Amine–carbon quantum dots (CQDs–NH₂) tailored polymeric loose nanofiltration membrane for precise molecular separation

Nanofiltration membranes show great potential in water treatment and resource recovery for their special separation mechanisms that can separate the small molecules effectively. However, their wide application needs to address the low separation efficiency caused by the similar solute sizes and charges while using the charged NF membranes with nanopores. This work reports a low-cost amine–carbon quantum dots (CQDs–NH₂) modified thin-film composite (CTFC) membrane via the facile interfacial polymerization process. The electrostatic force and competing reaction between the positively charged CQDs–NH₂ and the reactive monomers reformulated the interfacial polymerization process. The resultant CTFC membrane exhibits improved surface morphology and hydrophilicity. Besides, the incorporation of CQDs–NH₂ changed the original polyamide network structures to construct more transport space. The CTFC membrane permeance was boosted significantly (from 6.2 to 38.44 L m⁻² h⁻¹ bar⁻¹) compared with the unmodified TFC membrane, showing precise dyes separation property. This work may offer valuable guidance for the low-cost loose nanofiltration membrane preparation towards molecular separation.