The layer-by-layer electrostatic assembly process and chemical cross-linking technology were developed for Cu(Ⅱ) ion-imprinted composite membranes. Poly(acrylic acid) and polyethylenimine-copper(Ⅱ) ion complexes were assembled alternately on the surface of microporous polypropylene membrane (MPPM) by electrostatic action. Then the assembled layers were cross-linked by epichlorohydrin. The Cu(Ⅱ)-ion imprinted composite membranes obtained after the removal of Cu(Ⅱ) ions with acetic acid

characterized by Fourier transform infrared spectroscopy

X-ray photoelectron spectroscopy and environmental scanning electron microscopy

show satisfactory hydrophilicity and stability. The composite membrane can take water up to 819 times that of MPPM. The mass of assembled layers can maintain more than 94% after oscillating washing in 1.5 mol·L-1 NaCl solution or in 55℃ water for 48 h. The equilibrium adsorption experiments indicate that the ion-imprinted composite membranes exhibit high adsorption capability and high selectivity towards Cu(Ⅱ). The maximum adsorption capacity is 112.87 mg·cm-2

and the selectivity coefficients are 17.72

26.66

17.43

16.87

29.72 and 19.75 with Pb(Ⅱ)

Zn(Ⅱ)

Ni(Ⅱ)

Co(Ⅱ)

Mg(Ⅱ) and Mn(Ⅱ) as competing ions

respectively. The adsorption thermodynamics and kinetics show that the adsorption process of Cu(Ⅱ) is in monolayer adsorption and is dominated by chemical interaction. The ion-imprinted composite membranes exhibit good regeneration ability

and their adsorption capacity can be maintained over 90% even after ten adsorption-desorption cycles.