The Feasibility of Energy Extraction from Acidic Wastewater by Capacitive Mixing with a Molecular‐Sieving Carbon Electrode

Shapira, Barak; Avraham, Eran; Aurbach, Doron

doi:10.1002/cssc.201601300

Cited by 10 publications

(9 citation statements)

References 36 publications

(55 reference statements)

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“…At relative negative potentials, the differential capacitance is significantly higher than that at the positive potentials. This result is in agreement with our previous research, 14,18 where we showed that very short exposure of pristine carbon paper to HNO 3 (less than 15 minutes at room temperature) is insufficient for the development of an accessible porous structure toward sodium electroadsorption whereas, after 30 minutes of exposure, the porous structure enables the accommodation of both sodium and chloride ions (but at different ratios). Here, an intermediate exposure time was used.…”

Section: Methodssupporting

confidence: 93%

“…Capacitive mixing [7][8][9][10][11][12][13][14][15] (CAPMIX), first proposed by Brogioly, 16 is a membrane-free technique. In general, the energy extraction is based on potential differences developed as a result of double-layer (i.e., electrostatic) interactions between high-surface-area electrodes through which solutions of different NaCl concentrations flow.…”

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confidence: 99%

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Anion-Exclusion Carbon Electrodes for Energy Storage and Conversion by Capacitive Mixing

Shapira

Cohen

Avraham

et al. 2017

J. Electrochem. Soc.

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Capacitive mixing is a newly emerging technique for the production of renewable energy from the controlled mixing of river water and seawater. Energy extraction is provided by the potential rise in electrodes held in a fixed charge, as a response to the concentration change. Therefore, electrodes that exhibit high potential variation as a response to concentration change (negative rise for the cation-capturing electrode and vice versa) are highly desirable. In this work, electrodes that can accommodate mostly cations within their porous structure are discussed. In accordance to the modified Donnan (mD) model of the electrical double layer, it is expected that such electrodes will display the highest potential change as a response to concentration change (while being held with a fixed charge). Using appropriate selective activated carbon electrodes, high potential rise, around 50 mV, was observed as a response to concentration change, when the concentration of NaCl solutions was changed from 1M to 10 −1 M and from 10 −1 M to 10 −2 M. Such a capability of potential rise of selective electrodes can serve as a good basis for energy extraction by capacitive mixing. The energy that dissipates due to the mixing of two solutions with different salt concentrations, such as seawater and river water, can be, in fact, partially harvested by controlled mixing. The upper limit of energy that can be obtained from mixing two ideal solutions with different concentrations is given by the Gibbs free energy of mixing. 1For example, the maximum energy that can be obtained from mixing 1 Liter of seawater and 1 Liter of river water is about 2 kJ. There are several methods for energy extraction by controlled mixing of seawater and river water, including pressure-retarded osmosis (PRO), 2 reversed electro-dialysis (RED) 3,4 and vapor-pressure difference utilization.5 Recently, energy extraction from salinity difference by swelling and shrinking of hydrogels has been suggested. 6 However, to the best of our knowledge, these methods have to be proven as commercially viable.Capacitive mixing 7-15 (CAPMIX), first proposed by Brogioly, 16 is a membrane-free technique. In general, the energy extraction is based on potential differences developed as a result of double-layer (i.e., electrostatic) interactions between high-surface-area electrodes through which solutions of different NaCl concentrations flow. In principle, the exchange between two bulk solutions with different salinities that are in contact with two charged high-surface-area electrodes leads to changes in their capacitance and, consequently, in the potential of the electrochemical cell utilizing them:where V [V] is the electrodes-potential difference [i.e., the sum, in absolute values, of the electrical double layer (EDL)-related potentials of both the cation-and the anion-capturing electrodes], Q [C] is the total charge of the electrodes (equal but with opposite signs) and C [F] is the change in capacitance resulting from the mixing. A decrease in cell potential (for a cell with...

