The present invention is directed to nanofiltration (NF) composite membranes comprising at least one polymeric porous substrate layer (S) and at least one porous selfassembled supramolecular membrane layer (F); a method of preparing such composite membranes; method of separation/filtration/purification of heavy metal cations, inorganic anions, and organic small molecules by applying such composite membranes; as well as filter cartridges and filtration devices comprising said composite membranes.