PDF Publication Title:
Text from PDF Page: 005
Langmuir Article Figure 5. Observation of overlimiting current in aqueous CuSO4. (a) For 1.0 M concentration, the current−voltage curve is compared to the classical diffusion-limited model (eq 1), the extension for OLC by surface transport (eq 3), and its correction for electrode resistance (eq 8). (b) Current−voltage data for varying initial ion concentrations with fitted curves based on the new model. (c) Dimensionless voltage−current curves with an inset showing the data collapse at lower voltages. The bottom row presents the scaling of the fitting parameters with salt concentration c0 (blue points): (d) limiting current Ilim, (e) series resistance Rs, and (f) overlimiting conductance σOLC compared to theoretical curves (solid colors) and scalings (slopes) discussed in the text. ■ RESULTS Current−Voltage Relation. A typical voltammogram is shown in Figure 5a (black curve) for c0 = 1 M. As in all prior Figure 6. Effect of surface charge modification. Linear sweep voltammetry at 2 mV/s for 1 mM aqueous CuSO4 solution in the same apparatus above is shown for negatively charged bare silica and two positively charged surfaces, obtained by silanization and polymer deposition. Dashed curves indicate the data, and solid lines indicate the fit to the theory (eqs 3 and 8). experiments with ion-exchange membranes10 and microfluidic devices,17,21,23 the classical diffusion-limited behavior of eq 1 (gray line in Figure 5), which has no free parameters and saturates at the thermal voltage kBT/e = 26 mV, does not match the data. In our experiment, we resolve this discrepancy by accounting for the electrode and reservoir polarization. A series resistance, Rs, is fitted to the low-voltage portion of each voltammogram by replacing the applied voltage, Vapp, with V=V −IR app s (8) in eq 1, as in the blue curve in Figure 5a. From the experiments we are thus able to infer the electrokinetic response of the glass frit, which can be separated from all the other internal resistances by examining the scalings of Ilim, Rs, and σOLC with salt concentration and surface charge. After correcting for electrode polarization, the theoretical prediction of eq 3 provides a good fit of the data (red line in Figure 5a). By least-squares fitting of only three parameters (Ilim, Rs, and σOLC) for each quasi-steady voltammogram, the coefficient of determination is 99% over a wide range of salt concentrations (Figure 5b). The limiting current from the fitting for 1 M concentration is about 6.8 mA, and the membrane working area is the same as the cross-sectional area of the glass frit, resulting in a calculated limiting current density of approximately 8.6 mA/cm2. As shown in Figure 5c, the dimensionless current, Ĩ = I/Ilim, versus voltage, Ṽ = zeV/kBT (z = 2), collapses onto a single master curve, eq 1, at low voltage (inset) while displaying a nearly constant overlimiting conductance, consistent with the theory.12 For the lowest salt concentration (10−4 M), a nonconstant overlimiting con- ductance could also be related to additional ion transport from the dissociation of water or dissolved CO2 in the solution, but transient diffusion is the more likely cause of the observed weak oscillations around the mean linear profile of OLC at all salt concentrations, as discussed above and in the Supporting Information. Limiting Current. To the best of our knowledge, this is the first quantitative fit of experimental data by OLC theory by any mechanism. To check our assumptions and identify the physical mechanism for OLC, the scalings of Ilim, Rs, and σOLC are investigated with respect to the concentration of CuSO4 over 4 orders of magnitude, from 0.1 mM to 1.0 M. The error in each 16171 dx.doi.org/10.1021/la4040547 | Langmuir 2013, 29, 16167−16177PDF Image | Overlimiting Current and Shock Electrodialysis in Porous Media
PDF Search Title:
Overlimiting Current and Shock Electrodialysis in Porous MediaOriginal File Name Searched:
02_Deng_Langmuir2013.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)