Electrochemically-mediated selective capture of heavy metal chromium and arsenic oxyanions from water

Su, Xiao; Kushima, Akihiro; Halliday, Cameron; Zhou, Jian; Li, Ju; Hatton, T. Alan

doi:10.1038/s41467-018-07159-0

Cited by 215 publications

(173 citation statements)

References 46 publications

Supporting

Mentioning

169

Contrasting

Order By: Relevance

“…Ferrocenium has previously been found to exhibit high uptake capacities, selectivities, and reversible electrosorption/desorption behavior for toxic transition metals in the form of oxyanions, namely, chromates and arsenates. [ 18a ] Applying the PVFc‐CB//CB system for electrosorption in a solution of 1 × 10 −3 m Na 2 Cr 2 O 7 and 20 × 10 −3 m NaClO 4 yielded a chromium uptake capacity of ≈31 mg g −1 PVFc‐CB, which matched very closely with previously reported separation results using a PVFc‐carbon nanotube composite under the same conditions ( Figure a). Remarkably, by changing the cathode electrode to NiHCF‐CB, the adsorption capacity almost doubled to ≈58 mg g −1 PVFc‐CB.…”

Section: Resultssupporting

confidence: 88%

“…[ 16 ] Of particular interest is the interaction affinity of the oxidized cationic form of PVFc, poly(vinylferrocenium) (PVFc + ), with anions other than those of the supporting electrolyte. The PVFc metallopolymer has recently been observed to exhibit redox‐mediated hydrogen bonding that imparts it with the ability to electrochemically separate organic carboxylate anions in both aqueous and organic solution with high separation factors of ≈100 in over 100‐fold excess competing electrolyte, [ 17 ] inorganic oxyanions from wastewater [ 18 ] and nuclear waste, [ 19 ] and even proteins. [ 20 ] As the activation of the redox‐species is mediated by an electrochemical stimulus, the process is reversible and desorption of adsorbed compounds can be accomplished via moderate electrochemical potential swings.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Asymmetric Iron‐Based Redox‐Active System for Electrochemical Separation of Ions in Aqueous Media

Tan

Hatton

2020

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

Electrochemically mediated redox-active processes are gaining momentum as a promising liquid-phase separation technology. Compared to conventional systems, they offer potential benefits, such as smaller energy footprints, nondestructive operation, reversibility, and tunability for specific analyte removal, with clear applications to societal and industrial challenges like water treatment and chemical synthesis. An asymmetric Faradaic cell heterogeneously functionalized with a metallopolymer at the anode and a hexacyanoferrate material at the cathode is presented for the first time. The redox-active species' iron centers enhance the electrosorption of heavy metal oxyanions with up to 98% removal in the ppb range, and offer tunable operating windows as low as ≈0.1 V at ≈1 A m −2 . By avoiding water splitting, the hexacyanoferrate cathode imparts additional advantages, namely a fourfold reduction in adsorption energy requirements, full suppression of solution pH increase, and the ability to capture redox-active catalytic anions such as polyoxometalates without altering their bulk oxidation state. This hybrid framework of a polymeric ferrocene anode and crystalline hexacyanoferrate cathode allows for simultaneous and synergistic uptake of anions and cations, respectively, creating a new asymmetric scheme for water-based separations, with foreseeable future extension to fields such as ion-sensing, energy storage, and electrocatalysis.

show abstract

Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

An Asymmetric Iron‐Based Redox‐Active System for Electrochemical Separation of Ions in Aqueous Media

Tan

Hatton

2020

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…All these results demonstrated the superior uptake, fast adsorption kinetics, and significant selectivity of PVF‐based arsenic removal compared to conventional carbon‐based electrosorption or other nanoparticle sorbents reported in literature 3d,5h–l. Prior studies have shown charge‐transfer interactions of As(V) anions toward metallopolymers, with current results indicating the strong counter‐ion binding with the trivalent form.…”

mentioning

confidence: 57%

“…Recent work has shown redox‐active/Faradaic materials as an attractive platform for selective water contaminant removal . Redox‐active metallopolymers have demonstrated remarkable uptake of anions with significant selectivity, both of organic anions and heavy metal oxyanions 8b,9. At the same time, asymmetric electrochemical systems have traditionally been proposed in energy‐storage applications to enhance capacitance and electrochemical properties .…”

