Emerging investigator series: electrochemically-mediated remediation of GenX using redox-copolymers

Medina, Paola Baldaguez; Cotty, Stephen; Kim, Kwiyong; Elbert, Johannes; Su, Xiao

doi:10.1039/d1ew00544h

Cited by 10 publications

(11 citation statements)

References 44 publications

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“…Electrosorption based on redox-active materials has proven to be effective for ion-selective separations by combining molecularly-controllable affinity, modularity, scalability, and no need for chemical reagents for regeneraton 22 – 27 . While these materials have been recently used for various contaminant remediation strategies 22 – 24 , 28 , we explore for the first time the applicability of these redox processes for the electrified capture and downstream conversion of nitrogen species. To impart electrocatalytic properties into our electrode, we selected cobalt oxide (Co 3 O 4 ) as a model nitrate-reducing electrocatalyst based on its activity and durability under various pH-potential conditions 29 – 32 .…”

Section: Introductionmentioning

confidence: 99%

Coupling nitrate capture with ammonia production through bifunctional redox-electrodes

Kim

Zagalskaya

et al. 2023

Nat Commun

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Nitrate is a ubiquitous aqueous pollutant from agricultural and industrial activities. At the same time, conversion of nitrate to ammonia provides an attractive solution for the coupled environmental and energy challenge underlying the nitrogen cycle, by valorizing a pollutant to a carbon-free energy carrier and essential chemical feedstock. Mass transport limitations are a key obstacle to the efficient conversion of nitrate to ammonia from water streams, due to the dilute concentration of nitrate. Here, we develop bifunctional electrodes that couple a nitrate-selective redox-electrosorbent (polyaniline) with an electrocatalyst (cobalt oxide) for nitrate to ammonium conversion. We demonstrate the synergistic reactive separation of nitrate through solely electrochemical control. Electrochemically-reversible nitrate uptake greater than 70 mg/g can be achieved, with electronic structure calculations and spectroscopic measurements providing insight into the underlying role of hydrogen bonding for nitrate selectivity. Using agricultural tile drainage water containing dilute nitrate (0.27 mM), we demonstrate that the bifunctional electrode can achieve a 8-fold up-concentration of nitrate, a 24-fold enhancement of ammonium production rate (108.1 ug h−1 cm−2), and a >10-fold enhancement in energy efficiency when compared to direct electrocatalysis in the dilute stream. Our study provides a generalized strategy for a fully electrified reaction-separation pathway for modular nitrate remediation and ammonia production.

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Section: Introductionmentioning

confidence: 99%

Coupling nitrate capture with ammonia production through bifunctional redox-electrodes

Kim

Zagalskaya

et al. 2023

Nat Commun

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“…Integration of this system with electrocatalytic degradation methods, such as boron-doped diamond electrodes or plasma processes, can serve as a platform to efficiently degrade short-chain PFAS. 31,36,50…”

Section: Evaluation Of Fluorinatedmentioning

confidence: 99%

“…Electrochemical control has been shown to be an efficient method to remove legacy long-chain PFAS from water. , For example, PFOA was successfully captured and released by electrochemical tuning of the cationic group in redox-active copolymers . Moreover, electrochemical methods have shown great promise for water remediation due to their high selectivity and modular configurations that can be implemented with renewable energy sources while eliminating the need for chemicals or spent solvents to regenerate the adsorbent. − While many studies report the influence of electrostatic interactions for binding PFAS, there is a lack of understanding of the extent of effects of electroactivity in PFAS sorption and even more so for the emerging short-chain PFAS. Furthermore, previous electrochemical studies did not consider the effect of controlling fluorophilic interactions, which could be key to removing short-chain PFAS.…”

Section: Introductionmentioning

confidence: 99%

Imparting Selective Fluorophilic Interactions in Redox Copolymers for the Electrochemically Mediated Capture of Short-Chain Perfluoroalkyl Substances

