The influence of bromide-based ionic liquids on solubility of {LiBr (1) + water (2)} system. Experimental (solid + liquid) phase equilibrium data. Part 1

Abstract

In this work, nine ILs are investigated as anti-crystallization additives to (LiBr+water) binary systems conventionally used as a working pair in absorption refrigeration technology. The solubility of {LiBr (1)+IL (2)+water (3)} ternary systems within wide temperature and composition range was determined by the dynamic method. In this work, the following ILs: 1-ethyl-1-methylmorpholinium bromide, [C1C2MOR][Br], 1-butyl-1-methyl-morpholinium bromide, [C1C4MOR][Br], 1-hexyl-1-methylmorpholinium bromide, [C1C6MOR][Br], 1-butyl-3-methylimidazolium bromide, [C1C4IM][Br], 1-ethyl-1-methyl-piperidinium bromide, [C1C2PIP][Br], 1-butyl-1-methylpiperidinium bromide, [C1C4PIP][Br], 1-butyl-1-methyl-pyrrolidinium bromide, [C1C4PYR][Br], 1-butylpyridinium bromide, [C4Py][Br] and tri(ethyl)-butylammonium bromide, [N2,2,2,4][Br] were investigated. The experimental (solid+liquid) phase equilibria have been determined for different IL to LiBr mass fractions from w2=(0.1 to 0.3). For all of the tested system, the transition point between lithium bromide dihydrate and monohydrate form was observed. Additionally, the simple model based on the multicomponent Redlich-Kister equation and a reference state of pure chemical compounds was used to successfully describe solubility of lithium bromide in aqueous systems containing an ionic liquid. The influence of ILs cation's core on the crystallization temperature of aqueous lithium bromide system was discussed and the best IL as an anti-crystallization additive has been proposed.