Well-Ordered Kaolinite in Siderite Concretions from the Brazil Formation, Western Indiana

Störr, Manfred; Murray, Haydn H.

doi:10.1346/ccmn.1986.0340612

Cited by 8 publications

(4 citation statements)

References 3 publications

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“…Comparison of diffractograms for untreated, air-dried samples (top pattern) against samples heated to 530C (lower patterns) shows a marked decrease in the (001) 7 A kaolin peak in the latter, suggesting destruction of this clay mineral due to low thermal stability. correlated with kaolin mineral crystallinity (Storr & Murray 1986;Wada & Kakuto 1983;Keller & Haenni 1978), although the inability to see wellcrystallized kaolinite in SEM analyses makes it difficult to confirm the presence of this mineral in the present study. However, as enhanced crystallinity is indicated by the high thermal stability of kaolin in the rhizosphere, two theories which may account for this observation are suggested.…”

Section: Degrees 20mentioning

confidence: 62%

Mineralogy of the rhizosphere in forest soils of the eastern United States

April

Keller

1990

Biogeochemistry

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Chemical and mineralogical studies of forest soils from six sites in the northeastern and southeastern United States indicate that soil in the immediate vicinity of roots and fine root masses may show marked differences in physical characteristics, mineralogy and weathering compared to the bulk of the forest soil. Examination of rhizosphere and rhizoplane soils revealed that mineral grains within these zones are affected mechanically, chemically and mineralogically by the invading root bodies. In SEM/EDS analyses, phyllosilicate grains adjacent to roots commonly aligned with their long axis tangential to the root surface. Numerous mineral grains were also observed for which the edge abutting a root surface was significantly more fractured than the rest of the grain. Both the alignment and fracturing of mineral grains by growing roots may influence pedogenic processes within the rhizosphere by exposing more mineral surface to weathering in the root-zone microenvironment. Chemical interactions between roots and rhizosphere minerals included precipitation of amorphous aluminium oxides, opaline and amorphous silica, and calcium oxalate within the cells of mature roots and possible preferential dissolution of mineral grains adjacent to root bodies. Mineralogical analyses using X-ray diffraction (XRD) techniques indicated that kaolin minerals in some rhizosphere samples had a higher thermal stability than kaolin in the surrounding bulk forest soil. In addition, XRD analyses of clay minerals from one of the southeastern sites showed abundant muscovite in rhizoplane soil adhering to root surfaces whereas both muscovite and degraded mica were present in the immediately surrounding rhizosphere soil. This difference in mineral assemblages may be due to either K-enrichment in rhizoplane soil solutions or the preferential dissolution of biotite at the root-soil interface.

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Section: Degrees 20mentioning

confidence: 62%

Mineralogy of the rhizosphere in forest soils of the eastern United States

April

Keller

1990

Biogeochemistry

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“…As known, the natural siderite often coexists with some silicate or aluminosilicate minerals. The presence of Si and Al was confirmed in our siderite sample by XRF (Table S1), indicating these coexisting minerals were also introduced and embedded into S 0 when preparing the SSCReF . Since S 0 was gradually consumed to drive denitrification, partially embedded minerals would dissociate from SSCReF, potentially explaining their appearance in flushed-out material.…”

Section: Resultsmentioning

confidence: 59%

“…Compared to the fillers in the form of a mixed packing of S 0 particles and iron-containing solids (e.g., zerovalent iron and siderite), SSCReF features the combination of different components into a single filler, which would be very simple and convenient for practical use without worrying about uneven compound distribution. Additionally, when employing natural ores as the source of Fe (II) (e.g., siderite), intergrowth veinstone and surrounding rock would be inevitably introduced, typically composed of nonreactive silicate or aluminosilicate minerals . In the mixed packing manner as reported previously, natural ores were broken into granules at the millimeter scale as the filler. , If a substantial portion of these granules comprises nonreactive impurities, they will remain within the system and form a ‘dead zone’, because the typical water flush intensity (tens meters per hour) in pack-bed reactors is much lower than the sedimentation velocity of such large granules (e.g., the sedimentation velocity of a SiO 2 particle with the size of 1 mm is roughly estimated as about 1500 m/h according to the Stokes formula; details can be found in SI-Text S4).…”

Section: Resultsmentioning

confidence: 99%

“…Additional costs and efforts related to the safe transportation, storage, and use of sulfur may restrict its engineering application. Second, as a natural ore, siderite always contains nonreactive impurities (e.g., up to 40% SiO 2 ) . After long-term operation, the accumulation of these nonreactive impurities in the system would occupy the effective volume and reduce the overall performance.…”

Section: Introductionmentioning

confidence: 99%

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Highly Efficient Coremoval of Nitrate and Phosphate Driven by a Sulfur-Siderite Composite Reactive Filler toward Secondary Effluent Polishing

Xu,

Sun,

Yao

et al. 2023

Environ. Sci. Technol.

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Reactive fillers consisting of reduced sulfur and iron species (SFe-ReFs) have received increasing attention in tertiary wastewater treatment for nitrate and phosphate coremoval. However, the existing SFe-ReFs suffer from either low performance (e.g., pyrrhotite and pyrite) or unsatisfactory use in terms of combustible risk and residual nonreactive impurities (e.g., sulfur mixing with natural iron ores). Here, we developed a new type of sulfur-siderite composite ReF (SSCReF) with a structure of natural siderite powders eventually embedded into sulfur. SSCReFs exhibited many excellent properties, including higher mechanical strengths and hardness and especially much poorer ignitability compared to pure sulfur. By using SSCReF to construct packed-bed reactors, the highest denitrification and dephosphorization rates reached 829.70 gN/m 3 /d (25 wt % siderite) and 36.70 gP/m 3 /d (75 wt % siderite), respectively. Dephosphorization was demonstrated to be dependent on sulfur-driven denitrification, in which the acid produced from the later process promoted Fe (II) dissolution, which then directly combined with phosphate to form vivianite or further converted into phosphate adsorbents (ferrihydrite, a green rust-like compound). Water flush was an effective way to finally wash out these surface deposited Fe−P compounds, as well as those nonreactive impurities (Si and Al-bearing compounds) detached from SSCReF. Such a highly efficient and safe SSCReF holds considerable application potential in secondary effluent polishing.

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Assessing the Solubilities and Reaction Kinetics of Aluminous Minerals in Soils

May

Nordstrom

1991

Soil Acidity

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Well-Ordered Kaolinite in Siderite Concretions from the Brazil Formation, Western Indiana

Cited by 8 publications

References 3 publications

Mineralogy of the rhizosphere in forest soils of the eastern United States

Mineralogy of the rhizosphere in forest soils of the eastern United States

Highly Efficient Coremoval of Nitrate and Phosphate Driven by a Sulfur-Siderite Composite Reactive Filler toward Secondary Effluent Polishing

Assessing the Solubilities and Reaction Kinetics of Aluminous Minerals in Soils

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