Linkage of iron elution and dissolved oxygen consumption with removal of organic pollutants by nanoscale zero-valent iron: Effects of pH on iron dissolution and formation of iron oxide/hydroxide layer.

PubMed

Fujioka, Nanae; Suzuki, Moe; Kurosu, Shunji; Kawase, Yoshinori

2016-02-01

The iron elution and dissolved oxygen (DO) consumption in organic pollutant removal by nanoscale zero-valent iron (nZVI) was examined in the range of solution pH from 3.0 to 9.0. Their behaviors were linked with the removal of organic pollutant through the dissolution of iron and the formation of iron oxide/hydroxide layer affected strongly by solution pH and DO. As an example of organic pollutants, azo-dye Orange II was chosen in this study. The chemical composition analyses before and after reaction confirmed the corrosion of nZVI into ions, the formation of iron oxide/hydroxide layer on nZVI surface and the adsorption of the pollutant and its intermediates. The complete decolorization of Orange II with nZVI was accomplished very quickly. On the other hand, the total organic carbon (TOC) removal was considerably slow and the maximum TOC removal was around 40% obtained at pH 9.0. The reductive cleavage of azo-bond by emitted electrons more readily took place as compared with the cleavage of aromatic rings of Orange II leading to the degradation to smaller molecules and subsequently the mineralization. A reaction kinetic model based on the Langmuir-Hinshelwood/Eley-Rideal approach was developed to elucidate mechanisms for organic pollutant removal controlled by the formation of iron oxide/hydroxide layer, the progress of which could be characterized by considering the dynamic concentration changes in Fe(2+) and DO. The dynamic profiles of Orange II removal linked with Fe(2+) and DO could be reasonably simulated in the range of pH from 3.0 to 9.0. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nano-iron Tracer Test for Characterizing Preferential Flow Path in Fractured Rock

NASA Astrophysics Data System (ADS)

Chia, Y.; Chuang, P. Y.

2015-12-01

Deterministic description of the discrete features interpreted from site characterization is desirable for developing a discrete fracture network conceptual model. It is often difficult, however, to delineate preferential flow path through a network of discrete fractures in the field. A preliminary cross-borehole nano-iron tracer test was conducted to characterize the preferential flow path in fractured shale bedrock at a hydrogeological research station. Prior to the test, heat-pulse flowmeter measurements were performed to detect permeable fracture zones at both the injection well and the observation well. While a few fracture zones are found permeable, most are not really permeable. Chemical reduction method was used to synthesize nano zero-valent iron particles with a diameter of 50~150 nm. The conductivity of nano-iron solution is about 3100 μs/cm. The recorded fluid conductivity shows the arrival of nano-iron solution in the observation well 11.5 minutes after it was released from the injection well. The magnetism of zero-valent iron enables it to be absorbed on magnet array designed to locate the depth of incoming tracer. We found nearly all of absorbed iron on the magnet array in the observation well were distributed near the most permeable fracture zone. The test results revealed a preferential flow path through a permeable fracture zone between the injection well and the observation well. The estimated hydraulic conductivity of the connected fracture is 2.2 × 10-3 m/s. This preliminary study indicated that nano-iron tracer test has the potential to characterize preferential flow path in fractured rock.

Impact of carbon, oxygen and sulfur content of microscale zerovalent iron particles on its reactivity towards chlorinated aliphatic hydrocarbons.

PubMed

Velimirovic, Milica; Larsson, Per-Olof; Simons, Queenie; Bastiaens, Leen

2013-11-01

Zerovalent iron (ZVI) abiotically degrades several chlorinated aliphatic hydrocarbons (CAHs) via reductive dechlorination, which offers perspectives for in situ groundwater remediation applications. The difference in reactivity between ZVI particles is often linked with their specific surface area. However, other parameters may influence the reactivity as well. Earlier, we reported for a set of microscale zerovalent iron (mZVI) particles the disappearance kinetic of different CAHs which were collected under consistent experimental conditions. In the present study, these kinetic data were correlated with the carbon, oxygen and sulfur content of mZVI particles. It was confirmed that not only the specific surface area affects the disappearance kinetic of CAHs, but also the chemical composition of the mZVI particles. The chemical composition, in addition, influences CAHs removal mechanism inducing sorption onto mZVI particles instead of dechlorination. Generally, high disappearance kinetic of CAHs was observed for particles containing less oxygen. A high carbon content, on the other hand, induced nonreactive sorption of the contaminants on the mZVI particles. To obtain efficient remediation of CAHs by mZVI particles, this study suggested that the carbon and oxygen content should not exceed 0.5% and 1% respectively. Finally, the efficiency of the mZVI particles may be improved to some extent by enriching them with sulfur. However, the impact of sulfur content on the reactivity of mZVI particles is less pronounced than that of the carbon and oxygen content. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fate and Transport of Nanoparticles in Porous Media: A Numerical Study

NASA Astrophysics Data System (ADS)

Taghavy, Amir

Understanding the transport characteristics of NPs in natural soil systems is essential to revealing their potential impact on the food chain and groundwater. In addition, many nanotechnology-based remedial measures require effective transport of NPs through soil, which necessitates accurate understanding of their transport and retention behavior. Based upon the conceptual knowledge of environmental behavior of NPs, mathematical models can be developed to represent the coupling of processes that govern the fate of NPs in subsurface, serving as effective tools for risk assessment and/or design of remedial strategies. This work presents an innovative hybrid Eulerian-Lagrangian modeling technique for simulating the simultaneous reactive transport of nanoparticles (NPs) and dissolved constituents in porous media. Governing mechanisms considered in the conceptual model include particle-soil grain, particle-particle, particle-dissolved constituents, and particle- oil/water interface interactions. The main advantage of this technique, compared to conventional Eulerian models, lies in its ability to address non-uniformity in physicochemical particle characteristics. The developed numerical simulator was applied to investigate the fate and transport of NPs in a number of practical problems relevant to the subsurface environment. These problems included: (1) reductive dechlorination of chlorinated solvents by zero-valent iron nanoparticles (nZVI) in dense non-aqueous phase liquid (DNAPL) source zones; (2) reactive transport of dissolving silver nanoparticles (nAg) and the dissolved silver ions; (3) particle-particle interactions and their effects on the particle-soil grain interactions; and (4) influence of particle-oil/water interface interactions on NP transport in porous media.

Modeling coupled nanoparticle aggregation and transport in porous media: A Lagrangian approach

NASA Astrophysics Data System (ADS)

Taghavy, Amir; Pennell, Kurt D.; Abriola, Linda M.

2015-01-01

Changes in nanoparticle size and shape due to particle-particle interactions (i.e., aggregation or agglomeration) may significantly alter particle mobility and retention in porous media. To date, however, few modeling studies have considered the coupling of transport and particle aggregation processes. The majority of particle transport models employ an Eulerian modeling framework and are, consequently, limited in the types of collisions and aggregate sizes that can be considered. In this work, a more general Lagrangian modeling framework is developed and implemented to explore coupled nanoparticle aggregation and transport processes. The model was verified through comparison of model simulations to published results of an experimental and Eulerian modeling study (Raychoudhury et al., 2012) of carboxymethyl cellulose (CMC)-modified nano-sized zero-valent iron particle (nZVI) transport and retention in water-saturated sand columns. A model sensitivity analysis reveals the influence of influent particle concentration (ca. 70 to 700 mg/L), primary particle size (10-100 nm) and pore water velocity (ca. 1-6 m/day) on particle-particle, and, consequently, particle-collector interactions. Model simulations demonstrate that, when environmental conditions promote particle-particle interactions, neglecting aggregation effects can lead to under- or over-estimation of nanoparticle mobility. Results also suggest that the extent to which higher order particle-particle collisions influence aggregation kinetics will increase with the fraction of primary particles. This work demonstrates the potential importance of time-dependent aggregation processes on nanoparticle mobility and provides a numerical model capable of capturing/describing these interactions in water-saturated porous media.

Modeling coupled nanoparticle aggregation and transport in porous media: a Lagrangian approach.

PubMed

Taghavy, Amir; Pennell, Kurt D; Abriola, Linda M

2015-01-01

Changes in nanoparticle size and shape due to particle-particle interactions (i.e., aggregation or agglomeration) may significantly alter particle mobility and retention in porous media. To date, however, few modeling studies have considered the coupling of transport and particle aggregation processes. The majority of particle transport models employ an Eulerian modeling framework and are, consequently, limited in the types of collisions and aggregate sizes that can be considered. In this work, a more general Lagrangian modeling framework is developed and implemented to explore coupled nanoparticle aggregation and transport processes. The model was verified through comparison of model simulations to published results of an experimental and Eulerian modeling study (Raychoudhury et al., 2012) of carboxymethyl cellulose (CMC)-modified nano-sized zero-valent iron particle (nZVI) transport and retention in water-saturated sand columns. A model sensitivity analysis reveals the influence of influent particle concentration (ca. 70 to 700 mg/L), primary particle size (10-100 nm) and pore water velocity (ca. 1-6 m/day) on particle-particle, and, consequently, particle-collector interactions. Model simulations demonstrate that, when environmental conditions promote particle-particle interactions, neglecting aggregation effects can lead to under- or over-estimation of nanoparticle mobility. Results also suggest that the extent to which higher order particle-particle collisions influence aggregation kinetics will increase with the fraction of primary particles. This work demonstrates the potential importance of time-dependent aggregation processes on nanoparticle mobility and provides a numerical model capable of capturing/describing these interactions in water-saturated porous media. Copyright © 2014 Elsevier B.V. All rights reserved.

Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes.

PubMed

Bokare, Alok D; Choi, Wonyong

2014-06-30

Iron-catalyzed hydrogen peroxide decomposition for in situ generation of hydroxyl radicals (HO(•)) has been extensively developed as advanced oxidation processes (AOPs) for environmental applications. A variety of catalytic iron species constituting metal salts (in Fe(2+) or Fe(3+) form), metal oxides (e.g., Fe2O3, Fe3O4), and zero-valent metal (Fe(0)) have been exploited for chemical (classical Fenton), photochemical (photo-Fenton) and electrochemical (electro-Fenton) degradation pathways. However, the requirement of strict acidic conditions to prevent iron precipitation still remains the bottleneck for iron-based AOPs. In this article, we present a thorough review of alternative non-iron Fenton catalysts and their reactivity towards hydrogen peroxide activation. Elements with multiple redox states (like chromium, cerium, copper, cobalt, manganese and ruthenium) all directly decompose H2O2 into HO(•) through conventional Fenton-like pathways. The in situ formation of H2O2 and decomposition into HO(•) can be also achieved using electron transfer mechanism in zero-valent aluminum/O2 system. Although these Fenton systems (except aluminum) work efficiently even at neutral pH, the H2O2 activation mechanism is very specific to the nature of the catalyst and critically depends on its composition. This review describes in detail the complex mechanisms and emphasizes on practical limitations influencing their environmental applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Activation of Persulfate by Nanosized Zero-Valent Iron (NZVI): Mechanisms and Transformation Products of NZVI.

PubMed

Kim, Cheolyong; Ahn, Jun-Young; Kim, Tae Yoo; Shin, Won Sik; Hwang, Inseong

2018-03-20

The mechanisms involved in the activation of persulfate by nanosized zero-valent iron (NZVI) were elucidated and the NZVI transformation products identified. Two distinct reaction stages, in terms of the kinetics and radical formation mechanism, were found when phenol was oxidized by the persulfate/NZVI system. In the initial stage, lasting 10 min, Fe 0 (s) was consumed rapidly and sulfate radicals were produced through activation by aqueous Fe 2+ . The second stage was governed by Fe catalyzed activation in the presence of aqueous Fe 3+ and iron (oxyhydr)oxides in the NZVI shells. The second stage was 3 orders of magnitude slower than the initial stage. An electron balance showed that the sulfate radical yield per mole of persulfate was more than two times higher in the persulfate/NZVI system than in the persulfate/Fe 2+ system. Radicals were believed to be produced more efficiently in the persulfate/NZVI system because aqueous Fe 2+ was supplied slowly, preventing sulfate radicals being scavenged by excess aqueous Fe 2+ . In the second stage, the multilayered shell conducted electrons, and magnetite in the shell provided electrons for the activation of persulfate. Iron speciation analysis (including X-ray absorption spectroscopy) results indicated that a shrinking core/growing shell model explained NZVI transformation during the persulfate/NZVI process.

A combined process of adsorption and Fenton-like oxidation for furfural removal using zero-valent iron residue.

PubMed

Li, Furong; Bao, Jianguo; Zhang, Tian C; Lei, Yutian

2015-01-01

In this study, the feasibility of using a combined adsorption and Fenton-like oxidation process (with zero-valent iron (ZVI) residue from heat wraps as an absorbent and catalyst) to remove furfural in the solution was evaluated. The influencing parameters (e.g. pH, H2O2 concentration, initial furfural concentration) and the reusability of ZVI residue (to replace the iron powder) were estimated. The ZVI residue was found to have much better adsorption effect on furfural at pH 2.0 compared with pH 6.7. For Fenton-like reaction alone with ZVI residue, the highest furfural removal of 97.5% was observed at the concentration of 0.176 mol/L H2O2, and all of the samples had >80% removal efficiency at different initial furfural concentrations of 2, 10, 20, 30 and 40 mmol/L. However, with a combined adsorption and Fenton-like oxidation, the removal efficiency of furfural was nearly 100% for all treatments. The ZVI residue used for furfural removal was much better than that of iron powder in the Fenton-like reaction at a seven-cycle experiment. This study suggests the combined process of adsorption and Fenton-like oxidation using ZVI residue is effective for the treatment of furfural in the liquid.

Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM).

PubMed

Liu, Airong; Zhang, Wei-xian

2014-09-21

An angstrom-resolution physical model of nanoscale zero-valent iron (nZVI) is generated with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) on the Fe L-edge. Bright-field (BF), high-angle annular dark-field (HAADF) and secondary electron (SE) imaging of nZVI acquired by a Hitachi HD-2700 STEM show near atomic resolution images and detailed morphological and structural information of nZVI. The STEM-EDS technique confirms that the fresh nZVI comprises of a metallic iron core encapsulated with a thin layer of iron oxides or oxyhydroxides. SAED patterns of the Fe core suggest the polycrystalline structure in the metallic core and amorphous nature of the oxide layer. Furthermore, Fe L-edge of EELS shows varied structural features from the innermost Fe core to the outer oxide shell. A qualitative analysis of the Fe L(2,3) edge fine structures reveals that the shell of nZVI consists of a mixed Fe(II)/Fe(III) phase close to the Fe (0) interface and a predominantly Fe(III) at the outer surface of nZVI.

DEMONSTRATION BULLETIN: METAL-ENHANCED ABIOTIC DEGRADATION TECHNOLOGY - ENVIROMETAL TECHNOLOGIES, INC.

EPA Science Inventory

EnviroMetal Technologies, Inc. (ETI), of Guelph, ON, Canada, has developed the metal-enhanced abiotic degradation technology to treat halogenated volatile organic compounds (VOC) in water. A reactive, zero-valent, granular iron medium causes reductive dehalogenation of VOCs yield...

ACCUMULATION RATE OF MICROBIAL BIOMASS AT TWO PERMEABLE REACTIVE BARRIER SITES

EPA Science Inventory

Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of in-situ Permeable Reactive Barriers for treating contaminated groundwater. Both processes can impact remedial performance by decreasing zero-valent iron reactivity...

PERMEABLE REACTIVE BARRIER STRATEGIES FOR REMEDIATION OF ARSENIC-CONTAMINATED GROUNDWATER

EPA Science Inventory

Results are presented from laboratory batch tests using zero-valent iron to treat arsenic-contaminated groundwater. The laboratory tests were conducted using near- neutral pH groundwater from a contaminated aquifer located adjacent to a custom smelting facility. Experiments we...

DECHLORINATION OF POLYCHLORINATED BIPHENYLS IN SEDIMENT SLURRIES BY PALLADIUM MODIFIED ZEROVALENT IRON

EPA Science Inventory

Polychlorinated biphenyls (PCBs) are one group of persistent organic pollutants (POPs) of international concern because of global distribution, persistence, and toxicity. Removal of these compounds from the environment presents a very tough challenge because they are highly hydro...

Transformation of Chlorinated Hydrocarbons on Synthetic Green Rusts

EPA Science Inventory

Green rusts (GRs) are layered double hydroxides that contain both ferrous and ferric ions in their structure. GRs can potentially serve as a chemical reductant for degradation of chlorinated hydrocarbons. GRs are found in zerovalent iron based permeable reactive barriers and in c...

Monothioarsenate Occurrence in Bangladesh Groundwater and Its Removal by Ferrous and Zero-Valent Iron Technologies.

PubMed

Planer-Friedrich, Britta; Schaller, Jörg; Wismeth, Fabian; Mehlhorn, Judith; Hug, Stephan J

2018-05-15

In most natural groundwaters, sulfide concentrations are low, and little attention has been paid to potential occurrence of thioarsenates (As V S n -II O 4- n 3- with n = 1-4). Thioarsenate occurrence in groundwater could be critical with regard to the efficiency of iron (Fe)-based treatment technologies because previous studies reported less sorption of thioarsenates to preformed Fe-minerals compared to arsenite and arsenate. We analyzed 273 groundwater samples taken from different wells in Bangladesh over 1 year and detected monothioarsenate (MTA), likely formed via solid-phase zero-valent sulfur, in almost 50% of all samples. Concentrations ranged up to >30 μg L -1 (21% of total As). MTA removal by locally used technologies in which zero-valent or ferrous Fe is oxidized by aeration and As sorbs or coprecipitates with the forming Fe(III)hydroxides was indeed lower than for arsenate. The presence of phosphate required up to three times as much Fe(II) for comparable MTA removal. However, in contrast to previous sorption studies on preformed Fe minerals, MTA removal, even in the presence of phosphate, was still higher than that of arsenite. The more efficient MTA removal is likely caused by a combination of coprecipitation and adsorption rendering the tested Fe-based treatment technologies suitable for As removal also in the presence of MTA.

Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater.

PubMed

Han, Weijiang; Fu, Fenglian; Cheng, Zihang; Tang, Bing; Wu, Shijiao

2016-01-25

The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+)) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

The removal of chromium (VI) and lead (II) from groundwater using sepiolite-supported nanoscale zero-valent iron (S-NZVI).

PubMed

Fu, Rongbing; Yang, Yingpin; Xu, Zhen; Zhang, Xian; Guo, Xiaopin; Bi, Dongsu

2015-11-01

In this study, the synthesis and characterization of sepiolite-supported nanoscale zero-valent iron particles (S-NZVI) was investigated for the adsorption/reduction of Cr(VI) and Pb(II) ions. Nanoscale zero-valent iron (NZVI) supported on sepiolite was successfully used to remove Cr(VI) and Pb(II) from groundwater with high efficiency. The removal mechanism was proposed as a two-step interaction including both the physical adsorption of Cr(VI) and Pb(II) on the surface or inner layers of the sepiolite-supported NZVI particles and the subsequent reduction of Cr(VI) to Cr(III) and Pb(II) to Pb(0) by NZVI. The immobilization of the NZVI particles on the surface of sepiolite could help to overcome the disadvantage of NZVI particles, which have strong tendency to agglomerate into larger particles, resulting in an adverse effect on both the effective surface area and reaction performance. The techniques of XRD, XPS, BET, Zeta potential, and TEM were used to characterize the S-NZVI and interaction between S-NZVI and heavy metals. The appropriate S-NZVI dosage was 1.6 g L(-1). The removal efficiency of Cr(VI) and Pb(II) by S-NZVI was not affected to any considerable extent by the presence of co-existing ions, such as H2PO4(-), SiO3(2-), Ca(2+) and HCO3(-). The Cr(VI) and Pb(II) removal kinetics followed a pseudo-first-order rate expression, and both Langmuir isotherm model and Freundlich isotherm model were proposed. The results suggested that supporting NZVI on sepiolite had the potential to become a promising technique for in situ heavy metal-contaminated groundwater remediation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transport of carbon colloid supported nanoscale zero-valent iron in saturated porous media

NASA Astrophysics Data System (ADS)

Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E.

2014-08-01

Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d50 = 2.4 μm) are investigated in column tests using columns of 40 cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5 mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from - 62 mV to - 80 mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions.

Structural Evolution of Nanoscale Zero-Valent Iron (nZVI) in Anoxic Co2+Soultion : Interactional Performance and Mechanism

NASA Astrophysics Data System (ADS)

Dai, C.; Zhang, Y.

2015-12-01

The nanoscale particle and low oxidation reduction potential make nano zero-valent iron (nZVI) an efficient sorbent and reductant for treating many kinds of organic contaminants and heavy metals.The structures of nanoscale zero-valent iron (nZVI) particles are evolving in reactions, and the reactions are influenced by the evolved structures. In order to understand the detail removal process, it is important to investigate the interactions between reactions and structural evolution. In this work, reactions between nZVI and Co2+ at different initial concentrations in anoxic aqueous solutions (to eliminate the effects of O2) were tracked for 10 days using a variety of methods including inductively coupled plasma optical emission spectrometry (ICP-OES), high resolution-transmission electron microscopy (HR-TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). Continuous removal and reduction of Co2+ by nZVI caused by structural evolution were revealed in reaction processes. The system pH (pH measured in mixture), which controls the stability of coprecipitation and the corrosion rate of nZVI, was deemed as the determining factors of structural evolutions. X-ray photoelectron spectroscopy (XPS) results showed that the formation and dissolution of sheet structure impacts on the ratio of Fe (0) on nZVI's surface and the surface reduction of Co2+. The cavity structure provides the possibility of Co migrating from surface to inside of nZVI leading a continuous removal. A subacidity condition could accelerate the evolution to improve the removal of Co2+ and the results of structural controlled reactions further indicated that the removal was suspended by sheet structure and enhanced by cavity structure. The results in this study revealed "structural influence" for fully and dynamically understanding nZVI's reactions.

Functional kaolin supported nanoscale zero-valent iron as a Fenton-like catalyst for the degradation of Direct Black G.

PubMed

Lin, Jiajiang; Sun, Mengqiang; Liu, Xinwen; Chen, Zuliang

2017-10-01

Kaolin supported nanoscale zero-valent iron (K-nZVI) is synthesized and applied as the Fenton-like oxidation catalyst to degrade a model azo dye, Direct Black G (DBG). The characterization of K-nZVI by the high resolution transmission electronmicroscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Energy Diffraction Spectrum (EDS) and X-ray diffraction (XRD) show that kaolin as a support material not only reduces the aggregation of zero-valent iron (nZVI) but also facilitates the Fenton-like oxidation by increasing the local concentration of DBG in the vicinity of nZVI. Pseudo first-order and pseudo second-order kinetic models are employed to reveal the adsorption and degradation of the DBG using K-nZVI as the catalyst. A better fit with pseudo second-order model for the adsorption process and equal excellent fits with pseudo first-order and pseudo second-order models for the degradation process are observed; the adsorption process is found to be the rate limiting step for overall reactions. The adsorption, evaluated by isotherms and thermodynamic parameters is a spontaneous and endothermic process. High-performance liquid chromatography-mass spectrometry (LC-MS) analysis was used to test degraded products in the degradation of DGB by K-nZVI. A removal mechanism based on the adsorption and degradation is proposed, including (i) prompt adsorption of DBG onto the K-nZVI surface, and (ii) oxidation of DBG by hydroxyl radicals at the K-nZVI surface. The application of K-nZVI to treat real wastewater containing azo dyes shows excellent degradation efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

Field demonstration of DNAPL dehalogenation using emulsified zero-valent iron

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Chris; Brooks, Kathleen; Coon, Christina; O'Hara, Suzanne; Krug, Thomas; Major, David; Yoon, Woong-Sang; Gavaskar, Arun;

Field Demonstration of DNAPL Dehalogenation Using Emulsified Zero-Valent Iron

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Chris; Brooks, Kathleen; Coon, Christina; O'Hara, Suzanne; Krug, Thomas; Major, David; Yoon, Sam; Gavaskar, Arun;

Transport of carbon colloid supported nanoscale zero-valent iron in saturated porous media.

PubMed

Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E

2014-08-01

Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d50=2.4μm) are investigated in column tests using columns of 40cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from -62mV to -80mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of activated carbon fiber supported nanoscale zero-valent iron for chromium (VI) removal from groundwater in a permeable reactive column.

PubMed

Qu, Guangzhou; Kou, Liqing; Wang, Tiecheng; Liang, Dongli; Hu, Shibin

2017-10-01

An activated carbon fiber supported nanoscale zero-valent iron (ACF-nZVI) composite for Cr(VI) removal from groundwater was synthesized according to the liquid phase reduction method. The techniques of N 2 adsorption/desorption, FESEM, EDX, XRD and XPS were used to characterize the ACF-nZVI composite and the interaction between the ACF-nZVI composite and Cr(VI) ions. Batch experiments were conducted to evaluate the effects of several factors, including the amount of nZVI on activated carbon fiber (ACF), pH value, initial Cr(VI) concentration, and co-existing ions on Cr(VI) removal. The results indicate that presence of ACF can inhibit the aggregation of nanoscale zero-valent iron (nZVI) particles and increase its reactivity, and the Cr(VI) removal efficiency increases with increasing amounts of nZVI on ACF and a decrease in the initial Cr(VI) concentration. In acidic conditions, almost 100% of Cr(VI) in solution can be removed after 60 min of reaction, and the removal efficiency decreases with increasing initial pH values. The Cr(VI) removal is also dependent on the co-existing ions. Reusability experiments on ACF-nZVI demonstrate that the ACF-nZVI composite can keep a high reactivity after five successive reduction cycles. The removal mechanisms are proposed as a two-step interaction including the physical adsorption of Cr(VI) on the surface or inner layers of the ACF-nZVI composite and the subsequent reduction of Cr(VI) to Cr(III) by nZVI. Copyright © 2017 Elsevier Ltd. All rights reserved.

Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas

DTIC Science & Technology

2010-04-01

The EZVI is composed of food-grade surfactant, biodegradable oil , water, and ZVI particles (either nano- or micro-scale iron), which form...emulsion particles (Figure 2-1). Each emulsion particle or droplet contains ZVI particles in water surrounded by an oil -liquid membrane. Since the...exterior oil membrane of the emulsion droplet has hydrophobic properties similar to that of DNAPL, the droplets are miscible with DNAPL. It is believed

Preparation of nanoscale iron (oxide, oxyhydroxides and zero-valent) particles derived from blueberries: Reactivity, characterization and removal mechanism of arsenate.

PubMed

Manquián-Cerda, Karen; Cruces, Edgardo; Angélica Rubio, María; Reyes, Camila; Arancibia-Miranda, Nicolás

2017-11-01

The application of iron nanoparticles (FeNPs) to the removal of various pollutants has received wide attention over the last few decades. A synthesis alternative to obtain these nanoparticles without using harmful chemical reagents, such as NaBH 4 , is the use of extracts from different natural sources that allow a lesser degree of agglomeration, in a process known as green synthesis. In this study, FeNPs were synthesized by 'green' (hereafter, BB-Fe NPs) and 'chemical' (hereafter, nZVI) methods. Extracts of leaves and blueberry shoots (Vaccinium corymbosum) were used as reducing agents for FeCl 3 ·6H 2 O solution in the green synthesis method. FeNPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrophoretic migration, Brunauer-Emmett-Teller (BET) surface area analysis and X-ray diffraction (XRD) and evaluated for the removal of As(V) from aqueous systems. In both synthesis methods, XRD analysis confirmed the presence of the different kinds of iron nanoparticles. SEM analysis showed that the average size of BB-Fe NPs was 52.4nm and that a variety of nanoparticles of different forms and associated structures, such as lepidocrocite, magnetite, and nZVI, were present, while the dimensions of nZVI were 80.2nm. Comparatively significant differences regarding the electrophoretic mobility were found between both materials pre- and post-sorption of As(V). The velocity of As(V) removal by BB-Fe NPs was slower than that by nZVI, reaching equilibrium at 120min compared to 60min for nZVI. The removal kinetics of As(V) were adequately described by the pseudo-second-order kinetic model, and the maximum adsorbed amounts of this analyte are in close accordance with the experimental results. The Langmuir-Freundlich model is in good agreement with our experimental data, where the sorption capacity of nZVI and BB-Fe NPs was found to be 52.23 ± 6.06 and 50.40 ± 5.90 (mg·g -1 ), respectively. The use of leaves of Vaccinium corymbosum affords an easy-to-synthesize, low-cost, and eco-friendly material with capabilities similar to nZVI. BB-Fe NPs are promising for arsenic remediation, which has emerged as a new alternative for water purification and sanitation. Copyright © 2017 Elsevier Inc. All rights reserved.

FIELD STUDY OF ARSENIC REMOVAL FROM GROUNDWATER BY ZEROVALENT IRON

EPA Science Inventory

Contamination of ground-water resources by arsenic is a widespread environmental problem; consequently, there is a need for developments and improvements of remedial technologies to effectively manage arsenic contamination in ground water and soils. In June 2005, a 7 m long, 14 ...

ZERO-VALENT IRON PRB APPLICATION EXPANDS TO ARSENIC REMOVAL

EPA Science Inventory

The U.S. EPA Office of Research and Development’s National Risk Management Research Laboratory (NRMRL) and Region 8 have begun evaluating performance of a pilot-scale permeable reactive barrier (PRB) to treat arsenic-contaminated ground water at the ASARCO Superfund near Helena, ...

Demonstration of Combined Zero-Valent Iron and Electrical Resistance Heating for In Situ Trichloroethene Remediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Truex, Michael J.; Macbeth, Tamzen; Vermeul, Vincent R.

The effectiveness of in situ treatment using zero-valent iron to remediate sites with non-aqueous phase or significant sediment-associated contaminant mass can be limited by relatively low rates of mass transfer to bring contaminants in contact with the reactive media. For a field test in a trichloroethene source area, combining moderate-temperature (maximum 50oC) subsurface electrical resistance heating with in situ ZVI treatment was shown to accelerate dechlorination and dissolution rates by a factor of 4 to 6 based on organic daughter products and a factor 8-16 using a chloride concentrations. A mass-discharge-based analysis was used to evaluate reaction, dissolution, and volatilizationmore » at ambient groundwater temperature (~10oC) and as temperature was increased up to about 50oC. Increased reaction and contaminant dissolution were observed with increased temperature, but volatilization was minimal during the test because in situ reactions maintained low aqueous-phase TCE concentrations.« less

Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes.

PubMed

Singh, Ritu; Misra, Virendra; Singh, Rana Pratap

2012-02-01

The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI).

Improving dewaterability of waste activated sludge by combined conditioning with zero-valent iron and hydrogen peroxide.

PubMed

Zhou, Xu; Wang, Qilin; Jiang, Guangming; Zhang, Xiwang; Yuan, Zhiguo

2014-12-01

Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel method based on combined conditioning with zero-valent iron (ZVI) and hydrogen peroxide (HP) at pH 2.0 to improve dewaterability of a full-scale waste activated sludge (WAS). The combination of ZVI (0-750mg/L) and HP (0-750mg/L) at pH 2.0 substantially improved the WAS dewaterability due to Fenton-like reactions. The highest improvement in WAS dewaterability was attained at 500mg ZVI/L and 250mg HP/L, when the capillary suction time of the WAS was reduced by approximately 50%. Particle size distribution indicated that the sludge flocs were decomposed after conditioning. Economic analysis showed that combined conditioning with ZVI and HP was a more economically favorable method for improving WAS dewaterability than the classical Fenton reaction based method initiated by ferrous salts and HP. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhancing dewaterability of waste activated sludge by combined oxidative conditioning process with zero-valent iron and peroxymonosulfate.

PubMed

Zhou, Xu; Jin, Wenbiao; Chen, Hongyi; Chen, Chuan; Han, Songfang; Tu, Renjie; Wei, Wei; Gao, Shu-Hong; Xie, Guo-Jun; Wang, Qilin

2017-11-01

The enhancement of sludge dewaterability is of great importance for facilitating the sludge disposal during the operation of wastewater treatment plants. In this study, a novel oxidative conditioning approach was applied to enhance the dewaterability of waste activated sludge by the combination of zero-valent iron (ZVI) and peroxymonosulfate (PMS). It was found that the dewaterability of sludge was significantly improved after the addition of ZVI (0-4 g/g TSS) (TSS: total suspended solids) and PMS (0-1 g/g TSS). The optimal addition amount of ZVI and PMS was 0.25 g/g TSS and 0.1 g/g TSS, respectively, under which the capillary suction time of the sludge was reduced by approximately 50%. The decomposition of sludge flocs could contribute to the improved sludge dewaterability. Economic analysis demonstrated that the proposed conditioning process with ZVI and PMS was more economical than the ZVI + peroxydisulfate and the traditional Fenton conditioning processes.

Micro-electrolysis of Cr (VI) in the nanoscale zero-valent iron loaded activated carbon.

PubMed

Wu, Limei; Liao, Libing; Lv, Guocheng; Qin, Faxiang; He, Yujuan; Wang, Xiaoyu

2013-06-15

In this paper we prepared a novel material of activated carbon/nanoscale zero-valent iron (C-Fe(0)) composite. The C-Fe(0) was proved to possess large specific surface area and outstanding reducibility that result in the rapid and stable reaction with Cr (VI). The prepared composite has been examined in detail in terms of the influence of solution pH, concentration and reaction time in the Cr (VI) removal experiments. The results showed that the C-Fe(0) formed a micro-electrolysis which dominated the reaction rate. The Micro-electrolysis reaches equilibrium is ten minutes. Its reaction rate is ten times higher than that of traditional adsorption reaction, and the removal rate of Cr reaches up to 99.5%. By analyzing the obtained profiles from the cyclic voltammetry, PXRD and XPS, we demonstrate that the Cr (VI) is reduced to insoluble Cr (III) compound in the reaction. Copyright © 2013 Elsevier B.V. All rights reserved.

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene.

PubMed

Yan, Jingchun; Han, Lu; Gao, Weiguo; Xue, Song; Chen, Mengfang

2015-01-01

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reduction of aqueous CrVI using nanoscale zero-valent iron dispersed by high energy electron beam irradiation.

PubMed

Zhang, Jing; Zhang, Guilong; Wang, Min; Zheng, Kang; Cai, Dongqing; Wu, Zhengyan

2013-10-21

High energy electron beam (HEEB) irradiation was used to disperse nanoscale zero-valent iron (NZVI) for reduction of CrVI to CrIII in aqueous solution. Pore size distribution, scanning electron microscopy and X-ray diffraction characterizations demonstrated that HEEB irradiation could effectively increase the dispersion of NZVI resulting in more active reduction sites of Crvi on NZVI. Batch reduction experiments indicated that the reductive capacity of HEEB irradiation-modified NZVI (IMNZVI) was significantly improved, as the reductive efficiency reached 99.79% under the optimal conditions (electron beam dose of 30 kGy at 10 MeV, pH 2.0 and 313 K) compared with that of raw NZVI (72.14%). Additionally, the NZVI was stable for at least two months after irradiation. The modification mechanism of NZVI by HEEB irradiation was investigated and the results indicated that charge and thermal effects might play key roles in dispersing the NZVI particles.

