Silver deposition from its nitrate solutions by hydrogenated palladium

Abstract

The currentless deposition of Ag⁺ cations from silver nitrate solutions has been found on the surface of hydrogenated Pd (Pd−H). This process has been shown to proceed via a chemico-catalytic mechanism. It has been demonstrated that the major fraction of silver deposited onto the Pd-H system from the nitrate solutions in the first 0.5–1 h of holding in the solution. A minimal size of silver crystallites (26–40 nm) was found when deposited from the diluted nitrate solutions that contain 0.32–2.5 g/L of Ag. The study has revealed that the currentless Ag deposition on the Pd–H surface is accompanied by the formation of the colloid phase of Ag crystallites. It has been established that the Pd–H system could purify solutions of Ag⁺ when the amount of hydrogen in Pd exceeded the amount of Ag⁺ in the solution.