Preparation and characterization of new low MWCO ceramic nanofiltration membranes for organic solvents

• A ceramic membrane with a MWCO of 350 g/mol for organic solvents was developed.
• Complexation agents in the sol enhance the separation performance.
• Permporometry is a suitable tool for quality control of nanofiltration membranes.
• Rejections of ceramic membranes depends substantially on the specific solvent.

Ceramic membranes show advantageous behavior over polymeric membranes under harsh conditions including high pH, high temperature applications or applications involving organic solvents. However, in the range of organic solvent nanofiltration (OSN) the currently available membranes do just offer a molecular weight cut-off (MWCO) of 600 g/mol or above. Here, a new approach is presented to manufacture ceramic membranes with active layers of titanium dioxide/zirconium dioxide with integrated carbon on top of a tubular ceramic multi-layer support. Filtration tests of these membranes with polystyrene mixtures in THF reveal a MWCO of 350 g/mol, thus extending the range of possible nanofiltration applications. The paper also presents a new combination of characterization of the membranes with permporometry and filtration tests that demonstrate the importance of the supporting layers for the creation of a good nanofiltration membrane.