Nanobubble-governed membrane with nanofluidic channels for efficient molecule/ion sieving

Abstract

Nanobubbles play key roles in determining various interfacial properties. However, investigation of water/ions transport behavior in nanobubble-governed nanofluidic channel was limited by the resolution of current in-situ observation techniques. Here, we investigated selective nanofluidic transport in nanobubble-plugged nanochannel during cross-flow forward osmosis (FO) process with a combined approach of simulations and experiments. Nanobubbles were generated by mechanical vibration during FO process. A nanobubble-plugged nanochannel model established via finite element modeling was used to explore nanobubble-governed selective water/ions transport. FO experimental results also verified nanobubble-plugged nanochannels with different asymmetric wettability and nanopore sizes could achieve unidirectional water transport while near-zero salt diffusion. Ion sieving tests further demonstrated nanobubble-plugged nanochannel could impede salt ions by nanobubble gating with size sieving, hydrophobic interaction and electrostatic interaction between nanobubbles and salt ions. These findings have implications for understanding selective nanofluidic transport in nanobubble-governed nanofluidic channel, which also provide new routes for designing potential osmosis membranes for high performance desalination.