2D lamellar membrane with MXene hetero-intercalated small sized graphene oxide for harsh environmental wastewater treatment

Efficient wastewater treatment under harsh conditions remains a great challenge, while traditional filtration membranes are inefficient to meet the demands due to its poor chemical resistance as well as the “trade-off” effect between high permeability and selectivity. Herein, a chemical-resistant 2D lamellar membrane simultaneously with high flux and rejection for harsh environmental wastewater treatment was proposed, via assembled small sized graphene oxide nanosheets (NGO) layer-by-layer on polyphenylene sulfide (PPS) while hetero-intercalated with MXene. As the performance of 2D laminated membranes is determined by the length/tortuosity of transport channels and interlayer spacing between the flakes, NGO nanosheets were sonicated into small sizes (<500 nm) and intercalated with MXene to engineer shorter/less tortuous transport pathways while tuning the interlayer spacing for fast and selective separation. The membranes exhibit remarkably high-water permeability (up to 136.68 L·m−2·h−1·bar−1) while simultaneously with excellent retention (>99.99 %) for various dyes (molecular weight 288.77–1017.65) at the NGO/MXene ratio of 1/7, which is much higher than most reported membranes. Meanwhile, the Ti-O-C covalent bonding between NGO and MXene nanosheets also enables stable ultrafast water transmission and anti-swelling stability. The PPS-NGO/MXene membranes could still exhibit excellent separation performance even under various harsh environments (strong acids, bases, high pressures, high temperatures, bacteria, organic solvents), which holds great promise for sustainable wastewater treatment under harsh conditions.