Cr Transport Research Articles

Physiological, biochemical, and genomic elucidation of the Ensifer adhaerens M8 strain with simultaneous arsenic oxidation and chromium reduction

This study reports the simultaneous oxidation of As(III) and reduction of the Cr(VI) strain Ensifer adhaerens M8 screened from soils around abandoned gold tailings contaminated with highly complex metals (loids). Physiological, biochemical, and genomic techniques were used to explore the mechanism. The strain M8 could simultaneously oxidize 1 mM As(III) and reduce 45.3 % 0.1 mM Cr(VI) in 16 h, and the Cr(VI) reduction rate was increased by 5.8 % compared with the addition of Cr(VI) alone. Cellular debris was the main site of M8 arsenic oxidation. Chromium reduction was dominated by the reduction of extracellular hexavalent chromium (23.80–35.67 %). The genome of M8 included one chromosome and four plasmids, and a comparison of the genomes showed that M8 had two more plasmids than strains of the same genus, which may be related to strong environmental adaptations. M8 had 10 heavy metal resistance genes (HMRs), and plasmid D had a complete cluster of arsenic resistance-oxidation-transport genes (arsOHBCCR-aioSR-aioBA-cytCmoeA-phoBBU-PstBACS-phnCDEE). The genes involved in Cr(VI) detoxification include DNA repair (RecG, ruvABC, and UvrD), Cr(VI) transport (chrA, TonB, and CysAPTW) and Cr(VI) reduction. In summary, this study provides a molecular basis for As (III) and Cr (VI) remediation.

RETRACTED: Treatment mechanism of hexavalent chromium wastewater in constructed wetland-microbial fuel cell coupling system

Cr(VI) is toxic to the human body and environment. As a suitable wastewater treatment with low energy requirement technology, constructed wetland-microbial fuel cells (CW-MFCs) can treat Cr(VI) wastewater while generating electricity. In this study, CW-MFC and constructed wetland systems were developed to purify Cr(VI) wastewater. The removal mechanism of Cr(VI) was examined by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy. The results demonstrated that the average pollutant removal efficiency of the CW-MFC system is 2.99–8.13% higher than that of the constructed wetland system, and the maximum power density is 505.61 mW m−2. Moreover, the XPS and EPR analyses demonstrated that Cr in substrates and Leersia hexandra Swartz primarily is in the form of Cr(III). Moreover, in plants and substrates, the Cr(III) content of the CW-MFC system was higher than that of the control, and the bioconcentration and translocation factors were 0.23 and 0.05 higher than those in the control group, respectively. Therefore, the CW-MFC system can efficiently remove Cr(VI) and promote the accumulation and transport of Cr. Microbial community diversity in the CW-MFC was significantly higher than CW. The abundance of electrogenic bacteria Geobacter and metal dissimilatory reducing bacteria Acinetobacter in CW-MFC is higher than that in CW. To summarize, the study results provide a theoretical basis for the mechanism study of Cr(VI) wastewater treatment using CW-MFC systems.

Biochar colloids facilitate transport and transformation of Cr(VI) in soil: Active site competition coupling with reduction reaction

Biochar has been demonstrated as an efficient amendment for immobilizing contaminants. However, a certain number of micro/nano-scale particles are inevitably present in the fresh or aged biochar, which may facilitate the downward transport of contaminants along the soil profile, posing a detrimental impact on the groundwater. Herein, the effects of biochar colloids derived from wood chip and wheat straw at two temperatures (350 °C and 500 °C) on the transport and transformation of Cr(VI) in soil were investigated. All biochar colloids facilitated the transport of Cr(VI) in a loam clay Ultisol, which was attributed to the competition between biochar colloids and Cr(VI) for the available sorption sites on the soil surface. Wheat straw biochar colloids caused more transport of Cr(VI) than wood chip ones due to the more negative charge and higher polarity, which resulted in stronger electrostatic repulsion and competition with Cr(VI). It is soluble Cr(VI) that dominated the transport of Cr in the effluent solution, however, the particulate Cr(VI) could be reduced into Cr(III) before being carried by biochar colloids for co-transport. The 350 °C biochar colloids had higher electron donating capacities than 500 °C ones, resulting in more reduction of Cr(VI) and more co-transport as biochar colloids-associated Cr(III) in the effluent. Moreover, the more negatively charged 350 °C biochar colloids could also attach more soil Fe oxides, further facilitating the cotransport of Cr via the formation of a binary or ternary complex. Modeling showed the experimental-consistently results that biochar colloids caused 0.5–7.0 times faster transport of Cr(VI) than no biochar colloids in the long-term period. Our findings demonstrate that biochar colloids can enhance transport and transformation of Cr(VI) in soils, which arouse migration risk concern about in-situ remediation of Cr(VI)-contaminated soils by biochar.

