Evaluation of remediation of Cr(VI)-contaminated soils by calcium polysulfide: Long-term stabilization and mechanism studies

Hu, Siyang; Dong, Li; Man, Yidong; Wen, Yongyue; Huang, Chuan

doi:10.1016/j.scitotenv.2021.148140

Cited by 19 publications

(5 citation statements)

References 45 publications

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“…The abnormal paucity of SO 4 2– is incongruous with the prevalence of REDOX reactions on the surface of Cr 0.5 Fe 0.5 (OH) 3 , but it does correspond to the decrease in the proportion of Cr(VI). The anomalous decrease in both SO 4 2– and Cr(VI) percentage might be attributed to the competitive adsorption of a significant amount of instantaneously formed CrO 4 2– and SO 4 . − Both CrO 4 2– and SO 4 2– were desorbed from the surface of Cr 0.5 Fe 0.5 (OH) 3 . Subsequently, dissolved CrO 4 2– is reduced by dissolved sulfite under the catalysis of dissolved Fe(III) to form Cr(III) ions, which elucidates the notable release of Cr(III). SO 3 · − + SO 3 · − → normalS 2 normalO 6 2 − normalS 2 normalO 6 2 − + normalH 2 …”

Section: Resultsmentioning

confidence: 98%

“…Hexavalent chromium (Cr(VI)) is a primary hazardous contaminant in soil due to its high toxicity, strong solubility, and significant mobility. − A commonly employed remediation strategy for Cr(VI) contamination involves the reduction of Cr(VI) to less toxic Cr(III) precipitates through the use of reductants such as Fe(II), nZVI, CaS x , , FeS, − and FeS 2 . The primary Cr(III) precipitates resulting from the remediation of Cr(VI) are amorphous chromium hydroxide (Cr(OH) 3 ) and amorphous coprecipitation of Cr–Fe (Cr x Fe 1– x (OH) 3 ).…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, increasing attention has been paid to the rebound of Cr(VI) following remediation of Cr(VI)-contaminated soil. Strong reducing agents, such as polysulfide, , were utilized to maintain a relatively reductive environment in order to inhibit the rebound of Cr(VI) . In addition, the investigation into the rebound mechanism of Cr(VI) has been expanded to encompass radical reactions triggered by reducing agents, such as FeS and nZVI, or through exposure to visible light .…”

Section: Introductionmentioning

confidence: 99%

“…In fact, sulfite is widely present in soil, primarily due to bacterial growth on organosulfur compounds and chemolithotrophic growth on inorganic sulfur compounds . Additionally, the utilization of sulfur-containing reducing agents (such as Na 2 SO 3 , Na 2 S 2 O 4 , Na 2 S, FeS, , FeS 2 , and CaS x , ) significantly increases the sulfite content in soil. Our preliminary investigation revealed that the proportion of sulfite in total sulfur increased from 4.81% to 14.04% after 6 months of amorphous FeS 2 remediation .…”

Section: Introductionmentioning

confidence: 99%

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Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃

Li,

Chen,

Tian

et al. 2023

Environ. Sci. Technol.

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Cr(VI) rebound is the primary risk associated with the reduction remediation of Cr(VI)-contaminated soil. The potential impact of sulfites, which can be produced by microbial activities or originate from sulfur-containing remediation agents, on the Cr(VI) rebound in the vadose zone has been overlooked. When sulfites are present, the stability of Cr x Fe 1−x (OH) 3 is compromised and significantly inferior to that of Cr(OH) 3 , as demonstrated in this paper. First, Fe acts as a catalyst for the conversion of adsorbed sulfite to SO 4•− , which subsequently triggers the oxidation of Cr(III) and results in the rebound of Cr(VI). The heterogeneous catalysis by Fe on the surface of Cr x Fe 1−x (OH) 3 plays a predominant role, contributing to 78% of the actual oxidation of Cr(III) among all employed catalytic processes. The presence of ambient Cl − can exacerbate the rebound effect of Cr(VI) by promoting the generation of HOCl. Furthermore, a portion of released Cr(VI) was reduced to Cr(III) by dissolved sulfite in the presence of dissolved Fe as a catalyst, thereby increasing the dissolution and migration risk associated with Cr x Fe 1−x (OH) 3 . Hence, the presence of sulfites results in a significant increase in the Cr(VI) rebound and Cr(III) release from Cr x Fe 1−x (OH) 3 . This challenges the conventional understanding of the stability of Cr x Fe 1−x (OH) 3 .

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃

Li,

Chen,

Tian

et al. 2023

Environ. Sci. Technol.

