A study of electrosorption selectivity of anions by activated carbon electrodes in capacitive deionization

Chen, Zhaolin; Zhang, Hongtao; Wu, Chunxu; Wang, Yushuang; Li, Wei

doi:10.1016/j.desal.2015.04.022

Cited by 146 publications

(71 citation statements)

References 28 publications

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“…Once these ions have been recovered, the stronger sorption capacity of NO3allows it to replace the Cland SO4 2ions. Chen et al (Chen et al 2015) investigated the competitive electrosorption of mixed Cland NO3and mixed Cland SO4 2solutions and reported a similar ion substitution phenomenon for NO3 -. They compared this behavior to ion exchange processes in which NO3 -334 is similarly selectively adsorbed relative to Cl -.…”

Section: Feed Solutions Containing a Salt Mixturementioning

confidence: 89%

A comparison of multicomponent electrosorption in capacitive deionization and membrane capacitive deionization

et al. 2018

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In this study, the desalination performance of Capacitive Deionization (CDI) and Membrane Capacitive Deionization (MCDI) was studied for a wide range of salt compositions. The comprehensive data collection for monovalent and divalent ions used in this work enabled us to understand better the competitive electrosorption of these ions both with and without ion-exchange membranes (IEMs). As expected, MCDI showed an enhanced salt adsorption and charge efficiency in comparison with CDI. However, the different electrosorption behavior of the former reveals that ion transport through the IEMs is a significant rate-controlling step in the desalination process. A sharper desorption peak is observed for divalent ions in MCDI, which can be attributed to a portion of these ions being temporarily stored within the IEMs, thus they are the first to leave the cell upon discharge. In addition to salt concentration, we monitored the pH of the effluent stream in CDI and MCDI and discuss the potential causes of these fluctuations. The dramatic pH change over one adsorption and desorption cycle in CDI (pH range of 3.5-10.5) can be problematic in a feed water containing components prone to scaling. The pH change, however, was much more limited in the case of MCDI for all salts.

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Section: Feed Solutions Containing a Salt Mixturementioning

confidence: 89%

A comparison of multicomponent electrosorption in capacitive deionization and membrane capacitive deionization

et al. 2018

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“…Several literatures that worked on competitive electrosorption reported that the electrosroption selectivity is firstly determined by initial concentration of feed, then ionic charge valency, and hydrated radius of ions [37,38]. First, the carbon electrodes preferentially hold the high concentration ions.…”

Section: Ion Discharge From Carbon Electrodesmentioning

confidence: 99%

Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater

Kim

Dorji

Gwak

et al. 2019

ACS Sustainable Chem. Eng.

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The ion desorption behavior from carbon electrodes onto high concentration brine was examined in this work because the ionic resources in brine are accumulated to attain high concentration in membrane capacitive deionization (MCDI) during mineral resource recovery. Several major issues were explored to demonstrate the suitability of MCDI for mineral recovery: ion discharge behavior using different solution chemistries (0 to 10 mM of NaCl, KCl, and MgCl2) of feed and brine, desorption efficiencies of various electrode regeneration methods (reverse polarity, short-circuiting and power disconnection) for enrichment of ions, and ion desorption selectivity among selected cations (Na, K, and Mg). The desorption efficiency was inversely proportional to ionic strength of aqueous brine solution as the ions from electrodes migrate toward the brine solution against ionic-strength gradient. Furthermore, the desorption onto brine was constrained by utilizing energy-efficient short-circuiting, whereas the electrochemically adsorbed ions were well discharged by reversing the polarity compensating for its cost. The ions were preferentially released from the electrodes in order of Na>K>Mg in the results, showing a reverse trend with the selectivity of electrosorption. From ammonium recovery tests, a high concentration of ammonium in brine (78.54 mg/L) was obtained from the synthetic wastewater through continuous operation of five cycles, attributing to its selective desorption over sodium ions present. However, it must be noted that its incomplete discharge from the electrodes is a challenging issue to overcome the limitations of MCDI as a mineral recovery process, and to attain highly concentrated ammonium.

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“…Chen et al investigated the phosphate uptake capacity via electro-sorption and the effect of other anions (i.e. Cl − , NO 3− and SO4 2− ) on the electro-sorption performance; this work provides a better understanding of ion selectivity in mixed electrolyte solutions [38]. Recently, Huang et al were the first investigated the pH-dependent phosphate removal from wastewaters by electrosorption deionization at two operational modes (constant voltage and constant current) [36].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Enhanced phosphate removal under an electric field via multiple mechanisms on MgAl-LDHs/AC composite electrode

Hong

Zhu

et al. 2019

Journal of Electroanalytical Chemistry

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Phosphorus removal is essential to avoid eutrophication in water bodies. Layered double hydroxides (LDHs) are widely used to scavenge phosphate through intercalated ion exchange or surface complexation. Moreover, LDHs have attracted increasing attention as electrode modifiers for supercapacitors. Researchers have begun to re-delve the electrosorption technology according to the fundamental principle of electrical double layers. Herein, we propose a new phosphate removal method inspired by the adsorption characteristic and electrical double-layer capacitive properties of LDHs through electrosorption via capacitive deionization. We present a series of experiments to study the enhanced phosphate removal under an electric field via multiple mechanisms on the MgAl-LDHs/AC electrode. The uptake of phosphate by MgAl-LDHs/AC was investigated as a function of phosphate concentration, applied voltage, electrode materials, and temperature. The MgAl-LDHs/AC electrode possessed a salt removal capacity of 67.92 mg PO4 3-•g-1 (1.2 V, 250 mg•L-1 KH2PO4, 30 °C). The electrosorption kinetics of phosphate ions onto the capacitive deionization electrode followed the pseudo-second-order kinetics model rather than the pseudo-first-order kinetics model. Furthermore, the adsorption isotherms of phosphate on the MgAl-LDHs/AC electrode fitted the Freundlich model better than the Langmuir model. The proposed method could be used for phosphate removal.

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A study of electrosorption selectivity of anions by activated carbon electrodes in capacitive deionization

Cited by 146 publications

References 28 publications

A comparison of multicomponent electrosorption in capacitive deionization and membrane capacitive deionization

A comparison of multicomponent electrosorption in capacitive deionization and membrane capacitive deionization

Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater

Enhanced phosphate removal under an electric field via multiple mechanisms on MgAl-LDHs/AC composite electrode

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