Preparation and characterization of calcined Ni/Mo hydrotalcite for the effective removal of lead from wastewater

ABSTRACT

In this investigation, calcined Ni/Mo hydrotalcite was prepared via co-precipitation method and used as a sorbent for efficient removal of lead from aqueous solutions. The Pb²⁺ removal efficiency reached 99% at pH 6 and a sorbent dose of 2 g/L. The equilibrium data were satisfactorily fitted by the Langmuir and Hill models with a maximum capacity of 196.87 mg/g, indicating the monolayer sorption for lead over calcined Ni/Mo hydrotalcite. The Pb²⁺ sorption kinetic follows a pseudo-second-order reaction due to high correlation coefficients (R²> 0.99), while the Boyd’s plots confirm the external mass transfer as the rate-limiting step in the Pb²⁺ sorption. The temperature effect indicated a spontaneous and exothermic Pb²⁺ uptake. Mechanisms involved in the removal process include surface precipitation, diffusion into the solid pores and isomorphic substitution with Ni²⁺ of the sheets. The results showed excellent selectivity for Pb²⁺ removal from multi-divalent cation solutions and good reusability of the sorbent for up to 10 consecutive sorption–regeneration cycles without significant loss of the removal efficiency. As an application, the treatment of wastewater containing Pb²⁺, generated from the battery industry has been undertaken. The Pb²⁺ concentration was reduced from 5.7 to 0.6 mg/L, corresponding to an abatement of 89.5%. Therefore, the sorption using calcined Ni/Mo hydrotalcite is an efficient and suitable method for the elimination of Pb²⁺.

GRAPHICAL ABSTRACT

KEYWORDS:

• Kinetic
• layered double hydroxides
• lead
• sorption
• wastewater

Acknowledgements

Author’s contributions: Khitous Mohamed and Trari Mohamed conducted the experiments, interpreted the data and analysis and drafted the manuscript. All authors reviewed and approved the manuscript.

Disclosure statement

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

Ethics approval and consent to participate

This article does not contain any studies with human participants or animals performed by any of the authors. All authors read, approved the final manuscript, and agreed for this submission.