A copper-based porphyrin metal-organic framework for efficient removal of methylene blue

Metal-organic frameworks (MOFs) have become a prevalent class of adsorbent materials due to their high porosity, large specific surface area, tunable structure and functionality, good stability, and high adsorption capacity. Herein, a copper-based porphyrin metal-organic framework (MOF), designated as CZJ-6, was synthesized and applied to adsorb the aqueous pollutant methylene blue. Characterizations of the material were performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), 1 H NMR spectra, powder X-ray diffraction (PXRD), and Fourier transform infrared spectra (FT-IR). Concurrently, energy-dispersive X-ray spectra (EDS) and XPS analyses confirmed the successful adsorption of methylene blue (MB). Adsorption experimental results demonstrate that the adsorption kinetics obeyed a pseudo-second-order model, while the adsorption thermodynamics followed the Langmuir isotherm. A maximum adsorption capacity of 780.94 mg g -1 at 50° was achieved. In addition, the adsorption thermodynamic data suggest that the adsorption process is endothermic. The removal of MB can be attributed to electrostatic attraction, physical adsorption, and surface complexation, with chemical adsorption via surface complexation being particularly significant.