Aqueous colloidal suspensions were generated by reacting nuclear waste glasses with groundwater at 90 °C at different ratios of the glass surface area to solution volume (S/V). The colloids have been characterized in terms of size, charge, identity, and stability with respect to salt concentration, pH, and time, by examination using dynamic light scattering, electrophoretic mobility, and transmission electron microscopy. The colloids are predominantly produced by precipitation from solution, possibly with contribution from reacted layers that have spalled from the glass.The following implications for modeling the colloidal transport of contaminants have been derived from this study: (1) The sources of the colloids are not only solubility-limited real colloids and the pseudo colloids formed by adsorption of radionuclides onto a groundwater colloid, but also from the spalled surface layers of reacted waste glasses. (2) In a repository, the local environment is likely to be glass-reaction dominated and the salt concentration is likely to be high, leading to rapid colloid agglomeration and settling; thus, colloid transport may be insignificant. (3) If large volumes of groundwater contact the glass reaction site, the precipitated colloids may become resuspended, and colloid transport may become important. (4) Under most conditions, the colloids are negatively charged and will deposit readily on positively charged surfaces. Negatively charged surfaces will, in general, facilitate colloid stability and transport.

The anodic polarization of Fe, Co, Ni, Cu, and Mo have been studied at 375° and 450°C in molten normalLiCl‐normalKCl eutectic containing lithium oxide. Current‐potential curves obtained exhibit characteristic corrosion‐passivation behavior similar to that found in aqueous systems. Anodic corrosion rates were found to be considerably lower than for the metals in pure normalLiCl‐normalKCl electrolyte. Cyclic voltammetric study showed reversibility in the reduction of oxide films on Fe, Cu, and Co, quasi‐reversible for Ni, and irreversible for Mo. Potentiostatic and galvanostatic transient measurements on iron at 450°C indicate a dissolution‐precipitation mechanism for film formation with growth limited by high field ion transport.

The electrochemical behavior of iron phthalocyanine (FePc) films, supported on gold and other metal substrates, was studied in 0.05M H~SO4 solution using cyclic voltammetry and rotating disk (with ring) electrode techniques. Reduction of oxygen on the electrodes was observed to be accompanied by the production of hydrogen peroxide. Previously reported "deactivation" of FePc films with repeated cycling was found to be associated with the adsorption of peroxide intermediates. Multiple redox waves on FePc in the region of -0.05 to -1.0Vvs. Hg/Hg~SO4 have been assigned as due to hydrogen adsorbed on different surface sites. * Electrochemical Society Active Member. Key words: iron phthalocyanine, cyclic vo!tammetry, rotating disk electrode. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-05-16 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.251.14.35 Downloaded on 2015-05-16 to IP