How sunlight can remove pollutants in water

Can sunlight help to purify polluted water? It can, scientists say. Water pollution and scarcity of potable water is a daunting problem that continues to dog residents in both rural and urban areas. However, a new finding by scientists from Martin Luther University Halle-Wittenberg (MLU) in Germany may provide the much-needed solution to purifying water. The scientists have developed a simple and highly effective way to remove persistent pollutants in water by using sunlight.

How the scientists rely on hydrated electrons moving freely in water to degrade dissolved pollutants

“These electrons are extremely reactive and can be used for a plethora of reactions. They break down even the most recalcitrant pollutants,” said Martin Goez, a professor at MLU, as reported by PTI.

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How the electrons work to break down pollutants

According to the scientists in a PTI report, the electrons have to be released from the molecular compounds in which they are usually tightly bound. Until now, those electrons can be generated through a complex and expensive high-power lasers. Hence, the researchers adopted a new method that needs a green light-emitting diode as the sole energy source. Vitamin C and traces of a metal complex as the catalyst were used to bring about the desired reaction. However, the catalyst had to be placed in micelles that are tiny containers. This reduced the reaction’s efficiency, and the micelle molecules themselves were only partially biodegradable.

The researchers, therefore, found the answer in a highly charged anionic catalyst based on a ruthenium-metal complex to avoid these additives. By combining this with urate (a salt of uric acid), the researchers were able to effect the desired reaction in water without the need of micelles by exploiting the Coulombic repulsions. Further investigations indicated that the new process is not only an efficient way to produce hydrated electrons but also has a wide range of applications.

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“Our new approach is so simple that it doesn’t even need to take place in a lab,” said Goez.

The trial in a meadow

The team carried out a field trial in a meadow and tested their new method in water contaminated with chloroacetic acid. They found that the pollutants were eliminated in a small sample of water even when there was only a moderate amount of sunshine.