The effect of a single loaded particle on bubble pinch-off dynamics in various liquids

Gas-liquid-solid multiphase flow refers to the simultaneous flow of gas, liquid, and solid phases in a system. This can occur in various industrial and natural processes, such as multiphase reactors, pneumatic conveying systems, and sediment transport in rivers and oceans. Gas-liquid-solid multiphase flow is commonly used in chemical and petrochemical industries for various processes, including fluidized bed reactors, catalytic cracking, and gas-solid reactors. Moreover, gas-liquid-solid multiphase flow is used in the production of oil and gas, including hydraulic fracturing and sand control operations. Furthermore, multiphase flow is important in environmental engineering applications, such as the transport of sediments in rivers and coastal areas as well as in biotechnology for fermentation and also used in the food and pharmaceutical industries for mixing and granulation processes. A boundary between two different phases, such as a liquid-gas or solid-liquid interface, that contains suspended particles or droplets is referred to as a particle-laden interface. These particles may come in a variety of shapes, sizes, and compositions, and their existence can have a big impact on how the interface behaves.

Although significant advancement has been achieved over the years, the impact of a single particle with millimeter size on pinch-off dynamics has not been documented and it could be of great significance in comprehending the precise mechanisms of particle influence on interfacial evolution and interaction. Understanding such knowledge will be vital in various applications such a biotechnology, aerosol science and microfluidics. It can also be used to research the properties of complex fluids such as foams and emulsions. A recent peer-reviewed paper published in the peer-reviewed Journal of Chemical Engineering Science, Professor Xiaofeng Jiang and colleagues from China University of Mining and Technology presented a novel experimental setup consisted of an observation groove, bubble generation system, image acquisition devices, and a light source. The main objective of this design was to enable the observation of the pinch-off and deformation stages of a particle-laden bubble. This study focused on bubble pinch-off dynamics. Previously, a cluster of nanoparticles was used at the gas-liquid-solid interface to investigate the pinch-off dynamics. Moreover, the authors focused on the effect of a single particle on bubble pinch-off dynamics. Pinch-off dynamics basically refers to the process by which a bubble separates itself from a liquid interface. It is a complex process that is governed by many factors such as surface tension, density of the fluid and viscosity and hence the need for the study arose.

The research team proposed a methodology that involved observing a specific area within the shooting range of a high-speed camera using a precise XYZ displacement adjuster to ensure experimental stability and reliability. To facilitate a detailed investigation, Newtonian and non-Newtonian fluids with different chemical concentrations were prepared. Carbomer solutions were stirred for over 12 hours to ensure the homogeneity. A spherical particle was positioned uniformly on the right side of the capillary with a short distance of approximately 0. Prior to bubble generation, the light source and high-speed camera were adjusted to capture clear images of both the capillary and particle.

The authors found that when a particle adheres to the neck of a bubble, the power-law exponent is between 0.60-0.67, which leads to hindered pinch-off. Conversely, when the particle adheres to the upper or bottom section of the bubble neck, the power-law exponent is between 0.40-0.50, which leads to accelerated pinch-off.

In conclusion, gas-liquid-solid multiphase flow has a wide range of applications in many different industries, making it an important area of study for researchers and engineers. Professor Xiaofeng Jiang and colleagues observed that the non-Newtonian fluid Carbomer aqueous solution with shear-thinning behavior can accelerate the pinch-off process for both pure bubbles and particle-laden bubbles. These results highlight the importance of the location of the particle attachment to the bubble neck, as well as the influence of fluid rheology on the pinch-off process. These findings can be used to improve the design and optimization of gas-liquid-solid multiphase flow systems such as bubble column reactors and froth flotation.