No abstract

The influence of electrolyte flow velocity, concentration, and contact pressure on the anodic behavior of lithium at constant temperatures in LiOH was studied. The experimental results reveal that, under constant load polarization, a steady-state i-E curve is obtained consisting of resistance and concentration polarization components. A method to accurately determine the film thickness was devised. It was found that the oxide film at the anode surface is quite thick, ca. 10 -2 cm, and its thickness remained constant irrespective of polarization level at constant electrolyte concentration, flow rate, and anode-cathode contact pressure. The effective diffusion layer at the Li active surface is thin, ca. 10 -3 cm. The fraction of active surface area was found to change significantly with LiOH concentration (ranging from 0.05 in 4.84M to 0.39 in 2.9UM), but it was virtually independent of flow velocity and contact pressure. Likewise, electrolyte concentration has far greater influence on film resistance than flow rate or contact pressure. Electrolyte flow velocity variation is, however, an effective means to alter power output from the cell. The oxide/hydroxide film which forms on Li anodes in aqueous, strongly alkaline electrolytes has some tmusual properties. For example, even though it is fairly thick (ca. 5 X 10 -2 cm) it will support high * Electrochemical Society Active Member.

Experimental results are presented for the anodic oxidation of ferrous iron in dilute ferrous sulfate-sulfuric acid solutions. A conductive fixed-bed, flowthrough, electrochemical reactor in which electric current flow is parallel to the direction of electrolytic solution flow was used. Steady-state anodic polarization curves were obtained at seven different flow rates, ranging from 1.5 to 10 ml/min in a cell of 81.1 cm 2 cross section. Input ferrous iron concentrations were 725 ~g/ml in an acid mine water simulant containing 1430 ~g/ml of sulfuric acid. Conversion efficiency for ferrous to ferric iron exceeded 99.9% at the lower flow rates. Design equations have been developed which predict performance of the system. Measured limiting currents exceed theoretical values by 6-14%. A preliminary cost analysis for a million gallons per day acid mine water treatment plant for oxidizing ferrous to ferric iron using parallel current-electrolytic solution flows predicts 7.5r per thousand gallons of which 4.6r per thousand gallons is assigned to capital costs. An additional 22.3r per thousand gallons must be added for following limestone treatment and precipitation of the ferric iron. * Electrochemical Society Active Member. both appear to rule out present use of most of these approaches. The principal treatment now in use commercially is the lime neutralization with aeration process.An alternate approach is to preoxidize the ferrous ion electrolytically with subsequent iron precipitation and acid neutralization effected by addition of ground limestone. Certain economic advantages are claimed for this approach over the lime neutralization with ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-26 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.120.3 Downloaded on 2015-05-26 to IP

No abstract