Utilization of Ultrafine Gas Bubbles to Investigate the Jones–Ray Effect of Diluted Salt Solutions

The cause of the Jones–Ray effect has been controversially debated for years. Ultrafine gas bubbles were employed to lessen the surface excess of the surface-active impurities adsorbing to the air/water interface of the salt solutions, which would lead to a direct shift in surface tension observable by the Wilhelmy plate method. It was concluded in this study that once the surface excess of the inevitable impurities in the salts is lessened by the introduction of ultrafine gas bubbles, which possess great air/water interfacial area, the Jones–Ray effect becomes nonobservable. Therefore, our finding hypothesized that the Jones–Ray effect might not originate from salts.