia tortilis leaves, some acids such as sulfuric, phosphoric and hydrochloric of 0.1 meq/ml were tried. High adsorption capacity was obtained when sulfuric acid was used. Kinetic data was measured in batch condition. The effect of some parameters such as: initial pH, adsorbent dosage and contact time on the adsorption of Zn(II) has been studied. Zn(II) adsorption was initial pH, adsorbent dosage and time contact dependent. It has been found that the adsorption capacity of Zn(II) on Acacia tortilis leaves increased as initial pH increased and rich equilibrium at pH 4. On the other hand, the adsorption capacity of Zn(II) decreased as adsorbent dosage increased. The maximum adsorption capacity of Zn(II) was found to occur after two hours. Three kinetic models including fist order, pseudo second order and intra particle diffusion were selected to follow the adsorption process. The process follows a pseudo second order. The following parameters used in this research are constant: contact temperature, 25 o C±1; stirring speed, 400 rpm ; Zn(II) concentration, 400 mg/l and adsorbent size, less than 90 µm.