Extraction of Cd(II) and Zn(II) with Dialkylthiophosphinic Acid and Hexadentate Nitrogen-donor Ligand

Abstract

Abstract The extraction equilibrium of Cd(II) and Zn(II) with a commercial extractant, Cyanex 301, and an aqueous complexing agent, TPEN [N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-ethanediamine] was measured. When TPEN in amounts equimolar with heavy metal (Cd or Zn) was added in the aqueous solution, only the extraction of Zn was depressed. Then, the extraction constant of Cd was little changed and that of Zn was decreased to about 10−4 times. TPEN acts as a strong masking agent for Zn.