Activation process of air stable nanoscale zero-valent iron particles

Ribas, David López; Černík, Miroslav; Benito, J.A.; Filip, Jan; Martí, Vicenç

doi:10.1016/j.cej.2017.03.056

Cited by 34 publications

(41 citation statements)

References 47 publications

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“…Ribas (2017) reported that dry, bare NZVI particles are highly reactive and are pyrophoric when in contact with air. Current trends in NZVI manufacturing lead to surface passivation of dry NZVI particles with a thin oxide layer, resulting in a decrease in their reactivity 35 . The addition of carriers such as powdered activated carbon to NZVI to produce NZVI/GAC reduces the decrease in surface energy and reactivity of NZVI and increases the yield.…”

Section: Resultsmentioning

confidence: 99%

Chromium ion removal from raw water by magnetic iron composites and Shewanella oneidensis MR-1

Zhang

et al. 2019

Sci Rep

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In this study, nanoiron active carbon composites (NZVI/GAC) were used to remove chromium ions from raw water. The composites were synthesized from a novel formula of biological activated carbon and characterized by various techniques. The adsorption test data were fit by a pseudo-second-order kinetic model and Langmuir model. The q e and R 2 values were 187 mg Cr/g and 0.9960, respectively, with 0.2 g/L NZVI/GAC at an initial concentration of 118 mg/L Cr according to the Langmuir isotherm model. Moreover, a Cr 6+ detoxification reactor was constructed with the magnetic iron composite. The results indicated that the synthesized magnetic iron composite was a significant adsorbent for Cr 6+ removal from aqueous solutions. The detoxification reactor was able to remove Cr 6+ from raw water at an initial concentration of 26.5 mg/L within a short time period (3–5 min), with a removal efficiency of up to 99.90% and a treatment capacity of 45.0 mg Cr 6+ /g of adsorbent; the Cr 6+ concentrations in the outflow met the GB5749–2006 requirements for drinking water. A synergistic effect between NZVI/GAC and a suspension of the bacterium Shewanella oneidensis MR-1 was found, showing that this bacterium can be used as a regeneration agent for iron-depleted activated carbon materials.

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Section: Resultsmentioning

confidence: 99%

Chromium ion removal from raw water by magnetic iron composites and Shewanella oneidensis MR-1

Zhang

et al. 2019

Sci Rep

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“…Unfortunately, these reports co-exist in the literature with publications demonstrating that Fe 0 surface is universally covered by oxide layers [61][62][63][64][65][66], and that Fe 0 is additionally passivated with corrosion products during the remediation process [44,52,61,67,68]. Numerous recent studies, aimed to gain insight into the principles governing the removal of Cr VI in Fe 0 /H 2 O systems, have also presumed that this process is exclusively the result of direct electron transfer from Fe 0 to Cr VI [69][70][71][72][73][74][75][76][77][78][79]. Since the surface of commercially Fe 0 materials is permanently covered by an outer layer of low electric conductive air-formed oxides (hematite, maghemite) [64], the electron transport from Fe 0 to Cr VI should be severely inhibited [69][70][71][72][73][74][75][76][77][78][79].…”

Section: More Recent Laboratory-scale Reports (Post Elisabeth City Prb)mentioning

confidence: 99%

“…Numerous recent studies, aimed to gain insight into the principles governing the removal of Cr VI in Fe 0 /H 2 O systems, have also presumed that this process is exclusively the result of direct electron transfer from Fe 0 to Cr VI [69][70][71][72][73][74][75][76][77][78][79]. Since the surface of commercially Fe 0 materials is permanently covered by an outer layer of low electric conductive air-formed oxides (hematite, maghemite) [64], the electron transport from Fe 0 to Cr VI should be severely inhibited [69][70][71][72][73][74][75][76][77][78][79]. Moreover, Fe 0 efficiency should significantly decrease during the time, as its surface is progressively covered with additional secondary mineral coatings that prevents penetration of the Cr VI and stops the electron transfer [11,[80][81][82].…”

Section: More Recent Laboratory-scale Reports (Post Elisabeth City Prb)mentioning

confidence: 99%

Progress in Understanding the Mechanism of CrVI Removal in Fe0-Based Filtration Systems

