Spectroscopic and Mineralogical Characterization of Bentonite Clay (Ghardaia, Algeria) for Heavy Metals Removal in Aqueous Solutions

A natural clay material, from El Menia (Ghardaia, Algeria), was used as a potential raw material for wastewater treatment. A clay sample was used in its raw and activated form. Physico-chemical properties of both samples were assessed by chemical analyses, grain size distribution, X-ray diffraction, N-2 adsorption-desorption, scanning electron microscopy, thermogravimetry, X-ray fluorescence and Fourier transform infrared spectroscopy techniques. To our knowledge, this is the first study that investigates the removal heavy metal ions such as Pb2+, Zn2+, Cu2+ and Ni2+ ions from aqueous solution using adsorption method onto natural clay from El-Menia (Ghardaia) under different conditions. Physico-chemical parameters such as the effects of adsorbent dose, pH, contact time and initial concentration were studied in a series of batch adsorption experiments at 25 degrees C. The obtained results revealed very high removal percentages 98%, 81%, 93% and 84% for Pb2+, Zn2+, Cu2+ and Ni2+ ions, respectively. Adsorption kinetics fitted well the pseudo-second-order model. Langmuir, Freundlich and Temkin adsorption isotherms were used to evaluate their potential fit to the experimental data. Thermodynamic parameters (Delta H degrees, Delta S degrees, and Delta G degrees) indicated spontaneous and exothermic adsorption processes.