Trimetallic MOFs (Zr–La–Ce) Adsorbent for Defluoridation with Ultrahigh Selectivity and Performance under a Wide pH Range

Fluoride pollution is a serious environmental problem that is a risk to human health. Hence, the effective elimination of fluoride is urgent. Herein, a novel trimetallic Zr-La-Ce MOF was fabricated with a hydrothermal method and adapted to eliminate fluoride from water media. Characterization showed that the adsorbent presented a flower-like morphological structure with a large specific surface area of 682 m² g^-1. The adsorption property was further evaluated by examining the impact of fluoride concentration, solution pH, and coexisting anions. The adsorption capacity of Zr-La-Ce MOFs is above 110 mg g^-1 at pH 2-9, indicating that Zr-La-Ce MOFs have a wide applied pH range, and the coexisting ions have a tiny impact on the fluoride removal performance, demonstrating an excellent fluoride selectivity. The sorption process adhered well to the Langmuir model and pseudo-second order kinetic model, and the maximum Langmuir sorption capacity was 167.61 mg g^-1. Practical application investigation, regeneration performance evaluation, and safety experiments demonstrated that the Zr-La-Ce MOFs had excellent recycling performance, with the treated water lower than 1 mg L^-1, and no precipitation of metal ions, which has certain potential for practical application and can provide insights and references for the preparation of multimetal MOFs.