Electric field-enhanced assembly of polyelectrolyte composite membranes

In this paper, a novel method was developed to enhance the assembly of polyelectrolyte composite membranes by inducing an electric field during electrostatic adsorption process. The hydrolyzed polyacrylonitrile (PAN) ultrafiltration (UF) membrane was placed in between a capacitor setup. The polyethyleneimine (PEI) was compulsorily assembled on the PAN support under the action of external electric force. Subsequently, the polyelectrolyte composite membranes were evaluated by pervaporation separation of water and alcohol mixture. The membrane obtained with only one PEI layer had a separation factor of 304 and a permeate flux of 512 g/m2 h (75 °C) for pervaporation of 95 wt% ethanol–water mixture. An atomic force microscopy was also used to observe the microtopographical changes. The regularity of the membranes assembled by the new method was also improved in comparison with the membrane assembled by a dynamic layer-by-layer adsorption.