The effect of diethylenetriamine on the formation of Cu2+–, Ni2+–, and Fe3+–amyl xanthate ion complexes

The effect of diethylenetriamine (DETA) on the formation of Cu2+–, Ni2+– and Fe3+–amyl xanthate ion (AX−) complexes was studied by UV spectroscopy. The absorption spectra of solutions containing metal ions (Mn+) and AX− or Mn+ and DETA were studied to determine the λmax and, when possible, the molar absorptivities of the species in solution. In the Cu2+ and Ni2+ systems, the change in the absorption bands of the M2+–AX− complex and/or AX− when DETA was added to solutions of fixed M2+/AX− ratios was used to propose a reaction scheme. DETA was shown (1) to dissolve M(OH)2 and (2) to suppress the formation of M(AX)2 depending on the M2+/AX− ratio. DETA dissolves Cu(OH)2 instantaneously and quantitatively whereas the dissolution of Ni(OH)2 by DETA is very slow. While the formation of Ni(AX)2 is dependent on the M2+/AX−/DETA ratio, the formation of Cu(AX)2 was not affected significantly by the solution composition. The M(AX)2 self-reduction products, CuAX and NiAX isolated from solutions containing M2+, AX−and DETA were characterized using atomic absorption and FT-IR spectroscopy. Fe3+ behaves differently than Cu2+ and Ni2+ with AX− and/or DETA. Even in the presence of a large excess of AX− and/or DETA, Fe3+ exists almost exclusively as Fe(OH)3 at a pH of 9.3. DETA decreases the amount of Fe3+–AX− complex in solution.