Ionic Strength dependence of Formation Constants: Complexation of Cobalt(II) With thiazolyl blue formazan in a Non-Ionic Micellar Medium

This paper describes the complexation of cobalt(II) with thiazolyl blue formazan in a micellar medium at the pH range 3 to10, using Spectrophotometric techniques. The influences of pH and surfactant amount have been also tested. The composition of the complex was determined by the continuous variation (Jobmethod) and mole-ratio methods. It was concluded that Co2+ forms a mononuclear 2:1 complex with thiazolyl blue formazan of the type CoL2- at pH = 6. Finally, the formation constants of the complex were evaluated at 25 ºC under ionic strengths ranging from 0.1 to 1 mol dm-3 of potassium nitrate.