Sensitivity Analysis for Modeling of Cr(VI) Transfer From Soil to Surface Runoff

Heavy metal contamination in soil has become a serious environmental problem in China, and chromium is one of the major threats to human health. In order to better understand the transfer pattern of heavy metal hexavalent chromium from polluted sites into surface water, the influencing factors that affect solute transfer from soil into the surface runoff with linear and nonlinear adsorption equations based on a two-layer incomplete mixing model were analyzed in this study. The Quasi-Newton method was used to optimize model parameters by fitting with the experimental laboratory data of chromium (Cr(VI)) in surface runoff. The local sensitivity analysis and the Morris global sensitivity analysis approaches were used to assess the parameter importance of rainfall intensity p, the thickness of the mixing layer hmix, incomplete mixing parameter α and γ, the soil adsorption parameters, and the initial soil water content θ0. The study results showed that the optimized nonlinear models were better consistent with the experimental results than the linear adsorption equation model. The results of global sensitivity indicated that rainfall intensity p was the main factor influencing Cr(VI) transport from the soil into surface runoff. The hmix and the α in the two-layer model were vital parameters that influenced such transport processes. Moreover, the soil adsorption properties and the θ0 had the lowest effects on runoff Cr(VI) loss. The results indicate that for controlling pollution migration in surface runoff, it is essential to focus on the analysis of precipitation conditions and soil properties that control the thickness of the mixing layer and the degree of mixing.

Biomass production and uptake of sulfur, chromium and micronutrients by Tanzania guinea grass grown with sulfur and chromium.

Soil contamination caused by improper waste disposal can affect plant growth. Tropical forage plants have rapid growth, high biomass production and vigorous regrowth. Chromium (Cr) is one of the most common contaminants in the environment. Sulfur (S) is a nutrient involved in various cell detoxification processes. The objective was to assess the effects of excess Cr on biomass production and concentrations of this metal, S and cationic micronutrients, under conditions of varying supply of S for Tanzania guinea grass. The experiment was conducted in randomized complete blocks in a 3 × 4 factorial scheme, corresponding to three levels of S (0.1, 1.9 and 3.7mmol L-1) and four levels of Cr (0.0, 0.5, 1.0 and 2.0mmol L-1) in three replicates. Root surface area, shoot and root biomass production, concentrations of total S, sulfate-S, Cr and cationic micronutrients, and Cr transport factor were determined. S level of 1.9mmol L-1 reduced the toxicity by Cr in Tanzania guinea grass, expressed by the higher shoot and root dry weight production, greater stability in the cellular concentration of sulfate-S and higher concentrations of micronutrients. It was concluded that the high availability of S reduced the toxicity by Cr(VI) in Tanzania guinea grass, expressed by the higher shoot and root dry weight production, greater stability in the cellular concentration of sulfate-S and higher concentration of micronutrients in the grass shoots.

PVC/EVA-based polymer inclusion membranes with improved stability and Cr(VI) extraction capacity: Water plasticization effect

