STUDIES
Cleaning
Disinfection applications of ozone micro- and nanobubbles
Micro- and nanobubbles (MNBs) are tiny gas-filled bubbles with diameters less than 100 μm (microscale) and even smaller than 1 μm (nanoscale). They are notable for their extended stability in water and an increased surface area due to their size, which enhances their interactions in various processes. Ozone micro- and nanobubbles (OMNBs) have attracted attention in disinfection applications, as they leverage ozone’s high oxidizing potential and the MNBs’ longevity to improve disinfection effectiveness and extend ozone’s active duration. This critical review consolidates recent studies on OMNBs, highlighting the potential of these bubbles in disinfecting drinking water, as well as in aquaculture, agriculture, and wastewater treatment. Key aspects covered include MNBs’ properties, generation techniques, and methods for characterizing their size and quantity. Additionally, research gaps, limitations, and recommendations for future studies are discussed to further advance this promising technology
Surface Cleaning of Oil Contaminants Using Bulk Nanobubbles
This study demonstrates that bulk nanobubble water effectively removes oil contaminants from surfaces like glass and porcelain without the need for surfactants or abrasion, which can harm the environment and materials. Nanobubble water detached oil microdroplets from both hydrophobic and hydrophilic surfaces, simulating conditions found in dishwashers and washing machines. Unlike traditional cleaning solutions, nanobubble water achieved successful oil removal, making it a cost-effective, eco-friendly alternative with promising applications for surface cleaning.
Toward the eco-friendly cosmetic cleansing assisted by the micro-bubbly jet
To reduce skin irritation and environmental impact from chemical cosmetic cleansers, this study proposes a microbubble-laden water jet as an alternative for cleansing without or with fewer chemicals. A specially designed nozzle produced a bubble-rich jet that effectively removed adhesive cosmetics, such as foundation and lip tint, from synthetic surfaces, outperforming a standard liquid jet. Enhanced cleaning is attributed to the increased kinetic energy of the liquid-air mixture and direct bubble-cosmetic collisions. This method shows promise for developing eco-friendly cosmetic cleansing solutions suitable for sensitive skin.
Detergent waste poses severe environmental risks due to toxic components like anionic surfactants, phosphate compounds, bleach, and fragrances, which destabilize ecosystems. A sustainable alternative is the use of ultrafine bubbles in cleaning processes. These bubbles, with a negative charge, attract positively charged particles, providing effective cleaning through mechanisms like degreasing, sloughing deposits, and releasing shock waves upon bursting. Ozonized ultrafine bubbles, in particular, exhibit strong detergency, penetrating and separating oils from surfaces and reaching tight spaces. As they merge into larger ozonized microbubbles, they act as wedges to help dislodge adhered particles, making them highly effective in environmentally friendly cleaning applications.
Remediation of diesel-oil contaminated soils using an innovative nanobubble and electrolyzed catalytic system
An electrolyzed catalytic system (ECS) has been developed to produce nanobubble-enriched catalytic water (NECW) for effective soil and groundwater remediation from diesel oil contamination. Key findings include:
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NECW, created with titanium electrodes and iron-copper hybrid oxide catalysts, contains high concentrations of oxidizing free radicals and stable nanobubbles.
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Adding electrolytes (NaCl or Kâ‚‚SOâ‚„) enhances radical production, while nanobubble bursting generates radicals to sustain oxidation processes.
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NECW achieved a 72.4% reduction in soil petroleum hydrocarbons and complete removal in water, using desorption and extended oxidation.
NECW’s high oxidizing potential, radical concentration, and stable nanobubbles make it an efficient, eco-friendly solution for hydrocarbon-polluted environments, reducing secondary pollution risks.
Micro–nanobubbles (MNBs) provide a novel and efficient way to remove pollutants in water systems through the in situ generation of hydroxyl radicals (·OH). While MNBs have great potential, stability issues currently limit their pollutant removal efficiency. This review explores MNB applications for water safety, covering MNB generation, OH production during bubble collapse, and pollutant control mechanisms. Chemical and mechanical methods exist to generate MNBs, but factors like pH, gas source, bubble size, and temperature significantly impact ·OH yield. High-energy collapse of MNBs can reach 3000 K and 5 GPa, achieving up to 90% pollutant removal for substances like trichloroethylene and benzene.
MNBs also show potential in drinking water treatment, improving taste and quality. Tests found 85.7% of people rated MNB-treated water as "softer" and 73.3% as "sweeter" compared to regular water. This review highlights MNBs' promise for safe, effective water purification and taste enhancement, contributing to future water safety solutions.