The Effect of Aeration on Mn(II) Sorbed to Clay Minerals and Its Impact on Cd Retention

Groeningen, Natacha Van; Christl, Iso; Kretzschmar, Ruben

doi:10.1021/acs.est.0c05875

Cited by 19 publications

(4 citation statements)

References 54 publications

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“…During oxygenation, exchangeable Cd increased and both Fe mineral-bound Cd and PC-bound Cd decreased (Figure b), which might be partially ascribed to the decrease in pH (Figure S6). Previous studies demonstrated that the decrease of pH during oxygenation resulted in Cd release from Fe–Mn (oxyhydr)oxides, , and low pH decreased Cd adsorption on biochar . The structure of PC was analyzed after oxygenation.…”

Section: Resultsmentioning

confidence: 99%

“…Drainage of paddy soils during the grain filling period results in the mobilization of Cd in soils and subsequent accumulation of Cd in rice grain. Cd mobilization is attributed to either oxidative dissolution of Cd sulfides or a decrease of pH induced by the precipitation of Fe (oxyhydr)oxides. ,, As a consequence, many mitigation strategies are proposed to reduce Cd bioavailability, such as amendment of lime to improve soil pH, and prolonged the flooding time to reduce soil oxidation . Cd release is virtually due to the depletion of binding sites.…”

Section: Environmental Implicationsmentioning

confidence: 99%

“…Through root adsorption of mobile Cd, rice grains may accumulate Cd, up to 10 mg/g, causing great threats to human health. − Fe(III) (oxyhydr)oxides are abundant redox-active components in soils, acting as the major sorbents for reducing Cd mobility. − Agricultural soils usually undergo anoxic–oxic oscillations due to rainfall and irrigation, affecting the transformation of Fe(III) (oxyhydr)oxides and consequent Cd retention. − Under anoxic conditions, Fe(III) (oxyhydr)oxides can be reduced by serving as terminal electron acceptors for microbial respiration, resulting in the dissolution of Fe(III) (oxyhydr)oxides . The produced Fe(II) either precipitates with anions (e.g., PO 4 3– ) or reacts with short-range ordered Fe(III) (oxyhydr)oxides (e.g., ferrihydrite), producing a wide range of secondary Fe minerals such as vivianite (Fe 3 (PO 4 ) 2 ·8H 2 O), goethite (α-FeOOH), and magnetite (Fe 3 O 4 ), depending on geochemical conditions. − During reductive dissolution of Fe(III) (oxyhydr)oxides, associated Cd will be released into solution due to the loss of adsorption sites, while the newly formed secondary Fe minerals can re-adsorb Cd in solution but typically exhibit lower retention of Cd due to the decrease in the specific surface. − Shift of the environment from anoxic to oxic conditions leads to Fe(II) oxidation and Fe(III) precipitation, which will enhance the immobilization of Cd through adsorption or coprecipitation, but oxidation and hydrolysis of Fe results in the decrease of pH, reducing Cd adsorption on Fe(III) (oxyhydr)oxides. − Transformation of Fe(III) (oxyhydr)oxides play a great role in the fate of Cd; however, existing studies were conducted only under anoxic or oxic conditions, only a few studies have looked into anoxic–oxic redox cycles and their effect on the transformation of Fe(III) (oxyhydr)oxides on Cd retention.…”

Section: Introductionmentioning

confidence: 99%

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Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions

Chu

Chen

2023

Environ. Sci. Technol.