Polymer inclusion membranes (PIMs) are far investigated for their ability to extract heavy metals and small organic compounds from aqueous media. Polyvinyl chloride (PVC) is one of the most widely used base polymers for the PIM elaboration. However, its use requires the incorporation of a relatively expensive liquid plasticizer. In the present work, poly(ethylene-co-vinyl acetate) (EVA) serves as a polymer plasticizer for the elaboration of PIMs based on PVC as a base polymer and Aliquat 336 as a carrier. The composition of PIMs was optimized in terms of the PVC/EVA ratio and the vinyl acetate (VA) groups content (x) of EVA (i.e. EVAx). Physical-chemical properties of the resulting membranes are analyzed and correlated with their structure. The results of SEM analysis revealed miscible PVC/EVA70 blends (i.e. with 70 wt% of VA groups) and partially miscible PVC/EVA40 blends. The plasticizing effect of the EVA copolymer was confirmed by the tensile test results. The results of transport measurements showed that PIMs containing EVA40 and PVC are more efficient for the Cr(VI) extraction than those with only PVC. Thus, EVA40 can effectively replace the conventional liquid plasticizers while improving the Cr(VI) permeability. Besides, it is stated that EVA40-based PIMs are more stable as compared with conventional PIMs due to the water plasticizing effect. After the membrane optimization, the highest Cr(VI) transport flux (54.7 µmol·m-2·s-1) was measured. Moreover, the addition of 10 wt% of tetradecanol causes the increase of the water plasticizing effect and allows obtaining a PIM with high stability (up to 24 cycles) required for the membrane long-term operation.

Colloid formation and facilitated chromium transport in the coastal area soil induced by freshwater and seawater alternating fluctuations

Seawater seasonal fluctuation results in its close interaction with freshwater in the coastal area, which may affect behavior of contaminants there. This study was conducted to explore the transport and transformation of soil colloid and associated Cr during freshwater and seawater alternating fluctuations by laboratory experiment and numerical simulation. Such a fluctuation brought downward migration of Cr from upper contaminated soil and induced reduction of Cr(VI) into Cr(III). An obvious increase of retained Cr(III) was observed at the lower layers of soil due to the reducing environment. More importantly, the colloids with average sizes between 800-1500 nm was formed during the fluctuation and mainly composed of microcline and Fe/Mn oxides minerals, which determined the Cr transport. Compared with the previous freshwater fluctuation, seawater fluctuations generated more and larger–sized colloids due to its high ionic strength. These colloids carried over 94% Cr in the effluent and Cr(III) accounted for over 95% of total Cr. A colloid-facilitated Cr transport modeling showed that the soil retained Cr decreased by about 14% after eight rounds of fluctuation on an actual soil-contaminated site scale. Our study provides insight for the understanding of geochemical process of Cr in the coastal area under freshwater and seawater fluctuation conditions.

Binding and transport of Cr(III) by clay minerals during the Great Oxidation Event

A spike in chromium (Cr) abundance above crustal background in iron formations post-dating the Great Oxidation Event (ca. 2.5-2.3 billion years ago) has been suggested to reflect the evolution of terrestrial aerobic pyrite and siderite oxidation and the initiation of widespread acid rock drainage that would enhance Cr transport from terrestrial weathering environments to the oceans. However, it remains unclear whether Cr was transported in a soluble form (as Cr(III) or Cr(VI)), or bound to particulate surfaces. Here, we experimentally investigate the binding mechanisms of Cr(III) – the typical oxidation state associated with primary igneous minerals such as chromite – to three common soil clay minerals (kaolinite, illite, and montmorillonite) using extended X-ray adsorption fine structure (EXAFS) spectroscopy. Our results demonstrate that Cr(III) precipitates on the clay surfaces over a pH range of 6 to 8 as guyanaite (β-CrOOH) due to the replacement of surface Al-octahedra by paired Cr(III) octahedra. Bidentate bonding with a Cr-Cr interatomic distance of 3.43-3.51 Å indicates the incorporation of Cr(III) into the clay structure. A comparison between Cr(III) adsorption/precipitation onto the three clays and the desorption of Cr(III) from Cr(III)-spiked clays shows that kaolinite has the highest retention capacity for Cr(III), a predictable result given that an entire Al-octahedral sheet is exposed for Cr(III) binding, while illite and montmorillonite only have Al-edge sites. Moreover, Cr(III) was essentially immobilized in our experiments except under very acidic conditions (pH<2). Extending our results to the interpretation of the Cr record in iron formations, we suggest that under intense chemical weathering conditions, not only did acidity promote the solubilization of Cr(III) from primary Cr-bearing minerals, but that parent rocks were more systematically weathered to an advanced state dominated by kaolinite – creating ideal conditions for Cr adsorption. Erosion of regolith that scavenged mobilized Cr(III) could then facilitate transport of Cr(III)-bearing kaolinite to coastal environments where it contributed to the super-crustal Cr abundances above detrital background preserved in ca. 2.5-2.0 Ga iron formations.

