Microwave-assisted design of nanoporous graphene membrane for ultrafast and switchable organic solvent nanofiltration

Layered two-dimensional materials can potentially be utilized for organic solvent nanofiltration (OSN) membrane fabrication owing to their precise molecular sieving by the interlayer structure and excellent stability in harsh conditions. Nevertheless, the extensive tortuosity of nanochannels and bulky solvent molecules impede rapid permeability. Herein, nanoporous graphene (NG) with a high density of sp(2) carbon domain was synthesized via sequential thermal pore activation of graphene oxide (GO) and microwave-assisted reduction. Due to the smooth sp(2) carbon domain surfaces and dense nanopores, the microwave-treated nanoporous graphene membrane exhibited ultrafast organic solvent permeance (e.g., IPA: 2278 LMH/bar) with excellent stability under practical cross-flow conditions. Furthermore, the membrane molecular weight cut-off (MWCO) is switchable from 500 Da size of molecule to sub-nanometer-size molecules depending on the solvent type, and this switching occurs spontaneously with solvent change. These properties indicate feasibility of multiple (both binary and ternary) organic mixture separation using a single membrane. The nanochannel structure effect on solvent transport is also investigated using computation calculations. Layered 2D materials can be used for organic solvent nanofiltration (OSN) membrane fabrication due to precise molecular sieving by the interlayer structure and stability in harsh conditions. Here authors synthesise sp(2)-enriched nanoporous graphene by microwave treatment and demonstrate its excellent OSN performance.

Automated summary

Layered two-dimensional materials with interlayer structures can be used for organic solvent nanofiltration (OSN) membranes due to their precise molecular sieving ability and stability in harsh conditions. In this study, nanoporous graphene (NG) with a high density of sp(2) carbon domains was synthesized by microwave treatment and showed ultrafast organic solvent permeance and excellent stability. The membrane's molecular weight cut-off (MWCO) can be switched depending on the solvent type, allowing for the separation of multiple organic mixtures using a single membrane.