scholarly journals Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer Using Methods for the Extraction of Uranium with Different Strength Reagents in Combination with Groundwater Data

2019 ◽  
Author(s):  
Alexander I. Malov ◽  
Sergey B. Zykov
Keyword(s):  
Iron Oxides ◽  
Extraction Procedure ◽  
Retardation Factor ◽  
Uranium Isotopes ◽  
Iron Hydroxides ◽  
Carbonate Minerals ◽  
Amorphous Iron ◽  
Mineral Phases ◽  
Clay Deposits ◽  
Total Digestion

A partial extraction procedure was used to study the distribution of uranium in the mineral phases of rocks of an aquifer of sandy-clay deposits of the Vendian in the northwest of Russia. This work is a part of a research project to develop a method for combined radiocarbon and uranium-isotope dating of groundwater. Representative aliquots of each core sample were subjected to five "partial" extractions by treatment with: distilled water, low mineralized fresh natural groundwater, minopolycarboxylic acid chelating agent (0.05M EDTA), 0.5M HCl, 15M HNO3, and a total digestion, with U isotopes reported in this study for each procedure. The following mineral phases of core samples: adsorbed material, carbonate minerals, amorphous iron oxides, aluminosilicates partial digestion and a crystalline iron oxides, aluminosilicates total digestion and a clay/quartz resistate were characterized. Red-colored siltstones depleted in uranium in relatively readily soluble mineral phases. The concentration of adsorbed uranium was established in the amount of 15.8±2.1 - 30.5±3.9 μg/kg. Carbonate minerals contain even less of this element. In iron hydroxides and the most readily soluble aluminosilicates, its concentrations are in the range 168±24 - 212±28 μg/kg. The most insoluble fraction contains 1.65±0.21 - 4.32±0.45 mg/kg of uranium. In green-colored siltstones, the concentration of adsorbed uranium is much higher: 106±14 - 364±43 μg/kg. Carbonate minerals and amorphous iron oxides contain 1.91±0.21 - 2.34±0.26 mg/kg of uranium. In aluminosilicates and a clay/quartz resistate, uranium concentrations are 5.6±0.5 - 16.8±1.4 mg/kg. Elevated values of 234U:238U activity ratio prevail in the adsorbed material and iron hydroxides. In aluminosilicates and clay/quartz resistate, the values decrease. This indicates the replacement of primary sedimentogenic uranium by secondary hydrogenic uranium adsorbed on the surface of minerals and coprecipitated with iron hydroxides. The results obtained made it possible to carry out preliminary quantitative estimates of the retardation factor and recoil loss factor of uranium in the groundwater of siltstones of the studied Vendian aquifer.

scholarly journals Study of the Mobilization of Uranium Isotopes in a Sandstone Aquifer in Combination with Groundwater Data

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 112
Author(s):  
Alexander I. Malov ◽  
Sergey B. Zykov
Keyword(s):  
Iron Oxides ◽  
Extraction Procedure ◽  
Chelating Agent ◽  
Retardation Factor ◽  
Uranium Isotopes ◽  
Iron Hydroxides ◽  
Carbonate Minerals ◽  
Amorphous Iron ◽  
Mineral Phases ◽  
Clay Deposits

This work is part of a research project that aims to develop a method for combined radiocarbon and uranium-isotope dating of groundwater. The specific objective of this study was to investigate the mobility of uranium isotopes in the various mineral phases of rocks of an aquifer of sandy-clay deposits of the Vendian in the northwest of Russia, for which a partial extraction procedure was used. Representative aliquots of each core sample were treated with various reagents: distilled water, low mineralized fresh natural groundwater, minopolycarboxylic acid chelating agent (0.05 M EDTA), 0.5M HCl, 15 M HNO3, as well as total digestion, and the U isotope data for each procedure are reported in this study. The following mineral phases of core samples were characterized: sorbed material, carbonate minerals, amorphous iron oxides, partially soluble aluminosilicates and crystalline iron oxides, totally digestible aluminosilicates and a clay/quartz resistate. Red-colored siltstones and sandstones were depleted in uranium in relatively readily soluble mineral phases. The concentration of sorbed uranium was established in the range 15.8 ± 2.1–30.5 ± 3.9 μg/kg and carbonate minerals contained even less uranium. For iron hydroxides and the most readily soluble aluminosilicates, uranium concentrations were in the range 168 ± 24–212 ± 28 μg/kg. The most insoluble fraction contained uranium in the range 1.65 ± 0.21–4.32 ± 0.45 mg/kg. In green-colored siltstones, the concentration of sorbed uranium was much higher in the range 106 ± 14–364 ± 43 μg/kg. Carbonate minerals and amorphous iron oxides contained uranium in the range 1.91 ± 0.21–2.34 ± 0.26 mg/kg. In aluminosilicates and a clay/quartz resistate, uranium concentrations were in the range 5.6 ± 0.5–16.8 ± 1.4 mg/kg. Elevated values of 234U:238U activity ratio prevailed in the sorbed material and iron hydroxides. In aluminosilicates and clay/quartz resistate, the values decreased. This indicates the replacement of primary sedimentogenic uranium by secondary hydrogenic uranium sorbed on the surface of minerals and coprecipitation with iron hydroxides. The results obtained made it possible to carry out preliminary quantitative estimates of the retardation factor and recoil loss factor of uranium in the groundwater of siltstones and sandstones of the studied Vendian aquifer.