Optimization of Cr(III) transport in a polymer inclusion membrane system through experimental design strategies

Optimization of Cr(III) transport in a polymer inclusion membrane system through experimental design strategies

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Study on formation of Pd nanocatalyst in self-reducing silica nanotube produced by using sacrificial Fe3O4 template and its efficacy in Cr(VI) reduction

Palladium is extensively used for catalyzing various organic and inorganic reactions. The nanostructures of Pd are expected to exhibit an improved catalytic efficacy. However, their uses have several issues which could be addressed by encapsulating the Pd nanostructures in the appropriate host matrices without affecting the accessibility of catalytic sites. In the present work, the silica nanotubes were formed by coating of the (3-glycidyloxypropyl)trimethoxysilane and tetraethoxysilane on the Fe3O4 NPs template, which was subsequently leached out. The reducing groups on the silica nanotubes were incorporated by the grafting of hydrazine using 3-glycidyloxypropyl linkers on the silica nanotubes and subsequently reacting with hydrazine. Thus formed silica nanotubes were loaded with the Pd NPs using self-reducing route and also using the external agent for further reduction of Pd2+ ions loaded by the ion-exchange mechanism, which increased the Pd loading from 43 mg g−1 to 128 mg g−1. Thus, formed Pd NPs loaded silica nanotubes were characterized by various techniques such as EDS, FESEM, HRTEM and SAXS to understand the formation of Pd NPs embedded silica nanotubes and their physical properties. The HRTEM images showed the formation of silica nanotubes having ≈10 nm diameter and varying length (20–60 nm). The SAXS studies suggested the Pd NPs were having 6 nm sizes irrespective of the reducing routes or the loading capacity. The Pd NPs loaded silica nanotubes were found to possess a remarkable efficiency for catalyzing the representative oxyions reduction of CrO42− to Cr(III) with formic acid at room temperature. Based on room temperature reduction, the transport of Cr(VI) across the anion-exchange membrane and subsequent reduction to Cr(III) in the receiver compartment was studied to develop a new Cr(VI)-separation process having the potentials applications for a variety of feeds.

Assessing the impact of lime on chromium migration in soil caused by basic chromium sulfate in tannery

ABSTRACT Chromium (Cr) pollution is the primary pollution problem of the soil in tannery. However, the effect of tanning chemicals on Cr migration in soil has not been clearly elucidated. Column leaching tests were designed in this study to reveal the transport and transformation of Cr from basic chromium sulfate (BCS) into soil and the effects of lime on Cr migration and transformation. The results showed that BCS was mainly leached out in the state of Cr(VI) after entering the soil, and the Cr concentration in leachate decreased with the increase of the bulking thickness of the BCS. Compared with the soil absent of lime, the concentration of total Cr in the leachate from soil with lime decreased by 8.80–88.1%. The proportions of Cr in the residual fraction were generally increased in the soil with lime, whereas other fractions were decreased. The presence of lime can reduce the migration and toxicity of BCS in soil to a certain extent. The analysis of soil bacterial community showed that the relative abundance of Proteobacteria increased significantly with the exposure to BCS and the Burkholderiaceae was the dominant bacteria family in the BCS contaminated soil. Understanding the mobility of BCS and lime and the bacterial community in BCS contaminated soil is conducive to the risk assessment of the tannery site.

Potential Biopolymer Adsorbent Functionalized with Fe3O4 Nanoparticles for the Removal of Cr(VI) From Aqueous Solution

In the present study, an adsorbent with a synergistic effect was developed from chitosan (CS) and Fe3O4 nanoparticles (Fe3O4 Nps) to remove Cr(VI) from aqueous solutions. The Fe3O4 Nps were synthesized by co-precipitation and were characterized by TEM. The CS/NPs composites were prepared by electrospinning technique and analyzed by SEM, FT-IR, DSC, and TGA. In the batch system, the influence of Fe3O4 Nps content, pH, contact time, Cr(VI) initial concentration, adsorbent dosage, and the temperature was investigated; the Cr(VI) concentration was determined using a colorimetric method by UV–Vis spectroscopy. The Fe3O4 Nps presented a quasi-spherical shape and an average size of 18 nm, with a low particle distribution. The SEM analysis reveals the presence of highly porous, interconnected micrometric structures. The optimal adsorption conditions were 1% load of Fe3O4 Nps by weight of CS, pH 3, 25 °C, and equilibrium was reached at just 9 min. Besides, the adsorption is favored by increasing Cr(VI) initial concentration and adsorbent dosage. The studies of reaction kinetics and adsorption equilibrium showed that the experimental data were better fitted to the Pseudo-second-order and Langmuir isotherm models, establishing monolayer formation and chemisorption. The maximum adsorption capacity of CS/Fe3O4 Nps was 440.75 mg/g, which indicates a high affinity of the adsorbent for Cr(VI). Finally, a kinetic diffusion study established that intraparticle diffusion, and in particular surface diffusion, are important resistances in the transport of Cr(VI) from the liquid phase to the active site.

