Frenkel Line and Solubility Maximum in Supercritical Fluids

A new dynamic line, the Frenkel line, has recently been proposed to separate the supercritical state into rigid-liquid and non-rigid gas-like uid. The location of Frenkel line on the phase diagram is unknown for real uids. Here, we map the Frenkel line for three important systems: CO2, H2O and CH4. This provides an important demarcation on the phase diagram of these systems, the demarcation that separates two distinct physical states with liquid-like and gas-like properties. We find that the Frenkel line can have similar trend as the melting line above the critical pressure. Moreover, we discuss the relationship between unexplained solubility maxima and Frenkel line, and propose that the Frenkel line corresponds to the optimal conditions for solubility.