The influence of water content in casting solution on the structure and performance of PES microfiltration membranes
Narrow pore size distribution polyethersulfone(PES)microfiltration(MF)membranes were prepared through vapor-induced phase separation(VIPS)coupled with non-solvent-induced phase separation(NIPS).In this study,PES was used as the membrane forming material,polyethylene glycol as the pore-causing agent,and water as the additive to prepare microfiltration membranes.The effects of the water content in the casting solution on the vapor exposure time and the structure and properties of microfiltration membranes in VIPS stage were investigated.The results indicate that as the water content in the casting solution increased from 0％to 3％,the required exposure time for achieving the same pore structure decreased from 90 s to 30 s.The pore size of the membranes was increased from 0.087 μm to 0.193 μm with a significantly narrower pore size distribution.The water contact angle increased from 83.6° to 113.2°,while the tensile strength and elongation at break improved from 1.86 MPa to 3.85 MPa and from 7％to 16％,respectively.Consequently,the pure water permeability increased from 5 840 L/(m2·h·MPa)to 42 300 L/(m2·h·MPa).These results suggest that the addition of a small amount of water in the casting solution significantly shortened the VIPS exposure time and improved the structure and performance of the MF membrane.
PES microfiltration membranevapor-induced phase separationwater contentunsteady statepore size distribution
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