One-pot hydrothermal synthesis of thrust spherical Mg-Al layered double hydroxides/MnO2 and adsorption for Pb(II) from aqueous solutions

In this study, Mg-Al layered double hydroxides/MnO2(Mg-Al LDHs/MnO2) was synthesized by one-pot hydrothermal method, and their use for removal of Pb(II) from aqueous solutions. The produced composite was characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). A series of experimental parameters including adsorbent dose, initial pH and contact time on Pb(II) uptake was evaluated. The results showed that the morphology of as-fabricated sample was thrust spherical structure. The removal efficiency of Pb(II) reached up to 96.73% when 0.05 g MgAlLDHs/MnO2 was added in 50 mL Pb(II) solutions which the concentration was 50 mg/L at the condition of the pH 4 and 25 degrees C. Adsorption kinetic data were modeled using the pseudo-first-order, pseudo-second-order and intraparticle diffusion equations and its rate constants were evaluated. The adsorption process followed the pseudo-second-order reaction kinetics, suggesting that it was presumably chemisorption. (C) 2015 Elsevier Ltd. All rights reserved.