The effect of 3D printing parameters on electrochemical properties of heterogeneous cation exchange membrane

Purpose The study aims to focus on the preparation of a heterogeneous cation exchange membrane by a three-dimensional (3D) method – fused filament fabrication using a series of nozzles of various diameters (0.4–1.0 mm). Polypropylene random copolymer (PPR) as a polymeric binder was mixed with 50 Wt.% of the selected conventional cation exchange resin, and a filament was prepared using a single screw mini extruder. Then filament was processed by FFF into the membranes with a defined 3D structure. Design/methodology/approach Electrochemical properties, morphology, mechanical properties and water absorption properties were tested. Findings Dependence of the tested properties on the used nozzle diameter was found. Both areal and specific resistances increased with increasing nozzle diameter. The same trend was also found for permselectivity. The optimal membrane with permselectivity above 90%, areal resistance of 8 O.cm2 and specific resistance of 124 O.cm2 was created using a nozzle diameter of 0.4 mm. Originality/value Using new materials for 3D print of cation exchange membrane with production without waste. The possibility of producing 3D membranes with a precisely defined structure and using a cheap 3D printing method. New direction of membrane structure formation. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies. 3D-printed heterogeneous cation exchange membranes were prepared, which can compete with commercial membranes produced by conventional technologies.

The Development of Electroconvection at the Surface of a Heterogeneous Cation-Exchange Membrane Modified with Perfluorosulfonic Acid Polymer Film Containing Titanium Oxide

One way to enhance mass transfer and reduce fouling in wastewater electrodialysis is stimulation of electroconvective mixing of the solution adjoining membranes by modifying their surfaces. Several samples were prepared by casting the perfluorosulfonic acid (PFSA) polymer film doped with TiO2 nanoparticles onto the surface of the heterogeneous cation-exchange membrane MK-40. It is found that changes in surface characteristics conditioned by such modification lead to an increase in the limiting current density due to the stimulation of electroconvection, which develops according to the mechanism of electroosmosis of the first kind. The greatest increase in the current compared to the pristine membrane can be obtained by modification with the film being 20 μm thick and containing 3 wt% of TiO2. The sample containing 6 wt% of TiO2 provides higher mass transfer in overlimiting current modes due to the development of nonequilibrium electroconvection. A 1.5-fold increase in the thickness of the modifying film reduces the positive effect of introducing TiO2 nanoparticles due to (1) partial shielding of the nanoparticles on the surface of the modified membrane; (2) a decrease in the tangential component of the electric force, which affects the development of electroconvection.