Billions of people to benefit from technology breakthrough that ensures freshwater for the world

Researchers from the University of South Australia (UniSA) have demonstrated the potential of interfacial 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 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.

The key to this breakthrough lies in the ion exchange process at the air-water interface. The minerals selectively enrich magnesium and calcium ions from seawater to the evaporation surfaces, which boosts the evaporation rate of seawater. This ion exchange process occurs spontaneously during solar evaporation, making it highly convenient and cost-effective.. The researchers say the hydrogel evaporator maintained its performance even after months of immersion in seawater.