Researchers demonstrate new alternative seawater desalination membrane

Access to freshwater is a significant problem for many people all around the world. In some areas, severe drought means there is no fresh drinking water, and in others, pollution is so heavy that the water is undrinkable. Making fresh drinking water from seawater has been possible for a long time, but researchers have recently shown a new alternative seawater desalination membrane that can make seawater drinkable in minutes.

The Korea Institute of Civil Engineering and Building Technology has announced the development of a stable performance electrospun nanofiber membrane able to turn seawater into drinking water using a membrane distillation process. Scientists on the project note that membrane wetting is the biggest challenge in membrane distillation. If the membrane exhibits wetting during the membrane distillation operation, the membrane has to be replaced.

Progressive membrane wetting has been observed in long-term operations, and once the membrane is fully wetted, it leads to inefficient distillation performance. The inefficient performance produces low-quality permeate. The research team developed a co-axial electrospun nanofiber membrane fabricated using an alternative nano-technology. The alternative technology is electrospinning, and the technology shows potential to help solve freshwater shortage problems worldwide.

The technology prevents wetting issues and improves the long-term stability for the membrane distillation process. The technique used to produce the material is the most favorable and simple option to fabricate membranes with three-dimensional hierarchical structures. The team used polyvinylidene fluoride-co-hexafluoropropylene as the core and silica aerogel mixed with a low concentration of the polymer as the sheath to produce a co-axial composite membrane.

They were able to obtain a superhydrophobic membrane surface. The team also notes that the silica aerogel showed much lower thermal conductivity than conventional polymers leading to increased water vapor flux during the membrane distillation process. The membrane performed at 99.99 percent salt rejection for one month. The team says the membrane operated well without wetting and fouling issues.