Stability and reusability of amine-functionalized magnetic-cored dendrimer for heavy metal adsorption

Abstract

The optimal storage period/condition and the number of repeated use with regenerations were studied in this research in order to fully utilize magnetic-cored dendrimers (MDs) terminalized with amine groups as adsorbents. MDs terminalized with amine groups were synthesized and characterized with X ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, surface area analysis, vibrating sample magnetometry, and zeta potential analysis to confirm successful synthesis. The order of adsorption affinity to the MDs was Pb2+ > Cd2+. The effective period of the synthesized MDs was 56 days, and the storage condition for the MDs was in a dry vial. Hydrochloric acid was chosen as the desorption agent to evaluate the regeneration efficiency. After seven regeneration cycles, the adsorption efficiency was approximately 80 %, but it gradually decreased to 55 % after fifteen cycles due to insufficient desorption of loaded heavy metal and loss of adsorbent in the acidic condition during the desorption process. Iron leaching from the MD cores and deterioration of organic branches during desorption were the main reasons for the adsorbent loss. The fraction of iron leaching was dependent on the acidity while the organic carbon leaching fraction was not severely affected by the different hydrochloric acid concentrations.