Carbothermal synthesis of ordered mesoporous carbon-supported nano zero-valent iron with enhanced stability and activity for hexavalent chromium reduction

Nonmetallic modified zero-valent iron for remediating halogenated organic compounds and heavy metals: A comprehensive review

Zero Valent Iron (ZVI), an ideal reductant treating persistent pollutants, is hampered by issues like corrosion, passivation, and suboptimal utilization. Recent advancements in nonmetallic modified ZVI (NM-ZVI) show promising potential in circumventing these challenges by modifying ZVI's surface and internal physicochemical properties. Despite its promise, a thorough synthesis of research advancements in this domain remains elusive. Here we review the innovative methodologies, regulatory principles, and reduction-centric mechanisms underpinning NM-ZVI's effectiveness against two prevalent persistent pollutants: halogenated organic compounds and heavy metals. We start by evaluating different nonmetallic modification techniques, such as liquid-phase reduction, mechanical ball milling, and pyrolysis, and their respective advantages. The discussion progresses towards a critical analysis of current strategies and mechanisms used for NM-ZVI to enhance its reactivity, electron selectivity, and electron utilization efficiency. This is achieved by optimizing the elemental compositions, content ratios, lattice constants, hydrophobicity, and conductivity. Furthermore, we propose novel approaches for augmenting NM-ZVI's capability to address complex pollution challenges. This review highlights NM-ZVI's potential as an alternative to remediate water environments contaminated with halogenated organic compounds or heavy metals, contributing to the broader discourse on green remediation technologies.

Implementing magnetically-active Sn-based nanocomposites in hexavalent chromium removal from drinking water

A novel nanocomposite consisting of Fe3O4-loaded tin oxyhydroxy-chloride is demonstrated as an efficient adsorbent for the removal of hexavalent chromium in compliance to the new drinking water regulation. This study introduces a continuous-flow production of the nanocomposite through the separate synthesis of (i) 40 nm Fe3O4 nanoparticles and (ii) multilayered spherical arrangements of a tin hydroxy-chloride identified as abhurite, before the application of a wet-blending process. The homogeneous distribution of Fe3O4 nanoparticles on the abhurite's morphology, features nanocomposite with magnetic response whereas the 10 % loaded nanocomposite preserves a Cr(VI) uptake capacity of 7.2 mg/g for residual concentrations below 25 μg/L. Kinetic and thermodynamic examination of the uptake evolution indicates a relative rapid Cr(VI) capture dominated by interparticle diffusion and a spontaneous endothermic process mediated by reduction to Cr(III). The efficiency of the optimized nanocomposite was validated in a pilot unit operating in a sequence of a stirring reactor and a rotary magnetic separator showing an alternative and competitive application path than typical fixed-bed filtration, which is supported by the absence of any acute cellular toxicity according to human kidney cell viability tests.

Persulfate activation with biochar supported nanoscale zero- valent iron: Engineering application for effective degradation of NCB in soil

Nitrochlorobenzene (NCB) is very common in pesticide and chemical industries, which has become a major problem in soil environment. However, the remediation of NCB contaminated soil is received finite concern. Using biochar as a substrate for nanoscale-zero valent iron (nZVI/p-BC) to activate peroxodisulfate (PDS), a novel heterogeneous oxidative system had been applied in the current study to remediate NCB contaminants in soil. The degradation efficiencies and kinetics of m-NCB, p-NCB, and o-NCB by various systems were contrasted in soil slurry. Key factors including the dosage of nZVI/p-BC, the molar ratio of nZVI/PDS, initial pH and temperature on degradation of NCB were further examined. The results confirmed that the nZVI/p-BC/PDS displayed the remarkable performance for removing NCB compared with other systems. Higher temperature with nZVI/PDS molar ratio of 2:1 under the acidic condition favored the reduction of NCB. The treatment for NCB with optimal conditions were evaluated for the engineering application. The mechanism of nZVI/p-BC/PDS indicated that electron transfer between p-BC and nZVI was responsible for activation of PDS, generating active species (SO4•-, •OH and 1O2) via both the free and non-free radical pathways. Experimental results revealed prominent availability of nZVI/p-BC/PDS system in remediation of actual contaminated field by NCB.

In situ carbothermal synthesis of carbonized bacterial cellulose embedded with nano zero-valent iron for removal of Cr(VI)

Carbonized bacterial cellulose embedded with highly dispersed nano zero-valent iron (nZVI), denoted as nZVI@CBC, was prepared through one-step in situ carbothermal treatment of bacterial cellulose adsorbing iron(III) nitrate. The structure characteristics of nZVI@CBC and its performance in removing hexavalent chromium Cr(VI) were investigated. Results showed the formation of nZVI@CBC with a surface area of 409.61 m2/g at 800 °C, with nZVI particles of mean size 28.2 nm well distributed within the fibrous network of CBC. The stability of nZVI was enhanced by its carbon coating, despite some inevitable oxidation of exposed nZVI. Batch experiments demonstrated that nZVI@CBC exhibited superior removal efficiency compared to bare nZVI and CBC. Under optimal conditions, nZVI@CBC exhibited a high Cr(VI) adsorption capacity of up to 372.42 mg/g. Therefore, nZVI@CBC shows promise as an effective adsorbent for remediating Cr(VI) pollution in water.

One-step strategy for efficient Cr(VI) removal via phytate modified zero-valent iron: Accelerated electron transfer and enhanced coordination effect

The toxic Cr(VI) from industrial wastewater pose serious threat to the human beings and eco-systems. To reduce the operation processes and enhance the removal efficiency of Cr(VI), targeted design of functionalized material is critical in practical applications. Herein, we developed a one-step strategy for simultaneous Cr(VI) reduction and total Cr capture by a novel phytate modified zero-valent iron (PA-ZVI). The reaction kinetics of Cr(VI) removal by PA-ZVI (0.2225 min-1) was 53 times higher compared to ZVI (0.0042 min-1). The Fe(0) content on the surface of PA-ZVI increased from 2.2% to 15.6% compared to ZVI. Meanwhile, Cr(VI) was liable to adsorb on the surface of PA-ZVI due to its lower adsorption energy compared with the original ZVI (-2.09 eV vs -0.85 eV). The incorporation of the phytate ligand promoted electron transfer from iron core to Cr(VI), leading to the rapid in-situ reduction of Cr(VI) adsorbed on the surface of PA-ZVI to Cr(III). PA-ZVI exhibited a satisfactory performance for Cr(VI) removal at a broad pH range (3-11) and in the presence of coexisting ions and humic acid. Moreover, the reactor with the addition of PA-ZVI achieved more than 90% Cr(VI) removal within 72 h in continuous flow experiments. The feasibility of PA-ZVI for the removal of Cr(VI) is also validated in authentic wastewater. This work provides novel ZVI materials that can effectively address decontamination challenges from Cr(VI) pollution.

