Tunable multipurpose separation technology based on crosslinked dialdehyde-β-cyclodextrin and polyethyleneimine coating membrane

A tunable multipurpose separation technology was developed based on a membrane comprised of crosslinked dialdehyde-β-cyclodextrin (DA-β-CD) and polyethyleneimine (PEI). Since the DA-β-CD and PEI are hydrophilic, the coated membrane exhibits high hydrophilicity and underwater superoleophobic properties, and its oil/water emulsion separation efficiency reached 99.9 %, which increased 69.1 % comparing with the pristine PVDF membrane. In addition, the surface composition of the coated membrane is adjustable because both DA-β-CD and PEI can be used as the main functional component or crosslinking agent. Accordingly, if a large amount of the PEI and small amount of DA-β-CD are applied onto the membrane surface, the coated membrane exhibits excellent heavy metal ion and dye removal capabilities. The respective Cr6+ and Congo red (CR) rejection rates were 97.8 % and 98.6 % after filtration. If a large amount of DA-β-CD and a small amount of PEI is coated onto the membrane surface, the coated membrane exhibits superb phenol and bilirubin removal capabilities. The respective phenol and bilirubin rejection rates after filtration were 79.6 % and 84.1 %. Based on these findings, it is evident that the coated membrane presented tunable multipurpose. Furthermore, the coating layer is very stable thanks to the cross-linking reaction between DA-β-CD and PEI. This research provides a potential strategy for the treatment of wastewater in different situations via a tunable multipurpose separation technology.