Effect of HNO₃ Concentration on the Pd(II) Extraction Properties using a Thiodiglycolamide Compound

Abstract

Dependence of the Pd(II) complexes extracted with N,N'-dimethyl-N,N'-ditolyl-thiodiglycolamide (MTTDGA) in chloroform on HNO 3 concentrations in the aqueous phase was investigated by liquid-liquid extraction experiments and Fourier-transform infrared spectroscopy (FT-IR) measurements. The extraction behavior of Pd(II) clearly differed between 0.5 M and 8 M HNO 3 concentrations. It took ~8 h and <5 min to attain the extraction equilibrium at 0.5 M and 8 M HNO 3 , respectively. The apparent stoichiometry of MTTDGA:Pd(II) in the extracted complexes obtained from the loading test was 1:1 at 0.5 M HNO 3 and 2:1 at 8 M HNO 3. FT-IR spectroscopy results suggested that the amide oxygen atom(s) coordinated to Pd(II) in both the 1:1 and 2:1 MTTDGA:Pd(II) complexes, but the coordination mode of the MTTDGA molecule(s) differed.