Screening ligands for metallurgical applications by the determination of pH of complexation with metals

Ligands containing thiol and/or amine groups were screened for their metal-complexing ability with various metal chlorides (Fe+2, Fe+3, Co+2, Ni+2, Cu+2, Zn+2 and pb+2) in aqueous solution by pH titration. Use of a consistent background matrix (0.1 MNaCl) and methodology overcame the difficulty of comparison of stability constants available from different sources in the literature. This fast, simple screening technique allows the comparison of many ligands with regard to the pH of complexation of metal ions without the difficult or time-consuming task of calculating stability constants.