Produção e aplicação de líquidos iônicos de baixa viscosidade em processos de separação de componentes orgânicos de interesse industrial

Abstract

In this work the production and characterization of LIs with low viscosity (6.5 to 27.3 mPa.s at 25 ° C) based on cyclic amides (lactams) and carboxylic acids were evaluated, in addition physical properties were determined and the application of these in processes of separation of organic components such as aromatic, cyclic and phenol hydrocarbons was evaluated. The production of the LIs was carried out by means of neutralization reaction varying the sizes of the cations and anions chains. The chemical structures of the ionic liquids produced were confirmed by FTIR and 1 H NMR and given physical properties. LIs miscibility tests on the interest separation systems components (aromatic / aliphatic, olefin / paraffin, styrene / ethylbenzene and butanol or phenol / water) were performed to determine the formation of two phases and consequently the possibility of using LIs as solvents. It was concluded that LIs containing anions with smaller chains formed two phases with aliphatic and cyclic hydrocarbons and were therefore applied in the separation of aromatic / aliphatic and olefins / paraffins while those of larger chains were studied in the removal of phenol from water. Liquid-liquid equilibrium data were determined for heptane + toluene + LIs and cyclohexane + cyclohexene + LIs at 25 ° C by titration and densimetry techniques. The LIs presented selectivities lower than the commercial solvent sulfolane that was used as comparative in this work, however they showed selectivities greater than 1 for the systems containing heptane and toluene indicating that extraction of the toluene is possible. The ELL data were correlated by the NRTL thermodynamic model with an overall deviation of 0.63. The LIs were recovered and reused for three cycles with a mean decrease of 30% in the selectivity without significant changes in the chemical structure of the LIs. In the extraction of cyclohexene from a mixture with cyclohexane the LI with cation of lower carbonic chain showed selectivity greater than 1 only for low concentrations of solute. Thus, the possibility of application of lactam and carboxylic acid-based LIPS on the separation of olefin and paraffin is limited by the concentration of the solute. The LIs with anions of greater carbon chains evaluated in the separation of organic compounds from the water as the phenol, presented decomposition in aqueous medium making it impossible to be used as extraction solvents in aqueous systems.