An experimental comparative study on membranes used in air-gap membrane distillation (AGMD)
Paper ID : 1175-MST2015-FULL
Ali hatamnejad1, Javad Karimi-Sabet *2, Seyed Hamed Mousavi1, seyed mohammad ali moosavian3
1College of Engineering, University of Tehran, Tehran, Iran.
2P.O.Box: 14395-983, Tehran, Iran.
3University College of Engineering, University of Tehran, Tehran, Iran
Membrane distillation (MD) is an emerging and promising technique aimed at separating non-volatile components such as salts from aqueous feed streams. One of the major obstacles for MD application is the lack of an optimized MD membrane that can produce a high and stable flux in long-term operation. Generally, MD membranes should be highly hydrophobic, highly porous with high liquid entry pressure (LEP) and adequate mechanical strength to obtain high and stable flux. To obtain an appropriate membrane for AGMD a compromise between the impressive properties should be made by comparing different membrane features. In this paper, the performance of various synthesized membranes were assessed in AGMD under same operating conditions. These membranes have been characterized by a series of methods including: scanning electron microscopy (SEM), contact angle, porosity, LEP, and flux and finally benchmarked against commercial microporous PVDF flat-sheet membrane. The membranes studied included a neat polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) electrospun membrane, a neat PVDF-HFP phase-inversion membrane, a dual-layer electrospun PVDF-HFP/polyacrylonitrile (PAN) membrane and a commercial PVDF membrane. The results showed that dual-layer membrane had much better flux performance compared to neat electrospun membrane, phase-inversion PVDF-HFP membrane and commercial PVDF membrane (17.6, 13.4, 9.3 and 8.5 L/m2h, respectively). Compared to membranes fabricated by traditional phase-inversion technique including commercial membranes, electrospun single and dual-layer membranes had 17% higher porosity (80% and 78%, respectively), 21% higher hydrophobicity (140°) and consequently about 40% higher flux (13.4 and 17.6 L/m2h, respectively), while LEP of the electrospun membranes (104 and 109 kPa, respectively) were not adequate enough compared to the phase-inversion and commercial membranes (182 and 204.8, respectively).
membrane distillation (MD), electrospun membrane, nanofiber, dual-layer, PVDF-HFP
Status : Paper Accepted (Oral Presentation)