Sorption behaviour and mechanism of ytterbium(III) on imino-diacetic acid resin

The sorption behaviour and mechanism of a novel chelate resin, imino-diacetic acid resin (IDAAR), for Yb(III) has been investigated in HAc–NaAc medium. The sorption of Yb(III) obeys the Freundlich isotherm. Optimum sorption for Yb(III) on IDAAR is at pH 5.13 and the statically saturated sorption capacity is 187 mg/g resin at 298 K. Yb(III) can be eluted using 1~2 mol L− 1 HCl and the resin can be regenerated and reused without apparent decrease of sorption capacity. The apparent sorption rate constant is k298 = 1.57 × 10− 5 s− 1; the apparent activation energy is 13.8 kJ mol− 1 and the enthalpy change ΔH of IDAAR for Yb(III) is 29.8 kJ mol− 1. The sorption mechanism of IDAAR for Yb(III) was examined by using chemical methods and IR spectrometry. The molar coordination ratio of the functional group of IDAAR to Yb(III) is 3:1 with the coordination compound formed between oxygen atoms in the functional group of IDAAR and Yb(III).