scholarly journals Distribution of Uranium Isotopes in Sandy Deposits by Sequential Extraction

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 467
Author(s):  
Alexander I. Malov ◽  
Sergey B. Zykov ◽  
Alexey S. Tyshov
Keyword(s):  
Sequential Extraction ◽  
Extraction Procedure ◽  
Sedimentary Basins ◽  
Retardation Factor ◽  
Uranium Isotopes ◽  
Complex Nature ◽  
Carbonate Minerals ◽  
Fresh Groundwater ◽  
Mineral Phases ◽  
Amorphous Minerals

The sequential extraction procedure is used to reconstruct the processes of redistribution of uranium isotopes in the mineral phases of the aquifer of the Vendian sandy-argillaceous deposits developed in the coastal territory of the European North of Russia. This aquifer has large resources of drinking and mineral groundwater which, however, are used in extremely limited quantities. This is due to the very complex nature of the hydrochemical conditions, and uranium-isotopic methods are used to clarify these conditions. The following mineral phases of core samples were characterized: adsorbed trace materials and carbonate minerals; ferrihydrate, amorphous minerals of Fe, Al and Si, and secondary U minerals; crystalline iron minerals; clay and some refractory minerals; and all remaining resistant minerals. The most resistant minerals, whose fraction ranges from 70.58 to 96.4%, have a minimum average uranium concentration of 0.47 ppm. This uranium is practically conserved in the rock, as a result of which the average ratio of its 234U:238U isotopes is close to equilibrium. In the remaining fractions, uranium is redistributed by groundwater along their flow lines from recharge areas in watersheds to areas of discharge into river valleys. Its maximum concentration (12.89 ppm) measurement is carried out by coprecipitation with iron hydroxides, then the uranium is adsorbed and precipitated with carbonates (9.14 ppm). The average 234U:238U is maximum in adsorbed trace materials and carbonate minerals (2.39 ± 0.36) and is close to that in fresh groundwater (2.8 ± 0.42). It is also increased in the amorphous minerals of Fe (1.53 ± 0.23). In general, there is a dependence of the 234U:238U activity ratio in rock on the degree of participation of groundwater in the deposition of hydrogenic uranium isotopes into the cracks and pores of these rocks. The results obtained contribute to the refinement of such a parameter as the retardation factor, which is necessary for understanding the processes of migration and concentration of uranium in sedimentary basins.

Liquid-phase aldol condensation of cyclohexanone on aluminium and iron oxides

1982 ◽  
Vol 47 (8) ◽  
pp. 2235-2245 ◽  
Author(s):  
Zdeněk Vít ◽  
Lubomír Nondek ◽  
Jaroslav Málek
Keyword(s):  
Iron Oxides ◽  
Aldol Condensation ◽  
Condensation Reaction ◽  
Complex Function ◽  
Acid Sites ◽  
Basic Site ◽  
Catalyst Poisoning ◽  
Iron Hydroxides ◽  
Transient Complex ◽  
Kinetics Of

The kinetics of the aldol condensation of cyclohexanone in decalin were investigated at 210 °C on catalysts prepared by drying and calcining the aluminium and iron hydroxides at 110-850 °C. The effect of catalyst poisoning by benzoic acid and pyridine on the course of the condensation reaction and aldol retroaldolisation was also examined. The kinetics of the cyclohexanone condensation can be described by means of Langmuir-Hinshelwood equations which are in agreement with a mechanism involving adsorption of cyclohexanone on a basic site to form a transient complex, reaction of this complex with a cyclohexanone molecule affording the aldol, the rate determining interaction of the aldol with free basic and acid sites yielding 2-(1-cyclohexen-1-yl)cyclohexanone and water and desorption of these products from the catalyst surface. The proposed kinetic model is supported by the results of catalyst poisoning. The activity of aluminium and iron oxides in the condensation of cyclohexanone is a complex function of their basicity and acidity depending strongly on the calcination temperature.

