Defence Frederique Versteeg: "Mass transfer in supercritical CO2 and its applications"

Promotors: 1^st Promotor: Prof Francesco Picchioni, 2^nd promotor: Prof Eric Heeres, 3^rd promotor: Dr Pablo Druetta

Absract: The chemical industry must become more sustainable and less harmful to both people and the environment. Traditional production processes often rely on volatile organic compounds (VOCs), which are harmful. A green alternative is the use of supercritical fluids (SCFs), such as supercritical carbon dioxide (scCO2). ScCO2 is environmentally friendly, non-toxic, inexpensive, and can be used at relatively low temperatures and pressures. It is already applied in processes such as decaffeinating coffee.

This dissertation explores the fundamental behavior of substances in scCO2 systems, with a focus on mass transfer. Mass transfer refers to the movement of substances from one location or phase to another through diffusion and convection. The first chapters experimentally investigates how stearic acid (a solid) dissolves in scCO2 explaining this phenomenon using established mass transfer correlations (such as Sherwood, Reynolds, Schmidt). A thorough understanding of mass transfer is key to designing large-scale industrial processes.

The later chapters explore practical applications, including the removal of harmful substances from PVC, the cleaning of polymers, and improving recycled plastics. ScCO2 proves to be highly effective in these processes, achieving up to 98% impurity removal. This demonstrates that scCO2 is a green and safe alternative to traditional, more harmful solvents.

In conclusion, this research shows that scCO2 has great potential as a green solvent for sustainable technologies.

Dissertation