Research on Cleaning and Purification Using Fine Bubbles

Abstract

In recent years, it has been defined by the International Organization for Standardization (ISO) that fine bubble of 100 m or less be referred to as fine bubble. Fine bubbles will have specific properties different from bubbles that are seen in everyday life such as millimeter size and centimeter size by refining the gas. For example, the total surface area of a plurality of fine bubbles having the same volume as a single bubble of centimeter size is significantly large, and the chemical reaction, physical adsorption and mass transport at the gas-liquid interface are dramatically improved. Moreover, the fine bubbles have such property that dissolution efficiency of internal gas is improved from a huge total surface area acquired. In this study, cleaning and purification were performed utilizing the specific properties of these fine bubbles. In cleaning, the research was conducted on the removal of oils adhered to polypropylene and the removal of salt fixed to aluminum foil. Regarding the oil removal, the removal effect that relies on the total surface area of fine bubbles was verified. Regarding the removal of fixed salt, the result that by efficiency improvement of the removal of fixed salts is attained from phenomena such as fine bubble dissolution and bubble formation again. On the other hand, in the purification, fine bubbles were supplied to a river model tank containing the actual river sediment, and the changes in the water quality were investigated. As a result, the oxide layer of the sediment was formed from the high dissolution efficiency of the fine bubbles, and the suppression of elution of phosphorus from the sediment was verified.