Electrosorption Capacity Research Articles

High-performance fluoride removal by Fe/N co-doped microporous carbon: Mechanism of capacitive deionization with FeNx sites

Fluoride pollution is becoming increasingly serious with industrial growth. Controlling fluoride pollution have become important environmental issues of global concern. Transition metal nitrides are excellent CDI electrode materials due to their excellent conductivity and electrochemical stability. In this study, FeNx/C was synthesized as an electrode material for using the capacitive deionization (CDI) technique to achieve the effective removal of fluoride ions from wastewater. Its high specific surface area (463.278 mg/g) and high capacitance (44.29 F/g) were demonstrated and it had a high adsorption capacity of 158.33 mg/g. FeN3 and FeN4 were used as the main sites as capacitive deionization for removing fluoride from the water by chemisorption and hydrogen bonding. The higher adsorption energy by density functional calculation also indicated that the existence of Fe-N coordination bond effectively improved its electrosorption capacity. This study is beneficial to provide references and research ideas for removing fluoride in the CDI field.

Flexible beads-on-string hierarchically porous carbon nanofiber/nanotube composites for enhanced capacitive deionization performance in water desalination

Capacitive deionization (CDI) has garnered significant interest for desalinating water and wastewater. However, electrode materials have remained a primary constraint in CDI technology. This study incorporated carbon nanotubes (CNTs) into a polyacrylonitrile (PAN) solution to synthesize a hierarchically porous activated carbon nanofiber (ACNF)/CNT composite. The ACNF/CNT composite possesses a highly flexible structure characterized by a distinctive beads-on-string morphology. It exhibits a specific surface area of 699 m2/g, a specific pore volume of 0.448 cm3/g, and an average pore width of 3.38 nm. The composite is composed of micropores (38 %), mesopores (59 %), and macropores, creating a multi-scale porous architecture. The surface capacitance of the ACNF/CNT composite is six times greater than that of the ACNF alone, and its charge transfer resistance is reduced to one-tenth. Furthermore, the electrosorption capacity of the ACNF/CNT composite as CDI electrodes was found to be 17.3 mg/g for a 500 mg/L NaCl solution, demonstrating stability over 30 cycles. Kinetic studies suggest that the mesopore-rich beads-on-string structure enhances intraparticle diffusion and the electrosorption process. The ACNF/CNT composite also demonstrates exceptional flexibility and mechanical stability, which are crucial for its application at a pilot scale. This study introduces a novel hierarchically porous electrode material for CDI desalination.

Cobalt sulfide derived from metal organic framework for selective treatment of low concentration copper wastewater: Catalytic ability, reaction efficacy, and mechanism

Here, cobalt sulfide derived from metal organic frameworks (S-Co/MOF) was synthesized and applied in capacitive deionization (CDI) for the selective removal of Cu2+. A series of characterizations confirmed the successful preparation of S-Co/MOF. Under an applied voltage of 1 V and an initial concentration of 25 mg L−1, the electro-sorption capacity of the S-Co/MOF electrode can reach 57.39 mg g−1, which is much higher than that of the Co/MOF electrode. Moreover, the S-Co/MOF electrode exhibits excellent cycling stability under continuous operations. The S-Co/MOF shows effective selectivity for Cu2+ when removing copper-plating wastewater with coexisting ions such as Pb2+, Mn2+, Zn2+, and Cd2+. Density functional theory calculations also confirm that the Co/MOF with high binding energy is beneficial to the electro-sorption process. Consequently, the CDI with the S-Co/MOF electrode provides an effective method for the selective removal of copper-plating wastewater, paving the way for innovative electrochemical systems in water treatment applications.

Selective electrosorption of silver ions from wastewater by biomass-derived N, S co-doped hierarchical porous carbon

