Fabrication of magnetic cerium-organic framework-activated carbon composite for charged dye removal from aqueous solutions

The presence of synthetic dyes in water leads to health and ecological concerns due to their toxic and carcinogenic effects. For the remediation of coloured wastewater, we have fabricated a Ce-MOF@Fe₃O₄@activated carbon composite. The composite showed a ∼97–98% removal of indigo carmine and methylene blue at pH 7, whereas it was ∼83–85% for activated carbon. The adsorption and kinetic data followed the Temkin and Elovich models, respectively. Which suggested the involvement of physicochemical forces in the adsorption process. The thermodynamic study confirmed the adsorption process to be endothermic, where the adsorption performance improved with the increasing temperature. The increased intensity of the band at 824 cm⁻¹ (C–H) and 1004 cm⁻¹ (aromatic C[dbnd]C) in the Raman spectra confirmed the adsorption of dyes onto the adsorbent. Dye adsorption was further confirmed by the N 1s peak at 400 eV for C–N[dbnd]C in the dye-adsorbed composite. The shift in the binding energy of Fe 2p and Ce 3d peaks by 0.3–0.4 eV concluded the involvement of electrostatic and cation-π interactions in the adsorption process. A ∼90–98% dye removal capacity of the adsorbent even in the fourth cycle made it a highly stable and reusable adsorbent for remediation of coloured wastewater.