Density, Viscosity, and Surface Tension of Aqueous 1-Methylpiperazine and Its Carbonated Solvents for the CO2 Capture Process

Physicochemical properties of amine solutions like density, viscosity, and surface tension results are indispensable for designing carbon dioxide (CO2) absorption and regeneration columns, and they are also crucial for modeling and simulation for CO2 capture applications using the postcombustion capture method. In the present work, the density and viscosity of 1-methylpiperazine (1-MPZ) solution are studied for the temperature range of 298.15 to 348.15 K. Surface tension measurements for temperatures ranging from 303.15 to 348.15 K are reported for various concentrations of 1-MPZ. To validate the instrumental accuracy and procedure, properties of aqueous 0.3 weight fraction (w) monoethanolamine (MEA) were first measured and compared with reported results before the study of 1-MPZ. The weight fraction of 1-MPZ was kept at 0.1, 0.2, 0.3, and 0.4 for the physical property study of unloaded aqueous 1-MPZ, and 0.3w was considered for CO2-loaded properties. The 1-MPZ solution was loaded with CO2 up to 0.45 mol CO2/mol amine. The Redlich–Kister equation for excess molar volume was used to correlate the measured density of the fresh and CO2-loaded solvents. The viscosity data of unloaded aqueous 1-MPZ and CO2-loaded aqueous 1-MPZ were correlated using the Grunberg–Nissan and modified Weiland models, respectively. Surface tension results of fresh and CO2-loaded 1-MPZ were fitted by a polynomial function. These new data and models are helpful for the design of postcombustion CO2 capture using 1-MPZ-based solvents and their blends.