Removal of selenite by zero-valent iron combined with ultrasound: Se(IV) concentration changes, Se(VI) generation, and reaction mechanism.

PubMed

Fu, Fenglian; Lu, Jianwei; Cheng, Zihang; Tang, Bing

2016-03-01

In this paper, the performance and application of zero-valent iron (ZVI) assisted by ultrasonic irradiation for the removal of selenite (Se(IV)) in wastewater was evaluated and reaction mechanism of Se(IV) with ZVI in such systems was investigated. A series of batch experiments were conducted to determine the effects of ultrasound power, pH, ZVI concentration, N2 and air on Se(IV) removal. ZVI before and after reaction with Se(IV) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ultrasound can lead to a significant synergy in the removal of Se(IV) by ZVI because ultrasound can promote the generation of OH and accelerate the advanced Fenton process. The primary reaction products of ZVI and Se(IV) were Se(0), ferrihydrite, and Fe2O3. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation of 4-Chloro-3,5-Dimethylphenol by a Heterogeneous Fenton-Like Reaction Using Nanoscale Zero-Valent Iron Catalysts

PubMed Central

Xu, Lejin; Wang, Jianlong

2013-01-01

Abstract Degradation of 4-chloro-3,5-dimethylphenol (PCMX) by a heterogeneous Fenton-like process using nanoparticulate zero-valent iron (nZVI) and hydrogen peroxide (H2O2) at pH 6.3 was investigated. Interactive effects of three factors—initial PCMX concentration, nZVI dosage, and H2O2 concentration—were investigated using the response surface method based on the Box–Behnken design. Experimental results showed that complete decomposition of PCMX and 65% of total organic carbon removal were observed after 30 min of reaction at neutral pH under recommended reaction conditions: nZVI, 1.0 g/L; H2O2, 18 mM; and initial PCMX concentration, 0.15 g/L. Based on the effects of scavengers n-butanol and KI, removal of PCMX was mainly attributed to the attack of •OH, especially the surface-bonded •OH. A possible degradation pathway of PCMX was proposed. PMID:23781127

Removal of polybrominated diphenyl ethers by biomass carbon-supported nanoscale zerovalent iron particles: influencing factors, kinetics, and mechanism.

PubMed

Fu, Rongbing; Xu, Zhen; Peng, Lin; Bi, Dongsu

2016-12-01

In this study, nanoscale zerovalent iron (NZVI) immobilized on biomass carbon was used for the high efficient removal of BDE 209. NZVI supported on biomass carbon minimized the aggregation of NZVI particles resulting in the increased reaction performance. The proposed removal mechanism included the adsorption of BDE 209 on the surface or interior of the biomass carbon NZVI (BC-NZVI) particles and the subsequent debromination of BDE 209 by NZVI while biomass carbon served as an electron shuttle. BC-NZVI particles and the interaction between BC-NZVI particles and BDE 209 were characterized by TEM, XRD, and XPS. The removal reaction followed a pseudo-first-order rate expression under different reaction conditions, and the k obs was higher than that of other NZVI-supported materials. The debromination of BDE 209 by BC-NZVI was a stepwise process from nona-BDE to DE. A proposed pathway suggested that supporting NZVI on biomass carbon has potential as a promising technique for in situ organic-contaminated groundwater remediation.

Assessment of the use of sorbent amendments for reduction of mercury methylation in wetland sediments at Acadia National Park, Maine

USGS Publications Warehouse

Huntington, Thomas G.; Lewis, Ariel; Amirbahman, Aria; Marvin-DiPasquale, Mark C.; Culbertson, Charles W.

2015-01-01

The results of field mesocosm experiments indicated that there was a decreasing trend in pore-water methylmercury concentration after application of granular activated carbon but methylation was not affected because there was no corresponding decrease in sediment methylmercury concentration. The application of granular activated carbon resulted in the sorption of methylmercury. The application of granular activated carbon resulted in an increase in the distribution coefficient for methylmercury indicating that this amendment caused a higher proportion of methylmercury to be associated with the sediment than the pore water in comparison to the reference (untreated) condition. Experiments to test whether zero-valent iron or granular activated carbon would reduce the biouptake of methylmercury in snails were inconsistent; zero-valent iron had no effect on uptake in one experiment but resulted in a significant decrease in uptake in a second experiment. Granular activated carbon did not affect biouptake in either experiment.

Chemical removal of nitrate from water by aluminum-iron alloys.

PubMed

Xu, Jie; Pu, Yuan; Qi, Wei-Kang; Yang, Xiao Jin; Tang, Yang; Wan, Pingyu; Fisher, Adrian

2017-01-01

Zero-valent iron has been intensively investigated in chemical reduction of nitrate in water, but the reduction requires acidic or weak acidic pH conditions and the product of the reduction is exclusively ammonium, an even more toxic substance. Zero-valent aluminum is a stronger reductant than iron, but its use for the reduction of aqueous nitrate requires considerably alkaline pH conditions. In this study, aluminum-iron alloys with an iron content of 10%, 20% and 58% (termed Al-Fe10, Al-Fe20 and Al-Fe58, respectively) were investigated for the reduction of aqueous nitrate. Al-Fe alloys were efficient to reduce nitrate in water in an entire pH range of 2-12 and the reduction proceeded in a pseudo-first order at near neutral pH conditions. The observed reaction rate constant (K obs ) of Al-Fe10 was 3 times higher than that of Fe and the K obs of Al-Fe20 doubled that of Al-Fe10. The nitrogen selectivity of the reduction by Al-Fe10, Al-Fe20 and Al-Fe58 was 17.6%, 23.9% and 40.3%, respectively at pH 7 and the nitrogen selectivity by Al-Fe20 increased from 18.9% at pH 2-60.3% at pH 12. The enhanced selectivity and reactivity of Al-Fe alloys were likely due to the presence of an intermetallic Al-Fe compound (Al 13 Fe 4 ). Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanoscale zero-valent iron (nZVI): aspects of the core-shell structure and reactions with inorganic species in water.

PubMed

Yan, Weile; Herzing, Andrew A; Kiely, Christopher J; Zhang, Wei-Xian

2010-11-25

Aspects of the core-shell model of nanoscale zero-valent iron (nZVI) and their environmental implications were examined in this work. The structure and elemental distribution of nZVI were characterized by X-ray energy-dispersive spectroscopy (XEDS) with nanometer-scale spatial resolution in an aberration-corrected scanning transmission electron microscope (STEM). The analysis provides unequivocal evidence of a layered structure of nZVI consisting of a metallic iron core encapsulated by a thin amorphous oxide shell. Three aqueous environmental contaminants, namely Hg(II), Zn(II) and hydrogen sulfide, were studied to probe the reactive properties and the surface chemistry of nZVI. High-resolution X-ray photoelectron spectroscopy (HR-XPS) analysis of the reacted particles indicated that Hg(II) was sequestrated via chemical reduction to elemental mercury. On the other hand, Zn(II) removal was achieved via sorption to the iron oxide shell followed by zinc hydroxide precipitation. Hydrogen sulfide was immobilized on the nZVI surface as disulfide (S(2)(2-)) and monosulfide (S(2-)) species. Their relative abundance in the final products suggests that the retention of hydrogen sulfide occurs via reactions with the oxide shell to form iron sulfide (FeS) and subsequent conversion to iron disulfide (FeS(2)). The results presented herein highlight the multiple reactive pathways permissible with nZVI owing to its two functional constituents. The core-shell structure imparts nZVI with manifold functional properties previously unexamined and grants the material with potentially new applications. Copyright © 2010 Elsevier B.V. All rights reserved.

Mitigation of Irrigation Water Using Zero-Valent Iron Treatment

USDA-ARS?s Scientific Manuscript database

Significant problems have occurred in the U.S. with regard to the contamination of produce by pathogenic bacteria. Minimally processed produce lacks the processing and preparation hurdles, such as cooking, to aid in reduction or elimination of the occasional and incidental contamination that can le...

EZVI Injection Field Test Leads to Pilot-Scale Application

EPA Science Inventory

Testing and monitoring of emulsified zero-valent ironTM (EZVI) injections was conducted at Cape Canaveral Air Force Station’s Launch Complex 34, FL, in 2002 to 2005 to evaluate the technology’s efficacy in enhancing in situ dehalogenation of dense nonaqueous-phase liquid (DNAPL) ...

MICROCOSM STUDY OF DEGRADATION OF CHLORINATED SOLVENTS ON SYNTHETIC GREEN RUST MINERALS

EPA Science Inventory

Green rust minerals contain ferrous ion in their structure that can potentially serve as a chemical reductant for degradation of chlorinated solvents. Green rusts are found in zerovalent iron based permeable reactive barriers and in certain soil and sediments. Some previous labor...

Preparation of novel composites based on hydrophilized and functionalized polyacrylonitrile membrane-immobilized NZVI for reductive transformation of metronidazole

NASA Astrophysics Data System (ADS)

Wang, Xiangyu; Liu, Peng; Ma, Jun; Liu, Huiling

2017-02-01

For the first time, hydrophilized and functionalized polyacrylonitrile (PAN) membrane was synthesized via two-stage process, addition of polyvinyl alcohol and in situ polymerization of acrylic acid (AA), and nano zero-valent iron (NZVI) was incorporated within modified membrane. The as-prepared PAA/PAN-NZVI (PPN) composites possessed superior reactivity for metronidazole (MNZ) with transformation ratio 2.03 and reaction rate 4.77 times higher than that by bare NZVI. Meanwhile, the enhanced stability and recyclability of PPN composites were maintained over repeated cycles. The major advantages of synthetic method lie in the remarkably increased loading and decreased agglomeration of NZVI. Moreover, with hydrophilized and functionalized synthesis processes of membrane, the potential risk of released iron ions was not a concern due to strong chelation of grafted carboxyl groups. Analyses of morphological characteristics (FE-SEM), chemical structure (FTIR), element valence and groups (XPS) of samples confirmed the successful graft of carboxylic acid groups and formation of a uniform iron nanoparticles coating onto PAN matrix. The reaction kinetics of MNZ with PPN composites were well-described by a two-parameter pseudo-first-order decay model with activation energy of 29.5 kJ/mol. The co-solutes except humic acid had a negligible effect on MNZ transformation. Determination of intermediates revealed that nitro reduction, N-denitration and hydroxyethyl cleavage were the main pathways for transformation of MNZ. The findings suggest that the novel composites possess huge potential for antibiotics wastewater treatment.

MINERAL PARAGENESIS OF FINE-GRAINED PRECIPITATES IN PERMEABLE REACTIVE BARRIERS OF ZERO-VALENT IRON

EPA Science Inventory

U.S. EPA (Environmental Protection Agency) staff developed a field procedure to measure hydraulic conductivity using a direct-push system to obtain vertical profiles of hydraulic conductivity. Vertical profiles were obtained using an in situ field device-composed of a
Geopr...

GROUND WATER ARSENIC AND METALS TREATMENT USING A COMBINATION COMPOST-ZVI PRB (ABSTRACT ONLY)

EPA Science Inventory

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

Remediation of Explosives Contaminated Groundwater With Zero-Valent Iron

DTIC Science & Technology

2011-10-01

1947. Howson, P.E., Mackenzie, P.D. and Horney, D.P., 1996. Enhanced reactive metal wall for dehalogenation of hydrocarbons. Tertiary Enhanced...reactive metal wall for dehalogenation of hydrocarbons, United States. Hundal, L.S., Singh, J., Bier, E.L., Shea, P.J., Comfort, S.D. and Power, W.L

Dechlorination Kinetics Of Monochlorobiphenyls By Fe/Pd: Effects Of Solvent, Temperature, And PCB Concentration

EPA Science Inventory

Well-known, yet undefined, changes in the conditions and activity of palladized zerovalent iron (Fe/Pd) over an extended period of time hindered a careful study of dechlorination kinetics in long-term experiments. A short-term experimental method was, therefore, developed to stud...

LABORATORY EVALUATION OF ZERO-VALENT IRON TO TREAT GROUNDWATER IMPACTED BY ACID MINE DRAINAGE

EPA Science Inventory

The generation and release of acidic, metal-rich water from mine wastes continues to be an intractable environmental problem. Although the effects of acid mine drainage (AMD) are most evident in surface waters, there is an obvious need for developing cost-effective approaches fo...

Metal organic frameworks (MOFs) for degradation of nerve agent simulant parathion

USDA-ARS?s Scientific Manuscript database

Parathion, a simulant of nerve agent VX, has been studied for degradation on Fe3+, Fe2+ and zerovalent iron supported on chitosan. Chitosan, a naturally occurring biopolymer derivative of chitin, is a very good adsorbent for many chemicals including metals. Chitosan is used as supporting biopolymer ...

Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVI-Compost PRB

EPA Science Inventory

A 30-month performance evaluation of a pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel installed at a former phosphate fertilizer manufacturing facility was conducted. The PRB is designed to remove ...

TREATMENT OF ARSENIC AND METALS IN GROUND WATER USING A COMPOST-ZVI PRB

EPA Science Inventory

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

TREATMENT OF ARSENIC AND METALS IN GROUND WATER USING A COMPOST/ZVI PRB

EPA Science Inventory

A pilot permeable reactive barrier (PRB) consisting of a mixture of 30% yard waste compost, 20% zero-valent iron (ZVI), 5% limestone and 45% pea gravel by volume was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The pilo...

GROUND WATER ARSENIC AND METALS TREATMENT USING A COMBINATION COMPOST-ZVI PRB

EPA Science Inventory

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel was installed at a former phosphate fertilizer manufacturing facility in Charleston, S.C. in September 2002. The PRB is designed to treat arsenic an...

Metal organic frameworks (MOFs) for degrdation of nerve agent simulant parathion

USDA-ARS?s Scientific Manuscript database

Parathion, a simulant of nerve agent VX, has been studied for degradation on Fe3+, Fe2+ and zerovalent iron supported on chitosan. Chitosan, a naturally occurring biopolymer derivative of chitin, is a very good adsorbent for many chemicals including metals. Chitosan is used as supporting biopolymer ...

SPATIAL AND TEMPORAL TRENDS IN GROUNDWATER CHEMISTRY AND PRECIPITATE FORMATION AT THE ELIZABETH CITY PERMEABLE REACTIVE BARRIER

EPA Science Inventory

Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of PRBs. Both processes can impact remedial performance by affecting zero-valent iron reactivity and permeability. Results will be presented from solid-phase and gro...

The Use of Molecular and Genomic Techniques Applied to Microbial Diversity, Community Structure, and Activities at DNAPL and Metal Contaminated Sites

EPA Science Inventory

A wide variety of in situ subsurface remediation strategies have been developed to mitigate contamination by chlorinated solvent dense non-aqueous phase liquids (DNAPLS) and metals. Geochemical methods include: zerovalent iron emplacement, various electrolytic applications, elec...

Field test on the treatment of source zone chloroethenes using emulsified zerovalent iron

EPA Science Inventory

This talk summarizes the research activities currently underway at the Solid Waste Management Unit 45 (Site 45), Marine Corps Recruit Depot, Parris Island, South Carolina. A pilot field test was initiated in 2005 at this site to evaluate the effectiveness of nanoscale emulsified...

Measuring the reactivity of commercially available zero-valent iron nanoparticles used for environmental remediation with iopromide.

PubMed

Schmid, Doris; Micić, Vesna; Laumann, Susanne; Hofmann, Thilo

2015-10-01

The high specific surface area and high reactivity of nanoscale zero-valent iron (nZVI) particles have led to much research on their application to environmental remediation. The reactivity of nZVI is affected by both the water chemistry and the properties of the particular type of nZVI particle used. We have investigated the reactivity of three types of commercially available Nanofer particles (from Nanoiron, s.r.o., Czech Republic) that are currently either used in, or proposed for use in full scale environmental remediation projects. The performance of one of these, the air-stable and thus easy-to-handle Nanofer Star particle, has not previously been reported. Experiments were carried out first in batch shaking reactors in order to derive maximum reactivity rates and provide a rapid estimate of the Nanofer particle's reactivity. The experiments were performed under near-natural environmental conditions with respect to the pH value of water and solute concentrations, and results were compared with those obtained using synthetic water. Thereafter, the polyelectrolyte-coated Nanofer 25S particles (having the highest potential for transport within porous media) were chosen for the experiments in column reactors, in order to elucidate nanoparticle reactivity under a more field-site realistic setting. Iopromide was rapidly dehalogenated by the investigated nZVI particles, following pseudo-first-order reaction kinetics that was independent of the experimental conditions. The specific surface area normalized reaction rate constant (kSA) value in the batch reactors ranged between 0.12 and 0.53Lm(-2)h(-1); it was highest for the uncoated Nanofer 25 particles, followed by the polyacrylic acid-coated Nanofer 25S and air-stable Nanofer Star particles. In the batch reactors all particles were less reactive in natural water than in synthetic water. The kSA values derived from the column reactor experiments were about 1000 times lower than those from the batch reactors, ranging between 2.6×10(-4) and 5.7×10(-4)Lm(-2)h(-1). Our results revealed that the easy-to-handle and air-stable Nanofer Star particles are the least reactive of all the Nanofer products tested. The reaction kinetics predicted by column experiments were more realistic than those predicted by batch experiments and these should therefore be used when designing a full-scale field application of nanomaterials for environmental remediation. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

2013-01-01

Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts. Preferably, the hydrogenation catalyst is a bimetallic particle formed from a zero-valent iron or zero-valent magnesium particle coated with palladium that is impregnated onto a high-surface-area graphite support. The zero-valent metal particles should be microscale or nanoscale zero-valent magnesium or zero-valent iron particles. Other zero-valent metal particles and combinations may be used. Additionally, the base material may be selected from a variety of minerals including, but not limited to, alumina and zeolites. The catalytic metal is preferably selected from the group consisting of noble metals and transition metals, preferably palladium. The mechanical milling process includes milling the base material with a catalytic metal impregnated into a high-surface-area support to form the hydrogenation catalyst. In a preferred mechanical milling process, a zero-valent metal particle is provided as the base material, preferably having a particle size of less than about 10 microns, preferably 0.1 to 10 microns or smaller, prior to milling. The catalytic metal is supported on a conductive carbon support structure prior to milling. For example, palladium may be impregnated on a graphite support. Other support structures such as semiconductive metal oxides may also be used.

Zero-valent Fe confined mesoporous silica nanocarriers (Fe(0) @ MCM-41) for targeting experimental orthotopic glioma in rats

PubMed Central

Shevtsov, M. A.; Parr, M. A.; Ryzhov, V. A.; Zemtsova, E. G.; Arbenin, A. Yu; Ponomareva, A. N.; Smirnov, V. M.; Multhoff, G.

2016-01-01

Mesoporous silica nanoparticles (MSNs) impregnated with zero-valent Fe (Fe(0) @ MCM-41) represent an attractive nanocarrier system for drug delivery into tumor cells. The major goal of this work was to assess whether MSNs can penetrate the blood-brain barrier in a glioblastoma rat model. Synthesized MSNs nanomaterials were characterized by energy dispersive X-ray spectroscopy, measurements of X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. For the detection of the MSNs by MR and for biodistribution studies MSNs were labeled with zero-valent Fe. Subsequent magnetometry and nonlinear-longitudinal-response-M2 (NLR-M2) measurements confirmed the MR negative contrast enhancement properties of the nanoparticles. After incubation of different tumor (C6 glioma, U87 glioma, K562 erythroleukemia, HeLa cervix carcinoma) and normal cells such as fibroblasts and peripheral blood mononuclear cells (PBMCs) MSNs rapidly get internalized into the cytosol. Intracellular residing MSNs result in an enhanced cytotoxicity as Fe(0) @ MCM-41 promote the reactive oxygen species production. MRI and histological studies indicated an accumulation of intravenously injected Fe(0) @ MCM-41 MSNs in orthotopic C6 glioma model. Biodistribution studies with measurements of second harmonic of magnetization demonstrated an increased and dose-dependent retention of MSNs in tumor tissues. Taken together, this study demonstrates that MSNs can enter the blood-brain barrier and accumulate in tumorous tissues. PMID:27386761

Effects of dissolved oxygen on dye removal by zero-valent iron.

PubMed

Wang, Kai-Sung; Lin, Chiou-Liang; Wei, Ming-Chi; Liang, Hsiu-Hao; Li, Heng-Ching; Chang, Chih-Hua; Fang, Yung-Tai; Chang, Shih-Hsien

2010-10-15

Effects of dissolved oxygen concentrations on dye removal by zero-valent iron (Fe(0)) were investigated. The Vibrio fischeri light inhibition test was employed to evaluate toxicity of decolorized solution. Three dyes, Acid Orange 7 (AO7, monoazo), Reactive Red 120 (RR120, diazo), and Acid Blue 9 (AB9, triphenylmethane), were selected as model dyes. The dye concentration and Fe(0) dose used were 100 mg L(-1) and 30 g L(-1), respectively. Under anoxic condition, the order for dye decolorization was AO7>RR120>AB9. An increase in the dissolved oxygen concentrations enhanced decolorization and chemical oxygen demand (COD) removal of the three dyes. An increase in gas flow rates also improved dye and COD removals by Fe(0). At dissolved oxygen of 6 mg L(-1), more than 99% of each dye was decolorized within 12 min and high COD removals were obtained (97% for AO7, 87% for RR120, and 93% for AB9). The toxicity of decolorized dye solutions was low (I(5)<40%). An increase in DO concentrations obviously reduced the toxicity. When DO above 2 mg L(-1) was applied, low iron ion concentration (13.6 mg L(-1)) was obtained in the decolorized AO7 solution. 2010 Elsevier B.V. All rights reserved.

DDT degradation efficiency and ecotoxicological effects of two types of nano-sized zero-valent iron (nZVI) in water and soil.

PubMed

El-Temsah, Yehia S; Sevcu, Alena; Bobcikova, Katerina; Cernik, Miroslav; Joner, Erik J

2016-02-01

Nano-scale zero-valent iron (nZVI) has been conceived for cost-efficient degradation of chlorinated pollutants in soil as an alternative to e.g permeable reactive barriers or excavation. Little is however known about its efficiency in degradation of the ubiquitous environmental pollutant DDT and its secondary effects on organisms. Here, two types of nZVI (type B made using precipitation with borohydride, and type T produced by gas phase reduction of iron oxides under H2) were compared for efficiency in degradation of DDT in water and in a historically (>45 years) contaminated soil (24 mg kg(-1) DDT). Further, the ecotoxicity of soil and water was tested on plants (barley and flax), earthworms (Eisenia fetida), ostracods (Heterocypris incongruens), and bacteria (Escherichia coli). Both types of nZVI effectively degraded DDT in water, but showed lower degradation of aged DDT in soil. Both types of nZVI had negative impact on the tested organisms, with nZVI-T giving least adverse effects. Negative effects were mostly due to oxidation of nZVI, resulting in O2 consumption and excess Fe(II) in water and soil. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

One-pot synthesis of ternary zero-valent iron/phosphotungstic acid/g-C3N4 composite and its high performance for removal of arsenic(V) from water

NASA Astrophysics Data System (ADS)

Chen, Chunhua; Xu, Jia; Yang, Zhihua; Zhang, Li; Cao, Chunhua; Xu, Zhihua; Liu, Jiyan

2017-12-01

Ternary zero-valent iron/phos photungstic acid/g-C3N4 composite (Fe0@PTA/g-C3N4) was synthesized via photoreduction of iron (II) ions assisted by phosphotungstic acid (PTA) over g-C3N4 flakes. The as-prepared Fe0@PTA/g-C3N4 was investigated for removal of As(III) and As(V) species from water. The result showed that Fe0@PTA/g-C3N4 exhibited a better performance for As(V) removal than As(III) species from water, and the maximum adsorption capacity for As(V) was 70.3 mg/g, much higher than most of the reported adsorbents. As(V) removal by the Fe0@PTA/g-C3N4 adsorbent is mainly via a chemical process, synergistically occurring of reduction of As(V) and oxidation of Fe0. Moreover, the Fe0@PTA/g-C3N4 adsorbent showed effective As(V) removal from the simulated industrial wastewater and underground water. This study demonstrates that Fe0@PTA/g-C3N4 can be a potential adsorbent for As(V) removal due to its high performance, and simple one-pot synthesis process.

Perchlorate reduction by autotrophic bacteria in the presence of zero-valent iron.

PubMed

Yu, Xueyuan; Amrhein, Christopher; Deshusses, Marc A; Matsumoto, Mark R

2006-02-15

A series of batch experiments were performed to study the combination of zero-valent iron (ZVI) with perchlorate-reducing microorganisms (PRMs) to remove perchlorate from groundwater. In this method, H2 produced during the process of iron corrosion by water is used by PRMs as an electron donor to reduce perchlorate to chloride. Perchlorate degradation rates followed Monod kinetics, with a normalized maximum utilization rate (rmax) of 9200 microg g(-1) (dry wt) h(-1) and a half-velocity constant (Ks) of 8900 microg L(-1). The overall rate of perchlorate reduction was affected by the biomass density within the system. An increase in the OD600 from 0.025 to 0.08 led to a corresponding 4-fold increase of perchlorate reduction rate. PRM adaptation to the local environment and initiation of perchlorate reduction was rapid under neutral pH conditions. At the initial OD600 of 0.015, perchlorate reduction followed pseudo-first-order reaction rates with constants of 0.059 and 0.033 h(-1) at initial pH 7 and 8, respectively. Once perchlorate reduction was established, the bioreductive process was insensitive to the increases of pH from near neutral to 9.0. In the presence of nitrate, perchlorate reduction rate was reduced, but not inhibited completely.

INFLUENCE OF GROUNDWATER GEOCHEMISTRY ON THE LONG-TERM PERFORMANCE OF IN-SITU PERMEABLE REACTIVE BARRIERS CONTAINING ZERO-VALENT IRON

EPA Science Inventory

Reactive barriers that couple subsurface fluid flow with a passive chemical treatment zone are emerging, cost effective approaches for in-situ remediation of contaminated groundwater. Factors such as the build-up of surface precipitates, bio-fouling, and changes in subsurface tr...

Simultaneous Removal of Nitrogen and Phosphorus from Stormwater by ZeroValent Iron and Biochar in Bioretention Cells (Part 1)

DOT National Transportation Integrated Search

2016-06-03

Nutrients (N and P) in stormwater are a major cause of water quality impairments in the U.S. Current technologies such as bioretention cells to treat stormwater from roadways do not always remove nutrients sufficiently, and additional land may be nee...

TREATMENT OF METALS IN GROUND WATER USING AN ORGANIC-BASED SULFATE-REDUCING PERMEABLE REACTIVE BARRIER

EPA Science Inventory

A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI) filings, limestone and pea gravel was evaluated at a former phosphate fertilizer manufacturing facility in Charleston, S.C. The PRB is designed to treat arsenic and heavy met...

LONG-TERM GEOCHEMICAL BEHAVIOR OF A ZEROVALENT IRON PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM IN GROUNDWATER

EPA Science Inventory

Passive, in-situ reactive barriers have proven to be viable, cost-effective systems for the remediation of Cr-contaminated groundwater at some sites. Permeable reactive barriers (PRBs) are installed in the flow-path of groundwater, most typically as vertical treatment walls. Re...

Remediation of TNT and RDX in Groundwater Using Zero-Valent Iron Permeable Reactive Barriers

DTIC Science & Technology

2008-04-01

3 3.0 TECHNOLOGY DESCRIPTION ...................................................................................... 5 3.1... hydroxide NAVFAC-ESC Naval Facilities Engineering Service Center O&M operation and maintenance OHSU Oregon Health and Science University OD...remediation costs that may jeopardize major DoD programs and initiatives. 3 This page left blank intentionally. 3.0 TECHNOLOGY DESCRIPTION

Degradation Kinetics of Carbon Tetrachloride by Sulfate Green Rust as Influenced by pH and Copper Ions (Stillwater)

EPA Science Inventory

Chlorinated solvents such as trichloroethene (TCE, C2HCl3) and carbon tetrachloride (CT, CCl4) are priority groundwater contaminants at many EPA field sites. Green rust (GR) minerals are important corrosion products of zerovalent iron (Fe0) that has been used in permeable react...

Formation Processes and Impacts of Reactive and Nonreactive Minerals in Permeable Reactive Barriers

EPA Science Inventory

Mineral precipitates in zero-valent iron PRBs can be classified by formation processes into three groups: 1) those that result from changes in chemical conditions (i.e., changes in pH, e.g., calcite); 2) those that are a consequence of microbial activity (i.e., sulfate reduction,...

FORMATION PROCESSES AND CONSEQUENCES OF REACTIVE AND NON-REACTIVE MINERAL PRECIPITATES IN PERMEABLE REACTIVE BARRIERS

EPA Science Inventory

Mineral precipitates in zero-valent iron PRBs can be classified by formation processes into three groups: 1) those that result from changes in chemical conditions (i.e., change in pH, e.g., calcite); 2) those that are a consequence of microbial activity (i.e., sulfate reduction, ...

Degradation Kinetics of Carbon Tetrachloride by Sulfate Green Rust as Influenced by pH and Copper Ions

EPA Science Inventory

Chlorinated solvents such as trichloroethene (TCE, C2HCl3) and carbon tetrachloride (CT, CCl4) are priority groundwater contaminants at many EPA field sites. Green rust (GR) minerals are important corrosion products of zerovalent iron (Fe0) that has been used in permeable reactiv...

Molecular stress responses to nano-sized zero-valent iron (nZVI) particles in the soil bacterium Pseudomonas stutzeri.

PubMed

Saccà, Maria Ludovica; Fajardo, Carmen; Martinez-Gomariz, Montserrat; Costa, Gonzalo; Nande, Mar; Martin, Margarita

2014-01-01

Nanotoxicological studies were performed in vitro using the common soil bacterium Pseudomonas stutzeri to assess the potentially toxic impact of commercial nano-sized zero-valent iron (nZVI) particles, which are currently used for environmental remediation projects. The phenotypic response of P. stutzeri to nZVI toxicity includes an initial insult to the cell wall, as evidenced by TEM micrographs. Transcriptional analyses using genes of particular relevance in cellular activity revealed that no significant changes occurred among the relative expression ratios of narG, nirS, pykA or gyrA following nZVI exposure; however, a significant increase in katB expression was indicative of nZVI-induced oxidative stress in P. stutzeri. A proteomic approach identified two major defence mechanisms that occurred in response to nZVI exposure: a downregulation of membrane proteins and an upregulation of proteins involved in reducing intracellular oxidative stress. These biomarkers served as early indicators of nZVI response in this soil bacterium, and may provide relevant information for environmental hazard assessment.

Molecular Stress Responses to Nano-Sized Zero-Valent Iron (nZVI) Particles in the Soil Bacterium Pseudomonas stutzeri

PubMed Central

Saccà, Maria Ludovica; Fajardo, Carmen; Martinez-Gomariz, Montserrat; Costa, Gonzalo; Nande, Mar; Martin, Margarita

2014-01-01

Nanotoxicological studies were performed in vitro using the common soil bacterium Pseudomonas stutzeri to assess the potentially toxic impact of commercial nano-sized zero-valent iron (nZVI) particles, which are currently used for environmental remediation projects. The phenotypic response of P. stutzeri to nZVI toxicity includes an initial insult to the cell wall, as evidenced by TEM micrographs. Transcriptional analyses using genes of particular relevance in cellular activity revealed that no significant changes occurred among the relative expression ratios of narG, nirS, pykA or gyrA following nZVI exposure; however, a significant increase in katB expression was indicative of nZVI-induced oxidative stress in P. stutzeri. A proteomic approach identified two major defence mechanisms that occurred in response to nZVI exposure: a downregulation of membrane proteins and an upregulation of proteins involved in reducing intracellular oxidative stress. These biomarkers served as early indicators of nZVI response in this soil bacterium, and may provide relevant information for environmental hazard assessment. PMID:24586957

Immobilization of chromate in hyperalkaline waste streams by green rusts and zero-valent iron.

PubMed

Rogers, Christine M; Burke, Ian T; Ahmed, Imad A M; Shaw, Samuel

2014-01-01

Zero-valent iron (ZVI) and green rusts can be used as reductants to convert chromium from soluble, highly toxic Cr(VI) to insoluble Cr(III). This study compared the reduction rates of Cr(VI) by ZVI and two carbonate green rust phases in alkaline/hyperalkaline solutions. Batch experiments were carried out with synthetic chromate solutions at pH 7.7-12.3 and a chromite ore processing residue (COPR) leachate (pH approximately 12.2). Green rust removes chromate from high pH solutions (pH 10-12.5) very rapidly (<400 s). Chromate reduction rates for both green rust phases were consistently higher than for ZVI throughout the pH range studied; the surface area normalized rate constants were two orders of magnitude higher in the COPR leachate solution at pH 12.2. The performances of both green rusts were unaffected by changes in pH. In contrast, ZVI exhibited a marked decline in reduction rate with increasing pH to become almost ineffective above pH12.

Inhibiting excessive acidification using zero-valent iron in anaerobic digestion of food waste at high organic load rates.

PubMed

Kong, Xin; Wei, Yonghong; Xu, Shuang; Liu, Jianguo; Li, Huan; Liu, Yili; Yu, Shuyao

2016-07-01

Excessive acidification occurs frequently in food waste (FW) anaerobic digestion (AD) due to the high carbon-to-nitrogen ratio of FW. In this study, zero-valent iron (ZVI) was applied to prevent the excessive acidification. All of the control groups, without ZVI addition (pH∼5.3), produced little methane (CH4) and had high volatile fatty acids/bicarbonate alkalinity (VFA/ALK). By contrast, at OLR of 42.32gVS/Lreactor, the pH of effluent from the reactors with 0.4g/gVSFWadded of ZVI increased to 7.8-8.2, VFA/ALK decreased to <0.1, and the final CH4 yield was ∼380mL/gVSFWadded, suggesting inhibition of excessive acidification. After adding powdered or scrap metal ZVI to the acidogenic reactors, the fractional content of butyric acid changed from 30-40% to 0%, while, that of acetic acid increased. These results indicate that adding ZVI to FW digestion at high OLRs could eliminate excessive acidification by promoting butyric acid conversion and enhancing methanogen activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Enhanced remediation of 4-chloronitrobenzene contaminated groundwater with nanoscale zero-valence iron (nZVI) catalyzed hydrogen peroxide (H2O2)].

PubMed

Fu, Rong-Bing

2014-04-01

Chemical oxidation-reduction technology is an important way to quickly remedy contaminated groundwater. Nanoscale zero-valent iron (nZVI) was produced by liquid-phase reduction using FeSO4 and NaBH4, and characterized by SEM and XRD. The remediation of 4-chloronitrobezene (4-CINB) contaminated groundwater at ambient temperature and pressure was conducted with the nZVI catalytic H2O2 process, and the affecting factors and degradation mechanisms were investigated. The results indicated that under initial pH 3.0 at the temperature of 30 degrees C, after 30 mins of reaction, 4-ClNB in groundwater was completely degraded when the concentrations of nZVI and H2O2 were 268.8 mg x L(-1) and 4.90 mmol x L(-1), respectively. 4-chloronitrosobenzene, 4-chlorophenylhydroxylamine, 4-chloroazoxybenzene, 4-chloroaniline, 4-chloroazobenzene, 4-benzoquinone, acetic acid, formic acid, oxalic acid and chlorine ion were identified as the major intermediates of 4-ClNB degradation after the process. A tentative pathway for the degradation of 4-ClNB was proposed.

