Post-synthesizing modification of nanostructured Zr-MOFs to increase the adsorption capacity of heavy metals from an aqueous solution

In the present work, a method of post-synthetic modification of metal-organic frameworks (MOFs) with a zirconium based UiO-66 structure was proposed to increase the removal efficiency of heavy metal ions from aqueous solutions. The resulting Zr-MOFs were characterized by the methods of powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy dispersive X-Ray analysis (EDX), ATR-FTIR analysis and N₂ adsorption– desorption. The specific surface area of the unmodified and modified UiO-66 was estimated by BET method using the strict criteria suggested by Rouquerol. The volume and size of pore were calculated by the Horvath-Kawazoe method using data on the magnetic susceptibility and permittivity of the samples. It is shown that post-synthetic modification of MOF by ethylenediaminetetraacetic acid (EDTA) molecules leads to an increase in the adsorption of cadmium and strontium ions from the aqueous solution, which proves the role of EDTA molecules as a universal trap of metal ions.