Optimization of the voltage window for long-term capacitive deionization stability

Lu, Doukun; Cai, Wangfeng; Wang, Yan

doi:10.1016/j.desal.2017.09.026

Cited by 75 publications

(31 citation statements)

References 55 publications

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“…[29] Different approaches have been employed to adjust the chemicalc harge, including electrochemical and chemical treatment of the electrode material [30] and the addition of conducting polymers with tailoredsurface charges. [31] In this work, we introduce lignin-derived activation carbon as an attractive electrode material for CDI and demonstrate the importance of an asymmetrice lectrode configuration to optimize the performance and the long-term operation stability.T he first approachf or the asymmetric configuration varies the electrode thickness to reduce the potential of the positive electrode. Thereby,w ed iscuss the potential distribution of the individual electrodes, the shift in the potentialo fz ero charge, and the resulting performance stability.T he second approach adopts carbon electrode materials with different E PZC valuest o minimize co-ion expulsion and electrode oxidation on the positive electrode.…”

Section: Introductionmentioning

confidence: 99%

“…The presence of chemical charges may shift the potential of zero charge ( E PZC ) of the electrode, causing co‐ion expulsion and, consequently, reduce the ion removal capacity of the electrodes . Different approaches have been employed to adjust the chemical charge, including electrochemical and chemical treatment of the electrode material and the addition of conducting polymers with tailored surface charges …”

Section: Introductionmentioning

confidence: 99%

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Charge and Potential Balancing for Optimized Capacitive Deionization Using Lignin‐Derived, Low‐Cost Activated Carbon Electrodes

et al. 2018

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Lignin-derived carbon is introduced as a promising electrode material for water desalination by using capacitive deionization (CDI). Lignin is a low-cost precursor that is obtained from the cellulose and ethanol industries, and we used carbonization and subsequent KOH activation to obtain highly porous carbon. CDI cells with a pair of lignin-derived carbon electrodes presented an initially high salt adsorption capacity but rapidly lost their beneficial desalination performance. To capitalize on the high porosity of lignin-derived carbon and to stabilize the CDI performance, we then used asymmetric electrode configurations. By using electrodes of the same material but with different thicknesses, the desalination performance was stabilized through reduction of the potential at the positive electrode. To enhance the desalination capacity further, we used cell configurations with different materials for the positive and negative electrodes. The best performance was achieved by a cell with lignin-derived carbon as a negative electrode and commercial activated carbon as a positive electrode. Thereby, a maximum desalination capacity of 18.5 mg g was obtained with charge efficiency over 80 % and excellent performance retention over 100 cycles. The improvements were related to the difference in the potential of zero charge between the electrodes. Our work shows that an asymmetric cell configuration is a powerful tool to adapt otherwise inappropriate CDI electrode materials.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Charge and Potential Balancing for Optimized Capacitive Deionization Using Lignin‐Derived, Low‐Cost Activated Carbon Electrodes

et al. 2018

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“…To effectively avoid Faradaic reactions in (M)CDI, the applied voltage in the constant voltage (CV) mode should not exceed 0.8 V [59,60]. The applied voltage ranged from 0.5 V to 0.8 V in this study.…”

Section: Parameters and Operating Conditionsmentioning

confidence: 99%

“…The flow of water was incompressible and isothermal. Neither Faradaic reaction nor electrode electronic resistance was considered under the range of applied voltage [59,60] and feed water concentration [34], respectively. The electrostatic effect of the charges of the IEM and the electrodes on diffusivity was assumed negligible [52,62,63].…”

Section: Parameters and Operating Conditionsmentioning

confidence: 99%

Exploring the Function of Ion-Exchange Membrane in Membrane Capacitive Deionization via a Fully Coupled Two-Dimensional Process Model

Zhang

Reible

2020

Processes

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In the arid west, the freshwater supply of many communities is limited, leading to increased interest in tapping brackish water resources. Although reverse osmosis is the most common technology to upgrade saline waters, there is also interest in developing and improving alternative technologies. Here we focus on membrane capacitive deionization (MCDI), which has attracted broad attention as a portable and energy-efficient desalination technology. In this study, a fully coupled two-dimensional MCDI process model capable of capturing transient ion transport and adsorption behaviors was developed to explore the function of the ion-exchange membrane (IEM) and detect MCDI influencing factors via sensitivity analysis. The IEM enhanced desalination by improving the counter-ions’ flux and increased adsorption in electrodes by encouraging retention of ions in electrode macropores. An optimized cycle time was proposed with maximal salt removal efficiency. The usage of the IEM, high applied voltage, and low flow rate were discovered to enhance this maximal salt removal efficiency. IEM properties including water uptake volume fraction, membrane thickness, and fixed charge density had a marginal impact on cycle time and salt removal efficiency within certain limits, while increasing cell length and electrode thickness and decreasing channel thickness and dispersivity significantly improved overall performance.

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“…). The porous electrode pair is charged with an applied voltage difference of 0.6 – 2.0 V, wherein oxidative degradation of the electrode and impeding electrolysis of water limits the available cell voltage in most cases to 1.2 V and in commercial applications to 1.5 V, respectively , , , .…”

Section: Removal Of Inorganic Compoundsmentioning

confidence: 99%

Current to Clean Water – Electrochemical Solutions for Groundwater, Water, and Wastewater Treatment

Simon

Stöckl

Becker

et al. 2018

Chemie Ingenieur Technik

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Electrochemical technologies for the treatment of industrial and municipal wastewaters, potable water, and groundwater, are presented, focusing on the main water constituents: inorganics, organics, micropollutants, and microorganisms. Removal of inorganic compounds by electrodialysis, electrocoagulation, and capacitive deionization as well as removal of organics and micropollutants by electrosorption, advanced oxidation processes, and anodic oxidation with boron‐doped diamond electrodes are reviewed. Electricity can be generated by degradation of organic compounds in microbial fuel cells and dehalogenation by cathodic reduction minimizes toxic substances in water. The disinfection of different types of water is also presented and it is shown that electrochemical methods offer versatile approaches to contribute to an sustainable future water management.

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Optimization of the voltage window for long-term capacitive deionization stability

Cited by 75 publications

References 55 publications

Charge and Potential Balancing for Optimized Capacitive Deionization Using Lignin‐Derived, Low‐Cost Activated Carbon Electrodes

Charge and Potential Balancing for Optimized Capacitive Deionization Using Lignin‐Derived, Low‐Cost Activated Carbon Electrodes

Exploring the Function of Ion-Exchange Membrane in Membrane Capacitive Deionization via a Fully Coupled Two-Dimensional Process Model

Current to Clean Water – Electrochemical Solutions for Groundwater, Water, and Wastewater Treatment

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