Experimental study of the phase equilibrium diagram of the binary mixture “Freon R404A-acetone”

This paper presents the results of an experimental study on the phase equilibrium diagram of the binary system “Freon R404A–acetone” at a temperature of T = 356 K. These results are crucial for selecting optimal thermodynamic conditions for the supercritical fluid extraction of acetone from aqueous solutions using R404A freon as an extractant. This process is particularly relevant for addressing wastewater disposal challenges at the Bisphenol-A production facility at PJSC Kazanorgsintez (Russian Federation), which manufactures phenol and acetone. The studied binary mixture exhibits type I–II phase behavior, characterized by the termination of the two-phase “liquid–vapor” equilibrium at critical points corresponding to various temperatures, a continuous critical curve, and a gas-phase region of complete miscibility beyond the binodal. The ability to approach the critical point-where the mixture displays anomalous changes in properties- may significantly enhance the efficiency of the supercritical fluid extraction process compared to systems exhibiting type V phase behavior. At the studied temperature, the critical pressure was determined to be Pkр = 4.14 MPa.