Ionophoretic studies on mixed complexes : Metal-acetic acid-nitrilotriacetate

Electrochemical Laboratory of Green Synthesis, Department of Chemistry, University of

Allahabad, Allahabad-211 002, Uttar Pradesh, India

E-mail : rkp.singh@rediffmail.com

Manuscript received online 11 July 2012, revised 09 August 2012, accepted 10 August 2012

Quantitative indication of a complex formation comes from the estimation of the stability or formation constants characterizing the equilibria corresponding to the successive addition of ligands. The binary equilibria of metal ions, viz. Fe^III, Cu^II, Ni^II and Co^II-acetic acid and also mixed equilibria Fe^III/Cu^II/Ni^II/Co^II-acetic acid-NTA (nitrilotriacetic acid) have been studied using ionophoretic technique. The stability constants of metal-acetic acid binary complexes are found to be 4.42, 3.58, 3.42 and 3.37 that of metal-acetic acid-NTA mixed complexes have been found to be 6.34, 6.31, 6.14 and 6.11 for Fe^III, Cu^II, Ni^II and Co^II complexes, respectively at 25 °C and ionic strength µ = 0.1 mol dm^-3 (HCIO₄).