Enrichment and immobilization of heavy metal ions from wastewater by nanocellulose/carbon dots-derived composite

Heavy metal ions (HMIs) have been widely applied in various industries because of their excellent physicochemical properties. However, their discharging without appropriate treatment brought about serious pollution problems. So it is desirable but challenging to rapidly and completely clean up these toxic pollutants from water, especially utilizing environmentally friendly and naturally rich biomass materials. In this work, we prepared nanocellulose/carbon dots/magnesium hydroxide (CCMg) ternary composite using cotton via a simple hydrothermal method. The removal mechanism towards Cd2+ and Cu2+ was investigated using a combination of experimental techniques and density functional theory calculations. CCMg shows a good ability to remove HMIs. It is realized that the interaction between each component of CCMg and cadmium nitrate is mainly of hydrogen/dative bonds. Cadmium nitrate is preferentially enriched by the Mg(OH)2 moiety, proved by calculated thermodynamics, interfacial interactions and charges. After transformation, the cadmium carbonate precipitate is fixed on the surface by nanocellulose (NC) via chemical coupling; and of interest is that copper ion precipitates in the form of basic sulfate. Due to its high adsorption effect and simple recovery operation, CCMg is having a wide range of application prospects as a water treatment agent.

Confinement effect of network-structured carbon dots/cellulose nanocellulose/magnesium hydroxide for enhanced heavy metal ions capture and immobilization

To solve pollution problem of heavy metal ions (HMIs) and recover them for sustainable development, a high-efficient-sewage treatment agent, carbon dots/cellulose nanofiber/Mg(OH)₂ (CCMg), has been fabricated via a simple hydrothermal method. A variety of characterizations show that cellulose nanofiber (CNF) formed a layered-net structure. Hexagonal Mg(OH)₂ flakes of about 100 nm has been attached on CNF. Carbon dots (CDs) around 10-20 nm in size were produced from CNF and distributed along CNF. The extraordinary structural feature endows CCMg with high removal performance towards HMIs. The up-taken capacities reach 992.8 and 667.3 mg g^-1 for Cd²⁺ and Cu²⁺, respectively. The composite bears excellent durability in treating wastewater. Notably, the qualification of the drinking water can be satisfied while applying CCMg to handle Cu²⁺ wastewater. The mechanism of removal process has been proposed. Practically, Cd²⁺/Cu²⁺ ions were immobilized by CNF due to the space confinement effect. It achieves the facile separation and recovery of HMIs from the sewage, and more importantly, eliminates the risk of secondary contamination.

Efficient and reductive removal of bromate using a novel and stable nanoscale zero-valent iron embedded in N-doped carbon derived from metal-organic frameworks

Nanoscale zero-valent iron (nZVI) has drawn great interest in the remediation of contaminated waters. In this study, we prepared a novel and stable nZVI embedded in N-doped carbon matrix (nZVI@MOF-CN) using a facile direct carbonization method, in which an iron-containing metal-organic framework (MOF) served as both the iron and carbon sources, and melamine as the nitrogen source. The nZVI@MOF-CN composites were used in the removal of bromate in water, which could be effectively reduced by the surface electrons transferred from nZVI to the carbon encapsulation layer due to the Schottky-Mott effect. Doped nitrogen significantly facilitated the reduction of bromate by nZVI, because it enhanced the nZVI dispersion and bromate adsorption, and modulated the carbon matrix conductivity. The bromate reduction activity of nZVI@MOF-CN was more than 50 times higher that of its un-doped counterpart and a commercial nZVI. Moreover, owing to the protection of carbon encapsulation layer, nZVI@MOF-CN exhibited good stability and reusability. The leached concentration of iron ions of nZVI@MOF-CN was less than 5% of the commercial nZVI under the same reaction conditions. Commercial nZVI almost completely lost its bromate reduction activity after use (3% reduction efficiency in the examined time frame), while nZVI@MOF-CN maintained a reduction efficiency of 61%. The nZVI@MOF-CN could be effectively regenerated by hydrogenation reduction. After five reaction-regeneration cycles, nZVI@MOF-CN still achieved a bromate reduction efficiency of approximately 80%. These results suggest that MOF-derived nZVI materials are highly reactive and stable for the reductive removal of pollutants in water.

Enhanced removal performance of zero-valent iron towards heavy metal ions by assembling Fe-tannin coating

Heavy metals (HMs) pose serious threats to both human and environmental health and therefore, effective and low-cost techniques to remove HMs are urgently required. Here we report a facile Fe-tannin coating method for zero-valent iron (ZVI) including nanoparticles (nZVI) and foam (Fe_foam), and demonstrate that the generated Fe-tannin coating would remove the inherent passive iron oxide shell of ZVI and provide channels for the galvanic replacement reaction between ZVI and HM ions. Electrochemical characterizations demonstrate that the Fe core of the modified ZVI materials could be easily oxidized and transfer electrons to HM ions owing to the facile mass transport and charge transfer. In 40 min, nZVI@Fe-TA exhibits excellent performances for Cd(II), Ni(II), Pb(II), Hg(II), Cu(II) and Cr(VI) removal, with the apparent removal rate constants of 0.083, 0.085, 0.083, 0.073, 0.092 and 0.078 min^-1, respectively. It is found that the surface area normalized rate constants of nZVI@Fe-TA are 4-7 times higher than that of nZVI@Fe₂O₃ counterpart, suggesting that the improved HM removal reactivity of nZVI@Fe-TA is derived from the surface modification. Moreover, nZVI@Fe-TA has advantages in resisting interference and in the simultaneous removal of different HM ions. Under a 30 min hydraulic retention time, Fe_foam@Fe-TA could remove 98% HMs in the successive process. For real electroplating wastewater, Fe_foam@Fe-TA exhibits excellent performance for Cr(VI) and Ni(II) removal, producing effluent of stable quality that meets local emission regulation. This study provides a facile strategy to remove the inherent passive iron oxide shell and enhance the HM removal reactivity for ZVI materials.

