Development of high-performance electrospun nanofiber based forward osmosis membrane by introducing graphene oxide‑calcium carbonate particle composite intermediate layer

Interlayer construction is considered as an attractive strategy for optimizing the performance of electrospun nanofiber (ENs) based forward osmosis (FO) membranes due to its outstanding effect on the regulation of surface roughness and pore size on substrates. Herein, calcium carbonate (CaCO3) particles were uniformly coated on the surface of graphene oxide (GO) interlayer and acted as sacrificial materials to induce the formation of high-performance polyamide (PA) active layer. The presence of CaCO3 particles was effective for promoting the formation of more polyamide and tuning the microstructure of PA active layer, attributing to the reaction between CaCO3 particles and H+ ions generated from the interfacial polymerization (IP) process in which numerous CO2 nanobubbles were simultaneously released on the reaction interface. The formed PA active layer on the optimized FO membrane had a highly loose and crater-like structure as well as the highest cross-linking degree, providing the membrane with superior performance on both water flux and specific salt flux compared to other previously reported FO membranes supported on nanofibrous substrates. This work offered a new technique route for the fabrication of high-performance ENs-based FO membranes through constructing a composite interlayer having the direct regulatory function on the microstructure of PA active layer.