Modeling and visualizing the transport and retention of cationic and oxyanionic metals (Cd and Cr) in saturated soil under various hydrochemical and hydrodynamic conditions

Cationic and oxyanionic metals are widely existed in the aquatic and soil environment with the process of industrialization and they may behave different transport properties in aquifer systems due to the opposite charges. In this study, the comparative transport behaviors of Cd2+ and CrO42− in water-saturated soil columns were investigated under a variety of hydrochemical and hydraulic conditions such as pH, ionic strength (IS), and flow rate. The transport mechanisms of Cd(II) and Cr(VI) were explored by fitting the breakthrough curves with a two-site non-equilibrium transport model. Results indicated that high solution pH inhibited the transport of Cd(II) due to the enhanced electrostatic interaction. In contrast, the migration of Cr(VI) was promoted with the least amount of Cr(VI) (1.23 mg) being retained in soil at high pH, ascribing to the stronger electrostatic repulsion between anions and soil surface. Meanwhile, high pH conditions were not favorable for the participation of reduced iron in the reduction process of Cr(VI), resulting in the least amount of Cr(III) detected (22%). The increase in ionic strength decreased the negativity of the potential at the adsorption plane, which enhanced the transport of cationic Cd(II) and the retardation of anionic Cr(VI). In addition, the increase in flow rate facilitated the transport of Cd(II) and Cr(VI), mainly due to the decreasing contacting with porous media and enhanced dispersion effect. These findings demonstrated that the fate and environmental behavior of metal cations and anions differed with the change of hydrochemical and hydrodynamic properties, which should be considered for the risk assessment and remediation of metal contaminated sites.

Turning AGN Bubbles into Radio Relics with Sloshing: Modeling CR Transport with Realistic Physics

Radio relics are arc-like synchrotron sources at the periphery of galaxy clusters, produced by cosmic-ray electrons in a μG magnetic field, which are believed to have been (re-)accelerated by merger shock fronts. However, not all relics appear at the same location as shocks as seen in the X-ray. In a previous work, we suggested that the shape of some relics may result from the pre-existing spatial distribution of cosmic-ray electrons, and tested this hypothesis using simulations by launching AGN jets into a cluster atmosphere with sloshing gas motions generated by a previous merger event. We showed that these motions could transport the cosmic ray-enriched material of the AGN bubbles to large radii and stretch it in a tangential direction, producing a filamentary shape resembling a radio relic. In this work, we improve our physical description for the cosmic rays by modeling them as a separate fluid which undergoes diffusion and Alfvén losses. We find that, including this additional cosmic ray physics significantly diminishes the appearance of these filamentary features, showing that our original hypothesis is sensitive to the modeling of cosmic ray physics in the intracluster medium.

Comparing different closure relations for cosmic ray hydrodynamics

ABSTRACT Cosmic ray (CR) hydrodynamics is a (re-)emerging field of high interest due to the importance of CRs for the dynamical evolution of the interstellar, the circumgalactic, and the intracluster medium. In these environments, CRs with GeV energies can influence large-scale dynamics by regulating star formation, driving galactic winds, or altering the pressure balance of galactic haloes. Recent efforts have moved the focus of the community from a one-moment description of CR transport towards a two-moment model as this allows for a more accurate description of the microphysics impacting the CR population. Like all hydrodynamical theories, these two-moment methods require a closure relation for a consistent and closed set of evolution equations. The goal of this paper is to quantify the impact of different closure relations on the resulting solutions. To this end, we review the common P1 and M1 closure relations, derive a new four-moment H1 description for CR transport, and describe how to incorporate CR scattering by Alfvén waves into these three hydrodynamical models. While there are significant differences in the transport properties of radiation in the P1 and M1 approximations in comparison to more accurate radiative transfer simulations using the discrete ordinates approximation, we only find small differences between the three hydrodynamical CR transport models in the free-streaming limit when we neglect CR scattering. Most importantly, for realistic applications in the interstellar, circumgalactic, or intracluster medium where CR scattering is frequent, these differences vanish and all presented hydrodynamical models produce the same results.

