Yeah, I saw the condensation in the column, but since that's where the salt water comes in I figured it would be related to that. The article talks about "steam that builds up on the disc", which I understood to mean its upper surface.
The university's press release at https://www.monash.edu/news/articles/water-solutions-without... says: "Researchers created a disc using super-hydrophilic filter paper with a layer of carbon nanotubes for light absorption. A cotton thread, with a 1mm diameter, acted as the water transport channel, pumping saline water to the evaporation disc. The saline water is carried up by the cotton thread from the bulk solution to the centre of the evaporation disc. The filter paper traps the pure water and pushes the remaining salt to the edges of the disc."
My best guess at what this means is that some of the water is turned into vapor (not really steam at 100 C, I guess?) and that this evaporation drives the capillary effect that keeps bringing in new water. Some other part of the water, the part that "the filter paper traps", could then drip out into the column. Maybe? Or maybe this prototype is really more about just demonstrating that salt can be collected, and doesn't care about capturing the water.
