Stability of nanobubbles in different salts solutions
Stability of nanobubbles in different salts solutions
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DOI：
10.1016/j.colsurfa.2020.125669
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发表时间：
2021-01-20
影响因子：
5.2
通讯作者：
Meegoda, Jay N.
中科院分区：
文献类型：
--
作者：
Hewage, Shaini Aluthgun;Kewalramani, Jitendra;Meegoda, Jay N.
采用去离子水、NaCl、Na 2SO 4、Na 3 PO 4、CaCl 2和FeCl 3研究了不同离子价态下纳米气泡在电解质溶液中的稳定性。使用水力空化产生纳米气泡，并测试气泡的尺寸和zeta电位。所有样品均稳定一周，气泡尺寸或zeta电位值均无显著偏差。六种样品的粒径和zeta电位的变化可以归因于溶液的性质，主要取决于溶液的pH值和阳离子的价态。离子分布显示，在气泡表面的阳离子浓度高于本体的阳离子浓度，证实了在低价阳离子吸附下，对于中性和高pH值（>= 4），气泡带负电荷。高价阳离子具有中和或完全逆转气泡电荷的潜力。阴离子或共离子对表面电位或表面电荷的影响最小。计算得到的气泡内压偏高，表明纳米气泡溶液的表面张力应低于水的表面张力。相互作用能分布显示，除了NaCl在5 nm分离距离处具有1.87 x 10（-20）J势垒外，所有溶液都没有克服吸引性货车范德华力的显著能垒。然而，对于记录的稳定气泡，范德华吸引力的计算产生了不切实际的值，这表明用于计算的Hamaker常数在纳米气泡气液界面可能无效。货车力。这表明，纳米气泡应该包含特殊的界面特性，需要仔细研究和评估。
The stability of nanobubbles in electrolyte solutions under different ion valence values was studied using deionized water, NaCl, Na2SO4, Na3PO4, CaCl2, and FeCl3. Nanobubbles were generated using hydrodynamic cavitation, and bubbles were tested for size and zeta potential. All the samples were stable for one week with no significant deviation in either bubble size or zeta potential values. The variation of size and zeta potential among six samples can be attributed to the solution properties and was mainly dependent on solution pH and the cation valency. The ion profiles revealed that the cation concentration at the bubble surface was higher than that of bulk, confirming that the bubbles were negatively charged for neutral and high pH values (>= 4) under low valency cation adsorption. The high valency cations have the potential to neutralize or completely reverse the bubble charge. Anions or co-ions have minimal effect on the surface potential or the surface charge. The calculated internal pressures of bubble were unrealistically high, suggesting that the surface tension should be lower than that of water for nanobubble solutions. The interaction energy profile shows no significant energy barrier that overcomes the attractive van der Waals forces for all the solutions, except NaCl which had a 1.87 x 10(-20) J barrier at a 5 nm separation distance. However, with the recorded stable bubbles, the calculation of the attractive van der Waals forces produced unrealistic values indicating that the Hamaker constant used for the calculation may not be valid at the nanobubble gas-liquid interface. This revealed that nanobubbles should contain exceptional interfacial properties that need to be carefully investigated and evaluated.