Adsorption of Zn²⁺on Algerian untreated bentonite clay

Abstract

A B S T R A C TThis 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 136.2 meq/100 g. 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 5 min and equilibrium is reached in 1 h. A maximal removal capacity is obtained for a bentonite concentration of 5 g L −1 and a zinc initial concentration of 100 mg L −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 ΔG, the adsorption of Zn 2+ on SIG untreated bentonite surfaces was spontaneous and the adsorption was an endothermic process.

pH, Ionic Strength, and Ion Competition Effect on Cu(II) and Ni(II) Sorption by a Na-bentonite Used as Liner Material

“…Monometal adsorption isotherms were obtained by mixing 0.031 g of clay sample with 25 mL metal solutions containing various concentrations of the studied metals (10,25,50,80,120,150,180, and 220 mg/L for Cu(II) and 3, 5, 7, 10, 25, 50, 100, and 150 mg/L for Ni(II)). The lower concentrations of these solutions are similar to the average Cu(II) and Ni(II) concentrations determined in an Argentinean urban waste leachate [25].…”

“…Nowadays, intelligent landfill barriers are increasingly designed to prevent liquid and chemical escape from the repository site during and after the lifetime of the landfill. For this purpose, geological materials rich in smectitic clay minerals, such as bentonites, are preferred due to its widely probed performance to reduce hydraulic conductivity of granular materials [7][8][9] and to remove different types of contaminants from aqueous solutions through the sorption process [10][11][12]. The study of sorption of heavy metals is an important part of the overall investigation required for the assessment of potential liners.…”