Capacitive desalination with flow-through electrodes

Suss, Matthew E.; Baumann, Theodore F.; Bourcier, William L.; Spadaccini, Christopher M.; Rose, Klint A.; Santiago, Juan G.; Stadermann, Michael

doi:10.1039/c2ee21498a

Cited by 361 publications

(281 citation statements)

References 31 publications

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“…However, because once the ions enter the electrodes they remain trapped electrodes, regeneration is necessary, 3,16,53 and the process is not continuous, unless complex operations are designed (e.g., desalination with wires). 54 As opposed to existing technologies, the composite cell we propose promises the possibility of continuous operation, because there is no need of electrodes regeneration (Fig.…”

Section: Resultsmentioning

confidence: 99%

Promising Performance Indicators for Water Desalination and Aqueous Capacitors Obtained by Engineering the Electric Double Layer in Nano-Structured Carbon Electrodes

Striolo

2015

J. Phys. Chem. C

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It is well known that the electric double layer plays important roles in a variety of applications, ranging from biology to materials sciences. Many studied the electric double layer using a variety of techniques, and as a result our understanding is mature, although not complete. Based on detailed understanding, we expect that by manipulating the electric double layer we could advance tremendously applications in the water-energy nexus. This is particularly true for electric double layer capacitors and capacitive desalination devices. However, such manipulation is not straightforward because of a competition of phenomena that occur within the electric double layer itself, including solvation effects, excluded volume phenomena, and ion-ion correlations. Using molecular dynamics simulations, we designed a composite graphene-based electrode to manipulate structural and dynamical properties of the electric double layer. Our design favors the formation of the compact Helmholtz layer. Inherent to our design is that the compact Helmholtz layer not only is atomically thick, but it is also highly mobile in the direction parallel to the charged surface. We suggest here how to exploit the properties of the engineered electric double layer towards developing a new continuous desalination process that combines the advantages of membrane and capacitive desalination processes, reducing their shortcomings.Insights on the molecular mechanisms relevant to the water-energy nexus are provided.2

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Section: Resultsmentioning

confidence: 99%

Promising Performance Indicators for Water Desalination and Aqueous Capacitors Obtained by Engineering the Electric Double Layer in Nano-Structured Carbon Electrodes

Striolo

2015

J. Phys. Chem. C

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“…Because the amount of ions that can be captured using CD scales with the electrode's surface area, conductive porous materials such as active carbons with high surface area are used (115,116). Challenges to bring CD to fruition include the maximization of the capacitance, to capture more ions, and synchronization of water flow through the device (117). In fact, once ions are adsorbed on the electrodes, the latter need to be regenerated (118), making CD processes discontinuous, unless complicated operations are designed (e.g., desalination with wires (119)).…”

Section: Alternative Water Desalination Processes: Capacitive Deionizmentioning

confidence: 99%

The Carbon-Water Interface: Modeling Challenges and Opportunities for the Water-Energy Nexus

Striolo

Michaelides

Joly

2016

Annu. Rev. Chem. Biomol. Eng.

