Characterisation of nanofiltration membranes: Structural analysis by the DSP model and microscopical techiques

The Donnan steric pore model in the simplified and integrated version, proposed by Bandini et al., has been used to obtain the pore size and membrane thickness along with the charge concentration for a PCI nanofiltration membrane (AFC-80). This has been done by fitting the experimental results on retention versus flux for NaCl aqueous solutions. Pore size and equivalent membrane thickness (thickness to porosity ratio) have been confirmed also by fitting for a cyclohexanone solution. Charge has been seen to follow a Freundlich isotherm. The structural parameters fitted by the model showed a good agreement with those obtained from AFM including pore radius, thickness and porosity. Water permeability has also been correctly predicted.