Novel recycling of phosphorus-recovered incinerated sewage sludge ash residues by co-pyrolysis with lignin for reductive/sorptive removal of hexavalent chromium from aqueous solutions

Incinerated sewage sludge ash (ISSA), a by-product generated from the combustion of dewatered sewage sludge, has been extensively studied as a secondary resource for phosphorus recovery by acid extraction methods. Recycling of the P-recovered ISSA residues is crucial to complete and sustain the whole process. In this study, the ISSA residue rich in iron was reused and co-pyrolyzed with lignin at 650, 850 and 1050 °C under N₂ atmosphere for the synthesis of a composite material to remove hexavalent chromium (Cr(VI)) from aqueous solutions. Characterization analysis including XRD, XPS, and FTIR showed that iron oxides in the residue were reduced to zero valent iron at 1050 °C that exhibits the optimal Cr(VI) removal performance. The Cr(VI) removal process was rapid and reached a plateau at around 30 min. The maximum removal rate was obtained at pH 2.0, which was conducive for the treatment of a synthetic Cr(VI)-containing wastewater in fix-bed column experiments, whereby Cr(VI) as well as total Cr were continuously removed. Overall, this study proposed a new routine for the recycling of ISSA residue after phosphorus recovery by the acid extraction method and provided a value-added product for Cr(VI) removal from wastewaters.

A review of the new multifunctional nano zero-valent iron composites for wastewater treatment: Emergence, preparation, optimization and mechanism

Nano zero-valent iron (NZVI) with high chemical reactivity and environmental friendliness had recently become one of the most efficient technologies for wastewater restoration. However, the unitary NZVI system had not met practical requirements for wastewater treatments. Expectantly, the development of NZVI would prefer multifunctional NZVI-based composites, which could be prepared and optimized by the combined methods and technologies. Consequently, a systematic and comprehensive summary from the perspective of multifunctional NZVI-composite had been conducted. The results demonstrated that the advantages of various systems were integrated by multifunctional NZVI-composite systems with a more significant performance of pollutant removal than those of the bare NZVI and its composites. Simultaneously, characteristics of the product prepared by the incorporation of numerous methods were superior to those by a simple method, resulting in the increase of the entirety efficiency. By comparison with other preparation methods, the ball milling method with higher production and field application potential was worthy of attention. After combining multiple technologies, the effect of NZVI and its composite systems could be dramatically strengthened. Preparation technology parameters and treatment effect of contaminants could be further optimized using more comprehensive experimental designs and mathematical models. The mechanism of the multifunctional NZVI system for contaminants treatment was primarily focused on adsorption, oxidation, reduction and co-precipitation. Multiple techniques were combined to enhance the dispersion, alleviating passivation, accelerating electron transfer efficiency or mass transfer action for optimizing the effect of NZVI composites.

Green Synthesis of Nano-Zero-Valent Iron Using Ricinus Communis Seeds Extract: Characterization and Application in the Treatment of Methylene Blue-Polluted Water

In this study, the removal of methylene blue dye (MB) from aqueous solution was examined using a novel green adsorbent to overcome the obstacles encountered in chemical methods. Ricinus communis (RC) aqueous seeds extract was herein used as a reducing and capping agent to synthesize a novel nano-zero-valent iron (RC-nZVI) for the adsorption of harmful MB. Structural and morphological characterization of the synthesized RC-nZVI were performed using several techniques, e.g., steady-state absorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and zeta potential. The maximum efficiency of the removal was 96.8% at pH 6 and 25 °C. According to the kinetics study results, the adsorption process obeys the pseudo-first-order model. The experimental equilibrium data were fitted to the Freundlich isotherm model, the maximum adsorption capacity reached was 61.37 mg·g-1, and the equilibrium parameters were determined. The synthesized RC-nZVI possesses good reusability and can be considered as a potential economic and environmentally friendly adsorbent.

Removal of levofloxacin through adsorption and peroxymonosulfate activation using carbothermal reduction synthesized nZVI/carbon fiber

Nano zero-valent iron (nZVI) is widely used for decontamination. The main issues associated with nZVI are agglomeration and oxidation in the long term. In this study, the carbothermal reduction of cotton fiber was conducted for the synthesis of nZVI supported on cotton carbon fiber (nZVI/CF) to address the agglomeration and oxidation of nZVI. Synergistic adsorption and peroxymonosulfate (PMS) activation using nZVI/CF for removing levofloxacin (LEV) are reported herein. The nZVI concentration and morphology were conveniently adjusted by soaking cotton fiber in ferric nitrate solutions of various Fe³⁺ concentrations. The carbothermal reduction of the cotton fiber at 900 °C contributed to the reduction of Fe³⁺ into nZVI. A nZVI/CF-900-0.3 system was obtained through the carbothermal reduction of cotton fiber soaked in 0.3 M ferric nitrate. Favorable adsorption of nZVI/CF-900-0.3 to LEV facilitated LEV degradation under PMS activation. Approximately 93.83% of LEV (C₀ = 20 ppm) was removed within 60 min with 0.2 g/L of the catalyst and 1 mM PMS. It was preferable to use nZVI + CF-900 to activate PMS for degrading LEV, thus confirming the favorable effect of LEV adsorption on further degradation. The nZVI/CF-900-0.3 exhibited excellent long-term stability given that it was able to activate PMS after it was stored for 6 months. ·SO₄^- played an important role in LEV degradation in the presence of PMS.