Gheju¹

2018

Water

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Hexavalent chromium (Cr VI ) compounds are used in a variety of industrial applications and, as a result, large quantities of Cr VI have been released into the environment due to inadequate precautionary measures or accidental releases. Cr VI is highly toxic to most living organisms and a known human carcinogen by inhalation route of exposure. Another major issue of concern about Cr VI compounds is their high mobility, which easily leads to contamination of surface waters, soil, and ground waters. In recent years, attention has been focused on the use of metallic iron (Fe 0 ) for the abatement of Cr VI polluted waters. Despite a great deal of research, the mechanisms behind the efficient aqueous Cr VI removal in the presence of Fe 0 (Fe 0 /H 2 O systems) remain deeply controversial. The introduction of the Fe 0 -based filtration technology, at the beginning of 1990s, was coupled with the broad consensus that direct reduction of Cr VI by Fe 0 was followed by co-precipitation of resulted cations (Cr III , Fe III ). This view is still the dominant removal mechanism (reductive-precipitation mechanism) within the Fe 0 remediation industry. An overview on the literature on the Cr geochemistry suggests that the reductive-precipitation theory should never have been adopted. Moreover, recent investigations recalling that a Fe 0 /H 2 O system is an ion-selective one in which electrostatic interactions are of primordial importance is generally overlooked. The present work critically reviews existing knowledge on the Fe 0 /Cr VI /H 2 O and Cr VI /H 2 O systems, and clearly demonstrates that direct reduction with Fe 0 followed by precipitation is not acceptable, under environmental relevant conditions, as the sole/main mechanism of Cr VI removal in the presence of Fe 0 .

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“…Initially, to prepare the nZVI slurry, 250 g of nZVI particles were mixed to 1000 mL of deionized water to check the slurry's consistency. After this, the preparation was done to fill a 5000 mL container at a final w/w Fe to water ratio of 0.25 [27]. The Fe 0 content in the slurry was measured to be 93%, based on the amount of hydrogen gas emitted when iron nanoparticles react at a volumetric volume of 60% with the addition of sulfuric acid [28].…”

Section: Materials and Initial Experimentsmentioning

confidence: 99%

Enriched Co-Treatment of Pharmaceutical and Acidic Metal-Containing Wastewater with Nano Zero-Valent Iron

2021

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Among traditional hazardous waste sources, pharmaceutical-containing wastewater and acidic mine drainage need treatment to preserve the expected water supply quality. A nano zero-valent iron (nZVI)-enriched treatment of these two streams is evaluated for simultaneous removal of various heavy metal ions, organic pollutants, sulfates, the efficiency of the treatment system, and separation of reaction products in the fluidized-bed reactor. The reactor packed with silica sand was inoculated with sludge from an anaerobic digester, then 1–3 g/L of nZVI slurry added to cotreat a hospital feed and acid mine wastewater at 5:2 v/v. The biotreatment process is monitored through an oxidation–reduction potential (Eh) for 90 days. The removal pathway for the nZVI used co-precipitation, sorption, and reduction. The removal load for Zn and Mn was approximately 198 mg Zn/g Fe and 207 mg Mn/g Fe, correspondingly; achieving sulfate (removal efficiency of 94% and organic matter i.e., chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved organic carbon (DOC), total dissolved nitrogen (TDN) reduced significantly, but ibuprofen and naproxen achieved 31% and 27% removal, respectively. This enriched cotreatment system exhibited a high reducing condition in the reactor, as confirmed by Eh; hence, the nZVI was dosed only a few times in biotreatment duration, demonstrating a cost-effective system.

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Activation process of air stable nanoscale zero-valent iron particles

Cited by 34 publications

References 47 publications

Chromium ion removal from raw water by magnetic iron composites and Shewanella oneidensis MR-1

Chromium ion removal from raw water by magnetic iron composites and Shewanella oneidensis MR-1

Progress in Understanding the Mechanism of CrVI Removal in Fe0-Based Filtration Systems

Enriched Co-Treatment of Pharmaceutical and Acidic Metal-Containing Wastewater with Nano Zero-Valent Iron

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