The recovery of precious silver (Ag) from wastewater, a dual pursuit of environmental sustainability and economic benefits, faces a formidable challenge in the selective extraction of Ag+ ions amidst a matrix of other metal ions. To address this, we developed a novel N, S co-doped hierarchical porous carbon (NSPC) derived from a renewable precursor of Camellia oleifera shell. As the electrode material for capacitive deionization (CDI), the NSPC exhibited a high electrosorption capacity of 480.5 mg g−1 for Ag+ ions under an operating voltage of 1.2 V. Owing to the strong reaction between Ag+ and S functional groups and the synergistic effect from a hierarchical porous structure and N doping, the formation of Ag2S and elemental Ag is facilitated, and the NSPC cathode could selectively remove nearly 100 % of Ag+ ions from saline water and a solution containing Ni2+, Co2+, Pb2+, Zn2+, and Fe3+ ions. Furthermore, the NSPC cathode showed a high anti-interference ability in the presence of anions (C10H14N2O82−, C4H4O62−, C5H7O5COO− and HCO3−) and excellent reusability until 9 cycles. The impressive results show that the biomass-derived NSPC has the potential for rapid and selective recovery of silver from wastewater and offers a solution for environmental remediation and metal resource recovery.

Employing Manganese Dioxide and Bamboo Carbon for Capacitive Water Desalination and Disinfection.

A manganese dioxide (MnO2)/bamboo carbon (BC) composite was prepared using hydrothermal and impregnation methods and used for the capacitive desalination (CDI) and disinfection of water. The results showed that these composites had fast Na+ ion exchange and charge transfer properties. During the CDI process, these composites' electrodes exhibited good cycle stability and electrosorption capacity (4.09 mg/g) and an excellent bactericidal effect. These carbon-based composite electrodes' bactericidal rate for Escherichia coli could reach 99.99% within 180 min; therefore, they had good performance and are a good choice for high-performance deionization applications.

Interface engineering of laminated redox-copolymers for electrochemical remediation of perfluoroalkyl substances

Redox polymers now show promise for selective removal of perfluoroalkyl substances from a complex aqueous matrix at high energy efficiency and no secondary pollution. However, self-agglomeration of redox polymers is a dominating barrier to constructing a low-cost, stable system in practical applications. Herein, we introduce polymer interface engineering strategy to enhance the activity of amine functionalities and nitrous oxide radicals in copolymers composed of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl and 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine. The grafted laminated redox polymer on multi-walled carbon nanotubes (termed MWCNT-g-P(TMPMA-co-TMA)) via free-radical polymerization demonstrated a 19.1–59.9 % increase in the electrosorption capacity with a maximum value (Qm) of 725.09 mg g−1 and a pseudo-first-order rate constant k1 = 1.46 min−1 and sustainable regeneration efficiency at ∼80 %. The core–shell structure of MWCNT-g-P(TMPMA-co-TMA) with a laminated redox polymer layer of ∼5 nm processed a low charge transfer resistance, which is expected to contribute to the enhanced capture performance and stability. An integrated system consisting of a MWCNT-g-P(TMPMA-co-TMA) electrode and a boron-doped diamond electrode can efficiently separate and degrade trace-concentration PFOA from industrial wastewater at high mineralization efficiency. This work provides insight into the design and optimization of redox active materials for water purification and beyond.

Nitrate and phosphate removal by capacitive deionization using nanocellulose/polypyrrole electrodes

Capacitive deionization (CDI) is a desalination technology that shows promise for removing nitrate and phosphate ions. The main components of CDI cells are electrodes, which are typically made from activated carbon (AC). However, the electrosorption performance of AC electrodes is limited because of the negative zeta potential, hydrophobicity, and oxidation resulting in co–ions’ repulsion. This study investigates binder-free polypyrrole-coated nanocellulose (NC/PPy) electrodes, which are hydrophilic and possess various functional groups, as an alternative to AC electrodes. An asymmetric CDI cell with an NC/PPy positive electrode demonstrated greater energy and charge efficiencies compared to a symmetric cell. The NC/PPy electrode exhibited a threefold electrosorption capacity towards nitrate ions compared to the AC electrode, and 4.5 times higher than for phosphate ions. The electrosorption mechanism revealed by first-principles modeling indicates similar sorption energies for nitrate and phosphate ions, with higher nitrate capacity due to co-ion repulsion and diffusion effects.

