Adsorption of Zn2+ on Algerian untreated bentonite clay

摘要

This work has the purpose of evaluating the removal of zinc from aqueous solutions using Algerian untreated bentonite clay as an adsorbent. The choice of using natural untreated clay is justified by the fact that it is both a low cost and friendly environmental adsorbent material. This local bentonite is a montmorillonite clay type with a relatively high cationic exchange capacity of 136.2meq/100g. Calcium is the main exchangeable cation. A granulometric analysis shows that 49.1% of the clay particles are submicronic. The zinc adsorption capacity of bentonite was studied in batch mode. A kinetic study shows a fast removal capacity and a highly influenced bentonite adsorption capacity by the operational parameters such as contact time, mass of adsorbent, metal concentration, pH, and temperature. Fifty percent of the Zinc was removed during the first 5min and equilibrium is reached in 1h. A maximal removal capacity is obtained for a bentonite concentration of 5gL(-1) and a zinc initial concentration of 100mgL(-1). A pseudo-second-order kinetic model could be fitted to the experimental data. The equilibrium data could be fitted with a Langmuir isotherm equation. Depending on the negative value of G, the adsorption of Zn2+ on SIG untreated bentonite surfaces was spontaneous and the adsorption was an endothermic process.