MME BILLARD Isabelle

I am studying the solution chemistry of metal ions in water and in innovative liquid systems, such as Ionic Liquids (ILs), Aqueous Biphasic Systems (ABS) and Deep Eutectic Solvents (DES).
- ILs are salts which melting temperature is equal or below T = 100°C. Some are hydrophobic enough to induce a meniscus when contacted with water phases, thus allowing metal extraction. Being salts, their solvating properties are totally different from those of traditional molecular organic solvents (benzene, toluene, kerosene etc.). Therefore, they can offer extraction efficiencies very different from what is possible with molecular solvents. However, they are rather expensive and their toxicity is still largely unknown.
- ABS are ternary systems composed of water plus two other compounds (ILs, polymers, inorganic salts, acids etc…). Depending on used chemical conditions (mass percentages and temperature) these mixtures can be either in a monophasic or a biphasic state, thus allowing metal extraction in a reversible way. In such systems, water is the main ingredient, thus lowering costs, but the molecular phenomena at the heart of the biphasic/monophasic changes are still poorly understood, limiting the control and use of such systems for applied studies. Interestingly, some of their constituents (polymers, salts, some ILs) are green enough to be accepted at the industrial scale.



- DES are binary mixtures with melting temperatures below what is predicted by classical thermodynamics. Some of them are also hydrophobic enough to induce a meniscus when contacted with water phases. Some of their ingredients can be bio-sourced, or rather non-toxic (and cheap) materials, rendering them an interesting approach for industrial applications. However, at the moment, their study in view of metal extraction is in its infancy.
The fundamental aim of my research work is to understand and model, if possible, the extraction mechanisms and mass transfer kinetics of metal ions from one phase to either ILs, ABS or DES. Recently, neutron scattering and other optical techniques are used (ESRF and ILL) to follow micelle formation of ILs in ABS as a function of temperature, sample composition or time. On a more classical experimental approach, analytical techniques allow to determine the composition of the upper and lower phase as a function of chemical conditions. On this basis, extraction mechanisms can be proposed, translated into mathematical equations, and fitted to the experimental results.
The applied perspective of my work is to propose, test and implement from the lab scale to the (pre)-industrial scale, innovative ways to recycle metals ions from any type of wastes, such as batteries (Ni, Co, Ln, Li etc.), PEMFC (Proton Exchange Membrane Fuel Cells) (Pt, Ni, Co etc.) or other industrial liquid or solid wastes by using innovative means such as ILs, ABS or DES. These methods should comply as much as possible with the objective of a greener world. In this frame, past projects have dealt with permanent magnets, NiMH batteries, or pickling baths, in close collaboration with industrial partners and French or European academic colleagues. In the last 6 years, three patents have been submitted on these topics.
Current applied projects (2021) concern new pickling baths, fine incineration ashes, polluted soils remediated with plants and radioactive liquid samples.