文獻名：Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water

作者： Yali Zhou¹, Zhenyao Han¹, Chunlin He¹, Qin Feng¹, Kaituo Wang¹, Youbin Wang¹, Nengneng Luo¹, Gjergj Dodbiba², Yuezhou Wei¹, Akira Otsuki^3,4 and Toyohisa Fujita^1,

¹College of Resources, Environment and Materials, Guangxi University, Nanning 530004, China

²Graduate School of Engineering, The University of Tokyo, Bunkyo 113-8656, Japan

³Ecole Nationale Supérieure de Géologie, Geo Ressources UMR 7359 CNRS, University of Lorraine, 2 Rue du Doyen Marcel Roubault, BP 10162, 54505 Vandoeuvre-lès-Nancy, France

⁴Waste Science & Technology, Luleå University of Technology, SE 971 87 Luleå, Sweden

摘要：Nanobubbles have many potential applications depending on their types. The long-term stability of different gas nanobubbles is necessary to be studied considering their applications. In the present study, five kinds of nanobubbles (N₂, O₂, Ar + 8%H₂, air and CO₂) in deionized water and a salt aqueous solution were prepared by the hydrodynamic cavitation method. The mean size and zeta potential of the nanobubbles were measured by a light scattering system, while the pH and Eh of the nanobubble suspensions were measured as a function of time. The nanobubble stability was predicted and discussed by the total potential energies between two bubbles by the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The nanobubbles, except CO₂, in deionized water showed a long-term stability for 60 days, while they were not stable in the 1 mM (milli mol/L) salt aqueous solution. During the 60 days, the bubble size gradually increased and decreased in deionized water. This size change was discussed by the Ostwald ripening effect coupled with the bubble interaction evaluated by the extended DLVO theory. On the other hand, CO₂ nanobubbles in deionized water were not stable and disappeared after 5 days, while the CO₂ nanobubbles in 1 mM of NaCl and CaCl₂ aqueous solution became stable for 2 weeks. The floating and disappearing phenomena of nanobubbles were estimated and discussed by calculating the relationship between the terminal velocity of the floating bubble and bubble size

關鍵詞：extended DLVO theory; mean size; zeta potential; Ostwald ripening effect; Stokes equation