The development of high-performance and well-constructed thin-film composite (TFC) hollow fiber membranes for forward osmosis (FO) applications is presented in this study. The newly developed membranes consist of a functional selective polyamide layer formed by highly reproducible interfacial polymerization on a polyethersulfone (PES) hollow fiber support. Using dual-layer coextrusion technology to design and effectively control the phase inversion during membrane formation, the support was designed to possess desirable macrovoid-free and fully sponge-like morphology. Such morphology not only provides excellent membrane strength, but it has been proven to minimize internal concentration polarization in a FO process, thus leading to the water flux enhancement. The fabricated membranes exhibited relatively high water fluxes of 32-34 LMH and up to 57-65 LMH against a pure water feed using 2 M NaCl as the draw solution tested under the FO and pressure retarded osmosis (PRO) modes, respectively, while consistently maintaining relatively low salt leakages below 13 gMH for all cases. With model seawater solution as the feed, the membranes could display a high water flux up to 15-18 LMH, which is comparable to the best value reported for seawater desalination applications.
Electrically conducting elastomer fibers based on natural rubber (NR) and up to 10% w/w polyaniline (PANI) in its emeraldine base (EB) form were fabricated by a wet spinning process. The resulting fibers at various PANI contents were doped by immersion in aqueous HCl solution, which converted the PANI to the electrically conductive emeraldine salt (ES) form. The morphology of the composite fibers was studied by scanning electron microscopy (SEM). PANI particles were inhomogeneously distributed in the NR matrix. The electrical conductivity of the fibers increased with the increasing PANI-ES content and leveled off at a value of around 10 23 S/cm at PANI-ES concentration of 5% w/w. The fibers retained most of their elasticity upon doping, while the tenacity was somewhat reduced. Gratifyingly, the electrical conductivity of the new elastomer fibers was preserved upon elongational deformation, even if strains as large as 600% were applied.
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