Aminopropyl functional ionic liquids exhibit a good selectivity for carbon dioxide(CO2)absorption.In order to reveal the effects of water concentration on the CO2 solubility in 1-aminopropyl-3-methylimidazolium bromide([APMim]Br)aqueous solutions

the experiments based on an isochoric technique by using a high-pressure quartz glass cell were performed to test the solutions of 55.90%

65.78%

76.80% and 85.76% water mass fractions.The equilibrium data for CO2 solubility in these aqueous solutions were obtained in range of 278.15-348.15 K and 0.1-4.5 MPa.A mathematical model that can correctly reflect the experimental data changes was obtained by mechanism analysis of absorption.The results indicated that the chemical absorption mechanism is predominant at lower pressure while the CO2 solubility can be doubled comparing to the chemical one when the water concentration increased and the physical absorption ability prevailed.In 65%-85% water mass fraction

the solutions have an excellent CO2 absorption and release ability in considerable large temperature and pressure ranges and may have a promised future for engineering application.