RARE EARTHS SEPARATION FROM WEEE BY SYNTHETIC POLYMERS MODIFIED CLAYS

Two natural smectite mineral clays (STx-1b and SWy-2) were modified by intercalating two different polymers having chelating properties, namely a poly-carboxylic poly-ether polymer and a phosphonate poly-carboxylic poly-ether polymer. The obtained materials were characterized by FT-IR, thermogravimetric analysis (TGA) and X-ray diffraction (XRD) while the amounts of intercalated polymer were estimated by COD (Chemical Oxygen Demand) analysis of the residual amounts in solution. The modified clays were contacted with an aqueous Lanthanum solution (chosen as representing element of REs family), and the Lanthanum adsorbed and/or chelated by the modified clays was analysed by ICP-OES of the contacted solution. Finally, release tests were performed on the different samples in order to verify the organo-clay capability not only to capture but also to recover metal ions. The obtained results showed that the experimental procedure was appropriate to intercalate both polymers in both clays and that the synthesized organo-clays were effective in both Lanthanum adsorption and release processes. In particular it was possible to adsorb the 40- 60% of the La3+ ions present in the contacting solution, while an effective release was obtained at pH lower than 3.