Effect of needle gauge on the morphology and performance of electrospun <scp>PAN</scp> / <scp>PSU</scp> nanofiber membranes

Abstract In the present work, we explored the impact of needle diameter (gauge) on the fiber diameter, uniformity, and performance of the membranes. We used four stainless steel needles with different gauges (24G, 26G, 28G, and 30G) to fabricate the membranes. The copolymers, polyacrylonitrile (PAN) and polysulfone (PSU), at a total concentration of 14 wt % (80% PAN and 20% PSU), were used to prepare the nanofiber membranes. The electrospinning process was conducted at 1 mL/h. polymer flow rate, 30 kV high voltage, 14 cm tip‐to‐collector distance. To evaluate the nanofiber membranes' diameter and morphology, membranes were characterized using scanning electron microscopy (SEM). The mechanical properties were assessed by measuring tensile strength, and the surface wettability was examined using contact angle measurements. The prepared nanofiber membranes were then tested for oil–water separation performance. Results showed that the needle gauge considerably affects fiber uniformity, mechanical strength, surface wettability, and separation efficiency. Larger needles (24G and 26G) formed thicker fibers and presented constant oil rejection (100%) through all cycles. These membranes reached higher water fluxes of (211) and (300) LMH, respectively, but showed varied mechanical integrity, lower contact angles (81) and (82), and lower porosity (81%) and (77%), reflecting slightly improved hydrophilicity. This study highlights the importance of needle selection in tailoring ES membrane properties to improve nanofiber membrane quality and production efficiency.