Sustainable air gap membrane distillation using recycled acrylic (RA) membranes: Application to Shatt Al-Arab water desalination

One of the research motivations in the MD field is to develop high-performance membranes by preparing hydrophobic membranes due to their high throughput and rejection. The current work focuses on the fabrication and performance evaluation of electrospun nanofiber membranes using recycled acrylic (Polymethyl Methacrylate) (RA) via air gap membrane distillation (AGMD). Recycling this material not only reduces plastic waste and pollution, but it also offers a low-cost alternative to virgin polymers, which aids in membrane fabrication. Scanning Electron Microscopy (SEM) confirmed a uniform, highly porous nanofibrous structure with interconnected pores in the prepared nanofiber membranes. Atomic Force Microscopy (AFM) revealed a rough surface morphology, while water contact angle measurements exceeding 121° indicated excellent hydrophobicity, critical for effective liquid-vapor separation. Fourier-transform infrared spectroscopy (FTIR) verified the preservation of key ester functional groups, confirming the chemical integrity of the RA. The assessments revealed that the electrospun nanofibers demonstrated considerable flexibility while preserving their structural and surface characteristics as evaluated through mechanical strength testing. The resulting membranes were utilized in a water desalination process employing an AGMD setup, tested under varying feed temperatures (45, 55, and 65°C) and flow rates (0.2, 0.3, and 0.4 L/min) to evaluate their impact on desalination efficiency. It was observed that increasing the feed temperature significantly boosted water flux; moreover, the feed flow rate notably improved permeate flux within AGMD systems, thereby enhancing mass and heat transfer capabilities. The highest permeate flux recorded was approximately 19 kg/m²·hr, achieved at a temperature of 65°C with a flow rate of 0.3 L/min and a salt rejection rate of 99.999%. Consequently, this study's results indicate that RA-based nanofiber membranes hold potential for sustainable and effective water desalination. Furthermore, AGMD proved to be highly efficient in salt removal from the Shatt al-Arab river and may serve as a viable solution for providing clean drinking water in southern Iraq.