A growing societal need

This knowledge is important because it makes it possible to meet the growing demand on the part of industry for products that are more natural and less linked to the petrochemical sector. Manufacturers of roof coverings, for example, are more and more inclined to use additives which are not of a petrochemical nature but instead choose plant-based products. Producers of plastic bottles also try to perfect polymers which, at least in part, are of plant origin rather than being by-products of petroleum (polyethylene terephthalate type products, PET). Whether this choice is motivated by marketing strategy or a genuine concern for the scarcity of petrol (and its expensiveness), this type of demand is the core of the research being carried out by the Industrial Biological Chemistry Unit.

In addition to being confronted by a major obstacle, the pretreatments applied to lignocellulosic matter, in addition to the intrinsic composition of these can also have an effect on the lignin that is extracted. And this can, in turn, have an effect on the quality of “ecological” products demanded by the market. This is the reason the researchers have recently studied the lignin from Miscanthus (Miscanthus x giganteus) and Switchgrass (Panicum Virgatum), two “model” plants grown in Europe and the United States respectively, well-known for being easy to grow and for their high productivity and which have already been used as raw materials for bioethanol.

Following research spread over two years (1), the researchers succeeded in establishing a significant correlation between the pretreatment applied to these plants and the antioxidant property of the lignin that is extracted from them. “This antioxidant property struck us as interesting because it can act as a factor of stability for future bio-sourced products”, comments Aurore Richel. “We have essentially studied biochemical treatments (chemical and enzymatic hydrolysis, treatment with water vapor, etc.). We discovered that acidic treatments are most favorable for the antioxidant properties of lignin. Conversely, conditioning during the basic phase has much less influence on these properties. By carefully choosing the type of treatment used for extracting the lignin, we can greatly strengthen one or other physical property required for the product concerned for example, resistance to ultraviolet radiation. This can enable us to slow down the yellow staining or ageing of certain finished products”.

(1) “Can Lignin Wastes Originating From Cellulosic Ethanol Biorefineries Act as Radical Scavenging Agents?” Vanderghem, Jacquet, Richel, Aust. J. Chem. (2014), sous presses  http://hdl.handle.net/2268/164439
“Optimization of a formic/acetic acid delignification treatment on beech wood and its influence on the structural characteristics of the extracted lignins” Simon, Brostaux, Vanderghem, Jourez, Paquot, Richel, J. Chem. Technol. Biotechnology. (2014), 89(1), 128-136. http://hdl.handle.net/2268/149591
“Lignin extraction from Mediterranean agro-wastes: Impact of pretreatment conditions on lignin chemical structure and thermal degradation behavior” Manara, Zabaniotou, Vanderghem, Richel, Catal. Today. (2014), 223, 25-34 .http://hdl.handle.net/2268/159215