N-(2-(2-pyridyl)ethyl)chitosan: Synthesis, characterization and sorption properties

The method of producing N-2-(2-pyridyl)ethylchitosan (PE-chitosan) with substitution degrees (DS) up to 1.2 has been developed using the “synthesis in gel” approach for direct addition reaction between 2-vynilpyridine and chitosan. Investigation of sorption properties has revealed significantly higher affinity of pyridylethyl fragments to Pt(IV)) and Pd(II) ions compared to the unsubstituted amino groups of chitosan. The maximum sorption capacities of PE-chitosan in 0.1 M HCl solution were estimated as 5.56 mmol/g for Au(III), 3.67 mmol/g for Pd(II), and 2.75 mmol/g for Pt(IV). Sorption capacities of PE-chitosan for transition metal ions at pH 4–8 were 1.5–2.6 higher than those of chitosan with the highest values attained for Cu(II) and Ag(I) ions – 1.50 mmol/g and 1.53 mmol/g, respectively. The PE-chitosan application for preconcentration of Au(III) with subsequent elution with HCl/thiourea mixtures was proved to be efficient for atomic absorption spectroscopy analysis of multi-component solutions with low gold content.