Effects of electrolyte viscosity on the efficiency of the electrochemical removal of lead ions using porous flow-through electrodes

The current study addresses the effect of the electrolyte viscosity on the efficiency of porous flow-through electrode [PFTE] made up of stacked screens during the electrochemical removal of lead ions from flowing alkaline solutions. Two types of efficiencies characterize the overall behaviour of the PFTE, namely, the collection efficiency [ratio of the captured ions to the feed concentration] and the coulombic efficiency [percentage of the total current used for the electrodeposition of lead ions]. The increase in the electrolyte viscosity causes a decrease in the experimentally measured limiting current of the electrodeposition reaction at the same electrolyte flow rate, and hence the collection efficiency decreases correspondingly. Also, the coulombic efficiency decreases with the increase of the electrolyte viscosity. This is attributed to the consequences of decreasing the diffusivity and the interfacial mass transfer coefficient of lead ions with the increase of electrolyte viscosity. On the other hand, the conductivity of the electrolyte has no effect on the limiting current

Electrochemical behaviour of copper in alcoholic media: effect of bromoacetanilide as chelating agent

Galvanostatic anodic and cathodic polarizations were obtained for Polycrystalline copper electrodes in solutions of 50 percent [v/v] ethanol-water mixture. The open circuit potential and the anodic dissolution of copper were investigated both in absence and in presence of bromoacetoacetanilide [gamma-B[r]-A.A.A.] ligand over a range of concentration and pH values. The presence of the ligand in variably shifted the open circuit potential in the cathodic direction due to the formation of a [1:1] complex. The anodic dissolution of copper was found to follow a stepwise mechanism where the overall rate is diffusion controlled. The exchange current density increases with increasing ligand concentration. The cathodic deposition of copper from solutions of copper gamma-Br-A.A.A. [1:2] complex was also found to follow a stepwise mechanism where the electron transfer step Cu [++] + e ->Cu [+] is rate limiting. At high current density the rate of deposition is controlled by both activation and mass transfer