Performance of Rod-Shaped Ce Metal-Organic Frameworks for Defluoridation

The performance of a Ce(III)-4,4 ',4 ''-((1,3,5-triazine-2,4,6-triyl) tris (azanediyl)) tribenzoic acid-organic framework (Ce-H3TATAB-MOFs) for capturing excess fluoride in aqueous solutions and its subsequent defluoridation was investigated in depth. The optimal sorption capacity was obtained with a metal/organic ligand molar ratio of 1:1. The morphological characteristics, crystalline shape, functional groups, and pore structure of the material were analyzed via SEM, XRD, FTIR, XPS, and N-2 adsorption-desorption experiments, and the thermodynamics, kinetics, and adsorption mechanism were elucidated. The influence of pH and co-existing ions for defluoridation performance were also sought. The results show that Ce-H3TATAB-MOFs is a mesoporous material with good crystallinity, and that quasi-second kinetic and Langmuir models can describe the sorption kinetics and thermodynamics well, demonstrating that the entire sorption process is a monolayer-governed chemisorption. The Langmuir maximum sorption capacity was 129.7 mg g(-1) at 318 K (pH = 4). The adsorption mechanism involves ligand exchange, electrostatic interaction, and surface complexation. The best removal effect was reached at pH 4, and a removal effectiveness of 76.57% was obtained under strongly alkaline conditions (pH 10), indicating that the adsorbent has a wide range of applications. Ionic interference experiments showed that the presence of PO43- and H2PO4- in water have an inhibitory effect on defluoridation, whereas SO42-, Cl-, CO32-, and NO3- are conducive to the adsorption of fluoride due to the ionic effect.

Automated summary

The performance of Ce-H3TATAB-MOFs for fluoride removal was investigated in depth. The material exhibited good crystallinity and a mesoporous structure. The sorption process was found to be a monolayer-governed chemisorption. The presence of certain ions in water affected the defluoridation performance.