Hierarchical camellia-like metal-organic frameworks via a bimetal competitive coordination combined with alkaline-assisted strategy for boosting selective fluoride removal from brick tea

Developing an efficient and easy scale-up adsorbent with excellent fluoride adsorption and selectivity from brick tea is urgently desired. However, the separation of fluoride from tea is particularly challenging due to it contains abundant active compounds. Herein, we report ultrahigh fluoride adsorption from brick tea by a hierarchical camellia-like bimetallic metal-organic frameworks (MOFs). The hierarchical camellia-like Ca2Al1Fu is fabricated via a Ca/Al competitive coordination combined with alkaline -assisted strategy to tailor the morphology and porous structure. Subsequently, we systematically explore how the kinetic, thermodynamic, pH, and coexisting ions parameters employed during fluoride adsorp-tion influence the resulting uptake behavior of Ca2Al1Fu. Further, sensory evaluation of the tea after adsorption is explored to determine the optimal dose that makes Ca2Al1Fu as a practical adsorbent for application. Importantly, the fluoride adsorption capacity of optical CaAlFu with mixed CaAl metals molar ratio of 2:1 is 3.15 and 2.11 times higher than that of pristine CaFu and AlFu, respectively. Theoretical results reveal that the boosting selective fluoride removal can be ascribed to the specific interactions between fluoride and CaAl coordinatively unsaturated bimetallic centers. These results present an effec-tive design strategy for the construction of bimetallic MOFs with hierarchically porous structures for broad prospect in adsorption-based applications. (c) 2023 Elsevier Inc. All rights reserved.