Eliminación de contaminantes emergentes acuosos con redes metal orgánicas de tierras raras

In this research work, the study of the adsorption of some pharmaceutical contaminants considered "emerging contaminants" was reported. The adsorbent materials used were Ln₂MOF₃ that were synthesized with organic ligands BDC (terephthalic acid) and BDC-NH₂ (aminoterephthalic acid), while the metal centers were samarium, europium, terbium and dysprosium. The synthesis was carried out at room temperature and without any highly toxic solvent, since only water and ethanol were used. The physicochemical properties of Ln₂MOF₃ such as adsorption capacity, structure, functional groups, surface areas, morphologies, thermal stability and luminescent properties were analyzed using UV-Vis spectroscopy, DRX, FTIR, N₂ adsorption, SEM, TGA and photoluminescence spectroscopy. The CE retention processes were performed at concentrations of 100 ppm of each proposed drug (ibuprofen, naproxen, sulfamethoxazole and ciprofloxacin) with 0.2 g of Ln₂MOF₃. In addition, all the aforementioned physicochemical properties were compared after the adsorption of the CEs in order to determine the changes caused by the drugs in the Ln₂MOF₃. The amount of adsorbed CE of each of the MOFs was: 38.5, 19.2, 35.0 and 36.4 % for IBU, 34.6, 31.3, 43.2 and 50.2%, for NAP, 13.4, 17.8, 11.2 and 27.5% in the case of SMX and 32.6, 22.4, 27.2 and 30.8% for CIP and 30.8% in the MOFs: Sm₂BDC3, Eu₂BDC3, Tb₂BDC3, and Dy₂BDC3 respectively. The results of the BDC-NH₂ group showed values for NAP of 16.1, 16.3, 16.1 and 5.8%, the SMX adsorptions 26.4, 26.3, 26.4 and 13.5% and the CIP results were 20.8, 20.9, 20.7 and 4.2% for Sm₂(BDC-NH₂)₃, Eu₂(BDC-NH₂)₃, Tb₂(BDC-NH₂)₃ and Dy₂(BDC-NH₂)₃. The influence of the functional groups on the adsorption capacity and the dependence of the ionic radius of the lanthanides in these processes was determined by means of the techniques already mentioned above when analyzing the post-adsorption samples. Additionally, a chemical equilibrium study was performed where equilibrium constants were determined with the models: Freundlich, Langmuir, Temkin and Dubinin-Radushkevich for the CE adsorbed in the BDC MOF.