Quantification of pH-dependent speciation of organic compounds with spectroscopy and chemometrics

Ritschel, Thomas; Totsche, Kai Uwe

doi:10.1016/j.chemosphere.2016.12.145

Cited by 9 publications

(5 citation statements)

References 44 publications

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“…Fluorescence and IR spectra of CEM showed an apparent response to changes in the pH, as known for other types of OM (e.g., Mobed et al., 1996; Ritschel & Totsche, 2017). Typically, the signal intensity increases from low to high pH (e.g., Pullin & Cabaniss, 1995) for CEM's humic‐like fluorescence (C1 and C2).…”

Section: Discussionmentioning

confidence: 53%

“…The cleaned deposits were freeze‐dried before further use and investigated by ATR–FTIR and CHNSO elemental analysis (Euro EA CHNSO Elemental Analyzer, Eurovector). ATR–FTIR spectra obtained from solid phases were decomposed into compound spectra via positive matrix factorization (PMF) (Ritschel & Totsche, 2017). According to the number of expected sample constituents, two components were reconstructed to represent goethite and mucus.…”

Section: Methodsmentioning

confidence: 99%

“…The pH‐adjusted mucus solutions were further analyzed by UV–VIS absorption from 860 to 200 nm (Cary 50 conc, Agilent Technologies) and fluorescence excitation–emission matrices (EEMs) with an excitation wavelength of 230–400 nm and an emission wavelength of 300–600 nm (Cary Eclipse, Agilent Technologies). EEMs were evaluated and reconstructed by a four‐component parallel factor analysis (PARAFAC) (according to Bro, 1997; Ritschel & Totsche, 2017) using a non‐negativity constrained alternating least‐squares algorithm (Kim & Park, 2008). From each pH variant, an aliquot was freeze‐dried for ATR–FTIR investigation.…”

Section: Methodsmentioning

confidence: 99%

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The functional role of earthworm mucus during aggregation

Guhra,

Wonneberger,

Stolze

et al. 2023

J. Plant Nutr. Soil Sci.

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BackgroundSoil organisms influence pedogenesis on a molecular level through the production of biopolymers which interact with soil minerals depending on their molecular properties. Specifically, biopolymers impact structure formation by inhibiting aggregation as a separation agent or promoting aggregation as a bridging agent. Mucus is a biopolymer excreted by earthworms that consists mainly of proteins, polysaccharides, and, to a lesser extent, lipids. However, despite earthworms’ fundamental contribution to soil quality and structuring via bioturbation, the role of mucus in aggregation still has to be unraveled.AimsOur study explores the role of cutaneous earthworm mucus (CEM) of Lumbricus terrestris L. for the formation of organo–mineral associations and aggregates, a sub‐process of pedogenesis.MethodsWe conducted batch experiments with goethite and CEM at different pH values and varying CEM concentrations to form mucus–goethite associations. Employing the newly formed mucus–goethite associations, we explored the (homo‐/hetero‐)aggregation with quartz particles as a function of the loading of surfaces with mucus‐C and CEM concentrations in solution.ResultsOur results suggest that the molecular structure of CEM constituents (especially proteins) is sensitive to pH. We found that the adsorption of CEM to goethite depends on pH and concentration. Polysaccharides of CEM adsorbed preferentially under acidic conditions (pH 3) and at low CEM concentration (6 mg mucus‐C L–1). In contrast, stronger adsorption of proteins was observed at higher CEM concentrations (30 mg mucus‐C L–1). In subsequent aggregation experiments, the hetero‐aggregation rate of organo–mineral associations and quartz decreased at low C‐loadings. Conversely, the rate increased at high loadings compared to the CEM‐free reference. Furthermore, electrostatic/steric repulsion (separation agent) inhibited the aggregation between goethite particles at high CEM concentrations in the solution (mineral/mucus ratio of 17). However, at a low CEM supply (mineral/mucus ratio of >83), CEM took the role of a bridging agent.ConclusionsThe composition, function, and (im‐)mobilization of CEM and corresponding organo–mineral associations in earthworm‐influenced soil structures are shaped by the structure/reactivity of CEM affected by environmental parameters. Formation and aggregation of mucus–mineral associations contribute to nutrient/carbon storage and are involved in the structure formation in soil.

