Researchers at the Smart Materials Laboratory (SML) and the Center for Smart Engineering Materials (CSEM) at New York University Abu Dhabi (NYUAD) have reported a new method for harvesting water from natural sources such as fog and dew.
In the course of the study, researcher Patrick Commins and doctoral student Maria B. Al-Khandawi observed for the first time the process of spontaneous condensation of water from vapor to liquid form and movement along the surface of an organic crystal that slowly sublimates. This was found to be caused by changes in the width of small channels that appear on the surface of the crystal over time, which direct the condensed water across the surface of the crystal.
In the article entitled Autonomous and directed water flow and particle transport on a dynamic sublimation crystal surface published in the journal Chemistry of nature, researchers describe the process of condensation and movement of water carrying particles on the surface of crystals of hexachlorobenzene, a compound often used as a fungicide. Thanks to sublimation, the surface of this material has a hard relief with certain parallel channels. Small solid particles such as dust or even metallic nanoparticles have been observed to move autonomously through the channels. The movement of these particles was found to be caused by condensed air water migrating through the channels due to changes in the cross-section and width of the channels over time.
Autonomous water flow has previously been achieved using either surface chemical modifications or precisely engineered microchannels, or on the surface of natural systems such as certain plants or insects. The findings of this new research could guide the creation of new technologies to harness natural water sources such as dew and fog, which are currently only used by some desert plants and animals for survival. The new study builds on the understanding of the water-harvesting mechanisms of such biological structures, while it presents a fundamentally different mechanism for water transport.
“The movement of water on solid surfaces is one of the most fundamental phenomena found in nature,” said Panche Naumov, head of the Smart Materials Laboratory and director of the Center for Smart Engineering Materials and corresponding author of the study. “Through millennia of evolutionary processes, the surfaces of natural organisms have been optimized to efficiently transport water for various life-sustaining functions. Plants have been observed to do this by moving water against gravity. Our team has discovered a new way to move water across a dynamic solid surface that is a fundamentally new principle for water harvesting. It could serve as inspiration for new technologies that could potentially maximize the efficiency of experimental systems used to harvest air moisture.”