Commercial Nanofiber Nonwoven As a Support for Thin Film Composite Membrane for Forward Osmosis

Product scale-up for any new emerging technology is key to seeing that technology succeed. Forward osmosis (FO) is one such technology that has been struggling to be a commercially viable technology.  A major impediment to this is associated with the challenges that are there due to membrane manufacturing. Those companies that have seen some success with FO scale-up have developed FO membranes that resemble conventional RO membranes, though having certain chemical or structural differences. Many of the highly novel membranes, such as those widely discussed in the academic literature, will likely never see commercial reality because of the challenges associated with making those membranes in large quantity.  Electrospun nanofiber supported thin film composite membranes are generally thought to belong to this group.  Nanofibers have the properties sought after in FO TFC membrane support materials (high porosity, low tortuosity), and these membranes have shown great promise in the academic literature. However, the production of nanofiber mats at scale has been criticized.  Only recently has industrial scale production of nanofibers from companies like DuPont, Donaldson, and Hollingsworth & Vose brought nanofiber membranes into the commercial space.  In this work, we demonstrate the use of a commercial nanofiber nonwoven based support media to manufacture thin film composite (TFC) membranes for forward osmosis. We evaluate the viability of this material by comparing it to laboratory grade nanofiber based TFC membranes and commercially available solution casted TFC membranes. The fiber diameter of the nanofiber mat ranges from 445± 135 µm. ATR-FTIR spectrum confirms the successful formation of a polyamide selective layer by in-situ polymerization process and SEM imaging demonstrates the uniformity of the polyamide layer. The TFC membrane has a very high Young’s modulus, equivalent tensile strength, and low ductility as compared to a laboratory grade nanofiber based TFC membrane. The TFC membrane generates two times more water flux and ten times less reverse solute flux as compared to a commercial HTI solution cast TFC membrane. These results prove that the commercial nanofiber support is capable of producing better membranes than commercial HTI TFC membrane while maintaining similar standards as the laboratory grade nanofiber supported TFC membrane.