Controllable preparation of monodisperse nanobubbles by membrane sieving

Preparing monodisperse bulk nanobubbles with narrow size distributions is a prerequisite to study their size-dependent physical and chemical properties. Therefore, a facile membrane-based physical sieving method has been developed to make the bulk nanobubbles in targeting size. By changing the membrane texture and applying different filtration rates, the size distributions for the bulk nanobubbles can be purposely adjusted, where three types of filter membranes are used to intercept, crush or homogenize the nanobubbles through the physical sieving. The experimental results show that the membrane-based sieving can not only crush the large bubbles into smaller one but also fuse many small bubbles into a larger one, which is never reported before. We believe this work to provide a general method to obtain narrowly distributed nanobubbles from the as-generated polydisperse bulk nanobubbles.