Omniphobic Nanofibrous Membrane with Bioi-nspired Nanoflower-on-nanoneedle Double Re-entrant Structure for Enhanced Performance in Membrane Distillation
DescriptionDespite the growing recognition of membrane distillation (MD) as a potential solution for today’s demands for water reclamation and zero liquid discharge (ZLD), especially for challenging industrial wastewaters and hypersaline brines, the MD process has yet to achieve commercialization. One major reason is that, although ongoing research has led to many advances in membrane technology, there has yet to be developed a sufficiently cost-efficient and high performing MD membrane that could endure long-term operations without exhibiting low permeate flux and serious pore wetting.A good candidate is electrospun nanofibrous membranes (ENMs), as they are relatively inexpensive, highly flexible, and have highly microporous morphologies. However, the growing research on MD membranes have shown that the improvement of the membrane’s surface roughness to endow hydrophobicity and/or superhydrophobicity is not enough for achieving sufficient anti-wetting and anti-fouling properties. What is also required is the development of specific surface nanostructures with omniphobicity, particularly “re-entrant” micropillar structures, or better yet, “double re-entrant” mushroom-like structures. However, studies have yet to report the successful fabrication of double re-entrant ENMs.In this regard, we are inspired by studies in material science and chemistry that have successfully “grown” hierarchical nanograss and nanoflower structures on a copper-based substrate. Although there exist studies on “attaching (coating)” nanorods on the flexible polymeric nanofibers of MD membranes, to the best of our knowledge, no previous MD studies have attempted to “grow” double reentrant nanostructures on nanofibers. The advantages of growing these nanostructures are that 1) they become an organic part of the nanofibers, and as such, there is less probability of their detachment from the membrane, and 2) there is no need for fluorination, a process which poses potential environmental and health risks. Thus, we propose to grow a double re-entrant nanostructure consisting of nanoflowers and nanoneedles on a copper based electrospun membrane by optimizing the polymer viscosity, electrospinning process, reaction time, and temperature.The simple method combining electrospinning and in-situ growth used for fabricating this membrane will provide a new approach for designing hierarchical nanostructures on porous ENMs surfaces. We also plan to illuminate how these nanostructures relate to MD performance through a systemic, long-term MD study using an in-house developed wetting detection system. We anticipate our omniphobic, bioinspired nanoflower-on-nanoneedle double re-entrant membrane with enhanced mechanical stability and environmental sustainability will expand the versatility of MD membranes and move MD closer toward commercialization.
|Effective start/end date||1/01/23 → …|