Facile, Dip Coating Fabrication of Polymeric Electropositive Membrane Filter Exploiting Electrostatic Interactions

Electropositive membrane effectively filters out ultrasmall pollutants, particularly viruses demonstrating a negative charge in water media through electrostatic interaction. Electropositive membrane filter is made of host membrane and electropositive particles decorating the membrane. In this study, for the first time, fabrication of an electropositive membrane was shown through simple dip coating of electropositive particles. Electronegative m-aramid membrane was rationally chosen as a host to harness the electrostatic interaction between host membrane and electropositive particles. Thus, through simple dipping of the membrane in boehmite suspension, electropositive boehmite nanorods could be successfully attached to the electrospun m-aramid membrane. Morphological analysis along with zeta-potential analysis verified the complete coverage of membrane by electropositive boehmite particles. Furthermore, solid filtration performance, way better than that of commercially available membrane filters, could be verified by rejection tests employing the different sizes of negatively charged polystyrene beads as virus surrogates. Interestingly, the electropositive boehmite/m-aramid membrane demonstrated ultrafiltration capability and a far superior water flux to common ultrafiltration membranes, which is comparable to that of microfiltration membrane. We believe that the dip coating fabrication strategy might be easily expanded to other properly chosen electronegative hosts/electropositive particle pairs. Additionally, a substantial reduction in fabrication cost might be achieved through continuous fabrication.