Conditions and mechanisms of noble metals ions sorption in the process of their preconcentration on the new polyvinylpyridine sorbents

Autor: Vadim A. Davankov, I. F. Seregina, Mikhail A. Bolshov, A.S. Dubenskiy, Ilya V. Shigapov, L. A. Pavlova, Yulia A. Maksimova
Rok vydání: 2020
Předmět:
Zdroj: Monatshefte für Chemie - Chemical Monthly. 151:1291-1303
ISSN: 1434-4475
0026-9247
Popis: Natural sources of noble metals (Ru, Rh, Pd, Os, Ir, Pt, Au) are exhaustible, thus the extraction of metal from anthropogenic sources seems very promising. This work presents an investigation of new N-heterocyclic sorbents based on polyvinylpyridine for reversible extraction of noble metals from complex matrix solutions. This type of sorbents shows good resistance to aggressive acidic media and sufficient sorption capacity in both dynamic and static modes. It was found, to achieve quantitative sorption of Rh and Ir it is necessary to convert these analytes completely into their chloride form at the stage of sample preparation. Based on a series of experimental data, possible mechanisms of retention of noble metals’ chlorocomplexes on this type of sorbents are proposed. The UV–Vis spectra of various noble metals chlorocomplexes were studied in the presence of model compounds that simulate the repeating units of the sorbents. We assume that the chlorocomplexes of Rh, Ir, and possibly Ru form simple ion pairs with positively charged sorption sites. While Pd, Pt, and Au form more stable complexes (possibly intra-sphere) with sorbent units. The mechanism of Os sorption is unclear and requires a more detailed investigation. This information helps to select suitable desorption solutions for the extraction of analytes from the sorbent. The desorption solution should contain electrolytes, acid, and complexing reagents necessary for the quantitative recovery of noble metals due to the different sorption mechanisms and the various contribution of electrostatic forces to the efficiency of chlorocomplexes retention.
Databáze: OpenAIRE
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