(163bm) Measurement of the Infinite Dilute Activity and Diffusion Coefficients of Small Molecule Solvents in Cross-Linked Polyvinyl Alcohol by Inverse Gas Chromatography

The infinite dilute activity and diffusion coefficients of water, methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol in cross-linked polyvinyl alcohol were measured in the temperature range of 363.15K-403.15K by inverse gas chromatography. The cross-linked PVA was obtained by dissolving PVA prepolymer, cross-linking agent and catalyst in water solvent and characterized by FTIR spectra. The van Deemter equation is used to obtain diffusion coefficients of solvents from the variation of chromatographic peak under the different flow rates of carrier gas. The interdependence on the infinite dilute coefficient and temperature follows Arrhenius equation well. Diffusion constant and activation energy are obtained from the Arrhenius equation. The experimental results showed that (1) the activity coefficient values of water were much lower than those of other solvents dealt with this work in cross-linked PVA, (2) the infinite dilute activity coefficients of alcohols increased with the rising of temperature in cross-linked PVA and (3) the infinite dilute activity coefficients of all these solvents increased distinctly after cross-linking. The experimental results also showed that (1) the infinite dilute diffusion coefficients of solvents increased with the rising of temperature in cross-linked PVA and (2) the infinite dilute diffusion coefficients of all these solvents increased after cross-linking. The authors greatly appreciate the financial supports of the Major State Basic Research Program of China (No. 2003CB615701), National Natural Science Foundation of China (No. 20576059), SINOPEC Foundation (No. X505002) and CNPC Innovation Foundation.