REDOX-CONTROLLED SOLUBILITY OF PALLADIUM IN A BOROSILICATE GLASS MELT

Palladium establishes the Pd2+–Pd0 redox equilibrium in a reference alkali borosilicate melt. Most of the palladium exists as the insoluble metal, with only a small fraction of the palladium present as the divalent palladium ion dissolved in the melt. The relative reduction potential of this Pd2+–Pd0 redox couple in the reference glass melt is greater than such easily reduced couples as Ni3+–Ni2+ and Mn3+–Mn2+. Palladium metal in glass melts containing appropriate amounts of nickel and sulfur readily partitions into an immiscible nickel sulfide phase; palladium also tends to associate with tellurium in insoluble particulates. Copyright © 1990, Wiley Blackwell. All rights reserved