Kinetıc analysıs of Cr(VI) transport wıth electromembrane processes

AbstractBACKGROUNDIn this study, the transport of Cr (VI) ions was investigated with electroanalytical approach, called electro‐membrane extraction (EME), by using a supported liquid membrane (SLM).RESULTSAliquat 336 and Celgrad 2500 were used as a carrier and support material, respectively. Chromium (VI) ions were transferred from sample solution containing target analyte to extractant solution at low potential values (10–50 V) and with different current values (0.1–0.4 A).CONCLUSIONThe following parameters such as carrier change, carrier concentration effects, solvent change effect were investigated and Cr(VI) transport was achieved with 54.73% recovery in 100 min at optimum conditions. In the EME‐SLM process, Danesi mass transfer model was used to calculate the kinetic data, rate constant, flux, permeability, and recovery, for each parameter examined. © 2021 Society of Chemical Industry (SCI).

A Study on Reduction and Transport of Cr(VI) in Two-dimensional Soils with Root Systems

A Study on Reduction and Transport of Cr(VI) in Two-dimensional Soils with Root Systems

MHD-PIC Simulations of Cosmic-Ray Scattering and Transport in Inhomogeneously Ionized Plasma

Abstract Cosmic rays (CRs) have critical impacts in the multiphase interstellar medium (ISM), driving dynamical motions in low-density plasma and modifying the ionization state, temperature, and chemical composition of higher-density atomic and molecular gas. We present a study of CR propagation in inhomogeneously ionized plasma, addressing CR transport issues that arise in the cloudy ISM. Using one-dimensional magnetohydrodynamic (MHD) particle-in-cell simulations that include ion–neutral drag to damp Alfvén waves in a portion of the simulation domain, we self-consistently evolve the kinetic physics of CRs and background gas MHD. By introducing a damping region in our periodic domain, our simulations break translational symmetry and allow the emergence of spatial gradients in the CR distribution function. A spatial gradient opposite to the CR flux forms across the fully ionized region as a result of pitch angle scattering. We connect our results with CR hydrodynamics formulations by computing the wave–particle scattering rates as predicted by quasilinear, fluid, and Fokker–Planck theory. For momenta where the mean free path is short relative to the box size, we find excellent agreement among all scattering rates. However, we also find evidence of a reduced scattering rate for less energetic particles that are subject to the μ = 0 barrier in our simulations. Our work provides a first-principles verification of CR hydrodynamics when particles stream down their pressure gradient and opens a pathway toward comprehensive calibrations of transport coefficients from self-generated Alfvén wave scattering with CRs.

Nanoscale Zero-Valent Iron Modified by Bentonite with Enhanced Cr(VI) Removal Efficiency, Improved Mobility, and Reduced Toxicity.

The aggregation of nanoscale zero-valent iron (nZVI) particles and their limited transport ability in environmental media hinder their application in environmental remediation. In this study, the Cr(VI) removal efficiency, transport performance, and toxicity of nZVI and bentonite-modified nZVI (B-nZVI) were investigated. Compared with nZVI, B-nZVI improved the removal efficiency of Cr(VI) by 10%, and also significantly increased the transport in quartz sand and soil. Increasing the flow rate can enhance the transport of nZVI and B-nZVI in the quartz sand columns. The transport of the two materials in different soils was negatively correlated with the clay composition. Besides, modification of nZVI by bentonite could reduce toxicity to luminous bacteria (Photobacterium phosphereum T3) and ryegrass (Lolium perenne L.). Compared with Fe-EDTA, the transfer factors of nZVI and B-nZVI were 65.0% and 66.4% lower, respectively. This indicated that although iron nanoparticles accumulated in the roots of ryegrass, they were difficult to be transported to the shoots. The results of this study indicate that B-nZVI has a strong application potential in in situ environmental remediation.