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

Velimirović, Milica; Larsson, Per‐Olof; Simons, Queenie; Bastiaens, Leen

doi:10.1016/j.chemosphere.2013.07.034

Cited by 18 publications

(6 citation statements)

References 29 publications

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“…In an attempt to develop tests for reactivity characterization for Fe 0 materials used for groundwater remediation or water treatment screening, many research groups have used a comparative study based on contaminant removal in aqueous solution to validate their tests [18,19,22,38,54,55]. Table 5 gives some details about some of these researches.…”

Section: Comparing H 2 Production and Uranium Removalmentioning

confidence: 99%

Characterizing the Reactivity of Metallic Iron for Water Treatment: H2 Evolution in H2SO4 and Uranium Removal Efficiency

Ndé-Tchoupé

Gwenzi

et al. 2020

Water

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Metallic iron (Fe0) has been demonstrated as an excellent material for decentralized safe drinking water provision, wastewater treatment and environmental remediation. An open issue for all these applications is the rational material selection or quality assurance. Several methods for assessing Fe0 quality have been presented, but all of them are limited to characterizing its initial reactivity. The present study investigates H2 evolution in an acidic solution (pH 2.0) as an alternative method, while comparing achieved results to those of uranium removal in quiescent batch experiments at neutral pH values. The unique feature of the H2 evolution experiment is that quantitative H2 production ceased when the pH reached a value of 3.1. A total of twelve Fe0 specimens were tested. The volume of molecular H2 produced by 2.0 g of each Fe0 specimen in 560 mL H2SO4 (0.01 M) was monitored for 24 h. Additionally, the extent of U(VI) (0.084 mM) removal from an aqueous solution (20.0 mL) by 0.1 g of Fe0 was characterized. All U removal experiments were performed at room temperature (22 ± 2 °C) for 14 days. Results demonstrated the difficulty of comparing Fe0 specimens from different sources and confirmed that the elemental composition of Fe0 is not a stand-alone determining factor for reactivity. The time-dependent changes of H2 evolution in H2SO4 confirmed that tests in the neutral pH range just address the initial reactivity of Fe0 materials. In particular, materials initially reacting very fast would experience a decrease in reactivity in the long-term, and this aspect must be incorporated in designing novel materials and sustainable remediation systems. An idea is proposed that could enable the manufacturing of intrinsically long-term efficient Fe0 materials for targeted operations as a function of the geochemistry.

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Section: Comparing H 2 Production and Uranium Removalmentioning

confidence: 99%

Characterizing the Reactivity of Metallic Iron for Water Treatment: H2 Evolution in H2SO4 and Uranium Removal Efficiency

Ndé-Tchoupé

Gwenzi

et al. 2020

Water

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“…Specific surface areas of microparticles are generally lower than 2 m² g -1 (Wang and Zhang 1997;Lien and Zhang 2001). However, the reactivity is not only linked to the specific surface area but also the chemical composition and presence of impurities on the surface, such as carbon, oxygen, sulfur or boron content (Lin and Lo 2005;Velimirovic et al 2013aVelimirovic et al , 2017. Standardized experiments have shown that the specific reaction rate constant (k SA ) for COCs degradation with mZVI particles are in the same order of magnitude than those obtained with nZVI particles, while iron corrosion occurs slowly (Velimirovic et al 2013b(Velimirovic et al , 2014.…”

