Highly Selective Lithium Ion Adsorbents: Polymeric Porous Microsphere with Crown Ether Groups

In this study, we prepared and applied polymeric porous microsphere adsorbents with selectivity for Li + extraction from aqueous solution. We synthesized the adsorbents by suspension polymerization using methacryloyoxyme-12-crown-4 (M12C4) as a functional monomer, which had been synthesized from 2-hyroxymethyl-12-crown-4 and methacryloyl chloride. We verified the chemical composition by solid nuclear magnetic resonance ( 13 C-NMR) spectroscopy and observed the porous structure by scanning electron microscopy (SEM). We conducted adsorption isothermal and kinetic tests to determine the adsorption properties. It was found that the adsorbents showed high adsorption efficiency and an adsorption equilibrium time of 200 min. In addition, since the crown ether used in this work could form a stable complex with Li + , we observed good selectivity for Li + in the prepared solution compared with other ions such as Na + , K + , Mg 2+ , and Ca 2+ . We reused the adsorbents five times with no significant decrease in adsorptive capacity.