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[Display omitted] Bimetal oxide is a popular defluorinating material. Hexadecyl trimethyl ammonium bromide (CTAB) as a surfactant successfully synthesizes a novel lanthanum-zirconium phosphate to remove fluorine from groundwater. Lanthanum-zirconium phosphate at a Zr/La molar ratio of 2 exhibited a specific surface area of 455.14 m2/g with a wide pore size, which was achieved by incorporating lanthanum into materials and removing CTAB through calcination. The maximum fluoride adsorption capacity is 109.17 mg/g, which is tenfold that of mesostructured zirconium phosphate. Specifically, analysis revealed that mZrP and LamZrP2-1 were amorphous, which is consistent with HAADF-STEM. The fluoride adsorption fitted well with the pseudo-second-order equation model and Langmuir isotherm mode. LamZrP2-1 had potent anti-interference ability without PO43-. Moreover, LamZrP2-1 was reusable for at least six cycles of adsorption–desorption with little influence. The adsorption mechanism of fluoride was discussed by X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy (NMR) analysis, and Fourier transform infrared (FTIR) spectroscopy. Fluoride was captured by LamZrP2-1 via charge attraction, ligand exchange of different bond strengths, and ion exchange. Lanthanum-zirconium phosphate is important not only in the research and development of bimetal oxides but also in the treatment of groundwater for fluoride removal. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this study, we prepared a hydrothermal carbon-based supramolecular organic framework (HTC-MA-TMA) by grafting melamine and trimesic acid on hydrothermal carbon (HTC) for efficient removal of U (VI) from aqueous solutions. The nano-sized supramolecular organic framework (SOF) particles consisted of N-donor-containing melamine and O-donor-containing trimesic acid self-assembled through hydrogen bonds. Their large number of specific active sites acted as the immobilization center for capturing U (VI). Chemical modification facilitated the dispersion of the SOF particles on HTC, which was synthesized using a novel covalent/non-covalent bond strategy. The HTC-MA-TMA adsorbent exhibited exceptional U (VI) adsorption capacity (271.83 mg/g) because of the coordination interaction between UO 2 2+ and its ligands (amino, carboxyl and amide groups). The adsorption equilibrium was achieved within 30 min and followed a pseudo-second-order equation, suggesting the occurrence of a chemical adsorption process. Furthermore, the U (VI) ions adsorbed onto the HTC-MA-TMA adsorbent could be easily desorbed using 0.1 M HNO 3 solution. This regeneration caused no significant decrease in the sorption capacity of the adsorbent. These results suggest that advanced HTC-MA-TMA adsorbent can be applied in the nuclear-fuel industry for extracting U (VI) from radioactive wastewater. [ABSTRACT FROM AUTHOR]