Sedimentation and density gradients near the liquid–liquid critical solution point in high gravitational fields

Experiments in the ultracentrifuge and theoretical analysis both strongly suggest that, in a binary liquid mixture near its liquid–liquid critical solution point, the sedimentation rate diverges approximately as (T−Tc)−0.6. As a result of the divergence of the sedimentation rate, a density inversion (a negative value of dρ/dh) can occur at temperaures substantially above the equilibrium critical solution temperature. The turbulence resulting from the instability can give the appearance of phase separation.