Degreasing of Solid Surfaces by Microbubble Cleaning

Abstract

It is increasingly required to reduce the environmental impact and cost in the field of industrial cleaning. As a substitute for conventional degreasing technology using organic solvents, acids, and alkalis, the authors have developed a new cleaning technology that uses microbubbles having an average diameter of about 70 µm. Grease being adsorbed onto a bubble's surface and grease being separated from a solid surface by its buoyancy were captured using a high-speed microscopic video camera to demonstrate the degreasing capability of bubbles. High-density microbubbles were generated by adding a trace amount of a specific chemical (0.1% weight or less). The cleaning performance using microbubbles was found to be highly improved compared with that using normal bubbles. It was also revealed that the grease removal efficiency was strongly dependent on the viscosity of the grease. Raising the temperature of the cleaning solution is an effective method of improving cleaning performance by reducing the viscosity. Finally, the degreasing of about 150 machining metal parts at the same time was demonstrated to exceed the common target cleaning level (5–20 µg/cm2) in only 2 min because of their large surface area. Furthermore, the high degreasing performance was maintained even after repeated use of the cleaning solution because of the separation of grease due to buoyancy.

Study on oral hygiene by nanobubbles from high-density nozzle

“…The application of this device is pervasive, and its key factor is the water flow outside the nozzle’s water hole outlet 13, 14, 33 . Miyamoto et al 20 performed a study on using micro-bubbles with an average diameter of 70 micrometers to remove oil residues on surfaces, which had higher cleaning action than normal bubbles; if combined with detergent with micro-bubbles, this can make absorption of detergent around bubbles more effective, and, therefore, the cleaning effect is more significant. For these applications, a higher separation frequency generates smaller microbubbles and the cross-flow of fluid injected into the gas results in a higher separation speed and generates smaller bubbles 6, 16 .…”

The Application Method of Nanobubble Conveyor on the Effect of Preventive Oral Hygiene

“…(1) Cleaning action: the detergent solution is absorbed around the bubbles to increase the contact surface areas between the detergent and dirt, which improves the cleaning action. Miyamoto performed a study on using microbubbles with an average diameter of 70 micrometers to remove oil residues on surfaces, which had higher cleaning action than normal bubbles; if combined detergent with microbubbles can make detergent be absorbed around bubbles, the cleaning effect is more significant [20]. (2) Sterilization: the sterilization action of ozone can be improved by forming microbubbles and can enhance the sterilization effect; lkeura has used water with ozone microbubbles to remove pesticide residues and pests from vegetables and fruits [21].…”

Generation of Monodisperse Microbubbles with a Controlled Size of Less Than 10 µm at a Generation Rate on the Order of 10⁵ Bubbles/s in Glass Capillary Microfluidic Devices

“…Microbubbles, which are bubbles with diameters on the order of micrometers, have been used in various elds, such as food processing (Campbell and Mougeot, 1999;Zúñiga and Aguilera, 2008;Rovers et al, 2016), wastewater treatment (Chu et al, 2008;Zhang et al, 2018), washing (Miyamoto et al, 2007;Ikeura et al, 2013;Iizuka et al, 2016), and materials science (Makuta et al, 2012;Wan and Stone, 2012;Chen et al, 2013;Brugarolas et al, 2014;Katayose et al, 2018). In recent years, microbubbles have also attracted attention regarding their potential applications in the medical eld (Lindner, 2004;Liu et al, 2006;Yoon et al, 2014).…”