The human body can survive up to 3 weeks without food but only 3 days without water. Limited access to clean drinking water will be one of the results of a warming planet in many parts of the world and a prime motivation for large scale migration. Scientists in China, Germany, and the US are investigating ways of making polluted water safe for human consumption without the need of large and expensive infrastructure.
Taking A Cue From Nature
One method of decontaminating water is to add a coagulant like aluminum sulfate, which causes large particle contaminants to clump together and fall to the bottom, where they can be easily removed. But until now, such coagulants had little effect on smaller particles. As a result, further steps needed to be taken, which added complexity and cost to the purification process.
Menachem Elimelech of Yale and Huazhang Zhao of Peking University have taken a tip from nature to create a new nanocoagulant that mimics the behavior of Actinia, a sea creature in the sea anemone family. According to Science Daily, the tentacles of the Actinia retract while resting and extend to help it catch its prey. The researchers replicated the structure and the function of Actinia using organic and inorganic components.
Their nanocoagulant has a core structure that turns inside out in water. The shell destabilizes and enmeshes larger suspended particles while the exposed core captures the smaller, dissolved ones. It removes a broad spectrum of contaminants, from trace micro-pollutants to larger particles — many of which elude conventional methods and pose significant public health concerns.
“The ability to remove nitrate was quite surprising, as traditional water coagulants exhibit negligible removal of nitrate,” says Professor Elimelech. “It’s also critical to water treatment, since nitrate contamination is associated with ‘blue-baby’ syndrome, a potentially fatal condition that affects young children in some parts of the world.”
Professor Zhao adds the work holds promise for replacing current water treatment methods and greatly reducing the operating costs of water treatment because it is a one step process. “It also opens doors for fabricating ‘smart’ materials that can transform configuration and function in response to its environment,” he says. The research was published November 26 in the journal Nature Nanotechnology.
Clean Water From Sunlight
Researchers at Martin Luther University in Germany have made a clean water breakthrough of their own. They have discovered a way of removing pollutants from water that requires nothing but sunlight and a catalyst. They claim the process is so simple it can be conducted outdoors under the most basic conditions, according to Science Daily. Their research was published on September 19 in Chemistry — A European Journal.
Scientists have known for some time that highly charged electrons — known as hydrated electrons — moving freely through water are capable of degrading many dissolved pollutants. The problem is, creating those highly charged electrons usually requires a lot of energy. A research team led by Professor Martin Goez has found a way to create them using only sunlight and an anionic catalyst made from a ruthenium-metal complex.
The researchers working with Professor Goez have discovered the new process is not only a very efficient way to produce hydrated electrons but also has a wide range of applications. “Our new approach is so simple that it doesn’t even need to take place in a lab,” says Goez.
His group conducted a field trial in a meadow and tested their new approach in water contaminated with chloroacetic acid. They found the pollutants were eliminated in a small sample of water even when there was only a moderate amount of sunshine. The result has yet to be tested in large scale applications. Further testing is planned.
Once again, science has devised new and creative ways to purify water that are simple and cost effective. Either or both of these discoveries could be vital to large numbers of people who find themselves without access to clean water in coming years.
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