Purify water with the power of sunlight

An international research team was able to turn brackish water and sea water into safe and clean drinking water in less than 30 minutes MOFs (organometallic frameworks) and sunlight.

In a discovery that could provide drinking water to millions of people around the world, researchers were not only able to filter harmful particles out of the water and produce 139.5 liters of clean water per kilogram of MOF per day, but also did the job in a more energy efficient way than electricity desalination.

The World Health Organization suggests that good quality drinking water should have a total dissolved solids (TDS) content of <600 parts per million (ppm). The researchers were able to achieve a TDS of <500 ppm in just 30 minutes and regenerate the MOF for reuse in four minutes under sunlight.

This first worldwide investigation was published in the renowned journal Nature Sustainability.

Lead author Professor Huanting Wang from the Department of Chemical Engineering at Monash University in Australia said that this work opens a new direction for the development of stimulus-responsive materials for desalination and water purification in an efficient and sustainable manner.

“Desalination has been used to address increasing water scarcity around the world. Because of the availability of brackish water and seawater, as well as the reliable desalination processes, treated water can be integrated into aquatic systems with minimal health risks,” said Professor Wang.

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Huanting Wang (Photo: Monash University)

“But the processes of desalination thermal evaporation are energy-intensiveand other technologies like Inverse osmosishave a number of disadvantages including high energy consumption and the use of chemicals in membrane cleaning and dechlorination.

“Sunlight is the most abundant and renewable energy source on earth. Our development of a new adsorption desalination process using sunlight for regeneration offers an energy-efficient and sustainable desalination solution from an ecological point of view”.

MOFs (Structured Metal-Organic Materials) are a class of compounds made up of metal ions that form a crystalline material with the largest known surface area. In fact, MOFs are so porous that they fit the entire surface of a soccer field with a teaspoon.

The research team created a special MOF called PSP-MIL-53. The researchers showed that the PSP-MIL-53 could produce 139.5 liters of fresh water per kilogram of MOF per day with little energy consumption. This was due to the desalination of 2,233 ppm water from a river, lake or aquifer.

Professor Wang said this underscores the durability and sustainability of using this MOF for future pure water solutions.

“This study successfully demonstrated that photoresist MOFs are a promising, energy-efficient and sustainable adsorbent for desalination,” said Professor Wang.

“Our work offers an exciting new way to develop functional materials for harnessing solar energy to reduce energy demands and improve the sustainability of water desalination.” (Source: NCYT amazement)

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