Influence of Influent Properties on Microbubble Size in Pressurized Dissolution-Based Generation Methods

Abstract

Microbubbles, due to their smaller size, possess distinctive physicochemical properties that enhance performance and efficiency across various industrial applications. The pressurized dissolution method is widely used for microbubble generation due to its ability to produce high concentrations of small bubbles. Many industrial processes use microbubbles under varying temperature and pH conditions to optimize process performance. However, the effects of these parameters on the size of microbubbles have not been systematically studied. This study comprehensively investigates the influence of discharge pressure drop, temperature, and pH on the size of microbubbles generated by the pressurized dissolution method. A phase Doppler anemometry (PDA) system was used for microbubble characterization. We found that the normalized arithmetic mean diameter (d₁₀*) follows a power-law relationship with normalized discharge pressure drop (ΔP*). The power law index is influenced by temperature and pH levels. A multilinear regression model was developed to establish a significant correlation between the power law index and these factors, which notably affect microbubble size. The model revealed negative correlations between the power law index and both temperature and pH. Furthermore, the normalized Sauter mean diameter (d₃₂*) also follows a power law relationship with ΔP*. However, the power law index for d₃₂ is consistently smaller than the corresponding power law index for the arithmetic mean diameter as d₃₂ is largely weighted by the larger size of bubbles. These findings provide valuable insights into controlling the size of microbubbles, which potentially enhance process performance and efficiency across industries operating under various temperature and pH conditions.