Cryo-EM Visualization of Nanobubbles in Aqueous Solutions

Abstract

The detection of nanobubbles on surfaces is well established (e.g., AFM and optical microscopy methods), but currently no methods exist for the direct detection of bulk nanobubbles. Here, cryo-electron microscopy (cryo-EM) has been employed to observe bubbles in aqueous solutions for the first time. Nitrogen bubbles generated by a chemical reaction were observed in amorphous ice trapped between two carbon films. The cryo-EM images of bubbles showed the same features as predicted by theory. The fact that no bubbles were observed near an air-water interface suggests that bubbles may diffuse to the nearby air-water interface and escape. The estimate of the bubble diffusion coefficient is about 30-250 μm/s.

Plasma physics of liquids—A focused review

“…179,[197][198][199][200] Various solution preparation methods generally lead to number densities between 10 12 and 10 15 m À3 , [197][198][199][200] although values up to 1.9 Â 10 19 m À3 have been obtained. 186 Detection techniques include light scattering, 184 cryoelectron microscopy, 201 and a resonant mass measurement method that can distinguish the bubbles from liquid emulsion or solid nanoparticles. 202 Due to their small dimensions, nanobubbles have a negligible rising velocity compared to Brownian motion in the liquid.…”

A Henry's law method for generating bulk nanobubbles

“…A number of techniques have been reported for the generation of BNBs including single nanobubble electrolysis, [51][52][53][54][55] acoustic cavitation, 1,3,22 hydrodynamic cavitation, 56,57 fluidic oscillation, 58 nano-membrane filtration, 59 water-solvent mixing, 3,21,60,61 laser, 62,63 periodic pressure changes, 23 compression and decompression of gas, [64][65][66] and chemical reactions. 67 Each method has its own advantages and shortcomings. For example, electrochemical and chemical reaction methods are limited to specific gases, for instance, electrolysis of water can only produce hydrogen and oxygen nanobubbles.…”

“…Values of water vapour pressure67 and minimum operating absolute pressure inside water-filled syringe at different temperatures Open Access Article. Published on 22 July 2020.…”

The Nucleation Rate of Single O2 Nanobubbles at Pt Nanoelectrodes

“… 1 − 3 However, the technology used to visualize such surface nanobubbles has been very recently developed. 2 , 4 − 6 The biggest concern that surface nanobubbles cause is their generation in chemical reactions, such as electrolysis 7 and catalysis. 8 Nanobubbles nucleating on top of reacting surfaces or electrodes influence the efficiency of chemical reactions since they partially block the reactive surface and consequently impede the reaction of interest.…”