The design process is based on transpiration, a process found in nature by which trees pump up water through their trunks
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Spotted: While solar stills can already produce drinking water from unclean or salty sources, engineers at Virginia Tech have come up with an improved method. The engineering team created a tree-like solar still for water purification, that simulates the natural process of water moving up via roots and stems into leaves. Inspired by mangroves, the design takes on the form of a ‘synthetic tree’.
The majority of current devices rely on a process capillary action, where liquid adheres to the borders of a small area and drags other molecules upwards due to the liquid’s internal cohesion. However, this process does not scale very well, and the new design is based on a different process called ‘transpiration’.
Through transpiration, plants can effectively absorb water from their roots and transport it through their trunks to their branches. The mechanism relies on a suction effect, where water is pulled up by the decreased water potential in the air surrounding the plant. The water is then expelled through the leaves through vaporisation.
Inspired by this natural process, the synthetic tree consists of 19 plastic tubes 6 centimetres high with a 3.175 millimetre diameter each. As water goes up the tubes, it goes through a porous ceramic disk coated in graphite which has a leaf-like function and provides an evaporating surface.
“The ultimate goal is to achieve a suction pressure strong enough to pull ocean water through a salt-excluding filter without requiring a mechanical pump, analogous to how mangrove trees are able to grow in ocean water,” explains co-researcher Jonathan Boreyko.
Future work will involve testing the mechanisms with taller trees, adding more leaves, and using membranes to filter salt out of the water, the engineers explain.
Written By: Katrina Lane