Copolímeros de Estireno-Divinilbenzeno Impregnados com Agentes Complexantes Organofosforados para Separação de Terras Raras
PALAVRAS-CHAVE: Copolímeros de Estireno-Divinilbenzeno Impregnados com Agentes Complexantes Organofosforados para Separação de Terras Raras; Celina C. R. Barbosa, José Waldemar S. O. Cunha, Viviane G. Teixeira, Fernanda M. B. Coutinho; Styrene-divinylbenzene copolymers used in extraction chromatography were synthesized in presence ofselective cheIating agents for rare earths: DEHPA, bis(2-ethylhexyl) phosphoric acid, and EHEHPA, bis(2-ethylhexyI) phosphonic acid. The copolymers were prepared by suspension polymerization technique using the pure chelating agents and its mixture with toluene (TOL) as diluents. The influence of synthesis conditions such as chelating agent/TOL ratios, dilution degree of monomers and amount of DVB on the porous structure of the copolymers were studied. The porous structure was characterized by the apparent density, fixed pore volume, surface area and by optical and scanning electron rnicmscopy. The perfom1ance of the copolymers in the separation process of rare earths was evaIuated. The total cheIating capacity of each copoIymer and the chelating kinetics in relation to gadolinium ion were deterrnined. The chelating agent content of the copolymers depended on the amount ofchelating agents employed in the synthesis. The highest amount ofchelating agent that can be used in the synthesis in order to produce copolymers with high chelating capacity and good mechanical properties was detennined. The total chelating capacity varied with the content ofthe chelating agents in the copolymer and the chelating kinetics was dependent mainly on the pore diameter, because this parameter determines the diffusion rate ofthe ions through the copoIymer stnlcture.
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