Selective adsorption of Pd(II) over Ag(I) in nitric acid solutions using nitrogen-donor-type adsorbents

[Display omitted] •HNO3 leaching leaves some Pd in Ag solutions after separation from Pd residuals.•N-donor-type adsorbents were used to separate Pd(II) and Ag(I) in HNO3 solutions.•Iminodiacetic acid- and pyridine-bearing adsorbents selectively recovered Pd(II).•Bis-picolylamine-bearing adsorbents adsorbed Pd(II) and Ag(I).•Formation of dinuclear Ag(I) complexes caused Ag(I) adsorption. The HNO3 leaching process is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO3 solutions is essential for promoting efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO3 solutions was investigated using four N-donor-type adsorbents bearing amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), and bis-picolylamine (R-BPA) functional groups. R-IDA and R-Py demonstrated efficient separation of Pd(II) (82 %–99 %) from Ag(I), Cu(II), Ni(II), and Fe(III) (