Development of new Potassium-ion cells with high performances and low environmental impact
Lithium ion batteries are considered as the reference system in terms of energy density and cycle life and will play a key role in the energetic transition, especially concerning electric vehicles. However, such a technology involves the use of a large amount of critical elements and active materials are synthesised using energy intensive processes.
In this way, our team is developing a new Potassium-ion batteries technology with high performances but with a low environmental impact.
For this innovative and ambitious project, CEA-LITEN (one of the most important research institute in Europe) is looking for a talented post-doctoral researcher in material chemistry. The post-doctoral position is opened for a young researcher with a high scientific level, interested by valorising her/his results through different patents and/or scientific publications.
Plastic recycling enabled by toxic additives extraction using green solvents
It is important to develop the scientific knowledge and stimulate innovations to recycling Plastics. The extremely large variety of plastic based objects that we use in our daily life are made of a wide range of plastic materials covering many different polymers, many different formulations. Plastics objects are also used for many purposes and there is therefore the need of various ways to collect, sort and treat them.
Methods of recycling of plastics are generally divided into four categories: primary, secondary, tertiary, and qua-ternary (see Figure 9). Primary recycling or closed loop recycling method is considered when the materials after recycling present equal or improved properties compared to the initial or virgin materials. When the recyclates present a decrease in the properties level, one may spook about secondary or down-cycling method. In tertiary (also known as chemical or feedstock) recycling method, the waste stream is converted into monomers or chemicals that could be advantageously used in the chemical industries. Finally, quaternary (also known as thermal recycling, energy recovery, and energy from waste) recycling method corresponds to the recovery of plastics as energy and is not considered as recycling for Circular Economy.
Various processes can be considered for chemical recycling which present different level of maturity. Hence this project that will study the decontamination of various PVC formulations using green solvents, and more particularly supercritical CO2
This work located in Saclay, France, in the heart of the University Paris-Saclay and will benefit from a very multidisciplinary and international environment.
This work will benefit from the prestigious framework of the France 2030 funding, and more precisely the PEPR Recycling (https://www.cnrs.fr/fr/pepr/pepr-recyclabilite-recyclage-et-reincorporation-des-materiaux-recycles ). It will be supervised by Dr. Jean-Christophe P. Gabriel: linkedin.com/in/jcpgabriel).
Hybrid ion exchangers for the traetment of radioactive organic liquids: molecular dynamics design assistance
The ECCLOR project (labelled 'Investissement pour le future') focuses on the treatment of radioactive organic effluents by developing porous materials capable of selectively eliminating alpha emitting ions. Research carried out at CEA has led to the design of hybrid materials with variable performance in capturing alpha emitters present in organic liquids. Understanding this performance at the molecular level is essential, but complex.
To address this challenge, this post-doctoral fellowship focuses on the use of classical molecular dynamics to rationalize these performances. The work will be carried out at the Marcoule research center's LILA laboratory, drawing on the expertise of teams specializing in the modeling of solid/liquid systems using classical molecular dynamics.
To support these simulations, experimental data may be provided by laboratories such as the Laboratoire des Procédés Supercritiques et de Décontamination (LPSD) and the Laboratoire de Formulation et Caractérisation des Matériaux minéraux (LFCM). The results obtained will be discussed at progress meetings and will be the subject of scientific publications.
In summary, this post-doctoral contract aims to couple theoretical approaches with experiment. Understanding the interactions within these materials at the molecular scale is essential to provide insights and improve the processes currently under study.
Design of new microfluidic tools for liquid-liquid extraction chemical processes
This 12-month post-doc proposal is part of the PIA MiRAGe: Future Investment Plan “Microfluidic Tools for Accelerated R&D on Recycling Processes”.
The MIRAGE project aims to provide a set of micro and millifluidic tools, platforms and methods to accelerate, intensify and make more flexible R&D on new recycling processes for strategic metals, nuclear or non-nuclear, while minimizing quantities of materials used.
To do this, new microfluidic tools have been designed at CEA ISEC to perform counter-current liquid-liquid extraction operations. These tools make it possible to redefine the orders of magnitude in the importance of the physico-chemical phenomena involved.
The interest of this invention is twofold and will be the core work of this post-doc:
- Carry out extraction operations over very low times and liquid volumes.
- Transpose this invention to larger volumes.
Thus, initially this post-doc work will seek to study in more detail the capabilities of this new microfluidic device, then to transpose this new technique to larger contactors.
The work will be carried out in the ISEC facilities at the CEA, on the Marcoule site in partnership with the CNRS, Universities and the INP of Toulouse.
Experimental and technological developments of a process for the mineralization of organic liquid waste by plasma
The ELIPSE process developed at the CEA allows the destruction of organic liquids by injection into a high-power plasma.
