Facile synthesis and characterization of Fe3O4@MgAl-LDH@STPOM nanocomposites for highly enhanced and selective degradation of methylene blue

Abstract

A novel layered and cauliflower-like Fe₃O₄@MgAl-LDH@Ce₃W₁₈ nanocomposite has been synthesized by the selective ion-exchange method. The nanocomposite contains sandwich-type polyoxometalate (STPOM) anion [(OCe)₃(PW₉O₃₄)₂]¹²⁻ intercalated Mg–Al layered double hydroxides (LDHs) coated on the surface of the Fe₃O₄ particles. The obtained nanocomposite was used as a catalyst for decomposition of methylene blue solution with the assistance of H₂O₂ at room temperature. To investigate the catalytic properties and efficiency of the nanocatalyst, a MgAl-LDH@Ce₃W₁₈ nanocomposite was also prepared. The physicochemical properties of the products were elucidated based on FTIR, SEM, TEM, EDS, TGA, XRD, VSM, and N₂ adsorption–desorption studies. The obtained results for Fe₃O₄@MgAl-LDH@Ce₃W₁₈ in the catalytic degradation of methylene blue (MB) dye, compared to other similar reported studies based on POMs and LDHs, represented a significant enhancement in the decomposition reaction rate owning to its high BET surface area and high charge density on selected STPOMs. The results indicated that the magnetic nanocatalyst has good selectivity toward methylene blue in the presence of rhodamine B (RB) and methyl orange (MO) with a high degradation efficiency of 90% within 5 minutes and excellent reusability in 6 cycles. Additionally, the magnetic nanocatalyst is readily separated and recycled from the reaction system by using an external magnetic field.