Efficient desalination of seawater is a good strategy to address freshwater scarcity, but existing processes consume a lot of energy and leave a large carbon footprint.
Up to 36% of the world’s 8 billion inhabitants currently suffer from severe freshwater scarcity for at least four months of the year, and this figure could increase to 75% by 2050, threatening human survival.
## Advances in Efficient and Sustainable Desalination
Researchers from the University of South Australia (UniSA) have demonstrated the potential of solar-powered interfacial evaporation as a sustainable alternative to current desalination methods. However, the evaporation rate of seawater is lower than that of pure water due to the effect of salt ions.
Professor Haolan Xu and his team, in collaboration with researchers from China, have developed an effective strategy to overcome this limitation, published in the journal Advanced Materials.
By introducing inexpensive clay minerals into a floating photothermal hydrogel evaporator, they achieved seawater evaporation rates 18.8% higher than those of pure water.
This represents a significant advancement since previous studies showed seawater evaporation rates approximately 8% lower than those of pure water.
## Innovative and Efficient Materials
The materials used include halloysite nanotubes, bentonite, zeolite, and montmorillonite, combined with carbon nanotubes and sodium alginate to form a photothermal hydrogel. This ion exchange process at the air-water interface selectively enriches magnesium and calcium ions from seawater on evaporation surfaces, increasing the seawater evaporation rate.
This strategy, which could be easily integrated into existing desalination systems, will provide additional access to large amounts of clean water, benefiting billions of people worldwide.
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