Separation of nickel and zinc from aqueous solution using triethylenetetramine

Abstract

This study investigates the most suitable conditions for the combined separation of nickel and zinc ions from aqueous solution using triethylenetetramine (Trien) as a neutral organic chelating ligand and sodium dodecyl sulfate (SDS) as an anionic collector for ion flotation. The interaction of nickel ions with Trien at various pHs and Trien concentrations, and that of nickel ions with SDS, are studied spectrophotometrically. The results show that most suitable conditions for ion flotation are a pH of 9.7, a Trien/Ni(II) mole ratio of 2 and an SDS/Ni(II) mole ratio of 2. Flotation results for the nickel–zinc–SDS-Trien solution show that nickel ion removal is higher than that for zinc ions, indicating that the order of ion removal is opposite to the order of increasing crystal ionic radius. The stability constant of the nickel-Trien complex is greater than that for the zinc-Trien complex, leading to higher Trien interactions with nickel ions. At a pH of 9, the removal of nickel and zinc ions reaches a maximum of 88.4 and 79.9% respectively, corresponding to a 9% higher removal of nickel ions compared to zinc ions.