Ion Exclusion at the Ice-Water Interface Differs from That at the Hydrate-Water Interface: Consequences for Methane Hydrate Exploration

Abstract

When water-ice grows into salt solutions ion species are excluded by the ice differentially due to non-identical solubility in the ice lattice. This causes an electrical potential across the interface during the ice growth process, initially named the Workman Reynolds Freezing Potential, and may be one of the causes for lightning. However, by measuring the voltage between the ice and water, we have found that when tetrahydrofuran hydrate crystals are grown into salt solutions all ion species are excluded equally and the potential does not manifest. When considered together, this marked difference in ion exclusion scenarios may have ramifications for hydrate exploration because of the chlorine anomaly, which is often used as an indicator of the presence of hydrate reserves.