A graduate student of Shaovich Khan from the University of Lincheping (Sweden) designed a new filter for cleaning dirty or just salty water, which does not require energy costs for work. He uses the heat of sunlight and in passive mode constantly evaporates the liquid, dividing it into clean steam and impurities in the process. The principle is old, but in this filter it is implemented with the help of unusual material – thermal airgoel.
Khan took pulp as a common and extremely cheap material as a basis. It was turned into an airgel and applied on one side a coating of the Pedot: PSS organic polymer organic polymer. It is known for extremely effectively absorbs solar radiation, especially in the infrared, heat spectrum. As a result – the coating quickly heats up.
For better buoyancy, the airgel was placed on the base of porous material through which water can leak. It rises through the porcery and reaches an airgoel, where it heats up and evaporates. The process is far from instantaneous, but it proceeds 4-5 times faster than natural evaporation of water under the influence of the sun. The resulting steam settles on a special plate, then the condensate along the gutter flows into the container.
Such a filter can work endlessly while the sun shines, which makes it dependent only on the weather. True, the airgel itself must be periodically cleaned of accumulated impurities. But with regular cleaning, its service life is actually not limited, and such a technology will help to passively purify huge volumes of contaminated water.
Source — Linkoping University