Light Can Make Water Evaporate Without Heat and Could Enable New Approaches to Desalination
taylorvich writes:
https://techxplore.com/news/2023-10-evaporate-enable-approaches-desalination.html
Evaporation is happening all around us all the time, from the sweat cooling our bodies to the dew burning off in the morning sun. But science's understanding of this ubiquitous process may have been missing a piece all this time.
In recent years, some researchers have been puzzled upon finding that water in their experiments, which was held in a sponge-like material known as a hydrogel, was evaporating at a higher rate than could be explained by the amount of heat, or thermal energy, that the water was receiving. The excess has been significant-a doubling, or even a tripling or more, of the theoretical maximum rate.
After carrying out a series of new experiments and simulations, and reexamining some of the results from various groups that claimed to have exceeded the thermal limit, a team of researchers at MIT has reached a startling conclusion: Under certain conditions, at the interface where water meets air, light can directly bring about evaporation without the need for heat, and it actually does so even more efficiently than heat. In these experiments, the water was held in a hydrogel material, but the researchers suggest that the phenomenon may occur under other conditions as well.
Journal Reference:
Yaodong Tu, Jiawei Zhou, Shaoting Lin, and Gang Chen, Plausible photomolecular effect leading to water evaporation exceeding the thermal limit, PNAS, 120 (45) e2312751120 https://doi.org/10.1073/pnas.2312751120
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