Treatment of simulated wastewater containing Reactive Red 195 by zero-valent iron/activated carbon combined with microwave discharge electrodeless lamp/sodium hypochlorite.

PubMed

Fu, Jie; Xu, Zhen; Li, Qing-Shan; Chen, Song; An, Shu-Qing; Zeng, Qing-Fu; Zhu, Hai-Liang

2010-01-01

A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon (ZVI/AC), microwave discharge electrodeless lamp/sodium hypochlorite (MDEL/NaClO) and the combination of ZVI/AC-MDEL/NaClO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaClO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaClO, we found that in the ZVI/AC-MEDL/NaClO process, ZVI/AC could break the azo bond firstly and then MEDL/NaClO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.

Assessing the impact of nano- and micro-scale zerovalent iron particles on soil microbial activities: particle reactivity interferes with assay conditions and interpretation of genuine microbial effects.

PubMed

Cullen, Laurence G; Tilston, Emma L; Mitchell, Geoff R; Collins, Chris D; Shaw, Liz J

2011-03-01

The effects of nano-scale and micro-scale zerovalent iron (nZVI and mZVI) particles on general (dehydrogenase and hydrolase) and specific (ammonia oxidation potential, AOP) activities mediated by the microbial community in an uncontaminated soil were examined. nZVI (diameter 12.5 nm; 10 mg g⁻¹ soil) apparently inhibited AOP and nZVI and mZVI apparently stimulated dehydrogenase activity but had minimal influence on hydrolase activity. Sterile experiments revealed that the apparent inhibition of AOP could not be interpreted as such due to the confounding action of the particles, whereas, the nZVI-enhanced dehydrogenase activity could represent the genuine response of a stimulated microbial population or an artifact of ZVI reactivity. Overall, there was no evidence for negative effects of nZVI or mZVI on the processes studied. When examining the impact of redox active particles such as ZVI on microbial oxidation-reduction reactions, potential confounding effects of the test particles on assay conditions should be considered. Copyright © 2010 Elsevier Ltd. All rights reserved.

Delineation of Groundwater Flow Pathway in Fractured Bedrock Using Nano-Iron Tracer Test in the Sealed Well

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Chiu, Yung-Chia; Liou, Ya-Hsuan; Teng, Mao-Hua; Liu, Ching-Yi; Lee, Tsai-Ping

2016-04-01

Deterministic delineation of the preferential flow paths and their hydraulic properties are desirable for developing hydrogeological conceptual models in bedrock aquifers. In this study, we proposed using nanoscale zero-valent iron (nZVI) as a tracer to characterize the fractured connectivity and hydraulic properties. Since nZVI particles are magnetic, we designed a magnet array to attract the arriving nZVI particles in the observation well for identifying the location of incoming tracer. This novel approach was examined at two experiment wells with well hydraulic connectivity in a hydrogeological research station in the fractured aquifer. Heat-pulse flowmeter test was used to detect the vertical distribution of permeable zones in the borehole, providing the design basis of tracer test. Then, the less permeable zones in the injection well were sealed by casing to prevent the injected nZVI particles from being stagnated at the bottom hole. Afterwards, hydraulic test was implemented to examine the hydraulic connectivity between two wells. When nZVI slurry was released in the injection well, they could migrate through connected permeable fractures to the observation well. A breakthrough curve was obtained by the fluid conductivity sensor in the observation well, indicating the arrival of nZVI slurry. The iron nanoparticles that were attracted to the magnets in the observation well provide the quantitative information to locate the position of tracer inlet, which corroborates well with the depth of a permeable zone delineated by the flowmeter. Finally, the numerical method was utilized to simulate the process of tracer migration. This article demonstrates that nano-iron tracer test can be a promising approach for characterizing connectivity patterns and transmissivities of the flow paths in the fractured rock.

Rapid debromination of polybrominated diphenyl ethers (PBDEs) by zero valent metal and bimetals: Mechanisms and pathways assisted by density function theory calculation.

PubMed

Wang, Rui; Tang, Ting; Lu, Guining; Huang, Kaibo; Yin, Hua; Lin, Zhang; Wu, Fengchang; Dang, Zhi

2018-05-17

Polybrominated diphenyl ethers (PBDEs) undergo debromination when they were exposed in zerovalent metal or bimetallic systems. Yet their debromination pathways and mechanisms in these systems were not well understood. Here we reported the debromination pathways of three BDE congeners (BDE-21, 25 and 29) by nano-zerovalent iron (n-ZVI). All these BDE congeners have three bromine substituents that were located in ortho-, meta- and para-positions. Results demonstrated that BDE-21, 25 and 29 preferentially debrominate meta-, ortho- and para-bromines, respectively, suggesting that bromine substituent at each position (i.e. ortho-, meta- or para-) of PBDEs can be preferentially removed. Singly occupied molecular orbitals of BDE anions are well correlated with their actual debromination pathways, which successfully explain why these BDE congeners exhibit certain debromination pathways in n-ZVI system. In addition, microscale zerovalent zinc (m-ZVZ), iron-based bimetals (Fe/Ag and Fe/Pd) were also used to debrominate PBDEs, with BDE-21 as target pollutant. We found that the debromination pathways of BDE-21 in m-ZVZ and Fe/Ag systems are the same to those in n-ZVI system, but were partially different from those in Fe/Pd systems. The debromination of BDE-21 in Pd-H 2 system as well as the solvent kinetic isotope effect in single metal and bimetallic systems suggests that H atom transfer is the dominant mechanism in Fe/Pd system, while e-transfer is still the dominant mechanism in Fe/Ag system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Zero-valent iron-biosand filtration is capable of reducing antimicrobials and generic E. coli concentrations in unbuffered conventionally-treated reclaimed water: a CONSERVE project

USDA-ARS?s Scientific Manuscript database

Introduction: If conventionally treated reclaimed water (RW) is to be adopted as analternative to freshwater irrigation, it is necessary to investigate reuse site-based mitigation options that can further reduce contaminantssuch as foodborne pathogens andpharmaceuticals and personal care products (P...

Performance of a Zerovalent Iron Reactive Barrier for the Treatment of Arsenic in Groundwater: Part 1. Hydrogeochemical Studies

EPA Science Inventory

Developments and improvements of remedial technologies are needed to effectively manage arsenic contamination in groundwater at hazardous waste sites. In June 2005, a 9.1 m long, 14 m deep, and 1.8 to 2.4 m wide (in the direction of groundwater flow) pilot-scale permeable reacti...

Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron     

EPA Science Inventory

Zero-valent iron (nZVI) is a redox-active nanomaterial used for in situ remediation of contaminated groundwater. To assess the effect of “aging” and surface modification on its potential neurotoxicity, cultured rodent microglia and neurons were exposed to fresh nZVI, “aged” (>11...

Rational synthesis of zerovalent iron/bamboo charcoal composites with high saturation magnetization

Treesearch

Mingshan Wu; Jianfeng Ma; Zhiyong Cai; Genlin Tian; Shumin Yang; Youhong Wang; Xing' e Liu

2015-01-01

The synthesis of magnetic biochar composites is a major new research area in advanced materials sciences. A series of magnetic bamboo charcoal composites (MBC800, MBC1000 and MBC1200) with high saturation magnetization (Ms) was fabricated in this work by mixing bamboo charcoal powder with an aqueous ferric chloride solution and subsequently...

THE APPLICATION OF PRB TECHNOLOGY AT TWO SITES: LESSONS LEARNED AFTER 7 YEARS OF PERFORMANCE MONITORING

EPA Science Inventory

In June of 1996, a 46 m long, 7.3 m deep, and 0.6 m wide permeable reactive barrier (continuous wall configuration) of zero-valent iron was installed at the USCG-SC site. The reactive wall was designed to remediate hexavalent chromium-contaminated groundwater, in addition to tre...

Dissolution of realgar by Acidithiobacillus ferrooxidans in the presence and absence of zerovalent iron: Implications for remediation of iron-deficient realgar tailings.

PubMed

Fan, Lijun; Zhao, Fenghua; Liu, Jing; Hudson-Edwards, Karen A

2018-06-06

Realgar (As 4 S 4 )-rich tailings are iron-deficient arsenical mine wastes. The mechanisms and products of the dissolution of realgar by Acidithiobacillus ferrooxidans (A. ferrooxidans) in the presence (0.2 g and 2 g) and absence of zerovalent iron (ZVI) are investigated for three stages (each of 7 d with fresh A. ferrooxidans medium addition between the stages). SEM-EDX, FTIR, XPS and selective extraction analysis are used to characterize the solid-phase during the experiments. ZVI addition causes the systems to become more acid-generating, although pH increases are observed in the first day due to ZVI dissolution. Arsenic is released to solution due to realgar oxidation (∼30 mg L -1 in the 0 g ZVI system in Stage I), but low concentrations are observed in the ZVI-added systems (<5 mg L -1 ) and in Stages II and III of the 0 g ZVI system. As(III) dominates the released As(T) at day 1 (83-89% of As(T)), but is largely oxidized to As(V) at day 7 of each stage (53-98% of As(T)). Arsenic attenuation is attributed to the formation of mixed As-Fe oxyhydroxides and oxyhydroxy sulfates that take up released arsenic and are abundant in the 2.0 g ZVI system, and to passivation of the realgar surface. Consequently, a new strategy that combines A. ferrooxidans and exogenous ZVI addition for treating in-situ iron-deficient realgar-rich tailings is proposed, although its long-term effects need to be monitored. Copyright © 2018 Elsevier Ltd. All rights reserved.

Catalytic degradation of brominated flame retardants by copper oxide nanoparticles

NASA Astrophysics Data System (ADS)

Dror, I.; Yecheskel, Y.; Berkowitz, B.

2013-12-01

Brominated flame retardants (BFRs) have been added to various products like plastic, textile, electronics and synthetic polymers at growing rates. In spite of the clear advantages of reducing fire damages, many of these BFRs may be released to the environment after their beneficial use which may lead to contamination of water resources. In this work we present the catalytic degradation of two brominated flame retardants (BFRs), tribromoneopentyl alcohol (TBNPA) and 2,4 dibromophenol (2,4-DBP) by copper oxide nanoparticles (nCuO) in aqueous solution. The degradation kinetics, the debromination, and the formation of intermediates by nCuO catalysis are compared to Fenton oxidation and to reduction by nano zero-valent iron (nZVI). The two studied BFRs are shown to degrade fully by the nCuO system within hours to days. Shorter reaction times showed differences in reaction pathways and kinetics for the two compounds. The 2,4-DBP showed faster degradation than TBNPA, by nCuO catalysis. Relatively high resistance to degradation was recorded for 2,4-DBP with nZVI, yielding 20% degradation after 24 h, while the TBNPA was degraded by 85% within 12 hours. A catalytic mechanism for radical generation and BFR degradation by nCuO is proposed. It is further suggested that H2O2 plays an essential role in the activation of the catalyst.

Nanosized zero-valent iron as Fenton-like reagent for ultrasonic-assisted leaching of zinc from blast furnace sludge.

PubMed

Mikhailov, Ivan; Komarov, Sergey; Levina, Vera; Gusev, Alexander; Issi, Jean-Paul; Kuznetsov, Denis

2017-01-05

Ultrasonic-assisted sulphuric acid leaching combined with a Fenton-like process, utilizing nanoscale zero-valent iron (nZVI), was investigated to enhance the leaching of zinc from the blast furnace sludge (BFS). The leaching of iron (Fe) and zinc (Zn) from the sludge was investigated using Milli-Q water/BFS ratio of 10 and varying the concentration of hydrogen peroxide, sulphuric acid, the temperature, the input energy for ultrasound irradiation, and the presence or absence of nZVI as a Fenton reagent. The results showed that with 1g/l addition of nZVI and 0.05M of hydrogen peroxide, the kinetic rate of Zn leaching increased with a maximum dissolution degree of 80.2%, after 5min treatment. In the absence of nZVI, the maximum dissolution degree of Zn was 99.2%, after 15min treatment with 0.1M of hydrogen peroxide. The rate of Zn leaching at several concentrations of hydrogen peroxide is accelerated in the presence of nZVI although a reduction in efficiency was observed. The loss of Fe was no more than 3%. On the basis of these results, the possible route for BFS recycling has been proposed (BFS slurry mixed with sulphuric acid and hydrogen peroxide is recirculated under ultrasonic irradiation then separated). Copyright © 2016 Elsevier B.V. All rights reserved.

The reproductive responses of earthworms (Eisenia fetida) exposed to nanoscale zero-valent iron (nZVI) in the presence of decabromodiphenyl ether (BDE209).

PubMed

Liang, Jun; Xia, Xiaoqian; Yuan, Ling; Zhang, Wei; Lin, Kuangfei; Zhou, Bingsheng; Hu, Shuangqing

2018-06-01

Reproductive toxicity of nanoscale zero-valent iron (nZVI) along with coexisting decabromodiphenyl ether (BDE209) to earthworm Eisenia fetida (E. fetida) remains unknown. In the present study, the reproductive responses of E. fetida exposed to 100, 500 and 1000 mg kg -1 of nZVI showed a significant (P < 0.05) decline up to 35.6%, 60.0% and 93.3%, respectively, compared to the controls. Expression levels of annetocin (ANN) gene indicated a remarkable (P < 0.05) down-regulation (59.2%, 58.2% and 95.0%, correspondingly), and it was positively correlated with reproductive rates (R = 0.94). Iron contents in E. fetida were also relevant to reproductive behavior (R = 0.84) and ANN expression (R = 0.75). Additionally, seminal vesicles displayed a progressive degeneration with increasing nZVI levels. The addition of BDE209 to low level of nZVI-polluted group (100 mg kg -1 dw) barely caused clear changes on reproduction, histopathology and ANN, while the coexistence resulted in significant impacts in comparison with high level of single nZVI exposure (1000 mg kg -1 dw). These observations would provide some significant information concerning joint toxicity of the two chemicals in a soil system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Review on Nano zerovalent Iron (nZVI): From Modification to Environmental Applications

NASA Astrophysics Data System (ADS)

Chen, Xing; Ji, Dandan; Wang, Xiqing; Zang, Lihua

2017-01-01

Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants. Although nZVI particles were successfully used in wastewater treatment, there are still some drawbacks associated with the process and needs to be addressed. For example, magnetic attraction between nanoiron particles causes the rapid aggregation of particles. In addition, nZVI are more prone to react with dissolved oxygen and oxygen-rich compounds. Meantimes, nZVI could exert some degree of toxicity towards microbial species, and the effects of nZVI at the cellular and community levels are progressively being elucidated. To overcome these problems, nZVI particles were immobilized in or on suitable solid supports, and also to expand the effective pH range of the Fenton reaction. Therefore, refer to the new trends is very important when selecting nZVI for the treatment of various matrices. This review also identifies problems that may occurs a result of changes in the physicochemical properties of nZVI due to their modification (e.g. other metal doping, coating the surface, or deposition on the support). Toxicity studies suggest that cellmembrane disruption and oxidative stress through the generation of Fe2+ and reactive oxygen species by nZVI are the main mechanisms contributing to nZVI cytotoxicity. This review highlights the application of nano-zero valent iron in treating refractory compounds.

Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) in a column experiment and a laboratory 2D-aquifer test system.

PubMed

Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E

2014-09-01

Nanoscale zero-valent iron (nZVI) has recently gained great interest in the scientific community as in situ reagent for installation of permeable reactive barriers in aquifer systems, since nZVI is highly reactive with chlorinated compounds and may render them to harmless substances. However, nZVI has a high tendency to agglomerate and sediment; therefore it shows very limited transport ranges. One new approach to overcome the limited transport of nZVI in porous media is using a suited carrier colloid. In this study we tested mobility of a carbon colloid supported nZVI particle "Carbo-Iron Colloids" (CIC) with a mean size of 0.63 μm in a column experiment of 40 cm length and an experiment in a two-dimensional (2D) aquifer test system with dimensions of 110 × 40 × 5 cm. Results show a breakthrough maximum of 82 % of the input concentration in the column experiment and 58 % in the 2D-aquifer test system. Detected residuals in porous media suggest a strong particle deposition in the first centimeters and few depositions in the porous media in the further travel path. Overall, this suggests a high mobility in porous media which might be a significant enhancement compared to bare or polyanionic stabilized nZVI.

Simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewater by zero-valent iron.

PubMed

Yoshino, Hiroyuki; Tokumura, Masahiro; Kawase, Yoshinori

2014-01-01

The zero-valent iron (ZVI) wastewater treatment has been applied to simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewaters. The simultaneous removal occurs by the reactions performed due to the sequential transformation of ZVI under the acidic condition. Fortunately the solution pH of semiconductor acidic wastewaters is low which is effective for the sequential transformation of ZVI. Firstly the reduction of nitrate is taken place by electrons generated by the corrosion of ZVI under acidic conditions. Secondly the ferrous ion generated by the corrosion of ZVI reacts with hydrogen peroxide and generates ·OH radical (Fenton reaction). The Fenton reaction consists of the degradation of hydrogen peroxide and the generation of ferric ion. Finally phosphate precipitates out with iron ions. In the simultaneous removal process, 1.6 mM nitrate, 9.0 mM hydrogen peroxide and 1.0 mM phosphate were completely removed by ZVI within 100, 15 and 15 min, respectively. The synergy among the reactions for the removal of nitrate, hydrogen peroxide and phosphate was found. In the individual pollutant removal experiment, the removal of phosphate by ZVI was limited to 80% after 300 min. Its removal rate was considerably improved in the presence of hydrogen peroxide and the complete removal of phosphate was achieved after 15 min.

Kaolinite-supported nanoscale zero-valent iron for removal of Pb2+ from aqueous solution: reactivity, characterization and mechanism.

PubMed

Zhang, Xin; Lin, Shen; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2011-05-01

The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb(2+) was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb(2+) within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb(2+), various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N(2) method and X-ray diffraction (XRD), were 26.11 m(2)/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb(2+) was adsorbed onto K-nZVI and subsequently reduced to Pb(0). Copyright © 2011 Elsevier Ltd. All rights reserved.

Mechanism insights into enhanced trichloroethylene removal using xanthan gum-modified microscale zero-valent iron particles.

PubMed

Xin, Jia; Han, Jun; Zheng, Xilai; Shao, Haibing; Kolditz, Olaf

2015-03-01

This report focuses on the enhancement in trichloroethylene (TCE) removal from contaminated groundwater using xanthan gum (XG)-modified, microscale, zero-valent iron (mZVI). Compared with bare mZVI, XG-coated mZVI increased the TCE removal efficiency by 30.37% over a 480-h experimental period. Because the TCE removal is attributed to both sorption and reduction processes, the contributions from sorption and reduction were separately investigated to determine the mechanism of XG on TCE removal using mZVI. The results showed that the TCE sorption capacity of mZVI was lower in the presence of XG, whereas the TCE reduction capacity was significantly increased. The FTIR spectra confirmed that XG, which is rich in hydrophilic functional groups, was adsorbed onto the iron surface through intermolecular hydrogen bonds, which competitively repelled the sorption and mass transfer of TCE toward reactive sites. The variations in the pH, Eh, and Fe(2+) concentration as functions of the reaction time were recorded and indicated that XG buffered the solution pH, inhibited surface passivation, and promoted TCE reduction by mZVI. Overall, the XG-modified mZVI was considered to be potentially effective for the in-situ remediation of TCE contaminated groundwater due to its high stability and dechlorination reactivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aqueous Cr(VI) reduction by electrodeposited zero-valent iron at neutral pH: acceleration by organic matters.

PubMed

Liu, Junxi; Wang, Chuan; Shi, Jianying; Liu, Hong; Tong, Yexiang

2009-04-15

This work investigated the effect of co-existing organic matters on aqueous Cr(VI) reduction by electrodeposited zero-valent iron (ED Fe(0)) at neutral pH. The ED Fe(0) prepared in a solution containing mixture of saccharin, L-ascorbic acid and sodium dodecyl sulfate showed higher activity in reducing the aqueous Cr(VI) at neutral pH than that prepared without any organic presence. XRD and SEM indicated that the structure of ED Fe(0) was significantly improved to nano-scale by the presence of organic mixture in the preparation solution. Further, the ED Fe(0) activity in the Cr(VI) reduction at neutral pH was increased by the co-existence of citric acid or oxalic acid in the chromate solution. Electrochemical impedance spectroscopy (EIS) demonstrated that the corrosive current increased with the concentration of organic matter in the reaction solution. With the co-existing organic matters in the preparation solution, the ED Fe(0) corroded more rapidly due to its nano-size, thus the Cr(VI) reduction by the ferrous iron was accelerated. With the co-existing organic matters in the reaction solution, the Cr(VI) reduction was accelerated by a Fe(II) complex as the main electron donor, and a prevention of the passivation due to the Fe(III) and Cr(III) complexes also accelerated the Cr(VI) reduction.

Removal of 2-ClBP from soil-water system using activated carbon supported nanoscale zerovalent iron.

PubMed

Zhang, Wei; Yu, Tian; Han, Xiaolin; Ying, Weichi

2016-09-01

We explored the feasibility and removal mechanism of removing 2-chlorobiphenyl (2-ClBP) from soil-water system using granular activated carbon (GAC) impregnated with nanoscale zerovalent iron (reactive activated carbon or RAC). The RAC samples were successfully synthesized by the liquid precipitation method. The mesoporous GAC based RAC with low iron content (1.32%) exhibited higher 2-ClBP removal efficiency (54.6%) in the water phase. The result of Langmuir-Hinshelwood kinetic model implied that the different molecular structures between 2-ClBP and trichloroethylene (TCE) resulted in more difference in dechlorination reaction rates on RAC than adsorption capacities. Compared to removing 2-ClBP in the water phase, RAC removed the 2-ClBP more slowly in the soil phase due to the significant external mass transfer resistance. However, in the soil phase, a better removal capacity of RAC was observed than its base GAC because the chemical dechlorination played a more important role in total removal process for 2-ClBP. This important result verified the effectiveness of RAC for removing 2-ClBP in the soil phase. Although reducing the total RAC removal rate of 2-ClBP, soil organic matter (SOM), especially the soft carbon, also served as an electron transfer medium to promote the dechlorination of 2-ClBP in the long term. Copyright © 2016. Published by Elsevier B.V.

Simultaneous removal of perchlorate and energetic compounds in munitions wastewater by zero-valent iron and perchlorate-respiring bacteria.

PubMed

Ahn, Se Chang; Hubbard, Brian; Cha, Daniel K; Kim, Byung J

2014-01-01

Ammonium perchlorate is one of the main constituents in Army's insensitive melt-pour explosive, PAX-21 in addition to RDX and 2,4-dinitroanisole (DNAN). The objective of this study is to develop an innovative treatment process to remove both perchlorate and energetic compounds simultaneously from PAX-21 production wastewater. It was hypothesized that the pretreatment of PAX-21 wastewater with zero-valent iron (ZVI) would convert energetic compounds to products that are more amenable for biological oxidation and that these products serve as electron donors for perchlorate-reducing bacteria. Results of batch ZVI reduction experiments showed that DNAN was completely reduced to 2,4-diaminoanisole and RDX was completely reduced to formaldehyde. Anaerobic batch biodegradation experiments showed that perchlorate (30 mg L(-1)) in ZVI-treated PAX-21 wastewater was decreased to an undetectable level after 5 days. Batch biodegradation experiments also confirmed that formaldehyde in ZVI-treated wastewater was the primary electron donor for perchlorate-respiring bacteria. The integrated iron-anaerobic bioreactor system was effective in completely removing energetic compounds and perchlorate from the PAX-21 wastewater without adding an exogenous electron donor. This study demonstrated that ZVI pretreatment not only removed energetic compounds, but also transformed energetic compounds to products that can serve as the source of electrons for perchlorate-respiring bacteria.

Treatment of acid rock drainage using a sulfate-reducing bioreactor with zero-valent iron.

PubMed

Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, James A

2016-05-05

This study assessed the bioremediation of acid rock drainage (ARD) in flow-through columns testing zero-valent iron (ZVI) for the first time as the sole exogenous electron donor to drive sulfate-reducing bacteria in permeable reactive barriers. Columns containing ZVI, limestone or a mixture of both materials were inoculated with an anaerobic mixed culture and fed a synthetic ARD containing sulfuric acid and heavy metals (initially copper, and later also cadmium and lead). ZVI significantly enhanced sulfate reduction and the heavy metals were extensively removed (>99.7%). Solid-phase analyses showed that heavy metals were precipitated with biogenic sulfide in the columns packed with ZVI. Excess sulfide was sequestered by iron, preventing the discharge of dissolved sulfide. In the absence of ZVI, heavy metals were also significantly removed (>99.8%) due to precipitation with hydroxide and carbonate ions released from the limestone. Vertical-profiles of heavy metals in the columns packing, at the end of the experiment, demonstrated that the ZVI columns still had excess capacity to remove heavy metals, while the capacity of the limestone control column was approaching saturation. The ZVI provided conditions that enhanced sulfate reduction and generated alkalinity. Collectively, the results demonstrate an innovative passive ARD remediation process using ZVI as sole electron-donor. Copyright © 2016 Elsevier B.V. All rights reserved.

Nano-composites for water remediation: a review.

PubMed

Tesh, Sarah J; Scott, Thomas B

2014-09-17

As global populations continue to increase, the pressure on water supplies will inevitably intensify. Consequently the international need for more efficient and cost effective water remediation technologies will also rise. The introduction of nano-technology into the industry may represent a significant advancement and zero-valent iron nano-particles (INPs) have been thoroughly studied for potential remediation applications. However, the application of water dispersed INP suspensions is limited and somewhat contentious on the grounds of safety, whilst INP reaction mechanisms, transport properties and ecotoxicity are areas still under investigation. Theoretically, the development of nano-composites containing INPs to overcome these issues provides the logical next step for developing nano-materials that are better suited to wide application across the water industry. This review provides an overview of the range of static, bulk nano-composites containing INPs being developed, whilst highlighting the limitations of individual solutions, overall classes of technology, and lack of comparative testing for nano-composites. The review discusses what further developments are needed to optimize nano-composite water remediation systems to subsequently achieve commercial maturity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) from wastewaters by zero-valent iron (ZVI): predominant removal mechanism for effective SDBS removal.

PubMed

Takayanagi, Akari; Kobayashi, Maki; Kawase, Yoshinori

2017-03-01

Mechanisms for removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in wastewaters by zero-valent iron (ZVI) were systematically examined. The contributions of four removal mechanisms, i.e., reductive degradation, oxidative degradation, adsorption, and precipitation, changed significantly with solution pH were quantified and the effective removal of SDBS by ZVI was found to be attributed to the adsorption capability of iron oxides/hydroxides on ZVI surface at nearly neutral pH instead of the degradation at acidic condition. The fastest SDBS removal rate and the maximum TOC (total organic carbon) removal efficiency were obtained at pH 6.0. The maximum TOC removal at pH 6.0 was 77.8%, and the contributions of degradation, precipitation, and adsorption to TOC removal were 4.6, 14.9, and 58.3%, respectively. At pH 3.0, which is an optimal pH for oxidative degradation by the Fenton reaction, the TOC removal was only 9.8% and the contributions of degradation, precipitation, and adsorption to TOC removal were 2.3, 4.6, and 2.9%, respectively. The electrostatic attraction between dodecyl benzene sulfate anion and the iron oxide/hydroxide layer controlled the TOC removal of SDBS. The kinetic model based on the Langmuir-Hinshelwood/Eley-Rideal approach could successfully describe the experimental results for SDBS removal by ZVI with the averaged correlation coefficient of 0.994. ZVI was found to be an efficient material toward the removal of anionic surfactant at nearly neutral pH under the oxic condition.

Nanoscale zerovalent iron-mediated degradation of DDT in soil.

PubMed

Han, Yuling; Shi, Nan; Wang, Huifang; Pan, Xiong; Fang, Hua; Yu, Yunlong

2016-04-01

Nanoscale zerovalent iron (nZVI)-mediated degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) was investigated in a spiked soil under different conditions (iron sources, iron dosage, soil moisture, temperature, and soil types) and DDT-contaminated field. The degradation efficiency of p,p'-DDT by nZVI and nZVI coated with sodium oleate (SO-nZVI) was much higher than that by nZVI coated with polyimide (PI-nZVI). The rapid degradation of p,p'-DDT by nZVI only occurred in flooded soil. The degradation half-life of p,p'-DDT decreased significantly from 58.3 to 27.6 h with nZVI dosage from 0.5 to 2.0% and from 46.5 to 32.0 h with temperature from 15 to 35 °C. The degradation efficiency of p,p'-DDT by nZVI differed in Jinhua (JH), Jiaxing (JX), Xiaoshan (XS), Huajiachi (HJC), and Heilongjiang (HLJ) soils. A good correlation was found between the degradation half-life of p,p'-DDT and multiple soil properties. The probable nZVI-mediated degradation pathway of p,p'-DDT in soil was proposed as DDT → DDD/DDE → DDNS → DDOH based on the metabolites identified by GC-MS. The in situ degradation efficiency of residual DDTs in a contaminated field was profoundly enhanced by the addition of nZVI as compared to the control. It is concluded that nZVI might be an efficient agent for the remediation of DDT-contaminated soil under anaerobic environment.

Use of agar agar stabilized milled zero-valent iron particles for in situ groundwater remediation

NASA Astrophysics Data System (ADS)

Schmid, Doris; Velimirović, Milica; Wagner, Stephan; Micić Batka, Vesna; von der Kammer, Frank; Hofmann, Thilo

2015-04-01

A major obstacle for use of nanoscale zero-valent iron (nZVI) particles as a nontoxic material for effective in situ degradation of chlorinated aliphatic hydrocarbons (CAHs) is the high production cost. For that reason, submicro-scale milled zero-valent iron particles were recently developed (milled ZVI, UVR-FIA, Germany) by grinding macroscopic raw materials of elementary iron as a cheaper alternative to products produced by solid-state reduction. However, milled ZVI particles tend to aggregate and due to the rather large particle size (d50= 11.9 µm) also rapidly sediment. To prevent aggregation and consequently sedimentation of milled ZVI particles and therefore improve the mobility after in situ application, the use of a stabilizer is considered in literature as a most promising option. In this study, milled ZVI particles (1 g L-1 of particle concentration) were stabilized by environmentally friendly polymer agar agar (>0.5 g L-1), which had a positive impact on the milled ZVI stability. Sedimentation rate was significantly decreased by increasing the suspension viscosity. Column transport experiments were performed for bare and agar agar stabilized milled ZVI particles in commercially available fine grained quartz sand (DORSILIT® Nr.8, Gebrüder Dorfner GmbH Co, Germany) and different porous media collected from brownfields. The experiments were carried out under field relevant injection conditions of 100 m d-1. The maximal travel distance (LT) of less than 10 cm was determined for non-stabilized suspension in fine grained quartz sand, while agar agar (1 g L-1) stabilized milled ZVI suspension revealed LT of 12 m. Similar results were observed for porous media from brownfields showing that mobility of agar agar stabilized particle suspensions was significantly improved compared to bare particles. Based on the mobility data, agar agar stabilized milled zero-valent iron particles could be used for in situ application. Finally, lab-scale batch degradation experiments were performed to determine the impact of agar agar on the reactivity of milled ZVI and investigate the apparent corrosion rate of particles by quantifying the hydrogen gas generated by anaerobic corrosion of milled ZVI. The results indicate that agar agar had a positive impact on the milled ZVI stability and mobility, however adverse impact on the reactivity towards trichloroethene (TCE) was observed compared to the non-stabilized material. On the other hand, this study shows that the apparent corrosion rate of non-stabilized and agar agar stabilized milled ZVI particles is in the same order of magnitude. These data indicate that the dechlorination pathway of TCE by agar agar stabilized milled ZVI particles is possibly impacted by blocking of the reactive sites and not hydrogen revealed during particles corrosion. Finally, calculated longevity of the particles based on the apparent corrosion rate is significantly prolonged compared to the longevity of the nZVI particles reported in previous studies. This research receives funding from the European Union's Seventh Framework Programme FP7/2007-2013 under grant agreement n°309517.

Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

NASA Astrophysics Data System (ADS)

Strutz, Tessa J.; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

2016-08-01

Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2 m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1 m/h and elemental iron input concentrations (Fe0in) of 0.6, 10, and 17 g/L. Concentrations of Fe0 in the sand were determined by magnetic susceptibility scans, which provide detailed Fe0 distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe0 concentrations of about 14-18 g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a significant role for attachment, mainly at lower injection velocities. Since the injection of fluids at real sites leads to descending flow velocities with increasing radial distance from the injection point, the simulation of particle transport requires accounting for all deposition processes mentioned above. Thus, the derived mean parameter set can be used as a basis for quantitative and predictive simulations of particle distributions and clogging effects at both lab and field scale. Since decreases in K can change the flow system, which may have positive as well as negative implications for the in situ remediation technology at a contaminated site, a reliable simulation is thus of great importance for NZVI injection and prediction.

IN-SITU REMEDIATION OF ARSENIC IN SIMULATED GROUNDWATER USING ZEROVALENT IRON: LABORATORY COLUMN TESTS ON COMBINED EFFECTS OF PHOSPHATE AND SILICATE

EPA Science Inventory

We performed three column tests to study the behavior of permeable reactive barrier (PRB) materials to remove arsenic under dynamic flow conditions in the absence, as well as in the presence, of added phosphate and silicate. The column consisted of a 10.3-cm depth of 50 : 50 (w :...

Use of Nanoscale Emulsified Zero-valent Iron to Treat a Chlorinated Solvent Source Zone at Site 45, Marine Corp Recruit Depot, Parris Island, South Carolina

EPA Science Inventory

This document summarizes the research activities currently underway at the Solid Waste Management Unit 45 (Site 45), Marine Corps Recruit Depot, Parris Island, South Carolina. A pilot field test was initiated in 2005 at this site to evaluate the effectiveness of nanoscale emulsif...

In Situ Wetland Restoration Demonstration

DTIC Science & Technology

2014-07-28

products, charcoal, zero-valent iron, sulfur-infused AC, and/or zeolite (USEPA, 1994; USEPA, 1997; Renholds, 1998; Reible, 2004; Barth and Reible, 2008...activated carbon, zeolites , or other sequestration agents can be effectively delivered to the hydric soils, then toxicity, mobility, and...Organoclays, zeolites , and activated carbon have been used extensively for the treatment of water and soil contamination (McDonald et al., 2004

Surface coating with Ca(OH)2 for improvement of the transport of nanoscale zero-valent iron (nZVI) in porous media.

