Generation and stability of bulk nanobubbles: A review and perspective

Zhou, Limin; Wang, Shuo; Zhang, Lijuan; Hu, Jun

doi:10.1016/j.cocis.2021.101439

Cited by 91 publications

(52 citation statements)

References 89 publications

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“…Owing to such peculiar properties, nanobubbles have wide range of applications in the field of wastewater treatment [1] , [2] , medical application [3] , food processing [4] , environmental sectors [5] , bio-engineering sectors [6] , flotation [7] , therapeutic delivery [8] . Despite such overwhelming applications, the fundamental understanding of nanobubble generation [9] and a unique characterization technique to distinguish nanobubbles from the particle and nanodroplet [10] are still under infancy. Broadly, nanobubble generation methods include acoustic cavitation [11] , porous membrane [12] , repeated compression and decompression [13] , [14] , electrolysis [15] , external electric field [16] and alternating magnetic field [17] .…”

Section: Introductionmentioning

confidence: 99%

Does salting-out effect nucleate nanobubbles in water: Spontaneous nucleation?

Agarwal

Trivedi

Nirmalkar

2022

Ultrasonics Sonochemistry

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Highlights Nanobubble density during salting-out effect increases with salting-out parameter. An ultrasound field with a high amplitude destroys the nanobubbles in salt solution. R.I. of nanobubbles in NaCl and AlCl 3 were estimated to be 1.012 and 1.302, respectively. The NBs during salting-out effect are observed to be stable only for up to three days.

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Section: Introductionmentioning

confidence: 99%

Does salting-out effect nucleate nanobubbles in water: Spontaneous nucleation?

Agarwal

Trivedi

Nirmalkar

2022

Ultrasonics Sonochemistry

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“…16−18 With the continuous research on nanobubbles, diverse methods for nanobubble generation based on four common mechanisms: hydrodynamic, acoustic, particle, and optical, have been proposed and investigated over the past decades, 9 including hydrodynamic cavitation, ultrasonic fragmentation, electrolysis, gas−liquid mixing, external electromagnetic field, porous membranes, temperature gradients, and so on. 19,20 For example, the BNBs prepared by Azevedo et al were produced by dissolving air in water in saturators followed by depressurization/hydrodynamic cavitation of the air-saturated water in a needle valve. 21 Hoon et al used motor-generated mechanical motion for gas−liquid mixing to generate BNBs, which could exist stably for 24 h. 22 Nirmalkar et al used a 20 kHz probe ultrasound processor to induce pressure variations in solutions spiked with sodium dodecyl sulfate, leading to the formation of bubbles.…”

Section: ■ Introductionmentioning

confidence: 99%

Generation of Bulk Nanobubbles by Self-Developed Venturi-Type Circulation Hydrodynamic Cavitation Device

Cui

Sun

et al. 2021

Langmuir

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Bulk nanobubbles (BNBs) have attracted substantial interest from academia and industry owing to their peculiar properties and extensive potential applications. However, a scalable engineering method needs to be developed. Herein, we developed a nanobubble generator based on venturi-type recirculating hydrodynamic cavitation. The existence of nanobubbles produced by our generator was confirmed using physicochemical test methods, including the Tyndall effect, multiple freeze–thaw degassing experiments, and trace metal analysis. Subsequently, the effects of different operating parameters (circulation time and operating pressure) on bulk nanobubble production and properties, as well as their stability, were investigated. The results suggest that the characteristics of BNBs varied with the circulation time (5–20 min) and operating pressure (2–5 bar). However, all the particle size distribution of BNBs had a bimodal distribution with a mean diameter of 180–210 nm for the different circulation time and operating pressures. For example, by increasing the circulation time from 5 to 20 min, the peak value of size distribution decreased from 333/122 nm to 218/52 nm, and the average sample scattering signal count rate (Avg. Count Rate) increased from 133 to 303 Kcps. The evaluation of the stability of the BNBs formed for the circulation time of 15 min and the operating pressure of 3 bar showed that they could continue existence and stability in the suspension for 72 h. The study results might provide a valuable method for further investigation of industrial applications of venturi-type nanobubble generators.

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“…[3][4][5] Although solid-state nanoparticles are to be added to the liquid sample from the outside, long-lived nanometer-sized gas bubbles steadily exist in water and aqueous electrolyte solutions under normal conditions, see the recent reviews. [6][7][8][9][10][11][12] The influence of gas nanobubbles on the short-range molecular structure of water has also been studied in several works, [13][14][15][16] where various mechanisms for the stabilization of gas nanobubbles under normal conditions were considered. We in our group also investigated different mechanisms of stabilization of nanobubbles in the liquid bulk.…”

Section: Introductionmentioning

confidence: 99%