(2-Hydroxypropyl)-β-cyclodextrin regulated graphene quantum dots nanofiltration membranes with enhanced water permeability and high antibiotic rejection

Nanofiltration (NF) membranes are part of the promising technologies for treating antibiotic wastewater. However, current NF membranes are constrained by the trade-off between the water permeability and selectivity. To address this challenge, a (2-Hydroxypropyl)-β-cyclodextrin (OH-β-CD) incorporated into nitrogen-doped quantum dots (N-GQDs) aqueous phase to form the membrane (N-CD 0.1 ). The integration of the OH-β-CD manipulated the structural properties of selective layer and improved the water permeability. This was attributed to the fact that OH-β-CD not only provided an additional priority water channel, but also regulated the interfacial polymerization process of the membrane by slowing down the diffusion rate of N-GQDs. In addition, the hydrophilicity and electronegativity of the membrane were optimized by OH-β-CD. The results showed that the N-CD 0.1 membrane achieved a high antibiotic rejection (Ciprofloxacin: 98.28 %, Norfloxacin: 97.9 % and Ofloxacin: 97.46 %). The N-CD 0.1 membrane had a remarkable water permeability of 15.82 L⋅m −2 ⋅h −1 ⋅bar −1 , which was 2.05-fold that of the N-GQDs membrane. Furthermore, the N-CD 0.1 membrane exhibited good high-pressure stability. When the operating pressure was 3 ∼ 7 bar, the N-CD 0.1 membrane still had a high Ciprofloxacin rejection (> 97 %). Therefore, by the addition of OH-β-CD, the water permeability of NF membrane could be further improved almost without sacrificing the rejection of Ciprofloxacin, which provided a green and efficient strategy for the fabrication of high-performance NF membranes.