Kinetic inhibition effect of Type I and III antifreeze proteins on unidirectional tetrahydrofuran hydrate crystal growth

Experiments were performed to evaluate the kinetic inhibition effect of Type I and Type III antifreeze proteins (AFPs), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) on the growth of tetrahydrofuran (THF) clathrate hydrate crystals using the unidirectional growth technique. The crystal growth interface shifted under an applied temperature gradient over a given time. Type I AFP was the most effective kinetic inhibitor, followed by PVP, Type III AFP and PVA. The morphology of the THF hydrate was affected significantly by the concentration of Type I AFP. At low concentrations of Type I AFP, a large hexagonal plate-like crystal formed. At high concentrations, the growth interface became relatively flat. Conversely, at low concentrations of Type III AFP, the morphology of the THF hydrate crystal was unaffected by the additive.