| 1. |
- Laxman, Karthik, et al.
(författare)
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Capacitive deionization with asymmetric electrodes: Electrode capacitance vs electrode surface area : Electrode capacitance vs electrode surface area
- 2015
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 176, s. 420-425
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Tidskriftsartikel (refereegranskat)abstract
- Asymmetry of electrodes on the equilibrium salt adsorption capacity in a capacitive configuration was studied. Experiments were carried out by using activated carbon cloth (ACC) with a specific surface area and specific capacitance of similar to 1000 m(2)/g and 44 F/g as the anode and ACC coated with zinc oxide nanorods (ZnO NR) with a specific surface area and specific capacitance of 637 m(2)/g and 57 F/g as the cathode. The electrodes were characterized electrically and their salt adsorption capacities measured for various anode-cathode configurations to conclude that for multimodal electrodes, specific capacitance and not specific surface area regulates the salt adsorption capacity. The adsorption trends were analyzed and equated to an electrical model to qualitatively predict the equilibrium salt adsorption capacity, where the smaller capacitance was observed to be the limiting factor. The results in this work are especially useful for practical CDI units, where anode-cathode capacitance should be matched to achieve maximum salt removal efficiency.
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| 2. |
- Laxman, Karthik, et al.
(författare)
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Desalination and disinfection of inland brackish ground water in a capacitive deionization cell using nanoporous activated carbon cloth electrodes
- 2015
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Ingår i: Desalination. - : Elsevier. - 0011-9164 .- 1873-4464. ; 362, s. 126-132
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Tidskriftsartikel (refereegranskat)abstract
- Desalination of brackish water using capacitive deionization (CDI) poses unique challenges attributed to the microbial, organic and other contaminants in water. By using chemically inert and high surface area activated carbon cloth electrodes, the desalination of water from wells in Oman's Al Musanaah wilayat is demonstrated. The ion adsorption characteristics for well water are compared to that of synthetic water (sodium chloride) and their dependence on the charge, size and concentration is investigated. Disinfection properties of the CDI unit were also demonstrated with a 3-fold decrease in viable bacterial cells upon desalination of well water. The power consumption for well water desalination was lower than that of synthetic water with similar salt concentrations and was calculated to be 0.78kWh/m3. The stated desalting capabilities and small footprint make CDI a viable option for remote ground water desalination.
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| 3. |
- Laxman, Karthik, et al.
(författare)
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Effect of a semiconductor dielectric coating on the salt adsorption capacity of a porous electrode in a capacitive deionization cell
- 2015
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 166, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical model was developed to study the effect of an additional dielectric coating on the conducting electrodes in a capacitive deionization cell. The electric field generated at the electrode surface and its distribution was quantitatively investigated for coating materials with different dielectric properties. The model shows that a nanostructured low dielectric and intrinsically polar material like zinc oxide (ZnO) is well suited to enhance the efficiency of capacitive desalination. Electrodes formed by ZnO nanorods coated on conducting electrodes of activated carbon cloth (ACC) were subsequently fabricated and its desalination parameters were studied using a 17 mM (1000 ppm) NaCl solution as the feed at an applied potential of 1.6 V DC. The composite ZnO nanorod coated electrodes improved salt removal efficiency by 40%, and adsorbed 35% of the salt in a single pass experiment, at a charge efficiency of 80% and an electrosorptive capacity of 8.1 mg/g of the electrode. A simultaneous increase in the ion adsorption rate led to a ∼40% reduction in the energy consumption as compared to an uncoated ACC electrode.
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| 4. |
- Laxman, Karthik, et al.
(författare)
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Improved desalination by zinc oxide nanorod induced electric field enhancement in capacitive deionization of brackish water
- 2015
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Ingår i: Desalination. - : Elsevier. - 0011-9164 .- 1873-4464. ; 359, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- Ion adsorption in capacitive deionization is a function of the electric field strength present at the electrode surface. We show enhancement in the electric field strength by coating activated carbon cloth (ACC) electrodes with zinc oxide (ZnO) nanorods, where the effective field was shown to vary with respect to the length, diameter and proximity of the coated ZnO nanorods. Deionization of a 17. mM NaCl solution in a single pass experiment using the composite electrodes showed a desalination efficiency of 35%, a 40% improvement as compared to plain ACC electrodes. The composite electrodes also desalinated at a charge efficiency of 78% with a salt uptake of 7.7. mg/g of the electrode. An enhancement in the ion adsorption rate led to a 30% reduction in the energy consumption per mole of salt removed for the desalination process. A theoretical model showing further enhancement in the desalination efficiency by reducing the diameter of the rods is also discussed.
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