Polystyrene‐Modified <scp>PVDF</scp> Membranes: A Novel Approach for Improved Flux and Salt Rejection in Direct Contact Membrane Distillation

Abstract

ABSTRACT In this study, novel mixed‐matrix membranes based on polyvinylidene difluoride (PVDF) blended with varying ratios of polystyrene (PS) were fabricated and evaluated for use in direct contact membrane distillation (DCMD). Membrane morphology, crystallinity, and surface properties were characterized using SEM, XRD, and contact angle measurements. The incorporation of PS enhanced hydrophobicity and improved crystalline structure without altering the α‐phase of PVDF. The performance of the membranes was systematically optimized under varying operating conditions including feeding temperature, flow rate, operational time, and salt concentration. Notably, the membrane with 2 wt.% PS exhibited the highest water vapor flux (10 kg/m 2 h) and salt rejection (&gt; 99.9%) at a feed temperature of 80°C and a concentration of 10,000 ppm of NaCl. Extended operation up to 24 h demonstrated long‐term stability and wetting resistance. Compared to other modified PVDF membranes in the literature, the developed PVDF–PS membranes offer competitive performance. The enhancement in performance is attributed to the hydrophobic and structural effects of PS, which promote crystallinity in the PVDF matrix. This work introduces an effective, low‐cost modification strategy to improve membrane efficiency for desalination applications, suggesting that PVDF–PS membranes are promising candidates for scalable DCMD systems.