Colloidal Stability and Mobility of Extracellular Polymeric Substance Amended Hematite Nanoparticles

Narvekar, Sneha Pradip; Ritschel, Thomas; Totsche, Kai Uwe

doi:10.2136/vzj2017.03.0063

Cited by 16 publications

(11 citation statements)

References 65 publications

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“…Thus, large quartz particles might be scavengers for otherwise colloidally stable claysized particles by net attractive forces if the surfaces were not screened by organic compounds such as EPS ( Figure 5). The immobilization of colloidal haematite particles on an oppositely charged porous quartz media surface was also shown by Narvekar, Ritschel, and Totsche (2017) if the haematite particles were not coated with EPS. The formation of these mineral-mineral CBUs is relevant for initial and OMdepleted soils characterized by mineral MFMs obtained from bedrock or pedogenic formation.…”

Section: Formation Of Mineral-mineral Associationsmentioning

confidence: 93%

“…As a result, all particles were net-negatively charged in the EPS-containing treatment at the experimental pH, resulting in effective repulsion and a colloidally stable suspension. Therefore, the CBUs formed were mobile in porous media, as also illustrated by Narvekar et al (2017) for haematite covered with EPS that impeded any attractive forces to glass porous media. At the field scale, such conditions could lead to an export of organo-mineral CBUs with the seepage water (e.g.…”

Section: Surface Propertiesmentioning

confidence: 97%

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Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

Guhra

Ritschel

Totsche

2019

European J Soil Science

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Structures of colloidal compounds in soil, including organo–mineral and mineral–mineral associations, are considered as composite building units (CBUs) that may combine into soil microaggregates. Despite the ubiquitous occurrence of CBUs, the major formation mechanisms are rather obscure and little is known about whether they form primarily during weathering of the parent rocks or by aggregation processes from the soil suspension. We studied the formation of CBUs from suspensions composed of minerals and organic matter typical for temperate soils (i.e. quartz, goethite, illite and extracellular polymeric substances [EPS]). Without EPS, we found CBUs formed as mineral–mineral associations by hetero coagulation of illite and quartz that is bridged by goethite. The presence of EPS, in contrast, led to the formation of a stable suspension of clay‐sized CBUs with no involvement of quartz. We explained this by the rapid formation of organo–mineral CBUs made of EPS‐associated goethite and EPS‐associated illite. The sorption of EPS to goethite screened its surface charge, thereby reducing the electrostatic attraction between goethite and illite. This interaction effectively impeded the formation of mineral–mineral CBUs. Moreover, interactions of EPS with goethite resulted in a marked decrease of the phosphorus/carbon ratio in the suspension. This suggested a preferred adsorption of phosphorus‐containing EPS constituents to goethite and in turn to a compositional fractionation of EPS constituents between the solid and liquid phase as shown by Fourier‐transform infrared spectroscopy with attenuated total reflection (FTIR–ATR). Laser light diffraction measurements revealed a shift from the fine silt fraction to that of the fine sand that also supports the role of EPS as a ‘binding’ agent. Highlights Composite building units (CBUs) form in suspensions with different mineral and organic components. Both, hetero mineral–mineral and organo–mineral CBUs were formed. The initial composition of the suspension controls type and properties of resulting CBUs. Depending on the mineral surfaces, EPS may serve as a separation or binding agent.

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Section: Formation Of Mineral-mineral Associationsmentioning

confidence: 93%

Section: Surface Propertiesmentioning

confidence: 97%

Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

Guhra

Ritschel

Totsche

2019

European J Soil Science

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“…Aggregation and charging behaviors of colloidal/nano particles have been investigated by time-resolved dynamic light scattering and electrophoretic light scattering techniques [9,18,19,20,22,27,28,29,30,31,32,33].…”

Section: Methodsmentioning

confidence: 99%

The effect of monovalent anion species on the aggregation and charging of allophane clay nanoparticles

Takeshita

Masuda

Kobayashi

2019

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Besides OM-mediated electron transfer, changes in iron (oxyhydr-)oxide crystallinity, and scavenging of biogenic Fe(II), OM may also affect the aggregation properties of iron (oxyhydr-)oxides. 72,73 This effect is relevant considering the inverse correlation of Fe(III) reduction by Geobacter metallireducens vs aggregate size. 9 Based on the following observations, we could not find such a relation in our study: (i) Initially, OM-free Fh was dispersed and composed of aggregates with sizes mainly <10 nm (Figure S8).…”

Section: T H I S C O N T E N T Imentioning

confidence: 99%

Organic Matter from Redoximorphic Soils Accelerates and Sustains Microbial Fe(III) Reduction

Fritzsche

Bosch

Sander

et al. 2021

Environ. Sci. Technol.

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Microbial reduction of Fe(III) minerals is a prominent process in redoximorphic soils and is strongly affected by organic matter (OM). We herein determined the rate and extent of microbial reduction of ferrihydrite (Fh) with either adsorbed or coprecipitated OM by Geobacter sulfurreducens. We focused on OM-mediated effects on electron uptake and alterations in Fh crystallinity. The OM was obtained from anoxic soil columns (effluent OM, efOM) and includedunlike waterextractable OMcompounds released by microbial activity under anoxic conditions. We found that organic molecules in efOM had generally no or only very low electron-accepting capacity and were incorporated into the Fh aggregates when coprecipitated with Fh. Compared to OM-free Fh, adsorption of efOM to Fh decelerated the microbial Fe(III) reduction by passivating the Fh surface toward electron uptake. In contrast, coprecipitation of Fh with efOM accelerated the microbial reduction, likely because efOM disrupted the Fh structure, as noted by Mossbauer spectroscopy. Additionally, the adsorbed and coprecipitated efOM resulted in a more sustained Fe(III) reduction, potentially because efOM could have effectively scavenged biogenic Fe(II) and prevented the passivation of the Fh surface by the adsorbed Fe(II). Fe(III)−OM coprecipitates forming at anoxic−oxic interfaces are thus likely readily reducible by Fe(III)-reducing bacteria in redoximorphic soils.

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Colloidal Stability and Mobility of Extracellular Polymeric Substance Amended Hematite Nanoparticles

Cited by 16 publications

References 65 publications

Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

Formation of mineral–mineral and organo–mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances

The effect of monovalent anion species on the aggregation and charging of allophane clay nanoparticles

Organic Matter from Redoximorphic Soils Accelerates and Sustains Microbial Fe(III) Reduction

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