Enhancing oil–water emulsion separation using improved styrene–acrylonitrile copolymer membrane: Experimental and thermodynamic study of the impact of solvent mixtures

Abstract

This study investigated the fabrication of styrene–acrylonitrile copolymer (SAN) membrane using the nonsolvent‐induced phase separation (NIPS) method with a combination of solvents, namely N‐methyl‐2‐pyrrolidone (NMP) and dimethylformamide (DMF) and water as the nonsolvent. Since the impact of varying solvent ratios on SAN membrane performance remained unexplored, this study aimed to address this knowledge gap in the context of oil–water emulsion separation. Experimental results demonstrated that employing a solvent mixture, rather than a pure solvent, led to improved membrane performance. The primary objective of this work was to experimentally determine the optimal solvent ratio for enhancing SAN copolymer membrane performance. Additionally, the Flory–Huggins thermodynamic model was applied to investigate the possibility of predicting membrane binodal data. The thermodynamic analysis revealed a strong agreement between calculated and experimental binodal data, with an error of less than 3.8%. Notably, membranes produced with an equal solvent ratio exhibited the most hydrophilic properties, resulting in increased permeability. The permeate flux for distilled water reached 320 L/(m2 h) (LMH), and water contact angle of the membrane was 22°. Furthermore, mechanical resistance increased up to 50%. These results highlight the promising potential of fabricating SAN membrane using solvent mixtures for oil–water emulsion separation.