Effect of lactate, glycine, and citrate on the kinetics of montmorillonite dissolution

Ramos, M. Elena; Cappelli, Chiara; Rozalén, Marisa; Fiore, Saverio; Huertas, F. Javier

doi:10.2138/am.2011.3694

Cited by 27 publications

(15 citation statements)

References 51 publications

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“…More specific dissolution processes of silicates can develop when specific types of organic ligands occur in the solution. These effects were studied, for instance, by Ramos et al (2011), who defined a ligand‐promoted over the proton‐promoted dissolution process for silicates. Similarly, the inverse trend for As and Ca can be a simple dilution effect of sediment detrital carbonates, as these minerals have very low As.…”

Section: Results and Analysismentioning

confidence: 99%

Conceptual Model of Arsenic Mobility in the Shallow Alluvial Aquifers Near Venice (Italy) Elucidated Through Machine Learning and Geochemical Modeling

Libera

Pedretti

Tateo

et al. 2020

Water Resources Research

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This work proposed a novel method to elucidate the controls of As mobility in complex aquifers based on an unsupervised machine learning algorithm, Self-Organizing Map (SOM), and process-based geochemical modeling. The approach is tested in the shallow aquifers of the Venetian Alluvial Plain (VAP) near Venice, Italy, where As concentrations seasonally and locally exceed recommended drinking water limits. SOM was fed using information from two geochemical surveys on eight VAP boreholes, and continuous reading of hourly groundwater head levels and weekly geochemical analyses from three VAP boreholes between mid-October 2017 and end of January 2018. The SOM analysis is consistent with redox-controlled dissolution-precipitation hydrous ferric oxides (HFOs) as a key control of As mobility in the aquifer. Dissolved As is positively correlated to Fe and NH þ 4 and negatively to the oxidizing-reducing potential (ORP). Negative correlation between As and groundwater head levels suggests a redox control by rainfall-driven recharge, which adds oxidants to the aquifer while progressively attenuating As. This mechanism is tested using process-based geochemical modeling, which simulates different transport modalities of oxidants entering the aquifer. Starting from reducing aquifer conditions, the model reproduces correctly the observed ORP and the trends in As and Fe, when the function describing the occurrence of oxidizing events scales according to the temporal occurrence of rainfall events. Heterogeneity can strongly control the local-scale effectiveness of recharge as a natural As attenuating factor, requiring a different model analysis to be properly assessed and to be developed in a follow-up study.

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Section: Results and Analysismentioning

confidence: 99%

Conceptual Model of Arsenic Mobility in the Shallow Alluvial Aquifers Near Venice (Italy) Elucidated Through Machine Learning and Geochemical Modeling

Libera

Pedretti

Tateo

et al. 2020

Water Resources Research

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“…It is slightly less intense under moderately alkaline conditions where the Al(OH) 4 -species is dominant since pH ≥ 9.5. It is worth mentioning that in geochemistry montmorillonite dissolution is known to be more enhanced by citric acid than oxalic acid [46,47].…”

Section: Oxalic Acidmentioning

confidence: 99%

Interactions between hydrated cement paste and organic acids: Thermodynamic data and speciation modeling

Windt

Bertron

Larreur-Cayol

et al. 2015

Cement and Concrete Research

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Abstract.Interactions of short-chain organic acids with hydrated cement phases affect structure durability in the agro-food and nuclear waste industries but can also be used to modify cement properties. Most previous studies have been experimental, performed at fixed concentrations and pH, without quantitatively discriminating among polyacidity effects, or complexation and salt precipitation processes. This paper addresses such issues by thermodynamic equilibrium calculations for acetic, citric, oxalic, succinic acids and a simplified hydrated CEM-I. The thermodynamic constants collected from the literature allow the speciation to be modelled over a wide range of pH and concentrations. Citric and oxalic had a stronger chelating effect than acetic acid, while succinic acid was intermediate. Similarly, Ca-citrate and Ca-oxalate salts were more insoluble than Ca-acetate and Ca-succinate salts. Regarding aluminium complexation, hydroxyls, sulphates, and acid competition was highlighted. The exploration of acid mixtures showed the preponderant effect of oxalate and citrate over acetate and succinate.

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“…In addition, previous studies have observed that organic ligands can decrease particle size and increase surface area . Therefore, ligand-promoted dissolution of rNAu-2 (Figures and S9) may have decreased rNAu-2 particle size, thus enhancing the oxidation extent as well.…”

Section: Discussionmentioning

confidence: 81%

Promotion of Microbial Oxidation of Structural Fe(II) in Nontronite by Oxalate and NTA

Zhao

Jin

Sheng

et al. 2020

Environ. Sci. Technol.

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Iron redox cycling occurs extensively in soils and sediments. Previous research has focused on microbially mediated redox cycling of aqueous Fe. At circumneutral pH, most Fe occurs in solid phase, where Fe and organic ligands interact closely. However, the role of organic ligands in microbial oxidation of solid-phase Fe(II) is not well understood. Here, we incubated reduced nontronite NAu-2 (rNAu-2) with an iron-oxidizing bacterium and in the presence of oxalate and nitrilotriacetic acid. These ligands significantly enhanced the rate and extent of microbial oxidation of structural Fe(II) in rNAu-2. Aqueous and solid-phase analyses, coupled with biogeochemical modeling, revealed a pathway for ligand-enhanced bio-oxidation of solid-phase Fe(II): (1) dissolution of rNAu-2 to form aqueous Fe(II)−ligand complex;(2) bio-oxidation to Fe(III)−ligand complex; (3) rapid reduction of Fe(III)−ligand complex to Fe(II)−ligand complex by structural Fe(II) in rNAu-2. In this process, the Fe(II)−ligand and Fe(III)−ligand complexes effectively serve as electron shuttle to expand the bioavailable pool of solid-phase Fe(II). These results have important implications for a better understanding of the bioavailability and reactivity of solid-phase Fe pool in the environment.

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Effect of lactate, glycine, and citrate on the kinetics of montmorillonite dissolution

Cited by 27 publications

References 51 publications

Conceptual Model of Arsenic Mobility in the Shallow Alluvial Aquifers Near Venice (Italy) Elucidated Through Machine Learning and Geochemical Modeling

Conceptual Model of Arsenic Mobility in the Shallow Alluvial Aquifers Near Venice (Italy) Elucidated Through Machine Learning and Geochemical Modeling

Interactions between hydrated cement paste and organic acids: Thermodynamic data and speciation modeling

Promotion of Microbial Oxidation of Structural Fe(II) in Nontronite by Oxalate and NTA

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