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The electrolytic removal of Ag(I) on a platinum rotating cylindrical electrode (RCE) in the liquid wastes generated from the mediated electrochemical oxidation (MEO) process was studied under a constant current. The effects of various parameters such as applied current density, concentration of HNO3, temperature and hydrodynamics on the removal efficiency and the morphology of the electrodeposits were investigated. The removal efficiency higher than 98% could be obtained in the concentrations of HNO3less than 3 M (=mol/dm3) with the current efficiency more than about 95%. At lower concentrations of HNO3, higher rotational rates, and lower temperatures, larger removal efficiency could be obtained.

Decontamination characteristics of urban building surfaces, based on the covering of clay suspensions, have been studied. The cation converting conditions of clay suspensions were determined by a flocculation series test. Contaminated specimens for test purposes were pre-pared by application of a radioactive solution which had been extracted from the soil of a 2 km zone of the Chernobyl Nuclear Power Plant (ChNPP). The results of this study show that clay suspension technology was effective for decontamination of an urban environment. Especially, K-NH4clay suspension shows good decontamination performance.

AbstractThe dissolution behavior of Cu metal in hydrogen peroxide (H2O2)-ethylenediaminetetraacetic acid (EDTA) solution was studied through both electrochemical and chemical tests. In the electrochemical experiments, the open circuit potential (OCP) of Cu electrode at low H2O2concentration below 0.5wt% was determined by Cu anodic reaction and H2O2cathodic reaction. On the other hand, the OCP in higher concentration above 2 w/t% of H2O2approached to 70 mV vs. SCE, since the redox reaction of H2O2was so dominant reaction that the Cu anodic reaction was masked. The anodic polarization curve of Cu around the OCP of 70 mV in the range between -200 and 200 mV in the solution without H2O2showed the maximum Cu dissolution reaction front, while those of both carbon steel and Inconel 600 in the same potential range were situated in the passivation region. The anodic polarization behaviors of Cu in the H2O2concentrations above 1 wt% were examined by a potentiostatic method along with a weight loss measurement. The anodic Cu dissolution current estimated from the weight loss measurement in the solution containing more than 1 wt% of H2O2was higher than that predicted by the polarization curve of Cu in the H2O2-free solution. The dissolution reaction rate of Cu in the H2O2solution linearly increased with H2O2concentration. This result indicated that the dissolution reaction rate of Cu in the presence of H2O2was enhanced by a reaction between Cu and H2O2, resulting in the shift of the polarization curves depending on H2O2concentration. The experimental correlation equation based on the above results described well the overall dissolution reaction rate of Cu in H2O2concentration ranges below 1 wt% and above 2 wt% in the EDTA solution.