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Section: Methodssupporting

confidence: 93%

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confidence: 99%

Anion-Exclusion Carbon Electrodes for Energy Storage and Conversion by Capacitive Mixing

Shapira

Cohen

Avraham

et al. 2017

J. Electrochem. Soc.

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“…Na H    ), and in other cases exhibit selectivity based on ion shape. 25,26 These phenomena may be due to strong ion-wall interactions attributed to the extremely small size of the micropores. Fourth, as our model follows a mean-field approach, it does not capture local ionion interactions in the micropore, which may affect the predicted micropore concentration and EDL selectivity.…”

Section: /0mentioning

confidence: 99%

“…A promising feature of CDI electrodes is their demonstrated ability to preferentially electrosorb specific counterions from a feedstream with multiple counterionic species. For example, CDI electrodes have demonstrated selective electrosorption based on ion valence, 22 size, [23][24][25] and shape. 26 Selectivity is a desirable feature in water treatment, in particular for removing ionic contaminants from ground or wastewaters.…”

Section: Introductionmentioning

confidence: 99%

Size-Based Ion Selectivity of Micropore Electric Double Layers in Capacitive Deionization Electrodes

Suss

2017

J. Electrochem. Soc.

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Capacitive deionization (CDI) is a fast-emerging technology most commonly applied to brackish water desalination. In CDI, salt ions are removed from the feedwater and stored in electric double layers (EDLs) within micropores of electrically charged porous carbon electrodes. Recent experiments have demonstrated that CDI electrodes exhibit selective ion removal based on ion size, with the smaller ion being preferentially removed in the case of equal-valence ions. However, state-of-the-art CDI theory does not capture this observed selectivity, as it assumes volume-less point ions in the micropore EDLs. We here present a theory which includes multiple couterionic species, and relaxes the point ion assumption by incorporating ion volume exclusion interactions into a description of the micropore EDLs. The developed model is a coupled set of nonlinear algebraic equations which can be solved for micropore ion concentrations and electrode Donnan potential at cell equilibrium. We demonstrate that this model captures key features of the experimentally observed size-based ion selectivity of CDI electrodes.

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“…24 The structures of H 2 BDC-IPO were confirmed by 1 H NMR (Figure S1). 1 H NMR spectra of the compounds in dimethyl sulfoxide were obtained with a BRUKER spectrometer. Then, UiO-66-IPO was prepared based on a modified procedure reported in the literature.…”

Section: Methodsmentioning

confidence: 99%

Novel Isopropoxy Group-Functionalized UiO-66 with a High Hydrogen Chloride Adsorption Capacity

Liu

Bai

et al. 2019

J. Chem. Eng. Data

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In this paper, a novel isopropoxy group-functionalized UiO-66 (UiO-66-IPO) was synthesized by a general strategy and then used as an adsorbent for the removal of hydrogen chloride from aqueous solutions. The as-synthesized product was characterized by X-ray powder diffraction, scanning electron microscopy, thermal gravimetric analysis, N2 adsorption and desorption isotherms, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The adsorbent showed a much higher adsorption capacity of 429.68 mg·g–1 under the initial condition of 1.4 mol·L–1 HCl concentration at 25 °C within a relatively short time (4 h). Adsorption kinetics, isotherms, thermodynamics, regeneration, and the mechanism of hydrogen chloride adsorption on the adsorbent were studied. The results showed that the hydrogen chloride adsorption process reached equilibrium quickly in 4 h, and the adsorption kinetics on UiO-66-IPO was well-described by the pseudo-second-order model. Meanwhile, the Henry isotherm and Freundlich isotherm fitted the experiment data well. The thermodynamic parameters, such as ΔG, ΔH, and ΔS, were determined, and the results indicated that the adsorption process was spontaneously exothermic and entropy decreasing. XPS and FT-IR were conducted to explore the hydrogen chloride adsorption mechanism. The regeneration experiments demonstrated that UiO-66-IPO still exhibited excellent adsorption performance on hydrogen chloride after three cycles.

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The Feasibility of Energy Extraction from Acidic Wastewater by Capacitive Mixing with a Molecular‐Sieving Carbon Electrode

Cited by 10 publications

References 36 publications

Anion-Exclusion Carbon Electrodes for Energy Storage and Conversion by Capacitive Mixing

Anion-Exclusion Carbon Electrodes for Energy Storage and Conversion by Capacitive Mixing

Size-Based Ion Selectivity of Micropore Electric Double Layers in Capacitive Deionization Electrodes

Novel Isopropoxy Group-Functionalized UiO-66 with a High Hydrogen Chloride Adsorption Capacity

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