Environment-friendly surface cleaning using micro-nano bubbles

Cleaning a surface using a solution containing a large number of micro to nano scale bubbles has significant advantage regarding environmental protection. This review first briefly introduces the cleaning mechanism of micro-nano bubbles (MNBs), including physical and chemical effects. Then the applications of MNBs in cleaning of metal parts, precision parts, cultural relics or food are introduced. After that, coupled cleaning method of ultrasound and bubbles is introduced. Finally, the characterization methods for the cleaning effect are introduced, which mainly focuses on the changes of physico-chemical properties (mass or cleaning area, infiltration, colony number and light scattering intensity) of the cleaned parts or that (like conductivity) of the solvent. It is believed that MNBs technology will be applied in a broader range of surface cleaning applications.