Cu and Pd depositions onto a TiN layer with displacement reactions were investigated at three temperatures (25ºC, 50ºC, 70ºC) using various fluoride solutions (pH1.6-5.2). Although both Pd and Cu were expected to be deposited onto TiN thermodynamically, Cu deposition did not take place unless the underlying Si layer was exposed to a fluoride solution, while Pd deposits were observed on the TiN layer under all conditions examined. This is because the reduction of protons is preferential to the Cu deposition on the TiN layer. The smallest Pd particles, with a diameter of about 50nm, were obtained at 70ºC from a fluoride solution of pH5.2. The deposition rate and morphology of Pd were dependent on the pH and temperature of the solution. The dissolution of the TiN layer and the deposition of Pd were accelerated with decreasing pH, suggesting that, when the pH of the solution was low, most of the electrons released from the TiN were consumed for the reduction of protons.
High purity Cu electrodeposition from a CuCl-1-Butylpyridinium chloride (BPC) ambient-temperature molten salt electrolyte has been investigated. In this study, silver was examined as an impurity. Ag did not electrodeposit in the Cu deposit and the Cu purity was 99.9999%, if the Ag(I) ion concentration was controlled to be less than 10 ppm in the 66.7mol%CuCl-33.3mol%BPC melt and less than 12ppm in the 44.0mol%CuCl-56.0mol%BPC melt. In addition, a method removal of the Ag(I) ion from the melt was studied. The method of refining by galvanostatic electrolysis at a large current density (25mA·cm−2) was effective, and the Ag(I) ion concentration in the melt decreased to lower than 9ppm. Furthermore, the codeposit of Cu with the N included in the BPC, which was the main content in the bath was also examined. The electrodeposition of N was not recognized.
We developed an effective system to eliminate bacteria from modified tap water using a positively-charged carbon felt electrode. Particles with stronger negative charges are adsorbed more readily to a positively-charged carbon felt electrode. The zeta potential of bacteria suspended in modified tap water was measured by a microscopic electrophoresis method based on the electrophoretic mobility of bacteria particles. Bacteria electro-adsorption to the electrode was examined by bioassay. The mean zeta potential of the bacteria, Escherichia coli was −12mV, Staphylococcus aureus was −13mV, Bacillus subtilius spore was −20mV, and Saccharomyces cerevisiae was −7mV. E. coli, S. aureus, and B. subtilius spore were reduced with electrolytic current on their zeta potential conditions. But S. cerevisiae was almost eliminated at zero mA in modified tap water in spite of the smallest magnitude of its zeta potential. These results were considered using DLVO theory. S. cerevisiae had the property of a soft particle the same as blood erythrocyte. Therefore it may be that S. cerevisiae was adsorbed on the carbon electrode not only by electrostatic trapping, but also by specific adsorption between cells and carbon fibers. B. subtilius spore had the property of colloidal particles which can be treated with the DLVO theory. E. coli and S. aureus were at an intermediate level between S. cerevisiae and B. subtilius. It may be that the positively-charged carbon felt electrode effectively adsorbed various bacteria in water.