NASCAP · Nanobubbles Stabilization for Cleaning Applications

Bulk nanobubbles (i.e. bubbles with a sub-micrometer size) are believed to have a diverse range of potential applications in fields such as: waste treatment, cleaning and purification technologies, biomedicine, food processing, drag reduction, sonoreactors and sonocatalysis. However, rigorous scientific evidence on how bulk nanobubbles (BNBs) may remain stably in solution is to date not existent. A number of methods for BNBs generation using mechanical, chemical or electrochemical approaches have been reported, but very few studies deal with confirming their gaseous nature. In nearly all research papers the size distribution of the BNBs is obtained from laser scattering, which can not discriminate bubbles form pollutant droplets or nanoparticles. That lead to considerable discussion on stabilized BNBs existence. Recently, we have shown that laser cavitation is a ''clean'' way to produce BNBs, while acoustic assisted bubble detection demonstrated the gaseous nature of the observed objects. That will constitute the main experimental strategy in the proposed project. The overall objective is to establish scientific basis for bulk nanobubbles research by providing conclusive answers to fundamental questions like: What is the underlying physical mechanics for which such small bubbles may remain stably suspended in liquids for long times?