Review on thin-film nanocomposite membranes with various quantum dots for water treatments

This review addresses water treatment using thin-film nanocomposite (TFN) membranes incorporated with various quantum dots (QDs), focusing heavily on dye removal and membrane antifouling. QDs are zero-dimensional nanomaterials that have been incorporated into the selective layer or support layer of nanofiltration (NF) membranes to increase membrane permeance while retaining high selectivity. Various preparation methods, including interfacial polymerization (IP), nonsolvent-induced phase separation (NIPS), vacuum filtration, layer-by-layer (LbL), and spin coating, are discussed with their advantages and disadvantages. Carbon-based QDs, including graphene quantum dots (GQDs), graphene oxide quantum dots (GOQDs), and carbon quantum dots (CQDs), have high hydrophilicity and excellent functionalizability, which enable fine control over porosity, thickness, repulsiveness, wettability, and fouling resistance. The low dimensionality of QDs also endows membranes with excellent anti-biofouling properties through oxidative stress and abundant edge contacts at the liquid/membrane interface. Some carbon-based QDs and metal QDs also enable photocatalytic dye degradation for enhanced water purification.