Metal-Organic frameworks and oxides derived from the preparation of an application in the adsorption of organic dyes
Metal-Organic Frameworks; Ca-MOF; CuMOF; CuO; Methylene blue; Adsorption; Degradation; discoloration
Metal-Organic Frameworks (MOF's) are a new class of porous structure materials in which atoms or metal clusters are coordinated by polydentate organic binders. They usually have high surface area and a large volume of pores, which makes them interesting alternatives for applications in catalysis, adsorption, separation, gas storage, among others. Calcium-based and 1,4-H2BDC acid networks were synthesized via a sonochemical method, whereas Cu-MOF's were prepared by electrochemical method from three different ligands, 1,3-H2BDC, 1,4-H2BDC and 5- NH2-H2BDC. The Cu-MOFs were calcined at a temperature of 923 K to obtain the mesoporous CuO. All the prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Ca-MOFs were tested in adsorption kinetics of the methylene blue adsorption, adsorption kinetics of the pseudo-first and pseudo-second order models, adsorption mechanism by the Freundlich and Langmuir models, study thermodynamic and reuse of the material. On the other hand, the mesoporous CuO was tested in the catalytic degradation of the methylene blue in the presence of H2O2. The Ca-MOFs presented maximum adsorption capacity of 58,520 μmol.g-1, a value compatible with other MOFs already reported in the literature. The most important result, however, was the high efficiency in the reuse, where 97% of the initial adsorption capacity was reached in the second cycle. Already in the degradation of the dye using mesoporous CuO as catalyst, a level of about 94% of discoloration was reached.