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Fe(III) (oxyhydr)oxides are ubiquitous in paddy soils and play a key role in Cd retention. Recent studies report that pyrogenic carbon (PC) may largely affect the microbial transformation processes of Fe(III) (oxyhydr)oxides, yet the impact of PC on the fate of Fe(III) (oxyhydr)oxide-associated Cd during redox fluctuations remains unclear. Here, we investigated the effects of PC on Cd retention during microbial (Shewanella oneidensis MR-1) transformation of Cd(II)-bearing ferrihydrite under varying redox conditions. The results showed that in the absence of PC, microbial reduction of ferrihydrite resulted in Cd release under anoxic conditions and Fe(II) oxidation by oxygen resulted in Cd retention under subsequent oxic conditions. The presence of PC facilitated microbial ferrihydrite reductive dissolution under anoxic conditions, promoted Fe(II) oxidative precipitation under oxic conditions, and inhibited Cd release under both anoxic and oxic conditions. The presence of PC and frequent shifts in redox conditions (i.e., redox cycling) inhibited the transformation of ferrihydrite to highly crystalline goethite and magnetite that exhibited less Cd adsorption. As a result, PC enhanced Cd retention by 41−59% and 55−77% after the redox shift and redox cycling, respectively, while in the absence of PC, Cd retention decreased by 5% after the redox shift and increased by 11% after redox cycling. Sequential extraction analysis revealed that 63−78% of Cd was associated with Fe minerals, while 3−12% of Cd was bound to PC, indicating that PC promoted Cd retention mainly through inhibiting ferrihydrite transformation. Our results demonstrate the great impacts of PC on improving Cd retention under dynamic redox conditions, which is essential for applying PC in remediating Cd-contaminated paddy soils.

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Section: Resultsmentioning

confidence: 99%

Section: Environmental Implicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions

Chu

Chen

2023

Environ. Sci. Technol.

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“…With the recent development of an atomic-resolution transmission electron microscope (AC-TEM) and X-ray absorption fine structure (XAFS), direct visualization of single atoms has become feasible and regular. − More adsorption dynamic details, which might be ignored with traditional empirical adsorption models, could be directly visible now. These advancements, together with other techniques, provide an excellent opportunity to directly visualize the adsorption behavior on a material surface and open a new era to study the adsorption dynamics on the material interface.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting

et al. 2022

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Langmuir adsorption model is a classic physical–chemical adsorption model and is widely used to describe the monolayer adsorption behavior at the material interface in environmental chemistry. Traditional adsorption dynamic modeling solely considered the surface physiochemical interaction between the adsorbent and adsorbate. The surface reaction dynamics resulting from the heterogeneous surface and intrinsic electronic structure of absorbents were rarely considered within the reported adsorption experiments. Herein, by employing the chlorine hybrid graphene oxide (GO-Cl) to adsorb Ag+ in an aqueous solution, complicated molecular dynamics significantly deviated from the monolayer adsorption mechanism, as suggested by Langmuir adsorption curve fitting, has been elucidated down to atomic scale. In the time-dependent Ag adsorption experiments, both Ag single atoms and Ag/AgCl nanoparticle heterostructures are observed to be formed sequentially on GO-Cl. These observations indicate that for the surface adsorption dynamics, not only the surface chemical adsorption process involved but also photoreduction and the C–Cl bond cleavage reaction has been heavily engaged within the GO-Cl interface, suggesting a much more complicated vision rather than the monolayered adsorption algorithm as derived from curve fitting. This study uses GO-Cl as a simple example to disclose the complicated adsorption dynamic process underneath Langmuir adsorption curve fitting. It advocates the necessity of imaging the interfacial atomic-scale dynamic structure with high-resolution microscopy techniques in modern adsorption studies, rather than simply explaining the adsorption dynamics relying on the curve fitting results due to the complicated physiochemical reactivity of the adsorbents.

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Tree-based machine learning models for enhanced large-scale soil Mn classification by integrating visible-near infrared spectroscopy

Qi,

Zhou,

Chen

et al. 2024

J Soils Sediments

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The Effect of Aeration on Mn(II) Sorbed to Clay Minerals and Its Impact on Cd Retention

Cited by 19 publications

References 54 publications

Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions

Pyrogenic Carbon Improves Cd Retention during Microbial Transformation of Ferrihydrite under Varying Redox Conditions

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting

Tree-based machine learning models for enhanced large-scale soil Mn classification by integrating visible-near infrared spectroscopy

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