Kinetic and adsorption mechanism of Cu(II) and Pb(II) on prepared nanoparticle layered double hydroxide intercalated with EDTA

摘要

MgFe-LDH-EDTA was obtained by the anion exchange method, with the aim of adsorpting Cu(II) and Pb(II) from the aqueous solutions by chelating process between EDTA and metal cations. The prepared LDH was characterized by XRD, TG-DTA and FTR spectroscopy. Low-Vacuum Scanning Electron Microscope (LV-SEM) revealed that the particle size of the prepared MgFe-LDH-EDTA mainly in the range 100-150 nm. The adsorption was studied at different contact time, pH and metal concentrations. The results indicate the relatively fast adsorption of the metal cations Cu(II) and Pb(II) by MgFe-LDH-EDTA reaching the equilibrium of the uptake reaction in 2 h. The shape of the adsorption isotherm suggests specific interaction and high affinity. The batch kinetics of Cu(II) adsorption onto MgFe-EDTA were carried out and thermodynamic parameters calculated. The adsorption equilibrium constant, K-c, has been calculated at different temperatures between 306 and 323 degrees K. The values of Delta H, Delta G and Delta S were 83.4 kJ/mol, 65.0 kJ/mol and 62 J/mol K, respectively. The positive Delta H value obtained for the adsorption indicates that it is endothermic and dehydration seems to be more significant than complexation in the adsorption system.