Evaluation of the flotation efficiency of nano and microbubbles tailored to optimize bubble size distribution using a kinetic model

Bubble size is among the most important factors that determine flotation efficiency. The bubble used for flotation varies from nanobubbles (NBs) to microbubbles (MBs). In this study, the flotation experiments were carried out, and then the flotation efficiency was calculated based on the collision-attachment efficiency and the number of NBs and MBs bubbles using the kinetic model. The flotation efficiency was highest for tailored bubbles, followed by MBs and NBs. We determined that flotation efficiency increased as the interaction between the attachment ability of NB and the flotation ability of MB. We also determined the optimal mixing ratio by adjusting the amount of NB and MB to increase flotation efficiency. We found that the most important determinant of flotation efficiency was the ratio of MB and confirmed that NB acts as an auxiliary material that increases the attachment efficiency of floc and bubble. Also, when the amount of NB was too small flotation efficiency decreased, confirming that the flotation efficiency increased only when an appropriate ratio of NB was injected to increase the attachment efficiency.