3D printed electrically conductive interdigitated spacer on ultrafiltration membrane for electrolytic cleaning and chlorination

Membrane fouling is one of the challenging issues surrounding membrane-based separation. Here in, we demonstrate direct 3D printing of electrically conductive interdigitated spacer on an ultrafiltration membrane for membrane cleaning and chlorination via periodic electrolysis. The spacers were 3D printed on the membrane surface via material extrusion using a composite slurry of graphite and silver. This 3D printed spacer, which was found to be mechanically robust, promoted turbulence, and increased the permeate flux. Moreover, as the potential is applied across the spacer segments in the presence of saline water, bubbling at the cathodic segment due to hydrogen evolution causes physical removal of the foulant from the membrane surface leading to flux recovery. In parallel, chlorine evolves at the anodic segment which decomposes the organic foulants and can potentially disinfect the membrane. Therefore, direct 3D printing of electrically conductive spacers on the membrane offers four benefits simultaneously: (1) spacer effect by promoting turbulence, (2) in-situ membrane cleaning, (3) in-situ chlorination, and (4) a reduced build-envelope due to the integration of both anode and cathode with the membrane as spacer. Our work, therefore, demonstrates dual-action in-situ membrane cleaning while simplifying the design of the membrane module.