SOLUBILITY OF CARBON-DIOXIDE IN MIXTURES OF PROPYLENE CARBONATE AND TRIETHANOLOAMINE

Solubility of CO2 in a new absorbent, propylene carbonate modified by triethanoloamine (TEA), was determined by a static method. The scheme of the experimental setup is shown in Fig. 1. The measurements were ca rried out in the temperature range of 10-40 degrees C, in the pressure range up to 1.7 bar, and in the TEA concentration range of 0-10% wt. The results are shown in Fig. 2 in the form of diagrams of CO2 solubil ity alpha versus CO2 partial pressure p. The functions p(i) = f(alpha ) are linear for both pure propylene carbonate and its mixtures with T EA. This suggests physical character of absorption. Addition of TEA to propylene carbonate increases significantly the solubility of CO2 (Ta ble 4). The solubility of CO2 in propylene carbonate has been correlat ed with temperature and CO2 partial pressure (Eq. (5)); the solubility of CO2 in propylene carbonate/TEA mixtures has been correlated with t emperature, CO2 partial pressure and TEA concentration (Eq. 6). On the basis of the regular solutions theory for mixed solvents [12, 13] and the Hildebrand-Scatchard equations ((8), (9)) the solubility paramete r was determined. This parameter changes significantly both with tempe rature and with TEA concentration. For this reason the CO2-propylene c arbonate/TEA system cannot be regarded as a regular one.