Research Unit of Environmental and Chemical Engineering, University of Oulu, Finland
Research Unit of Sustainable Chemistry, University of Oulu, Finland
Optoelectronics and Measurement Techniques Laboratory, University of Oulu, Finland
Research Unit of Fiber and Particle Engineering, University of Oulu, Finland
In this paper, the dehydration and purification of a deep eutectic solvent choline chloride-urea (ChCl-urea) by pervaporation is presented. The stability of polymeric pervaporation membranes was first studied by exposing the membranes to ChCl-urea for 5 days at 40 °C and 60 °C. The results showed that the membranes were stable when in contact with ChCl-urea and no membrane material was dissolved. In the dehydration experiments, the permeate fluxes were highest with the polydimethylsiloxane (PDMS) membrane: 267.65 g m-2 h-1 at 50 °C and 413.39 g m-2 h-1 at 60 °C. Raman spectroscopy was employed in the analysis of the samples. The results also showed the decomposition of ChCl-urea, and the presence of the decomposition products, i.e., ammonia and carbamate, in the PDMS and PDMS-PVA-TiO2 permeates. With the highest permeate fluxes and simultaneous removal of water and decomposition products, PDMS appeared to be the most promising membrane for the purification and dehydration of ChCl-urea.