The role of D-glucose in prolonging the lifetime of indium inalkaline cyanide electrolytes

Abstract

Indium is commonly used in various environmental solutions due to its unique properties. However, in the electrodeposition of decorative AuCuIn alloys, its stability in aqueous cyanide solutions is a challenge because it tends to precipitate as In(OH)3. Previous studies have suggested the use of D-glucose in cyanide media to stabilize the solution. However, the lifespan of the solution remains quite short, and the complexes formed in the solutions, as well as the stabilizing mechanism of D-glucose, are unknown. This work investigates the effect of adding D-glucose to stabilize indium salts in cyanide media using experimental data and computational simulations. The reduction of free cyanides in the presence of D-glucose assessed the transformation of D-glucose into D-glucocyanohydrin (DGluCN) in alkaline media. Molecular dynamics simulations showed that the presence of DGluCN decreases the number of intermolecular collisions of indium complexes (In(OH)3 or In(CN)3) at short distances, thereby preventing its precipitation and allowing the species formed by In3+ to remain stable in the solution in their colloidal form. These findings provide a deeper understanding of indium kinetic stabilization at alkaline pH, which could potentially expand the application fields of this metal.