Interaction of polyamines with perrhenate ions: influence of Brønsted basicity of the polymer matrix
摘要
The adsorption of ReVII was estimated for polyethyleneimine (PEI), polyallylamine (PAA), and polyaminostyrene (PAST) possessing different Brønsted basicity. A high adsorption of ReVII (up to 97%) from the acetate buffer solution was observed in the pH range of 2.8–3.1 for PEI and PAST, and in the pH range of 2.8–5.2 for PAA. The kinetic data indicated a mixed diffusion mode for the sorption with a significant contribution of the step of chemical interaction between ReVII and functional groups of the sorbents. Rapid establishment of the equilibrium (within 5–10 min) was observed for all the sorbents in contrast with industrial anion exchangers used as the reference. The isotherms plotted for the sorption of ReVII within the concentration range of 5–400 mg L−1 were mathematically processed within the framework of the Langmuir, Freundlich, and Dubinin—Radushkevich models. The affinity of ReVII towards the sorbents decreases in the series of PAA > PEI > PAST. The values calculated for the sorption capacity of PAA (1.81 mmol g−1), PEI (2.43 mmol g−1), and PAST (0.98 mmol g−1) were not inferior to the corresponding values for modern weakly basic sorbents. The presence of a 200 fold excess of CuII in the solution caused virtually no effect on the sorption of ReVII. At 200 fold excess of MoVI, the adsorption of ReVII on PAST (A = 94%) and PEI (A = 85%) remained at a high level, whereas in the case of PAA, the effect of MoVI was more significant decreasing the sorption by 36.5%.