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Providing clean water and sufficient affordable energy to all without compromising the environment are key priorities of the scientific community. Many recent studies have focused on carbon--based devices in the hope of addressing these grand challenges, justifying and motivating detailed studies of water in contact with carbonaceous materials. Such studies are becoming increasingly important because of the miniaturization of newly proposed devices, with ubiquitous nano--pores, large surface--to--volume ratio, and many, perhaps most of the water molecules at contact with a carbon--based surface. In this brief review we discuss some recent advances obtained by simulations and experiments in the development of carbon--based materials for applications in water desalination. We suggest possible ways forward, with particular emphasis on the synergistic combination of experiments and simulations, with simulations now sometimes offering sufficient accuracy to provide fundamental insights. We also point the interested reader to recent works that complement our short summary on the state of the art of this important and fascinating field. 2 Introduction: the importance of reverse osmosis in water desalinationThe scientific community is facing the challenge of providing technological solutions for the water--energy nexus while preserving the environment. Carbon--based devices have been developed both for desalinating water and for storing energy. Such devices are characterized by vast carbon--water interfaces, due to the ubiquity of nano--pores. It is indeed possible that many, perhaps most water molecules within such devices come in contact with the carbon surface. Hence, a detailed understanding of water--carbon interfaces is necessary to ensure progress. Here, we review some recent advances obtained by atomistic simulations and experiments on this field. Traditional water desalination approaches such as multi--flash distillations are widely used, but require large amounts of energy. As such, they are not sustainable in the long run. Reverse osmosis (RO) has become the technology of choice for most new installations. Two innovations are considered to be responsible for the wide application of RO. The first was the introduction of thin film composite membranes; the other was the implementation of energy recovery devices that re--use part of the energy present in pressurized brine (i.e., pressure exchangers and efficient pumps) (1, 2). Although RO is mature and reliable, it remains energy intensive (3--5). At its core are membranes permeable to water and impermeable to salt. The state--of--the art membranes, based on polyamide thin film composites, degrade in the presence of chlorine (which makes disinfection difficult) and are prone to fouling (6). Many believe that 'in order for desalination to live up to the water challenges of the 21 st century a step--change is needed in RO membrane technology' (7). Although high mechanical strength as well as resistance to degradation and fouling are prerequisites to practical appli...

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“…13 In such cases, the detoxification of aqueous Cr(VI), particularly when Cr(VI) is present at low concentration, often shows low current efficiency and results in high energy demand. 17 Flow-through porous electrodes demonstrate high current efficiency, enhanced mass transfer, and high volumetric rates of reaction and have been used in fuel cells, 18 electrooxidation, 19 desalination, 20 and adsorption. 21 This flow-through architecture enables optimal utilization of the active sites inside the porous electrodes and provides enhanced rates of mass transport, which could be especially useful for treatment of dilute solutions.…”

Section: ■ Introductionmentioning

confidence: 99%

Microfluidic Flow through Polyaniline Supported by Lamellar-Structured Graphene for Mass-Transfer-Enhanced Electrocatalytic Reduction of Hexavalent Chromium

Zhang

et al. 2015

Environ. Sci. Technol.

104

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Owing to its high efficiency and environmental compatibility, electroreduction holds great promise for the detoxification of aqueous Cr(VI). However, the typical electroreduction system often shows poor mass transfer, which results in slow reduction kinetics and hence higher energy consumption. Here, we demonstrate a flow-through electrode of polyaniline supported on lamellar-structured graphene (LGS−PANI) for electrocatalytic reduction of Cr(VI). The reaction kinetics of the LGS− PANI flow-through electrodes are 6.4 times (at acidic condition) and 17.3 times (at neutral condition) faster than traditional immersed parallel-plate electrodes. Computational fluid dynamics simulation suggests that the flowthrough mode greatly enhances the mass transfer and that the nanoscale convection induced by the PANI nanodots increases the nanoscale mass transport in the interfacial region of the electrode/ solution. In situ Raman spectroscopy shows that the PANI−Cr(VI) redox reactions are dominated by the leucoemeraldine/ emeraldine transition at 1.5 V cell voltage, which also remarkably contributes to the fast reaction kinetics. Using single-pass flowthrough mode, the LGS−PANI electrode reaches an average reduction efficiency of 99.

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Capacitive desalination with flow-through electrodes

Cited by 361 publications

References 31 publications

Promising Performance Indicators for Water Desalination and Aqueous Capacitors Obtained by Engineering the Electric Double Layer in Nano-Structured Carbon Electrodes

Promising Performance Indicators for Water Desalination and Aqueous Capacitors Obtained by Engineering the Electric Double Layer in Nano-Structured Carbon Electrodes

The Carbon-Water Interface: Modeling Challenges and Opportunities for the Water-Energy Nexus

Microfluidic Flow through Polyaniline Supported by Lamellar-Structured Graphene for Mass-Transfer-Enhanced Electrocatalytic Reduction of Hexavalent Chromium

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