The Properties Research On New Working Pairs Of 1-butyl-3-methylimidazolium Dibutylphosphate And Water/Alcohol

Absorption heat pump is an effective equipment for energy recycled, its operational performance depends on the properties of a working pair largely. LiBr-H2O and NH3-H2O, the widely used working pairs, have some problems difficult to resolve, such as strong corrosion to equipment, crystallization, high operation pressure, toxicity, et al. Therefore, the researches of new working pairs have received an increasing number of attentions.Ionic Liquid (IL) have many unique properties, such as thermal stability, a negligible vapor pressure, wide liquid range, strong solubility in many organic or inorganic substances. So, it is possible to be used as working pairs of absorption heat pump. In this paper, Vapor pressure, excess enthalpy (HE), specific heat capacity (Cp) and corrosion performance for three binary systems composed of ionic liquid (IL) 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) and water, or methanol or ethanol were measured. These properties will provide the basic data for the research of thermodynamic model and development of new working pair.The vapor pressures at different temperature and mole fraction of ionic liquid were measured by using the bubble point method. The experimental results indicate that these binary solutions are all negative deviation from the Raoult's Law for the solvents. The vapor pressure data were correlated with NRTL equation. The average deviations were 1.2%,1.3%and 1.8%, respectively. So NRTL equation could be used to correlate ionic liquid containing system. The excess enthalpy (HE) were measured at 298.15 K with different IL concentrations. The HE data were negative, which means the processes of mixing [BMIM][DBP] with water, methanol or ethanol are exothermal. The experimental data of heat capacities for the three systems show that the heat capacities decreased with the increase of molar fraction of [BMIM][DBP] at the same temperature and slightly increased with the increase of temperature at the same IL concentration. The polarization curve of 316L stainless steel in oxygen-free aqueous solution of [BMIM][DBP] and [MMIM][DMP] with IL mole fraction of 15% was measured at different temperature, and compared with the oxygen-free aqueous solution of LiBr at same temperature. The experimental result showed that the corrosion velocity of 316L stainless steel in ionic liquid is lower than that of LiBr-H2O obviously.To sum up, the three binary solutions containing ionic liquid, [BMIM][DBP]+ H2O/CH3OH/C2H5OH have the potential as working pairs.