The experimental study on influence of zwitterionic compounds on solubility of lithium bromide in water

Finding the proper additive to conventional lithium bromide aqueous solution to improve the performance of the efficiency of refrigeration equipment is an important issue of research related to the absorption refrigeration technology. In this study, the zwitterionic compounds (ZIs): 3-(triethylammonio)propane-1-sulfonate, [N222C3S], 4-(triethylammonio)-butane-1-sulfonate, [N222C4S], 3-(tributylammonio)propane-1-sulfonate, [N444C3S], 4-(tributylammonio)butane-1-sulfonate, [N444C4S], 4-(tributylphosphonio)butane-1-sulfonate, [P444C4S] and 3-(1-pyridinio)-1-propanesulfonate, [PyC3S] were investigated as anti-crystallization additives for {LiBr (1) + water (2)} system, conventionally used as a working pair in absorption refrigeration technology. For this purpose, the solubility of lithium bromide in water has been determined in the presence of zwitterionic compound. The solubility measurements have been carried out using dynamic method at wide temperature and composition range for different ZI to LiBr mass fraction, 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. Based on experimental SLE data, the best additive was selected, further measurements of the vapor - liquid equilibria will be carried out.