Cu-Fe embedded cross-linked 3D hydrogel for enhanced reductive removal of Cr(VI): Characterization, performance, and mechanisms

Porous hydrogel, as a high-efficiency adsorbent for heavy metals, suffers the drawbacks of the use of expensive and toxic reagents during the process of preparation, further limiting its application ranges. Besides, the heavy metals couldn't be transformed into nontoxic species, which leads to the environmental pollution risk. Herein, a three-dimensionally (3D) structured Cu-Fe embedded cross-linked cellulose hydrogel (nFeCu-CH) was innovatively fabricated by a novel self-assembly and in-situ reduction method, which exhibited exceptionally enhanced adsorption-reduction property towards Cr(VI) wastewater. The results of degradation experiment exhibited that the removal reaction followed Langmuir-Hinshelwood first order kinetic model and the degradation rate constant decreased with solution pH and initial Cr(VI) concentration, while increased with nFeCu-CH dosage and temperature. Regeneration studies demonstrated that more than 88% of Cr(VI) was removed by nFeCu-CH even after five times of cycling. nFeCu-CH exhibited excellent reductive activity, which had a close connection with the superiority of 3D crosslinked architectures and bimetallic synergistic effect. And 97.1% of Cr(VI) could be removed when nFeCu-CH dosage was 9.5 g/L, pH was 5, initial concentration of Cr(VI) was 20 mg/L and temperature was 303 K. Combined with cellulose hydrogel not only could provide additional active sites, but also could restrain the crystallite growth and agglomeration of nano-metallic particles, leading to the promotion of Cr(VI) removal. In addition, coating with Cu facilitated the generation and transformation of electrons according to the continuous redox cycles of Fe(III)/Fe(II) and Cu(II)/Cu(I), leading to the further improvement of the reductivity of nFeCu-CH. Multiple interaction mechanisms including adsorption, reduction and co-precipitation between nFeCu-CH and Cr(VI) were realized. The current work suggested that nFeCu-CH with highly reactive sites, excellent stability and recyclability was considered as an potential material for remediation of Cr(VI) contaminated wastewater.

Modification of ordered mesoporous carbon for removal of environmental contaminants from aqueous phase: A review

Contamination of water bodies by potentially toxic elements and organic pollutants has aroused extensive concerns worldwide. Thus it is significant to develop effective adsorbents for removing these contaminants. As a new member of carbonaceous material families (activated carbon, biochar, and graphene), ordered mesoporous carbon (OMC) with larger specific surface area, ordered pore structure, and higher pore volume are being evaluated for their use in contaminant removal. In this paper, modification techniques of OMC were systematically reviewed for the first time. These include nonmetallic doping modification (nitrogen, sulfur, and boron) and the impregnation of nano-metals and metal oxides (iron, copper, cobalt, nickel, magnesium, and rare earth element). Reaction conditions (solution pH, reaction temperature, sorbent dosage, and contact time) are of critical importance for the removal performance of contaminants onto OMC. In addition, the pristine and modified OMC have been investigated for the removal of a range of contaminants, including cationic/anionic toxic elements and organic contaminants (synthetic dye, phenol, and others), and involving different and specific mechanisms of interaction with contaminants. The future research directions of the application of pristine and modified OMC were proposed. Overall, this review can provide sights into the modification techniques of OMC for removal of environmental contaminants.

ZVI impregnation altered arsenic sorption by ordered mesoporous carbon in presence of Cr(Ⅵ): A mechanistic investigation

It is challenging to efficiently remove arsenate (As(Ⅴ)) and chromate (Cr(Ⅵ)) simultaneously. Herein, ordered mesoporous carbon (OMC) was fabricated with averaged pore diameter of 6.5 nm and surface area of 997 m² g^-1. Zerovalent iron (ZVI) impregnation reduced surface area of ZVI/OMC (432 m² g^-1) and increased I_D/I_G ratio by 13%. Maximal Cr(Ⅵ) and As(Ⅴ) sorption capacities at pH 3 were 0.66 and 0.019 mmol g^-1 by OMC, and 0.71 and 0.39 mmol g^-1 by ZVI/OMC, respectively. Reduction accounted for over 55% for Cr(Ⅵ) and As(Ⅴ) removal followed by complexation and precipitation. Better ZVI/OMC performance was ascribed to higher electron transfer rate and lower electrical resistance than OMC as per electrochemical analysis. Upon Cr(Ⅵ) introduction, As(Ⅴ) removal increased to 0.28 mmol g^-1 by OMC, but decreased to 0.16 mmol g^-1 by ZVI/OMC. OMC could preferably reduce CrO₄^2- to Cr³⁺ by hydroxyl group, which enhanced its zeta potential facilitating As(Ⅴ) sorption. Regarding ZVI/OMC, Fe⁰ and Fe oxide in ZVI/OMC exhibited better affinity to As(Ⅴ), but the competition for the similar active sites resulted in compromised As(Ⅴ) and Cr(Ⅵ) removal. Thus, the novel OMC is advantageous for removal of binary As(Ⅴ) and Cr(Ⅵ), but ZVI/OMC is robust to detoxify single heavy metal.

Degradation of 2,4-DCP using persulfate and iron/E-carbon micro-electrolysis coupling system

The greenhouse gas carbon dioxide (CO₂) was converted to a novel CO₂ conversion material (electrolytic carbon, EC) by molten salt electrochemical conversion, which served as the carbon source to prepare an iron-carbon composite (Fe-EC). The composite was used to activate persulfate (PS) and degrade 2,4-dichlorophenol (2,4-DCP) in an aqueous solution. The effects of several essential operating parameters such as PS dosage and pH on 2,4-DCP degradation were investigated. The removal efficiency of 2,4-DCP (20 mg L^-1) was 97.8% in the presence of Fe-EC (50 mg L^-1) and PS (1 mmol L^-1). Moreover, the average % reaction stoichiometric efficiency (RSE) (calculated for all selected times 5-60 min) was maintained at 23.07%. Electron paramagnetic resonance (EPR), classical radical scavenging experiments, and density functional theory (DFT) calculations were integrated for a mechanistic study, which disclosed that the active species in the system were identified as SO₄^⦁-, •OH, and O₂^⦁-. Moreover, the iron-carbon micro-electrolysis/PS (ICE-PS) system had a high tolerance to a wide range of pH, which would provide theoretical guidance for the treatment of organic pollutants in practical industrial wastewater.

Carbothermal Synthesis of Ni/Fe Bimetallic Nanoparticles Embedded into Graphitized Carbon for Efficient Removal of Chlorophenol

The reactivity of nanoscale zero-valent iron is limited by surface passivation and particle agglomeration. Here, Ni/Fe bimetallic nanoparticles embedded into graphitized carbon (NiFe@GC) were prepared from Ni/Fe bimetallic complex through a carbothermal reduction treatment. The Ni/Fe nanoparticles were uniformly distributed in the GC matrix with controllable particle sizes, and NiFe@GC exhibited a larger specific surface area than unsupported nanoscale zero-valent iron/nickel (FeNi NPs). The XRD results revealed that Ni/Fe bimetallic nanoparticles embedded into graphitized carbon were protected from oxidization. The NiFe@GC performed excellently in 2,4,6-trichlorophenol (TCP) removal from an aqueous solution. The removal efficiency of TCP for NiFe@GC-50 was more than twice that of FeNi nanoparticles, and the removal efficiency of TCP increased from 78.5% to 94.1% when the Ni/Fe molar ratio increased from 0 to 50%. The removal efficiency of TCP by NiFe@GC-50 can maintain 76.8% after 10 days of aging, much higher than that of FeNi NPs (29.6%). The higher performance of NiFe@GC should be ascribed to the significant synergistic effect of the combination of NiFe bimetallic nanoparticles and GC. In the presence of Ni, atomic H* generated by zero-valent iron corrosion can accelerate TCP removal. The GC coated on the surface of Ni/Fe bimetallic nanoparticles can protect them from oxidation and deactivation.

