Fabrication of phenolic resin membrane with polyvinyl alcohol fiber skeleton by electrospinning for organic solvent nanofiltration

As an emerging separation technology, organic solvent nanofiltration (OSN) has shown great potential in the chemical, food, and pharmaceutical industries. Considering the excellent solvent resistance of phenolic resin (PR), it has great potential to be employed for the fabrication of OSN membrane. However, the extremely low permeance due to the highly cross-linked network and limited fabrication strategies still hold back the further application of PR. Herein, we develop a novel method to fabricate PR membrane with polyvinyl alcohol (PVA) fiber skeleton for OSN. This is accomplished through the electrospinning of PVA-resol solution, followed by heating to initiate the cross-linking of resol to form PR. After the further reaction with glutaraldehyde (GA), the PR OSN membrane is finally acquired. Benefiting from the homogeneous mixing of PVA with resol in the electrospinning solution, the formed PVA fibers are uniformly embedded in the PR matrix. The space between PVA fiber skeleton with PR matrix could provide additional channels for the transportation of solvent molecules. Compared with those membranes fabricated by traditional casting methods, the permeance of PR/PVA/GA reported here is significantly improved. The molecular weight cut-off (MWCO) of PR/PVA/GA is about 803 Da based on the rejection curve. Meanwhile, the permeance of acetonitrile about 1.3 Lm(-2)h(-1)bar(-1) is the highest among the studied solvents, while the values are very low for nonpolar solvents, such as hexane and toluene. Additionally, the obtained membrane exhibits excellent anti-compaction ability and long-term stability. As an alternative to phase inversion and interfacial polymerization, the strategy reported here may provide a new way for the assembly of polymers into nanofiltration membranes for diverse separation applications.