Preferential elimination of negatively charged micropollutants in water over cerium-based metal–organic frameworks

In this study, three groups of harmful chemicals at trace amounts (μg/L) in water with extremely high environmental risk were preferentially removed over cerium-based UiO-66 and MOF-808, including nonsteroidal anti-inflammatory drugs (NSAIDs), quinone antibiotics, and perfluoroalkyl carboxylic acids (PFCAs). Results found that cerium-oxygen clusters with oxygen vacancies and larger pore sizes effectively adsorbed targets by both chemical and physical mechanisms. Remarkably, log K_ow of five PFCAs (PFPeA, PFHxA, PFOA, PFNA, PFDA) with increasing lengths of alkyl chains strongly correlated (R² = ∼0.99) with ln (v₀) and Q_e. In contrast, Ce-MOFs rapidly adsorbed NSAIDs and quinone antibiotics, ranking the excellent adsorbents reported so far (e.g., Q_e, _OFC = 419.8 mg/g on MOF-808). Hydrophobic, diffusion, and electrostatic interaction mechanism were systematically studied using mathematic models, including pseudo first/second-order, Elovich, and Weber-Morris intraparticle diffusion ones. Thanks to the generation of reactive species (e.g., •OH, ¹O₂, •O^2– and oxygen vacancies) over cerium-oxygen clusters under the irradiation of solar light, aromatic NSAIDs were completely decomposed (>99 %) within 60 min. This study offers helpful guidance for the preferential removal of ECs in water.