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“…The chemical reduction method [6] is commonly employed to remediate Cr(VI)-contaminated soil, with the critical process involving the conversion of highly toxic Cr(VI) to Cr(III) precipitate via reduction reactions using reducing agents such as FeSO 4 [6,7], Fe 0 [8][9][10], and CaS 4 [11][12][13]. This method effectively diminishes the migration ability and bioavailability of Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Adsorption-Reduction Behavior of Cr(VI) by Ferrihydrite-Fulvic Acid Complexes with Different C/Fe Mole Ratios

Zhang,

Chen,

et al. 2023

Adsorption Science & Technology

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Ferrihydrite and fulvic acid are prevalent components of soils and can significantly influence the environmental behavior of Cr(VI) in these matrices. Prior research has investigated the sorption behavior of Cr(VI) by ferrihydrite and fulvic acid independently; however, the sorption-reduction capacity of Cr(VI) by the ferrihydrite-fulvic acid complex, which is ubiquitously present in soils, has been less explored. In this study, ferrihydrite-fulvic acid complexes (Fh-FA) with varying C/Fe mole ratios were synthesized, and the adsorption-reduction behaviors of Cr(VI) on Fh-FA were examined using batch experiments, FTIR, BET, XRD, SEM-EDS, and XPS. The results demonstrate that the pseudo-second-order kinetic model can accurately describe the adsorption process of Fh-FA on Cr(VI), which can be delineated into three stages: rapid adsorption (0-30 min), slow adsorption (30-120 min), and reaction equilibrium (>120 min). The adsorption of Cr(VI) on Fh-FA primarily occurs through chemisorption. FTIR and XPS analyses revealed that Cr(VI) is initially adsorbed by Fe-OH on the Fh-FA surface. However, as the C/Fe mole ratio of Fh-FA increases, more Fe-OH is complexed by -COOH from FA, resulting in a decrease in the adsorption capacity of Cr(VI) by Fh-FA. The number of phenolic hydroxyl groups from FA also increases, providing additional electrons to reduce Cr(VI) to Cr(III) with increasing C/Fe mole ratio. This study not only emphasizes the adsorption-reduction behavior of Cr(VI) by ferrihydrite-fulvic acid complexes but also uncovers the interplay between C/Fe mole ratios and Cr(VI) adsorption-reduction, contributing to a more comprehensive understanding of the relative roles of Fe hydroxides and natural organic matter in soil environments. These findings have significant implications for Cr(VI) management in soils, enhancing our capability to protect and sustain the environmental quality.

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Microbial electrochemical Cr(VI) reduction in a soil continuous flow system

Beretta,

Sangalli,

Sezenna

et al. 2024

Integr Envir Assess & Manag

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Microbial electrochemical technologies represent innovative approaches to contaminated soil and groundwater remediation and provide a flexible framework for removing organic and inorganic contaminants by integrating electrochemical and biological techniques. To simulate in situ microbial electrochemical treatment of groundwater plumes, this study investigates Cr(VI) reduction within a bioelectrochemical continuous flow (BECF) system equipped with soil‐buried electrodes, comparing it to abiotic and open‐circuit controls. Continuous‐flow systems were tested with two chromium‐contaminated solutions (20–50 mg Cr(VI)/L). Additional nutrients, buffers, or organic substrates were introduced during the tests in the systems. With an initial Cr(VI) concentration of 20 mg/L, 1.00 mg Cr(VI)/(L day) bioelectrochemical removal rate in the BECF system was observed, corresponding to 99.5% removal within nine days. At the end of the test with 50 mg Cr(VI)/L (156 days), the residual Cr(VI) dissolved concentration was two orders of magnitude lower than that in the open circuit control, achieving 99.9% bioelectrochemical removal in the BECF. Bacteria belonging to the orders Solirubrobacteriales, Gaiellales, Bacillales, Gemmatimonadales, and Propionibacteriales characterized the bacterial communities identified in soil samples; differently, Burkholderiales, Mycobacteriales, Cytophagales, Rhizobiales, and Caulobacterales characterized the planktonic bacterial communities. The complexity of the microbial community structure suggests the involvement of different microorganisms and strategies in the bioelectrochemical removal of chromium. In the absence of organic carbon, microbial electrochemical removal of hexavalent chromium was found to be the most efficient way to remove Cr(VI), and it may represent an innovative and sustainable approach for soil and groundwater remediation. Integr Environ Assess Manag 2024;00:1–17. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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Evaluation of remediation of Cr(VI)-contaminated soils by calcium polysulfide: Long-term stabilization and mechanism studies

Cited by 19 publications

References 45 publications

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃

Adsorption-Reduction Behavior of Cr(VI) by Ferrihydrite-Fulvic Acid Complexes with Different C/Fe Mole Ratios

Microbial electrochemical Cr(VI) reduction in a soil continuous flow system

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Evaluation of remediation of Cr(VI)-contaminated soils by calcium polysulfide: Long-term stabilization and mechanism studies

Cited by 19 publications

References 45 publications

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of CrxFe1–x(OH)3

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of CrxFe1–x(OH)3

Adsorption-Reduction Behavior of Cr(VI) by Ferrihydrite-Fulvic Acid Complexes with Different C/Fe Mole Ratios

Microbial electrochemical Cr(VI) reduction in a soil continuous flow system

Contact Info

Product

Resources

About

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃

Sulfite Poses a Risk of Hexavalent Chromium Rebound in Vadose Zone: A Challenge of the Stability of Cr_xFe_1–x(OH)₃