Assessment of sub-200-nm nanobubbles with ultra-high stability in water

Abstract

AbstractBubble technology has proven to be an efficient technique of reducing environmental pollution, strengthening water treatment procedures, and increasing production in industrial and agricultural applications. Compared to large bubbles such as macro- or micro-bubbles, nanobubbles (NBs) in liquids have several intriguing properties, including low buoyancy, high mass transfer efficiency, and high reactivity. In particular, NBs smaller than 200 nm are unexpectedly stable. However, determining the underlying mechanism of the stability of NBs in a solution is difficult. Most studies only focus on the temporal changes in the size and surface charge of NBs; the changes in the concentration of NBs are typically ignored. In this study, we investigate the number and stability of high-concentration NBs under various conditions. The results show that the number and concentration of NBs can be maintained at approximately 80–90% under various conditions, such as aging, temperature, centrifugation, shaking, and stirring. In other words, NBs possess significant potential for use in mass production and distribution in bubble technologies.