A novel approach to making seawater evaporate faster has been hailed as a significant breakthrough in desalination technology that will benefit billions of people worldwide.

Up to 36% of the world's eight billion people currently suffer from severe freshwater shortages for at least four months of the year, and this could potentially increase to 75% by 2050.

Seawater desalination is one of the most effective strategies to alleviate the impending scarcity, but existing processes consume massive amounts of energy, leaving a large carbon footprint.

Other problems plague the production of fresh water from the sea, including the necessity to de-scale membranes used in the reverse-osmosis desalination process with chemicals that are toxic to sea life. Furthermore, once the water is produced, the briny by-product is so overly rich in salt that it has the effect of an ecological contaminant.

Researchers from the University of South Australia (UniSA) have already demonstrated the potential of solar-powered evaporation as an energy-efficient, sustainable alternative to current desalination methods, but they are still limited by a lower evaporation rate for seawater compared to pure water due to the negative effect of salt ions on water evaporation.

UniSA materials science researcher Professor Haolan Xu has now collaborated with researchers from China on a project to develop a simple yet effective strategy to reverse this limitation.

By introducing inexpensive and common clay minerals like zeolite and bentonite into a floating photothermal hydrogel evaporator, the team achieved seawater evaporation rates that were 18.8% higher than pure water. This is a significant breakthrough since previous studies all found seawater evaporation rates were around 8% lower than pure water.