Effects of characteristics of cation exchange membrane on desalination performance of membrane capacitive deionization

Yoon, Hai Jeon; Jo, Kyusik; Kim, Kwang Je; Yoon, Jeyong

doi:10.1016/j.desal.2019.02.009

Cited by 25 publications

(13 citation statements)

References 34 publications

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“…In this work, we test the latter hypothesis by employing CB suspensions to replace the typical AC suspension as the flow electrodes. Normally applied as an electron-conductive agent in the CDI film electrode, − CB is a material of high bulk conductivity with large facial ion-accessible specific surface areas and is cost-effective as compared with other carbon conductive additives, such as graphene and carbon nanotubes . When charged, target ions can insert into the bent layers of CB and then adsorb onto the external surface, and therefore the ion diffusion path is shortened .…”

Section: Introductionmentioning

confidence: 99%

Carbon Black Flow Electrode Enhanced Electrochemical Desalination Using Single-Cycle Operation

Zhang

Yang

et al. 2019

Environ. Sci. Technol.

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Flow-electrode electrochemical desalination (FEED) processes (e.g., flow-electrode capacitive deionization), which use flowable carbon particles as the electrodes, have attracted increasing attention, holding the promise for continuous desalination and high desalting efficiency. While it is generally believed that carbon particles with abundant microporous and large specific capacitances (e.g., activated carbon, AC) should be ideal candidates for FEED electrodes, we provide evidence to the contrary, showing that highly conductive electrodes with low specific surface area can outperform microporous AC-based electrodes. This study revealed that FEED using solely high surface area AC particles (∼2000 m 2 g −1 , specific capacitance of ∼44 F g −1 , average salt adsorption rate of ∼0.15 μmol cm −2 min −1 ) was vastly outperformed by electrodes based solely on low-surface area carbon black (CB, ∼70 m 2 g −1 , ∼0.5 F g −1 , ∼0.75 μmol cm −2 min −1 ). Electrochemical impedance spectroscopy results suggest that the electrode formed by CB particles led to more effective electronic charge percolation, likely contributing to the improved desalination performance. In addition, we propose and demonstrate a novel operation mode, termed single cycle (SC), which greatly simplified the FEED cell configuration and enabled simultaneous charging and discharging. Using SC mode with CB flow electrodes delivered an increased average salt removal rate relative to the more traditional short-circuited closed cycle (SCC) mode, achieving up to 1.13 μmol cm −2 min −1 . Further investigations demonstrate that up to 50% of energy input would be avoided when using CB flow electrodes operated under SC mode as compared to that of AC flow electrodes operated under SCC mode. In summary, the FEED process presented in this study provided an innovative and promising approach toward high-efficient and low-cost brackish water desalination.

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Section: Introductionmentioning

confidence: 99%

Carbon Black Flow Electrode Enhanced Electrochemical Desalination Using Single-Cycle Operation

Zhang

Yang

et al. 2019

Environ. Sci. Technol.

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“…The Λ values for CMX and CMX-PEM membranes were around 69%, showing that the addition of PEM has no significant effect on Λ. These values are slightly lower than those for CMX reported in the literature (88 ± 5%), 77 which can be associated with the type of the carbon electrode and the cell design. Furthermore, since we did not have a single-salt solution, ICP-OES data were used to calculate the amounts of salt removed.…”

Section: Resultsmentioning

confidence: 58%

“…The η values observed during the electrosorption process were comparable with the literature values. 77 , 78 …”

Section: Resultsmentioning

confidence: 99%

Modification of Cation-Exchange Membranes with Polyelectrolyte Multilayers to Tune Ion Selectivity in Capacitive Deionization

Şahin

Dykstra

Zuilhof

et al. 2020

ACS Appl. Mater. Interfaces

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Capacitive deionization (CDI) is a desalination technique that can be applied for the separation of target ions from water streams. For instance, mono- and divalent cation selectivities were studied by other research groups in the context of water softening. Another focus is on removing Na + from recirculated irrigation water (IW) in greenhouses, aiming to maintain nutrients. This is important as an excess of Na + has toxic effects on plant growth by decreasing the uptake of other nutrients. In this study, we investigated the selective separation of sodium (Na + ) and magnesium (Mg 2+ ) in MCDI using a polyelectrolyte multilayer (PEM) on a standard grade cation-exchange membrane (Neosepta, CMX). Alternating layers of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were coated on a CMX membrane (CMX-PEM) using the layer-by-layer (LbL) technique. The layer formation was examined with X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements (SWA) for each layer. For each membrane, i.e., the CMX-PEM membrane, CMX membrane, and for a special-grade cation-exchange membrane (Neosepta, CIMS), the Na + /Mg 2+ selectivity was investigated by performing MCDI experiments, and selectivity values of 2.8 ± 0.2, 0.5 ± 0.04, and 0.4 ± 0.1 were found, respectively, over up to 40 cycles. These selectivity values indicate flexible switching from a Mg 2+ -selective membrane to a Na + -selective membrane by straightforward modification with a PEM. We anticipate that our modular functionalization method may facilitate the further development of ion-selective membranes and electrodes.

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“…The average values of SAC were statistically analyzed by t-test. ASAR was obtained using Equation (2) [34]:…”

Section: Desalination Experimentsmentioning

confidence: 99%

Effect of Hydrophilicity of Activated Carbon Electrodes on Desalination Performance in Membrane Capacitive Deionization

Baek

Lee

et al. 2019

Applied Sciences

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Membrane capacitive deionization (MCDI) is a modification of capacitive deionization (CDI) using ion-exchange membranes (IEM) in front of the electrodes. Electrode properties, especially the specific surface area, are known to be strongly related with desalination performance in CDI, but the effects of other properties in MCDI are not fully understood. The objective of this study was to investigate the effect of hydrophilicity in activated carbon electrodes on desalination performance in MCDI. Two types of activated carbon (P60 and YS-2) whose specific surface areas were similar were used as electrode materials, but they had different hydrophilicity (i.e., P60 was originally hydrophobic and YS-2 was relatively hydrophilic due to its nitrogen-containing surface chemistry). These hydrophilic electrodes (either the electrode itself or modified with polydopamine (PDA)) led to an increase in the salt adsorption capacity (SAC) in MCDI because they facilitated the access of both ions and water molecules into the electrode pores. In particular, the SAC of the P60 electrode displayed a large increase to almost reach that of the YS-2 electrode due to the improved hydrophilicity with PDA modification and the insignificant effects of PDA modification on an already hydrophilic YS-2 electrode. Additionally, PDA-modified IEM in MCDI reduced the SAC as a result of the additional insulating PDA layer with little changes in hydrophilicity.

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Effects of characteristics of cation exchange membrane on desalination performance of membrane capacitive deionization

Cited by 25 publications

References 34 publications

Carbon Black Flow Electrode Enhanced Electrochemical Desalination Using Single-Cycle Operation

Carbon Black Flow Electrode Enhanced Electrochemical Desalination Using Single-Cycle Operation

Modification of Cation-Exchange Membranes with Polyelectrolyte Multilayers to Tune Ion Selectivity in Capacitive Deionization

Effect of Hydrophilicity of Activated Carbon Electrodes on Desalination Performance in Membrane Capacitive Deionization

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