The electrochemical reduction of nickel ions from a dilute solution has been carried out in a gas diffusion electrode packed bed electrode cell (GBC). Particle size and electrode configuration have been found to have a significant influence on the reduction process. Electrodes with a high porosity and large pores have been found to be the best for nickel deposition. The nickel current efficiency, Ni, is reported to be dependent on the current density, volumetric flow rate, nickel and boric acid concentration, and the pH. The fall in the nickel current efficiency is caused by an increase in electrode surface pH above a certain level, caused by either high bulk solution pH or high current density, leading to possibly formation of Ni(OH)2. It has been found that under conditions of exclusively metallic nickel deposition Ni/(1–Ni) is proportional to i0.69,Q10.52,CNi0.67,CBA–0.19 and pH1.0. 相似文献
The water sorption and diffusion in (reduced) graphene oxide‐alginate composites of various compositions is analyzed. Water sorption of sodium alginate can be significantly reduced by the inclusion of graphene oxide sheets due to the formation of an extensive hydrogen bonding network between oxygenated groups. Crosslinking alginate with divalent metal ions and the presence of reduced graphene oxide can further improve the swelling resistance due to the strong interactions between metal ions, alginate, and filler sheets. Depending on conditions and composition, the overall water barrier properties of alginate composites improve upon (reduced) graphene oxide filling, making them attractive for moisture barrier coating applications. Water sorption kinetics in all alginate composites indicate a non‐Fickian diffusion process that can be accurately described by the Variable Surface Concentration model. In addition, the water barrier properties of sodium alginate‐graphene oxide composites can be adequately predicted using a simple model that takes the orientational order of filler sheets and their effective aspect ratio into account.