Activated carbon nanofiber webs made by electrospinning for capacitive deionization

Wang, Gang; Pan, Chao; Wang, Liuping; Dong, Qiang; Yu, Chang; Zhao, Zongbin

doi:10.1016/j.electacta.2012.02.066

Cited by 337 publications

(157 citation statements)

References 30 publications

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“…In commercial desalination technologies, such as reverse osmosis and multistage flash distillation, freshwater is produced at relatively high energy cost and often requires re-mineralization for human consumption. For brackish water or wastewater it can be advantageous to use a different type of technology, namely techniques where ions are removed from the feed water under the influence of electrical field effects, such as in electrodialysis [8,9], capacitive deionization [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], membrane capacitive deionization [29][30][31][32][33][34], desalination using microchannels [35], batteries [36], microbial desalination cells [37] and wires [38]. Such techniques have the potential to be energy-efficient as they focus on the removal of the (often relatively few) ions in the water to obtain freshwater in this way.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent ion selectivity in capacitive charging of porous electrodes

Zhao

Soestbergen

Rijnaarts

et al. 2012

Journal of Colloid and Interface Science

227

182

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In a combined experimental and theoretical study we show that capacitive charging of porous electrodes in multicomponent electrolytes may lead to the phenomenon of time-dependent ion selectivity of the electrical double layers (EDLs) in the electrodes. This effect is found in experiments on capacitive deionization of water containing NaCl/CaCl 2 mixtures, when the concentration of Na + ions in the water is 5 times higher than the Ca 2+ -ion concentration. In this experiment, after applying a voltage difference between two porous carbon electrodes, first the majority monovalent Na + cations are preferentially adsorbed in the EDLs, and later they are gradually replaced by the minority, divalent Ca 2+ cations. In a process where this ion adsorption step is followed by washing the electrode with freshwater under open-circuit conditions, and subsequent release of the ions while the cell is shortcircuited, a product stream is obtained which is significantly enriched in divalent ions. Repeating this process three times by taking the product concentrations of one run as the feed concentrations for the next, a final increase in the Ca 2+ /Na + -ratio of a factor of 300 is achieved. The phenomenon of timedependent ion selectivity of EDLs cannot be explained by linear response theory. Therefore, a nonlinear time-dependent analysis of capacitive charging is performed for both porous and flat electrodes. Both models attribute time-dependent ion selectivity to the interplay of the transport resistance for the ions in the aqueous solution outside the EDL, and the voltage-dependent ion adsorption capacity of the EDLs. Exact analytical expressions are presented for the excess ion adsorption in planar EDLs (Gouy-Chapman theory) for mixtures containing both monovalent and divalent cations.key-words: water desalination; porous electrode theory; capacitive (non-faradaic) electrochemical cells; electrostatic double layer theory.2

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Section: Introductionmentioning

confidence: 99%

Time-dependent ion selectivity in capacitive charging of porous electrodes

Zhao

Soestbergen

Rijnaarts

et al. 2012

Journal of Colloid and Interface Science

227

182

View full text Add to dashboard Cite

show abstract

“…These results imply that at low potential scan rates, the electrolytes have sufficient time to accumulate and arrange on the surface, which significantly contributes to the formation of the double-layer capacitance [49]. Therefore, the electrosorption deionization becomes more efficient [47].…”

Section: Capacitive Deionization Performancementioning

confidence: 83%

“…In general, cyclic voltammetry (CV) is employed to evaluate the potential of the materials used for CDI, and the specific capacitance can be calculated accordingly [16,47]. Figure 9 displays the CV results for an electrode (typically, a single electrode is used for all measurements), which was made of the introduced nanoparticles at different NaCl concentrations (0.1, 0.5 and 1.0 M) at selected scan rates from 10 to 1000 mV/s.…”

Section: Capacitive Deionization Performancementioning

confidence: 99%

Development of Cd-doped Co Nanoparticles Encapsulated in Graphite Shell as Novel Electrode Material for the Capacitive Deionization Technology

et al. 2013

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Because of the low energy requirement and the environmentally safe byproducts, the capacitive deionization water desalination technology has attracted the attention of many researchers. The important requirements for electrode materials are good electrical conductivity, high surface area, good chemical stability and high specific capacitance. In this study, metallic nanoparticles that are encapsulated in a graphite shell (Cd-doped Co/C NPs) are introduced as the new electrode material for the capacitive deionization process because they have higher specific capacitance than the pristine carbonaceous materials. Cd-doped Co/C NPs perform better than graphene and the activated carbon. The introduced nanoparticles were synthesized using a simple sol-gel technique. A typical sol-gel composed of cadmium acetate, cobalt acetate and poly(vinyl alcohol) was prepared based on the polycondensation property of the acetates. The physiochemical characterizations that were used confirmed that the drying, grinding and calcination in an Ar atmosphere of the prepared gel produced the Cd-doped Co nanoparticles, which were encapsulated in a thin graphite layer. Overall, the present study suggests a new method to effectively use the encapsulated bimetallic nanostructures in the capacitive deionization technology.

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“…Despite activated carbon being widely studied as a material for CDI electrodes (Bouhadana et al, 2011;Choi, 2010;Hou and Huang, 2013;Hou et al, 2012;Huang et al, 2012;Mossad and Zou, 2012;Porada et al, 2012;Villar et al, 2010;Wang et al, 2012;Wang et al, 2013), one of the drawbacks associated with its use is the requirement for a polymeric binder. Typically hydrophobic polymers such as poly(tetrafluoroethylene) (PTFE) (Chang et al, 2012;Lee et al, 2009) or poly(vinylidene fluoride) (PVDF) (Zhang et al, 2012) are used to bind activated carbon powder.…”

Section: Introductionmentioning

confidence: 99%