Study of self-association of water in supercritical CO 2 by Monte Carlo simulation: Does water have a specific interaction with CO 2?

Abstract

The extent of the self-association of water in supercritical CO 2 has been investigated in a wide range of density and temperature by the test particle insertion technique. The results show that the association constant for water decreases with temperature and weakly depends on CO 2 density. This weak density dependence provides evidence for the lack of a strong specific CO 2–water interaction. Comparing calculated association constants with its gas-phase values shows that the association constant is at most ca. 38% lower than its gas-phase value in the high density–low temperature region. Inspection of the simulated radial distribution functions revealed that forming modest water–CO 2 complexes does not result in substantial interference in H-bonding of water molecules.