Section: Nanoscale and Microscale Particlesmentioning

confidence: 99%

In Situ Chemical Reduction of Chlorinated Organic Compounds

Rodrigues

Betelu

Colombano

et al. 2020

Applied Environmental Science and Engineering for a Sustainable Future

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Chlorinated organic compounds (COCs) are common anthropogenic contaminants of soil and groundwater. COCs were industrially produced for different applications, such as dry cleaning, degreasing, or as pesticides. The presence of COCs in the environment is a major concern because of their toxicity and persistence.The most widely used method for their remediation is the conventional pump-and-treat system. However, this technology can hardly achieve a complete remediation because of geological characteristics and the presence of pore space pollution/adsorbed pollution, leading to a residual saturation. Hence, in addition to the improvement of pump-and-treat systems, in situ chemical processes have been largely developed. These chemical processes involve the injection of chemical reagents for the removal of residual source pollution and/or the treatment of plume contamination. Chemical degradation of COCs can be achieved by oxidative or reductive processes. If chemical oxidation has been first developed for in situ application, chemical reduction is one of the most important emerging remediation techniques for COCs treatment. Due to the electronegative character of chlorine substituents, COCs can effectively be transformed via reductive pathways. Moreover, reductive dechlorination has shown higher efficiency on highly chlorinated compounds. This chapter focuses on the presentation of the chemical reduction of the most common COCs pollutants, followed by kinetic and mechanistic approaches related to the use of iron-based particles. Developments on in situ chemical reduction technologies in order to enhance remediation rates are also exposed. Influence of environmental conditions for in situ applications is then developed. Finally, a case study is presented.

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“…However, our results showed that the initial disappearance of HCA was not directly related to PCE production, as a 10-min shift was observed for PCE production irrespective of the amount of particles. This delay may indicate that HCA degradation initially involves nonreductive sorption on the Pd-mZVI/PLA/H 2 O system, which is generally linked to the carbon content on the particle surfaces (Lin and Lo 2005;Velimirovic et al 2013b). In addition, this induction period could be caused by the absence of active hydrogen species (H * ads ) on the Pd surface, as He et al (2018) suggested that the dechlorination process on Pd particles requires first their saturation by H * (formation of palladium hydride) before any dechlorination reaction.…”

Section: Effects Of Pd-mzvi Dosagementioning

confidence: 99%

Elucidating the dechlorination mechanism of hexachloroethane by Pd-doped zerovalent iron microparticles in dissolved lactic acid polymers using chromatography and indirect monitoring of iron corrosion

Rodrigues

Betelu

Colombano

et al. 2019

Environ Sci Pollut Res

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The degradation mechanism of the pollutant hexachloroethane (HCA) by a suspension of Pd-doped zero-valent iron microparticles (Pd-mZVI) in dissolved lactic acid polymers and oligomers (referred to as PLA), was investigated using gas chromatography and the indirect monitoring of iron corrosion by continuous measurements of pH, oxidation-reduction potential (ORP) and conductivity. The first experiments took place in the absence of HCA, to understand the evolution of the Pd-mZVI/PLA/H 2 O system. This showed that the evolution of pH, ORP and conductivity is related to changes in solution chemistry due to iron corrosion, and that the system is initially cathodically controlled by H + mass transport to Pd surfaces because of the presence of an extensive PLA layer. We then investigated the effects of Pd-mZVI particles, temperature, initial HCA concentration and PLA content on the Pd-mZVI/PLA/HCA/H 2 O system, to obtain a better understanding of the degradation mechanism. In all cases, HCA dechlorination first requires the production of atomic hydrogen H *involving the accumulation of tetrachloroethylene (PCE) as an intermediate-before its subsequent reduction to non-chlorinated C 2 and C 4 compounds. The ratio between Pd-mZVI dosage, initial HCA concentration and PLA content affects the rate of H * generation as well as the rate-determining step of the process. A pseudo-first-order equation can be applied when Pd-mZVI dosage is much higher than the theoretical stoichiometry (600 mg for [HCA] 0 = 5-20 mg L -1 ). Our results indicate that the HCA degradation mechanism includes mass transfer, sorption, surface reaction with H * , and desorption of the product.

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

Cited by 18 publications

References 29 publications

Characterizing the Reactivity of Metallic Iron for Water Treatment: H2 Evolution in H2SO4 and Uranium Removal Efficiency

Characterizing the Reactivity of Metallic Iron for Water Treatment: H2 Evolution in H2SO4 and Uranium Removal Efficiency

In Situ Chemical Reduction of Chlorinated Organic Compounds

Elucidating the dechlorination mechanism of hexachloroethane by Pd-doped zerovalent iron microparticles in dissolved lactic acid polymers using chromatography and indirect monitoring of iron corrosion

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