Reactions and Separations in Green Solvents

Most chemical processes involve solvents in the reaction and the separation step. These solvents give rise to a heavy environmental and economical burden. Moreover, these solvents are based on non-sustainable resources like petroleum. The aim of this thesis has been to develop a number of alternative processes based upon green (sustainable) solvents, and to demonstrate that these processes can be economically and ecologically advantageous. The green solvents investigated were water (polar, protic), supercritical carbon dioxide (apolar, aprotic) and ionic liquids. Water was used for the recovery of soda and molybdate by eutectic freeze crystallization from an industrial waste stream, leading to a zero waste discharge process. Supercritical carbon dioxide was shown to be an excellent solvent for the extraction of natural products like cannabis, for the foaming of polystyrene and for the dyeing of cotton. In a number of reactions ionic liquids were good replacements for traditional solvents. The first generation ionic liquids are based upon petroleum chemicals. In this thesis ionic liquids based upon natural products were synthesized and successfully applied. Based upon these results it can be concluded that the replacement of oil based solvents by green solvents is only a question of time.Process and EnergyMechanical, Maritime and Materials Engineerin