Complexation of some environmentally friendly carboxylic acid ligands with La³⁺ ion in aqueous solution

Abstract

In search for environmentally friendly metal chelating ligands for industrial applications, protonation, and complex-formation equilibria of iminodisuccinic acid (IDS), 3-hydroxy-2,2′ -iminodisuccinic acid (HIDS), N,N′-ethylenediaminedisuccinic acid (EDDS), and oxydisuccinic acid (ODS) with La³⁺ in aqueous 0.1 mol L⁻¹ NaCl solution were studied at 25°C by potentiometric titration. The model for complexation and the stability constants of the different complexes were determined using the computer program SUPERQUAD. Complex formation was dominated by stable LaL⁻ complexes for all tested ligands.

Keywords:

• Chelating agent
• Stability constants
• Iminodisuccinic acid (IDS)
• 3-Hydroxy-2,2′-iminodisuccinic acid (HIDS)
• N,N′-Ethylenediaminedisuccinic acid (EDDS)
• Oxydisuccinic acid (ODS)
• La³⁺