Solubility parameter estimation and phase inversion modeling of bentonite‐doped polymeric membrane systems

Effects of bentonite concentration on morphology and permeation characteristics of bentonite‐doped polysulfone membranes were investigated. Solubility sphere for bentonite was constructed to estimate its solubility parameter. Thermodynamic modeling of phase inversion of this system was carried out using Flory–Huggins theory. The trade‐off between thermodynamic and kinetic parameters was used to predict the membrane morphology for bentonite concentration varying from 0 to 5 wt %. The porosity of bentonite‐doped membranes decreased up to 3 wt % that increased thereafter. Morphological analysis showed dense cross section with finger‐like macrovoids at 3 wt % beyond which it changed to honeycomb structure with large circular voids. Permeability of 3 wt % membrane was the lowest (5.6 × 10−12 m/Pa s) with 95% bovine serum albumin rejection. Contact angle of the membranes decreased from 83 to 66° with bentonite addition making the membrane more hydrophilic.