Preparation and characterisation of a novel eco-friendly Bentonite/LDH material for removal of copper ions from solution

ABSTRACT

In this study, the preparation and characterisation of a new adsorbent prepared by hetero-coagulation of Algerian bentonite and double hydroxide are reported. The nanocomposite BNa/LDH is used as an adsorbent for the removal of copper ions. The XRD and FTIR analyse show that the BNa/LDH material is formed of LDH particles enveloped by layers of bentonite. Batch experiments were carried out to study the relationship between copper removal and various parameters such as pH solution, copper concentration, contact time and temperature. The maximum amount of copper adsorbed by the BNa/LDH hybrid material is recorded at pH 4 (67 mg/g). Adsorption equilibrium is reached after 30 minutes of contact for an initial copper concentration varying between 50 and 250 mg/L. The kinetic study indicates that the limiting step of copper adsorption by the BNa/LDH material is chemical. The intraparticle diffusion models and Elovich confirm this result. The adsorption of copper by the hybrid material in the presence of anions of different nature follows the sequence: SO₄^2-> Ac⁻> Cl⁻. A comparison of the adsorption isotherms of nickel and iron with that of copper shows that the latter has an affinity for the hybrid material. The recycling of the adsorbents was carried out by calcining the adsorption products at 500°C and the results showed a progressive reduction of the adsorption capacity. In general, we could conclude that the adsorbents studied here could be successfully applied in the cleaning of the wastewaters. The characteristics of this new material encourage promising future use in wastewater treatment applications.

KEYWORDS:

• Bentonite
• copper adsorption
• hybrid material
• LDH
• nanocomposite

Acknowledgments

²This work is supported by the Algerian CNEPRU PROGRAM E01920140015 (identification and elimination of pollutant by electrochemical process). We thank Professor Claude Forano of the school of chemistry of Clermont Ferrand (France) for his considerable help.

Disclosure statement

No potential conflict of interest was reported by the author(s).