Sorption of lead ion by layered double hydroxide intercalated with diethylenetriaminepentaacetic acid

Mg2Al layered double hydroxide (Mg2Al LDH) samples intercalated with diethylenetriaminepentaacetic acid (DTPA) (Mg2Al–DTPA LDH in short) were prepared by co-precipitation and well characterized by XRD, SEM, TEM, IR and XPS. The sorption behaviors and mechanisms of Pb2+ on the samples were studied in detail while Mg2Al–Cl LDH as a reference. The maximum sorption amounts were about 170 and 40 mg/g for Mg2Al–DTPA LDH and Mg2Al–Cl LDH, respectively. Langmuir isotherm was proved to describe the sorption data better and pseudo-second order kinetic model could fit the sorption kinetic processes better for both LDHs samples. The mechanisms of Pb2+ sorption on Mg2Al–DTPA LDH can be explained by Pb–DTPA chelating while that for Mg2Al–Cl LDH is primary surface-induced precipitation. The Mg2Al–DTPA LDH could provide a potential remedy for heavy metal contamination in soils and water.