Technology that can turn salty seawater into brackish water into safe, clean drinking water has the potential to transform millions of lives around the world, which is why so many scientists are working on projects to do just that.
Now, a new innovation developed by scientists in Australia could be the most promising, yet, with researchers using metal-organic framework compounds (or MOFs) along with sunlight to purify water in just half an hour, with a process that is more efficient is then existing techniques.
It’s cheap, it’s stable, it’s recyclable, and it’s producing water that meets the World Health Organization (WHO) standards for desalination. About 139.5 liters (nearly 37 gallons) of clean water can be produced per day from one kilogram (2.2 pounds) of MOF material, based on early testing.
After only four minutes of exposure to sunlight, the material releases all the salt ions, which it is awakened by the water, and is ready to use again. The team behind the new process says it is delivering several upgrades over existing desalination methods.
“Thermal desalination processes by evaporation are energy intensive, and other technologies, such as reverse osmosis, have a number of disadvantages, including high energy consumption and chemical use in membrane cleaning and dechlorination,” says chemical engineer Huanting Wang of Monash University.
“Sunlight is the most abundant and sustainable source of energy on Earth. Our development of a new adsorbent-based desalination process using sunlight for regeneration provides an energy-efficient and environmentally sustainable solution for desalination.”
The researchers created a new MOF called PSP-MIL-53, which consisted in part of a material called MIL-53, already known for the way it reacts to water and carbon dioxide.
Although this is not the first piece of research that suggests the idea of using an MOF membrane to purify the salt from seawater and brackish water, these findings and the PSP-MIL-53 material behind their scientists will provide many more options. to explore.
MOFs in general are highly porous materials – just a teaspoon of the material when compressed can be opened to cover an area the size of a football field – and this new system could potentially fit on pipe and other water systems to provide clean drinking water to produce.
“Desalination has been used to address the escalating water shortage worldwide,” Wang says. “Because of the availability of brackish water and seawater, and because desalination process is reliable, treated water can be integrated into existing aquatic systems with minimal health risks.”
New solutions cannot come fast enough – according to WHO, around 785 million people worldwide lack a clean source of drinking water within a half hour walk of where they live. If the climate crisis takes hold, that problem will be lessened.
With salt water accounting for up to 97 percent of the planet’s water, this is a major untapped source for lifelong drinking water, as solutions such as PSP-MIL-53 can be found to make it suitable and safe for human consumption.
It’s not clear how close researchers are to getting their system into a working, practical form, but it’s encouraging to see a different approach tested – along with those using ultraviolet light, graphene filters, and sunshine and hydrogels . Scientists are even considering methods to extract water from thin air.
“Our work provides an exciting new route for the design of functional materials for the use of solar energy to reduce energy demand and improve the sustainability of water desalination,” says Wang.
“These sunlight-responsive MOFs could potentially be further functionalized for low-energy and environmentally friendly means of extracting minerals for sustainable mining and other related applications.”
The study was published in Nature Sustainability.
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