🫧 A membrane to efficiently and sustainably clean the air

Among the most concerning air pollutants are volatile organic compounds (VOCs), toxic substances capable of diffusing into the outdoor atmosphere as well as confined environments.

Each year in France, air pollution is responsible for several tens of thousands of deaths. Among the most polluting compounds, volatile organic compounds (VOCs) are molecules such as hydrocarbons, alcohols, aldehydes..., which volatilize very easily and end up in the atmosphere. Due to their toxicity and persistence in the environment, it is therefore crucial to limit their emission or optimize their destruction.


Conventional VOC elimination methods - thermal oxidation, adsorption or condensation - have significant limitations in terms of efficiency, cost or environmental impact. A promising alternative is to use enzymes, these biological catalysts capable of specifically transforming certain pollutants.

However, their implementation faces a major challenge: many VOCs are hydrophobic, meaning they dissolve poorly in water, the medium in which enzymes are active and which they need to survive. It then becomes difficult to effectively make pollutants and enzymes interact, unless one succeeds in bridging these two worlds.

This is what scientists from the Institute of Chemical Sciences of Rennes (CNRS/University of Rennes/ENSCR/INSA Rennes) have just achieved, in collaboration with international partners (Khalifa University, United Arab Emirates). The first step, perfectly mastered, consists of transferring VOCs from the air into a liquid organic phase for which they have an affinity.

The scientists then developed an original membrane (Janus) that will serve as an interface between the two immiscible media: a hydrophobic face, the organic phase containing the pollutants to be eliminated, and enzymes grafted onto the hydrophilic face, capable of eliminating them (Figure). This device thus allows the VOCs present in the organic phase and the enzymes to come into contact, without having to mix the two phases.


Tested on phenol, a common model pollutant, this enzymatic membrane system eliminates up to 74% of it in ten hours. Another advantage: the enzymes immobilized on the membrane can be reused over several cycles, which significantly improves the durability of the process. The scientists also showed that the membrane structure promotes the transfer of pollutants between the two phases while maintaining their separation, an essential condition to ensure the device's efficiency.

This study shows the potential of Janus membranes as enzymatic reactors for the treatment of hydrophobic VOCs. By combining pollutant capture and degradation within the same device, this approach paves the way for more compact, selective and environmentally friendly processes.

Editor: Christophe CARTIER DIT MOULIN