Fundamental Research On Fixation CO₂Using Ionic Liquids

As one of the main contributor of the greenhouse effect, CO₂emission, mainly fromfossil fule combustion, is increasing with a rise in global energy consumption, whichposes a serious threat to both human living environment and ecological balance. Thuscapturing the CO₂from industrial waste gas is regarded as a good choice to reduce CO₂emission. Ionic liquids （ILs） have drawn significant attention to researchers owing totheir structural feature and tunable property. Then some CO₂affinity groups which couldenhance CO₂absorption are introduced into the cation or the anion of ILs.Three kinds of amino acid ionic liquids （AAILs）（[NH₂-emim][Lys],[NH₂-emim]-[Aba] and [NH₂-emim][Val]） were synthesized. The samples were characterized by mea-ns of FTIR,1HNMR, UV respectively. The physical properties were measured includingdensity, viscosity and electrical conductivity. The results show that as temperatureincreases, the density decreases slightly, the viscosity declines quickly, the conductivityincreases, and the solubility is related to the solvent polarity.The CO₂solubility in the samples was determined at different temperatures andpressures. The results present that the CO₂solubility increases with increasing pressureand improves initially with a rise in the absorption time; the CO₂solubility decreaseswith increasing temperature; at the same temperature, the trend is as follows:[NH₂-emim][Lys]>[NH₂-emim][Aba]>[NH₂-emim][Val].The henry’s constants and infinite dilution partical molar volumes could beconnected and the CO₂solubility could be caculated using the K-K equation associationon the CO₂solubility data. The results indicate that the henry’s constants increase with arise in temperature, which are consisted with the CO₂solubility data. The average relativeerror could be got at different temperatures by comparing the caculated and experimentaldata. The value of average relative error is within10%, which demonstrates that the CO₂solubility can be associated on the K-K equation.