Rhenium(VII) and technetium(VII) separation from aqueous solutions using a polyethylenimine-epichlorohydrin resin

The ReO4- and (TcO4-)-Tc-99 removal from aqueous solutions using a polyethylenimine-epichlorohydrin resin was investigated in absence and presence of background electrolyte (0.01 and 0.50 M NaCl). Re(VII) and Tc(VII) sorption isotherms were obtained for solutions with 2.3 <= pH <= 8.9 and concentration 0.21-26.9 mmol Re/L and 5 x 10(-3) -5 x 10(-2) mmol Tc-99/L. The highest uptake for both elements (R-d approximate to 10(4) mL/g) was observed for solutions with pH <= 4 and C-NaCl <= 0.01 M, hinting towards the existence of protonated groups contributing to the sorption of anions under acidic conditions and to the competition of Cl-. The sorption data were modeled using the Langmuir and Freundlich equations.