Thesis subject
BSc & MSc - Ionic liquids for smart separations
Ionic liquids (ILs) enjoy increasing attention as it is a new class of (green) solvents with many unique properties. Being salts, they are composed of positively and negatively charged ions. At room temperature they are in the liquid state, because the charged groups are attached to (low molar weight) hydrophobic moieties. ILs have a solubility gap with many liquids, including both water and oil, and therefore can be used to extract components from such solutions. In a team consisting of three research groups you will work on the use of ILs for smart separation purposes, e.g. to extract surfactants from oil/water emulsions or extract valuable proteins (e.g. biopharmaceutical proteins) from a complex feed stream mixture.
For a mild but efficient extraction, small drops are desired. That is why our focus is on the making of IL-in-water emulsions. You will study the stability of such emulsions, e.g., as a function of temperature, to help other team members to design process engineering routes for IL-emulsions. For example, there exists ILs that are magnetoresponsive. We are planning to use this property to help to concentrate the IL-emulsion while recovering/regenerating the ILs.
In one of the key research lines at PCC complex coacervate core micelles (C3M) are being studied which results from copolymer self-assembly. In this case the complexation of oppositely charged polyelectrolytes drives the self-assembly resulting in a polymer-rich core. This is combined with a classical stopping mechanism, that is, uncharged polymer moieties accumulate in a corona brush that surrounds the complex coacervate core. In contrast to the classical surfactant systems where hydrophobic interactions are the reason for self-assembly, the C3M's are more adaptive, as they can respond to pH and ionic strength. We are planning to use the knowledge about polyelectrolyte block copolymers to find a reasonable emulsifier for ionic liquids.
At present we are in the process of starting up a PhD project on this topic. Our first target in this project is to make emulsions of ILs in water. Both Bsc and Msc students who are keen on doing explorative work are welcomed. They may become involved in (i) the search of such emulsions. (ii) They may also work on various techniques of how the size and stability of these emulsions can be manipulated. It may also be important to know (iii) the phase behavior of ILs in the presence of oil or water. In the latter case the ionic strength and the type of ions in the water phase are important parameters.
As mentioned briefly already, one of the applications we have in mind is a problem that occurs in tertiary oil recovery. In an attempt to squeeze out more oil from a reservoir, one nowadays considers to pump surfactants down in a well. The oil emulsifies and a complex mixture of oil-water-surfactant is recovered. Of course the oil company is only interested in the oil and is keen to separate the water from the oil. It would also be beneficial if the surfactant could be recovered. Breaking emulsions is not an easy task. Surfactants at the oil water interface are not easily removed. In the case of ionic surfactants, we are keen to strip the surfactants from the oil-water interface by confronting an oil-in-water emulsion with a IL-in-water emulsion. The partitioning of ionic surfactants from the oil-water interface into the IL (and replacing a co-ion from the IL, or incorporating a counter-ion) effects in the coarsening of the oil-water emulsion.
Experimental techniques:
- Methods to make emulsions (Ultratorax, micro-fluid devices)
- Methods to determine the size and stability of emulsions (light scattering, microscopy)
- Methods to study emulsifiers (Langmuir tough, Whilhelmy plate tensiometers)