Synergism of citric acid and zero-valent iron on Cr(VI) removal from real contaminated soil by electrokinetic remediation

Zheng, Yuqi; Yan, Yujie; Yu, Lin; Li, Huilin; Jiao, Binquan; Shiau, Yan-Chyuan; Li, Dongwei

doi:10.1007/s11356-019-06820-5

Cited by 21 publications

(5 citation statements)

References 31 publications

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“…From th left side of Figure 2, it is obvious that the addition of CA contributes to enhance the re moval efficiency compared to the HCl control group, and the highest removal rate was up to 87% at pH 4. This result further confirms that the metal chelation produced by CA i greater than the resolution of H + at a certain concentration, thereby facilitating the remova of Cd 2+ [37]. As for pH, the pH of all the samples increased after the reaction as shown in the right part of Figure 2, and the pH of the HCl control group was slightly higher than that of the CA group [38].…”

Section: Effect Of Ca On the Removal Of CD 2+ From Water By Modified Nzvi Under Different Phsupporting

confidence: 70%

Remediation of Cd-Contaminated Soil by Modified Nanoscale Zero-Valent Iron: Role of Plant Root Exudates and Inner Mechanisms

Huang

Yang

Deng

et al. 2021

IJERPH

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In this study, the role of exogenous root exudates and microorganisms was investigated in the application of modified nanoscale zero-valent iron (nZVI) for the remediation of cadmium (Cd)-contaminated soil. In this experiment, citric acid (CA) was used to simulate root exudates, which were then added to water and soil to simulate the pore water and rhizosphere environment. In detail, the experiment in water demonstrated that low concentration of CA facilitated Cd removal by nZVI, while the high concentration achieved the opposite. Among them, CA can promote the adsorption of Cd not only by direct complexation with heavy metal ions, but also by indirect effect to promote the production of iron hydroxyl oxides which has excellent heavy metal adsorption properties. Additionally, the H+ dissociated from CA posed a great influence on Cd removal. The situation in soil was similar to that in water, where low concentrations of CA contributed to the immobilization of Cd by nZVI, while high concentrations promoted the desorption of Cd and the generation of CA–Cd complexes which facilitated the uptake of Cd by plants. As the reaction progressed, the soil pH and cation exchange capacity (CEC) increased, while organic matter (OM) decreased. Meanwhile, the soil microbial community structure and diversity were investigated by high-throughput sequencing after incubation with CA and nZVI. It was found that a high concentration of CA was not conducive to the growth of microorganisms, while CMC had the effect of alleviating the biological toxicity of nZVI.

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Section: Effect Of Ca On the Removal Of CD 2+ From Water By Modified Nzvi Under Different Phsupporting

confidence: 70%

Remediation of Cd-Contaminated Soil by Modified Nanoscale Zero-Valent Iron: Role of Plant Root Exudates and Inner Mechanisms

Huang

Yang

Deng

et al. 2021

IJERPH

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“…This is a major concern because the oxidized hexavalent form, Cr(VI), has a higher toxicity than the reduced, mostly immobile, trivalent form, Cr(III). Many in situ remediation technologies have been developed and applied in Cr(VI)‐contaminated groundwater sites, such as the use of permeable reactive (reductive) barriers (Wilkin et al 2005), application(s) of strong abiotic reductants to reduce and remove Cr(VI) from solution via precipitation (Vermeul et al 2004; Dresel et al 2008; Zhong et al 2009), bioreduction, phytoremediation (Shams et al 2010; Zheng et al 2020), and natural attenuation (Last et al 2015; Truex et al 2015). However, remediation of Cr‐contaminated sites remains challenging mainly because of the heterogeneity of subsurface Cr contamination; the occurrence of a variety of Cr‐containing phases that exhibit difficult‐to‐predict geochemical behavior; the presence of other redox‐sensitive co‐contaminants as part of a complex contaminant mixture; and the existence of hard‐to‐access subsurface locations, or concentrated vadose zone Cr hot spots, that serve as a continuous source of groundwater (GW) contamination.…”

Section: Introductionmentioning

confidence: 99%

Vadose Zone Soil Flushing for Chromium Remediation: A Laboratory Investigation to Support Field‐scale Application

