Heterogeneous nucleation of bubbles at solid surfaces in gas-supersaturated aqueous solutions

Abstract

CH 4, Ar, and N 2 supersaturation thresholds for cavitation in saturated aqueous solutions of succinic acid, potassium nitrate, and potassium chloride were determined at room temperature in the presence and absence of crystalline precipitates. To avoid the introduction and interference of preformed gaseous nuclei, crystals were formed in situ by cooling prior to decompression, after the solutions had been equilibrated with gas at elevated pressure and temperature. In the succinic acid and potassium nitrate systems, bubbles first occurred during decompressions in exclusive association with crystals. At ambient pressure, such cavitation occurred with supersaturations below 10 atm, while cavitation without crystals required supersaturations over 100 atm. In contrast, cavitation with potassium chloride crystals required supersaturations exceeding 100 atm. It is concluded that thresholds with succinic acid and potassium chloride crystals accurately reflected particular properties of the crystal-liquid interfaces, while the low thresholds observed with potassium nitrate crystals may also have reflected certain effects of the preceding crystallization processes per se. Results may be of particular biological significance because thresholds with succinic acid crystals at atmospheric pressure were within 5 atm of the supersaturations which elicit bubble-induced trauma in animals and man.