If the feasibility of destroying different organic components at flow rates of a few liters per hour has now been demonstrated, tests must now be further developed for reference organic liquids appropriately chosen according to existing deposits.
These studies, based on the characterization data of the chosen LORs, will aim to provide detailed process results obtained with the most representative operating conditions, to allow a complete and quantitative evaluation of the process. This will make it possible to establish operating, robustness and endurance data for the process.
This work will include the study of the behavior of radioelements in the process, which will be essential for the nuclearization study: this will involve studying the physico-chemical behavior of actinides during their processing via the use of inactive simulants.
Thermodynamic investigation of Metal-Insulator-Transition materials – The case of doped VO2 for smart windows applications
The present post-doc proposal aims to develop a specific thermodynamic database on the V-O-TM (TM=Fe,Cr) system by using the CALPHAD approach. The candidate will conduct experimental campaigns to obtain relevant data to feed the thermodynamic models. The candidate will mostly use the experimental equipment available at the lab (DTA, annealing furnaces, high temperature mass spectrometry, laser heating, SEM-EDS). In addition, the post-doc may participate to combinatorial high-throughput activities led by other laboratory of the Hiway-2-Mat consortium (e.g., ICMCB in Bordeaux), allowing a better connection between the CALPHAD simulation output and the accelerated characterization platform. The thermodynamic database will be then included in the autonomous research routine implemented in the material exploration path.
Uranium and plutonium oxide synthesis by Advanced Denitration in presence of Organic Additives
The preparation of (U,Pu)O2 MOx fuel (Mixed oxide fuel), is based on the formation of actinide oxide species from purified uranium and plutonium aqueous solutions and constitutes one of the key steps for spent nuclear fuel recycling. More specifically, the formation of actinide oxide solid solutions is a pivotal point for the multi-recycling process with FNR (Fast Neutron reactors). In this framework, the ADOA process (Advanced Denitration in presence of Organic Additives) represents a potential pathway to prepare actinide oxides without the usual valence adjustment step and enables to prepare mixed oxides thanks to a very good cationic homogeneity. This process is based on the formation of a polymeric gel, which allows homogeneous immobilization of the cations, which is then dehydrated and calcinated, ultimately leading to the synthesis of an actinide mixed-oxide. However, an optimization of the physico-chemical parameters is still needed for this process to meet the industrial MOx fuel fabrication requirements.
The aim of this postdoctoral research project will be to determine the optimal experimental conditions for the polymerisation, dehydration and calcination steps and evaluate the process robustness. The impact of these conditions on the actinide oxide morphology and its impurity content (especially residual carbon content), ease of process implementation and its adequacy with the requirements for the MOx fuel fabrication process will also be investigated.
The candidate must have a PhD in radiochemistry or solid state chemistry. Since the main part of this study will be based on glovebox experiments with the study of radioactive ceramic materials, skills on glovebox handling and materials characterization will be an asset to get this position. The results obtained during this study will be featured in patents and/or scientific publications, opening job possibilities in academic or industrial research and development sectors.
Synthesis and structural analysis of reference uranium minerals for the identification of uranium-bearing phases in mining environment by TRLFS.
In the frame of the collaborative project between the ICSM , CEA and Orano, a study is conducted in order to detect and identify minerals containing uranium (VI) by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS). This technique showed its efficiency in order to identify the presence of uranyl in natural assemblies through the probing of the local environment of uranium. However, it requires the establishment of a database from synthetic and natural samples fully characterized. Therefore, in order to achieve this goal, we intend to synthesis, and thoroughly characterize a variety of compounds containing uranyl groups within the crystal structure. We can cite the families of oxi-hydroxide, sulfate, and silicates based compounds. Then, TRLFS spectra will be collected in order to complete the database and to evidence the impact of the local structure of uranyl cation on the intensity and the position of the emission bands. The obtained data will be also compared to a collection of natural samples.
Modelling of uranium precipitation kinetics as a function of pH. Application to fluidized bed reactor
The Orano plant in Niger (Somaïr) precipitates its uranium concentrate in a fluidized bed reactor by adding sodium hydroxide. The concentrate obtained contains around 6% sodium which leads to converter penalties. Orano carried out tests at the end of 2019 on a fluidized bed in the laboratory to change the operating point of precipitation and preferentially form UO3 via a change in pH. To refine the management of the industrial unit, it is necessary to model the precipitation reactions of uranium. The candidate will have to propose and calibrate a competitive precipitation model for Na2U2O7 and UO3 based on the equilibrium constants and reaction kinetics, as a function of the pH within the reactor. In particular, the model should make it possible to understand the impact of pH on the distribution of the two main species identified in the concentrate: Na2U2O7 and UO3. This chemical model should serve as input to an existing physical model of the fluidized bed reactor. An extension of the model to other precipitation reagents, in particular magnesia, could also be studied.