Highly Permeable Polymer Membranes Containing Directed Channels for Water Purification

This viewpoint describes the concept of using nanocomposite barrier layers containing directed water channels to increase membrane permeability for water purification. In one practical approach, the channels, formed at the interface between the interconnected nanofibrous scaffold and the polymer matrix, were used to guide the transport of water molecules in a directed manner and to also exclude contaminant molecules. This concept was demonstrated by embedding overlapped oxidized multiwalled carbon nanotubes into the poly(vinyl alcohol) (PVA) barrier layer for ultrafiltration (UF). We anticipate that the same approach can be extended by substituting oxidized carbon nanotubes with ultrafine cellulose nanofibers (diameter about 5 nm), which are derived from wood pulp and are environmentally friendly as well as more cost-effective, into highly cross-linked polymer barrier layers. The resulting thin-film nanofibrous composite (TFNC) membranes should exhibit a permeation flux significantly higher than those of conventional thin-film composite (TFC) membranes for nanofiltration while maintaining the same rejection capability.