Schematic for co-axial electrospinning device. Credit: ElsevierThe World Health Organization estimates that 785 million people lack access to clean drinking water. Even though there is a lot of water on Earth, the majority of it is seawater. Freshwater only accounts for 2.5%. Desalinating seawater is one way to make clean drinking water. Korea Institute of Civil Engineering and Building Technology has announced the creation of a stable performance electrospun microfiber membrane that can be used to transform seawater into water through membrane distillation.The most difficult problem in membrane distillation is membrane wetting. Membrane wetting is a sign that a membrane has been damaged or worn out. For long-term operations, progressive membrane wetting should be observed. A membrane that is too wet can cause inefficient membrane distillation performance. The membrane will also produce low quality permeate through its feed stream.Dr. Yunchul Woo is part of a research team at KICT that has created co-axial electrospun membranes made from nano-technology called electrospinning. This desalination technology has the potential of solving the world's water shortage. This technology is able to prevent wetting and improve the stability of membrane distillation. The nanofibers should form a three-dimensional hierarchical structure in membranes to provide higher surface roughness and better hydrophobicity.Co-axial electrospinning is one of the easiest and most efficient ways to make membranes with hierarchical three-dimensional structures. Dr. Dr. Silica aerogel had a lower thermal conductivity than conventional polymers. This resulted in increased water vapor flux and reduced heat losses during membrane distillation.The merits of co-axial electrospun microfiber membrane. Credit: ElsevierAlthough they had a high water vapour flux, most of the membrane distillation studies that used electrospun nanofibers were only for 50 hours. Dr. Dr. Woo's research group applied the membrane distillation process using fabricated coaxial electrospun microfiber membrane for 30 consecutive days. This is a period of 1 month.For one month, the co-axial electrospun microfiber membrane was able to reject 99.99% of salt. The membrane performed well in spite of wetting and fouling, owing to its low sliding angle, thermal conductivity, and other properties. One of the major drawbacks to membrane distillation is temperature polarization. Conductive heat losses can cause a decrease in water vapor flux performance during membrane distillation. It is ideal for long-term membrane distillation applications because it has several key characteristics, including low sliding angle, low thermal conductivity and avoiding temperature polarization. Additionally, it reduces wetting and fouling while maintaining high water vapor flux performance.Dr. Dr. Woo's research team found that stability is more important than high water vapor flux performance in commercially available membrane distillation processes. Dr. Dr. Woo stated that the co-axial electrospun microfiber membrane has strong potential to treat seawater solutions without wetting issues. It may also be suitable for pilot-scale or real-scale membrane distillation applications.Learn more Team ensures stability in desalination process using magnesiumInformation: Yun Chul Woo and colleagues, Co-axially-electrospun superhydrophobic membranes with 3D hierarchically-structured surface for long-term membrane dewatering, Journal of Membrane Science (2021). Yun Chul Woo et. al., Co-axially Electrospun Superhydrophobic Nanofiber Membranes with 3D-hierarchically Structured Surface for Desalination by Long-Term Membrane Distillation, (2021). DOI: 10.1016/j.memsci.2020.119028National Research Council of Science & Technology.
