Abstract
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