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The layer-by-layer (LBL) polyelectrolyte deposited membranes have drawn increasing attention in various applications due to the ease of selective layer formation and their stability and versatility. In this study, the LBL deposition was performed at the inner surface of the polyethersulfone (PES) hollow fiber substrate to form composite nanofiltration (NF) membrane. The semi-dynamic deposition procedure was adopted with the aid of syringes. The newly developed inner deposited (id-LBL) membranes were then tested in NF and forward osmosis (FO) applications and the performance were compared with outer surface deposition as well as some literature data. The id-LBL membranes could not only withstand higher operating pressure but also possess superior hardness rejection especially in high concentration mixed salt solutions (more than 95% rejection to Mg 2+ and Ca 2+ in a 5000 ppm total dissolved salt (TDS) mixture under 4.8 bar). As for the FO process, with only two layer deposition, the id-LBL membranes also demonstrated significant performance improvement with increased water flux (up to 70 L/m 2 h using 0.5 M MgCl 2 as draw solution in active layer facing draw solution configuration) and reduced salt leakage (around 0.5 g/m 2 h using 1 M MgCl 2 draw solution in active layer facing feed water configuration). This study suggests that for hollow fiber substrate, the inner surface is more suitable for the formation of the selective layer via LBL deposition than the outer surface. [ABSTRACT FROM AUTHOR]

Developing an effective and economical technology to achieve the recovery of catalysts in the process of organometallic synthesis has attracted significant attention. Herein, a novel functional fiber catalyst with bispyridine structure was successfully constructed by modifying the commercial polyacrylonitrile fiber. Modified bidentate ligand fiber-based can be used to efficiently complexe Cu(II). The functional fibers were fully characterized by FTIR, ICP, XPS, XRD, SEM, and TGA. To verify the catalytic activity of PAN bis(Py)-Cu(II) F, A3 coupling reaction was applied in this work. The results showed that only 0.1 mol% catalyst dosage was needed and the maximum isolated yield was up to 99%. Recycle experiments showed that PAN bis(Py)-Cu(II) F has fine recycling performance, and there is no decrease in catalytic efficiency during the first six cycles. Consequently, as a recyclable functional fiber catalyst based on commercial polyacrylonitrile fiber, it provided a new insight for green synthesis and industrial production. [Display omitted] • Novel bispyridine functionalized polyacrylonitrile fibers serve as bidentate ligand to complexe Cu(II). • PAN bis(Py)-Cu(II) F has well structural and thermal stability. • Low necessary catalyst dosage (0.1 mol%) with wide substrate application range (12 examples, up to >99% isolated yield). • PAN bis(Py) F could withstands 6 times of use without deactivation in catalytic activity. [ABSTRACT FROM AUTHOR]