Microwave-assisted synthesis of nano Hf- and Zr-based metal-organic frameworks for enhancement of curcumin adsorption.

Hf- and Zr-based metal-organic frameworks are highly stable and porous materials that have been attracted in many applications, especially in biomedicine. The materials are commonly synthesized via solvothermal reaction between Hf or Zr salts and organic linkers, however this method requires elongated reaction time as well as results in heterogeneous particles and low yield, which leads to the difficulty for nano MOF synthesis. To overcome these disadvantages, we applied microwave method to enhance the synthetic efficiency and control particle homogeneity of nano UiO-66 framework. The nano MOFs, named Hf-UiO-66 and Zr-UiO-66, with highly homogeneous nanoparticles, very small sizes and high yields could be formed under microwave irradiation within a few minutes. According to the results from XRD, SEM, N 2 isotherm sorption, and TGA characterizations, the materials exhibited similar porosity and structure compared to the original framework. Additionally, Hf-UiO-66 and Zr-UiO-66 showed high efficiency for the treatment of curcumin's overdose by adsorbing the drug from aqueous solution with a maximum adsorption capacity up to 463.02 and 466.39 mg g−1, respectively, higher than reported Zr-UiO-66 (393.22 mg g−1). Moreover, the adsorption mechanisms were revealed that the adsorption of curcumin (CUR) by UiO-66 was influenced by defect sites in the MOF structure. UiO-66 (Hf and Zr) frameworks synthesized under microwave irradiation for curcumin adsorption. Image 1 • Microwave method is developed for effective and fast synthesis of nano metal-organic frameworks (named Hf- and Zr-UiO-66). • Particle sizes of these materials could be less than 50 nm. • The materials show higher efficiency for curcumin adsorption. • Kinetics and thermodynamics of curcumin adsorption on the MOFs were studied. • Adsorption mechanism was demonstrated by quantum mechanical calculations. [ABSTRACT FROM AUTHOR]