mentioning

confidence: 99%

Asymmetric Redox‐Polymer Interfaces for Electrochemical Reactive Separations: Synergistic Capture and Conversion of Arsenic

et al. 2019

Self Cite

View full text Add to dashboard Cite

in water as anionic arsenate (As(V)) or arsenite (As(III)), with the latter being acutely toxic and difficult to remove. [3] Commonly employed techniques to remove arsenic are coagulation-flocculation or chemical adsorption, both which require significant chemical input, and extensive pretreatment steps for As(III) to As(V) conversion. [3c] Thus, novel removal technologies that integrate removal and conversion of arsenic are critical for sustainable environmental management.The development of advanced materials for water purification, selective contaminant removal, and improved energy efficiency is critical to tackling water-energy nexus challenges, including through the design of more effective membranes and field-assisted adsorbents. [4] Electrochemical methods for water treatment such as capacitive deionization (CDI) have garnered increased attention as a desalination technology, and also as a heavy metal removal platform, due to their efficiency and low environmental footprint compared to typical methods. [5] Electrosorption systems benefit from inherent modularity and scalability, which opens the door to point of source remediation systems. Electrochemical conversion of As(III) to As(V) on carbon electrode has been investigated previously for CDI-based arsenic remediation. [5l,6] However, low arsenic selectivity in the presence of competing ions has limited the total uptake capacity of carbon-based CDI, [5c,h-l] as most arsenic contaminated water sources are composed of 10 to 1000-fold excess salts. [7] Thus, the design of molecularly selective functional adsorbents is necessary to address these materials chemistry limitations.Recent work has shown redox-active/Faradaic materials as an attractive platform for selective water contaminant removal. [8] Redox-active metallopolymers have demonstrated remarkable uptake of anions with significant selectivity, both of organic anions and heavy metal oxyanions. [8b,9] At the same time, asymmetric electrochemical systems have traditionally been proposed in energy-storage applications to enhance capacitance and electrochemical properties. [10] Here, we leverage this electrochemical design for the first time to integrate both the separation and the reactions step electrochemically at functionalized electrodes. We seek to combine two redox-active polymer Advanced redox-polymer materials offer a powerful platform for integrating electroseparations and electrocatalysis, especially for water purification and environmental remediation applications. The selective capture and remediation of trivalent arsenic (As(III)) is a central challenge for water purification due to its high toxicity and difficulty to remove at ultra-dilute concentrations. Current methods present low ion selectivity, and require multistep processes to transform arsenic to the less harmful As(V) state. The tandem selective capture and conversion of As(III) to As(V) is achieved using an asymmetric design of two redox-active polymers, poly(vinyl)ferrocene (PVF) and poly-TEMPO-methacrylate (PTMA). D...

show abstract

“…However, polymers with this mechanism still have some limitations to be overcome, such as the poor intrinsic electronic conductivity within nonconductive polymer backbones, and deficient redox active moieties along with comparatively low ion capture capacity. With the deepening of research on polymers, some reports of high desalination performance have also appeared, [118,141,142] creating new opportunities for the development of polymer-based electrochemical cells with high desalination performance.…”

Section: Ion Capture Mechanismsmentioning

confidence: 99%

Faradaic Electrodes Open a New Era for Capacitive Deionization

et al. 2020

View full text Add to dashboard Cite

Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co-ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy-efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode-based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research.

show abstract

Electrochemically-mediated selective capture of heavy metal chromium and arsenic oxyanions from water

Cited by 215 publications

References 46 publications

An Asymmetric Iron‐Based Redox‐Active System for Electrochemical Separation of Ions in Aqueous Media

An Asymmetric Iron‐Based Redox‐Active System for Electrochemical Separation of Ions in Aqueous Media

Asymmetric Redox‐Polymer Interfaces for Electrochemical Reactive Separations: Synergistic Capture and Conversion of Arsenic

Faradaic Electrodes Open a New Era for Capacitive Deionization

Contact Info

Product

Resources

About