Anion-exchange membranes for separation of borates by Donnan dialysis

► Polyethyleneimine grafted to microfiltration membrane to prepare anion-exchange membranes ► NaCl and Na2SO4 transported through prepared pore filled membranes faster than through polymer membranes. ► Polyethyleneimine shrinks in high ionic strength solutions and makes the pores open ► Donnan dialysis malfunctioning for pore filled PEI membranes.