PubMed

Wei, Cai-jie; Li, Xiao-yan

2013-01-01

A novel thermal deposition method was developed to coat Ca(OH)2 on the surface of nanoscale zero-valent iron (nZVI). The nZVI particles with the Ca(OH)2 coating layer, nZVI/Ca(OH)2, had a clear core-shell structure based on the transmission electron microscopy observations, and the Ca(OH)2 shell was identified as an amorphous phase. The Ca(OH)2 coating shell would not only function as an effective protection layer for nZVI but also improve the mobility of nZVI in porous media for its use in environmental decontamination. A 10% Ca/Fe mass ratio was found to result in a proper thickness of the Ca(OH)2 shell on the nZVI surface. Based on the filtration tests in sand columns, the Ca(OH)2-based surface coating could greatly improve the mobility and transport of nZVI particles in porous media. In addition, batch experiments were conducted to evaluate the reactivity of Ca(OH)2-coated nZVI particles for the reduction of Cr(VI) and its removal from water.

Simultaneous addition of zero-valent iron and activated carbon on enhanced mesophilic anaerobic digestion of waste-activated sludge.

PubMed

Wang, Tongyu; Qin, Yujie; Cao, Yan; Han, Bin; Ren, Junyi

2017-10-01

The performance of biogas generation and sludge degradation was studied under different zero-valent iron/activated carbon (ZVI/AC) ratios in detail in mesophilic anaerobic digestion of sludge. A good enhancement of methane production was obtained at the 10:1 ZVI/AC ratio, and the cumulative methane production was 132.1 mL/g VS, 37.6% higher than the blank. The methane content at the 10:1 ZVI/AC ratio reached 68.8%, which was higher than the blank (55.2%) and the sludge-added AC alone (59.6%). For sludge degradation, the removal efficiencies of total chemical oxygen demand (TCOD), proteins, and polysaccharides were all the highest at the 10:1 ZVI/AC ratio. The concentration of available phosphorus (AP) decreased after anaerobic digestion process. On the other hand, the concentrations of available nitrogen (AN) and available potassium (AK) increased after the anaerobic digestion process and showed a gradually decreasing trend with increasing ZVI/AC ratio. The concentrations of AN and AK were 2303.1-4200.3 and 274.7-388.3 mg/kg, showing a potential for land utilization.

Wheat straw biochar-supported nanoscale zerovalent iron for removal of trichloroethylene from groundwater

PubMed Central

Li, Hui; Chen, Ya Qin; Chen, Shuai; Wang, Xiao Li; Guo, Shu; Qiu, Yue Feng; Liu, Yong Di; Duan, Xiao Li; Yu, Yun Jiang

2017-01-01

This study synthesized the wheat straw biochar-supported nanoscale zerovalent iron (BC-nZVI) via in-situ reduction with NaBH4 and biochar pyrolyzed at 600°C. Wheat straw biochar, as a carrier, significantly enhanced the removal of trichloroethylene (TCE) by nZVI. The pseudo-first-order rate constant of TCE removal by BC-nZVI (1.079 h−1) within 260 min was 1.4 times higher and 539.5 times higher than that of biochar and nZVI, respectively. TCE was 79% dechlorinated by BC-nZVI within 15 h, but only 11% dechlorinated by unsupported nZVI, and no TCE dechlorination occurred with unmodified biochar. Weakly acidic solution (pH 5.7–6.8) significantly enhanced the dechlorination of TCE. Chloride enhanced the removal of TCE, while SO42−, HCO3− and NO3− all inhibited it. Humic acid (HA) inhibited BC-nZVI reactivity, but the inhibition decreased slightly as the concentration of HA increased from 40 mg∙L-1 to 80 mg∙L-1, which was due to the electron shutting by HA aggregates. Results suggest that BC-nZVI was promising for remediation of TCE contaminated groundwater. PMID:28264061

Wheat straw biochar-supported nanoscale zerovalent iron for removal of trichloroethylene from groundwater.

PubMed

Li, Hui; Chen, Ya Qin; Chen, Shuai; Wang, Xiao Li; Guo, Shu; Qiu, Yue Feng; Liu, Yong Di; Duan, Xiao Li; Yu, Yun Jiang

2017-01-01

This study synthesized the wheat straw biochar-supported nanoscale zerovalent iron (BC-nZVI) via in-situ reduction with NaBH4 and biochar pyrolyzed at 600°C. Wheat straw biochar, as a carrier, significantly enhanced the removal of trichloroethylene (TCE) by nZVI. The pseudo-first-order rate constant of TCE removal by BC-nZVI (1.079 h-1) within 260 min was 1.4 times higher and 539.5 times higher than that of biochar and nZVI, respectively. TCE was 79% dechlorinated by BC-nZVI within 15 h, but only 11% dechlorinated by unsupported nZVI, and no TCE dechlorination occurred with unmodified biochar. Weakly acidic solution (pH 5.7-6.8) significantly enhanced the dechlorination of TCE. Chloride enhanced the removal of TCE, while SO42-, HCO3- and NO3- all inhibited it. Humic acid (HA) inhibited BC-nZVI reactivity, but the inhibition decreased slightly as the concentration of HA increased from 40 mg∙L-1 to 80 mg∙L-1, which was due to the electron shutting by HA aggregates. Results suggest that BC-nZVI was promising for remediation of TCE contaminated groundwater.

Long-Term Field Study of Microbial Community and Dechlorinating Activity Following Carboxymethyl Cellulose-Stabilized Nanoscale Zero-Valent Iron Injection.

PubMed

Kocur, Chris M D; Lomheim, Line; Molenda, Olivia; Weber, Kela P; Austrins, Leanne M; Sleep, Brent E; Boparai, Hardiljeet K; Edwards, Elizabeth A; O'Carroll, Denis M

2016-07-19

Nanoscale zerovalent iron (nZVI) is an emerging technology for the remediation of contaminated sites. However, there are concerns related to the impact of nZVI on in situ microbial communities. In this study, the microbial community composition at a contaminated site was monitored over two years following the injection of nZVI stabilized with carboxymethyl cellulose (nZVI-CMC). Enhanced dechlorination of chlorinated ethenes to nontoxic ethene was observed long after the expected nZVI oxidation. The abundance of Dehalococcoides (Dhc) and vinyl chloride reductase (vcrA) genes, monitored using qPCR, increased by over an order of magnitude in nZVI-CMC-impacted wells. The entire microbial community was tracked using 16S rRNA gene amplicon pyrosequencing. Following nZVI-CMC injection, a clear shift in microbial community was observed, with most notable increases in the dechlorinating genera Dehalococcoides and Dehalogenimonas. This study suggests that coupled abiotic degradation (i.e., from reaction with nZVI) and biotic degradation fueled by CMC led to the long-term degradation of chlorinated ethenes at this field site. Furthermore, nZVI-CMC addition stimulated dehalogenator growth (e.g., Dehalococcoides) and biotic degradation of chlorinated ethenes.

Environmental Risks of Nano Zerovalent Iron for Arsenate Remediation: Impacts on Cytosolic Levels of Inorganic Phosphate and MgATP2- in Arabidopsis thaliana.

PubMed

Zhang, Weilan; Lo, Irene M C; Hu, Liming; Voon, Chia Pao; Lim, Boon Leong; Versaw, Wayne K

2018-04-03

The use of nano zerovalent iron (nZVI) for arsenate (As(V)) remediation has proven effective, but full-scale injection of nZVI into the subsurface has aroused serious concerns for associated environmental risks. This study evaluated the efficacy of nZVI treatment for arsenate remediation and its potential hazards to plants using Arabidopsis thaliana grown in a hydroponic system. Biosensors for inorganic phosphate (Pi) and MgATP 2- were used to monitor in vivo Pi and MgATP 2- levels in plant cells. The results showed that nZVI could remove As(V) from growth media, decrease As uptake by plants, and mitigate As(V) toxicity to plants. However, excess nZVI could cause Pi starvation in plants leading to detrimental effects on plant growth. Due to the competitive adsorption of As(V) and Pi on nZVI, removing As(V) via nZVI treatment at an upstream site could relieve downstream plants from As(V) toxicity and Pi deprivation, in which case 100 mg/L of nZVI was the optimal dosage for remediation of As(V) at a concentration around 16.13 mg/L.

Effects of nitrate on the treatment of lead contaminated groundwater by nanoscale zerovalent iron.

PubMed

Su, Yiming; Adeleye, Adeyemi S; Zhou, Xuefei; Dai, Chaomeng; Zhang, Weixian; Keller, Arturo A; Zhang, Yalei

2014-09-15

Nanoscale zerovalent iron (nZVI) is efficient for removing Pb(2+) and nitrate from water. However, the influence of nitrate, a common groundwater anion, on Pb(2+) removal by nZVI is not well understood. In this study, we showed that under excess Fe(0) conditions (molar ratio of Fe(0)/nitrate>4), Pb(2+) ions were immobilized more quickly (<5 min) than in nitrate-free systems (∼ 15 min) due to increasing pH. With nitrate in excess (molar ratio of Fe(0)/nitrate<4), nitrate stimulated the formation of crystal PbxFe3-xO4 (ferrite), which provided additional Pb(2+) removal. However, ∼ 7% of immobilized Pb(2+) ions were released into aqueous phase within 2h due to ferrite deformation. Oxidation-reduction potential (ORP) values below -600 mV correlated with excess Fe(0) conditions (complete Pb(2+) immobilization), while ORP values ≥-475 mV characterized excess nitrate conditions (ferrite process and Pb(2+) release occurrence). This study indicates that ORP monitoring is important for proper management of nZVI-based remediation in the subsurface to avoid lead remobilization in the presence of nitrate. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhancement of stability of various nZVI suspensions used in groundwater remediation with environmentally friendly organic stabilizers

NASA Astrophysics Data System (ADS)

Schmid, Doris; Wagner, Stephan; Velimirović, Milica; Laumann, Susanne; Micić, Vesna; Hofmann, Thilo

2014-05-01

The use of nanoscale zero-valent iron (nZVI) particles for in situ remediation of polluted soil and groundwater has been shown as one of the most promising techniques [1]. The success of this technology depends on the mobility, reactivity, and longevity of nZVI particles. The mobility of nZVI particles depends on the properties of the single particles, stability of the particle suspension, and the aquifer material [1,2]. In order to enhance the mobility of nZVI, the mobility-decisive properties of the nZVI particles in suspension such as concentration, size distribution, surface charge, and sedimentation rate have to be investigated and optimized. Previous studies showed that pristine nZVI particles aggregate rapidly in water, reducing the particles radius of influence after injection [3]. In order to prevent aggregation and sedimentation of the nZVI particles, and consequently improve the stability of nZVI suspension and therefore the mobility of the nZVI particles, surface stabilizers can be used to provide electrostatic repulsion and steric or electrosteric stabilization [3,4]. The objective of this lab-scale study is to investigate the potential for enhancing the stability of different nZVI suspensions by means of environmentally friendly organic stabilizers, including carboxymethyl cellulose, pectin, alginate, xanthan, and guar gum. The different nZVI particles used included pristine and polyacrylic acid-coated nZVI particles provided in suspension (Nanofer 25 and Nanofer 25S, respectively, NANOIRON s.r.o., Czech Republic), air-stable nZVI particles (Nanofer Star, (NANOIRON s.r.o., Czech Republic), and milled iron flakes (UVR-FIA, Germany). In order to study the enhancement of nZVI stability (1 g L-1 total iron) different concentrations of organic stabilizers (1-20 wt.%) were applied in these nZVI suspensions. Each nZVI suspension was freshly prepared and treated for 10 minutes with Ultra-Turrax (15 000 rpm) and 10 minutes ultrasonic bath prior to characterization. Suspensions were characterized in terms of particle size distribution (Eyetech, Ambivalue; Malvern Mastersizer 2000), surface charge (Malvern ZetaSizer Nano), pH, EC, zero-valent iron content (H2 production after acid digestion), total iron content (ICP-OES), and sedimentation rate (TurbiScan LAB EXPERT). The results of the first set of experiments carried out with a pristine suspension of milled iron flakes (1 g L-1 total iron) show that the sedimentation rate of the suspension decreased by a factor two when stabilized by a 20 wt.% solution of carboxymethyl cellulose. This indicates that carboxymethyl cellulose was able to increase the stability of the suspension of milled iron flakes. Moreover, the surface charge of milled iron particles became more negatively charged once carboxymethyl cellulose was applied as a stabilizer, confirming an increased potential for milled iron flakes repulsion in the presence of carboxymethyl cellulose. Nevertheless, the size of these particles in the presence of carboxymethyl cellulose did not change for more than 5% compared to the particle size of pristine suspension of milled iron flakes. On the basis of the preliminary results from the sedimentation tests column reactors will be designed in order to compare the transport distances of milled iron flakes and other selected nZVI particles. This research receives funding from the European Union's Seventh Framework Programme FP7/2007-2013 under grant agreement n°309517. [1] O'Carroll et al. (2013): Advances in Water Resources 51(0): 104-122. [2] Laumann et al. (2013): Environmental Pollutant 179: 53-60. [3] Phenrat et al. (2007): ES&T 41(1): 284-290. [4] Phenrat et al. (2008): Journal of Nanoparticle Research 10(5): 795-814.

Effect of groundwater geochemistry on pentachlorophenol remediation by smectite-templated nanosized Pd0/Fe0.

PubMed

Jia, Hanzhong; Gu, Cheng; Li, Hui; Fan, Xiaoyun; Li, Shouzhu; Wang, Chuanyi

2012-09-01

Zero-valent iron holds great promise in treating groundwater, and its reactivity and efficacy depend on many surrounding factors. In the present work, the effects of solution chemistry such as pH, humic acid (HA), and inorganic ions on pentachlorophenol (PCP) dechlorination by smectite-templated Pd(0)/Fe(0) were systematically studied. Smectite-templated Pd(0)/Fe(0) was prepared by saturating the negatively charged sites of smectite clay with Fe(III) and a small amount of Pd(II), followed by borohydride reduction to convert Fe(III) and Pd(II) into zero-valent metal clusters. Batch experiments were conducted to investigate the effects of water chemistry on PCP remediation. The PCP dechlorination rate critically depends on the reaction pH over the range 6.0~10.0; the rate constant (k (obs)) increases with decreasing the reaction pH value. Also, the PCP remediation is inhibited by HA, which can be attributed to the electron competition of HA with H(+). In addition, the reduction of PCP can be accelerated by various anions, following the order: Cl(-) > HCO (3) (-) > SO (4) (2-) ~no anion. In the case of cations, Ca(2+) and Mg(2+) (10 mM) decrease the dechlorination rate to 0.7959 and 0.7798 from 1.315 h(-1), respectively. After introducing HA into the reaction systems with cations or/and anions, the dechlorination rates are similar to that containing HA alone. This study reveals that low pH and the presence of some anions such as Cl(-) facilitate the PCP dechlorination and induce the rapid consumption of nanosized zero-valent iron simultaneously. However, the dechlorination rate is no longer correlated to the inhibitory or accelerating effects by cations and anions in the presence of 10 mg/L HA.

Nanoscale zerovalent iron (nZVI) at environmentally relevant concentrations induced multigenerational reproductive toxicity in Caenorhabditis elegans.

PubMed

Yang, Ying-Fei; Chen, Pei-Jen; Liao, Vivian Hsiu-Chuan

2016-05-01

Nanoscale zerovalent iron (nZVI) is widely used with large scale for environmental remediation for in situ or ex situ applications. The potential impact of nZVI on biota at environmentally relevant concentrations needs to be elucidated. In this study, the reproductive toxicities of three irons species: carboxymethyl cellulose (CMC)-stabilized nZVI, nanoscale iron oxide (nFe3O4), and ferrous ion (Fe(II)aq) in the soil-dwelling nematode Caenorhabditis elegans were examined. In addition, the generational transfer of reproductive toxicity of CMC-nZVI on C. elegans was investigated. The results showed that CMC-nZVI, nFe3O4, and Fe(II)aq did not cause significant mortality after 24 h exposure at the examined concentrations. Reproductive toxicity assays revealed that CMC-nZVI, nFe3O4, and Fe(II)aq significantly decreased offsprings in parental generation (F0) in accompany with the increased intracellular reactive oxygen species (ROS). Furthermore, the reproductive toxicity of CMC-nZVI at environmentally relevant concentrations was transferrable from the F0 to the F1 and F2 generations, but then recovered in the F3 and F4 generations. Further evidence showed that total irons were accumulated in the F0 and F1 generations of C. elegans after CMC-nZVI parental exposure. This study demonstrated that environmentally relevant concentrations of CMC-nZVI induced multigenerational reproductive toxicity which can be ascribed to its high production of ROS in F0 generation, toxicity of Fe(II)aq, and iron accumulation in C. elegans. Since nZVI is widely used for environmental remediation, considering the multigenerational toxicity, this study thus implicates a potential environmental risk of nZVI-induced nanotoxicity in the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

NASA Astrophysics Data System (ADS)

Xi, Dong; Luo, XiaoPing; Lu, QiangHua; Yao, KaiLun; Liu, ZuLi; Ning, Qin

2008-03-01

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method.

Deposition of platinum nanoparticles on carbon nanotubes by supercritical fluid method.

PubMed

Yen, Clive H; Cui, Xiaoli; Pan, Horng-Bin; Wang, Shaofen; Lin, Yuehe; Wai, Chien M

2005-11-01

Carbon nanotube-supported platinum nanoparticles with a 5-15 nm diameter size range can be synthesized by hydrogen reduction of platinum(ll) acetylacetonate in methanol modified supercritical carbon dioxide. X-ray photoelectron spectroscopy and X-ray diffraction spectra indicate that the carbon nanotubes contain zero-valent platinum metal and high-resolution transmission electron microscopy images show that the visible lattice fringes of platinum nanoparticles are crystallites. Carbon nanotubes synthesized with 25% by weight of platinum nanoparticles exhibit a higher activity for hydrogenation of benzene compared with a commercial carbon black platinum catalyst. The carbon nanotube-supported platinum nanocatalyst can be reused at least six times for the hydrogenation reaction without losing activity. The carbon nanotube-supported platinum nanoparticles are also highly active for electrochemical oxidation of methanol and for reduction of oxygen suggesting their potential use as a new electrocatalyst for proton exchange membrane fuel cell applications.

Electrolytic Transformation of Hexyhydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) and 2,4,6-Trinitrotoluene (TNT) in Aqueous Solutions

DTIC Science & Technology

2005-08-01

several years (Bunce et al. 1997; de Lima Leite et al. 2003; Panizza and Cerisola 2004). Treatment is achieved by either oxidation (anodic) or reduction...Hexahydro-1,3,5-trinitro- 1,3,5-triazine mineralization by zerovalent iron and mixed anaerobic cultures,” Environ. Sci. Technol. 35, 4341-4346. Panizza

Electrolytic Transformation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) and 2,4,6-Trintrotoluene (TNT) in Aqueous Solutions

DTIC Science & Technology

2005-08-01

several years (Bunce et al. 1997; de Lima Leite et al. 2003; Panizza and Cerisola 2004). Treatment is achieved by either oxidation (anodic) or reduction...Hexahydro-1,3,5-trinitro- 1,3,5-triazine mineralization by zerovalent iron and mixed anaerobic cultures,” Environ. Sci. Technol. 35, 4341-4346. Panizza

Mechanism of enhanced nitrate reduction via micro-electrolysis at the powdered zero-valent iron/activated carbon interface.

PubMed

Luo, Jinghuan; Song, Guangyu; Liu, Jianyong; Qian, Guangren; Xu, Zhi Ping

2014-12-01

Nitrate reduction by zero-valent iron (Fe(0)) powder always works well only at controlled pH lower than 4 due to the formation of iron (hydr)oxides on its surface. Fe(0) powder combined with activated carbon (AC), i.e., Fe(0)/AC micro-electrolysis system, was first introduced to enhance nitrate reduction in aqueous solution. Comparative study was carried out to investigate nitrate reduction by Fe(0)/AC system and Fe(0) under near-neutral conditions, showing that the Fe(0)/AC system successfully reduced nitrate even at initial pH 6 with the reduction efficiency of up to 73%, whereas for Fe(0) only ∼10%. The effect of Fe(0) to AC mass ratio on nitrate reduction efficiency was examined. Easier nitrate reduction was achieved with more contact between Fe(0) and AC as the result of decreasing Fe(0) to AC mass ratio. Ferrous ion and oxidation-reduction potential were measured to understand the mechanism of enhanced nitrate reduction by Fe(0)/AC micro-electrolysis. The results suggest that a relative potential difference drives much more electrons from Fe(0) to AC, thus generating adsorbed atomic hydrogen which makes it possible for nitrate to be reduced at near-neural pH. Fe(0)/AC micro-electrolysis thus presents a great potential for practical application in nitrate wastewater treatment without excessive pH adjustment. Copyright © 2014 Elsevier Inc. All rights reserved.

Removal of nitrobenzene by immobilized nanoscale zero-valent iron: Effect of clay support and efficiency optimization

NASA Astrophysics Data System (ADS)

Li, Xiaoguang; Zhao, Ying; Xi, Beidou; Mao, Xuhui; Gong, Bin; Li, Rui; Peng, Xing; Liu, Hongliang

2016-05-01

In this study, natural clays were used as the support for nanoscale zero-valent iron (nZVI) to fulfill affordable and efficient decontamination materials. In comparison with the kaolinite (K) and montmorillonite (M) supported nZVI materials (K-nZVI and M-nZVI), Hangjin clay supported nZVI (HJ-nZVI) exhibited the best performance for nitrobenzene (NB) removal because of its favorable characteristics, such as higher specific surface area (SSA, 82.0 m2 g-1), larger pore volume (0.1198 cm3 g-1) and bigger average pore diameter (6.2 nm). The NB removal efficiency achieved by HJ-nZVI (93.2 ± 2.8%) was much higher than these achieved by HJ clay alone (38.2 ± 2.3%), nZVI alone (52.3 ± 2.5%) and by the combined use of nZVI and HJ clay (70.2 ± 1.3%). The superior performance of HJ-nZVI was associated with three aspects: the even distribution of nZVIs onto HJ clay, higher payload efficiency of nZVIs and the stronger adsorption capability of HJ clay support. Higher SSA, larger pore volume, favorable cation exchange capacity and structural negative charges all facilitated the payload of iron onto HJ clay. The adsorption process accelerated the reduction via increasing the local concentration of aqueous NB. The high efficiency of HJ-nZVI for decontamination warranted its promising prospect in remediation applications.

Nanoscale zero-valent iron (nZVI) for the treatment of concentrated Cu(II) wastewater: a field demonstration.

PubMed

Li, Shaolin; Wang, Wei; Yan, Weile; Zhang, Wei-xian

2014-03-01

A field demonstration was conducted to assess the feasibility of nanoscale zero-valent iron (nZVI) for the treatment of wastewater containing high levels of Cu(II). Pilot tests were performed at a printed-circuit-board manufacturing plant, treating 250,000 L of wastewater containing 70 mg L(-1) Cu(II) with a total of 55 kg of nZVI. A completely mixed reactor of 1,600 L was operated continuously with flow rates ranging from 1000 to 2500 L h(-1). The average Cu(II) removal efficiency was greater than 96% with 0.20 g L(-1) nZVI and a hydraulic retention time of 100 min. The nZVI reactor achieved a remarkably high volumetric loading rate of 1876 g Cu per m(3) per day for Cu(II) removal, surpassing the loading rates of conventional technologies by more than one order of magnitude. The average removal capacity of nZVI for Cu(II) was 0.343 g Cu per gram of Fe. The Cu(II) removal efficiency can be reliably regulated by the solution Eh, which in turn is a function of nZVI input and hydraulic retention time. The ease of separation and recycling of nZVI contribute to process up-scalability and cost effectiveness. Cu(II) was reduced to metallic copper and cuprite (Cu2O). The end product is a valuable composite of iron and copper (∼20-25%), which can partially offset the treatment costs.

Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.

PubMed

Qin, Hejie; Li, Jinxiang; Yang, Hongyi; Pan, Bingcai; Zhang, Weiming; Guan, Xiaohong

2017-05-02

Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe 0 was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe 0 core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe 0 to surface-located Se(VI).

A 2D tank test on remediation of nitrobenzene-contaminated aquifer using in-situ reactive zone with emulsified nanoscale zero-valent iron.

PubMed

Dong, Jun; Dong, Yang; Wen, Chunyu; Gao, Song; Ren, Liming; Bao, Qiburi

2018-05-15

Nitrobenzene (NB) is one of the most challenging pollutants for groundwater remediation due to its great harm and recalcitrance. Emulsified nanoscale zero-valent iron (EZVI) is considered as a promising agent for in-situ remediation of contaminated groundwater for its high reactivity, good durability and low cost. In this paper, 2D tank experiment was conducted to evaluate the effectiveness of enhanced remediation of NB-contaminated groundwater with EZVI. 9 L of EZVI solution was injected into aquifer to establish in-situ reactive zone (IRZ) before 40 d of NB contamination. Results indicate that injection of EZVI leads to 90% reduction of total NB, which is mainly converted to aniline (AN). NB concentration decreases along the flow path in the tank. Fe 2+ is generated from Fe 0 oxidation. Significant acetate and bicarbonate are released due to emulsified oil decomposition during the whole operation time. Groundwater pH maintains in neutral value (6.6-8.2) owing to the balance between organic acids and OH - released after iron oxidation. Drastic decrease of ORP and DO indicates the transformation from oxidizing to reducing condition, leading to the reduction of oxidative species (e.g. sulfate, nitrate) in subsurface. Calculation of reducing equivalents suggests that microbial breakdown of emulsified oil provides more electrons than Fe 0 oxidation does to the system. Both biotic and abiotic processes are involved in the enhanced degradation of NB. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biochar composites with nano zerovalent iron and eggshell powder for nitrate removal from aqueous solution with coexisting chloride ions.

PubMed

Ahmad, Munir; Ahmad, Mahtab; Usman, Adel R A; Al-Faraj, Abdullah S; Abduljabbar, Adel S; Al-Wabel, Mohammad I

2017-09-18

Biochar (BC) was produced from date palm tree leaves and its composites were prepared with nano zerovalent iron (nZVI-BC) and hen eggshell powder (EP-BC). The produced BC and its composites were characterized by SEM, XRD, BET, and FTIR for surface structural, mineralogical, and chemical groups and tested for their efficiency for nitrate removal from aqueous solutions in the presence and absence of chloride ions. The incidence of graphene and nano zerovalent iron (Fe 0 ) in the nZVI-BC composite was confirmed by XRD. The nZVI-BC composite possessed highest surface area (220.92 m 2  g -1 ), carbon (80.55%), nitrogen (3.78%), and hydrogen (11.09%) contents compared to other materials. Nitrate sorption data was fitted well to the Langmuir (R 2  = 0.93-0.98) and Freundlich (R 2  = 0.90-0.99) isotherms. The sorption kinetics was adequately explained by the pseudo-second-order, power function, and Elovich models. The nZVI-BC composite showed highest Langmuir predicted sorption capacity (148.10 mg g -1 ) followed by EP-BC composite (72.77 mg g -1 ). In addition to the high surface area, the higher nitrate removal capacity of nZVI-BC composite could be attributed to the combination of two processes, i.e., chemisorption (outer-sphere complexation) and reduction of nitrate to ammonia or nitrogen by Fe 0 . The appearance of Fe-O stretching and N-H bonds in post-sorption FTIR spectra of nZVI-BC composite suggested the occurrence of redox reaction and formation of Fe compound with N, such as ferric nitrate (Fe(NO 3 ) 3 ·9H 2 O). Coexistence of chloride ions negatively influenced the nitrate sorption. The decrease in nitrate sorption with increasing chloride ion concentration was observed, which could be due to the competition of free active sites on the sorbents between nitrate and chloride ions. The nZVI-BC composite exhibited higher nitrate removal efficiency compared to other materials even in the presence of highest concentration (100 mg L -1 ) of coexisting chloride ion.

Synthesis and characterization of dextran-coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

2018-03-01

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

Zero-valent iron treatment of dark brown colored coffee effluent: Contributions of a core-shell structure to pollutant removals.

PubMed

Tomizawa, Mayuka; Kurosu, Shunji; Kobayashi, Maki; Kawase, Yoshinori

2016-12-01

The decolorization and total organic carbon (TOC) removal of dark brown colored coffee effluent by zero-valent iron (ZVI) have been systematically examined with solution pH of 3.0, 4.0, 6.0 and 8.0 under oxic and anoxic conditions. The optimal decolorization and TOC removal were obtained at pH 8.0 with oxic condition. The maximum efficiencies of decolorization and TOC removal were 92.6 and 60.2%, respectively. ZVI presented potential properties for pollutant removal at nearly neutral pH because of its core-shell structure in which shell or iron oxide/hydroxide layer on ZVI surface dominated the decolorization and TOC removal of coffee effluent. To elucidate the contribution of the core-shell structure to removals of color and TOC at the optimal condition, the characterization of ZVI surface by scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) was conducted. It was confirmed that the core-shell structure was formed and the shell on ZVI particulate surface and the precipitates formed during the course of ZVI treatment consisted of iron oxides and hydroxides. They were significantly responsible for decolorization and TOC removal of coffee effluent via adsorption to shell on ZVI surface and inclusion into the precipitates rather than the oxidative degradation by OH radicals and the reduction by emitted electrons. The presence of dissolved oxygen (DO) enhanced the formation of the core-shell structure and as a result improved the efficiency of ZVI treatment for the removal of colored components in coffee effluents. ZVI was found to be an efficient material toward the treatment of coffee effluents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pressure-controlled injection of guar gum stabilized microscale zerovalent iron for groundwater remediation.

PubMed

Luna, M; Gastone, F; Tosco, T; Sethi, R; Velimirovic, M; Gemoets, J; Muyshondt, R; Sapion, H; Klaas, N; Bastiaens, L

2015-10-01

The paper reports a pilot injection test of microsized zerovalent iron (mZVI) dispersed in a guar gum shear thinning solution. The test was performed in the framework of the EU research project AQUAREHAB in a site in Belgium contaminated by chlorinated aliphatic hydrocarbons (CAHs). The field application was aimed to overcome those critical aspects which hinder mZVI field injection, mainly due to the colloidal instability of ZVI-based suspensions. The iron slurry properties (iron particles size and concentration, polymeric stabilizer type and concentration, slurry viscosity) were designed in the laboratory based on several tests (reactivity tests towards contaminants, sedimentation tests and rheological measurements). The particles were delivered into the aquifer through an injection well specifically designed for controlled-pressure delivery (approximately 10 bars). The well characteristics and the critical pressure of the aquifer (i.e. the injection pressure above which fracturing occurs) were assessed via two innovative injection step rate tests, one performed with water and the other one with guar gum. Based on laboratory and field preliminary tests, a flow regime at the threshold between permeation and preferential flow was selected for mZVI delivery, as a compromise between the desired homogeneous distribution of the mZVI around the injection point (ensured by permeation flow) and the fast and effective injection of the slurry (guaranteed by high discharge rates and injection pressure, resulting in the generation of preferential flow paths). A monitoring setup was designed and installed for the real-time monitoring of relevant parameters during injection, and for a fast determination of the spatial mZVI distribution after injection via non-invasive magnetic susceptibility measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

Calcium hydroxide coating on highly reactive nanoscale zero-valent iron for in situ remediation application.

PubMed

Wei, Cai-Jie; Xie, Yue-Feng; Wang, Xiao-Mao; Li, Xiao-Yan

2018-05-23

Nano scale zero-valent iron (nZVI), a promising engineering technology for in situ remediation, has been greatly limited by quick self-corrosion and low mobility in porous media. Highly reactive nZVI particles produced from the borohydride reduction method were enclosed in a releasable Ca(OH) 2 layer by the chemical deposition method. The amount of Ca(OH) 2 coated on nZVI surface were well controlled by the precursor dosage. At moderate Ca(OH) 2 dosage (R Ca/TFe  = 0.25) condition, the increment of Fe 0 content for the obtained nZVI/Ca-0.25 sample was observed. The interfacial reactions between the iron oxide shell and the Ca(OH) 2 saturated environment were delicately elucidated by the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) spectrum. And the coverage of Ca(OH) 2 shell on spherical nZVI surface was found more complete and uniform for the nZVI/Ca sample obtained from the moderate precursor dosage condition (R Ca/TFe  = 0.25). The Ca(OH) 2 shell before dissolution was demonstrated owning the anti-corrosion capability to slow down the oxidation of Fe 0 core in air, during ethanol storage and in aqueous environment. The mechanism of anti-corrosion capability for nZVI/Ca-0.25 particle was interestingly found to be attributed to the Ca(OH) 2 shell isolation and also be potentially due to the iron oxide shell phase transformation mediated by the outer Ca(OH) 2 shell. An improved trichloroethylene reduction performance was observed for nZVI/Ca-0.25 than bare nZVI. The mobility of nZVI/Ca particles in water-saturated porous media was moderately improved before shell dissolution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Process to Produce Iron Nanoparticle Lunar Dust Simulant Composite

NASA Technical Reports Server (NTRS)

Hung, Ching-cheh; McNatt, Jeremiah

2010-01-01

A document discusses a method for producing nanophase iron lunar dust composite simulant by heating a mixture of carbon black and current lunar simulant types (mixed oxide including iron oxide) at a high temperature to reduce ionic iron into elemental iron. The product is a chemically modified lunar simulant that can be attracted by a magnet, and has a surface layer with an iron concentration that is increased during the reaction. The iron was found to be -iron and Fe3O4 nanoparticles. The simulant produced with this method contains iron nanoparticles not available previously, and they are stable in ambient air. These nanoparticles can be mass-produced simply.

A chemical reduction approach to the synthesis of copper nanoparticles

NASA Astrophysics Data System (ADS)

Khan, Ayesha; Rashid, Audil; Younas, Rafia; Chong, Ren

2016-11-01

Development of improved methods for the synthesis of copper nanoparticles is of high priority for the advancement of material science and technology. Herein, starch-protected zero-valent copper (Cu) nanoparticles have been successfully synthesized by a novel facile route. The method is based on the chemical reduction in aqueous copper salt using ascorbic acid as reducing agent at low temperature (80 °C). X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements were taken to investigate the size, structure and composition of synthesized Cu nanocrystals, respectively. Average crystallite size of Cu nanocrystals calculated from the major diffraction peaks using the Scherrer formula is about 28.73 nm. It is expected that the outcomes of the study take us a step closer toward designing rational strategies for the synthesis of nascent Cu nanoparticles without inert gas protection.

Orange peel + nanostructured zero-valent-iron composite for the removal of hexavalent chromium in water

NASA Astrophysics Data System (ADS)

Olea-Mejía, O.; Cabral-Prieto, A.; Salcedo-Castillo, U.; López-Tellez, G.; Olea-Cardoso, O.; López-Castañares, R.

2017-11-01

In this work we used the Pulsed Plasma in Liquid technique to synthesize zero-valent iron nanostructures. We used a DC Power Source to produce such plasma on water and methanol. The obtained particles were characterized by TEM to determine their shape and size and Mossbauer Spectroscopy to investigate the chemical state of the iron present. We found that 80% of the particles produced in water are composed of metallic iron and when methanol is used 97% of the particles are metallic iron. Once the Fe colloid was formed, orange skin was impregnated with these nanostructures for the removal of in water solution. The Cr(VI) removal experiments were done in a batch system in the presence of the composites at an inicial concentration of 50 ppm of Cr(VI). When using the iron nanostructures supported on the orange peel, the percentage of removal is 100% in the case of nanostructures formed in water and 96% when obtained in methanol.

Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

PubMed Central

Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

2016-01-01

Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them. PMID:27166174

Cryo-Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM)-in-SEM for Bio- and Organo-Mineral Interface Characterization in the Environment.

PubMed

Wille, Guillaume; Hellal, Jennifer; Ollivier, Patrick; Richard, Annie; Burel, Agnes; Jolly, Louis; Crampon, Marc; Michel, Caroline

2017-12-01

Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy). Fluorescent microscopy revealed that nZVI were embedded in the biofilm structure as aggregates but the resolution was insufficient to observe individual nZVI. Cryo-scanning electron microscopy (SEM) observations showed nZVI aggregates close to bacteria, but it was not possible to confirm direct interactions between nZVI and cell membranes. Scanning transmission electron microscopy in the SEM (STEM-in-SEM) showed that nZVI aggregates could enter the biofilm to a depth of 7-11 µm. Bacteria were surrounded by a ring of extracellular polymeric substances (EPS) preventing direct nZVI/membrane interactions. STEM/EDS mapping revealed a co-localization of nZVI aggregates with lectins suggesting a potential role of EPS in nZVI embedding. Thus, the combination of divergent microscopy approaches is a good approach to better understand and characterize biofilm/metal interactions.

Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

NASA Astrophysics Data System (ADS)

Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

2016-05-01

Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

Structural characterization, antibacterial and catalytic effect of iron oxide nanoparticles synthesised using the leaf extract of Cynometra ramiflora

NASA Astrophysics Data System (ADS)

Groiss, Silvia; Selvaraj, Raja; Varadavenkatesan, Thivaharan; Vinayagam, Ramesh

2017-01-01

In the present investigation, the leaf extract of Cynometra ramiflora was used to synthesize iron oxide nanoparticles. Within minutes of adding iron sulphate to the leaf extract, iron oxide nanoparticles were formed and thus, the method is very simple and fast. UV-VIS spectra showed the strong absorption band in the visible region. SEM images showed discrete spherical shaped particles and EDS spectra confirmed the iron and oxygen presence. The XRD results depicted the crystalline structure of iron oxide nanoparticles. FT-IR spectra portrayed the existence of functional groups of phytochemicals which are probably involved in the formation and stabilization of nanoparticles. The iron oxide nanoparticles exhibited effective inhibition against E. coli and S. epidermidis which may find its applications in the antibacterial drug development. Furthermore, the catalytic activity of the nanoparticles as Fenton-like catalyst was successfully investigated for the degradation of Rhodamine-B dye. This outcome could play a prominent role in the wastewater treatment.

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

PubMed Central

2014-01-01

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C16-iron oxide (PHEA-C16-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C16-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C16-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C16. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C16-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C16-iron oxide nanoparticles. Therefore, PHEA-C16-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes. PMID:24438671

Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

NASA Astrophysics Data System (ADS)

Jiao, Weizhou; Qin, Yuejiao; Luo, Shuai; Feng, Zhirong; Liu, Youzhi

2017-02-01

Nanoscale zero-valent iron (nZVI) was continuously prepared by high-gravity reaction precipitation through a novel impinging stream-rotating packed bed (IS-RPB). Reactant solutions of FeSO4 and NaBH4 were conducted into the IS-RPB with flow rates of 60 L/h and rotating speed of 1000 r/min for the preparation of nZVI. As-prepared nZVI obtained by IS-RPB were quasi-spherical morphology and almost uniformly distributed with a particle size of 10-20 nm. The reactivity of nZVI was estimated by the degradation of 100 ml nitrobenzene (NB) with initial concentration of 250 mg/L. The optimum dosage of nZVI obtained by IS-RPB was 4.0 g/L as the NB could be completely removed within 10 min, which reduced 20% compared with nZVI obtained by stirred tank reactor (STR). The reduction of NB and production of aniline (AN) followed pseudo-first-order kinetics, and the pseudo-first-order rate constants were 0.0147 and 0.0034 s-1, respectively. Furthermore, the as-prepared nZVI using IS-RPB reactor in this work can be used within a relatively wide range pH of 1-9.

Efficient sorption and reduction of U(VI) on zero-valent iron-polyaniline-graphene aerogel ternary composite.

PubMed

Chen, Lili; Feng, Shaojie; Zhao, Donglin; Chen, Shaohua; Li, Feifei; Chen, Changlun

2017-03-15

In this work, zero-valent iron-polyaniline-graphene aerogel composite (Fe-PANI-GA) was prepared and applied in the removal of U(VI) from aqueous solutions by batch sorption experiments. The experimental results showed that the Fe-PANI-GA composite had an excellent removal capacity for the removal of U(VI) in acidic solutions. The results also showed that the maximum removal capacity of the Fe-PANI-GA toward U(VI) was 350.47mg/g at pH 5.5. The sorption kinetics data were well-described by pseudo-second-order. The sorption isotherms of U(VI) fitted well with Langmuir isotherm and exhibited better removal efficiency with the increase of temperature. The thermodynamic parameters (ΔG, ΔS, ΔH) indicated that the sorption of U(VI) on the Fe-PANI-GA was an endothermic and spontaneous process. Moreover, removal mechanisms were studied based on the results of XRD, FTIR and XPS. Both U(VI) sorption and partially reductive precipitation of U(VI) to U(IV) contributed to the removal of U(VI) on Fe-PANI-GA. Therefore, Fe-PANI-GA was an economic and effective material for the removal of uranium from nuclear waste in practical application. Copyright © 2016 Elsevier Inc. All rights reserved.

Ecotoxicological effects on earthworms of fresh and aged nano-sized zero-valent iron (nZVI) in soil.

PubMed

El-Temsah, Yehia S; Joner, Erik J

2012-09-01

Although nano-sized zero-valent iron (nZVI) has been used for several years for remediation of contaminated soils and aquifers, only a limited number of studies have investigated secondary environmental effects and ecotoxicity of nZVI to soil organisms. In this study we therefore measured the ecotoxicological effects of nZVI coated with carboxymethyl cellulose on two species of earthworms, Eisenia fetida and Lumbricus rubellus, using standard OECD methods with sandy loam and artificial OECD soil. Earthworms were exposed to nZVI concentrations ranging from 0 to 2000 mg nZVI kg soil(-1) added freshly to soil or aged in non-saturated soil for 30 d prior to exposure. Regarding avoidance, weight changes and mortality, both earthworm species were significantly affected by nZVI concentrations ≥500 mg kg(-1)soil. Reproduction was affected also at 100 mg nZVI kg(-1). Toxicity effects of nZVI were reduced after aging with larger differences between soils compared to non-aged soils. We conclude that doses ≥500 mg nZVI kg(-1) are likely to give acute adverse effects on soil organisms, and that effects on reproduction may occur at significantly lower concentrations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Novel synthesis of carbon spheres supported nanoscale zero-valent iron for removal of metronidazole

NASA Astrophysics Data System (ADS)

Wang, Xiangyu; Du, Yi; Ma, Jun

2016-12-01

For the first time, carbon spheres-supported nanoscale zero-valent iron (NZVI/CSs) were successfully synthesized as functionalized composite via liquid phase reduction method and adopted for removal of a typical antibiotic, metronidazole (MNZ), from wastewater. The resultant composite (NZVI/CSs) exhibit higher reactivity, excellent stability, enhanced dispersion, and improved longevity over the reaction course due to the presence of the charged carboxyl groups and hydroxyl groups on the surfaces of CSs. The results show that 94.18% of MNZ was removed using NZVI/CSs after 6 min, while only 36.45% and 8.78% of MNZ were removed using NZVI and CSs, respectively. The galvanic cell system between NZVI and CSs was essential for enhancing MNZ reduction in aqueous solution. Furthermore, the new findings include kinetics for MNZ removal by NZVI/CSs composite could be well expressed by a revised two-parameter pseudo-first-order model. Finally, the possible degradation mechanism was proposed, which was based on the analysis of degraded products by high performance liquid chromatography-mass spectrometry (HPLC-MS). Different important factors impacting on MNZ removal (including mass ratio of NZVI to CSs, initial concentration, pH value and solution temperature) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.

Structural Evolution of Nanoscale Zero-Valent Iron (nZVI) in Anoxic Co2+ Solution: Interactional Performance and Mechanism

PubMed Central

Zhang, Yalei; Chen, Wen; Dai, Chaomeng; Zhou, Chuanlong; Zhou, Xuefei

2015-01-01

The structures of nanoscale zero-valent iron (nZVI) particles evolving during reactions, and the reactions are influenced by the evolved structures. To understand the removal process in detail, it is important to investigate the relationships between the reactions and structural evolution. Using high resolution-transmission electron microscopy (HR-TEM), typical evolved structures (sheet coprecipitation and cavity corrosion) of nZVI in anoxic Co2+ solutions were revealed. The system pH (pH measured in mixture), which controls the stability of coprecipitation and the nZVI corrosion rate, were found to be the determining factors of structural evolutions. X-ray photoelectron spectroscopy (XPS) results indicated that the formation and dissolution of sheet structure impacts on the ratio of Fe(0) on the nZVI surface and the surface Co2+ reduction. The cavity structure provides the possibility of Co migration from the surface to the bulk of nZVI, leading to continuous removal. Subacidity conditions could accelerate the evolution and improve the removal; the results of structurally controlled reactions further indicated that the removal was suspended by the sheet structure and enhanced by cavity structure. The results and discussion in this paper revealed the “structural influence” crucial for the full and dynamical understanding of nZVI reactions. PMID:26355955

Structural Evolution of Nanoscale Zero-Valent Iron (nZVI) in Anoxic Co(2+) Solution: Interactional Performance and Mechanism.

PubMed

Zhang, Yalei; Chen, Wen; Dai, Chaomeng; Zhou, Chuanlong; Zhou, Xuefei

2015-09-10

The structures of nanoscale zero-valent iron (nZVI) particles evolving during reactions, and the reactions are influenced by the evolved structures. To understand the removal process in detail, it is important to investigate the relationships between the reactions and structural evolution. Using high resolution-transmission electron microscopy (HR-TEM), typical evolved structures (sheet coprecipitation and cavity corrosion) of nZVI in anoxic Co(2+) solutions were revealed. The system pH (pH measured in mixture), which controls the stability of coprecipitation and the nZVI corrosion rate, were found to be the determining factors of structural evolutions. X-ray photoelectron spectroscopy (XPS) results indicated that the formation and dissolution of sheet structure impacts on the ratio of Fe(0) on the nZVI surface and the surface Co(2+) reduction. The cavity structure provides the possibility of Co migration from the surface to the bulk of nZVI, leading to continuous removal. Subacidity conditions could accelerate the evolution and improve the removal; the results of structurally controlled reactions further indicated that the removal was suspended by the sheet structure and enhanced by cavity structure. The results and discussion in this paper revealed the "structural influence" crucial for the full and dynamical understanding of nZVI reactions.

Structural Evolution of Nanoscale Zero-Valent Iron (nZVI) in Anoxic Co2+ Solution: Interactional Performance and Mechanism

NASA Astrophysics Data System (ADS)

Zhang, Yalei; Chen, Wen; Dai, Chaomeng; Zhou, Chuanlong; Zhou, Xuefei

2015-09-01

The structures of nanoscale zero-valent iron (nZVI) particles evolving during reactions, and the reactions are influenced by the evolved structures. To understand the removal process in detail, it is important to investigate the relationships between the reactions and structural evolution. Using high resolution-transmission electron microscopy (HR-TEM), typical evolved structures (sheet coprecipitation and cavity corrosion) of nZVI in anoxic Co2+ solutions were revealed. The system pH (pH measured in mixture), which controls the stability of coprecipitation and the nZVI corrosion rate, were found to be the determining factors of structural evolutions. X-ray photoelectron spectroscopy (XPS) results indicated that the formation and dissolution of sheet structure impacts on the ratio of Fe(0) on the nZVI surface and the surface Co2+ reduction. The cavity structure provides the possibility of Co migration from the surface to the bulk of nZVI, leading to continuous removal. Subacidity conditions could accelerate the evolution and improve the removal; the results of structurally controlled reactions further indicated that the removal was suspended by the sheet structure and enhanced by cavity structure. The results and discussion in this paper revealed the “structural influence” crucial for the full and dynamical understanding of nZVI reactions.

Degradation of bromamine acid by nanoscale zero-valent iron (nZVI) supported on sepiolite.

PubMed

Fei, Xuening; Cao, Lingyun; Zhou, Lifeng; Gu, Yingchun; Wang, Xiaoyang

2012-01-01

Sepiolite, a natural nano-material, was chosen as a carrier to prepare supported nanoscale zero-valent iron (nZVI). The effects of preparation conditions, including mass ratio of nZVI and activated sepiolite and preparation pH value, on properties of the supported nZVI were investigated. The results showed that the optimal mass ratio of nZVI and sepiolite was 1.12:1 and the optimal pH value was 7. The supported nZVI was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS), and furthermore an analogy model of the supported nZVI was set up. Compared with the nZVI itself, the supported nZVI was more stable in air and possessed better water dispersibility, which were beneficial for the degradation of bromamine acid aqueous solution. The degradation characteristics, such as effects of supported nZVI dosage, initial concentration and initial pH value of the solution on the decolorization efficiency were also investigated. The results showed that in an acidic environment the supported nZVI with a dosage of 2 g/L showed high activity in the degradation of bromamine acid with an initial concentration of 1,000 mg/L, and the degree of decolorization could reach up to 98%.

Zero-valent iron enhanced methanogenic activity in anaerobic digestion of waste activated sludge after heat and alkali pretreatment.

PubMed

Zhang, Yaobin; Feng, Yinghong; Quan, Xie

2015-04-01

Heat or alkali pretreatment is the effective method to improve hydrolysis of waste sludge and then enhance anaerobic sludge digestion. However the pretreatment may inactivate the methanogens in the sludge. In the present work, zero-valent iron (ZVI) was used to enhance the methanogenic activity in anaerobic sludge digester under two methanogens-suppressing conditions, i.e. heat-pretreatment and alkali condition respectively. With the addition of ZVI, the lag time of methane production was shortened, and the methane yield increased by 91.5% compared to the control group. The consumption of VFA was accelerated by ZVI, especially for acetate, indicating that the acetoclastic methanogenesis was enhanced. In the alkali-condition experiment, the hydrogen produced decreased from 27.6 to 18.8 mL when increasing the ZVI dosage from 0 to 10 g/L. Correspondingly, the methane yield increased from 1.9 to 32.2 mL, which meant that the H2-utilizing methanogenes was enriched. These results suggested that the addition of ZVI into anaerobic digestion of sludge after pretreated by the heat or alkali process could efficiently recover the methanogenic activity and increase the methane production and sludge reduction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation mechanisms of DDX induced by the addition of toluene and glycerol as cosubstrates in a zero-valent iron pretreated soil.

PubMed

Velasco, Antonio; Aburto-Medina, Arturo; Shahsavari, Esmaeil; Revah, Sergio; Ortiz, Irmene

2017-01-05

Abiotic and biotic processes can be used to remediate DDX (DDT, DDD, DDE, and DDNS) contaminated soils; these processes can be fostered using specific carbon-amendments to stimulate particular soil indigenous microbial communities to improve rates or extent of degradation. In this study, toluene and glycerol were evaluated as cosubstrates under aerobic and anoxic conditions to determine the degradation efficiencies of DDX and to elucidate possible degradation mechanisms. Slurry microcosms experiments were performed during 60 days using pretreated soil with zero-valent iron (ZVI). Toluene addition enhanced the percentage of degradation of DDX. DDNS was the main compound degraded (around 86%) under aerobic conditions, suggesting cometabolic degradation of DDX by toluene-degrading soil bacteria. Glycerol addition under anoxic conditions favored the abiotic degradation of DDX mediated by sulfate-reducing bacteria activity, where DDT was the main compound degraded (around 90%). The 16S rDNA metagenomic analyses revealed Rhodococcus ruber and Desulfosporosinus auripigmenti as the predominant bacterial species after 40 days of treatment with toluene and glycerol additions, respectively. This study provides evidence of biotic and abiotic DDX degradation by the addition of toluene and glycerol as cosubstrates in ZVI pretreated DDX-contaminated soil. Copyright © 2016 Elsevier B.V. All rights reserved.

Environmental Remediation and Application of Nanoscale Zero-Valent Iron and Its Composites for the Removal of Heavy Metal Ions: A Review.

PubMed

Zou, Yidong; Wang, Xiangxue; Khan, Ayub; Wang, Pengyi; Liu, Yunhai; Alsaedi, Ahmed; Hayat, Tasawar; Wang, Xiangke

2016-07-19

The presence of heavy metals in the industrial effluents has recently been a challenging issue for human health. Efficient removal of heavy metal ions from environment is one of the most important issues from biological and environmental point of view, and many studies have been devoted to investigate the environmental behavior of nanoscale zerovalent iron (NZVI) for the removal of toxic heavy metal ions, present both in the surface and underground wastewater. The aim of this review is to show the excellent removal capacity and environmental remediation of NZVI-based materials for various heavy metal ions. A new look on NZVI-based materials (e.g., modified or matrix-supported NZVI materials) and possible interaction mechanism (e.g., adsorption, reduction and oxidation) and the latest environmental application. The effects of various environmental conditions (e.g., pH, temperature, coexisting oxy-anions and cations) and potential problems for the removal of heavy metal ions on NZVI-based materials with the DFT theoretical calculations and EXAFS technology are discussed. Research shows that NZVI-based materials have satisfactory removal capacities for heavy metal ions and play an important role in the environmental pollution cleanup. Possible improvement of NZVI-based materials and potential areas for future applications in environment remediation are also proposed.

Reduction of trichloroethylene and nitrate by zero-valent iron with peat.

PubMed

Min, Jee-Eun; Kim, Meejeong; Pardue, John H; Park, Jae-Woo

2008-02-01

The feasibility of using zero-valent iron (ZVI) and peat mixture as in situ barriers for contaminated sediments and groundwater was investigated. Trichloroethylene (TCE) and nitrate (NO(3)(-)), redox sensitive contaminants were reduced by ZVI and peat soil mixture under anaerobic condition. Peat was used to support the sorption of TCE, microbial activity for biodegradation of TCE and denitrification while TCE and nitrate were reduced by ZVI. Decreases in TCE concentrations were mainly due to ZVI, while peat supported denitrifying microbes and further affected the sorption of TCE. Due to the competition of electrons, nitrate reduction was inhibited by TCE, while TCE reduction was not affected by nitrate. From the results of peat and sterilized peat, it can be concluded that peat was involved in both dechlorination and denitrification but biological reduction of TCE was negligible compared to that of nitrate. The results from hydrogen and methane gas analyses confirmed that hydrogen utilization by microbes and methanogenic process had occurred in the ZVI-peat system. Even though effect of the peat on TCE reduction were quantitatively small, ZVI and peat contributed to the removal of TCE and nitrate independently. The 16S rRNA analysis revealed that viable bacterial diversity was narrow and the most frequently observed genera were Bacillus and Staphylococcus spp.

Remediation of trichloroethylene-contaminated groundwater by three modifier-coated microscale zero-valent iron.

PubMed

Han, Jun; Xin, Jia; Zheng, Xilai; Kolditz, Olaf; Shao, Haibing

2016-07-01

Building a microscale zero-valent iron (mZVI) reaction zone is a promising in situ remediation technology for restoring groundwater contaminated by trichloroethylene (TCE). In order to determine a suitable modifier that could not only overcome gravity sedimentation of mZVI but also improve its remediation efficiency for TCE, the three biopolymers xanthan gum (XG), guargum (GG), and carboxymethyl cellulose (CMC) were employed to coat mZVI for surface modification. The suspension stability of the modified mZVI and its TCE removal efficiency were systematically investigated. The result indicated that XG as a shear-thinning fluid showed the most remarkable efficiency of preventing mZVI from gravity sedimentation and enhancing the TCE removal efficiency by mZVI. In a 480-h experiment, the presence of XG (3 g L(-1)) increased the TCE removal efficiency by 31.85 %, whereas GG (3 g L(-1)) and CMC (3 g L(-1)) merely increased by 15.61 and 9.69 % respectively. The pH value, Eh value, and concentration of ferrous ion as functions of the reaction time were recorded in all the reaction systems, which indicated that XG worked best in buffering the pH value of the solution and inhibiting surface passivation of mZVI.

Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon.

PubMed

Lewis, Ariel S; Huntington, Thomas G; Marvin-DiPasquale, Mark C; Amirbahman, Aria

2016-05-01

Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model.

PubMed

Hwang, Hyoun-Tae; Jeen, Sung-Wook; Sudicky, Edward A; Illman, Walter A

2015-01-01

The applicability of a newly-developed chain-decay multispecies model (CMM) was validated by obtaining kinetic rate constants and branching ratios along the reaction pathways of trichloroethene (TCE) reduction by zero-valent iron (ZVI) from column experiments. Changes in rate constants and branching ratios for individual reactions for degradation products over time for two columns under different geochemical conditions were examined to provide ranges of those parameters expected over the long-term. As compared to the column receiving deionized water, the column receiving dissolved CaCO3 showed higher mean degradation rates for TCE and all of its degradation products. However, the column experienced faster reactivity loss toward TCE degradation due to precipitation of secondary carbonate minerals, as indicated by a higher value for the ratio of maximum to minimum TCE degradation rate observed over time. From the calculated branching ratios, it was found that TCE and cis-dichloroethene (cis-DCE) were dominantly dechlorinated to chloroacetylene and acetylene, respectively, through reductive elimination for both columns. The CMM model, validated by the column test data in this study, provides a convenient tool to determine simultaneously the critical design parameters for permeable reactive barriers and natural attenuation such as rate constants and branching ratios. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of the effects of nanoscale zero-valent iron (nZVI) dispersants on intrinsic biodegradation of trichloroethylene (TCE).

PubMed

Chang, Y C; Huang, S C; Chen, K F

2014-01-01

In this study, the biodegradability of nanoscale zero-valent iron (nZVI) dispersants and their effects on the intrinsic biodegradation of trichloroethylene (TCE) were evaluated. Results of a microcosm study show that the biodegradability of three dispersants followed the sequence of: polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A) > polyoxyethylene (20) sorbitan monolaurate (Tween 20) > polyacrylic acid (PAA) under aerobic conditions, and PV3A > Tween 20 > PAA under anaerobic conditions. Natural biodegradation of TCE was observed under both aerobic and anaerobic conditions. No significant effects were observed on the intrinsic biodegradation of TCE under aerobic conditions with the presence of the dispersants. The addition of PAA seemed to have a slightly adverse impact on anaerobic TCE biodegradation. Higher accumulation of the byproducts of anaerobic TCE biodegradation was detected with the addition of PV3A and Tween 20. The diversity of the microbial community was enhanced under aerobic conditions with the presence of more biodegradable PV3A and Tween 20. The results of this study indicate that it is necessary to select an appropriate dispersant for nZVI to prevent a residual of the dispersant in the subsurface. Additionally, the effects of the dispersant on TCE biodegradation and the accumulation of TCE biodegrading byproducts should also be considered.

Integrating classical and molecular approaches to evaluate the impact of nanosized zero-valent iron (nZVI) on soil organisms.

PubMed

Saccà, Maria Ludovica; Fajardo, Carmen; Costa, Gonzalo; Lobo, Carmen; Nande, Mar; Martin, Margarita

2014-06-01

Nanosized zero-valent iron (nZVI) is a new option for the remediation of contaminated soil and groundwater, but the effect of nZVI on soil biota is mostly unknown. In this work, nanotoxicological studies were performed in vitro and in two different standard soils to assess the effect of nZVI on autochthonous soil organisms by integrating classical and molecular analysis. Standardised ecotoxicity testing methods using Caenorhabditis elegans were applied in vitro and in soil experiments and changes in microbial biodiversity and biomarker gene expression were used to assess the responses of the microbial community to nZVI. The classical tests conducted in soil ruled out a toxic impact of nZVI on the soil nematode C. elegans in the test soils. The molecular analysis applied to soil microorganisms, however, revealed significant changes in the expression of the proposed biomarkers of exposure. These changes were related not only to the nZVI treatment but also to the soil characteristics, highlighting the importance of considering the soil matrix on a case by case basis. Furthermore, due to the temporal shift between transcriptional responses and the development of the corresponding phenotype, the molecular approach could anticipate adverse effects on environmental biota. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

USGS Publications Warehouse

Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

2016-01-01

Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

Microbial Sulfate Reduction Enhances Arsenic Mobility Downstream of Zerovalent-Iron-Based Permeable Reactive Barrier.

PubMed

Kumar, Naresh; Couture, Raoul-Marie; Millot, Romain; Battaglia-Brunet, Fabienne; Rose, Jérôme

2016-07-19

We assessed the potential of zerovalent-iron- (Fe(0)) based permeable reactive barrier (PRB) systems for arsenic (As) remediation in the presence or absence of microbial sulfate reduction. We conducted long-term (200 day) flow-through column experiments to investigate the mechanisms of As transformation and mobility in aquifer sediment (in particular, the PRB downstream linkage). Changes in As speciation in the aqueous phase were monitored continuously. Speciation in the solid phase was determined at the end of the experiment using X-ray absorption near-edge structure (XANES) spectroscopy analysis. We identified thio-As species in solution and AsS in solid phase, which suggests that the As(V) was reduced to As(III) and precipitated as AsS under sulfate-reducing conditions and remained as As(V) under abiotic conditions, even with low redox potential and high Fe(II) content (4.5 mM). Our results suggest that the microbial sulfate reduction plays a key role in the mobilization of As from Fe-rich aquifer sediment under anoxic conditions. Furthermore, they illustrate that the upstream-downstream linkage of PRB affects the speciation and mobility of As in downstream aquifer sediment, where up to 47% of total As initially present in the sediment was leached out in the form of mobile thio-As species.

Nanoscale zero-valent metals: a review of synthesis, characterization, and applications to environmental remediation.

PubMed

Li, Lingyun; Hu, Jiwei; Shi, Xuedan; Fan, Mingyi; Luo, Jin; Wei, Xionghui

2016-09-01

Engineered nanoscale zero-valent metals (NZVMs) representing the forefront of technologies have been considered as promising materials for environmental remediation and antimicrobial effect, due to their high reducibility and strong adsorption capability. This review is focused on the methodology for synthesis of bare NZVMs, supported NZVMs, modified NZVMs, and bimetallic systems with both traditional and green methods. Recent studies have demonstrated that self-assembly methods can play an important role for obtaining ordered, controllable, and tunable NZVMs. In addition to common characterization methods, the state-of-the-art methods have been developed to obtain the properties of NZVMs (e.g., granularity, size distribution, specific surface area, shape, crystal form, and chemical bond) with the resolution down to subnanometer scale. These methods include spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), electron energy-loss spectroscopy (EELS), and near edge X-ray absorption fine structure (NEXAFS). A growing body of experimental data has proven that nanoscale zero-valent iron (NZVI) is highly effective and versatile. This article discusses the applications of NZVMs to treatment of heavy metals, halogenated organic compounds, polycyclic aromatic hydrocarbons, nutrients, radioelements, and microorganisms, using both ex situ and in situ methods. Furthermore, this paper briefly describes the ecotoxicological effects for NZVMs and the research prospects related to their synthesis, modification, characterization, and applications.

Progress toward clonable inorganic nanoparticles

NASA Astrophysics Data System (ADS)

Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi L.; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth A. H.; Ackerson, Christopher J.

2015-10-01

Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04097c

Targeted iron oxide nanoparticles for the enhancement of radiation therapy

PubMed Central

Hauser, Anastasia K.; Mitov, Mihail I.; Daley, Emily F.; McGarry, Ronald C.; Anderson, Kimberly W.; Hilt, J. Zach

2017-01-01

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. PMID:27521615

Oral exposure to polystyrene nanoparticles effects iron absorption

USDA-ARS?s Scientific Manuscript database

The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron trans...

Comparison of reductive dechlorination of p-chlorophenol using Fe0 and nanosized Fe0.

PubMed

Cheng, Rong; Wang, Jian-Long; Zhang, Wei-xian

2007-06-01

Chlorophenols, as a kind of important contaminants in groundwater, are toxic and difficult to biodegrade. Laboratory tests were conducted to examine zero-valent iron as an enhancing agent in the dechlorination of chlorinated organic compounds. Nanoscale iron particles were synthesized from common precursors KBH(4) and FeSO(4). Batch experiments were performed to investigate the reduction of p-chlorophenol (4-CP) by both common Fe(0) and nanoscale Fe(0). Comparison of 300 mesh/100 mesh/commercial reductive iron powders showed that size of iron particles played an important role in reduction process. Initial concentration and pretreatment of iron particles also influenced the chlorination rate. Nanoscale Fe(0) offered much more advantages for treatment of 4-CP compared with common iron particles, such as stability and durability. And they can be used to treat contaminants in groundwater over a long time. Among different parts of synthesized nanoscale iron particle solution, the very fine particles were the major agent for treatment of pollutants. As for preservation of nanoscale Fe(0), ethanol was recommended.

Novel combination of zero-valent Cu and Ag nanoparticles @ cellulose acetate nanocomposite for the reduction of 4-nitro phenol.

PubMed

Khan, Farman Ullah; Asimullah; Khan, Sher Bahadar; Kamal, Tahseen; Asiri, Abdullah M; Khan, Ihsan Ullah; Akhtar, Kalsoom

2017-09-01

A very simple and low-cost procedure has been adopted to synthesize efficient copper (Cu), silver (Ag) and copper-silver (Cu-Ag) mixed nanoparticles on the surface of pure cellulose acetate (CA) and cellulose acetate-copper oxide nanocomposite (CA-CuO). All nanoparticles loaded onto CA and CA-CuO presented excellent catalytic ability, but Cu-Ag nanoparticles loaded onto CA-CuO (Cu 0 -Ag 0 /CA-CuO) exhibited outstanding catalytic efficiency to convert 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH 4 . Additionally, the Cu 0 -Ag 0 /CA-CuO can be easily recovered by removing the sheet from the reaction media, and can be recycled several times, maintaining high catalytic ability for four cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrasmall water-soluble metal-iron oxide nanoparticles as T1-weighted contrast agents for magnetic resonance imaging.

PubMed

Zeng, Leyong; Ren, Wenzhi; Zheng, Jianjun; Cui, Ping; Wu, Aiguo

2012-02-28

Using an improved hydrolysis method of inorganic salts assisted with water-bath incubation, ultrasmall water-soluble metal-iron oxide nanoparticles (including Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles) were synthesized in aqueous solutions, which were used as T(1)-weighted contrast agents for magnetic resonance imaging (MRI). The morphology, structure, MRI relaxation properties and cytotoxicity of the as-prepared metal-iron oxide nanoparticles were characterized, respectively. The results showed that the average sizes of nanoparticles were about 4 nm, 4 nm and 5 nm for Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles, respectively. Moreover, the nanoparticles have good water dispersibility and low cytotoxicity. The MRI test showed the strong T(1)-weighted, but the weak T(2)-weighted MRI performance of metal-iron oxide nanoparticles. The high T(1)-weighted MRI performance can be attributed to the ultrasmall size of metal-iron oxide nanoparticles. Therefore, the as-prepared metal-iron oxide nanoparticles with good water dispersibility and ultrasmall size can have potential applications as T(1)-weighted contrast agent materials for MRI.

Magnetic Characterization of Iron Oxide Nanoparticles for Biomedical Applications.

PubMed

Maldonado-Camargo, Lorena; Unni, Mythreyi; Rinaldi, Carlos

2017-01-01

Iron oxide nanoparticles are of interest in a wide range of biomedical applications due to their response to applied magnetic fields and their unique magnetic properties. Magnetization measurements in constant and time-varying magnetic field are often carried out to quantify key properties of iron oxide nanoparticles. This chapter describes the importance of thorough magnetic characterization of iron oxide nanoparticles intended for use in biomedical applications. A basic introduction to relevant magnetic properties of iron oxide nanoparticles is given, followed by protocols and conditions used for measurement of magnetic properties, along with examples of data obtained from each measurement, and methods of data analysis.

Oxidation of nanoscale zero-valent iron under sufficient and limited dissolved oxygen: Influences on aggregation behaviors.

PubMed

Jiang, Danlie; Hu, Xialin; Wang, Rui; Yin, Daqiang

2015-03-01

Oxidations of nanoscale zero-valent iron (nZVI) under aerobic (dissolved oxygen≈8mgL(-1)) and anaerobic (dissolved oxygen <3mgL(-1)) conditions were simulated, and their influences on aggregation behaviors of nZVI were investigated. The two oxidation products were noted as HO-nZVI (nZVI oxidized in highly oxygenated water) and LO-nZVI (nZVI oxidized in lowly oxygenated water) respectively. The metallic iron of the oxidized nZVI was almost exhausted (Fe(0)≈8±5%), thus magnetization mainly depended on magnetite content. Since sufficient dissolved oxygen led to the much less magnetite (∼15%) in HO-nZVI than that in LO-nZVI (>90%), HO-nZVI was far less magnetic (Ms=88kAm(-1)) than LO-nZVI (Ms=365kAm(-1)). Consequently, HO-nZVI formed small agglomerates (228±10nm), while LO-nZVI tended to form chain-like aggregations (>1μm) which precipitated rapidly. Based on the EDLVO theory, we suggested that dissolved oxygen level determined aggregation morphologies by controlling the degree of oxidation and the magnitude of magnetization. Then the chain-like alignment of LO-nZVI would promote further aggregation, but the agglomerate morphology of HO-nZVI would eliminate magnetic forces and inhibit the aggregation while HO-nZVI remained magnetic. Our results indicated the fine colloidal stability of HO-nZVI, which might lead to the great mobility in the environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient degradation of trichloroethylene in water using persulfate activated by reduced graphene oxide-iron nanocomposite.

PubMed

Ahmad, Ayyaz; Gu, Xiaogang; Li, Li; Lv, Shuguang; Xu, Yisheng; Guo, Xuhong

2015-11-01

Graphene oxide (GO) and nano-sized zero-valent iron-reduced graphene oxide (nZVI-rGO) composite were prepared. The GO and nZVI-rGO composite were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The size of nZVI was about 6 nm as observed by TEM. The system of nZVI-rGO and persulfate (PS) was used for the degradation of trichloroethylene (TCE) in water, and showed 26.5% more efficiency as compared to nZVI/PS system. The different parameters were studied to determine the efficiency of nZVI-rGO to activate the PS system for the TCE degradation. By increasing the PS amount, TCE removal was also improved while no obvious effect was observed by varying the catalyst loading. Degradation was decreased as the TCE initial concentration was increased from 20 to 100 mg/L. Moreover, when initial solution pH was increased, efficiency deteriorated to 80%. Bicarbonate showed more negative effect on TCE removal among the solution matrix. To better understand the effects of radical species in the system, the scavenger tests were performed. The •SO4(-) and •O2(-) were predominant species responsible for TCE removal. The nZVI-rGO-activated PS process shows potential applications in remediation of highly toxic organic contaminants such as TCE present in the groundwater. Graphical abstract Persulfate activated by reduced graphene oxide and nano-sized zero-valent iron composite can be used for efficient degradation of trichloroethylene (TCE) in water.

Novel sequential process for enhanced dye synergistic degradation based on nano zero-valent iron and potassium permanganate.