Nano scale zero valent iron production methods applied to contaminated sites remediation: An overview of production and environmental aspects

The nano scale zero valent iron (nZVI) is the most used material in the remediation process. The inclusion of sustainability in the remediation process has also been gaining prominence. Sustainable remediation seeks to consider the environmental, economic and social impacts of remediation. Thus, this article aims to: (i) identify and describe nZVI production methods and (ii) evaluate their environmental aspects. Thus, this research was carried out in two stages. The first consisted of systematic bibliographical research to identify and describe nZVI production methods. In the second stage, an environmental analysis of the methods was performed considering the methodology of life cycle inventory assessment. Based on the inventory analysis, a classification of environmental aspects was performed, which included criteria, icons and a color scale. Nine nZVI production methods were identified, which comprised different technologies and processes. All methods had negative environmental aspects, such as high energy consumption, waste, wastewater generation and atmospheric emissions. In the classification of methods with regard to environmental aspects, the milling method had the best score, and the ultrasonic wave method the worst. Overall, this study contributes significantly to the detailed knowledge of nZVI synthesis methods in relation to production processes and their environmental aspects.

Porous biochar-nanoscale zero-valent iron composites: Synthesis, characterization and application for lead ion removal

Nano-zero-valent iron has been used in combination with a variety of support carriers to remove heavy metals in solution. However, pre-treatment of the carrier can reflect a better synergistic effect and thus achieve high heavy metal removal capabilities. In this study, the hydrophilic biochar obtained by an acid ammonium persulfate oxidation has an adsorption capacity of up to 135.4 mg g^-1 for Pb²⁺ (25 °C, pH = 6 with adsorbent amount of 10 mg and Pb²⁺ concentration of 50 mg L^-1). Due to the strong Fe-C-O covalent bond, nZVI increases the binding force with the carbon matrix. Benefitting from the high specific surface area, porous structure and rich oxygen-containing functional groups, the resultant nZVI-HPB samples are favourable for Pb²⁺ diffusion and adsorption, exhibiting maximum adsorption capacity of 480.9 mg g^-1 (pH = 6, 25 °C with adsorbent amount of 10 mg and Pb²⁺ concentration of 200 mg L^-1). The multiple interaction mechanisms in the Pb²⁺ removal process such as the reduction reaction, complexation and co-precipitation proceed simultaneously are concluded by the analyses of Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) spectra.

Removal of Cr(VI) and methyl orange by activated carbon fiber supported nanoscale zero-valent iron in a continuous fixed bed column

The application of activated carbon fiber supported nanoscale zero-valent iron (ACF-nZVI) in the continuous removal of Cr(VI) and methyl orange (MO) from aqueous solution was studied in depth. The breakthrough curves of Cr(VI) in a fixed bed with ACF-nZVI were measured, and compared with those in the fixed bed with ACF. The catalytic wet peroxide oxidation (CWPO) process for MO was also carried out using ACF-nZVI after reacting with Cr(VI) in the same fixed bed. The results showed that the breakthrough time of ACF-nZVI was significantly longer than that of ACF. Higher pH values were unfavorable for the Cr(VI) removal. The breakthrough time increased with decreasing inlet Cr(VI) concentration or increasing bed height. The Yoon-Nelson and bed depth service time (BDST) models were found to show good agreement with the experimental data. The Cr(VI) removal capacity when using ACF-nZVI was two times higher than that when using ACF. Under the optimal empty bed contact time of 1.256 min, the fixed bed displayed high MO conversion (99.2%) and chemical oxygen demand removal ratio (55.7%) with low Fe leaching concentration (<5 mg/L) after continuous running for 240 min. After three cycles, the conversion of MO remained largely unchanged.

Investigation of a modified metal-organic framework UiO-66 with nanoscale zero-valent iron for removal of uranium (VI) from aqueous solution

A novel composite material (nZVI/UiO-66) of nanoscale zero-valent iron (nZVI) with a functionalized metal-organic framework was synthesized by this study via a coprecipitation method, which was used for the efficient removal of U(VI) in the aqueous solution. The nZVI/UiO-66 had an excellent removal capacity of 404.86 mg g^-1 with an initial U(VI) concentration of 80 mg L^-1, 313 K and pH = 6. The transmission electron microscopy (TEM) revealed that nZVI particles were inhomogeneously distributed on the surface of UiO-66. The analysis by the X-ray diffraction (XRD) has further illustrated that the introduction of nZVI did not change the structure of UiO-66. The adsorption process closely followed the pseudo-second-order kinetic and the Freundlich isotherm model. The removal process of U(VI) by nZVI/UiO-66 was spontaneous and endothermic. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses have illustrated that the mechanism was mainly related to adsorption of U(VI) from UiO-66 and reduction of U(VI) by nZVI. The Zr-O bonds were shown to play a vital role in the uranium removal. nZVI/UiO-66 could be recycled. The uptake rate could be maintained at around 80% after 5 cycles of use. Therefore, these results manifested that the nZVI/UiO-66 is a promising sorbent for the efficient and selective removal of U(VI) in radioactive wastewaters.

