Micro–Nano Bubble Technology and Its Applications

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 5 June 2024 | Viewed by 1235

Special Issue Editors


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Guest Editor
School of Environmental Science & Engineering, Tianjin University, Tianjin 300350, China
Interests: drinking water security; water pollution control; sustainable urban drainage systems; water environment carrying capacity

E-Mail Website
Guest Editor
School of Environmental Science & Engineering, Tianjin University, Tianjin 300350, China
Interests: aeration; micro–nano bubble; free radical; drinking water treatment; biofilm removal; advanced oxidation

Special Issue Information

Dear Colleagues,

The main characteristics of traditional aeration technology commonly used in water treatment are that it can produce bubbles that possess a large specific surface area and high mass transfer efficiency, increase the concentration of dissolved oxygen, and achieve the purpose of promoting the degradation of organic matter by aerobic microorganisms. Micro–nano bubbles (particle size between "10~50 μm" and "≤200 nm") have been widely used in medical, cleaning, agricultural cultivation and other fields in recent years because of their smaller particle size, larger surface area, stable existence in water for a few hours to a few days, producing a large number of hydroxyl radicals after collapse and other characteristics. Micro–nano bubble generation methods include hydraulic cavitation, dissolved gas release, ultrasonic cavitation and electrolysis. The characterization parameters of micro–nano bubbles mainly include the particle size, Zeta potential, concentration and so on. After a large number of experiments, researchers have concluded that the main factors affecting micro–nano bubbles and hydroxyl radicals are the air source, ultrasonic stimulation, pH and so on. These advances in micro–nano bubble technology can provide theoretical support for the stable generation of micro–nano bubbles and the generation of more hydroxyl radicals, thereby improving the treatment effect.

This Special Issue entitled "Micro–nano Bubble Technology and its Applications" is looking for high-quality works. Topics include, but are not limited to, the following:

  • Optimization of traditional aeration technology and equipment;
  • The application of traditional aeration technology;
  • Optimization of micro–nano bubble formation process;
  • The growth and stability mechanism of micro–nano bubbles in water;
  • Degradation of contaminants or biofilm control in water purification systems or other systems;
  • The application of micro–nano bubble technology;
  • Similarities and differences between traditional aeration technology and micro–nano bubble technology.

Prof. Dr. Soon-Thiam Khu
Dr. Tianzhi Wang
Guest Editors

Manuscript Submission Information

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Keywords

  • micro–nano bubble
  • hydroxyl radical
  • advanced oxidation
  • biofilm
  • pollutant degradation
  • crop respiration

Published Papers (1 paper)

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Review

30 pages, 4807 KiB  
Review
Generation Mechanism of Hydroxyl Free Radicals in Micro–Nanobubbles Water and Its Prospect in Drinking Water
by Tianzhi Wang, Ci Yang, Peizhe Sun, Mingna Wang, Fawei Lin, Manuel Fiallos and Soon-Thiam Khu
Processes 2024, 12(4), 683; https://doi.org/10.3390/pr12040683 - 28 Mar 2024
Viewed by 735
Abstract
Micro–nanobubbles (MNBs) can generate ·OH in situ, which provides a new idea for the safe and efficient removal of pollutants in water supply systems. However, due to the difficulty in obtaining stable MNBs, the generation efficiency of ·OH is low, and the removal [...] Read more.
Micro–nanobubbles (MNBs) can generate ·OH in situ, which provides a new idea for the safe and efficient removal of pollutants in water supply systems. However, due to the difficulty in obtaining stable MNBs, the generation efficiency of ·OH is low, and the removal efficiency of pollutants cannot be guaranteed. This paper reviews the application research of MNB technology in water security from three aspects: the generation process of MNBs in water, the generation rule of ·OH during MNB collapse, and the control mechanisms of MNBs on pollutants and biofilms. We found that MNB generation methods are divided into chemical and mechanical (about 10 kinds) categories, and the instability of the bubble size restricts the application of MNB technology. The generation of ·OH by MNBs is affected by the pH, gas source, bubble size, temperature, and external stimulation. And the pH and external stimulus have more influence on ·OH generation in situ than the other factors. Adjusting the pH to alkaline or acidic conditions and selecting ozone or oxygen as the gas source can promote ·OH generation. MNB collapse also releases a large amount of energy, during which the temperature and pressure can reach 3000 K and 5 Gpa, respectively, making it efficient to remove ≈90% of pollutants (i.e., trichloroethylene, benzene, and chlorobenzene). The biofilm can also be removed by physical, chemical, and thermal effects. MNB technology also has great application potential in drinking water, which can be applied to improve water quality, optimize household water purifiers, and enhance the taste of bottled water. Under the premise of safety, after letting people of different ages taste water samples, we found that compared with ordinary drinking water, 85.7% of people think MNB water is softer, and 73.3% of people think MNB water is sweeter. This further proves that MNB water has a great prospect in drinking water applications. This review provides innovative theoretical support for solving the problem of drinking water safety. Full article
(This article belongs to the Special Issue Micro–Nano Bubble Technology and Its Applications)
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