Voltammetric studies on the redox behaviour of Cr, Mn, Cu, Sb and As ions in Na2O–B2O3 melts

Abstract

The redox behaviour of Cr, Mn, Cu, Sb and As ions in Na₂O–B₂O₃ melts has been studied using cyclic voltammetry, in which Cr⁶⁺/Cr³⁺, Mn³⁺/Mn²⁺, Cu²⁺/Cu⁺/Cu⁰, Sb⁵⁺/Sb³⁺/Sb⁰, and As⁵⁺/As³⁺/As⁰ redox reactions were observed. The relations between redox equilibria and the basicity of the solvent melts, i.e. an analogue of the Pourbaix diagram, are presented. The diffusion coefficients of Cr⁶⁺, Mn³⁺, Cu²⁺ and Sb⁵⁺ and the temperature dependences were evaluated.