New technology uses sunlight to turn salty water safe to drink in 30 minutes

Representational image

New Delhi (NVI): A new technology that can convert salty seawater water into clean drinking water in less than 30 minutes, has the potential to transform millions of lives across the globe, according to a new study.

In a study led by Monash University, researchers based in Australia used a metal-organic framework compound (MOF), a type of lattice-like crystal, together with sunlight to purify water in just half an hour, a process that’s more efficient than existing techniques.

The study has used a compound which is cheap, it’s stable, it’s reusable, and it produces water that meets the World Health Organisation (WHO) standards for desalination.

Around 139.5 litres (nearly 37 gallons) of clean water can be produced per day from a kilogram (2.2 pounds) of MOF material, based on early testing.

Moreover, in just four minutes of exposure to sunlight, the material releases all of the salt ions it’s soaked up from the water, and is ready to be used again. The team behind the new process said that it provides several upgrades over existing desalination methods.

Huanting Wang, chemical engineer from Monash University, said, “Thermal desalination processes by evaporation are energy-intensive, and other technologies, such as reverse osmosis, have a number of drawbacks, including high energy consumption and chemical usage in membrane cleaning and dechlorination.”

“Sunlight is the most abundant and renewable source of energy on Earth. Our development of a new absorbent-based desalination process through the use of sunlight for regeneration provides an energy-efficient and environmentally-sustainable solution for desalination,” he added.

The researchers created a new MOF called PSP-MIL-53, which was partly made up from a material called MIL-53, already known for the way it reacts to water and carbon dioxide.

It’s the first piece of research to propose the idea of using a MOF membrane to clean the salt out of seawater, these findings and the PSP-MIL-53 material behind them will give scientists plenty more options to explore, as per the study.

MOFs in general are very porous materials – just a teaspoon of the material when compressed can be opened out to cover an area the size of a football field – and this new system could potentially be fitted to pipes and other water systems to produce clean drinking water.

According to WHO, globally around 785 million people lack a clean source of drinking water within half an hour’s walk of where they live. As the climate crisis takes hold, that problem is getting worse.

With saline water making up around 97 per cent of the water on the planet, that’s a vast untapped resource for life-giving drinking water, if solutions such as PSP-MIL-53 can be found to make it safe for human use, it added.

However, it’s not clear how close the researchers are to getting their system into a working, practical form, but it’s encouraging to see another approach being tested – along with ones using ultraviolet light, graphene filters, and sunshine.

“Our work provides an exciting new route for the design of functional materials for using solar energy to reduce the energy demand and improve the sustainability of water desalination,” said Wang.

“These sunlight-responsive MOFs can potentially be further functionalised for low-energy and environmentally-friendly means of extracting minerals for sustainable mining and other related applications,” he added.