Advances have been made in technology for harvesting water from the atmosphere, as researchers have demonstrated collection systems that require external energy sources or complex desorption steps. A more streamlined approach devised by researchers from the National University of Singapore and University of Toronto relies on an aerogel to sponge water from the air without power or process inputs.

A chromium terephthalate metal-organic framework (MOF) was combined with a poly(N-isopropylacrylamide) Schematic of the autonomous airborne water supplier shows the hydro-active sites on polymer chains that capture atmospheric moisture. Source: G. Yilmaz et al.matrix to merge the superior water sorption properties of the former with the dynamic conformational water repelling feature of the latter. The aerogel-like material enables continuous sorption-desorption, autonomous water release and stand-alone airborne water supply without moving parts and at minimum external energy expenditure without the use of evaporators or condensers.

The polymer-MOF matrix demonstrated continuous water delivery for 1,440 hours and produced 6 g of fresh water per gram of sorbent at 90% relative humidity per day without active condensation. This leads to a total liquid delivery efficiency of 95% and an autonomous liquid delivery efficiency of 71% for the stand-alone system, surpassing the production of other atmospheric water harvesters tested to date.

The research is reported in Science Advances.