Solar desalination coupled with water remediation and molecular hydrogen production: a novel solar water-energy nexus

Kim, Seong Hun; Piao, Guangxia; Han, Dong Suk; Shon, Ho Kyong; Park, Hyunwoong

doi:10.1039/c7ee02640d

Cited by 122 publications

(85 citation statements)

References 37 publications

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“…Tandem Faradaic systems have been successfully used previously as a medium to minimize side‐reactions and increase current efficiency 8c,11. In this study, an asymmetric redox‐active design is proposed, in which a working electrode is functionalized with a poly(vinyl)ferrocene (PVF), and the counter‐electrode with poly‐TEMPO‐methacrylate (PTMA), a polymer containing redox‐active nitroxide radical moieties (see Figure a).…”

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confidence: 99%

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

et al. 2019

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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...

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confidence: 99%

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

et al. 2019

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“…showed an excellent example of solar-based desalination. [78] As ar esult, the production of NaOH could become more economically viable on ac ost per energy-unit basis.O nsite production of NaOH would also reduce the energy demand and hazards involved in chemical transportation. To summarize,t he system produces chemicals such as NaOH and HCl and provides ap ossibility of fluidity and interconnectedness among the water, renewable energy,and chemical industries.…”

Section: Methodsmentioning

confidence: 99%

“…[74] Some recent studies also suggest that renewable energy sources have the potential to provide more sustainable and economical energy to drive membrane-based desalination processes, [75][76][77] especially in consideration of new developments in the renewable energy sector. [78] As ar esult, the production of NaOH could become more economically viable on ac ost per energy-unit basis.O nsite production of NaOH would also reduce the energy demand and hazards involved in chemical transportation. [78] As ar esult, the production of NaOH could become more economically viable on ac ost per energy-unit basis.O nsite production of NaOH would also reduce the energy demand and hazards involved in chemical transportation.…”

Section: Feasibility and Product Usagementioning

confidence: 99%

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

et al. 2019

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The rising use of seawater desalination for fresh water production is driving a parallel rise in the discharge of high‐salinity brine into the ocean. Better utilization of this brine would have a positive impact on the energy use, cost, and environmental footprint of desalination. Furthermore, intermittent renewable energy can easily power the brine utilization and, for reverse osmosis technology, the entire desalination plant. One pathway toward these goals is to convert the otherwise discharged brine into useful chemicals; waste could be transformed into sodium hydroxide or caustic soda (NaOH) and hydrochloric acid (HCl). In this Minireview, we discuss opportunities and challenges for integrated valorization of desalination brine through NaOH and HCl recovery.

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“…Details of the analytical method for urea are available elsewhere. 14 The concentrations of free chlorine and total chlorine (i.e., free chlorine plus combined chlorine) were determined with N,N-diethyl-p-phenylenediamine (DPD) reagent (Hach methods 10101 and 10102). The total organic carbon (TOC) of the anolyte was estimated using a TOC analyzer (TOC-L, Shimadzu).…”

Section: Electrocatalysis and Chemical Analysismentioning

confidence: 99%

“…[12][13] Despite this uniqueness, the effects of RCSs become relevant when the chloride concentration is sufficiently high (typically, >5 mM). [14][15][16][17] Brackish water and seawater can be considered as vast chloride supplies (salinities of 1-10 g L −1 and 36 g L −1 , respectively) and can therefore be used for RCSmediated electrocatalysis.…”

Section: Introductionmentioning

confidence: 99%

High-Efficiency Solar Desalination Accompanying Electrocatalytic Conversions of Desalted Chloride and Captured Carbon Dioxide

Kim

Piao

Kim

et al. 2019

ACS Sustainable Chem. Eng.

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The sustainability of conventional water-and energy-associated systems is being examined in terms of water-energy nexus. This study presents a high-efficiency, off-grid solar desalination system for saline water (salinity 10 and g L −1) that accompanies electrocatalytic oxidations of chloride and, consequently, urine via oxidized chlorine species, while concomitantly producing formate from captured CO2. A variable number of desalination cell arrays is placed between a double-layered nanoparticulate titania electrocatalyst (Ti/IrxTa1−xOy/nano-TiO2; denoted as n-TEC) anode and a porous dendrite Bi cathode. A potential bias to the n-TEC and Bi pair initiates the transport of chloride and sodium ions in the saline water to the anode and cathode cells, respectively, at an ion transport efficiency of ~100% and a specific energy consumption of ~1.9 kWh m −3. During the desalination, the n-TEC anode catalyzes the conversion of the transported chloride into reactive chlorine species, which in turn mediate the decomposition of urine in the anode cell. Concurrent with the anodic process, formate is continuously produced at a Faradaic efficiency of >95% from the CO2 captured in the catholyte. When a photovoltaic cell (power conversion efficiency of ~18%) is coupled to the stack device with five desalination cells, the three independent processes synergistically proceed at a maximum overall solar-to-desalination system efficiency ~16% and a maximum solar-toformate chemical energy conversion efficiency of ~7%.

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Solar desalination coupled with water remediation and molecular hydrogen production: a novel solar water-energy nexus

Abstract: A novel solar water-energy nexus technology is presented that combines the solar desalination of saline water and desalination-driven wastewater remediation coupled with the production of H2.

Cited by 122 publications

References 37 publications

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

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

Integrated Valorization of Desalination Brine through NaOH Recovery: Opportunities and Challenges

High-Efficiency Solar Desalination Accompanying Electrocatalytic Conversions of Desalted Chloride and Captured Carbon Dioxide

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