posted on 2024-01-02, 15:34authored byZhigao Zhu, Minjie Song, Fangshu Qu, Yujun Zhou, Yue Yang, Junwen Qi, Jiansheng Li
Graphene
oxide (GO) membranes enabled by subnanosized diffusion
channels are promising to separate small species in membrane distillation
(MD). However, the challenge of effectively excluding small volatiles
in MD persists due to the severe swelling and subsequent increase
in GO interlamination spacing upon direct contact with the hot feed.
To address this issue, we implemented a design in which a polymer
is confined between the GO interlaminations, creating predominantly
2D nanochannels centered around 0.57 nm with an average membrane pore
size of 0.30 nm. Compared to the virginal GO membrane, the polymer-intercalated
GO membrane exhibits superior antiswelling performance, particularly
at a high feed temperature of 60 °C. Remarkably, the modified
membrane exhibited a high flux of approximately 52 L m–2 h–1 and rejection rates of about 100% for small
ions and 98% for volatile phenol, with a temperature difference of
40 °C. Molecular dynamics simulations suggest that the sieving
mechanisms for ions and volatiles are facilitated by the narrowed
nanochannels within the polymer network situated between the 2D nanochannels
of GO interlaminations. Concurrently, the unrestricted permeation
of water molecules through the multinanochannel GO membrane encourages
high-flux desalination of complex hypersaline wastewater.