Crystalline surface

Source: Courtesy of NYUAD

The particles on the surface of the hexachlorobenzene crystal are picked up by condensing water droplets and carried off as the material sublimes and the channel widens

A new way to harvest water from the air has been observed on subliming organic crystals. Similar techniques are used by some desert plants and animals. The Namib Desert beetle, for example, condenses fog via an array of hydrophilic bumps across the waxy superhydrophobic surface on its back that then funnels it into its mouth.

This is the first time researchers have observed water spontaneously condensing and moving across the surface of a slowly subliming organic crystal. ‘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 guide the condensed water across the crystal’s surface,’ the researchers from the New York University Abu Dhabi in the United Arab Emirates note. They suggest that this could be a novel way of combating water scarcity across the globe, particularly in desert areas. The condensation observed occurs on the surface of crystals of hexachlorobenzene.

Small solid particles like dust or even metallic nanoparticles were also seen to move along the channels. This was the result of being carried off by the water flowing through the channels in the crystal’s surface that widen over time as it sublimes.

Having discovered a new way to move water across a dynamic solid surface the researchers suggest that this work could inspire emerging technologies that could maximise the efficiency of experimental systems used to collect water vapour.