High separation performance thin film composite and thin film nanocomposite hollow fiber membranes via interfacial polymerization for organic solvent nanofiltration

Abstract

Hollow fiber (HF) organic solvent nanofiltration (OSN) membrane has unique self-supporting structure and larger specific surface area over flat OSN membranes, which is much more beneficial for separation processes intensification in chemical related industries. The key of this technology is HF OSN membrane. However, the research works on HF OSN membranes was relatively less till now. In this work, an outer-skinned polyimide HF substrate membrane was spun, and then thin film composite (TFC) membrane was prepared via interfacial polymerization (IP) between ultra-low concentration m-phenylenediamine (MPD) in the aqueous phase and trimesoyl chloride (TMC) in the organic phase on the HF substrate surface, with sodium dodecyl sulfate (SDS) as aqueous additives and triethylamine (TEA) as aqueous catalyst, and subsequently accompanied by crosslinking and solvent activation procedures. Further, thin film nanocomposite (TFN) HF OSN membrane incorporated with graphene oxide (GO) was also prepared. The combination of lower MPD concentration with SDS and TEA as additives in the aqueous monomer solution promote the formation of a TFC HF OSN membrane with average roughness of less than 3 nm, and a rhodamine B (RDB) rejection close to 100%, together with an ethanol permeance higher than 12 L m−2 h−1 MPa−1 under the optimum fabrication conditions. The optimal TFN membrane at a doping GO content of 5.0 mg L−1 achieves up to 20 L m−2 h−1 MPa−1 for the ethanol permeance without sacrificing the RDB rejection (nearly 100%). Moreover, both HF OSN membranes possess good swelling resistance, which proves their application potential in organic solvent system.