Fabrication of poly(amide-imide)-polyethersulfone dual layer hollow fiber membranes applied in forward osmosis by combined polyelectrolyte cross-linking and depositions

► Delamination-free UF dual layer hollow fiber has been fabricated as substrate. ► The substrate was modified to form a NF-like skin on outer layer for FO application. ► The modification involves cross-linking and polyelectrolyte depositions. ► High water flux can be achieved in FO process with high MgCl2 rejection up to 97%.