Surface reactivity of nanomaterials

Our research group has skills and equipment that allow probing interactions between mineral surfaces and fluids over a wide range of conditions ranging from atmospheric pressure and low temperature to intermediate hydrothermal conditions with a control on (or a – often in situ – measure of) redox, ionic activity, pH, … In addition, our group has developed over the years the ability to synthesize a variety of reference minerals whose surface properties (chemical composition, crystal size, specific surface area, density of defects, etc…) can be controlled. This experimental ability is complemented by our expertise in solid-state chemistry methods to probe the structure of minerals involved, even if highly defective, its evolution, and the speciation of interacting elements and molecules. The combination of both experimental expertises allow unraveling reaction mechanisms operating at mineral surfaces. This ability is enhanced by computational approaches of atomistic and molecular modeling, often performed in collaboration, whereas thermodynamic modelling extends the application domain of the results and helps determining factors (un)favorable to the studied reactions and quantifying their influence.
Within this general scope, fined-grained, and possibly layered and/or defective, minerals and their synthetic analogues (nano-materials) are of special interest owing to their high reactivity, whereas reactions occurring in natural environments represent a major source of inspiration, with two main domains of application:

– Interactions between mineral surfaces and contaminants in the perspective of remediation: Both organic molecules and inorganic elements are targeted. For the former, sequestration of complex organic molecules at the surface of clay minerals and oxidizing degradation of organic contaminants at the surface of Mn and/or Fe oxides are typical case studies, the latter in collaboration with the HyMag’in start-up. On the other hand, the long-term study of interactions between Mn oxides and trace metal elements (transition metals and rare-earth elements) will be continued in the framework of collaborative projects, in particular with Chinese partners. Special attention will be paid to the fate of these elements during mineral transformations affecting Mn oxides in natural environments.

– Interactions between mineral surfaces, elements and molecules in a GeoRessources perspective: Interactions with organic molecules will address both gas sequestration (H2, CH4) and energetic molecule production (CH4, small organic molecules, light hydrocarbons) at mineral surfaces. On the other hand, interactions with elements will focus mainly on critical metal mineralization processes, especially in the alpine context, and on the partition of dilute elements between mineral phases.
In these diverse contexts, a detailed understanding of reaction mechanisms involved will allow modeling the processes and optimizing the conditions and materials to enhance the effect of interest. Thermodynamic modelling of these processes will allow extending the relevance of experimental results to domains that are not (or hardly) accessible experimentally.

Contacts:
– B. Lanson
– A-L. Auzende
– F. Brunet
– L. Truche
– B. Malvoisin
– E. Janots
– S. Jelavic