Freezing-nucleation in aqueous solutions of clathrate forming gases

Abstract

Experiments were performed to determine the extent to which the nucleating abilities of artificialand natural freezing nuclei are influenced by the presence of clathrate-forming gases dissolved inwater. Changes in the supercooling requirement of water saturated with argon, or propane weredetermined for several nucleant-gas combinations using the drop freezing technique. Thenucleants responded differently indicating that the influence of these clathrate-forming gases onheterogeneous freezing nucleation is not due to changes in the bulk water structure, but resultsfrom modifications at the nucleant-embryo interface. The measurements revealed an irreversibleimprovement in nucleating ability for some combinations and demonstrated that these gases canreduce the supercooling requirement of certain nuclei by as much as 3°C.