Document Type
Article
Publication Date
11-3-2026
Abstract
Present to a finite degree in atmospheric liquids, nanoscale air bubbles are fundamentally different in structure from their microscopic counterparts and their effects on chemical reactions have been relatively understudied. The objective of this study was to assess how nanobubbles stabilized by amphiphilic molecules of different ionic nature—including cationic cetyltrimethylammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS) and nonionic polyoxyethylene sorbitan monolaurate (Tween 20)—affect crystallization from metastable supersaturated solutions. These experiments were preceded by thorough spectroscopic, refractometric and light scattering characterization of ultrapure water containing surfactant-stabilized nanobubbles. 1H and 13C NMR analyses suggested that the ionic surfactant molecules orient with tails toward the air pockets of the nanobubbles, while headgroups remain immersed in the water phase, with further indications that nonionic Tween 20, immune to charge compensation through various hydration and counterion complexation mechanisms, may penetrate the gaseous milieu inside the nanobubbles even deeper with its tails. FTIR analyses showed a consistent decrease in the hydroxyl stretching mode energy with the introduction of the nanobubbles, conforming to the model of the interface populated by intense charge separation and relatively high concentration of free hydroxyls and other transiently immobilized chemical species. This charge separation brought about by the nanobubble formation, along with the segregation of hydroxides within the Stern layer of the interface, explained the increase in the total electronic polarizability of the system and the ensuing increase in the bulk refractive index. Supplementation of ultrapure water with any of the three surfactants tested significantly reduced the nucleation lag time for crystallization of hydroxyapatite from metastable solutions supersaturated with respect to it. The generation of nanobubbles in surfactant solutions further decreased this lag time, suggesting that nanobubbles are not passive constituents of chemical solvents, but rather potentially active promoters of chemical reactions taking place in them. The precipitates formed in nanobubble-containing solutions also differed in terms of crystallinity, particle size and morphology, likely as a consequence of the enhanced nucleation rate. Correspondingly, both crystallinity and the particle size showed the tendency to decrease with the introduction of nanobubbles to the solutions, while the anisotropic growth promoted by the crystal-face-specific adsorption of surfactants was suppressed in the presence of the nanobubbles. These crystallographic and morphological effects were directly related to the nucleation-promoting capacity and most critical in SDS solutions, while least apparent in Tween 20 ones. In conclusion, nanobubbles should be increasingly taken into account for their effects on chemical reactions proceeding in solutions harboring them.
Recommended Citation
Uskoković, V. Physicochemical characterization of surfactant-stabilized nanobubbles and their effect on crystallization from metastable supersaturated solutions. J Nanopart Res 28, 286 (2026). https://doi.org/10.1007/s11051-026-06793-w
Peer Reviewed
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The author
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This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
This article was originally published in Journal of Nanoparticle Research, volume 28, in 2026. https://doi.org/10.1007/s11051-026-06793-w