Rapid and selective uranium adsorption by glycine functionalized europium hydroxide

A composite material of europium hydroxide (Eu(OH) 3 ) and glycine (Gly) is synthesized successfully to produce single phase material (Eu(OH) 3 -Gly) which exhibits extremely selective capturing and high removal rate towards uranyl (UO 2 2+ ) ion in an aqueous solution. Eu(OH) 3 -Gly displayed distribution coefficient (K d ) of 3.23 × 10 7 mL/g and removal rate of 100% to lower UO 2 2+ ion concentration from 25 ppm to <1 ppb inside 15 min and these criteria place Eu(OH) 3 -Gly among the top existing adsorbents for such adsorption. Adsorption kinetics for UO 2 2+ follows pseudo-second-order model, proposing a chemisorption adsorption mechanism mainly via H 2 N-U-NH 2 and O-U-O interactions. Eu(OH) 3 -Gly showed good stability after the removal of uranyl ion as investigated by FT-IR and thermogravimetric analysis (TGA) methods. According to TG analysis, Eu(OH) 3 -Gly showed less weight loss (23.7%) after adsorption compared with that of before adsorption (32%), suggesting that the attachment of uranium to the adsorbent contributed for the improvement of the thermal stability of Eu(OH) 3 -Gly.