Enhancing Cr(VI) reduction and immobilization by magnetic core-shell structured NZVI@MOF derivative hybrids

Hexavalent chromium (Cr(VI)) has significantly threatened the environmental health because of its distinct toxicity. A novel magnetic core-shell structured NZVI@ZD composite was designed for simultaneous adsorption and reduction of Cr(VI). NZVI@ZD was synthesized by carbonization of the as-prepared core-shell structure NZVI@zeolitic imidazole framework-67 (ZIF-67). After carbonization, the original ZIF-67 shell shape was preserved well with marginal parts developing to graphitized carbon. Both cobalt (Co) and NZVI nanoparticles were finely dispersed in the porous ZIF-67 derivative (ZD). NZVI@ZD exhibited excellent removal performance for Cr(VI), owing to its high specific surface area and large pore size favorable for Cr(VI) adsorption and diffusion. The maximum adsorption capacity of NZVI@ZD for Cr(VI) was surprisingly as high as 226.5 mg g^-1, surpassing the pristine ZIF-67 (29.35 mg g^-1) and NZVI@ZIF-67 (36.53 mg g^-1). Zeta potential and X-ray photoelectron spectroscopy (XPS) spectra revealed that electrostatic attraction, reduction and precipitation might be involved in the Cr(VI) removal process by NZVI@ZD, resulting in the conversion of the adsorbed Cr(VI) to Cr(III) of lower toxicity and an eventual immobilization on the NZVI@ZD. The magnetic core-shell structured NZVI@ZD possessed superior adsorptive reactivity for Cr(VI) to most other traditional or newly reported materials, thus should be deemed highly efficient for Cr(VI)-contaminated wastewater treatment.

A novel stabilized carbon-coated nZVI as heterogeneous persulfate catalyst for enhanced degradation of 4-chlorophenol

Nano zero-valent iron (nZVI) and its composite materials have been extensively studied in the field of environmental remediation. However, the oxidation and agglomeration of nZVI limits the large-scale application of nZVI in environmental remediation. This study developed a two-step method to prepare stable carbon-coated nZVI (Fe⁰@C) which combined hydrothermal carbonization and carbothermal reduction methods and used glucose and iron oxide (Fe₃O₄) as precursors. When the carbothermal reduction temperature was 700 °C and the elemental molar ratio of carbon to iron was 22:1, stable Fe⁰@C can be generated. The nZVI particles are encapsulated by mesoporous carbon and embedded in the carbon spheres. The unique structure of carbon coating not only inhibits the agglomeration of nZVI, but also makes nZVI stable in air for more than 120 days. Not only that, the as-synthesized Fe⁰@C exhibited high catalytic activity toward the degradation of 4-chlorophenol (4-CP) by activating persulfate. Different from conventional nZVI catalysts in generation of sulfate radicals, Fe⁰@C selectively induced hydroxyl radicals for 4-CP degradation. Moreover, Fe⁰@C has been shown to efficiently degrade 4-CP by using the dissolved oxygen in water to form hydroxyl radicals. This study not only provides a simple, green method for the preparation of stabilized nZVI, but also provides the possibility of large-scale application of nZVI in the field of environmental remediation.

Degradation of orange II by Fe@Fe2O3 core shell nanomaterials assisted by NaHSO3

Fe@Fe₂O₃ core shell nanomaterials with different Fe₂O₃ shell thickness were synthesized and the Fe@Fe₂O₃/NaHSO₃ Fenton-like system was used for the decomposition of Orange II. The consequences are compared with traditional Fenton Fe@Fe₂O₃/H₂O₂ system. The Fe@Fe₂O₃/NaHSO₃ system showed extremely good applicability under both strongly acidic and alkaline conditions. The new Fe@Fe₂O₃-(2)/NaHSO₃ system led to more than 99% degradation in 30 s when the pH was 3, which indicated that the Fe@Fe₂O₃ material was not corroded during the process even under strongly acidic condition. The above Fe@Fe₂O₃-(2) material was prepared from nano-zero-valent iron aged in solution for 2 h to synthesize the Fe₂O₃ shell. The reaction mechanism of Fe@Fe₂O₃/NaHSO₃ Fenton-like system was also concluded. The oxidation efficiency was highly improved due to rapid electron transfer between Fe core and Fe₂O₃ shell, which promoted the direct recycling of ≡Fe³⁺ and ≡Fe²⁺ and thus accelerated the generation of SO₄^- and OH radicals.

High-dispersion zero-valent iron particles stabilized by artificial humic acid for lead ion removal

Nano zero-valent iron (nZVI), as a high-efficiency adsorbent for heavy metals, often suffers being oxidized and assembling together due to small size and super reactivity, further decreasing its adsorption performance and limiting application ranges. Herein, we have designed a novel adsorbent with high-dispersion nZVI stabilized by as-prepared artificial humic acid (AHA-nZVI) derived from hydrothermal humification (HTH) technology. Introduction of artificial humic acid (A-HA) can effectively reduce the oxidation and agglomeration of nZVI, leading to superior kinetic removal efficiency of Pb²⁺ (> 99.2%) and huge Langmuir removal capacity of 649.0 mg/g. The combination of nZVI and A-HA (contained abundant functional groups, i.e. -OH and -COOH) via C-O-Fe bonding makes nZVI have good dispersion and oxidation resistance. Multiple interaction mechanisms including reduction reaction, complexation and co-precipitation between heavy metals and AHA-nZVI samples are realized. Overall, AHA-nZVI is a promising material for high-performance heavy metal contaminated water treatment.

A novel composite of almandine supported humboldtine nanospheres, in situ synthesized from natural almandine, possesses high removal efficiency of Cr(Ⅵ) over a wide pH range

Preparing a cost-effective material which can been applied in a wide pH range is very crucial for the remediation of Cr(Ⅵ) polluted water. In this study, a novel material, almandine/humboldtine nanospheres (AHN) composites, was synthesized directly from almandine by one-pot method. Characterizations of XRD and SEM/TEM showed that the structure changes of almandine to nano-humboldtine leaded to significant increase of Cr(Ⅵ) removal capacities. And 96.45% of Cr(Ⅵ) was removed by AHN-24 composite at pH value of 3, initial Cr(Ⅵ) concentration of 20 mg/L, temperature of 298.15 K and dosage of 0.6 g/L. Furthermore, Cr(Ⅵ) removal capacity was only decreased from 48.23 mg/g to 34.33 mg/g when the initial pH value increased from 3 to 11, which demonstrated that the synthesized composite had a wide pH application range in Cr(Ⅵ) removal. The thermodynamic parameters (ΔG⁰ < 0, ΔH⁰ > 0 and ΔS⁰ > 0) illustrated that Cr(VI) removal process was spontaneous and endothermic. FTIR and XPS revealed that the Cr(Ⅵ) removal mechanisms included reduction-precipitation and reduction-complexation. Combined with cost analysis, all of results implied that the synthesized composites were a high efficient and low cost material for Cr(Ⅵ) pollution remediation in a wide pH range.

