Experimental investigations on the regeneration of desulfurized 1-butyl-3-methylimidazolium tetrachloroferrate [Bmim][FeCl4] and 1-butyl-3-methylimidazolium thiocyanate [Bmim][SCN] ionic liquids: A raman spectroscopic study

The room temperature and task-specific ionic liquids nowadays have been investigated widely for the removal of sulfur compounds from the natural gas streams. However, the major challenge is the recovery of the desulfurized ionic liquids, which need some significant developments. In this study, two magnetic ionic liquids including the 1-butyl-3-methylimidazolium tetrachloroferrate [Bmim][FeCl4] and 1-butyl-3-methylimidazolium thiocyanate [Bmim][SCN] were investigated for their interaction with the sulfur-rich compound, that is, dibenzothiophene. The ionic liquids samples were desulfurized and then regenerated with the co-solvent hexane. The samples were characterized and investigated with the analytical techniques including the Fourier-transform infrared spectroscopy, ultraviolet-visible absorption analysis, thermogravimetric analysis, and detailed analysis by Raman spectroscopy. The desulfurization results demonstrated that there is no significant influence of the dibenzothiophene molecules on the basic structures of ionic liquids. The regeneration results revealed that the high polarity of the co-solvent hexane successfully dissolve the dibenzothiophene and efficiently separated from the ionic liquids. Hence, the work present here in this study could be applied for the extractive removal of sulfur compounds from ionic liquids for their regeneration using high polarity co-solvent hexane.