Selective removal of radioactive 210Pb(II) and nonradioactive Pb(II) isotopes from Cu(II)-rich acidic chloride solution by a new polyamine anion exchanger

•Radioactive 210Pb(II) in HCl solution (1–3 M) is adsorbed by a new polyamine resin.•The adsorption of radioactive 210Pb(II) exhibits the high selectivity over Cu(II).•The highest separation factor of Pb(II) over Cu(II) from mixed solution is 1960.•Both chelation and ion association contribute to a combined adsorption mechanism.•The mechanism is illustrated at atomic level by X-ray absorption spectroscopy.