PubMed

Wang, Xiangyu; Liu, Peng; Fu, Minglai; Ma, Jun; Ning, Ping

2016-07-01

A novel synergistic technology based on nano zero-valent iron (NZVI) and potassium permanganate (KMnO4) was developed for treatment of dye wastewater. The synergistic technology was significantly superior, where above 99% of methylene blue (MB) was removed, comparatively, removal efficiencies of MB with the sole technology of NZVI and KMnO4 at pH 6.39 being 52.9% and 63.1%, respectively. The advantages of this technology include (1) the in situ formed materials (manganese (hydr)oxides, iron hydroxides and MnFe oxide), resulting in the stable and high removal efficiency of MB and (2) high removal capacity in a wide range of pH value. Compared with simultaneous addition system of NZVI and KMnO4, MB removal was remarkably improved by sequential addition system, especially when KMnO4 addition time was optimized at 20 min. Analyses of crystal structure (XRD), morphological difference (FE-SEM), element valence and chemical groups (XPS) of NZVI before and after reaction had confirmed the formation of in situ materials, which obviously enhanced removal of MB by oxidation and adsorption. More importantly, the roles of in situ formed materials and degradation mechanism were innovatively investigated, and the results suggested that NCH3 bond of MB molecule was attacked by oxidants (KMnO4 and in situ manganese (hydr)oxides) at position C1 and C9, resulting in cleavage of chromophore. This study provides new insights about an applicable technology for treatment of dye wastewater. Copyright © 2016. Published by Elsevier Ltd.

Synthesis of highly reactive subnano-sized zero-valent iron using smectite clay templates.

PubMed

Gu, Cheng; Jia, Hanzhong; Li, Hui; Teppen, Brian J; Boyd, Stephen A

2010-06-01

A novel method was developed for synthesizing subnano-sized zero-valent iron (ZVI) using smectite clay layers as templates. Exchangeable Fe(III) cations compensating the structural negative charges of smectites were reduced with NaBH(4), resulting in the formation of ZVI. The unique structure of smectite clay, in which isolated exchangeable Fe(III) cations reside near the sites of structural negative charges, inhibited the agglomeration of ZVI resulting in the formation of subnanoscale ZVI particles in the smectite interlayer regions. X-ray diffraction revealed an interlayer spacing of approximately 5 A. The non-structural iron content of this clay yields a calculated ratio of two atoms of ZVI per three cation exchange sites, in full agreement with the X-ray diffraction (XRD) results since the diameter of elemental Fe is 2.5 A. The clay-templated ZVI showed superior reactivity and efficiency compared to other previously reported forms of ZVI as indicated by the reduction of nitrobenzene; structural Fe within the aluminosilicate layers was nonreactive. At a 1:3 molar ratio of nitrobenzene/non-structural Fe, a reaction efficiency of 83% was achieved, and over 80% of the nitrobenzene was reduced within one minute. These results confirm that non-structural Fe from Fe(III)-smectite was reduced predominantly to ZVI which was responsible for the reduction of nitrobenzene to aniline. This new form of subnanoscale ZVI may find utility in the development of remediation technologies for persistent environmental contaminants, for example, as components of constructed reactive domains such as reactive caps for contaminated sediments.

Synthesis of Highly Reactive Subnano-sized Zero-valent Iron using Smectite Clay Templates

PubMed Central

Gu, Cheng; Jia, Hanzhang; Li, Hui; Teppen, Brian J.; Boyd, Stephen A.

2010-01-01

A novel method was developed for synthesizing subnano-sized zero-valent iron (ZVI) using smectite clay layers as templates. Exchangeable Fe(III) cations compensating the structural negative charges of smectites were reduced with NaBH4, resulting in the formation of ZVI. The unique structure of smectite clay, in which isolated exchangeable Fe(III) cations reside near the sites of structural negative charges, inhibited the agglomeration of ZVI resulting in the formation of discrete regions of subnanoscale ZVI particles in the smectite interlayer regions. X-ray diffraction revealed an interlayer spacing of ~ 5 Å. The non-structural iron content of this clay yields a calculated ratio of two atoms of ZVI per three cation exchange sites, in full agreement with the XRD results since the diameter of elemental Fe is 2.5 Å. The clay-templated ZVI showed superior reactivity and efficiency compared to other previously reported forms of ZVI as indicated by the reduction of nitrobenzene; structural Fe within the aluminosilicate layers was nonreactive. At a 1:3 molar ratio of nitrobenzene:non-structural Fe, a reaction efficiency of 83% was achieved, and over 80% of the nitrobenzene was reduced within one minute. These results confirm that non-structural Fe from Fe(III)-smectite was reduced predominantly to ZVI which was responsible for the reduction of nitrobenzene to aniline. This new form of subnano-scale ZVI may find utility in the development of remediation technologies for persistent environmental contaminants, e.g. as components of constructed reactive domains such as reactive caps for contaminated sediments. PMID:20446730

Thermodynamics and Charging of Interstellar Iron Nanoparticles

NASA Astrophysics Data System (ADS)

Hensley, Brandon S.; Draine, B. T.

2017-01-01

Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of ≃4.5 Å, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges, particularly in regions with high gas temperatures and ionization fractions. If ≳10% of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.

Magnetic Nanoparticles for Cancer Diagnosis and Therapy

PubMed Central

Yigit, Mehmet V.; Moore, Anna

2013-01-01

Nanotechnology is evolving as a new field that has a potentially high research and clinical impact. Medicine, in particular, could benefit from nanotechnology, due to emerging applications for noninvasive imaging and therapy. One important nanotechnological platform that has shown promise includes the so-called iron oxide nanoparticles. With specific relevance to cancer therapy, iron oxide nanoparticle-based therapy represents an important alternative to conventional chemotherapy, radiation, or surgery. Iron oxide nanoparticles are usually composed of three main components: an iron core, a polymer coating, and functional moieties. The biodegradable iron core can be designed to be superparamagnetic. This is particularly important, if the nanoparticles are to be used as a contrast agent for noninvasive magnetic resonance imaging (MRI). Surrounding the iron core is generally a polymer coating, which not only serves as a protective layer but also is a very important component for transforming nanoparticles into biomedical nanotools for in vivo applications. Finally, different moieties attached to the coating serve as targeting macromolecules, therapeutics payloads, or additional imaging tags. Despite the development of several nanoparticles for biomedical applications, we believe that iron oxide nanoparticles are still the most promising platform that can transform nanotechnology into a conventional medical discipline. PMID:22274558

Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism

PubMed Central

Horniblow, Richard D.; Dowle, Miriam; Iqbal, Tariq H.; Latunde-Dada, Gladys O.; Palmer, Richard E.

2015-01-01

Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease. PMID:26378798

Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani

2015-09-25

We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between sphericalmore » and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.« less

Uniformly sized gold nanoparticles derived from PS-b-P2VP block copolymer templates for the controllable synthesis of Si nanowires.

PubMed

Lu, Jennifer Q; Yi, Sung Soo

2006-04-25

A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires have been generated. The process described herein is fully compatible with existing semiconductor processing techniques and can be readily integrated into device fabrication.

Targeted iron oxide nanoparticles for the enhancement of radiation therapy.

PubMed

Hauser, Anastasia K; Mitov, Mihail I; Daley, Emily F; McGarry, Ronald C; Anderson, Kimberly W; Hilt, J Zach

2016-10-01

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Single step, phase controlled, large scale synthesis of ferrimagnetic iron oxide polymorph nanoparticles by thermal plasma route and their rheological properties

NASA Astrophysics Data System (ADS)

Raut, Suyog A.; Mutadak, Pallavi R.; Kumar, Shiv; Kanhe, Nilesh S.; Huprikar, Sameer; Pol, Harshawardhan V.; Phase, Deodatta M.; Bhoraskar, Sudha V.; Mathe, Vikas L.

2018-03-01

In this paper we report single step large scale synthesis of highly crystalline iron oxide nanoparticles viz. magnetite (Fe3O4) and maghemite (γ-Fe2O3) via gas phase condensation process, where micron sized iron metal powder was used as a precursor. Selective phases of iron oxide were obtained by variation of gas flow rate of oxygen and hence partial pressure of oxygen inside the plasma reactor. Most of the particles were found to possesses average crystallite size of about 20-30 nm. The DC magnetization curves recorded indicate almost super-paramagnetic nature of the iron oxide magnetic nanoparticles. Further, iron oxide nanoparticles were analyzed using Raman spectroscopy, X-ray photoelectron spectroscopy and Mossbauer spectroscopy. In order to explore the feasibility of these nanoparticles for magnetic damper application, rheological studies have been carried out and compared with commercially available Carbonyl Iron (CI) particles. The nanoparticles obtained by thermal plasma route show improved dispersion which is useful for rheological applications.

Oral exposure to polystyrene nanoparticles affects iron absorption

NASA Astrophysics Data System (ADS)

Mahler, Gretchen J.; Esch, Mandy B.; Tako, Elad; Southard, Teresa L.; Archer, Shivaun D.; Glahn, Raymond P.; Shuler, Michael L.

2012-04-01

The use of engineered nanoparticles in food and pharmaceuticals is expected to increase, but the impact of chronic oral exposure to nanoparticles on human health remains unknown. Here, we show that chronic and acute oral exposure to polystyrene nanoparticles can influence iron uptake and iron transport in an in vitro model of the intestinal epithelium and an in vivo chicken intestinal loop model. Intestinal cells that are exposed to high doses of nanoparticles showed increased iron transport due to nanoparticle disruption of the cell membrane. Chickens acutely exposed to carboxylated particles (50 nm in diameter) had a lower iron absorption than unexposed or chronically exposed birds. Chronic exposure caused remodelling of the intestinal villi, which increased the surface area available for iron absorption. The agreement between the in vitro and in vivo results suggests that our in vitro intestinal epithelium model is potentially useful for toxicology studies.

Preparation and characterization of iron oxide magnetic nanoparticles functionalized by nisin.

PubMed

Gruskiene, Ruta; Krivorotova, Tatjana; Staneviciene, Ramune; Ratautas, Dalius; Serviene, Elena; Sereikaite, Jolanta

2018-05-08

Nisin is a known bacteriocin approved as a food additive for food preservation. It exhibits a wide spectrum antimicrobial activity against Gram-positive bacteria. Iron oxide magnetic nanoparticles were synthesized and characterized by X-ray diffraction method. A main part of iron oxide nanoparticles was found to be maghemite though a small quantity of magnetite could also be present. Magnetic nanoparticles were stabilized by citric, ascorbic, gallic or glucuronic acid coating. Stable iron oxide magnetic nanoparticles were functionalized by nisin using a simple and low cost adsorption method. Nisin loading was confirmed by FT-IR spectra, thermogravimetric analysis, dynamic light scattering and atomic force microscopy methods. Nisin-loaded iron oxide magnetic nanoparticles were stable at least six weeks as judged by the measurements of zeta-potential and hydrodynamic diameter. The antimicrobial activity of nisin-loaded iron oxide magnetic nanoparticles was demonstrated toward Gram-positive bacteria. Functionalized nanoparticles could therefore find the application as antimicrobials in innovative and emerging technologies based on the magnetic field. Copyright © 2018 Elsevier B.V. All rights reserved.

An image processing approach for investigation on transport of iron oxide nanoparticles (FE3O4) stabilized with poly acrylic acid in two-dimensional porous media

NASA Astrophysics Data System (ADS)

Golzar, M.; Azhdary Moghaddam, M.; Saghravani, S. F.; Dahrazma, B.

2018-04-01

Iron oxide nanoparticles were stabilized using poly acrylic acid (PAA) to yield stabilized slurry of Iron oxide nanoparticles. A two-dimensional physical model filled by glass beads was used to study the fate and transport of the iron oxide nanoparticles stabilized with PAA in porous media under saturated, steady-state flow conditions. Transport data for a nonreactive tracer, slurry of iron oxide nanoparticles stabilized with PAA were collected under similar flow conditions. The results show that low concentration slurry of iron oxide nanoparticles stabilized with PAA can be transported like a tracer without significant retardation. The image processing technique was employed to measure the tracer/nanoparticle concentration inside the 2-D model filled with glass beads. The groundwater flow model, Visual MODFLOW, was used to model the observed transport patterns through MT3DMS module. Finally, it was demonstrated that the numerical model MODFLOW can be used to predict the fate and transport characteristics of nanoparticles stabilized with PAA in groundwater aquifers.

Degradation of Toxic Chemicals by Zero-Valent Metal Nanoparticles - A Literature Review

DTIC Science & Technology

2005-11-01

oxidative reactions. Oxidative reactions are of primary interest to us as they have the potential to degrade organophosphorous nerve agents as well...a) mustard and b) nerve agent (general structure). To decontaminate mustard there are two approaches, dechlorination or oxidation of the sulfur, the...later of which is preferable due to the reversibility of the former. To decontaminate the nerve agents oxidation is required to replace X2, X3 and

Multifunctional superparamagnetic nanoparticles for enhanced drug transport in cystic fibrosis

NASA Astrophysics Data System (ADS)

Armijo, Leisha M.; Brandt, Yekaterina I.; Rivera, Antonio C.; Cook, Nathaniel C.; Plumley, John B.; Withers, Nathan J.; Kopciuch, Michael; Smolyakov, Gennady A.; Huber, Dale L.; Smyth, Hugh D.; Osinski, Marek

2012-10-01

Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and characterization of MnSe/ZnSeS alloyed quantum dots.

Multifunctional gold coated iron oxide core-shell nanoparticles stabilized using thiolated sodium alginate for biomedical applications.

PubMed

Sood, Ankur; Arora, Varun; Shah, Jyoti; Kotnala, R K; Jain, Tapan K

2017-11-01

In this paper we report synthesis of aqueous based gold coated iron oxide nanoparticles to integrate the localized surface plasma resonance (SPR) properties of gold and magnetic properties of iron oxide in a single system. Iron oxide-gold core shell nanoparticles were stabilized by attachment of thiolated sodium alginate to the surface of nanoparticles. Transmission electron microscope (TEM) micrograph presents an average elementary particle size of 8.1±2.1nm. High resolution TEM (HR-TEM) and X-ray photon spectroscopy further confirms the presence of gold shell around iron oxide core. Gold coating is responsible for reducing saturation magnetization (M s ) value from ~41emu/g to ~24emu/g - in thiolated sodium alginate stabilized gold coated iron oxide core-shell nanoparticles. The drug (curcumin) loading efficiency for the prepared nanocomposites was estimated to be around 7.2wt% (72μgdrug/mg nanoparticles) with encapsulation efficiency of 72.8%. Gold-coated iron oxide core-shell nanoparticles could be of immense importance in the field of targeted drug delivery along with capability to be used as contrast agent for MRI & CT. Copyright © 2017 Elsevier B.V. All rights reserved.

Environment friendly route of iron oxide nanoparticles from Zingiber officinale (ginger) root extract

NASA Astrophysics Data System (ADS)

Xin Hui, Yau; Yi Peng, Teoh; Wei Wen, Liu; Zhong Xian, Ooi; Peck Loo, Kiew

2016-11-01

Iron oxide nanoparticles were prepared from the reaction between the Zingiber officinale (ginger) root extracts and ferric chloride solution at 50°C for 2 h in mild stirring condition. The synthesized powder forms of nanoparticles were further characterized by using UV-Vis spectroscopy and X-ray Diffraction spectrometry. UV-Vis analysis shows the absorption peak of iron oxide nanoparticles is appeared at 370 nm. The calculation of crystallite size from the XRD showed that the average particle size of iron oxide nanoparticles was 68.43 nm. Therefore, this eco-friendly technique is low cost and large scale nanoparticles synthesis to fulfill the demand of various applications.

THERMODYNAMICS AND CHARGING OF INTERSTELLAR IRON NANOPARTICLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hensley, Brandon S.; Draine, B. T., E-mail: brandon.s.hensley@jpl.nasa.gov

Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of ≃4.5 Å, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges, particularly in regions with high gas temperatures and ionization fractions. If ≳10% of the interstellar ironmore » is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.« less

In vitro cytotoxicity of iron oxide nanoparticles: effects of chitosan and polyvinyl alcohol as stabilizing agents

NASA Astrophysics Data System (ADS)

Tran, Phong A.; Nguyen, Hiep T.; Fox, Kate; Tran, Nhiem

2018-03-01

Iron oxide magnetic nanoparticles have significant potential in biomedical applications such as in diagnosis, imaging and therapeutic agent delivery. The choice of stabilizers and surface functionalization is important as it is known to strongly influence the cytotoxicity of the nanoparticles. The present study aimed at investigating the effects of surface charges on the cytotoxicity of iron oxide nanoparticles. We used a co-precipitation method to synthesize iron oxide nanoparticles which were then stabilized with either chitosan (CS) or polyvinyl alcohol (PVA) which have net positive charge and zero charge at physiological pH, respectively. The nanoparticles were characterized in terms of size, charges and chemical oxidation state. Cytotoxicity of the nanoparticles was assessed using mouse fibroblast cells and was correlated with surface charges of the nanoparticles and their aggregation.

Do natural biofilm impact nZVI mobility and interactions with porous media? A column study.

PubMed

Crampon, Marc; Hellal, Jennifer; Mouvet, Christophe; Wille, Guillaume; Michel, Caroline; Wiener, Anke; Braun, Juergen; Ollivier, Patrick

2018-01-01

Nanoparticles (NP) used as remediation agents for groundwater treatment may interact with biofilms naturally present, altering NP mobility and/or reactivity and thereby NP effectiveness. The influence of the presence of a multi species biofilm on the mobility of two types of zero-valent iron NP (nZVI; NANOFER 25S and optimized NANOFER STAR, NanoIron s.r.o. (Czech Republic)) was tested in laboratory experiments with columns mimicking aquifer conditions. Biofilms were grown in columns filled with sand in nitrate reducing conditions using groundwater from an industrial site as inoculum. After two months growth, they were composed of several bacterial species, dominated by Pseudomonas stutzeri. Biofilm strongly affected the physical characteristics of the sand, decreasing total porosity from ~30% to ~15%, and creating preferential pathways with high flow velocities. nZVI suspensions were injected into the columns at a seepage velocity of 10mday - 1 . Presence of biofilm did not impact the concentrations of Fe at the column outlet nor the amount of total Fe retained in the sand, as attested by the measurement of magnetic susceptibility. However, it had a significant impact on NP size sorting as well as on total Fe distribution along the column. This suggests nZVI-biofilm interactions that were confirmed by microscopic observations using SEM/STEM coupled with energy-dispersive X-ray spectroscopy. Our study shows that biofilm modifies the water flow velocity in the porous media, favoring the transport of large aggregates and decreased NP mobility due to physical and chemical interactions. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and characterization of Acacia gum-Fe0Np-silica nanocomposite: an efficient Fenton-like catalyst for the degradation of Remazol Brilliant Violet dye

NASA Astrophysics Data System (ADS)

Singh, Vandana; Singh, Jadveer; Srivastava, Preeti

2018-04-01

Acacia gum-Fe0Np-silica nanocomposite (GFS1) has been crafted through sol-gel technique using a two-step process that involved the reduction of iron salt to zerovalent iron nanoparticles (Fe0Nps) followed by their impregnation within Acacia gum-silica matrix. GFS1 was characterized using Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS) techniques. GFS1 is decorated with Fe0Nps of 5 nm average size. The VSM study revealed that GFS1 has ferromagnetic nature. GFS1 was used as a heterogeneous Fenton-like catalyst for the degradation of azo dyes using Remazol Brilliant Violet (RBV) dye as a model dye. In first 5 min of operation, > 86% dye degradation was achieved and 94% dye (from 100 mg L-1 dye solution) was successfully degraded in 50 min. The dye degradation followed pseudo-first-order kinetics. The GFS1 performed efficiently well over the wide range of dye concentrations (25-200 mg L-1). The catalyst was reused for eight repeated cycles where 12.5% dye degradation was possible even in the eighth cycle. The catalyst behaved fairly well for the degradation of Metanil Yellow (MY) and Orange G (OG) dyes also. Under the optimum conditions of RBV dye degradation, Metanil Yellow (MY) and Orange G (OG) dyes were degraded to the extent of 97 and 26.3%, respectively.

Exogenous iron redistribution between brain and spleen after the administration of the 57Fe3O4 ferrofluid into the ventricle of the brain

NASA Astrophysics Data System (ADS)

Gabbasov, Raul; Polikarpov, Dmitry; Cherepanov, Valery; Chuev, Michael; Mischenko, Ilya; Loginiva, Nadezhda; Loseva, Elena; Nikitin, Maxim; Panchenko, Vladislav

2017-04-01

Iron clearance pathways after the injection of 57Fe3O4-based dextran-stabilized ferrofluid into the brain ventricles were studied by Mössbauer spectroscopy and histologically. The nanoparticles appeared in spleen tissues within 3 h after transcranial injection. We separated and independently estimated concentrations of iron encapsulated in nanoparticles and iron encapsulated in proteins in the all rat organs. It was found that the dextran coated initial nanoparticles of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection.The nanoparticles completely exited from the brain in a few weeks. The exogenous iron appeared in the spleen in 3 h after the injection and remained in the spleen for more than month. The appearance of additional component in Mössbauer spectra of spleen samples revealed a fundamental difference in the mechanisms of processing of iron nanoparticles in this organ, which was also confirmed by histological examination.

Monitoring engineered remediation with borehole radar

USGS Publications Warehouse

Lane, J.W.; Day-Lewis, F. D.; Joesten, P.K.

2007-01-01

The success of engineered remediation is predicated on correct emplacement of either amendments (e.g., vegetable-oil emulsion, lactate, molasses, etc.) or permeable reactive barriers (e.g., vegetable oil, zero-valent iron, etc.) to enhance microbial or geochemical breakdown of contaminants and treat contaminants. Currently, site managers have limited tools to provide information about the distribution of injected materials; the existence of gaps or holes in barriers; and breakdown or transformation of injected materials over time. ?? 2007 Society of Exploration Geophysicists.

The effect of granular ferric hydroxide amendment on the reduction of nitrate in groundwater by zero-valent iron.

PubMed

Song, Hocheol; Jeon, Byong-Hun; Chon, Chul-Min; Kim, Yongje; Nam, In-Hyun; Schwartz, Franklin W; Cho, Dong-Wan

2013-11-01

The feasibility of using granular ferric hydroxide (GFH) with zero-valent iron (Fe(0)) for its potential utility in enhancing nitrate reduction was investigated. The addition of 10gL(-1) GFH to 25gL(-1) Fe(0) significantly enhanced nitrate removal, resulting in 93% removal of 52.2mg-NL(-1) in 36-h as compared to 23% removal with Fe(0) alone. Surface analyses of the reacted Fe(0)/GFH revealed the presence of magnetite on the Fe(0) surface, which probably served as an electron mediator for nitrate reduction. Addition of GFH to Fe(0) also resulted in lower solution pH compared to Fe(0). The rate enhancing effect of GFH on nitrate reduction was attributed to the combined effects of magnetite formation and pH buffering by GFH. GFH amendment (100gL(-1)) significantly increased reduction capacity and longevity of Fe(0) to complete several nitrate reduction cycles before inactivation, giving a total nitrate removal of 205mg-NL(-1), while unamended Fe(0) gave only 20mg-NL(-1) before inactivation during the first reduction cycle. The overall result demonstrated the potential utility of Fe(0)/GFH system that may be developed into a viable technology for removal of nitrate from groundwater. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reactivity of Nanoscale Zero-Valent Iron in Unbuffered Systems: Effect of pH and Fe(II) Dissolution.

PubMed

Bae, Sungjun; Hanna, Khalil

2015-09-01

While most published studies used buffers to maintain the pH, there is limited knowledge regarding the reactivity of nanoscale zerovalent iron (NZVI) in poorly buffered pH systems to date. In this work, the effect of pH and Fe(II) dissolution on the reactivity of NZVI was investigated during the reduction of 4-nitrophenol (4-NP) in unbuffered pH systems. The reduction rate increased exponentially with respect to the NZVI concentration, and the ratio of dissolved Fe(II)/initial NZVI was related proportionally to the initial pH values, suggesting that lower pH (6-7) with low NZVI loading may slow the 4-NP reduction through acceleration of the dissolution of NZVI particles. Additional experiments using buffered pH systems confirmed that high pH values (8-9) can preserve the NZVI particles against dissolution, thereby enhancing the reduction kinetics of 4-NP. Furthermore, reduction tests using ferrous ion in suspensions of magnetite and maghemite showed that surface-bound Fe(II) on oxide coatings can play an important role in enhancing 4-NP reduction by NZVI at pH 8. These unexpected results highlight the importance of pH and Fe(II) dissolution when NZVI technology is applied to poorly buffered systems, particularly at a low amount of NZVI (i.e., <0.075 g/L).

Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study.

PubMed

Sheng, Guodong; Hu, Jun; Li, Hui; Li, Jiaxing; Huang, Yuying

2016-04-01

Herein, the reduction of nanoscale zero-valent iron (NZVI) and adsorption of layered double hydroxides (LDH) to sequester Cr(VI) were well combined by the immobilization of NZVI onto LDH surface (NZVI/LDH). The characterization results revealed that LDH decreased NZVI aggregation and thus increased Cr(VI) sequestration. The batch results indicated that Cr(VI) sequestration by NZVI/LDH was higher than that of NZVI, and superior to the sum of reduction and adsorption. The LDH with good anion exchange property allowed the adsorption of Cr(VI), facilitating interfacial reaction by increasing the local concentration of Cr(VI) in the NZVI vicinity. X-ray absorption near edge structure (XANES) results indicated that Cr(VI) was almost completely reduced to Cr(III) by NZVI/LDH, but Cr(VI) was partly reduced to Cr(III) by NZVI with a trace of Cr(VI) adsorbed on corrosion products. The coordination environment of Cr from extended X-ray absorption fine structure (EXAFS) analysis revealed that LDH could be a good scavenger for the insoluble products produced during reaction. So, the insoluble products on NZVI could be reduced, and its reactivity could be maintained. These results demonstrated that NZVI/LDH exhibits multiple functionalities relevant to the remediation of Cr(VI)-contaminated sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Heavy metal removal using nanoscale zero-valent iron (nZVI): Theory and application.

PubMed

Li, Shaolin; Wang, Wei; Liang, Feipeng; Zhang, Wei-Xian

2017-01-15

Treatment of wastewater containing heavy metals requires considerations on simultaneous removal of different ions, system reliability and quick separation of reaction products. In this work, we demonstrate that nanoscale zero-valent iron (nZVI) is an ideal reagent for removing heavy metals from wastewater. Batch experiments show that nZVI is able to perform simultaneous removal of different heavy metals and arsenic; reactive nZVI in uniform dispersion brings rapid changes in solution E h , enabling a facile way for reaction regulation. Microscope characterizations and settling experiments suggest that nZVI serves as solid seeds that facilitate products separation. A treatment process consisting of E h -controlled nZVI reaction, gravitational separation and nZVI recirculation is then demonstrated. Long-term (>12 months) operation shows that the process achieves >99.5% removal of As, Cu and a number of other toxic elements. The E h -controlled reaction system sustains a highly-reducing condition in reactor and reduces nZVI dosage. The process produces effluent of stable quality that meets local discharge guidelines. The gravitational separator shows high efficacy of nZVI recovery and the recirculation improves nZVI material efficiency, resulting in extraordinarily high removal capacities ((245mg As+226 mg-Cu)/g-nZVI). The work provides proof that nanomaterials can offer truly green and cost-effective solutions for wastewater treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Sulfidation of Nano Zerovalent Iron (nZVI) for Improved Selectivity During In-Situ Chemical Reduction (ISCR).

PubMed

Fan, Dimin; O'Brien Johnson, Graham; Tratnyek, Paul G; Johnson, Richard L

2016-09-06

The high reactivity of nano zerovalent iron (nZVI) leads to inefficient treatment due to competition with various natural reductant demand (NRD) processes, especially the reduction of water to hydrogen. Here we show that this limitation can be alleviated by sulfidation (i.e., modification by reducing sulfur compounds). nZVI synthesized on carboxylmethylcelluose (CMC-nZVI) was sulfidated with either sulfide or dithionite. The reactivity of the resulting materials was examined with three complementary assays: (i) direct measurement of hydrogen production, (ii) reduction of a colorimetric redox probe (indigo disulfonate, I2S), and (iii) dechlorination of trichloroethylene (TCE). The results indicate that sulfidation at S/Fe molar ratios of ≥0.3, effectively eliminates reaction with water, but retains significant reactivity with TCE. However, sulfidation with sulfide leaves most of the nZVI as Fe(0), whereas dithionite converts a majority of the nZVI to FeS (thus consuming much of the reducing capacity originally provided by the Fe(0)). Simplified numerical models show that the reduction kinetics of I2S and TCE are mainly dependent on the initial reducing equivalents and that the TCE reduction rate is affected by the aging of FeS. Overall, the results suggest that pretreatment of nZVI with reducing sulfur compounds could result in substantial improvement in nZVI selectivity.

Short-term effects of nanoscale Zero-Valent Iron (nZVI) and hydraulic shock during high-rate anammox wastewater treatment.

PubMed

Xu, Jia-Jia; Zhang, Zheng-Zhe; Ji, Zheng-Quan; Zhu, Ying-Hong; Qi, Si-Yu; Tang, Chong-Jian; Jin, Ren-Cun

2018-06-01

The stability and resilience of an anaerobic ammonium oxidation (anammox) system under transient nanoscale Zero-Valent Iron (nZVI) (50, 75 and 100 mg L -1 ), hydraulic shock (2-fold increase in flow rate) and their combination were studied in an up-flow anaerobic sludge blanket reactor. The response to the shock loads can be divided into three phases i.e. shock, inertial and recovery periods. The effects of the shock loads were directly proportional to the shock intensity. The effluent quality was gradually deteriorated after exposure to high nZVI level (100 mg L -1 ) for 2 h. The higher effluent sensitivity index and response caused by unit intensity of shock was observed under hydraulic and combined shocks. Notably, the specific anammox activity and the content of heme c were considerably reduced during the shock phase and the maximum loss rates were about 30.5% and 24.8%, respectively. Nevertheless, the extracellular polymeric substance amount in the shock phase was enhanced in varying degrees and variation tendency was disparate at all the tested shock loads. These results suggested that robustness of the anammox system was dependent on the magnitude shocks applied and the reactor resistance can be improved by reducing hydraulic retention time with the increase of nZVI concentration under these circumstances. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Comparative Study of the Adsorption of Methylene Blue onto Synthesized Nanoscale Zero-Valent Iron-Bamboo and Manganese-Bamboo Composites

PubMed Central

Shaibu, Solomon E.; Adekola, Folahan A.; Adegoke, Halimat I.; Ayanda, Olushola S.

2014-01-01

In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI) and nanoscale manganese (nMn) were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB) dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites. PMID:28788688

Nanoscale zero-valent iron/persulfate enhanced upflow anaerobic sludge blanket reactor for dye removal: Insight into microbial metabolism and microbial community

PubMed Central

Pan, Fei; Zhong, Xiaohan; Xia, Dongsheng; Yin, Xianze; Li, Fan; Zhao, Dongye; Ji, Haodong; Liu, Wen

2017-01-01

This study investigated the efficiency of nanoscale zero-valent iron combined with persulfate (NZVI/PS) for enhanced degradation of brilliant red X-3B in an upflow anaerobic sludge blanket (UASB) reactor, and examined the effects of NZVI/PS on anaerobic microbial communities during the treatment process. The addition of NZVI (0.5 g/L) greatly enhanced the decolourization rate of X-3B from 63.8% to 98.4%. The Biolog EcoPlateTM technique was utilized to examine microbial metabolism in the reactor, and the Illumina MiSeq high-throughput sequencing revealed 22 phyla and 88 genera of the bacteria. The largest genera (Lactococcus) decreased from 33.03% to 7.94%, while the Akkermansia genera increased from 1.69% to 20.23% according to the abundance in the presence of 0.2 g/L NZVI during the biological treatment process. Meanwhile, three strains were isolated from the sludge in the UASB reactors and identified by 16 S rRNA analysis. The distribution of three strains was consistent with the results from the Illumina MiSeq high throughput sequencing. The X-ray photoelectron spectroscopy results indicated that Fe(0) was transformed into Fe(II)/Fe(III) during the treatment process, which are beneficial for the microorganism growth, and thus promoting their metabolic processes and microbial community. PMID:28300176

Examination of Cr(VI) treatment by zero-valent iron using in situ, real-time X-ray absorption spectroscopy and Cr isotope measurements

NASA Astrophysics Data System (ADS)

Jamieson-Hanes, Julia H.; Lentz, Adam M.; Amos, Richard T.; Ptacek, Carol J.; Blowes, David W.

2014-10-01

A series of replicate flow-through cell experiments was conducted to characterize Cr isotope fractionation during Cr(VI) treatment by granular zero-valent iron (ZVI). Synthetic groundwater containing 50 mg L-1 Cr(VI) was pumped upward through a custom-made cell packed with ZVI under anaerobic conditions. The geochemical evolution of the system was monitored using pH and redox measurements, while aqueous effluent samples were retained for analysis of cations and Cr isotopes. Real-time, in situ X-ray absorption near edge structure (XANES) spectroscopy collected via a Kapton® window in the cell provided additional information on the speciation of the reaction products. Increases in δ53Cr values corresponding to decreases in Cr(VI) concentration suggested the occurrence of redox processes. Spectroscopic results correlated well with the isotope data, indicating reduction of Cr(VI) to Cr(III). The isotope data did not appear to follow a single trend. A two-stage system was proposed to explain the complex isotope trend, where the rapid Cr removal was associated with very little fractionation (ε = -0.2‰), whereas slower removal was associated with a greater degree of fractionation (ε = -1.2‰ to -1.5‰). Reactive transport modeling was used to quantify distinct isotope fractionation values (ε), differentiated by a significant change in the Cr removal rate.

Ecotoxicity and environmental safety related to nano-scale zerovalent iron remediation applications.

PubMed

Semerád, Jaroslav; Cajthaml, Tomáš

2016-12-01

This mini-review summarizes the current information that has been published on the various effects of nano-scale zerovalent iron (nZVI) on microbial biota, with an emphasis on reports that highlight the positive aspects of its application or its stimulatory effects on microbiota. By nature, nZVI is a highly reactive substance; thus, the possibility of nZVI being toxic is commonly suspected. Accordingly, the cytotoxicity of nZVI and the toxicity of nZVI-related products have been detected by laboratory tests and documented in the literature. However, there are numerous other published studies on its useful nature, which are usually skipped in reviews that deal only with the phenomenon of toxicity. Therefore, the objective of this article is to review both recent publications reporting the toxic effects of nZVI on microbiota and studies documenting the positive effects of nZVI on various environmental remediation processes. Although cytotoxicity is an issue of general importance and relevance, nZVI can reduce the overall toxicity of a contaminated site, which ultimately results in the creation of better living conditions for the autochthonous microflora. Moreover, nZVI changes the properties of the site in a manner such that it can also be used as a tool in a tailor-made approach to support a specific microbial community for the decontamination of a particular polluted site.

