Janus mesoporous wood-based membrane for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination

Directional transport of liquid is crucial for many applications including seawater desalination, oil/water separation, fog collection, membrane distillation and so forth. Particularly, Janus wood membranes, with asymmetric special wetting property on two sides, and mechanically robust bio-based substrate with ample pores and open nano-/micro-channels, present enticing opportunities to address this challenge. In this study, we report a Janus mesoporous wood-based membrane demonstrating the capabilities for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination. Thanks to the inner driving force arising from the asymmetric special wettability, unique wood microchannels for the transpiration of trees, and the synergistic effect of PPy and Ag/AgCl NPs anchored to wood matrix, Janus mesoporous wood-based membrane would promote the desired transport without any external energy input for high-efficiency seawater desalination and switchable oil/water separation. Meanwhile, the aromatic dyes and other organic compounds in industrial wastewater or polluted seawater would get more opportunities to contact with the anchored Ag/AgCl NPs during flowing through the wood microchannels. Above advantages endow the Janus mesoporous wood-based membrane with excellent pollutant degradation efficiency (MB: 86.4 %, RhB: 91.9 %), high solar conversion efficiency (95.33 %), outstanding separation efficiency towards oil-in-water emulsion (∼99.51 %), remarkable oil adsorption capacity (∼8 times of its own weight), and great antibacterial efficiencies (E. coli: 99.87 %, S. aureus: 99.78 %, B. subtilis: 99.96 %). Results also show that this Janus mesoporous wood-based membrane has the satisfactory resistance to acid and base, robust mechanical structure, good recycling stability, high salinity tolerance and remarkable self-desalting capability. This study represents a new avenue for fabrication and design of Janus wood-based photothermal materials, and certainly will contribute to alleviating the global water and energy shortage issue.