Confirmation and Quantification of Nanobubbles in Water Produced from a Batch Generator Driven by Electric Fields

Abstract

Nanobubbles, also known as ultrafine bubbles, are spherical gas pockets suspended in a liquid or attached to a solid substrate. The former is referred to as bulk nanobubbles, and the latter is termed as surface nanobubbles. Bulk nanobubbles are the focus of this study. Due to their smaller size, and large surface-to-volume ratio, they are remarkable in maintaining neutral buoyancy, and high mass transfer efficiencies. In this study, oxygen nanobubbles are created in water using a self-developed batch generator with the application of an electric field. Preliminary investigations of critical factors with this generator influencing nanobubble generation, such as wire arrangements, low-pressure headspace gas provision, and electric field intensities, are studied. Another focus of this study is to confirm the nanobubble existence using a sensitive speed of sound measurement, vibrating tube density (VTD) meter, and other sizing and counting techniques such as dynamic light scattering (DLS), nanoparticle tracking analyzer (NTA), and cryogenic scanning electron microscopy (Cryo-SEM).