et al. 2023

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With increasing regulations on per- and polyfluoroalkyl substances (PFAS) across the world, understanding the molecular level interactions that drive their binding by functional adsorbent materials is key to effective PFAS removal from water streams. With the phaseout of legacy long-chain PFAS, the emergence of short-chain PFAS has posed a significant challenge for material design due to their higher mobility and hydrophilicity and inefficient removal by conventional treatment methods. Here, we demonstrate how cooperative molecular interactions are essential to target short-chain PFAS (from C4 to C7) by tailoring structural units to enhance affinity while modulating the electrochemical control of capture and release of PFAS. We report a new class of fluorinated redox-active amine-functionalized copolymers to leverage both fluorophilic and electrostatic interactions for short-chain PFAS binding. We combine molecular dynamics (MD) simulations and electrosorption to elucidate the role of the designer functional groups in enabling affinity toward short-chain PFAS. Preferential interaction coefficients from MD simulations correlated closely with experimental trends: fluorination enhanced the overall PFAS uptake and promoted the capture of less hydrophobic short-chain PFAS (C ≤ 5), while electrostatic interactions provided by secondary amine groups were sufficient to capture PFAS with higher hydrophobicity (C ≥ 6). The addition of an induced electric field showed favorable kinetic enhancement for the shortest PFAS and increased the reversibility of release from the electrode. Integration of these copolymers with electrochemical separations showed potential for removing these contaminants at environmentally relevant conditions while eliminating the need for chemical regeneration.

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“…23,33−36 Additionally, redoxmediated electrosorption can offer rapid kinetics for target capture and remarkable efficiency for ion recovery. 35,37 Recently, polyvinyl ferrocene (PVF) was demonstrated as a viable selective separations platform for homogeneous catalyst recovery with industrially pertinent hydrosilylation, cross- coupling, and Wacker oxidation reactions, 38 through selective interactions with anionic platinum complexes.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Electrochemical separations offer a promising avenue for ion-selective separations from dilute solutions, with capture and release modulated solely by electrochemical potential. − Electrification is a growing movement in the industry due to the advantages of accessing a unified energy source for process units and the possibility of integration with an renewable energy infrastructure and workflow. ,− Further, recent developments with redox-active materials offer a novel electrochemical separations platform, demonstrating a high degree of tunable target selectivity through molecular design and modulation of operational parameters compared to other electrochemical separation methods such as capacitive deionization and electrodeposition. ,− Additionally, redox-mediated electrosorption can offer rapid kinetics for target capture and remarkable efficiency for ion recovery. , Recently, polyvinyl ferrocene (PVF) was demonstrated as a viable selective separations platform for homogeneous catalyst recovery with industrially pertinent hydrosilylation, cross-coupling, and Wacker oxidation reactions, through selective interactions with anionic platinum complexes.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically Mediated Recovery and Purification of Gold for Sustainable Mining and Electronic Waste Recycling

Cotty

Kim

2023

ACS Sustainable Chem. Eng.

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Rapid growth of the industrial and electronics sectors has led to an ever-mounting demand for gold. Gold mining can be highly resource-intensive, due to the need for selective gold separations from dilute streams, in the presence of multicomponent metallic species. The development of efficient gold separation technologies is critical to mitigate the declining gold purity in mined ores and to meet the need for electronic waste recycling. We propose a modular electrochemical separation platform via metallopolymer-functionalized electrodes to selectively recover and concentrate gold from electronic waste and simulated mining streams. Polyvinylferrocene (PVF) redox-electrodes captured cyano-gold with 10-fold higher uptake (>200 mg/g) than conventional activated carbon and, importantly, demonstrated an exceptional separation factor >20 for gold vs competing metals in mining and electronic waste, including silver, copper, nickel, and iron. Rapid gold uptake was observed within 5 min, and electrochemically mediated release and concentration achieved a remarkable up-concentration ratio of 20:1. Electrochemical recycling of gold from real-world electronic waste (e.g., RAM boards) highlighted our system as a drop-in replacement for activated carbon sorbent, with a recovery efficiency 99% and superior technoeconomics, leading to a 94% cost reduction and over 90% final gold purity. Redox-mediated electrochemical separations can be a promising avenue for the energy-efficient, sustainable, and process-intensified gold recovery and recycling.

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Emerging investigator series: electrochemically-mediated remediation of GenX using redox-copolymers

Abstract: Per- and polyfluorinated alkyl substances (PFAS) are persistent contaminants that have been continuously detected in groundwater and drinking water around the globe. Hexafluoropropylene oxide dimer acid (tradename GenX) has been...

Cited by 10 publications

References 44 publications

Coupling nitrate capture with ammonia production through bifunctional redox-electrodes

Coupling nitrate capture with ammonia production through bifunctional redox-electrodes

Imparting Selective Fluorophilic Interactions in Redox Copolymers for the Electrochemically Mediated Capture of Short-Chain Perfluoroalkyl Substances

Electrochemically Mediated Recovery and Purification of Gold for Sustainable Mining and Electronic Waste Recycling

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