Abstract:

Well crystalled MgAl-layered double hydroxide(MgAl-LDH) and EDTA-LDH nanohybrids were synthesized via a co-precipitation method and characterized. The ligand EDTA is probably accommodated in vertical position in the interlayer space of LDH. The sorption behavior of MgAl-LDH and EDTA-LDH nanohybrids for lead ions was also investigated as a function of concentration, pH and time. It is found that both of them show good sorption ability for Pb2+. The sorption rate and the equilibrium sorption amount of Pb2+ are higher on EDTA-LDH nanohybrids than on MgAl-LDH under identical conditions, which indicate the intercalation of EDTA exhibits synergy. The sorption can be described by the pseudo-second order kinetics. The sorption occurrs in two steps, an adsorption process followed by surface precipitation. The adsorption isotherms are well fitted to Freundlich isotherm. Within the experimental concentration range, the variation of adsorbed amount is not obvious with the variation of pH because of the compound having a property of buffering pH(buffering pH effect).

Key words: layered double hydroxide,EDTA,lead,adsorption