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Section: Discussionmentioning

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The functional role of earthworm mucus during aggregation

Guhra,

Wonneberger,

Stolze

et al. 2023

J. Plant Nutr. Soil Sci.

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“…It is well-known that protons can accelerate the dissolution of iron oxides . Moreover, pH can change the acid–base speciation of ligands − and, subsequently, their relative distribution between the ice bulk and liquid-like grain boundary region because of the change of the charge on ligand molecules, which should influence the iron oxide dissolution process. Therefore, the effects of pH on the dissolution of iron in aqueous and frozen solutions were additionally investigated for ascorbic acid, hydroxylamine, and iodide (see Figure ), which revealed distinguished and contrasting pH-dependent behaviors.…”

Section: Resultsmentioning

confidence: 99%

Ligand-Specific Dissolution of Iron Oxides in Frozen Solutions

Menacherry

Kim

Lee

et al. 2018

Environ. Sci. Technol.

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The freezing-enhanced dissolution of iron oxides by various ligands has been recently proposed as a new mechanism that may influence the supply of bioavailable iron in frozen environments. The ligand-induced dissolution of iron oxides is sensitively affected by the kind and concentration of ligands, pH, and kind of iron oxides. While most ligands are thought to be freeze-concentrated in the ice grain boundary region along with iron oxides to enhance the iron dissolution, this study found that some ligands, such as ascorbic acid, suppress the iron dissolution in frozen solution relative to that in aqueous solution. Such ligands are proposed to be preferentially incorporated in the ice lattice bulk and not freeze-concentrated in the liquid-like grain boundary. The experimental analysis estimated that the ionized forms of ligands (e.g., iodide ions) are hardly present in the ice bulk region (<3%) and enhance the iron dissolution in frozen solution (relative to that in aqueous solution), whereas some neutral ligands (e.g., undissociated ascorbic acid) are significantly trapped in the ice bulk (>50%) and suppress the iron dissolution compared to the aqueous counterpart. The present results reveal that the ligand-induced dissolution of iron oxide in frozen solution is not always enhanced relative to aqueous solution but depends upon the kind of ligand and experimental conditions.

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“…18 NDM, such as alcohols and organic acids, widely exists in wastewater. 19 However, to the best of our knowledge, the influence of NDM in the degradation of IBU during the UV/H 2 O 2 process is unclarified, especially the mechanism of the reactions involving NDM. In experimental investigation, it is difficult to estimate whether NDM participated in the degradation of IBU since the solvents usually contain NDM.…”

Section: Introductionmentioning

confidence: 94%

New insights into the degradation mechanism of ibuprofen in the UV/H₂O₂ process: role of natural dissolved matter in hydrogen transfer reactions

Ding,

Zhang,

Fang

et al. 2023

Phys. Chem. Chem. Phys.

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Quantification of pH-dependent speciation of organic compounds with spectroscopy and chemometrics

Cited by 9 publications

References 44 publications

The functional role of earthworm mucus during aggregation

The functional role of earthworm mucus during aggregation

Ligand-Specific Dissolution of Iron Oxides in Frozen Solutions

New insights into the degradation mechanism of ibuprofen in the UV/H₂O₂ process: role of natural dissolved matter in hydrogen transfer reactions

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Quantification of pH-dependent speciation of organic compounds with spectroscopy and chemometrics

Cited by 9 publications

References 44 publications

The functional role of earthworm mucus during aggregation

The functional role of earthworm mucus during aggregation

Ligand-Specific Dissolution of Iron Oxides in Frozen Solutions

New insights into the degradation mechanism of ibuprofen in the UV/H2O2 process: role of natural dissolved matter in hydrogen transfer reactions

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Product

Resources

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New insights into the degradation mechanism of ibuprofen in the UV/H₂O₂ process: role of natural dissolved matter in hydrogen transfer reactions