Clean drinking water is one of the essentials of life. However, safe drinking water is not a reality for more than 2 billion people worldwide. These people are at risk of potentially fatal waterborne diseases such as typhoid and polio.
According to the World Health Organization (WHO), this population at risk will increase over the next five years as the climate crisis creates more and more areas of water stress, according to the World Health Organization. (WHO).
Scientists have been trying to solve this problem for decades, and while some of the solutions have been successful at effectively purifying water, these energy-intensive solutions can be difficult to implement at home. communities that do not have stable power grids.
Now, a group of scientists from Australia and China have proposed a sustainable solution that relies on sunlight to initiate the filtration process instead of heat or electricity.
Using a super porous material to absorb salt from brackish, salty water, researchers were able to create almost sustainably 40 gallons of clean drinking waterr per kg of metallic material. Better yet, this drinking water is even cleaner than the official WHO guidelines.
This finding was published on Monday in the journal Sustainability.
“Sunlight is the most abundant and renewable source of energy on Earth.”;
Study lead author Huanting Wang, professor of chemical engineering at Monash University in Australia, says his team’s approach uses the planet’s most abundant resource: sunlight. Their solar method of desalination of brackish water, or stagnant water, is more sustainable than previous methods.
“[T]The evaporative hermal desalination process consumes a lot of energy and other technologies, such as reverse osmosis, have a number of limitations, including high energy consumption and chemical use, Wang said. membrane cleaning and chlorination. “energy source on Earth.”
Wang and his colleagues explain in the study that a sustainable energy source, such as sunlight, will be especially useful for communities that may not have access to the reliable power grids needed for other desalination methods.
How it works – While sunlight is a vital part of this process, another important factor is the material the researchers have chosen to use. This material is a type of metal compound consisting of metal ions that are configured in the form of crystals – unlike the salt it is intended to absorb.
Due to its unique crystal structure, this compound is extremely porous, with so many niches and crevices within it that its overall surface area is actually the largest per unit of measure. any known material.
In fact, so big that the scientists estimate the entire area of a soccer field can fit in a teaspoon of this material. A property that makes it really effective at drawing salt out of water.
Researchers have further enhanced the absorption of this material by adding other material for its voids, is known as PSP-MIL-53. This material is characterized by having a “breathing effect” and is able to promote effective absorption.
After testing the material on both natural and synthetic saltwater, they found that the compound was able to absorb enough water for 30 minutes to produce nearly 40 gallons of fresh water per kilogram of material.
When analyzing water results, the researchers measured its total dissolved solids (TDS) to be below 500 parts per million – a standard even higher than the WHO recommendation, classifying clean drinking water as having TDS. greater than 600 parts per million.
The initial absorption is done in the dark, but a four-minute exposure to sunlight causes the material to release the resulting salt and resumes absorption for many more cycles.
“This study has successfully demonstrated that optical response [metal compounds] “Our work offers an exciting new roadmap for the design of solar-powered functional materials to reduce energy demand and improve the sustainability of desalination,” says Wang. domestic”.
What’s Next – In addition to helping provide a sustainable solution to creating clean drinking water for communities with poor energy infrastructure, the researchers also say that this approach can be reused in the future to Absorb other compounds and minerals, creating a sustainable solution for mining as well. What has to happen next is determining how to get this technology out of the lab and into the field.
Abstract: Light-reactive materials with high adsorption and regeneration capacity activated by sunlight are desirable for low-cost, environmentally friendly and environmentally friendly separating processes. Here, we report a functional metal-organic framework poly (spiropyran acrylate) (PSP) (MOF) as a solar light renewable ion adsorbent for sustainable water desalination. In the dark, the zwitterionic isomer rapidly absorbs many cations and anions from water within 30 minutes, with a high ion adsorption load of up to 2.88 mmol g-1 NaCl. With sunlight illumination, the neutral isomer rapidly releases these adsorbed salts within 4 minutes. One column desalination experiments have demonstrated that PSP-MOF works effectively to desalinate water. Fresh water yield of 139.5 l kg – 1 d – 1 and low energy consumption of 0.11 Wh l – 1 would be achieved for the desalination of synthetic brackish water 2,233 ppm. Importantly, this adsorbent shows excellent cycle stability and performance. This work opens a new dimension to the design of materials that respond to stimuli for efficient and sustainable desalination and water filtration.