Desalination by reverse osmosis to make water drinkable | News
Four students in the United States have designed a bottle of desalination water. The currently hypothetical device would be compact and portable.
Their design is inspired by mangrove trees, which use thermal and membrane desalination techniques to grow in salt water in the tropics. It includes an inlet chamber, which users fill with salt water, connected to a reverse osmosis membrane. The water filters through the membrane into an intermediate chamber connected to a synthetic sheet. The sheet consists of a nanoporous membrane on a microporous mesh. During evaporation, the water meniscus inside the pores become concave, resulting in a negative pressure difference between the inside and the outside of the surface. This creates suction that can overcome reverse osmosis at the filter, resulting in desalination.
The group says the design has several advantages over existing work on synthetic trees. They added a solar vane around the bottle to speed up the rate at which water would flow through the filter. This would increase the sweat rate, ensuring the process is faster than previously reported devices. The bottle is intended for personal and community use by people who do not have sufficient access to drinking water; the proposed single column structure ensures the portability of the device.
As the design is only preliminary, the next step for the team would be to create a prototype. Building a physical device would involve meeting the challenge of material costs to ensure that the device is accessible to intended users.
A one-slide summary of this article with questions to use with your 14-16 year old students: rsc.li/3MpVAi2
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