A nanofiber membrane could help solve the drinking water crisis

Korean scientists claim a new desalination technique makes sea water fit to drink in minutes. The researchers used a membrane distillation process that resulted in 99.9 percent salt rejection for one month. If commercialized, they say the solution could help alleviate the drinking water crisis exacerbated by climate change. More than 3 billion people worldwide are affected by water shortages, with the amount of fresh water available for each person plunging by a fifth over two decades, according to the UN.

The new study details a way to purify sea water using a a nanofiber membrane as a salt filter. While scientists have used membrane distillation in the past, they kept encountering a massive obstacle that slowed down the process. If the membrane became too wet, or flooded, it could no longer reject the salt. Needless to say, this was a time-draining process that forced scientists to either wait for the membrane to dry or come up with additional solutions, like using pressurized air to release trapped water from its pores.

To overcome this challenge, the Korean team turned to a nano technology known as electrospinning to create their three-dimensional membrane. In scientific terms, they used poly vinylidene fluoride-co-hexafluoropropylene as the core and silica aerogel mixed with a low concentration of the polymer as the sheath to produce a composite membrane with a superhydrophobic surface. In essence, this created a filter that had a higher surface roughness and lower thermal conductivity, allowing it to desalinate water for up to 30 days. The full report was published in the Journal of Membrane Science.

“The co-axial electrospun nanofibre membrane has strong potential for the treatment of seawater solutions without suffering from wetting issues and may be appropriate for real-scale membrane distillation applications,” Dr Yunchul Woo, a materials scientist at the Korea Institute of Civil Engineering and Building Technology, said. He added that the membrane may be appropriate for "pilot-scale and real-scale membrane distillation applications.”

Currently, the main method of purifying sea water is through reverse osmosis at the roughly 20,000 desalination plants around the world. But these facilities require vast amounts of electricity to operate and also create concentrated brine as a waste product, which is typically dumped back in the sea. Therefore, it's no wonder scientists are exploring new solutions that aren't as counter-productive.