The adsorption of Pb(II) on Mg2Al layered double hydroxide

The adsorption behavior of Pb(II) by Mg2Al layered double hydroxide (Mg2Al LDH) was studied as a function of contact time, pH, ionic strength, foreign ions, humic substances and temperature under ambient conditions. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The adsorption of Pb(II) on Mg2Al LDH was strongly dependent on pH and ionic strength. The presence of HSs enhanced the adsorption of Pb(II) on Mg2Al LDH at low pH, whereas reduced Pb(II) adsorption at high pH. The Langmuir model fitted the adsorption isotherms of Pb(II) better than the Freundlich model at three different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent adsorption isotherms indicated that the adsorption process of Pb(II) on Mg2Al LDH was endothermic and spontaneous. The results show that Mg2Al LDH is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.

► Pb(II) adsorption on Mg2Al LDH was dependent on pH and ionic strength.
► HSs enhanced Pb(II) adsorption on Mg2Al LDH at low pH, whereas reduced Pb(II) adsorption at high pH.
► The Langmuir model fitted the adsorption isotherms of Pb(II) well.
► Pb(II) adsorption on Mg2Al LDH was endothermic and spontaneous.