Fabrication of high performance and durable forward osmosis membranes using mussel-inspired polydopamine-modified polyethylene supports

A thin film composite (TFC) forward osmosis (FO) membrane with high performance and superb durability was fabricated on a polydopamine (PDA)-modified polyethylene (DPE) support via an unconventional aromatic solvent-based interfacial polymerization (IP) method. The PDA coating uniformly hydrophilized the hydrophobic pristine polyethylene (PE) support, which enabled the long-term operation stability. The thin (similar to 8 mu m) and highly porous support structure with interconnected pores was preserved after the PDA modification, leading to a remarkably low structural parameter (similar to 168 mu m) of the support. In addition, the use of the toluene-based IP process allowed for the formation of a highly permselective polyamide selective layer on the hydrophilic DPE support, which was challenging with the conventional aliphatic solvent-based IP process. Hence, the prepared DPE-supported TFC (DPE-TFC) membrane exhibited unprecedented high FO performance, i.e., similar to 4.5 times higher FO water flux and similar to 63% lower specific salt flux (in FO mode) compared to the commercial HTI-CTA membrane. Furthermore, the DPE-TFC membrane possessed superior mechanical robustness, which guarantee durable operability and potential application even in mechanically harsh environments. Hence, the PE-supported FO membrane presents a new paradigm in FO membrane technology.