Synthesis, characterization and structure effects on preconcentration and extraction of N,N′-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy) butane towards some divalent cations

Separation with solvent extraction of Cu(II), Co(II) and Ni(II) from aqueous solution using N,N′-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy)butane (H2L) as the new extractant has been studied. The new Schiff base, was synthesized by reaction of 1,4-bis-(p-aminophenoxy)butane and salicylaldehyde. Microanalytical data, elemental analysis, UV-vis 1H NMR and 13C NMR spectra and IR-spectra were used to confirm the structures. The extractability and selectivity of divalent cations was evaluated as a function of relationship between distribution ratios of the metal and pH or ligand concentration. Cu+2 showed the highest extractability and selectivity at pH 7.8, whereas Ni+2 and Co+2 showed at pH 9.2. From the loaded organic phase, Cu(II), Co(II), Ni(II) stripping were carried out in one stage with aqueous acid solution including various concentrations of HCl. The stripping efficiency was found to be quantitative in case of 1.5 M HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complexes extracted are the simple 1:1 chelates, CuL, CoL, NiL.