Ultrasonic cavitation did not occur in high-pressure CO ₂ liquid

Abstract Kuijpers’s study, published in Science under the title “Cavitation-induced reactions in high-pressure carbon dioxide,” explores the phenomenon of acoustic cavitation in high-pressure liquid CO 2 . However, an analysis of the study suggests that the vapor pressure within bubbles in high-pressure liquid CO 2 cannot remain constant or be balanced by static pressure, challenging the fundamental conditions required for acoustic cavitation. A critical prerequisite for cavitation is that the sound pressure must be proportional to the hydrostatic pressure, a condition that does not hold in Kuijpers’s experiments. This raises questions about the interpretation of the ultrasonic effects reported in the study, suggesting that they may not be caused by cavitation. The controversy surrounding acoustic cavitation in high-pressure CO 2 is of significant academic interest, as it has implications for fields such as chemical processing, materials science, and ultrasound-assisted reactions. While the physical properties of supercritical CO 2 closely resemble those of liquid CO 2 , experiments conducted with supercritical CO 2 indicate that metal corrosion and polymer formation can occur in the absence of cavitation. Moreover, computational simulations have further demonstrated the mechanical effects of ultrasound in both liquid and supercritical CO 2 , reinforcing the need for a more precise understanding of the mechanisms involved.