Vehmas Tapio, Makkonen Lasse
VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT Espoo, Finland.
ACS Omega. 2021 Mar 16;6(12):8021-8027. doi: 10.1021/acsomega.0c05384. eCollection 2021 Mar 30.
Water containing suspended nanobubbles is utilized in various applications. The observed lifetime of suspended nanobubbles is several weeks, whereas, according to the classical theory of bubble stability, a nanosized bubble should dissolve within microseconds. Explanations for the longevity of nanosized bubbles have been proposed but none of them has gained general acceptance. In this study, we derive an explanation for the existence of metastable nanobubbles solely from the thermodynamic principles. According to our analysis, the dissolution of nanosized aqueous bulk bubbles is nonspontaneous below 180 nm diameter due to the energy requirement of gas dissolution. Hydrophobic surfaces have a further stabilizing effect, and the dissolution becomes nonspontaneous in surface nanobubbles having a diameter below 600 nm.
含有悬浮纳米气泡的水被用于各种应用中。观察到的悬浮纳米气泡的寿命为几周，然而，根据经典的气泡稳定性理论，纳米尺寸的气泡应该在微秒内溶解。已经有人提出了关于纳米气泡长寿的解释，但没有一个得到普遍认可。在本研究中，我们仅从热力学原理推导出了亚稳态纳米气泡存在的解释。根据我们的分析，由于气体溶解所需的能量，直径小于180nm的纳米尺寸的大量水气泡的溶解是非自发的。疏水表面具有进一步的稳定作用，并且在直径小于600nm的表面纳米气泡中，溶解变得非自发。
