Selectivity of cross-linked poly(N-vinylimidazoles) toward gold (III), palladium (II), platinum (IV): synthesis, mechanism, and recovery

Abstract

As a result of quaternizing cross-linking, poly(N-vinylimidazoles) (PVI) cross-linked with 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane, and 1,5-dibromopentane were obtained, with cationic centers being formed during the modification. It was testified that all studied sorbents allow for the significant recovery (recovery degree (R) ⁓ 60–90%) of gold (III) and palladium (II) from both individual and multicomponent hydrochloric acid solutions in the pH range of 1–5, including in the presence of a 100-fold excess of base metal ions. Depending on the structure of the cross-linking unit, an increase in the sorption selectivity for certain metal ions is achieved in some cases; for example, PVI cross-linked with 1,4-dibromobutane and 1,5-dibromopentane demonstrate high selectivity for palladium(II) sorption in the presence of gold ;(III) from 1–3 mol/L HCl. It has been shown that a 1% thiourea solution in 2 mol/L HCl provides a higher desorption degree for palladium and gold compared to 3.5 mol/L HCl. It is assumed that the sorption of palladium (II) proceeds primarily via complexation with the functional groups of the sorbents, whereas that of gold (III) occurs through electrostatic interaction with quaternized nitrogen atoms.