Author(s)

Mahfoud Barkat, Salah Chegrouche, Abdelhamid Mellah, Belgacem Bensmain, Djamel Nibou, Makhlouf Boufatit

Centre de Recherche Nucléaire de Draria, Commissariat à l’Energie Atomique, Algiers, Algeria.
Faculty of Chemistry, University of Sciences and Technology Houari-Boumediene, USTHB, Algiers, Algeria.
Faculty of Mechanical and Process Engineering, University of Sciences and Technology Houari-Boumediene, USTHB, Algiers, Algeria.

The aim of this study is to report batch adsorption results of Cd (II) and Cr (VI) onto Algerian bentonite. The equilibrium adsorption process was achieved at about 120 min contact time. The kinetic and isotherms aspects of Cr (VI) and Cd (II) adsorption were investigated by varying operation parameters such as pH (0.5 - 6), initial Cd (II) and Cr (VI) concentrations (50 - 200 mg/l) and temperature (293.15 K - 343.15 K). The optimum conditions obtained were: pH = 6.0 and 4.0 for Cd (II) and Cr (VI) respectively, initial concentrations of Cd (II) and Cr (VI) = 50 mg/L and T = 293.15 K. The kinetic of the adsorption process was studied by application of the most important kinetic models namely the pseudo-first order, the pseudo-second order and Elovich equations. The results showed that the pseudo-second order model fitted well the adsorption data of Cr (VI) whereas, and the Cd (II) adsorption data fitted best the Elovich equation. The equilibrium data fitted best the Langmuir isotherm, and the maximum adsorption capacity was determined through this model and was found to be 13.17 and 12.61 mg/g for Cd (II) and Cr (VI) respectively. The temperature had a reverse effect on the Cd (II) and Cr (VI) adsorption; our results showed that the removal efficiency increased to82.4% and 55.70% for Cd (II) and Cr (VI)when the temperature decreasedto 293.15 K.The negative figures of the Gibbs free energy ΔG°_ads values range from －15.23 kJ/mol to －14.37 kJ/mol for Cd (II) and from －9.70 kJ/mol to －9.64 kJ/mol for Cr(VI) at 293.15 K to 343.15 K showed that the adsorption process is spontaneous and favourable. These results confirmed the ability of the low-cost Algerian natural bentonite to efficiently and competitively adsorb the two toxic elements investigated: cadmium (II) and chromium (VI).

Adsorption, Cadmium, Chromium, Langmuir, Bentonite

Barkat, M. , Chegrouche, S. , Mellah, A. , Bensmain, B. , Nibou, D. and Boufatit, M. (2014) Application of Algerian Bentonite in the Removal of Cadmium (II) and Chromium (VI) from Aqueous Solutions. Journal of Surface Engineered Materials and Advanced Technology, 4, 210-226. doi: 10.4236/jsemat.2014.44024.