Nanocellulose Crystal-Enhanced Hybrid Membrane for CO2 Capture

Developing a membrane material with both high CO2 permeability and high CO2/N-2 selectivity is always desired for CO2 capture, while improving the sustainability of the membrane preparation process is of equal importance. In the current work, a nanocellulose crystal (CNC) was blended with hydrophilic Pebax 1657 for CO2 separation application. The CO2/N-2 separation performance of Pebax 1657/CNC hybrid membranes with up to 40 wt % CNC was evaluated by mixed-gas permeation tests under both dry and humid conditions. The humid test condition simultaneously increases CO2 permeability and CO2/N-2 selectivity of all CNC/Pebax hybrid membranes compared to those under dry conditions. Introduction of only 5 wt % CNC into Pebax 1657 realizes 42 and 18% increments in CO2 permeability (305.7 Barrer) and CO2/N-2 selectivity (41.6), respectively. However, further increasing the CNC loading increases the tortuosity of the membrane and results in the self-assembly of CNC in the Pebax matrix, which is observed by SEM, thus leading to both reduced gas permeability and CO2/N-2 selectivity. The CO2/N-2 separation results of 5 wt % CNC/Pebax locate close to Upper Bound 2008, showing its potential as a CO2/N-2 separation membrane material.