Almond Shell-Derived, Biochar-Supported, Nano-Zero-Valent Iron Composite for Aqueous Hexavalent Chromium Removal: Performance and Mechanisms

Nano-zero-valent iron biochar derived from almond shell (nZVI-ASBC) was used for hexavalent chromium (CR) removal. Experiments showed that pH was the main factor (p < 0.01) that affected the experimental results. At a dosage of 10 mg·L⁻¹ and pH of 2–6, in the first 60 min, nZVI-ASBC exhibited a removal efficiency of 99.8%, which was approximately 20% higher than the removal yield at pH 7–11. Fourier transform infrared spectroscopy results indicated N-H was the main functional group that influenced the chemisorption process. The pseudo second-order dynamics and Langmuir isotherm models proved to be the most suitable. Thermodynamic studies showed that the reaction was exothermic and spontaneous at low temperatures (T < 317 K). Various interaction mechanisms, including adsorption and reduction, were adopted for the removal of Cr(VI) using the nZVI-ASBC composite. The findings showed that the BC-modified nZVI prepared with almond shell exerts a good effect and could be used for the removal of Cr(VI).

Adsorptive and Reductive Removal of Chlorophenol from Wastewater by Biomass-Derived Mesoporous Carbon-Supported Sulfide Nanoscale Zerovalent Iron

Chlorinated compounds in a water environment pose serious threats to humanity. A nanoscale zerovalent iron (nZVI) has desirable properties for water dichlorination, but its reactivity is still limited by agglomeration and oxidation. In this study, the mesoporous carbon (MC) derived from biomass waste was prepared for immobilizing nZVI, and the nZVI@MC was further modified by sulfur (S-nZVI@MC) to relieve surface oxidation. The synergistic effect between nZVI and surface modification, the reaction conditions and the removal mechanism were investigated systematically. The characterization results showed nZVI was successfully loaded on the surface of MC, and the aggregation of nZVI was prevented. Moreover, sulfidation modification resulted in the formation of FeS on the surface of nZVI, which effectively alleviated surface oxidation of nZVI and promoted the electron transfer. Batch experiments demonstrated S-nZVI@MC had greatly enhanced reactivity towards 2,4,6-trichlorphenol (TCP) as compared to MC and nZVI, and the removal rate could reach 100%, which was mainly attributed to the significant synergistic effect of MC immobilization and sulfidation modification. Furthermore, the TCP removal process was well described by a Langmuir adsorption model and pseudo-second-order model. The possible mechanism for enhanced removal of TCP is the fast adsorption onto S-nZVI@MC and effective reduction by S-nZVI. Therefore, with excellent reducing activity and antioxidation, S-nZVI@MC has the potential as a pollutant treatment.

Carbothermal preparation of magnetic-responsible ferrihydrite based on Fe-rich precipitates for immobilization of arsenate and antimonate: Batch and spectroscopic studies

The present study provides the starch-mediated carbothermal preparation of magnetic-responsible ferrihydrite (MFHP) based on Fe-rich precipitates which is recovered by mine drainage for immobilization of arsenate and antimonate in water. Fe K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) represented partial transformation from ferrihydrite to magnetite in MFHP due to the carbothermal reduction process, resulting in an effective saturation magnetism (= 19.2 emu/g). As and Sb K-edge EXAFS revealed that arsenate ion combines onto the surface of MFHP as inner-sphere binuclear bidentate surface complex, and antimonate forms inner-sphere mononuclear bidentate complex. In addition, the leachability by toxicity characteristic leaching procedure (TCLP) implies the environmental friendly preparation method for preparing magnetic-responsible adsorbents using mining waste.

Simultaneously implement of both weak magnetic field and aeration for ciprofloxacin removal by Fenton-like reaction

This study evaluates the ability of heterogeneous Fenton-like reaction (nano zero-valent iron (NZVI)/H₂O₂) in combination with weak magnetic field (WMF) under continuous oxygen supply by air bubbling for pollutant abatement (using ciprofloxacin as a model pollutant). The considered operating variables were initial pH, catalyst dosage, reaction time and different intensities of magnetic field. Results indicated that NZVI/H₂O₂/aeration/weak magnetic field could effectively decompose ciprofloxacin at neutral condition and higher removal rates are observed at higher pH and NZVI concentrations. Superimposing a weak magnetic field leads to 20% enhancement in ciprofloxacin removal by catalytic Fenton under aeration condition. Employing simultaneously magnetic field induction and aeration exhibit excellent capability to the NZVI oxidation and significantly increased the dissolution rate of iron. Based on Fourier transform infrared spectroscopy, transformation products of NZVI are Fe₃O₄ and FeO(OH). The faster mass transport due to Lorentz and field gradient force, more oxygen diffusion to the iron surface and promoted electrochemical reactions results in more OH° production. Generation of weak magnetic field by permanent magnets and using aeration for both mixing and in situ oxygen supply significantly enhanced the Fenton reaction performance. This combination technology doesn't need any energy input and costly chemicals hence can be used easily for wastewater treatment applications.

Nanoscale zero valent iron supported on MgAl-LDH-decorated reduced graphene oxide: Enhanced performance in Cr(VI) removal, mechanism and regeneration

The scaled application of nanoscale zero-valent iron nanoparticles (nZVI or Fe° NPs) in environmental remediation is challenged by easy surface passivation and particle aggregation. To improve this situation and enhance their performance in Cr(VI) removal from water phase, we present one novel strategy to hybridize nZVI with layered double hydroxide (LDH) decorated reduced graphene oxide (rGO). The as-prepared ternary (Fe@LDH/rGO) composites possess better dispersibility, improved hydrophilicity and more positive surfaces that allows higher removal efficiency and capacity for Cr(VI) oxyanions. Composition proportion are optimized and influences of surroundings (solution pH, Cr(VI) concentration and temperature) are evaluated. Also, we demonstrate that Fe@LDH/rGO can be reused with suitable post-treatments, which combines alkaline solution desorption and NaBH₄ revivification possess. Cr desorption and Fe leaching ratio during regeneration should be critical indicators that determine the recovery efficiency. Synergistic effect within this ternary system not only contributes to its superiorities in stability, but also continuous iron corrosion via the formation of micro Fe-C batteries, where rGO acts as cathode and alternative electron conductor. The present work suggests great potentials of Fe@LDH/rGO composites in groundwater remediation.

