Bifunctional superwetting carbon nanotubes/cellulose composite membrane for solar desalination and oily seawater purification

Simultaneous removal of oil and ions from complex oily seawater to produce fresh water remains a serious challenge, and more effective and sustainable alternatives need to be developed. Here, by adjusting the com-ponents of dialdehyde microcrystalline cellulose (DAC) and amino modified multi-walled carbon nanotubes (CNTs), a bifunctional composite membrane (CNT@DAC) enabling solar-driven desalination and emulsion fil-trating separation was prepared. CNTs cross-linked on the DAC membrane through Schiff base reaction and vacuum-assisted filtration had excellent light-harvesting effects, and could provide a superior light absorption of up to 97% in the full solar spectrum. And a new stacking strategy was proposed to build 2D water path and reduce heat loss, so that the solar-driven evaporation efficiency of the CNT@DAC membrane could reach 90.86% under 1.0 sun. Noteworthily, the CNT@DAC membrane with underwater superoleophobic and underoil super-hydrophobic achieved on-demand efficient separation of oil-in-water and water-in-oil emulsions. With the help of this bifunctional membrane, the integrated purification of oily seawater was realized, thereby obtaining clean water resources that meet drinking water standards. We believe that this research represents an avenue for boosting the combination of solar-driven water evaporation and superwetting systems into practical applications, and will attribute to solve the water and energy crisis.

Automated summary

By adjusting the components of DAC and CNTs, a bifunctional composite membrane capable of solar-driven desalination and emulsion filtering separation was prepared. This membrane exhibits excellent light absorption and high solar-driven evaporation efficiency, enabling the integrated purification of oily seawater and providing clean water resources that meet drinking water standards.