Computer-augmented modeling studies of Pb(II) and Cd(II) complexes with maleic acid in ethylene glycol–water mixture

Abstract

Chemical speciation of binary complexes of Pb(II) and Cd(II) ions with maleic acid have been studied pH metrically in the concentration range of 0–50% v/v ethylene glycol (EG)–water mixtures maintaining an ionic strength of 0.16 molL−1 at 303 K. Alkalimetric titrations were carried out in different relative concentrations of metal and maleic acid. Stability constants of various models of binary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected are ML2, ML3, and ML2H for Pb(II) and Cd(II). The chemical speciation, metal bioavailability, and transportation are explained based on the distribution diagrams.

Keywords

• Binary complexes
• maleic acid
• ethylene glycol (EG)
• stability constants