Electrochemical recycling of Pd and Ag from simulated high-level liquid waste

For the recycling of Pd and Ag from high-level liquid waste (HLLW), the electrochemical behaviors of Pd and Ag in the simulated HNO₃ solutions were investigated by cyclic voltammetry and potentiostatic deposition. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe the deposits morphology and to evaluate their composition. The results indicate that the formation of NO₂⁻ helps to dissolve Ag while Ag is electrodeposited. When Pd and Ag are electrodeposited together, more metals are gained in the same time, and the deposited Ag does not dissolve in this situation. The metals are electrodeposited completely at the potentials from −0.4 to −0.6 V (vs MSE) and the deposits contain Ag and PdH_x. The electrodeposition of Pd can boost hydrogen evolution, and then the reaction between H₂ and NO₂⁻ is sped up, thereby lowering the concentration of NO₂⁻ and inhibiting the dissolution of Ag.