Research Project Description

Due to the need of sustainable processes development, the list of authorized solvents is being
reduced from year to year. Among the alternative solvents for low hydrophilic substrates, pure supercritical
CO2 or its mixtures with a low proportion of ethanol appears to be an attractive candidate. One of the
advantages of processes that use this solvent lies in the easy regeneration of CO2 thanks to a
decompression step, allowing CO2 to return to its gaseous state, restoring a “clean” solute. However, this
attractive simplicity induces a high-energy consumption of the process which essentially corresponds to the
work of re-compression of CO2 for its recycling after the solute recovery.

The french ANR MemScCO2 research project (2019-2023) recently allowed to experimentally
demonstrate the feasibility of implementing a membrane separation step to recover vegetable oil
extracted by supercritical CO2, while significantly reducing energy consumption (>80%) of the process.
Membrane separation has been carried out using dense membranes based on cross-linked silicone or
polyamide polymer. An original experimental set-up was built as part of this project that can be used to test
any type of polymer membrane to assess its permeability, selectivity and stability, up to pressures of the
order of 250 bar.

In the context of this PhD thesis, it is proposed to extend the process to a wider range of CO2 +
solute mixtures, exhibiting a large range of properties in terms of solubility in CO2, volatility and
hydrophobicity, which have influence on CO2/solute/membrane interactions. The scientific purpose is to
better understand the physical phenomena that govern the process. Full advantage of the experimental
set-up and know-how acquired during the ANR project will be taken during the thesis. A methodology
should be established in order to apply this kind of low energy solvent recycling loop on existing or new
processes.

To achieve these objectives, the thesis work will focus on two complementary axes:

• Implementation of experiments after selection of CO2 + solute(s) systems of interest,
• Modeling of the transport of the solvent and the solute(s) through the membrane.
  Supervising research teams of the LGC will provide the PhD student with the necessary equipments and
  resources necessary for the successful completion of the project.
  We are looking for a PhD student interested in both membrane and supercritical processes. A young highlevel
  researcher capable of implementing concepts related to process engineering, materials, in particular
  polymeric materials, and thermodynamics is expected to be found for this multidisciplany topic. Human
  personnal qualities, dynamism and autonomy associated with a curious and thoughtful mind are also
  required.

We are looking for a PhD student interested in both membrane and supercritical processes. A young highlevel
researcher capable of implementing concepts related to process engineering, materials, in particular
polymeric materials, and thermodynamics is expected to be found for this multidisciplany topic. Human
personnal qualities, dynamism and autonomy associated with a curious and thoughtful mind are also
required.

Contact of PhD Supervisors :

Camy Séverine
Toulouse Institut National Polytechnique – ENSIACET
Severine.camy@ensiacet.fr

Remigy Jean-Christophe
Université Paul Sabatier
jean-christophe.remigy@univ-tlse3.fr