Background species effect on aqueous arsenic removal by nano zero-valent iron using fractional factorial design.

PubMed

Tanboonchuy, Visanu; Grisdanurak, Nurak; Liao, Chih-Hsiang

2012-02-29

This study describes the removal of arsenic species in groundwater by nano zero-valent iron process, including As(III) and As(V). Since the background species may inhibit or promote arsenic removal. The influence of several common ions such as phosphate (PO4(3-)), bicarbonate (HCO3-)), sulfate (SO4(2-)), calcium (Ca2+), chloride (Cl-), and humic acid (HA) were selected to evaluate their effects on arsenic removal. In particular, a 2(6-2) fractional factorial design (FFD) was employed to identify major or interacting factors, which affect arsenic removal in a significant way. As a result of FFD evaluation, PO4(3-) and HA play the role of inhibiting arsenic removal, while Ca2+ was observed to play the promoting one. As for HCO3- and Cl-, the former one inhibits As(III) removal, whereas the later one enhances its removal; on the other hand, As(V) removal was affected only slightly in the presence of HCO3- or Cl-. Hence, it was suggested that the arsenic removal by the nanoiron process can be improved through pretreatment of PO4(3-) and HA. In addition, for the groundwater with high hardness, the nanoiron process can be an advantageous option because of enhancing characteristics of Ca2+. Copyright © 2011 Elsevier B.V. All rights reserved.

Rapid and extensive debromination of decabromodiphenyl ether by smectite clay-templated subnanoscale zero-valent iron.

PubMed

Yu, Kai; Gu, Cheng; Boyd, Stephen A; Liu, Cun; Sun, Cheng; Teppen, Brian J; Li, Hui

2012-08-21

Subnanoscale zerovalent iron (ZVI) synthesized using smectite clay as a template was utilized to investigate reduction of decabromodiphenyl ether (DBDE). The results revealed that DBDE was rapidly debrominated by the prepared smectite-templated ZVI with a reaction rate 10 times greater than that by conventionally prepared nanoscale ZVI. This enhanced reduction is plausibly attributed to the smaller-sized smectite-templated ZVI clusters (∼0.5 nm) vs that of the conventional nanoscale ZVI (∼40 nm). The degradation of DBDE occurred in a stepwise debromination manner. Pentabromodiphenyl ethers were the terminal products in an alkaline suspension (pH 9.6) of smectite-templated ZVI, whereas di-, tri-, and tetrabromodiphenyl ethers formed at the neutral pH. The presence of tetrahydrofuran (THF) as a cosolvent at large volume fractions (e.g., >70%) in water reduced the debromination rates due to enhanced aggregation of clay particles and/or diminished adsorption of DBDE to smectite surfaces. Modification of clay surfaces with tetramethylammonium (TMA) attenuated the colsovent effect on the aggregation of clay particles, resulting in enhanced debromination rates. Smectite clay provides an ideal template to form subnanoscale ZVI, which demonstrated superior debromination reactivity with DBDE compared with other known forms of ZVIs. The ability to modify the nature of smectite clay surface by cation exchange reaction utilizing organic cations can be harnessed to create surface properties compatible with various contaminated sites.

Nanoscale zero-valent iron/persulfate enhanced upflow anaerobic sludge blanket reactor for dye removal: Insight into microbial metabolism and microbial community

NASA Astrophysics Data System (ADS)

Pan, Fei; Zhong, Xiaohan; Xia, Dongsheng; Yin, Xianze; Li, Fan; Zhao, Dongye; Ji, Haodong; Liu, Wen

2017-03-01

This study investigated the efficiency of nanoscale zero-valent iron combined with persulfate (NZVI/PS) for enhanced degradation of brilliant red X-3B in an upflow anaerobic sludge blanket (UASB) reactor, and examined the effects of NZVI/PS on anaerobic microbial communities during the treatment process. The addition of NZVI (0.5 g/L) greatly enhanced the decolourization rate of X-3B from 63.8% to 98.4%. The Biolog EcoPlateTM technique was utilized to examine microbial metabolism in the reactor, and the Illumina MiSeq high-throughput sequencing revealed 22 phyla and 88 genera of the bacteria. The largest genera (Lactococcus) decreased from 33.03% to 7.94%, while the Akkermansia genera increased from 1.69% to 20.23% according to the abundance in the presence of 0.2 g/L NZVI during the biological treatment process. Meanwhile, three strains were isolated from the sludge in the UASB reactors and identified by 16 S rRNA analysis. The distribution of three strains was consistent with the results from the Illumina MiSeq high throughput sequencing. The X-ray photoelectron spectroscopy results indicated that Fe(0) was transformed into Fe(II)/Fe(III) during the treatment process, which are beneficial for the microorganism growth, and thus promoting their metabolic processes and microbial community.

Kinetics and Pathways for the Debromination of Polybrominated Diphenyl Ethers by Bimetallic and Nanoscale Zerovalent Iron: Effects of Particle Properties and Catalyst

PubMed Central

Zhuang, Yuan; Jin, Luting; Luthy, Richard G.

2012-01-01

Polybrominated diphenyl ethers (PBDEs) are recognized as a new class of widely-distributed and persistent contaminants for which effective treatment and remediation technologies are needed. In this study, two kinds of commercially available nanoscale Fe° slurries (Nanofer N25 and N25S), a freeze-dried laboratory-synthesized Fe° nanoparticle (nZVI), and their palladized forms were used to investigate the effect of particle properties and catalyst on PBDE debromination kinetics and pathways. Nanofers and their palladized forms were found to debrominate PBDEs effectively. The laboratory-synthesized Fe° nanoparticles also debrominated PBDEs, but were slower due to deactivation by the freeze-drying and stabilization processes in the laboratory synthesis. An organic modifier, polyacrylic acid (PAA), bound on N25S slowed PBDE debromination by a factor of three to four compared to N25. The activity of palladized nZVI (nZVI/Pd) was optimized at 0.3 Pd/Fe wt% in our system. N25 could debrominate selected environmentally-abundant PBDEs, including BDE 209, 183, 153, 99, and 47, to end products di-BDEs, mono-BDEs and diphenyl ether (DE) in one week, while nZVI/Pd (0.3 Pd/Fe wt%) mainly resulted in DE as a final product. Step-wise major PBDE debromination pathways by unamended and palladized Fe° are described and compared. Surface precursor complex formation is an important limiting factor for palladized Fe° reduction as demonstrated by PBDE pathways where steric hindrance and rapid sequential debromination of adjacent bromines play an important role. PMID:22732301

Trichloroethene (TCE) hydrodechlorination by NiFe nanoparticles: Influence of aqueous anions on catalytic pathways.

PubMed

Han, Yanlai; Liu, Changjie; Horita, Juske; Yan, Weile

2018-08-01

Amending bulk and nanoscale zero-valent iron (ZVI) with catalytic metals significantly accelerates hydrodechlorination of groundwater contaminants such as trichloroethene (TCE). The bimetallic design benefits from a strong synergy between Ni and Fe in facilitating the production of active hydrogen for TCE reduction, and it is of research and practical interest to understand the impacts of common groundwater solutes on catalyst and ZVI functionality. In this study, TCE hydrodechlorination reaction was conducted using fresh NiFe bimetallic nanoparticles (NiFe BNPs) and those aged in chloride, sulfate, phosphate, and humic acid solutions with concurrent analysis of carbon fractionation of TCE and its daughter products. The apparent kinetics suggest that the reactivity of NiFe BNPs is relatively stable in pure water and chloride or humic acid solutions, in contrast to significant deactivation observed of PdFe bimetallic particles in similar media. Exposure to phosphate at greater than 0.1 mM led to a severe decrease in TCE reaction rate. The change in kinetic regimes from first to zeroth order with increasing phosphate concentration is consistent with consumption of reactive sites by phosphate. Despite severe kinetic effect, there is no significant shift in TCE 13 C bulk enrichment factor between the fresh and the phosphate-aged particles. Instead, pronounced retardation of TCE reaction by NiFe BNPs in deuterated water (D 2 O) points to the importance of hydrogen spillover in controlling TCE reduction rate by NiFe BNPs, and such process can be strongly affected by groundwater chemistry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Design of Fucoidan Functionalized - Iron Oxide Nanoparticles for Biomedical Applications.

PubMed

Tran, Khanh Nghia; Tran, Phuong Ha-Lien; Vo, Toi Van; Tran, Thao Truong-Dinh

2016-01-01

This research aims to develop an iron oxide nanoparticle drug delivery system utilizing a recent material discovered from ocean, fucoidan. The material has drawn much interest due to many biomedical functions that have been proven for human health. One interesting point herein is that fucoidan is not only a sulfated polysaccharide, a polymer for stabilization of iron oxide nanoparticles, but plays a role of an anticancer agent also. Various approaches were investigated to optimize the high loading efficiency and explain the mechanism of nanoparticle formations. Fucoidan was functionalized on iron oxide nanoparticles by a direct coating or via amine groups. Also, a hydrophobic part of oleic acid was conjugated to the amine groups for a more favorable loading of poorly water-soluble anticancer drugs. This study proposed a novel system and an efficient method to functionalize fucoidan on iron oxide nanoparticle systems which will lead to a facilitation of a double strength treatment of cancer.

Green Synthesis of Iron Nanoparticles and Their Environmental Applications and Implications

PubMed Central

Saif, Sadia; Tahir, Arifa; Chen, Yongsheng

2016-01-01

Recent advances in nanoscience and nanotechnology have also led to the development of novel nanomaterials, which ultimately increase potential health and environmental hazards. Interest in developing environmentally benign procedures for the synthesis of metallic nanoparticles has been increased. The purpose is to minimize the negative impacts of synthetic procedures, their accompanying chemicals and derivative compounds. The exploitation of different biomaterials for the synthesis of nanoparticles is considered a valuable approach in green nanotechnology. Biological resources such as bacteria, algae fungi and plants have been used for the production of low-cost, energy-efficient, and nontoxic environmental friendly metallic nanoparticles. This review provides an overview of various reports of green synthesised zero valent metallic iron (ZVMI) and iron oxide (Fe2O3/Fe3O4) nanoparticles (NPs) and highlights their substantial applications in environmental pollution control. This review also summarizes the ecotoxicological impacts of green synthesised iron nanoparticles opposed to non-green synthesised iron nanoparticles. PMID:28335338

The synthesis and characterization of iron nanoparticles

NASA Astrophysics Data System (ADS)

Bennett, Tyler

Nanoparticle synthesis has garnered attention for technological applications for catalysts, industrial processing, and medical applications. The size ranges for these is in the particles nanostructural domain. Pure iron nanoparticles have been of particular interest for their reactivity and relative biological inertness. Applications include cancer treatment and carrying medicine to a relevant site. Unfortunately, because of their reactivity, pure iron nanoparticles have been difficult to study. This is because of their accelerated tendency to form oxides in air, due to the increased surface area to volume ratio. Using synthesis processes with polyphenols or long chain amines, air stable iron nanoparticles have been produced with a diameter size range of ~ 2 to about ~10 nm, but apparently have transformed due to internal pressure and crystallographic defects to the FCC phase. The FCC crystals have been seen to form icosahedral and decahedral shapes. This size is within the range for use as a catalyst for the growth of both carbon nanotubes and boron nitride nanotubes as well for biomedical applications. The advantages of these kinds of catalysts are that nanotube growth can be for the first time separated from the catalyst formation. Additionally, the catalyst size can be preselected for a certain size nanotube to grow. In summary: (1) we found the size distributions of nanoparticles for various synthesis processes, (2) we discovered the right size range for growth of nanotubes from the iron nanoparticles, (3) the nanoparticles are under a very high internal pressure, (4) the nanoparticles are in the FCC phase, (5) they appear to be in icosahedral and decahedral structures, (6) they undergo room temperature twinning, (7) the FCC crystals are distorted due to carbon in octahedral sites, (8) the iron nanoparticles are stable in air, (9) adding small amounts of copper make the iron nanoparticles smaller.

Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles.

PubMed

Su, Yiming; Adeleye, Adeyemi S; Huang, Yuxiong; Sun, Xiaoya; Dai, Chaomeng; Zhou, Xuefei; Zhang, Yalei; Keller, Arturo A

2014-10-15

Nanoscale zerovalent iron (nZVI) has demonstrated high efficacy for treating nitrate or cadmium (Cd) contamination, but its efficiency for simultaneous removal of nitrate and Cd has not been investigated. This study evaluated the reactivity of nZVI to the co-contaminants and by-product formation, employed different catalysts to reduce nitrite yield from nitrate, and examined the transformation of nZVI after reaction. Nitrate reduction resulted in high solution pH, negatively charged surface of nZVI, formation of Fe3O4 (a stable transformation of nZVI), and no release of ionic iron. Increased pH and negative charge contributed to significant increase in Cd(II) removal capacity (from 40 mg/g to 188 mg/g) with nitrate present. In addition, nitrate reduction by nZVI could be catalyzed by Cd(II): while 30% of nitrate was reduced by nZVI within 2 h in the absence of Cd(II), complete nitrate reduction was observed in the presence of 40 mg-Cd/L due to the formation of Cd islands (Cd(0) and CdO) on the nZVI particles. While nitrate was reduced mostly to ammonium when Cd(II) was not present or at Cd(II) concentrations ≥ 40 mg/L, up to 20% of the initial nitrate was reduced to nitrite at Cd(II) concentrations < 40 mg/L. Among nZVI particles doped with 1 wt. % Cu, Ag, or Au, nZVI deposited with 1 wt. % Au reduced nitrite yield to less than 3% of the initial nitrate, while maintaining a high Cd(II) removal capacity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reductive Sequestration Of Pertechnetate (99TcO4–) By Nano Zerovalent Iron (nZVI) Transformed By Abiotic Sulfide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Dimin; Anitori, Roberto; Tebo, Bradley M.

2013-04-24

Under anoxic conditions, soluble 99TcO4– can be reduced to less soluble TcO2•nH2O, but the oxide is highly susceptible to reoxidation. Here we investigate an alternative strategy for remediation of Tc-contaminated groundwater whereby sequestration as Tc sulfide is favored by sulfidic conditions stimulated by nano zero-valent iron (nZVI). nZVI was pre-exposed to increasing concentrations of sulfide in simulated Hanford groundwater for 24 hrs to mimic the stages of aquifer sulfate reduction and onset of biotic sulfidogenesis. Solid-phase characterizations of the sulfidated nZVI confirmed the formation of nanocrystalline FeS phases, but higher S/Fe ratios (>0.112) did not result in the formation ofmore » significantly more FeS. The kinetics of Tc sequestration by these materials showed faster Tc removal rates with increasing S/Fe between S/Fe = 0–0.056, but decreasing Tc removal rates with S/Fe > 0.224. The more favorable Tc removal kinetics at low S/Fe could be due to a higher affinity of TcO4– for FeS (over iron oxides), and electron microscopy confirmed that the majority of the Tc was associated with FeS phases. The inhibition of Tc removal at high S/Fe appears to have been caused by excess HS–. X-ray absorption spectroscopy revealed that as S/Fe increased, Tc speciation shifted from TcO2•nH2O to TcS2. The most substantial change of Tc speciation occurred at low S/Fe, coinciding with the rapid increase of Tc removal rate. This agreement further confirms the importance of FeS in Tc sequestration.« less

Magnetic properties of iron nanoparticles prepared by exploding wire technique.

PubMed

Alqudami, Abdullah; Annapoorni, S; Lamba, Subhalakshmi; Kothari, P C; Kotnala, R K

2007-06-01

Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centrifuge. X-ray diffraction studies confirm the presence of the cubic phase of iron. These iron nanoparticles were found to exhibit fluorescence in the visible region in contrast to the normal bulk material. The room temperature hysteresis measurements upto a field of 1.0 tesla were performed on a suspension of iron particles in the solution as well as in the powders obtained by filtration. The hysteresis loops indicate that the particles are superparamagnetic in nature. The saturation magnetizations was approximately 60 emu/gm. As these iron particles are very sensitive to oxygen a coating of non-magnetic iron oxide tends to form around the particles giving it a core-shell structure. The core particle size is estimated theoretically from the magnetization measurements. Suspensions of iron nanoparticles in water have been proposed to be used as an effective decontaminant for ground water.

Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs).

PubMed

Can, Hatice Kaplan; Kavlak, Serap; ParviziKhosroshahi, Shahed; Güner, Ali

2018-03-01

Dextran-coated iron oxide nanoparticles (DIONPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. This paper reports the experimental detail for preparation, characterization and investigation of thermal and dynamical mechanical characteristics of the dextran-coated Fe 3 O 4 magnetic nanoparticles. In our work, DIONPs were prepared in a 1:2 ratio of Fe(II) and Fe(III) salt in the HCl solution with NaOH at given temperature. The obtained dextran-coated iron-oxide nanoparticles structure-property correlation was characterized by spectroscopic methods; attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and XRD. Coating dextran on the iron-oxide proof of important peaks can be seen from the ATR-FTIR. Dramatic crystallinity increment can be observed from the XRD pattern of the iron-oxide dextran nanoparticles. The thermal analysis was examined by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Dynamical mechanical properties of dextran nanoparticles were analysed by dynamic mechanical analysis (DMA). Thermal stability of the iron oxide dextran nanoparticles is higher than that of the dextran.

Cell-delivered magnetic nanoparticles caused hyperthermia-mediated increased survival in a murine pancreatic cancer model.

PubMed

Basel, Matthew T; Balivada, Sivasai; Wang, Hongwang; Shrestha, Tej B; Seo, Gwi Moon; Pyle, Marla; Abayaweera, Gayani; Dani, Raj; Koper, Olga B; Tamura, Masaaki; Chikan, Viktor; Bossmann, Stefan H; Troyer, Deryl L

2012-01-01

Using magnetic nanoparticles to absorb alternating magnetic field energy as a method of generating localized hyperthermia has been shown to be a potential cancer treatment. This report demonstrates a system that uses tumor homing cells to actively carry iron/iron oxide nanoparticles into tumor tissue for alternating magnetic field treatment. Paramagnetic iron/ iron oxide nanoparticles were synthesized and loaded into RAW264.7 cells (mouse monocyte/ macrophage-like cells), which have been shown to be tumor homing cells. A murine model of disseminated peritoneal pancreatic cancer was then generated by intraperitoneal injection of Pan02 cells. After tumor development, monocyte/macrophage-like cells loaded with iron/ iron oxide nanoparticles were injected intraperitoneally and allowed to migrate into the tumor. Three days after injection, mice were exposed to an alternating magnetic field for 20 minutes to cause the cell-delivered nanoparticles to generate heat. This treatment regimen was repeated three times. A survival study demonstrated that this system can significantly increase survival in a murine pancreatic cancer model, with an average post-tumor insertion life expectancy increase of 31%. This system has the potential to become a useful method for specifically and actively delivering nanoparticles for local hyperthermia treatment of cancer.

Arsenic in groundwaters of rural India: its geochemistry and mitigation approaches

NASA Astrophysics Data System (ADS)

Chatterjee, Debashis; Majumder, Santanu; Kundu, Amit; Barman, Sandipan; Chatterjee, Debankur; Bhattacharya, Prosun

2016-04-01

During the last few decades, arsenic (As) has been recognized as the most threatening contaminant in natural waters (especially groundwater). It has become a menace to the health of millions of people worldwide. Many large and small communities experience As contamination in groundwater and/or drinking water supplies in south-east Asia and the problem is grave in West Bengal and Bangladesh (Bengal Delta Plain, BDP) both in terms of human exposure as well as spatial coverage. It is frequently observed that As concentration in contaminated wells exceeds both WHO guideline value (10 mg/l) and stipulated National standard (50 mg/l) for both Bangladesh and India. Dissolved forms of As in the BDP water include arsenite (~50-70%), arsenate (~30-50%) and ultra-trace amount of monomethylarsonic acid and dimethylarsinic acid. Arsenite and arsenate species can interchange depending on redox potential (Eh), pH and biological processes. The prevailing local geomorphological features (surface water, sanitation, agricultural activity) can also influence the mobilization of As in addition to the dominant geological factors. Therefore, the local sedimentology and hydrogeology should also be given importance prior to implement or consider any policy to mitigate the As contamination of groundwater. Conventional treatment techniques to remove As from groundwater are costly and difficult to practice in rural areas of the BDP. There are several techniques available for groundwater As removal. Iron and Alum coagulation, softening [mediated by calcite or Mg(OH)2 formation], by reverse osmosis, using zero-valent iron and nanoparticulate zero-valent iron, several natural/synthetic metal oxides, naturally found minerals like siderite, hematite, using iron doped activated carbons, development of bio-physicochemical techniques, using granular TiO2 adsorbent are some of the many proposed removal techniques investigated by various researchers. Instead of using hazardous chemicals (e.g. chlorine, ozone in conventional method) As from groundwater can also be removed by exposure to sunlight (solar oxidation) in presence of dissolved iron (Fe) and a chelating agent (citrate, naturally available) followed by filtration with cloth or simple decantation. The technique is user friendly, low cost and easy to perform by the rural mass of the BDP.

Immobilization of Iron Nanoparticles on Multi Substrates and Its Reduction Removal of Chromium (VI) from Waste Streams

EPA Science Inventory

This article describes the in-situ synthesis and immobilization of iron nanoparticles on several substrates at room temperature using NaBH4 as a reducing agent and ascorbic acid as capping agent. The method is very effective in protecting iron nanoparticles from air oxidation for...

A MD simulation and analysis for aggregation behaviors of nanoscale zero-valent iron particles in water via MS.

PubMed

Zhao, Ying; Liu, Dongmei; Tang, Huan; Lu, Jing; Cui, Fuyi

2014-01-01

With the development of nanotechnology, more nanomaterials will enter into water environment system. Studying the existing form of nanomaterials in water environment will help people benefit from the correct use of them and to reduce the harm to human caused by them for some nanomaterials can bring polluting effect. Aggregation is a main behavior for nanoparticle in water environment. NZVI are used widely in many fields resulting in more NZVI in water environment. Molecular dynamics simulations and Materials Studio software are used to investigate the microaggregation behaviors of NZVI particles. Two scenes are involved: (1) particle size of NZVI in each simulation system is the same, but initial distance of two NZVI particles is different; (2) initial distance of two NZVI particles in each simulation system is the same, but particle size of NZVI is different. Atomistic trajectory, NP activity, total energy, and adsorption of H2O are analyzed with MS. The method provides new quantitative insight into the structure, energy, and dynamics of the aggregation behaviors of NZVI particles in water. It is necessary to understand microchange of NPs in water because it can provide theoretical research that is used to reduce polluting effect of NPs on water environment.

A MD Simulation and Analysis for Aggregation Behaviors of Nanoscale Zero-Valent Iron Particles in Water via MS

PubMed Central

Liu, Dongmei; Tang, Huan; Lu, Jing; Cui, Fuyi

2014-01-01

With the development of nanotechnology, more nanomaterials will enter into water environment system. Studying the existing form of nanomaterials in water environment will help people benefit from the correct use of them and to reduce the harm to human caused by them for some nanomaterials can bring polluting effect. Aggregation is a main behavior for nanoparticle in water environment. NZVI are used widely in many fields resulting in more NZVI in water environment. Molecular dynamics simulations and Materials Studio software are used to investigate the microaggregation behaviors of NZVI particles. Two scenes are involved: (1) particle size of NZVI in each simulation system is the same, but initial distance of two NZVI particles is different; (2) initial distance of two NZVI particles in each simulation system is the same, but particle size of NZVI is different. Atomistic trajectory, NP activity, total energy, and adsorption of H2O are analyzed with MS. The method provides new quantitative insight into the structure, energy, and dynamics of the aggregation behaviors of NZVI particles in water. It is necessary to understand microchange of NPs in water because it can provide theoretical research that is used to reduce polluting effect of NPs on water environment. PMID:25250388

The influence of carboxymethylcellulose (CMC) on the reactivity of Fe NPs toward decabrominated diphenyl ether: The Ni doping, temperature, pH, and anion effects.

PubMed

Tso, Chih-Ping; Shih, Yang-Hsin

2017-01-15

Polybrominated diphenyl ethers (PBDEs) are commonly used brominated flame retardants in many products. They have accumulated in the environment and become widely dispersed. In this study, carboxymethylcellulose (CMC) was applied to modify nanoscale zerovalent iron (NZVI) and bimetallic Ni/Fe nanoparticles (NPs) to prevent NP aggregation. In this study the removal kinetics of the decabrominated diphenyl ethers (DBDE) with CMC-stabilized Fe NPs were evaluated. CMC-stabilized Ni/Fe NPs with an average size of 86.7nm contained metallic Fe 0 and reduced Ni. The colloidal stability decreased with a decrease in pH, which was further accompanied by a change in the removal rate of DBDE. Our results showed that anions do not change the removal rates of DBDE, with the exception of 10mM NO 3 - , which induced the formation of Fe (hydro)oxides on the Fe NP surface, which could further coagulate with DBDE. This study provides important information for our understanding of the influence of CMC coatings on the reactivity of Fe NPs. Because CMC coatings prevent the passivation of Fe in the presence of anions, CMC-coated Fe NPs show potential for the in-situ remediation of PBDEs in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Ecotoxicological impact of two soil remediation treatments in Lactuca sativa seeds.

PubMed

Rede, Diana; Santos, Lúcia H M L M; Ramos, Sandra; Oliva-Teles, Filipe; Antão, Cristina; Sousa, Susana R; Delerue-Matos, Cristina

2016-09-01

Pharmaceuticals have been identified as environmental emerging pollutants and are present in different compartments, including soils. Chemical remediation showed to be a good and suitable approach for soil remediation, though the knowledge in their impact for terrestrial organisms is still limited. Therefore, in this work, two different chemical remediation treatments (Fenton oxidation and nanoremediation) were applied to a soil contaminated with an environmental representative concentration of ibuprofen (3 ng g(-1)). The phytotoxic impact of a traditional soil remediation treatment (Fenton oxidation) and of a new and more sustainable approach for soil remediation (nanoremediation using green nano-scale zero-valent iron nanoparticles (nZVIs)) was evaluated in Lactuca sativa seeds. Percentage of seed germination, root elongation, shoot length and leaf length were considered as endpoints to assess the possible acute phytotoxicity of the soil remediation treatments as well as of the ibuprofen contaminated soil. Both chemical remediation treatments showed to have a negative impact in the germination and development of lettuce seeds, exhibiting a reduction up to 45% in the percentage of seed germination and a decrease around 80% in root elongation comparatively to the contaminated soil. These results indicate that chemical soil remediation treatments could be more prejudicial for terrestrial organisms than contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Surface carbon influences on the reductive transformation of TCE in the presence of granular iron.

PubMed

Firdous, R; Devlin, J F

2018-04-05

To gain insight into the processes of transformations in zero-valent iron systems, electrolytic iron (EI) has been used as a surrogate for the commercial products actually used in barriers. This substitution facilitates mechanistic studies, but may not be fully representative of all the relevant processes at work in groundwater remediation. To address this concern, the kinetic iron model (KIM) was used to investigate sorption and reactivity differences between EI and Connelly brand GI, using TCE as a probe compound. It was observed that retardation factors (R app ) for GI varied non-linearly with influent concentrations to the columns (C o ), and declined significantly as GI aged. In contrast, R app values for EI were small and insensitive to C o , and changed minimally with iron aging. Moreover, although declines in the rate constants (k) and increases in the sorption coefficients were observed for both iron types, they were most pronounced in the case of EI. SEM scans of the EI surface before and after aging (90 days) established the appearance of carbon on the older surface. This work provides evidence that iron with a higher surface carbon content outperforms pure iron, suggesting that the carbon is actively involved in promoting TCE reduction. Copyright © 2017 Elsevier B.V. All rights reserved.

Preliminary study of injury from heating systemically delivered, nontargeted dextran–superparamagnetic iron oxide nanoparticles in mice

PubMed Central

Kut, Carmen; Zhang, Yonggang; Hedayati, Mohammad; Zhou, Haoming; Cornejo, Christine; Bordelon, David; Mihalic, Jana; Wabler, Michele; Burghardt, Elizabeth; Gruettner, Cordula; Geyh, Alison; Brayton, Cory; Deweese, Theodore L; Ivkov, Robert

2013-01-01

Aim To assess the potential for injury to normal tissues in mice due to heating systemically delivered magnetic nanoparticles in an alternating magnetic field (AMF). Materials & methods Twenty three male nude mice received intravenous injections of dextran–superparamagnetic iron oxide nanoparticles on days 1–3. On day 6, they were exposed to AMF. On day 7, blood, liver and spleen were harvested and analyzed. Results Iron deposits were detected in the liver and spleen. Mice that had received a high-particle dose and a high AMF experienced increased mortality, elevated liver enzymes and significant liver and spleen necrosis. Mice treated with low-dose superparamagnetic iron oxide nanoparticles and a low AMF survived, but had elevated enzyme levels and local necrosis in the spleen. Conclusion Magnetic nanoparticles producing only modest heat output can cause damage, and even death, when sequestered in sufficient concentrations. Dextran–superparamagnetic iron oxide nanoparticles are deposited in the liver and spleen, making these the sites of potential toxicity. PMID:22830502

Iron oxide nanoparticles stabilized with dendritic polyglycerols as selective MRI contrast agents

NASA Astrophysics Data System (ADS)

Nordmeyer, Daniel; Stumpf, Patrick; Gröger, Dominic; Hofmann, Andreas; Enders, Sven; Riese, Sebastian B.; Dernedde, Jens; Taupitz, Matthias; Rauch, Ursula; Haag, Rainer; Rühl, Eckart; Graf, Christina

2014-07-01

Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI.Monodisperse small iron oxide nanoparticles functionalized with dendritic polyglycerol (dPG) or dendritic polyglycerol sulfate (dPGS) are prepared. They are highly stable in aqueous solutions as well as physiological media. In particular, oleic acid capped iron oxide particles (core diameter = 11 +/- 1 nm) were modified by a ligand exchange process in a one pot synthesis with dPG and dPGS bearing phosphonate as anchor groups. Dynamic light scattering measurements performed in water and different biological media demonstrate that the hydrodynamic diameter of the particles is only slightly increased by the ligand exchange process resulting in a final diameter of less than 30 nm and that the particles are stable in these media. It is also revealed by magnetic resonance studies that their magnetic relaxivity is reduced by the surface modification but it is still sufficient for high contrast magnetic resonance imaging (MRI). Additionally, incubation of dPGS functionalized iron oxide nanoparticles with human umbilical vein endothelial cells showed a 50% survival at 85 nM (concentration of nanoparticles). Surface plasmon resonance (SPR) studies demonstrate that the dPGS functionalized iron oxide nanoparticles inhibit L-selectin ligand binding whereas the particles containing only dPG do not show this effect. Experiments in a flow chamber with human myelogenous leukemia cells confirmed L-selectin inhibition of the dPGS functionalized iron oxide nanoparticles and with that the L-selectin mediated leukocyte adhesion. These results indicate that dPGS functionalized iron oxide nanoparticles are a promising contrast agent for inflamed tissue probed by MRI. Electronic supplementary information (ESI) available: A detailed description of the synthesis of the ligands as well as the preparation and functionalization of the iron oxide nanoparticles including their physico-chemical characterization are presented. Further, details of the cell experiments and the SPR experiments are given. Two representative movies are provided showing leukocyte rolling on the ligand coated surface of the flow chamber. See DOI: 10.1039/c3nr04793h

Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

PubMed

Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

2015-05-18

Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell-delivered magnetic nanoparticles caused hyperthermia-mediated increased survival in a murine pancreatic cancer model

PubMed Central

Basel, Matthew T; Balivada, Sivasai; Wang, Hongwang; Shrestha, Tej B; Seo, Gwi Moon; Pyle, Marla; Abayaweera, Gayani; Dani, Raj; Koper, Olga B; Tamura, Masaaki; Chikan, Viktor; Bossmann, Stefan H; Troyer, Deryl L

2012-01-01

Using magnetic nanoparticles to absorb alternating magnetic field energy as a method of generating localized hyperthermia has been shown to be a potential cancer treatment. This report demonstrates a system that uses tumor homing cells to actively carry iron/iron oxide nanoparticles into tumor tissue for alternating magnetic field treatment. Paramagnetic iron/ iron oxide nanoparticles were synthesized and loaded into RAW264.7 cells (mouse monocyte/ macrophage-like cells), which have been shown to be tumor homing cells. A murine model of disseminated peritoneal pancreatic cancer was then generated by intraperitoneal injection of Pan02 cells. After tumor development, monocyte/macrophage-like cells loaded with iron/ iron oxide nanoparticles were injected intraperitoneally and allowed to migrate into the tumor. Three days after injection, mice were exposed to an alternating magnetic field for 20 minutes to cause the cell-delivered nanoparticles to generate heat. This treatment regimen was repeated three times. A survival study demonstrated that this system can significantly increase survival in a murine pancreatic cancer model, with an average post-tumor insertion life expectancy increase of 31%. This system has the potential to become a useful method for specifically and actively delivering nanoparticles for local hyperthermia treatment of cancer. PMID:22287840

A predictive model of iron oxide nanoparticles flocculation tuning Z-potential in aqueous environment for biological application

NASA Astrophysics Data System (ADS)

Baldassarre, Francesca; Cacciola, Matteo; Ciccarella, Giuseppe

2015-09-01

Iron oxide nanoparticles are the most used magnetic nanoparticles in biomedical and biotechnological field because of their nontoxicity respect to the other metals. The investigation of iron oxide nanoparticles behaviour in aqueous environment is important for the biological applications in terms of polydispersity, mobility, cellular uptake and response to the external magnetic field. Iron oxide nanoparticles tend to agglomerate in aqueous solutions; thus, the stabilisation and aggregation could be modified tuning the colloids physical proprieties. Surfactants or polymers are often used to avoid agglomeration and increase nanoparticles stability. We have modelled and synthesised iron oxide nanoparticles through a co-precipitation method, in order to study the influence of surfactants and coatings on the aggregation state. Thus, we compared experimental results to simulation model data. The change of Z-potential and the clusters size were determined by Dynamic Light Scattering. We developed a suitable numerical model to predict the flocculation. The effects of Volume Mean Diameter and fractal dimension were explored in the model. We obtained the trend of these parameters tuning the Z-potential. These curves matched with the experimental results and confirmed the goodness of the model. Subsequently, we exploited the model to study the influence of nanoparticles aggregation and stability by Z-potential and external magnetic field. The highest Z-potential is reached up with a small external magnetic influence, a small aggregation and then a high suspension stability. Thus, we obtained a predictive model of Iron oxide nanoparticles flocculation that will be exploited for the nanoparticles engineering and experimental setup of bioassays.

