Liquid-liquid extraction of manganese(II), copper(II) and zinc(II) with acyclic and macrocyclic Schiff bases containing bisphenol A subunits

Abstract

Acyclic and macrocyclic Schiff bases containing bisphenol A subunits were synthesized and the effect of ligand atoms on the liquid-liquid extraction of manganese(II), copper(II) and zinc(II) was studied. The phenol groups in the Schiff base moiety led to a large increase in the percent extraction of transition metal ions. The substitution of methoxy groups for phenolic OH ligands resulted in a marked decrease in the extractability of metal ions. Compared with a macrocyclic Schiff base, the corresponding acyclic counterpart was found to have a reasonable reactivity toward metal ions and better solubility in organic solvents. The copper(II) complexes with acyclic Schiff bases were quantitatively extracted into nitrobenzene without the presence of bulky counter anions. Mutual separation of zinc(II), copper(II) and manganese(II) can be achieved by a proper selection of pH and extractant.