Facile modification of activated carbon with highly dispersed nano-sized α-Fe2O3 for enhanced removal of hexavalent chromium from aqueous solutions

Activated carbon-coated α-Fe₂O₃ nanoparticles (nFe₂O₃@AC) were synthesized by a facile impregnation method to enhance hexavalent chromium (Cr(VI)) removal from water. The SEM images confirmed that α-Fe₂O₃ particles ranging from 90 to 500 nm were dispersedly loaded on the AC, which successfully amended Cr(VI) removal. The nFe₂O₃@AC was able to remove Cr(VI) with a 3 times higher efficiency of 94% in comparison with the AC. After adsorption, Cr(VI) reduction coupled with AC oxidation and low soluble (Cr_xFe_1-x)(OH)₃ precipitates were eventually formed. The Cr(VI) removal process was pH-dependent and could be well fitted to pseudo second-order kinetics. The nFe₂O₃@AC could be easily regenerated by 0.1 M HCl and showed a good stability as an 80% Cr(VI) removal efficiency was recorded after 4 desorption-adsorption cycles. In addition, this composite had a promising potential for repeated utilization because the AC of the adsorbed nFe₂O₃@AC could be refreshed and remodified with nFe₂O₃ after stripping all the nFe₂O₃ and (Cr_xFe_1-x)(OH)₃ precipitates from its surface by 1 M HCl and a Cr(VI) removal efficiency of 86% could be achieved. Our results demonstrated that the use of nFe₂O₃ is an efficient and promising method to modify AC and enhance Cr(VI) removal form aqueous solutions.

Highly efficient immobilization of NZVI onto bio-inspired reagents functionalized polyacrylonitrile membrane for Cr(VI) reduction

To provide superior substrates and determine the specific species of immobilized nano zero-valent iron (NZVI) system, polyacrylonitrile (PAN) membrane was functionalized by bio-inspired polydopamine (PDA) and poly(_l-DOPA) (PDOPA) for efficient immobilization of NZVI. The synthesized composites were denoted as PAN/PDA-NZVI (PPN) and PAN/PDOPA-NZVI (PON), respectively. Analyses of XRD, SEM/EDS and XPS show that the aggregation and release of iron nanoparticles had been successfully controlled by improving membrane hydrophilcity and iron-chelating capacity via the graft of functionalized groups (i.e. OH and COOH) of PDA and PDOPA on PAN membrane. Both PPN and PON composites exhibited superior reactivity for Cr(VI) removal (Cr(VI) removal efficiency and reaction rate were 2.21-2.22 and 9.90-10.14 times higher than that of bare NZVI, respectively). The stability and recyclability of PPN and PON composites could be maintained over repeated cycles. Further analyses indicate that PON is more capable for Cr(VI) elimination than PPN due to the proprietary carboxyl of _l-DOPA. With the addition of 1,10-phenanthroline, membrane-chelated Fe(II) was determined to be the major species in Cr(VI) removal system, accounting for 56.9% and 53.8% with regard to PPN and PON composites, and Fe⁰ was responsible for the reduction of residual Cr(VI). Analyse of reacted composites revealed that Cr(VI) was completely converted into Cr(III), followed by formation of dominant Cr(III)/Fe(III) (oxy)hydroxides and partial desorption from NZVI reactive sites. This study suggested that both synthesized PPN and PON composites have potentials for Cr(VI)-contaminated wastewater treatment.

Sustaining the efficiency of the Fe(0)/H2O system for Cr(VI) removal by MnO2 amendment

This study aims to provide new knowledge regarding the effect of MnO₂ co-presence on efficiency of Cr(VI) removal with Fe(0). Non-disturbed batch experiments (≤40 days) were conducted using two types of Fe(0) (milli- and micro-sized), two Cr(VI) concentrations (5 and 100 mg/L), in three different systems ("Fe(0) only", "MnO₂ only", and "Fe(0) + MnO₂"), at an initial pH value of 6.9. Compared to "Fe(0) only" system, the efficiency and rate of Cr(VI) removal were highly promoted in "Fe(0) + MnO₂" system; moreover, while for the "Fe(0) only" system removal of Cr(VI) was severely hindered by increasing Cr(VI) concentration, in "Fe(0) + MnO₂" system comparable high efficacies were noticed both at low and high concentration. Recycling experiments indicated that total Cr(VI) removal capacity of "Fe(0) + MnO₂" system was up to 48.1 times greater than of the "Fe(0) only" system. Enhanced removal of Cr(VI) with Fe(0) was achieved at low doses of MnO₂, with an optimal mass ratio Fe(0):MnO₂ of 4:1. The favorable synergistic effect observed in "Fe(0) + MnO₂" system was ascribed to capacity of MnO₂ to accelerate Fe(0) oxidative dissolution, and to generate supplementary amounts of secondary adsorbents/reductants with removal ability towards Cr(VI). This study provides compelling evidence that "Fe(0) + MnO₂" system could represent a highly efficient and cost-effective alternative for the abatement of Cr(VI) aqueous pollution.

Removal of tridecane dicarboxylic acid in water by nanoscale Fe0/Cu0 bimetallic composites

In this study, nanoscale zerovalent Fe⁰/Cu⁰ bimetallic composites were synthesized by liquid-phase reduction of Fe(II)/Cu(II) and applied for decomposition of tridecane dicarboxylic acid (DC13). The removal performance of Fe⁰/Cu⁰ bimetallic composites for DC13 in terms of Fe/Cu ratios, addition amount, reaction time and initial pH were studied. The as-prepared nanoscale composites were characterized by a transmission electron micrographs (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area, fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma-atomic emission spectrometry (ICP). Finally, the degradation mechanisms of DC13 utilizing the Fe⁰/Cu⁰ nanocomposites were investigated by using mass spectrumetry (MS). The results indicated that the Fe⁰/Cu⁰ bimetallic composites exerted a remarkable removal capacity for DC13 through the multiple reactions, e.g., coagulation, adsorption and •OH reduction in the Fe⁰/Cu⁰ system. XPS indicated that the Fe⁰/Cu⁰ reduction reaction of hydroxyl radicals (•OH) system played a significant role in degradation of DC13 and the LC-MS result suggested that DC13 was degraded into inorganic small molecules by •OH radicals generated from the corrosion of Fe⁰. The experimental results indicated that the nanoscale Fe⁰/Cu⁰ could be used as a potential material to remove DC13 because of its remarkable degradability.