New green solvent helps trap harmful pollutants from air

Scientists in France have developed and patented an eco-friendly solvent that they claim traps harmful pollutants from air thereby cleaning it. The study describing the work of scientists is published in Springer’s journal Environmental Chemistry Letters.

We use chemicals in our day-to-day life e.g. cleaning products. It is known that harmful gaseous pollutants are released into the air when such chemicals are used and they not only cause air pollution to a certain extent, but they are also harmful for our health. That’s why there is a need to reduce the indoor and outdoor levels of these volatile organic compounds.

Many methods have already been developed to clean contaminated air, for instance, liquid mixtures that can absorb and trap volatile organic compounds are often used. Although effective, many of the current methods can be quite expensive, toxic or even unstable.

In their aim to find an improved absorbent for cleaning the air, the researchers focused their attention on deep eutectic solvents. These mixtures have recently emerged as a greener alternative to many of the liquids that are often used to absorb volatile organic compounds. Deep eutectic solvents are made by mixing two compatible components together to form a resulting liquid product at room temperature. The melting point of a deep eutectic solvent is significantly lower than that of each of its individual components.

Laboratory studies were conducted to test how well each new mixture in their liquid forms could absorb three harmful volatile chemicals. These were toluene, acetaldehyde and dichloromethane. The researchers measured their partition coefficients between the vapour and liquid phases for seven different deep eutectic solvents. A solvent based on choline chloride (an additive in chicken food) and urea was found to dissolve up to 500 times more harmful chemicals than is possible with water at 30°C.

Authors point out there are many reasons why deep eutectic solvents should be considered when it comes to cleaning air. Their absorption ability is similar or even superior to those published for ionic liquids and organic solvents of similar purpose. They say that, in general, deep eutectic solvents are easier to prepare and more biodegradable than potentially toxic ionic liquids. Such solvents are also more biodegradable than the commonly used but more expensive silicone oils. Furthermore, in terms of recycling, the absorption capacities of the tested solvents remained unchanged during five reversible absorption-desorption cycles.

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