Synthesis of the magnetic core–shell bi‐metallic and tri‐metallic metal–organic framework nanocomposites for dye adsorption

Bi‐metallic and tri‐metallic metal–organic frameworks (MOFs) supported on the magnetic activated carbon (MAC) were synthesized for the reduction of methylene blue (MB) concentration in the aqueous solutions. The adsorbent nanocomposites were characterized by applying the general tests including XRD, FTIR, FESEM, TEM, BET, and VSM. The XRD achievements demonstrated that crystalline structure of MOFs was derived on the MAC by the presented method. The core–shell morphology with nano‐scale size of the magnetic carbonaceous MOFs was detected in TEM and FESEM micro‐images. The acceptable magnetic strength of the prepared adsorbents was proved by using the VSM analysis. The important operating conditions including pH and temperature were also evaluated, while the other parameters were kept constant. The pseudo‐second‐order kinetic model was matched with the experimental data to show the kinetic behavior of the multi‐component MOFs. The isotherm studies showed that the good agreement between the experimental data with both Langmuir model and the maximum capacities was calculated to be about 66.51 and 71.43 mg/g for the bi‐metallic and tri‐metallic nanocomposites, respectively. Regeneration experiments indicated that the fabricated adsorbents have an excellent reusing adsorption capacity which can be a proper selection for the industrial applications. Practitioner points Bi‐metallic and tri‐metallic MOFs supported on the magnetic activated carbon were synthesized by the facile preparation method. Adsorption of methylene blue by using MOFs were successfully done. Nanocomposites were evaluated by XRD, FTIR, BET, FESEM, TEM, and VSM techniques. Maximum of adsorption capacity was observed for tri‐metallic MOF as 71.43 mg/g. Magnetic MOF.