Preparation and characterization of microbubbles with a porous ceramic membrane

The efficient preparation of microbubbles is very meaningful due to the wide applications of microbubbles in water treatment, food industry, cosmetics, and pharmaceuticals industry. In this work, a flow system based on commercial porous ceramic membrane is developed for controllable generation and rapid characterization of microbubbles. The images of generated microbubbles in the visualization cell are captured by a CCD on the microscope, and the size and distribution of microbubbles can be rapidly obtained with MATLAB. The influences of liquid flow velocity, liquid viscosity, surface tension, membrane pore size and gas superficial velocity on the microbubble size are systematically studied. To increase the liquid flow velocity and corresponding liquid shear stress, a stainless-steel rod is inserted into the middle of ceramic membrane, which can effectively decrease the bubble size. Under the optimal experimental conditions, the microbubbles with the diameter of 64∼87 μm are continuously prepared. A mathematical model is developed which can predict the microbubbles size under different conditions, which is useful for the understanding and design of microbubble generation.