Stability of Nanobubbles
Stability of Nanobubbles
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DOI：
10.1089/ees.2018.0203
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发表时间：
2018-09-26
影响因子：
1.8
通讯作者：
Batagoda, Janitha H.
中科院分区：
文献类型：
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作者：
Meegoda, Jay N.;Hewage, Shaini Aluthgun;Batagoda, Janitha H.
由于在液体中稳定存在数周以上，纳米气泡在许多科学和工程领域具有广泛的应用。为了有效和有效地使用这些气泡，重要的是要知道它们长期稳定的原因。因此，进行了全面的实验室研究，以确定纳米气泡的气泡尺寸分布和zeta电位，首先使用四种不同的气体（测试系列I），然后使用不同的盐浓度、pH值和溶液温度（测试系列II）。来自测试系列I的实验结果表明，平均气泡尺寸取决于气体在水中的溶解度，并且zeta电位取决于气体在水/气体界面处产生OH-离子的能力。来自测试系列II的实验结果表明，具有高负zeta电位的气泡可以在高pH、低温和低盐浓度的溶液中产生。高pH溶液产生较小但稳定的纳米气泡。气泡直径随着盐浓度的增加而略有增加。然而，气泡大小并没有表现出相当大的依赖于溶液温度。长期试验表明，随着时间的延长，气泡的zeta电位降低，气泡尺寸增大。尽管由于气体扩散，气泡尺寸预计会随时间减小，但结果表明气泡尺寸会增加。这是因为由于布朗运动引起的zeta电位和气泡运动的降低，布朗运动导致气泡随时间聚结以形成更大的气泡。
With stable existence in liquids for over several weeks, nanobubbles have an extensive range of applications across many fields of science and engineering. For an effective and functional use of these bubbles, it is important to know the reason for their long-term stability. Therefore, a comprehensive laboratory investigation was performed to determine bubble size distributions and zeta potentials of nanobubbles, first with four different gases (test series I), then with different salt concentrations, pH levels, and temperatures of the solution (test series II). Experimental results from test series I showed that the average bubble size depended on the gas solubility in water, and zeta potential depended on the ability of the gas to generate OH- ions at the water/gas interface. Experimental results from test series II showed that bubbles with high negative zeta potentials can be generated in solutions of high pH, low temperatures, and low salt concentrations. The high pH solutions produced smaller but stable nanobubbles. Bubble diameter slightly increased with increasing salt concentration. However, bubble size did not show considerable dependence on solution temperature. Long-term tests showed that with time zeta potential of bubbles decreased while the bubble size increased. Even though bubble sizes are expected to decrease with time due to gas diffusion, results indicate increased bubble sizes. This is because of decrease in zeta potential and bubble movement due to Brownian motion which causes bubble coalescence over time to form larger bubbles.