Preparation and Characterization of Functionalized Metal-Organic Frameworks with Core/Shell Magnetic Particles (Fe3O4@SiO2@MOFs) for Removal of Congo Red and Methylene Blue from Water Solution

In this work, a novel core@double-shell three layer structure adsorbent (Fe3O4@SiO2@Zn-TDPAT) [TDPAT = 2,4,6-tris(3,5-dicarboxyl phenylamino)-1,3,5-triazine] was prepared to remove congo red (CR) and methylene blue (MB). The as-obtained magnetic adsorbent Fe3O4@SiO2@Zn-TDPAT was characterized by X-ray diffraction, Fourier transform infrared spectra, vibrating sample magnetometry, transmission electron microscopy, and scanning electron microscopy. The influencing adsorption parameters including adsorbent amounts, extraction time, pH, and ionic strength were investigated. Under the optimized conditions, the removal efficiencies of CR and MB reached 100 and 99%, respectively. The pseudo-second-order kinetic model and Langmuir model were suitable to illustrate the adsorption processes of CR and MB. The thermodynamic values, including Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees), showed that the adsorption processes were spontaneous and endothermic in nature. Moreover, the obtained nanocomposite remained stable in different acid-alkaline solutions and exhibited good reusability after multiple cycles. All of the experimental results indicated that Fe3O4@SiO2@Zn-TDPAT could be a potential adsorbent to purify dye wastewater.