Zr-MOF-glutaraldehyde-Adn@Fe3O4 nanocomposite: as a new adsorbent for removal of methylene blue and heterogeneous nanocatalyst for the synthesis of tetrahydrobenzo[b]pyran derivatives

In this research, a magnetic hybrid material (Zr-MOF-glutaraldehyde-Adn@Fe₃O₄) consisting of UiO-66-NH₂ as a stable and unique metal-organic framework, and Fe₃O₄ nanoparticles was synthesized. Firstly, a highly stable zirconium-based UiO-66-NH₂ metal-organic framework (Zr-MOF) was modified with glutaraldehyde and subsequently with the green ligand of adenosine (And) to introduce functional groups containing N and O atoms on the surface. Secondly, Fe₃O₄ nanoparticles were successfully stabilized into functionalized MOF named Zr-MOF-glutaraldehyde-Adn to form Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ nanocomposite. Vibrating sample magnetometer (VSM) analysis disclosed a saturation magnetization of Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ was acquired to be 34.76 emu/g, clearly indicates to good magnetic properties of prepared nanocomposite. The performance of Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ nanocomposite as a new adsorbent in the adsorption of methylene blue (MB) and a heterogeneous catalyst in the synthesis of tetrahydrobenzo [b]pyrans derivatives was evaluated. In the removal process of MB dye, the optimization parameters related to the initial pH (3-9), quantity of adsorbent (5-20 mg), initial concentration of analyte (10-40 mg/L), and contact time (2-20 min) of the solution were defined, and tests related to equilibrium isotherms and adsorption kinetics were investigated. The Langmuir isotherm (R² = 0.99) and pseudo-second-order kinetics model (R² = 0.99) exhibited well interpretation of the adsorption experiment outcomes. The results indicated that the maximum capacity adsorption of MB using Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ was 62.5 mg/g. In addition, Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ demonstrated excellent efficiency in the synthesis of substituted tetrahydrobenzo [b]pyrans scaffolds in H₂O as a safe, available, and ideal solvent. The great adsorptive performance, using green solvent, short reaction time, high conversion, and reusability of the catalyst are some of the notable features of the proposed multifunctional nanocomposite. The novelty of the current research relies on the development and exploration of the multi-application of the designed Zr-MOF-glutaraldehyde-Adn@Fe₃O₄ nanocomposite as an efficient sorbent for the easy purification of wastewater and a heterogeneous catalyst towards the synthesis of tetrahydrobenzo [b]pyrans derivatives.