High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

NASA Astrophysics Data System (ADS)

Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

2016-06-01

Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI). Electronic supplementary information (ESI) available: Detailed IONP synthetic methods, description of magnetic particle relaxometer set-up, TEM of reference IONP (Senior Scientific PrecisionMRX™ 25 nm oleic acid-coated nanoparticles), concentration dependent PSF of all IONP samples, PSF and SAR of Zn-Sph and Zn-Cube mixture sample, upper right quadrant of field-dependent hysteresis curve labelled with static field strengths, and the magnetic hyperthermia temperature profiles with and without the presence of external magnetic fields. See DOI: 10.1039/c6nr01877g

Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

NASA Astrophysics Data System (ADS)

Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

2017-04-01

We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

Dispersion of iron nano-particles on expanded graphite for the shielding of electromagnetic radiation

NASA Astrophysics Data System (ADS)

Xu, Zheng; Huang, Yu'an; Yang, Yang; Shen, Jianyi; Tang, Tao; Huang, Runsheng

2010-10-01

Composite materials containing electrically conductive expanded graphite (EG) and magnetic iron nano-particles for electromagnetic shielding were prepared by impregnating EG with an ethanol solution containing iron nitrate and acetic acid, followed by drying and reduction in H 2. Magnetic nano-iron particles were found to be highly dispersed on the surface of EG in the Fe/EG composites, and played the role of enhancing the electromagnetic shielding effectiveness (SE) at low frequencies (0.3-10 MHz), which seemed to depend proportionally on magnetic hysteresis loss of loaded iron nano-particles.

Integration of organohalide-respiring bacteria and nanoscale zero-valent iron (Bio-nZVI-RD): A perfect marriage for the remediation of organohalide pollutants?

PubMed

Wang, Shanquan; Chen, Siyuan; Wang, Yu; Low, Adrian; Lu, Qihong; Qiu, Rongliang

2016-12-01

Due to massive production and improper handling, organohalide compounds are widely distributed in subsurface environments, primarily in anoxic groundwater, soil and sediment. Compared to traditional pump-and-treat or dredging-and-disposal treatments, in situ remediation employing abiotic or biotic reductive dehalogenation represents a sustainable and economic solution for the removal of organohalide pollutants. Both nanoscale zero-valent iron (nZVI) and organohalide-respiring bacteria remove halogens through reductive dehalogenation and have been extensively studied and successfully applied for the in situ remediation of chloroethenes and other organohalide pollutants. nZVI and microbial reductive dehalogenation (Bio-RD) complement each other to boost reductive dehalogenation efficiency, suggesting that the integration of nZVI with Bio-RD (Bio-nZVI-RD) may constitute an even more promising strategy for the in situ remediation of organohalide pollutants. In this review, we first provide an overview of the current literature pertaining to nZVI- and organohalide-respiring bacteria-mediated reductive dehalogenation of organohalide pollutants and compare the pros and cons of individual treatment methods. We then highlight recent studies investigating the implementation of Bio-nZVI-RD to achieve rapid and complete dehalogenation and discuss the halogen removal mechanism of Bio-nZVI-RD and its prospects for future remediation applications. In summary, the use of Bio-nZVI-RD facilitates opportunities for the effective in situ remediation of a wide range of organohalide pollutants. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and Characterization of Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron (nZVI/rGO) Composites Used for Pb(II) Removal

PubMed Central

Fan, Mingyi; Li, Tongjun; Hu, Jiwei; Cao, Rensheng; Wu, Qing; Wei, Xionghui; Li, Lingyun; Shi, Xuedan; Ruan, Wenqian

2016-01-01

Reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites were prepared by chemical deposition method and were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, N2-sorption and X-ray photoelectron spectroscopy (XPS). Operating parameters for the removal process of Pb(II) ions, such as temperature (20–40 °C), pH (3–5), initial concentration (400–600 mg/L) and contact time (20–60 min), were optimized using a quadratic model. The coefficient of determination (R2 > 0.99) obtained for the mathematical model indicates a high correlation between the experimental and predicted values. The optimal temperature, pH, initial concentration and contact time for Pb(II) ions removal in the present experiment were 21.30 °C, 5.00, 400.00 mg/L and 60.00 min, respectively. In addition, the Pb(II) removal by nZVI/rGO composites was quantitatively evaluated by using adsorption isotherms, such as Langmuir and Freundlich isotherm models, of which Langmuir isotherm gave a better correlation, and the calculated maximum adsorption capacity was 910 mg/g. The removal process of Pb(II) ions could be completed within 50 min, which was well described by the pseudo-second order kinetic model. Therefore, the nZVI/rGO composites are suitable as efficient materials for the advanced treatment of Pb(II)-containing wastewater. PMID:28773813

Artificial Neural Network Modeling and Genetic Algorithm Optimization for Cadmium Removal from Aqueous Solutions by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron (nZVI/rGO) Composites

PubMed Central

Fan, Mingyi; Li, Tongjun; Hu, Jiwei; Cao, Rensheng; Wei, Xionghui; Shi, Xuedan; Ruan, Wenqian

2017-01-01

Reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites were synthesized in the present study by chemical deposition method and were then characterized by various methods, such as Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nZVI/rGO composites prepared were utilized for Cd(II) removal from aqueous solutions in batch mode at different initial Cd(II) concentrations, initial pH values, contact times, and operating temperatures. Response surface methodology (RSM) and artificial neural network hybridized with genetic algorithm (ANN-GA) were used for modeling the removal efficiency of Cd(II) and optimizing the four removal process variables. The average values of prediction errors for the RSM and ANN-GA models were 6.47% and 1.08%. Although both models were proven to be reliable in terms of predicting the removal efficiency of Cd(II), the ANN-GA model was found to be more accurate than the RSM model. In addition, experimental data were fitted to the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. It was found that the Cd(II) adsorption was best fitted to the Langmuir isotherm. Examination on thermodynamic parameters revealed that the removal process was spontaneous and exothermic in nature. Furthermore, the pseudo-second-order model can better describe the kinetics of Cd(II) removal with a good R2 value than the pseudo-first-order model. PMID:28772901

Membrane Alterations in Pseudomonas putida F1 Exposed to Nanoscale Zerovalent Iron: Effects of Short-Term and Repetitive nZVI Exposure.

PubMed

Kotchaplai, Panaya; Khan, Eakalak; Vangnai, Alisa S

2017-07-18

In this study, we report the effect of the commercial nanoscale zerovalent iron (nZVI) on environmental bacteria, emphasizing the importance of nZVI-bacterial membrane interaction on nZVI toxicity as well as the adaptability of bacteria to nZVI. Exposure of Pseudomonas putida F1 to 0.1, 1.0, and 5.0 g/L of nZVI caused the reduction in colony forming units (CFUs) substantially for almost 3 orders of magnitude. However, a rebound in the cell number was observed after the prolonged exposure except for 5.0 g/L nZVI at which bacterial viability was completely inhibited. Upon exposure, nZVI accumulated on and penetrated into the bacterial cell membrane. Cell membrane composition analysis revealed the conversion of the cis to trans isomer of unsaturated fatty acid upon short-term nZVI exposure, resulting in a more rigid membrane counteracting the membrane-fluidizing effect of nZVI. Several cycles of repetitive exposure of cells to 0.1 g/L nZVI induced a persistent phenotype of P. putida F1 as indicated by smaller colony morphology, a more rigid membrane, and higher tolerance to nZVI. A low interaction between nZVI particles and the surface of the nZVI-persistent phenotypic cells reduced the nZVI-induced membrane damage. This study unveils the significance of nZVI-membrane interaction on toxicity of nZVI toward bacteria.

Synthesis and Characterization of Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron (nZVI/rGO) Composites Used for Pb(II) Removal.

PubMed

Fan, Mingyi; Li, Tongjun; Hu, Jiwei; Cao, Rensheng; Wu, Qing; Wei, Xionghui; Li, Lingyun; Shi, Xuedan; Ruan, Wenqian

2016-08-12

Reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites were prepared by chemical deposition method and were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, N₂-sorption and X-ray photoelectron spectroscopy (XPS). Operating parameters for the removal process of Pb(II) ions, such as temperature (20-40 °C), pH (3-5), initial concentration (400-600 mg/L) and contact time (20-60 min), were optimized using a quadratic model. The coefficient of determination ( R ² > 0.99) obtained for the mathematical model indicates a high correlation between the experimental and predicted values. The optimal temperature, pH, initial concentration and contact time for Pb(II) ions removal in the present experiment were 21.30 °C, 5.00, 400.00 mg/L and 60.00 min, respectively. In addition, the Pb(II) removal by nZVI/rGO composites was quantitatively evaluated by using adsorption isotherms, such as Langmuir and Freundlich isotherm models, of which Langmuir isotherm gave a better correlation, and the calculated maximum adsorption capacity was 910 mg/g. The removal process of Pb(II) ions could be completed within 50 min, which was well described by the pseudo-second order kinetic model. Therefore, the nZVI/rGO composites are suitable as efficient materials for the advanced treatment of Pb(II)-containing wastewater.

Mapping fracture flow paths with a nanoscale zero-valent iron tracer test and a flowmeter test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Chiu, Yung-Chia; Teng, Mao-Hua; Liou, Sofia Ya Hsuan

2018-02-01

The detection of preferential flow paths and the characterization of their hydraulic properties are important for the development of hydrogeological conceptual models in fractured-rock aquifers. In this study, nanoscale zero-valent iron (nZVI) particles were used as tracers to characterize fracture connectivity between two boreholes in fractured rock. A magnet array was installed vertically in the observation well to attract arriving nZVI particles and identify the location of the incoming tracer. Heat-pulse flowmeter tests were conducted to delineate the permeable fractures in the two wells for the design of the tracer test. The nZVI slurry was released in the screened injection well. The arrival of the slurry in the observation well was detected by an increase in electrical conductivity, while the depth of the connected fracture was identified by the distribution of nZVI particles attracted to the magnet array. The position where the maximum weight of attracted nZVI particles was observed coincides with the depth of a permeable fracture zone delineated by the heat-pulse flowmeter. In addition, a saline tracer test produced comparable results with the nZVI tracer test. Numerical simulation was performed using MODFLOW with MT3DMS to estimate the hydraulic properties of the connected fracture zones between the two wells. The study results indicate that the nZVI particle could be a promising tracer for the characterization of flow paths in fractured rock.

Dynamic study of Cr(VI) removal performance and mechanism from water using multilayer material coated nanoscale zerovalent iron.

PubMed

Wu, Bin; Peng, Dinghua; Hou, Siyu; Tang, Bicong; Wang, Can; Xu, Heng

2018-05-16

In this study, the dynamic Cr(VI) removal process from water by the synthesized multilayer material coated nanoscale zerovalent iron (SBC-nZVI) was systematically discussed at different treatment conditions. The results showed that initial pH, contact time, Cr(VI) concentration and the dosage of SBC-nZVI were important parameters that influenced the Cr(VI) removal efficiency. The major Cr(VI) removal occurred within 60 min and gradually tend to equilibrium with consistent treatment. The removal efficiency was highly depended on pH values and the adsorption kinetics agreed well with the pseduo-second-order model (PSO). When the initial Cr(VI) concentration was below 15 mg/L, the removal rate could reach to about 100%. Moreover, the removal efficiency increased with the increase of SBC-nZVI dosage, which related to the increase of reactive sites. To understand the removal mechanism, SBC-nZVI before and after reaction with Cr(VI) were characterized by fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). These analysis showed that the interaction of SBC-nZVI with Cr(VI) was mainly controlled by reduction and electrostatic attraction. Therefore, these results explained the interaction between Cr(VI) and SBC-nZVI material in detail, and further proved that SBC-nZVI could be an effective material to remove Cr(VI) from water. Copyright © 2018. Published by Elsevier Ltd.

Removal of polycyclic aromatic hydrocarbons (PAHs) from textile dyeing sludge by ultrasound combined zero-valent iron/EDTA/Air system.

PubMed

Man, Xiaoyuan; Ning, Xun-An; Zou, Haiyuan; Liang, Jieying; Sun, Jian; Lu, Xingwen; Sun, Jiekui

2018-01-01

This paper proposes a combined ultrasound (US) and zero-valent iron/EDTA/Air (ZEA) system to remove polycyclic aromatic hydrocarbons (PAHs) from textile dyeing sludge. The removal efficiencies of 16 PAHs using ZEA, US/Air (air injected into the US process), and US/ZEA treatments were investigated, together with the effects of various operating parameters. The enhanced mechanisms of US and the role of reactive oxygen species (ROS) in removing PAHs in the US/ZEA system were explored. Results showed that only 42.5% and 32.9% of ∑16 PAHs were removed by ZEA and US/Air treatments respectively, whereas 70.1% were removed by US/ZEA treatment, (with favorable operating conditions of 2.0 mM EDTA, 15 g/L ZVI, and 1.08 w/cm 3 ultrasonic density). The US/ZEA system could be used with a wide pH range. US led to synergistic improvement of PAHs removal in the ZEA system by enhancing sludge disintegration to release PAHs and promoting ZVI corrosion and oxygen activation. In the US/ZEA system, PAHs could be degraded by ROS (namely OH, O 2 - /HO 2 , and Fe(IV)) and adsorbed by ZVI, during which the ROS made the predominant contribution. This study provides important insights into the application of a US/ZEA system to remove PAHs from sludge. Copyright © 2017 Elsevier Ltd. All rights reserved.

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

NASA Astrophysics Data System (ADS)

Mines, Paul D.; Kaarsholm, Kamilla M. S.; Droumpali, Ariadni; Andersen, Henrik R.; Lee, Wontae; Hwang, Yuhoon

2017-09-01

Remediation of contaminated groundwater by nanoscale zero-valent iron (nZVI) is widely becoming a leading environmentally friendly solution throughout the globe. Since a wide range of various nZVI-containing materials have been developed for effective remediation, it is necessary to determine an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical strategies in order to terminate nZVI reactivity without altering the concentration of volatile compounds in the solution. The strategies include surface passivation in alkaline conditions by addition of carbonate, and consumption of nZVI by a reaction competitor. Four halogenated chemicals, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we report the simple and effective method to terminate the reactivity of nZVI by addition of a reducing reactivity competitor.

Effect of anions and humic acid on the performance of nanoscale zero-valent iron particles coated with polyacrylic acid.

PubMed

Kim, Hong-Seok; Ahn, Jun-Young; Kim, Cheolyong; Lee, Seockheon; Hwang, Inseong

2014-10-01

Effects of anions (NO3(-), HCO3(-), Cl(-), SO4(2-)) and humic acid on the reactivity and core/shell chemistries of polyacrylic acid-coated nanoscale zero-valent iron (PAA-NZVI) and inorganically modified NZVI (INORG-NZVI) particles were investigated. The reactivity tests under various ion concentrations (0.2-30mN) revealed the existence of a favorable molar ratio of anion/NZVI that increased the reactivity of NZVI particles. The presence of a relatively small amount of humic acid (0.5mgL(-1)) substantially decreased the INORG-NZVI reactivity by 76%, whereas the reactivity of PAA-NZVI decreased only by 12%. The XRD and TEM results supported the role of the PAA coating of PAA-NZVI in impeding the oxidation of the Fe(0) core by groundwater solutes. This protective role provided by the organic coating also resulted in a 2.3-fold increase in the trichloroethylene (TCE) reduction capacity of PAA-NZVI compared to that of INORG-NZVI in the presence of anions/humic acid. Ethylene and ethane were simultaneously produced as the major reduction products of TCE in both NZVI systems, suggesting that a hydrodechlorination occurred without the aid of metallic catalysts. The PAA coating, originally designed to improve the mobility of NZVI, enhanced TCE degradation performances of NZVI in the presence of anions and humic acid. Copyright © 2014 Elsevier Ltd. All rights reserved.

Artificial Neural Network Modeling and Genetic Algorithm Optimization for Cadmium Removal from Aqueous Solutions by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron (nZVI/rGO) Composites.

PubMed

Fan, Mingyi; Li, Tongjun; Hu, Jiwei; Cao, Rensheng; Wei, Xionghui; Shi, Xuedan; Ruan, Wenqian

2017-05-17

Reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites were synthesized in the present study by chemical deposition method and were then characterized by various methods, such as Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nZVI/rGO composites prepared were utilized for Cd(II) removal from aqueous solutions in batch mode at different initial Cd(II) concentrations, initial pH values, contact times, and operating temperatures. Response surface methodology (RSM) and artificial neural network hybridized with genetic algorithm (ANN-GA) were used for modeling the removal efficiency of Cd(II) and optimizing the four removal process variables. The average values of prediction errors for the RSM and ANN-GA models were 6.47% and 1.08%. Although both models were proven to be reliable in terms of predicting the removal efficiency of Cd(II), the ANN-GA model was found to be more accurate than the RSM model. In addition, experimental data were fitted to the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. It was found that the Cd(II) adsorption was best fitted to the Langmuir isotherm. Examination on thermodynamic parameters revealed that the removal process was spontaneous and exothermic in nature. Furthermore, the pseudo-second-order model can better describe the kinetics of Cd(II) removal with a good R² value than the pseudo-first-order model.

Influence of permeability on nanoscale zero-valent iron particle transport in saturated homogeneous and heterogeneous porous media.

PubMed

Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

2016-09-01

Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important role in successful and efficient remediation, especially in heterogeneous systems. Initial sand permeability (k 0) influences on spatial particle distributions were investigated and quantified in homogeneous and heterogeneous systems within the presented study. Four homogeneously filled column experiments and a heterogeneously filled tank experiment, using different median sand grain diameters (d 50), were performed to determine if NZVI particles were transported into finer sand where contaminants could be trapped. More NZVI particle retention, less particle transport, and faster decrease in k were observed in the column studies using finer sands than in those using coarser sands, reflecting a function of k 0. In heterogeneous media, NZVI particles were initially transported and deposited in coarse sand areas. Increasing the retained NZVI mass (decreasing k in particle deposition areas) caused NZVI particles to also be transported into finer sand areas, forming an area with a relatively homogeneous particle distribution and converged k values despite the different grain sizes present. The deposited-particle surface area contribution to the increasing of the matrix surface area (θ) was one to two orders of magnitude higher for finer than coarser sand. The dependency of θ on d 50 presumably affects simulated k changes and NZVI distributions in numerical simulations of NZVI injections into heterogeneous aquifers. The results implied that NZVI can in principle also penetrate finer layers.

Ligand-assisted degradation of carbon tetrachloride by microscale zero-valent iron.

PubMed

Zhang, Xianlan; Deng, Baolin; Guo, Jing; Wang, Yang; Lan, Yeqing

2011-04-01

Degradation of carbon tetrachloride (CT) by microscale zero-valent iron (ZVI) was investigated in batch systems with or without organic ligands (ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, malic acid and oxalic acid) at pHs from 3.5 to 7.5. The results demonstrated that at 25°C, the dechlorination of CT by microscale ZVI is slow in the absence of organic ligands, with a pseudo-first-order rate constant of 0.0217 h(-1) at pH 3.5 and being further dropped to 0.0052 h(-1) at pH 7.5. However, addition of organic ligands significantly enhanced the rates and the extents of CT removal, as indicated by the rate constant increases of 39, 31, 32, 28 and 18 times in the presence of EDTA, citric acid, tartaric acid, malic acid and oxalic acid, respectively, at pH 3.5 and 25°C. The effect of EDTA was most significant; the dechlorination of CT at an initial concentration of 20 mg l(-1) increased from 16.3% (no ligands) to 89.1% (with EDTA) at the end of 8h reaction. The enhanced CT degradation in the presence of organic ligands was primarily attributed to the elimination of a surface passivation layer of Fe(III) (hydr)oxides on the microscale ZVI through chelating of organic ligands with Fe(III), which maintained the exposure of active sites on ZVI surface to CT. Copyright © 2010 Elsevier Ltd. All rights reserved.

An Aspergillus aculateus strain was capable of producing agriculturally useful nanoparticles via bioremediation of iron ore tailings.

PubMed

Bedi, Ankita; Singh, Braj Raj; Deshmukh, Sunil K; Adholeya, Alok; Barrow, Colin J

2018-06-01

Mining waste such as iron ore tailing is environmentally hazardous, encouraging researchers to develop effective bioremediation technologies. Among the microbial isolates collected from iron ore tailings, Aspergillus aculeatus (strain T6) showed good leaching efficiency and produced iron-containing nanoparticles under ambient conditions. This strain can convert iron ore tailing waste into agriculturally useful nanoparticles. Fourier-transform Infrared Spectroscopy (FT-IR analysis) established the at the particles are protein coated, with energy dispersive X-ray Spectroscopy (EDX analysis) showing strong signals for iron. Transmission Electron Microscopy (TEM analysis) showed semi-quasi spherical particles having average size of 15 ± 5 nm. These biosynthesized nanoparticles when tested for their efficacy on seed emergence activity of mungbean (Vigna radiata) seeds, and enhanced plant growth at 10 and 20 ppm. Copyright © 2018 Elsevier Ltd. All rights reserved.

SERS-active silver nanoparticle aggregates produced in high-iron float glass by ion exchange process

NASA Astrophysics Data System (ADS)

Karvonen, L.; Chen, Y.; Säynätjoki, A.; Taiviola, K.; Tervonen, A.; Honkanen, S.

2011-11-01

Silver nanoparticles were produced in iron containing float glasses by silver-sodium ion exchange and post-annealing. In particular, the effect of the concentration and the oxidation state of iron in the host glass on the nanoparticle formation was studied. After the nanoparticle fabrication process, the samples were characterized by optical absorption measurements. The samples were etched to expose nanoparticle aggregates on the surface, which were studied by optical microscopy and scanning electron microscopy. The SERS-activity of these glass samples was demonstrated and compared using a dye molecule Rhodamine 6G (R6G) as an analyte. The importance of the iron oxidation level for reduction process is discussed. The glass with high concentration of Fe 2+ ions was found to be superior in SERS applications of silver nanoparticles. The optimal surface features in terms of SERS enhancement are also discussed.

Missing Fe: hydrogenated iron nanoparticles

NASA Astrophysics Data System (ADS)

Bilalbegović, G.; Maksimović, A.; Mohaček-Grošev, V.

2017-03-01

Although it was found that the FeH lines exist in the spectra of some stars, none of the spectral features in the interstellar medium (ISM) have been assigned to this molecule. We suggest that iron atoms interact with hydrogen and produce Fe-H nanoparticles which sometimes contain many H atoms. We calculate infrared spectra of hydrogenated iron nanoparticles using density functional theory methods and find broad, overlapping bands. Desorption of H2 could induce spinning of these small Fe-H dust grains. Some of hydrogenated iron nanoparticles possess magnetic and electric moments and should interact with electromagnetic fields in the ISM. FenHm nanoparticles could contribute to the polarization of the ISM and the anomalous microwave emission. We discuss the conditions required to form FeH and FenHm in the ISM.

Time-resolved laser-induced incandescence characterization of metal nanoparticles

NASA Astrophysics Data System (ADS)

Sipkens, T. A.; Singh, N. R.; Daun, K. J.

2017-01-01

This paper presents a comparative analysis of time-resolved laser-induced incandescence measurements of iron, silver, and molybdenum aerosols. Both the variation of peak temperature with fluence and the temperature decay curves strongly depend on the melting point and latent heat of vaporization of the nanoparticles. Recovered nanoparticle sizes are consistent with ex situ analysis, while thermal accommodation coefficients follow expected trends with gas molecular mass and structure. Nevertheless, there remain several unanswered questions and unexplained behaviors: the radiative properties of laser-energized iron nanoparticles do not match those of bulk molten iron; the absorption cross sections of molten iron and silver at the excitation laser wavelength exceed theoretical predictions; and there is an unexplained feature in the temperature decay of laser-energized molybdenum nanoparticles immediately following the laser pulse.

Multi-component Fe–Ni hydroxide nanocatalyst for oxygen evolution and methanol oxidation reactions under alkaline conditions

DOE PAGES

Candelaria, Stephanie L.; Bedford, Nicholas M.; Woehl, Taylor J.; ...

2016-11-29

Here, iron-incorporated nickel-based materials show promise as catalysts for the oxygen evolution reac-tion (OER) half-reaction of water electrolysis. Nickel has also exhibited high catalytic activity for methanol oxidation, particularly when in the form of a bimetallic catalyst. In this work, bimetallic iron-nickel nanoparticles were synthesized using a multi-step procedure in water under ambient conditions. When compared to monometallic iron and nickel nanoparticles, Fe-Ni nanoparticles show enhanced catalytic activity for both OER and methanol oxidation under alkaline conditions. At 1 mA/cm 2, the overpotential for monometallic iron and nickel nanoparticles was 421 mV and 476 mV, respectively, while the bimetallic Fe-Nimore » nanoparticles had a greatly reduced overpotential of 256 mV. At 10 mA/cm 2, bimetallic Fe-Ni nanoparticles had an overpotential of 311 mV. Spec-troscopy characterization suggests that the primary phase of nickel in Fe-Ni nanoparticles is the more disordered alpha phase of nickel hydroxide.« less

Stability of polyelectrolyte-coated iron nanoparticles for T2-weighted magnetic resonance imaging

NASA Astrophysics Data System (ADS)

McGrath, Andrew J.; Dolan, Ciaran; Cheong, Soshan; Herman, David A. J.; Naysmith, Briar; Zong, Fangrong; Galvosas, Petrik; Farrand, Kathryn J.; Hermans, Ian F.; Brimble, Margaret; Williams, David E.; Jin, Jianyong; Tilley, Richard D.

2017-10-01

Iron nanoparticles are highly-effective magnetic nanoparticles for T2 magnetic resonance imaging (MRI). However, the stability of their magnetic properties is dependent on good protection of the iron core from oxidation in aqueous media. Here we report the synthesis of custom-synthesized phosphonate-grafted polyelectrolytes (PolyM3) of various chain lengths, for efficient coating of iron nanoparticles with a native iron oxide shell. The size of the nanoparticle-polyelectrolyte assemblies was investigated by transmission electron microscopy and dynamic light scattering, while surface attachment was confirmed by Fourier transform infrared spectroscopy. Low cytotoxicity was observed for each of the nanoparticle-polyelectrolyte ("Fe-PolyM3") assemblies, with good cell viability (>80%) remaining up to 100 μg mL-1 Fe in HeLa cells. When applied in T2-weighted MRI, corresponding T2 relaxivities (r2) of the Fe-PolyM3 assemblies were found to be dependent on the chain length of the polyelectrolyte. A significant increase in contrast was observed when polyelectrolyte chain length was increased from 6 to 65 repeating units, implying a critical chain length required for stabilization of the α-Fe nanoparticle core.

Peptide-functionalized magnetic nanoparticles for cancer therapy applications

NASA Astrophysics Data System (ADS)

Hauser, Anastasia Kruse

Lung cancer is one of the leading causes of cancer deaths in the United States. Radiation and chemotherapy are conventional treatments, but they result in serious side effects and the probability of tumor recurrence remains high. Therefore, there is an increasing need to enhance the efficacy of conventional treatments. Magnetic nanoparticles have been previously studied for a variety of applications such as magnetic resonance imaging contrast agents, anemia treatment, magnetic cell sorting and magnetically mediated hyperthermia (MMH). In this work, dextran coated iron oxide nanoparticles were developed and functionalized with peptides to target the nanoparticles to either the extracellular matrix (ECM) of tumor tissue or to localize the nanoparticles in subcellular regions after cell uptake. The magnetic nanoparticles were utilized for a variety of applications. First, heating properties of the nanoparticles were utilized to administer hyperthermia treatments combined with chemotherapy. The nanoparticles were functionalized with peptides to target fibrinogen in the ECM and extensively characterized for their physicochemical properties, and MMH combined with chemotherapy was able to enhance the toxicity of chemotherapy. The second application of the nanoparticles was magnetically mediated energy delivery. This treatment does not result in a bulk temperature rise upon actuation of the nanoparticles by an alternating magnetic field (AMF) but rather results in intracellular damage via friction from Brownian rotation or nanoscale heating effects from Neel relaxations. The nanoparticles were functionalized with a cell penetrating peptide to facilitate cell uptake and lysosomal escape. The intracellular effects of the internalized nanoparticles alone and with activation by an AMF were evaluated. Iron concentrations in vivo are highly regulated as excess iron can catalyze the formation of the hydroxyl radical through Fenton chemistry. Although often a concern of using iron oxide nanoparticles for therapeutic applications, these inherent toxicities were harnessed and utilized to enhance radiation therapy. Therefore, the third application of magnetic nanoparticles was their ability to catalyze reactive oxygen species formation and increase efficacy of radiation. Overall, iron oxide nanoparticles have a variety of cancer therapy applications and are a promising class of materials for increasing efficacy and reducing the side effects of conventional cancer treatments. Keywords: iron oxide nanoparticles, peptides, magnetically mediated hyperthermia, magnetically mediated energy delivery, reactive oxygen species.

Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine

PubMed Central

Bao, Yuping; Wen, Tianlong; Samia, Anna Cristina S.; Khandhar, Amit; Krishnan, Kannan M.

2015-01-01

We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body –– an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field. PMID:26586919

Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine.

PubMed

Bao, Yuping; Wen, Tianlong; Samia, Anna Cristina S; Khandhar, Amit; Krishnan, Kannan M

2016-01-01

We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body -- an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field.

Iron oxide and gold nanoparticles in cancer therapy

NASA Astrophysics Data System (ADS)

Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

2016-08-01

Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

Nanoscale zero valent supported by Zeolite and Montmorillonite: Template effect of the removal of lead ion from an aqueous solution.

PubMed

Arancibia-Miranda, Nicolás; Baltazar, Samuel E; García, Alejandra; Muñoz-Lira, Daniela; Sepúlveda, Pamela; Rubio, María A; Altbir, Dora

2016-01-15

In this work, we have studied the Pb(2+) sorption capacity of Zeolite (Z) and Montmorillonite (Mt) functionalized with nanoscale zero-valent iron (nZVI), at 50% w/w, obtained by means of an impregnating process with a solvent excess. The composites were characterized by several techniques including X-ray diffraction; scanning electron microscopy (SEM); BET area; isoelectric point (IEP); and, finally a magnetic response. Comparatively significant differences in terms of electrophoretic and magnetic characteristics were found between the pristine materials and the composites. Both structures show a high efficiency and velocity in the removal of Pb(2+) up to 99.0% (200.0 ppm) after 40 min of reaction time. The removal kinetics of Pb(2+) is adequately described by the pseudo second-order kinetic model, and the maximum adsorbed amounts (q(e)) of this analyte are in close accordance with the experimental results. The intraparticle diffusion model shows that this is not the only rate-limiting step, this being the Langmuir model which was well adjusted to our experimental data. Therefore, maximum sorption capacities were found to be 115.1±11.0, 105.5±9.0, 68.3±1.3, 54.2±1.3, and 50.3±4.2 mg g(-1), for Mt-nZVI, Z-nZVI, Zeolite, Mt, and nZVI, respectively. The higher sorption capacities can be attributed to the synergetic behavior between the clay and iron nanoparticles, as a consequence of the clay coating process with nZVI. These results suggest that both composites could be used as an efficient adsorbent for the removal of lead from contaminated water sources. Copyright © 2015 Elsevier B.V. All rights reserved.

Regenerability of hydrotalcite-derived nickel-iron alloy nanoparticles for syngas production from biomass tar.

PubMed

Li, Dalin; Koike, Mitsuru; Wang, Lei; Nakagawa, Yoshinao; Xu, Ya; Tomishige, Keiichi

2014-02-01

Nickel-iron/magnesium/aluminum bimetallic catalysts were prepared by the calcination and reduction of nickel-magnesium-iron-aluminum hydrotalcite-like compounds. Characterization suggests that, at iron/nickel≤0.5, both nickel and iron species are homogeneously distributed in the hydrotalcite precursor and incorporated into the Mg(Ni, Fe, Al)O periclase after calcination, giving rise to uniform nickel-iron alloy nanoparticles after reduction. Ni-Fe/Mg/Al (Fe/Ni=0.25) exhibits the best catalytic performance for the steam reforming of tar derived from the pyrolysis of biomass. It is suggested that the uniform nickel-iron alloy nanoparticles and the synergy between nickel and iron are responsible for the high catalytic performance. Moreover, the Ni-Fe/Mg/Al catalyst exhibits much better regenerability toward oxidation-reduction treatment for the removal of deposited coke than that of conventional Ni-Fe/α-Al2 O3 . This property can be attributed to the better regeneration of Ni-Fe alloy nanoparticles through the formation and reduction of Mg(Ni, Fe, Al)O. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Human health risk assessment for nanoparticle-contaminated aquifer systems.

PubMed

Tosco, Tiziana; Sethi, Rajandrea

2018-08-01

Nanosized particles (NPs), such as TiO 2 , Silver, graphene NPs, nanoscale zero-valent iron, carbon nanotubes, etc., are increasingly used in industrial processes, and releases at production plants and from landfills are likely scenarios for the next years. As a consequence, appropriate procedures and tools to quantify the risks for human health associated to these releases are needed. The tiered approach of the standard ASTM procedure (ASTM-E2081-00) is today the most applied for human health risk assessment at sites contaminated by chemical substances, but it cannot be directly applied to nanoparticles: NP transport along migration pathways follows mechanisms significantly different from those of chemicals; moreover, also toxicity indicators (namely, reference dose and slope factor) are NP-specific. In this work a risk assessment approach modified for NPs is proposed, with a specific application at Tier 2 to migration in groundwater. The standard ASTM equations are modified to include NP-specific transport mechanisms. NPs in natural environments are typically characterized by a heterogeneous set of NPs having different size, shape, coating, etc. (all properties having a significant impact on both mobility and toxicity). To take into account this heterogeneity, the proposed approach divides the NP population into classes, each having specific transport and toxicity properties, and simulates them as independent species. The approach is finally applied to a test case simulating the release of heterogeneous Silver NPs from a landfill. The results show that taking into account the size-dependent mobility of the particles provides a more accurate result compared to the direct application of the standard ASTM procedure. In particular, the latter tends to underestimate the overall toxic risk associated to the nP release. Copyright © 2018 Elsevier Ltd. All rights reserved.

The effects of metallic engineered nanoparticles upon plant systems: An analytic examination of scientific evidence.

PubMed

Tolaymat, Thabet; Genaidy, Ash; Abdelraheem, Wael; Dionysiou, Dionysios; Andersen, Christian

2017-02-01

Recent evidence for the effects of metallic engineered nanoparticles (ENPs) on plants and plant systems was examined together with its implications for other constituents of the Society-Environment-Economy (SEE) system. In this study, we were particularly interested to determine whether or not metallic ENPs have both stimulatory and inhibitory effects upon plant performance. An emphasis was made to analyze the scientific evidence on investigations examining both types of effects in the same studies. Analysis of evidence demonstrated that metallic ENPs have both stimulatory and inhibitory effects mostly in well-controlled environments and soilless media. Nano zero-valent iron (nZVI) and Cu ENPs have potential for use as micronutrients for plant systems, keeping in mind the proper formulation at the right dose for each type of ENP. The concentration levels for the stimulatory effects of Cu ENPs are lower than for those for nZVI. Newer findings showed that extremely smaller concentrations of Au ENPs (smaller than those for nZVI and Cu ENPs) induce positive effects for plant growth, which is attributed to effects on secondary metabolites. Ag ENPs have demonstrated their usage as antimicrobial/pesticidal agents for plant protection; however, precautions should be taken to avoid higher concentrations not only for plant systems, but also, other constituents in the SEE. Further research is warranted to investigate the stimulatory and inhibitory effects of metallic ENPs in soil media in order to broaden the horizon of sustainable agriculture production in terms of higher and safer yields so as to meet the food requirements of human population. Copyright © 2016. Published by Elsevier B.V.