Szecsody¹,

Emerson²,

Lawter³

et al. 2023

Groundwater Monitoring Rem

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Cr(VI) flushing from the vadose zone to the groundwater (with subsequent Cr(VI) removal in groundwater by pump‐and‐treat system) is a promising remedial technique that has recently been used at field scale. This laboratory study was conducted to provide the technical basis to design a field soil flushing strategy. The objectives were to (1) quantify the relationship between sediment Cr(VI) and Cr(III) mass and release rates and subsequent Cr(VI) leaching; (2) investigate different methodologies to maximize Cr(VI) leaching, and (3) investigate methods to minimize leaching of remaining residual Cr. Characterization of Cr‐contaminated sediments (Hanford Site, WA) exhibited Cr(VI) showed that leach rates that were correlated to different Cr surface phases. Sediments with low leachable Cr(VI) (<2 μg/g) leached Cr rapidly, so slow infiltration of water in a single pulse was sufficient to leach most Cr. In contrast, sediments with high Cr (2 to 200 μg/g) released some Cr(VI) quickly but 10 to 50% Cr(VI) slowly (tens to hundreds of hours). Efficient unsaturated leaching of these sediments required a different infiltration strategy that includes: multiple slow leach pulses with time between flushing cycles; the use of a surfactant to increase Cr leaching from low‐permeability zones, and the use of a reductant (Na‐dithionite or Ca‐polysulfide) in the final leach water was highly effective at decreasing residual Cr leaching. This study clearly demonstrated that the methodology of basing laboratory Cr flushing on parameters such as Cr release mass and rates could be used to improve the efficiency of soil flushing at field scale.

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“…There are several accepted methods for removing Cr(VI), which typically exists as highly soluble and toxic chromate anions (HCrO 4 – or Cr 2 O 7 2– ), from industrial wastewater: photocatalytic reduction, ,− chemical precipitation, electrokinetic remediation, membrane filtration, , and adsorption. − Among these methods, adsorption is especially appealing, as it is very effective at removing Cr(VI) . The adsorption process requires a solid surface (i.e., an adsorbent) with a large surface area for the species to be adsorbed (i.e., an adsorbate) to attach to, either by physical or chemical processes, for which in here, the use of a nanosized material will be beneficial for providing the surface area.…”

Section: Introductionmentioning

confidence: 99%

“…There are several accepted methods for removing Cr(VI), which typically exists as highly soluble and toxic chromate anions (HCrO 4 − or Cr 2 O 7 2− ), from industrial wastewater: photocatalytic reduction, 6,8−10 chemical precipitation, 11 electrokinetic remediation, 12 membrane filtration, 13,14 and adsorption. 15−17 Among these methods, adsorption is especially appealing, as it is very effective at removing Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Formation of Dense and High-Aspect-Ratio Iron Oxide Nanowires by Water Vapor-Assisted Thermal Oxidation and Their Cr(VI) Adsorption Properties

et al. 2021

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Coral-like and nanowire (NW) iron oxide nanostructures were produced at 700 and 800 °C, respectively, through thermal oxidation of iron foils in air- and water vapor-assisted conditions. Water vapor-assisted thermal oxidation at 800 °C for 2 h resulted in the formation of highly crystalline α-Fe2O3 NWs with good foil surface coverage, and we propose that their formation was due to a stress-driven surface diffusion mechanism. The Cr(VI) adsorption property of an aqueous solution on α-Fe2O3 NWs was also evaluated after a contact time of 90 min. The NWs had a removal efficiency of 97% in a 225 mg/L Cr(VI) solution (pH 2, 25 °C). The kinetic characteristic of the adsorption was fitted to a pseudo-second-order kinetic model, and isothermal studies indicated that the α-Fe2O3 NWs exhibited an adsorption capacity of 66.26 mg/g. We also investigated and postulated a mechanism of the Cr(VI) adsorption in an aqueous solution of α-Fe2O3 NWs.

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Synergism of citric acid and zero-valent iron on Cr(VI) removal from real contaminated soil by electrokinetic remediation

Cited by 21 publications

References 31 publications

Remediation of Cd-Contaminated Soil by Modified Nanoscale Zero-Valent Iron: Role of Plant Root Exudates and Inner Mechanisms

Remediation of Cd-Contaminated Soil by Modified Nanoscale Zero-Valent Iron: Role of Plant Root Exudates and Inner Mechanisms

Vadose Zone Soil Flushing for Chromium Remediation: A Laboratory Investigation to Support Field‐scale Application

Formation of Dense and High-Aspect-Ratio Iron Oxide Nanowires by Water Vapor-Assisted Thermal Oxidation and Their Cr(VI) Adsorption Properties

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