Preparation of zinc/iron layered double hydroxide intercalated by citrate anion for capturing Lead (II) from aqueous solution

In this investigation, ultrasound irradiation has been proposed as a fast, simple and green method for the synthesis of citrate (Cit) intercalated zinc iron layered double hydroxide (ZnFe/Cit-LDH) through the co-precipitation method. The co-precipitation method created high crystallinity LDH characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and Energy-dispersive X-ray spectroscopy. The synthesized ZnFe/Cit-LDH was applied for the removal of Lead (II) ions. The absorption functions in the batch experiments were studied using the expected parameters for the maximum absorption capacities (q(m)) such as pH, contact time, and the initial concentration. The obtained qm, corresponding to Langmuir as the best model for the removal of Lead (II) ions, was 94.3 mg/g at 30 min and the pH 6, based on the outside sites accessible on the sorbent surface. The uptake kinetics was also investigated and a good agreement with the experiments was obtained. The results, therefore, revealed that the adsorption kinetics and the adsorption isotherms of Lead (II) ions on ZnFe/Cit-LDH were well-fitted by the pseudo second -order kinetic model and the Langmuir isotherm model, respectively. (C) 2018 Elsevier B.V. All rights reserved.