Metal organic framework (La-PDA) as an effective adsorbent for the removal of uranium(VI) from aqueous solution

A two-dimensional lanthanum(III) porous coordination polymer was prepared, characterized and applied as an efficient adsorbent for the removal of uranium from aqueous solution. Lanthanum(III) was the metal center of MOFs, and the deprotonated anions of pyridine-2,6-dicarboxylic acid (H-2 PDA), PDA(2-) was the organic ligand, this MOF was name as La-PDA, which was synthesized by hydrothermal reaction method. Scanning electron microscope (SEM), Fourier transform infrared (FTIR), powder X-ray diffraction (PXRD) and thermal gravimetric (TG) analysis were used for characterization, and the results indicated that the La-PDA composites were successfully prepared. Compared with traditional adsorbents of uranium, La-PDA showed excellent adsorption properties. The adsorption capacity was 247.6 mg g(-1) at 298 K and pH 4.0. The adsorption equilibrium achieved within 120 min, and the adsorption process was exo-thermic and spontaneous. The absorption mechanism of La-PDA was also explored, from the XPS spectra, the pyridine-like nitrogen atoms (C=N-C) and carboxyl oxygen atoms (-COO-) contributed to the adsorption of uranium. The results suggested that PDA(2-) was a potential ligand of uranium adsorption, La-PDA composites were effective adsorbents for the removal of uranium from aqueous solution.