Electrically controlled cloud of bulk nanobubbles in water solutions

Abstract

Using different experimental techniques we visualize a cloud of gas in water that is produced electrochemically by the alternating polarity process. Liquid enriched with gas does not contain bubbles strongly scattering visible light but its refractive index changes significantly near the electrodes. The change of the refractive index is a collective effect of bulk nanobubbles with a diameter smaller than 200 nm. Any alternative explanation fails to explain the magnitude of the effect. Spatial structure of the cloud is investigated with the optical lever method. Its dynamics is visualised observing optical distortion of the electrode images or using differential interference contrast method. The cloud covers concentric electrodes, in a steady state it is roughly hemispherical with a size two times larger than the size of the electrode structure. When the electrical pulses are switched off the cloud disappears in less than one second. The total concentration of gases can reach very high value estimated as 3.5 × 1020 cm−3 that corresponds to an effective supersaturation of 500 and 150 for hydrogen and oxygen, respectively.

Gas nanobubble dispersions as the important agent in environmental processes – generation methods review

“…They assumed this fact is connected with presence of bubbles, but only when DLS methods were discovered, the correct interpretation of such behaviour could have been studied. As such the generation of nanobubbles using this method was performed and interesting results were recorded (Kikuchi et al ., 2001a; 2001b; 2006a; 2006b; 2009; 2007; Postnikov et al ., 2016a; 2016b; 2017; 2018). As one can see, up to this time, two distinct (both in time and geopolitical location) research teams has tackled this problem.…”

“…Research carried out by Postnikov et al (2016a; 2016b; 2017; 2018) concerning water electrolysis provide us with information that nanobubbles can be generated using alternating polarity (AP) electrolysis of water. When such method is applied, both hydrogen and oxygen are generated on the same electrode as it periodically becomes anode or cathode.…”

“…For example, Postnikov et al . (2017) reports that square pulse frequency of the order of 200 kHz and the amplitude of 10 V were applied to observe optical distortion of the electrodes. Such distortion comes from bubbles generated on and gathered near the electrode and is expressed by the change in the refractive index of liquid surrounding the electrode.…”

Explosion of Microbubbles Generated by the Alternating Polarity Water Electrolysis

“…On the other hand, the AP electrolysis generates so many NBs that one can easily observe collective effects produced by them. Liquid enriched with NBs changes the refractive index around the electrodes that can be observed by shading techniques [10] or even by direct observation of optical distortion [21]. The latter method allows estimation of the concentration of NBs [22] that can be as high as ∼10 21 m −3 .…”

Исследование Ударных Волн В Электрохимическом Микроактюаторе

“…23ударной волны по следующей причине. Во время периода инкубации в жидкости образуется облако нанопузырьков над электродами[6]. Это область с плотностью, меньшей, чем у воды, поэтому она играет роль демпфера и не дает возможности сформироваться ударной волне.…”