Removal of Cd(II), Cu(II), and Pb(II) by adsorption onto natural clay: a kinetic and thermodynamic study

Brahim Abbou; Imane Lebkiri; Hanae Ouaddari; Lamya Kadiri; Abdelkarim Ouass; Amar Habsaoui; Ahmed Lebkiri; El Housseine Rifi

doi:10.3906/kim-2004-82

Removal of Cd(II), Cu(II), and Pb(II) by adsorption onto natural clay: a kinetic and thermodynamic study

Turk J Chem. 2021 Apr 28;45(2):362-376. doi: 10.3906/kim-2004-82. eCollection 2021.

Authors

Brahim Abbou¹, Imane Lebkiri¹, Hanae Ouaddari², Lamya Kadiri¹, Abdelkarim Ouass¹, Amar Habsaoui¹, Ahmed Lebkiri¹, El Housseine Rifi¹

Affiliations

¹ Department of Chemistry, Faculty of Science, Ibn Tofail University, Kenitra Morocco2.
² Department of Chemistry, Faculty of Science, Hassan II University, Mohammedia Morocco.

Abstract

In this work, we study the elimination of three bivalent metal ions (Cd²⁺, Cu²⁺, and Pb²⁺) by adsorption onto natural illitic clay (AM) collected from Marrakech region in Morocco. The characterization of the adsorbent was carried out by X-ray fluorescence, Fourier transform infrared spectroscopy and X-ray diffraction. The influence of physicochemical parameters on the clay adsorption capacity for ions Cd²⁺, Cu²⁺, and Pb²⁺, namely the adsorbent dose, the contact time, the initial pH imposed on the aqueous solution, the initial concentration of the metal solution and the temperature, was studied. The adsorption process is evaluated by different kinetic models such as the pseudo-first-order, pseudo-second-order, and Elovich. The adsorption mechanism was determined by the use of adsorption isotherms such as Langmuir, Freundlich, and Temkin models. Experiments have shown that heavy metals adsorption kinetics onto clay follows the same order, the pseudo-second order. The isotherms of adsorption of metal cations by AM clay are satisfactorily described by the Langmuir model and the maximum adsorption capacities obtained from the natural clay, using the Langmuir isotherm model equation, are 5.25, 13.41, and 15.90 mg/g, respectively for Cd(II), Cu(II), and Pb(II) ions. Adsorption of heavy metals on clay is a spontaneous and endothermic process characterized by a disorder of the medium. The values of ΔH are greater than 40 kJ/mol, which means that the interactions between clay and heavy metals are chemical in nature.

Keywords: Clay; FTIR; adsorption; heavy metals; isotherm; thermodynamic.