Microbubbles for Effective Cleaning of Metal Surfaces Without Chemical Agents

Abstract

Traditional cleaning methods involving surfactants and ultrasound generate large amounts of wastewater. Microbubbles offer a more eco-friendly technology for interface cleaning. Here, we explored the efficiency of microbubbles for cleaning oil from metal surfaces. Air microbubbles at concentrations as high as 10 6 particles/mL were generated by hydrodynamic cavitation. Under optimal conditions, cleaning efficiencies for the removal of oil from carbon-steel and stainless-steel surfaces were 78.5 and 49.8% after 15 min, respectively, compared to only 6.5 and 9.9% without microbubbles. Additionally, combining microbubble treatment with the ultrasonic method achieved a higher efficiency than ultrasonic cleaning alone, achieving an efficiency of 85.5% after 3 min compared to 69.0%. The mechanism of microbubble cleaning was determined using a fluorescence observation system, and a model was established to describe the cleaning process. The use of microbubbles produced less emulsified oil wastewater because the oil that attaches to the microbubble surface floats with the bubbles to the surface of the cleaning water, where it can be removed, allowing for water recycling. This novel microbubble cleaning technology, which both enhances cleaning efficiency and reduces wastewater production, represents a viable and eco-friendly option for degreasing processes.

Exploring the Role of Nanobubbles in the Fate and Transport of Spilled Oil on Shorelines

“…The results showed that NBs facilitated the detachment of oil from the sand surface. Previous studies have suggested that hydrophobic NBs adsorb to the oil film and carry the oil away at the same time as it leaves the media surface . Furthermore, according to the Young–Laplace equation, the pressure of a bubble with a diameter of 1 μm is about 390 kPa, which is almost four times the atmospheric pressure .…”

“…A high mass transfer efficiency is expected for NBs by a faster dissolved air increasing rate and higher dissolved oxygen peak value. − Previous studies have shown that hydroxyl radicals are generated when bubbles collapse, which can enhance the oxidative capacity. , In addition, the negative zeta potential, rising velocity, high inertial pressure, and large gas–liquid interfacial area are also drivers of interest for NBs. Thus, NBs are currently employed in flotation, , surface cleaning, , irrigation, , water treatment, , soil remediation, , drug delivery, , oil recovery, and other fields.…”

Pretreatment with fine bubbles for effective zinc ion precipitation and removal from zinc electroplating wastewater

“…[ 25 ] In addition, after adsorbing on oil, MBs remove oil from the metal surface and float owing to the flotation property of bubbles. [ 26 ] This phenomenon provides higher removal efficiency of FBs than water rinsing.…”

“…[25] In addition, after adsorbing on oil, MBs remove oil from the metal surface and float owing to the flotation property of bubbles. [26] This phenomenon provides higher removal efficiency of FBs than water rinsing. The difference between the removal rates of the pressurized dissolution and cavitation instruments is attributed to the concentration of FBs.…”

Feasibility and efficacy of newly developed eco‐friendly, automatic washer for endoscope using electrolyzed alkaline and acidic water

“…There are also concerns regarding the impact of residual washing agents on the human body and on medical devices. 13 In addition, precision instruments such as endoscopes cannot withstand heat or strong chemicals, which makes it difficult to efficiently remove biofilms and special proteins such as prions. 14 Automated, effective, and atraumatic washing methods are therefore crucial for precision instruments; however, few studies have examined these aspects in detail.…”