Selective electro-capacitive deionization of Yb(III) by nanospherical N-doped carbon supported nickel‑iron bimetallic oxide, nitride and phosphide

The separation of rare earth elements from the mining waste water is highly important but still facing challenge. In this study, three different porous composite electrode materials were well-designed by decorating the nickel‑iron bimetallic oxide, nitride or phosphide onto nitrogen-doped carbon nanosphere, respectively (termed as NiFeO@NC, NiFeN@NC and NiFeP@NC), and utilized in capacitive deionization device for electrosorption of Yb(III) from water under the low-voltage electric field. The characterization and electrochemical results indicated that the incorporation of N or P atom lead to the reduced specific surface area and the enhanced electrochemical properties (i.e., larger specific capacitance, lower charge transfer resistance). In addition, NiFeN@NC and NiFeP@NC exhibited the excellent electrosorption capacities of Yb(III) with 105.24 mg·g−1 and 90.31 mg·g−1, respectively, under conditions of a flow rate of 20 mL·min−1, a voltage of 1.2 V, and pH of 5.0, which was extremely higher than NiFeO@NC (i.e., 50.7 mg·g−1). Moreover, all these three materials also demonstrated the remarkable electrosorption selectivity of Yb(III) from the mixed solution, and the robust durability with over 90 % of initial capacities after ten consecutive electrosorption-desorption cycles. Furthermore, the XPS characterizations and electrosorption results revealed that the electrosorption mechanism mainly depended on the synergistic effects of intrinsic Faraday redox reaction, electric double layer capacitance and active binding sites. Therefore, this work provided a feasible strategy for the separation of rare earth elements from aqueous solution, and the prospective applications related to the recovery of rare earth elements from mining wastes or spent permanent magnets in future life.

The Faradaic-Induced hybrid capacitive engine enables high-performance selective defluorination via capacitive deionization

Fluoride (F-) contamination has become a pressing environmental concern owing to its extensive origins and severe toxicity. Capacitive deionization (CDI) emerges as a promising technique for efficient defluorination, with the development of electrode materials being pivotal to its efficiency. Herein, we present a novel design of Sb-decorated N-rich carbon composites (SNTPCs) for the formation of a hybrid capacitive engine that integrates Faradaic-induced pseudocapacitance and electrical double layer capacitance, enabling efficient F- electrosorption. This approach features a distinctive N-rich carbonaceous laminar framework that not only guarantees rapid ion diffusion and electron transfer but also provides a dense electrical double layer for F- storage. The Sb sites are electrically stimulated to release the intrinsic affinity with F-, forming the Faradaic Sb-F bonds. The SNTPC2 electrode exhibits the exceptional saturation removal capability and dynamic electrosorption capacity for defluorination, reaching 178.58 and 34.77 mg F/g at 1.2 V respectively, which exceeds most reported F- capture electrodes. It also demonstrates excellent selectivity towards F- in complex conditions and exhibits effectiveness across a wide range of pH values. Additionally, the utilized electrode performs outstanding regeneration performance after 20 consecutive cycles. This study provides innovative perspectives for the effective elimination of fluoride pollution in aquatic environments.

Upcycling waste polyethylene terephthalate (PET) bottles into high-performance activated carbon for electrochemical desalination

Upcycling waste polyethylene terephthalate (PET) bottles has attracted intensive research interests. This simultaneously alleviates plastic pollution and achieves a waste-to-resource strategy. Waste PET water bottles were used to fabricate value-added activated carbon (AC) electrodes for capacitive deionization (CDI). The KOH activation temperature (greater than 700 °C) prominently affected the physi-chemical properties and desalination performance of PET-derived activated carbons (PET-AC). Profiting from a large Brunauer–Emmet–Teller specific surface area (1448 m2 g−1) with a good mesoporous structure (the ratio of the mesopore volume to the total pore volume was 41.3%), PET-AC-1000 (activated at 1000 °C) possessed a huge specific capacitance of 108 F g−1 for capacitive ion storage. Moreover, when utilized as the electrode material in single-pass CDI, PET-AC-1000 exhibited a maximum electrosorption capacity of 10.82 ± 0.11 mg g−1 and a low level of energy consumption (0.07 kWh mol−1), associated with good electrochemical charging-discharging cyclic stability. The results provide a promising facile approach to tackle the challenge of plastic pollution and promote the advancement of electrode materials for economic affordable and energy-efficient electrochemical desalination process, which meets the United Nations (UN) sustainable development goals (SDGs).

How Does Temperature Affect the Charge Transfer Process in Flow Electrode Capacitive Deionization?

