Enhancing the Performance of Polyacrylonitrile (PAN) Ultrafiltration Membranes via Alkaline Hydrolysis: Effect of Polymer and NaOH Concentrations

Polyacrylonitrile (PAN) is one of the most widely used polymeric materials for ultrafiltration (UF) membranes because of its excellent chemical stability, mechanical strength, and ease of fabrication. However, the intrinsic hydrophobicity of PAN limits its water permeability and increases its susceptibility to membrane fouling. In the present study, the performance of PAN ultrafiltration membranes was improved through alkaline hydrolysis using sodium hydroxide (NaOH). Initially, flat-sheet PAN membranes containing ۱۰, ۱۱, ۱۲, and ۱۳ wt% polymer were fabricated via the non-solvent induced phase separation (NIPS) technique. The fabricated membranes were subsequently hydrolyzed using ۲ and ۴ wt% NaOH solutions to enhance their surface hydrophilicity. The influence of polymer concentration and hydrolysis conditions on membrane wettability and filtration performance was systematically investigated by measuring water contact angle and pure water flux.The results revealed that membrane properties were strongly dependent on both PAN concentration and hydrolysis conditions. Among the pristine membranes, the membrane prepared with ۱۲ wt% PAN exhibited the most favorable balance between membrane morphology and water permeability with flux of ۴۷.۸ LMH. Following alkaline hydrolysis, a significant reduction in water contact angle accompanied by an increase in pure water flux was observed, confirming the successful enhancement of membrane hydrophilicity. The membrane hydrolyzed in ۴ wt% NaOH showed the lowest contact angle (approximately ۲۶°) and the highest pure water flux of ۷۳.۵ LMH, indicating the optimum hydrolysis condition among the investigated samples. The enhanced hydrophilicity is also expected to improve the membrane's resistance to fouling by reducing interactions between the membrane surface and potential foulants.Overall, this study demonstrates that alkaline hydrolysis is a simple, cost-effective, and scalable surface modification strategy for improving the hydrophilicity and permeability of PAN ultrafiltration membranes, providing a promising approach for water treatment applications.

کلیدواژه ها:

Polyacrylonitrile ، Ultrafiltration membrane ، Alkaline hydrolysis ، Sodium hydroxide ، Hydrophilicity ، Contact angle ، Pure water flux