A Novel Acrylic Intercalated Hydrotalcite for the Removal of Heavy Metal Ions from Aqueous Solution: Isotherm, Kinetics, Thermodynamics and Mechanism

Abstract

In this paper, due to the anion exchange between the hydrotalcite layers, the functional nano-acrylic pillared hydrotalcite(AA-LDH) were prepared via back-mixing precipitation method with acrylic acid as the intercalation modifier. AA-LDH was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption performance of AA-LDH for Pb(II), Cu(II), Zn(II) and Cd(II) was investigated. The maximum adsorption capacities of the AA-LDH were up to 4.35 mmol g-1 for Pb(II), 3.67 mmol g-1 for Cu(II), 1.75 mmol g-1 for Zn(II) and 1.23 mmol g-1 for Cd(II) at pH 5.0. The effects of pH on the adsorption suggested that the adsorption of metal ions was governed mainly by the chelation interaction. The adsorption isotherms of the three metal ions were best described by the Langmuir model, and their adsorption kinetics followed the pseudo second-order kinetic equation. The adsorption equilibrium was reached for the four ions within 3h. The adsorption of the three concerned metal ions was hardly affected by common coexisting ions such as Na(I), K(I), Ca(II) and Mg(II), whereas they were slightly decreased when Fe(II) coexisted in the solution, which illustrates the selective adsorption of Pb(II), Cu(II), Zn(II) and Cd(II) from wastewater. The AA-LDH has a good desorption rate and reusability. These findings suggest that the AA-LDH could be potentially applied to the efficient removal of heavy metal ions from waste water.