In this study, we investigate how temperature variations, a key environmental factor, affect the charge transfer process in FCDI systems across seasonal variation and geographical distributions, which is crucial for optimizing FCDI performance but has not received adequate attention. Therefore, thermal-assisted FCDI systems were proposed by controlling the temperatures of the flow electrode and saline water to simulate the environmental conditions, and the temperature effects on the charge transport and desalting ability of FCDI were investigated. First, the isothermal mode was performed, where the flow electrode and saline water were controlled at the same temperatures (0-50 °C) to simulate the natural atmospheric temperature fluctuations and industrial circulating cooling water system. Experimental results showed a strong positive correlation between temperature and electrosorption dynamics. Elevated temperatures significantly improved ion electromigration and diffusion, thereby enhancing the electrosorption capacity of the FCDI device. On this basis, the nonisothermal mode was designed via maintaining the temperature of the flow electrode at 50 °C to improve the desalination performance of FCDI for saline water at different temperatures (0-50 °C). Finally, the East China seawater and industrial circulating cooling water were both desalted successfully to confirm the feasibility of the temperature field in the practical application of FCDI.

Enhancement of Co(II) removal via coupling of electrosorption and electrodeposition using asymmetric electrode from wastewater

The growing demand for nuclear energy and the promotion of nuclear technology applications will generate large quantities of cobalt-containing wastewater. The efficient removal of cobalt from radioactive wastewater is of great significance for the resource regeneration and environmental protection. However, conventional removal methods are constrained by the poor removal efficiency and slow removal kinetics. Herein, the sulfonated polyether ether ketone coated activated carbon fibers (anode)/activated carbon fibers (cathode) asymmetric electrodes was proposed to boost the Co(II) electrosorption performance. The experimental results showed that compared to traditional symmetric electrodes, the theoretical maximum electrosorption capacity (116.19 mg·g−1) had an exceptional enhancement of 69 %. The voltage and initial pH of the solution had an undeniable impact on the efficiency of cobalt electrosorption. Furthermore, more than 75 % of Co(II) was rapidly immobilized within 3 h. The kinetic fitting indicated that the electrosorption process was more appropriately described by pseudo-second-order kinetic model. The Co(II) removal efficiency was up to 80 % under the conditions of coexistence with Na+, Mn2+, Ni2+, Zn2+, Sr2+, and Cs+. More importantly, it combines two synthetic mechanisms of electrosorption and electrodeposition to realize the purification of cobalt-containing wastewater. Overall, considering the fast and highly-efficient cobalt removal performance and innate economy, the asymmetric electrosorption for cobalt removal provides new insights into the treatment of cobalt-containing wastewater.

Selective mono/divalent ion separation in bifunctional ionomeric capacitive deionization incorporated with counter-charge ionomer layer

In this study, a carbon-based bifunctional ionomeric capacitive deionization (BICDI) system was successfully developed by applying a counter-charge ionomer layer to the BICDI electrode without the need of a monovalent ion exchange membrane (M-IEM) for the selective separation of mono/divalent ions. The counter-charge ionomer layer facilitates the selective separation of mono/divalent ions through a combination of mechanisms involving electrostatic repulsion, steric hindrance, and hydrophobic interactions. Meanwhile, the BICDI electrode matrix serves as an ion transport channel, enabling seamless ion transport and improving the electrosorption capacity of the electrode. SEM and EDS analyses have confirmed the presence of a counter-charge ionomer layer encapsulating the BICDI electrode. Notably, BICDI-C cell with counter-charge ionomer layer exhibits higher Li+ ion adsorption capacity and selectivity (321.6 μmol/g, βMg2+Li+=6.6) compared to commercial monovalent cation exchange membrane CDI (MCDI-C) cell (206.4 μmol/g, βMg2+Li+=1.4). The selectivity of the BICDI-C cell for mono/divalent ions can be optimized by adjusting various testing parameters, including flow rate, voltage, etc. More importantly, this versatile method is not only applicable for the separation of monovalent cation, but can also enhance the monovalent anion adsorption capacity and selectivity of BICDI-A (43.6 μmol/g, βSO42-Cl-=7.3) cell by incorporating a counter-charge ionomer layer onto the BICDI cathode. This approach allows for the efficient separation of both cationic and anionic species, broadening the range of potential applications for BICDI technology.

