Water/gas separation based on the selective bubble-passage effect of underwater superaerophobic and superaerophilic meshes processed by a femtosecond laser.

To solve the problems caused by tiny bubbles in liquids and the difficulties involved in collecting useful gas underwater, this paper proposes a method to separate bubbles from water by integrating underwater superaerophobic and superaerophilic porous membranes, including bubble removal and collection methods. Inspired by fish scales and lotus leaves, underwater superaerophobic microstructures and underwater superaerophilic microstructures are prepared on a stainless steel (SS) mesh by femtosecond laser processing, respectively. The as-prepared underwater superaerophobic mesh has an anti-bubble ability, while the underwater superaerophilic mesh has a bubble-absorption ability in water. Based on the different dynamic behavior of bubbles on these two kinds of superwetting meshes, efficient water/bubble separation is achieved by using laser-induced superwetting meshes. Tiny bubbles can be completely removed from the water flow in a pipe or easily collected. Such water/gas separation methods based on underwater superaerophobic and superaerophilic porous membranes provide an effective way to prevent the damage caused by bubbles and to collect the available gas in liquids, which has great potential applications in energy utilization, environmental protection, medical and health care, microfluidic chips, chemical manufacturing, agricultural breeding, and so on.