French researchers have patented an eco-friendly and less expensive liquid mixture that could trap harmful pollutants from the air.
The non-flammable solvent contains urea and choline salt, two common ingredients in chicken feed, said Leia Morua of the Unité de Chimie Environnementale et Interactions sur le Vivant in France and lead author of a recent study.
The researchers set out to improve absorbents for cleaning the air, focusing their attention on deep eutectic solvents. These mixtures have recently emerged as a greener alternative to the liquids that are often used to absorb volatile organic compounds. They are made by mixing two compatible components together to form a liquid product at room temperature. The melting point of a deep eutectic solvent is significantly lower than that of the individual components.
Harmful gaseous pollutants in the form of volatile organic compounds are often released into the air when chemicals are used, like in cleaning products. It is important to reduce the indoor and outdoor levels of the volatile organic compounds for humans as well as the environment. One common method is using a liquid mixture that can absorb and trap the volatile organic compound. Although effective, this method can be expensive, toxic and sometimes unstable.
Laboratory studies were conducted to test how well each new mixture in their liquid forms could absorb three harmful volatile chemicals. The harmful chemicals were toluene, acetaldehyde and dichloromethane. The researchers measured the partition coefficients between the vapor and liquid phases for seven different deep eutectic solvents. A solvent based on choline chloride and urea dissolves up to 500 times more harmful chemicals than is possible with water at 30˚C.
There are many reasons why deep eutectic solvents should be considered for cleaning the air. Their absorption ability is similar or even superior to those published for ionic liquids. These solvents are more biodegradable than commonly used and more expensive silicone oils. The absorption capacities of the tested solvents remained unchanged during five reversible absorption-desorption cycles.
"They are cheap to produce, are often made of naturally occurring chemicals, are recyclable, non-flammable and mostly biodegradable," said Moura. "Consequently, these solvents could be an ecological alternative to the conventional absorbents."
A study on these findings was published in Environmental Chemistry Letters.