Hypothesis

The stability of colloidal suspensions can be influenced by supersaturation of the supporting electrolyte with gas. It has been proposed that this effect can be attributed to the formation of nanobubbles on the surface of the colloidal particles, in turn influencing DLVO forces. While previous interpretations have focused primarily on van der Waals interactions, probing positively charged particles can provide complementary insight into electrostatic interactions.

Experiments

High-power water electrolysis creates an aqueous solution supersaturated with oxygen and hydrogen. We study the ability of this solution to influence the electrophoretic properties of positive nanoparticles as a function of the particle-gas ratio. Both the $\zeta$-potential and the effective hydrodynamic diameter of the resulting nanoentities were studied using dynamic light scattering for a range of nanoparticle sizes.

Findings

Gas-saturated solution interacts strongly with positive nanoparticles by decreasing and ultimately reversing the sign of their $\zeta$-potential, which we attribute to the nucleation of negatively charged bubbles at the solid-liquid interface. This leads to re-entrant condensation of the particles near their point of zero charge, as directly observed via an increase in hydrodynamic diameter and macroscopic aggregation. These results indicate that modulation of electrostatic interactions can be the dominant mechanism for gas-particle interactions in these systems.

中文翻译：

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纳米粒子与纳米气泡的相互作用：体积较大的纳米气泡驱动的late乳胶纳米粒子的电荷反转和折返缩合

假设

胶体悬浮液的稳定性可能会受到支持电解质与气体过饱和的影响。已经提出，该作用可归因于在胶体颗粒表面上形成纳米气泡，进而影响DLVO力。尽管先前的解释主要集中在范德华相互作用上，但是探测带正电的粒子可以提供有关静电相互作用的补充见解。

实验

大功率水电解产生的水溶液中充满了氧气和氢气。我们研究了该溶液影响正纳米颗粒的电泳性能与颗粒-气体比率的函数的能力。这俩$\zeta$使用动态光散射对一系列纳米粒子尺寸研究了所得纳米实体的电势和有效流体动力学直径。

发现

气体饱和溶液通过减少并最终反转其正负号而与正性纳米粒子发生强烈相互作用 $\zeta$-电势，我们将其归因于在固液界面处带负电的气泡的形核。如通过流体动力学直径的增加和宏观聚集的直接观察，这导致颗粒在其零电荷点附近的凹状凝结。这些结果表明，静电相互作用的调节可能是这些系统中气体-颗粒相互作用的主要机理。