Heavy metal removal performance of capacitive deionization technology studied by machine learning

Capacitive deionization (CDI) technology is utilized for efficient treatment of industrial wastewater, characterized by low energy consumption and environmental protection. In order to comprehend the correlation between key experimental parameters and the electrosorption capacity (EC) of heavy metals in CDI technology, this paper employs a genetic algorithm (GA) to optimize a backpropagation artificial neural network (BPANN) for predicting the EC of CDI technology for heavy metal ions, with the characteristics of electrode materials converted into numerical characteristics for further analysis. Compared to the BPANN, the optimized GABPANN model demonstrates superior predictive accuracy. It achieves automatic adjustment of the hidden layer structure, neuron count, and transfer functions. Furthermore, the grey relational analysis indicates that the electrode material and the initial pH value of the solution are pivotal in determining the EC of heavy metal ions. This underscores the efficacy of machine learning (ML) algorithms in forecasting the nonlinear dynamics of CDI systems and elucidates the influence of individual parameters on the efficacy of heavy metal removal.

Hydrophilic porous activated biochar with high specific surface area for efficient capacitive deionization

Porous carbon electrode materials were prepared by carbonization and alkali activation from three natural porous biomasses, lotus petiole (LP), sunflower plate (SP), and lotus seedpod (LS). The pore structure, surface characteristics, and electrochemical properties of the three activated biochars were investigated and related to their CDI performance. The results indicated that the three activated biochars were hydrophilic and negatively charged, with a high specific surface area and an abundance of micropores. Due to the best surface wettability, highest specific capacitance, and shortest charge-discharge time, lotus petiole-based activated biochar (LPCK) had the highest electrosorption capacity of 8.67 mg·g−1 and faster desalination rate of 0.24 mg·g−1·min−1. Cyclic voltammetry and adsorption kinetics results indicate that the double-layer electrostatic adsorption mechanism dominated the CDI processes of the three activated biochars. The use of three biomass wastes provides low-cost, eco-friendly, and sustainable materials for the development of CDI electrodes.

Electrodeposition fabrication of graphene oxide/α-MnO2/polyaniline hierarchical porous electrodes with large hybrid specific capacitance for efficient U(VI) electrosorption

The radioactive pollution caused by the excessive discharge of uranium-containing wastewater generated from nuclear industry posed harmful effect to the ecological environment and human health. Herein, the electrodeposition of polyaniline on graphene oxide/α-MnO2 surface was conducted to fabricate novel hierarchical porous graphene oxide/α-MnO2/polyaniline (GMP) electrodes with large specific capacitance for U(VI) electrosorption through hybrid capacitance deionization (HCDI). As expected, the prepared GMP have high specific capacitance, small electrochemical impedance, and excellent electrosorption performance. Among the different GMP composites, GMP-2 presents the highest specific capacitance (303.85 F/g) and largest electrosorption capacity of U(VI) (330.41 mg/g at 0.9 V and pH4.0), indicating that its electrosorption capacity is closely related to the specific capacitance. Moreover, GMP-2 showed good selectivity for U(VI) electrosorption through pseudocapacitive mechanism. The XPS and FTIR characterization indicated that apart from hybrid capacitance (EDL and pseudocapacitance) mechanism, complexation and electrostatic interactions were also involved for U(VI) capture. The GMP-2 electrode is facile to fabricate and has excellent electrosorption performance, which could be used in HCDI for radioactive wastewater treatment.

Efficient and robust selective defluorination through capacitive deionization: Application of MOF-based Ti/N-doped activated porous carbon

Elimination of fluoride pollution in water is the key to improving the water quality. However, the traditional defluorination methods all have defects such as unsatisfactory results and complicated operation. In this study, we proposed an electrosorption method and prepared a Ti/N metal organic framework derived porous carbon electrode for efficient CDI defluorination. The experimental results showed that the prepared titanium-based porous carbon composites possessed better electrochemical activity and more efficient electrosorption capacity compared with the original materials. The electrosorption capacity of TiNC at 1.2 V was 33.99 mg F- g−1 in an initial solution of 50 mg F- L−1 within 2 h. We further analyzed the electrosorption behavior using adsorption kinetics and isotherm models, from which we can see that chemisorption played an important role in adsorption process. Finally, we elaborated fluoride electrosorption mechanism from the perspectives such as ligand exchange and electrostatic attraction. This study provides a new strategy for the defluorination technology.

