Synthesis of MOF@COF composites and study on dye adsorption properties

MOF@COF hybrid materials not only have high stability and adjustable function, but also have the characteristics of MOFs and COFs materials, which make them have important application value in the field of adsorption. This article employs 1,3,5-benzene tricarbonyl chloride and p -Phenylenediamine as covalent organic framework monomers. Through the in-situ growth of covalent organic frameworks (COF) on the surface of NH 2 -MIL-88(Fe) material, a novel, stable, and porous COF-on-MOF hybrid material (NH 2 -MIL-88(Fe)/COF) was synthesized. The structure, morphology, and performance of the hybrid material were thoroughly examined using characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Subsequently, We explored the MOF@COF hybrid material as an effective adsorbent for removing organic dyes, namely methylene blue (MB), methyl orange (MO), and crystal violet (CV). The influence of various adsorption parameters, such as adsorption time, initial dye concentration, and different pH values, on dye adsorption performance was systematically investigated. Experimental results revealed that at pH = 7, NH 2 -MIL-88(Fe)/COF demonstrates maximum adsorption capacities of 114 mg·g −1 , 106 mg·g −1 , and 102 mg·g −1 for methylene blue, methyl orange, and crystal violet, respectively. The adsorption process follows pseudo-second-order kinetics and Langmuir isotherm models. Lastly, NH 2 -MIL-88(Fe)/COF maintains high removal efficiency for the three dyes even after five repeated uses, establishing it as a stable and efficient adsorbent. The research findings suggest that MOF@COF hybrid materials hold promising applications in the treatment of dye-containing wastewater.