ADSORPTION AND DESORPTION OF RARE-EARTH ELEMENTS WITH SYNTHESIZED POLYACRYLAMIDE

Polyacrylamide (PAAM) was synthesized by plasma-initiated polymerization of acrylamide and NN'-methylenebisacrylamide. Batchwise adsorption experiments demonstrated that PAAM had the characteristics to adsorb rare earth elements {Y(III), Ce(III), Eu(III), Ho(III) and Er(III)} and the adsorption of the rare earth elements onto PAAM depended on pH. The 50% adsorption pH for each element is as follows: Ce(III), 3.4; Y(III), 3.6-, Er(III), 3.7; Ho(III), 3.9; Eu(III), 4.0. Adsorption equilibrium of the rare earth elements onto PAAM was attained within 15 min. These elements were released from the resin quantitatively by treatment of the PAAM with 0.1 M (mol/dm3) EDTA (pH 8.5) solution. A column packed with PAAM was used for the adsorption and desorption of the elements. As a result, the elements except Er(III) were adsorbed and desorbed quantitatively. Further, influence of co-existing anions on adsorption of cerium and europium was studied. From above results, it was found that PAAM had the possibility for being used as an adsorbent of rare earth elements.