Claude Grison has demonstrated that some plants that are capable of decontaminating polluted soil can also be recycled and become valuable ingredients for science. Interview with an "eco-inspired" chemist.
"It is a virtuous circle: chemistry can become cleaner through ecology and chemistry provides economic opportunities to ecology."
It was by chance that the chemist Claude Grison became interested in ecology when students from the University of Montpellier II where she teaches consulted her on a novel question: can we repair the damage caused by man on mine sites with plants? "It was while I studied this question that I discovered that certain plant species are capable of withstanding pollution, for example on mine sites. Not only do they withstand the toxicity of soil they are capable of extracting metal elements and storing them in their leaves. This is called phytoextraction and is a 100% natural phenomenon", she explained.
Convinced that these "metal-eating” plants could play a key role in decontaminating polluted soils, Claude Grison persevered, motivated by two observations. “There is currently no green solution to clean up sites contaminated by mining operations. Furthermore, metal resources are limited and will one day run out. However, they are essential to the chemical industry which uses them as catalysts to synthesize drugs among other things.”. The scientist sensed that a virtuous circle could be set up and decided to prove that phytoextraction had an economic value in addition to its ecological potential.
She conducted her first experiments in Saint-Laurent-Le-Minier, Gard (France), and New Caledonia. This was a long process as the soil needed to be studied to identify the appropriate plants before reintroducing vegetation. "Every site is different and you have to fully respect local biodiversity. Decontamination is a slow process that can take up to fifty years on some sites. Fortunately, our work also has a short-term impact: by reintroducing vegetation, we can limit soil erosion and prevent the wind and rain from scattering metallic elements around the site with very serious health and environmental consequences.".
It took Claude Grison a whole year to meet her challenge of producing chemical catalysts from contaminated leaves collected from mine sites and a patent for this initial success was issued by the CNRS. Today, she has twelve patents. "The results went beyond our hopes" she enthused. “Catalysts obtained through phytoextraction are better than conventional catalysts because they are more active and they are recyclable which helps develop eco-friendly chemical processes that do not negatively impact the environment.”. In other words, a small green revolution is happening in the world of chemistry. "Chemistry can be clean and bio-inspired, we have reversed the trend", said Claude Grison.
Manufacturers are already taking an interest in these eco-catalysts, such as Chimex, a subsidiary of the L’Oréal Group, and the Japanese cosmetics manufacturer Takasago. "It is a virtuous circle: efforts in ecology and phytoextraction are long and costly and if the chemical manufacturers were not motivated by the economic value of these plants we would not have the funds we need to conduct this type of decontamination program. This is the principle of circular economy: chemistry provides the means for ecology to progress and the efforts of ecology help us to innovate in chemistry", said Claude Grison.
Phytoextraction could have other interesting opportunities such as the destruction of toxic pesticides or the synthesis of natural insecticides. Now head of a joint research unit (50% chemists and 50% ecologists), Claude Grison is continuing to break down the barriers of science which she believes is necessary for ecological transition. "Chemistry and ecology are not opposed. On the contrary, chemistry can become cleaner through ecology and chemistry provides economic opportunities to ecology.".
Find out more:
- Claude Grison receives the 2014 CNRS and ANR Innovation awards (French)
- Cleaning plants that gobble up heavy metals (French)
Main picture: © CNRS Photothèque / Thibaut VERGOZ