Hyperlooping carbon nanotube-graphene oxide nanoarchitectonics as membranes for ultrafast organic solvent nanofiltration

Abstract

Membrane technology is a key enabler for a circular pharmaceutical industry, but chemically resistant polymeric membranes for organic solvent nanofiltration (OSN) often suffer from lower-than-required performances. Recently, graphene-based laminated membranes using small-flake graphene oxide (SFGO) nanosheets open up new avenues for high-performance OSN, but their permeance toward high viscosity solvents is below expectation. To address this issue, we design hyperlooping channels using multiwalled carbon nanotubes (MWCNTs) intercalated within lanthanum(III) (La3+)-cross-linked SFGO nanochannels to form a ternary nanoarchitecture for low-resistant transport toward high viscosity solvents. At optimized MWCNT loading, the defect-free membrane exhibits 138 L m-2 h-1 bar-1 ethanol permeance at >99% rejections toward organic dyes, outperforming state-of-the-art graphene oxide (GO)-based membranes to date. Even butanol─with twice the viscosity of ethanol─exhibits a permeance no less than 60 L m-2 h-1 bar-1 at comparable rejection rates. Theoretical simulation suggests that La3+ cross-linking is critical and can create an intact architecture that brings size exclusion into play as the dominant separation mechanism. Also, MWCNT nanochannel offers at least 1.5-fold lower ethanol transport resistance than that of the GO nanochannel, owing to greater bulk freedom in orientating ethanol molecules. Overall, the hyperlooping architecture demonstrates ∼3-fold higher permeance than neat SFGO membrane for elevating OSN performances.