Tailoring the Morphology and Performance of Polyacrylonitrile Ultrafiltration Membranes for Produced Water Treatment via Solvent Mixture Strategy

Abstract

AbstractThe separation performance of membranes is highly dependent on their morphology and microstructure. The present study aims to tailor the characteristics of asymmetric polyacrylonitrile (PAN) ultrafiltration membranes by adopting a solvent mixture strategy, combining dimethylformamide (DMF) and N‐methyl‐2‐pyrrolidone (NMP) for produced water treatment. The ternary phase diagram was used for better analysis of the microstructural changes from the thermodynamics point of view. Using a solvent mixture containing more DMF (i.e., 75 %) and increasing the PAN concentration in the dope were effective in improving the solution viscosity and promoting delayed demixing. As a result, finger‐like macrovoids were suppressed to some extent and the internal morphology of the membranes was transformed into a sponge‐like structure, accompanied by a reduction in the overall membrane porosity and mean pore size.