Superhydrophobic PVDF–PTFE electrospun nanofibrous membranes for desalination by vacuum membrane distillation

• Published in: Desalination 2014-08, Vol.347, p.175-183
• Main Authors: Dong, Zhe-Qin, Ma, Xiao-hua, Xu, Zhen-Liang, You, Wen-Ting, Li, Fang-bing
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Desalination; Drinking water and swimming-pool water. Desalination; Electrospining; Electrospinning; Exact sciences and technology; Flux; Mathematical models; Membrane distillation; Membrane separation (reverse osmosis, dialysis...); Membranes; Nanofibrous membrane; Nanostructure; Pollution; Polytetrafluoroethylenes; PVDF–PTFE; Scaffolds; Superhydrophobic; Water treatment and pollution
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2014.05.015

In this study, a superhydrophobic nanofibrous membrane was prepared on the basis of an electrospun polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) nanofibrous scaffold coupled with a microporous PTFE substrate. The PVDF–PTFE nanofibrous scaffold was fabricated by electrospining of PVDF–PTFE blend solutions, it was observed that by changing the PTFE micro-powder content in the dope solutions from 0wt.% to 12wt.%, the water contact angle (WCA) and the liquid entry pressure (LEPw) of the membrane vary from 130.4° and 84kPa to 152.2° and 137kPa, respectively. The superhydrophobic PVDF–PTFE nanofibrous membrane was then tested for desalination by vacuum membrane distillation (VMD), a stable flux of 18.5kg/m2h and salt rejection higher than 99.9% was presented throughout the entire testing period of 15h, indicating the great potential of the PVDF–PTFE nanofibrous membranes in VMD. For further application of the PVDF–PTFE nanofibrous membranes in VMD, a mathematical model was presented to predict the vapor flux of the novel membrane under various operation conditions. A good agreement between the experimental and theoretical values for vapor fluxes was obtained; the results indicated that the VMD flux increased with the increase of feed temperature and flow rate and decreased with the increase of permeate pressure. •PVDF–PTFE electrospun nanofibrous membranes (ENMs) were fabricated by electrospining.•The ENMs with different PTFE micro-powder contents were prepared and characterized.•The PVDF–PTFE electrospun nanofibrous membranes were superhydrophobic.•The ENMs were used for desalination via vacuum membrane distillation.•The ENMs presented a high permeate flux with stable performance.