The novel MnCoFe2O4@PEG-4000 was synthesized by a simple and clean method. These nanoparticles have an almost spherical structure with an average diameter of about 21.95 nm, a satura- tion magnetization (Ms) of about 26.31 emu/g, and a thermal stability of about 100 °C. The application of these nanoparticles as a reusable green catalyst in the synthesis of hexahydroquinolines and benzo- pyrans and also as a nano-adsorbent for the removal of copper (II) (Cu (II)) and iron (III) (Fe (III)) metal ions in aqueous solutions was investigated. The use of a relatively green solvent, short reaction times, and high yield of products under optimal conditions are some of the advantages of these synthetic proce- dures for the preparation of hexahydroquinolines and benzopyrans in the presence of MCF@PEG-4000 MNPs as a catalyst. The adsorptive removal progress was optimized at pH = 7, the adsorbent dosage of 10 mg, and a contact time of 30 min. For the removal of
