Refined Analysis of the Nucleation Curves for Ice and Gas Hydrate Generated from the Linear Cooling Ramp Method

We previously experimentally determined the nucleation curves of ice and clathrate hydrates using the linear cooling ramp method, and we used Classical Nucleation Theory (CNT) to determine the thermodynamic parameter (the Arrhenius activation barrier) and the kinetic parameter (the frequency of the system’s attempt for nucleation). However, our past analyses using CNT led to a curvature in a (ln J – Δ S eq Δ T / kT ) versus (1/ T Δ T 2 ) plot, which rendered deduction of the thermodynamic and kinetic parameters from the slope and the intercept of the plot challenging and consequently limited the utility of CNT in the analyses of the nucleation data. In the present study, we improved the analysis by adjusting the size of the “unit building block” in CNT, the only parameter that could be adjusted and still impact the linearity of a (ln J – Δ S eq Δ T / kT ) versus (1/ T Δ T 2 ) plot. The results showed that the linearity of the plot was highly sensitive to the choice of the size of the “unit building block”, and most samples in our previous studies achieved good linearity by using this approach. However, the linearity of the plot in the presence of the two most effective ice nucleation promoters investigated, Snomax and dispersed AgI suspension, remained poor, which offered new insights and highlighted the limitations of CNT in the presence of effective nucleation promoters.