Tunable Microbubble Generation via Adjustable Dual-Phase Venturi Sparger: A Pilot-Scale Study with Advanced BSD Analysis

Microbubbles are essential for enhancing gas–liquid contact and increasing interfacial area, improving separation efficiency in chemical, petrochemical, environmental, and mineral processes. This study systematically investigated factors impacting microbubble generation in a 5.5 m tall pilot-scale bubble column using an in-house designed adjustable dual-phase Venturi (ADPV) sparger. A multiclass dynamic gas disengagement (DGD) method, coupled with high-speed microimaging, was developed to determine column bubble size distributions (BSDs) under various conditions. Our results indicate that the sparger’s throat gap, gas-to-liquid (G/L) ratio, and surfactant concentration are dominant factors affecting microbubble generation, from the perspective of sparger geometry, hydrodynamics, and water chemistry. Smaller throat gaps, lower G/L ratios, or reduced surface tension facilitate the generation of smaller microbubbles and higher gas holdups. Compared to porous spargers, the ADPV sparger exhibited superior gas efficiency, offering an economical and scalable approach for generating tunable microbubble size distributions in pilot-scale systems.