Advancing towards technology readiness: Continuous-flow electrosorption for thorium separation from rare earth processing by-products

This study focuses on the development of a curated separation system aimed at separating thorium ions as part of a recovery plan for managing the thorium radionuclide in the rare earth element (REE) processing industry. As a step towards advancing technology readiness, the separation system employs the electrosorption technique, which involves the migration and storage of thorium ions in the electrical double layers on the porous surface of a carbon-based electrode. Using a prototype electrosorption cell operated at an applied voltage of 1.0 V, the system successfully achieved a thorium ion recovery rate of 84.5 ± 0.29 %, with an impressive electrosorption capacity of 105.26 mg-Th/1 g-carbon. Notably, despite the presence of higher concentrations of REE as competing ions, greater selectivity towards thorium was observed which likely attributable to its larger ionic radius, higher electron affinity, and greater distribution coefficient. These findings highlight the efficacy of the curated separation system and its potential to balance between REE economic significance as well as a protection to the environment.

Efficient recovery of gallium(Ⅲ) from alkaline solution by electrosorption using biomass-derived carbon aerogel electrodes

The effective extraction of gallium(Ⅲ) from alkaline solutions is a crucial strategy for the sustainable development of gallium resources. However, the conventional adsorption method is limited in terms of both the adsorption capacity and adsorption rate of gallium(Ⅲ). In this study, the optimal nitrogen-doped persimmon-powder activated carbon aerogel (NPAC) was prepared via optimizing synthesis conditions such as hydrothermal time, hydrothermal temperature, mass ratio of zinc chloride, and pyrolysis temperature to investigate the electrosorption effect of NPAC on gallium(Ⅲ). The results demonstrated that the electrode prepared from NPAC（NPAC@CF） exhibited exceptional electrochemical performance, attributed to the synergistic effect of reduced impedance, enhanced reversibility, and controlled capacitance (the capacitive contribution can be accurately quantified). At a bias voltage of 1.2 V, a pH of 11 and an initial concentration of NaGaO2 of 160 mg/L, the NPAC@CF electrode reached an outstanding electrosorption capacity of 250.69 mg g−1 for gallium(Ⅲ), which surpassed that of the conventional adsorption by over twofold. Electrosorption not only notably enhanced the adsorption capacity of NPAC for gallium(Ⅲ) but also elevated the adsorption rate, reducing the adsorption equilibrium time to just 40 min. The electrosorption mechanism of GaO2- on the surface of NPAC@CF was further understood by FTIR and XPS analyses, which mainly involved capacitive adsorption and the interaction of N/O-containing functional groups with GaO2-. Consequently, the electrosorption technology emerges as a promising, novel, and efficient approach for gallium extraction from alkaline solutions.

Iron-carbon composite as flow electrode active material for highly efficient electrosorption of uranium from radioactive wastewater

A kind of iron-carbon composite for efficient electrosorption of uranium from radioactive wastewater was prepared by simply carbonization of cellulose and ferric nitrate, and the uranium electrosorption performance and behavior of the iron-carbon composite as flow electrode active material were investigated for low-concentration (below 50 mg/L) uranium-containing wastewater. By regulating the experimental conditions such as cellulose particle sizes, the mass ratio of cellulose/Fe(NO3)3, liquid flow rate, pH, and electric field strength, it was found that under the optimized conditions, the uranium removal ratios were 66.8, 81.92, 95.2, and 97.75 % for initial concentrations of 0.1, 0.5, 5.0, and 50.0 mg/L, respectively. The uranium concentration could be reduced from 0.1 mg/L to 0.0332 mg/L (the emission standard is 0.05 mg/L in China, GB 8798–1996) within 180 min of treatment. In addition, the material maintained an average salt removal rate of 26.27 μg cm−2 min−1 after 36 cycles of electrosorption. It achieved a uranium removal ratio of 87 %, and the upper limit of the electrosorption capacity was still not reached. Combined with X-ray photoelectron spectroscopy (XPS) analysis, the results indicated that the uranyl ion (UO22+) was firstly adsorbed on the surface of the active material after entering the flow electrode. Then, parts of the UO22+(Ⅵ) were reduced to uranium dioxide [UO2(Ⅳ)] under the synergistic action of zero-valent iron (ZVI) and cathodic electro-reduction and were finally immobilized on the electrode surface. This study proposed an innovative application of iron-carbon composite as flow electrode active material in FCDI for the treatment of uranium-containing wastewater with low-concentration (below 50 mg/L).