Genesis of kaolin deposits of Birbhum, West Bengal, India

Clay Minerals ◽  
1969 ◽  
Vol 8 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Bibhuti Mukherjee ◽  
M. G. Rao ◽  
C. Karunakaran
Keyword(s):  
Trace Elements ◽  
West Bengal ◽  
Intimate Relationship ◽  
Element Distribution ◽  
Trace Element Distribution ◽  
Minor And Trace Elements ◽  
Clay Deposit ◽  
Mineral Phases ◽  
Clay Deposits ◽  
Relationship Of

The mineral phases and the distribution of major, minor and trace elements in the clays and bed rocks of two bore-holes at Adda and Chaubatta of the Birbhum area have revealed an intimate relationship of the kaolin-rich clays with the bed-rock of Adda. The possibility of a common origin for the clay deposits at Chaubatta, lying close to the Rajmahal trap formations, and at Adda, lying close to the Archaean boundary, has been inferred from trace element distribution and other factors. A genetic relationship of the clay deposit at Adda with the bed-rock, altered Archaean gneiss, has been established, but there is no significant relationship of the Chaubatta clay deposit with its bed-rock, the weathered basalt.The lateritic cappings above the kaolin-rich clays of Adda and Chaubatta areas are explained as being formed from kaolinite in the weathering sequence as the end-product of intensive desilication under conditions of intensive leaching and increasing acidity near the surface.

Identification of Mixed-Layer Mineral of Cambodian Clays and their Phase Changes upon Firing

2012 ◽  
Vol 620 ◽  
pp. 72-76
Author(s):  
Bun Kim Ngun ◽  
Mohamad Hasmaliza ◽  
Kiyoshi Okada ◽  
Phat Bone ◽  
Zainal Arifin Ahmad
Keyword(s):  
Mixed Layer ◽  
Mineralogical Composition ◽  
Xrd Analysis ◽  
Phase Changes ◽  
Rational Analysis ◽  
Qualitative And Quantitative ◽  
Mineral Phases ◽  
Clay Deposits ◽  
Layer Mineral

Representative of clay deposits from central Cambodia were analyzed in terms of their mineral phases, mineralogical composition and phase changes after firing by qualitative and quantitative XRD analysis. To examine the phase changes, the samples were prepared and fired from 950 to 1200 °C. Results show that Cambodian clays contained quartz, illite, kaolinite, and chlorite-vermiculite mixed-layer as dominant mineral phases and the minor phases of albite and calcite also appeared in the samples. The rational analysis shows that chlorite-vermiculite was the main mineral in all Cambodian clays. After the samples were preceded upon firing, new phases of mullite, hematite and crystobalite were appeared above 1050 °C.

scholarly journals Environmental Impacts and Immobilization Mechanisms of Cadmium, Lead and Zinc in Geotechnical Composites Made from Contaminated Soil and Paper-Ash

2021 ◽  
Vol 11 (24) ◽  
pp. 11822
Author(s):  
Marija Đurić ◽  
Primož Oprčkal ◽  
Vesna Zalar Serjun ◽  
Alenka Mauko Pranjić ◽  
Janez Ščančar ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Contaminated Soils ◽  
Methodological Approach ◽  
Extraction Procedure ◽  
Water Soluble ◽  
Mineral Phases ◽  
Lead And Zinc ◽  
Remediation Efficiency ◽  
Cadmium Lead ◽  
One Year

Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.

scholarly journals Coffee plantation soil characterization using a multi-method approach near the Volcano Nevado del Ruiz, Colombian Central Cordillera

2021 ◽  
Vol 25 (3) ◽  
pp. 263-273
Author(s):  
Brahiam Hincapié ◽  
Alexander Cortés-Soto ◽  
Mauricio A Bermudez ◽  
Santiago Yepez ◽  
Juan Sebastián Trujillo-Hernández ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Iron Oxides ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mößbauer Spectroscopy ◽  
Mineral Phases ◽  
Multi Method Approach ◽  
Sentinel 2A ◽  
Spectral Imager

The presence of iron oxides may provide a sensitive indicator of the effects of cropping practices on coffee plantations. Authors characterized the mineral phases present in soil A horizons at three different farms located in the Department of Tolima within the regions of Líbano and Villahermosa. Our analysis includes X-ray diffraction, Mössbauer spectroscopy, and remote sensing to discriminate the distribution of the different magnetic mineral phases. X-ray diffraction was used to identify the mineralogical properties of iron oxide such as hematite, goethite, and ferrihydrite (Fh), as well as tectosilicate minerals such as albite and sanidine. Mössbauer spectroscopy results for samples taken at room temperature indicate the presence of Fe2+ and Fe3+ mineral phases, which possibly correspond to ilmenite or magnetite. Finally, Sentinel-2A multi-spectral imager (MSI) data was used to map the distribution of iron oxides and study the influence of their distribution throughout the study area. A high correlation between Mössbauer spectroscopy and Sentinel-2A MSI data exists throughout the study area. The results suggest that farms close to the main Nevado del Ruíz Volcano have a more significant mineralogical variability. In contrast, more distant farms are characterized by soils with more iron oxides, the product of weathering, erosion, and human activities.

Balneaves: Soil Thin Sections

1992 ◽  
Vol 58 (S2) ◽  
pp. 23-25
Author(s):  
Donald Davidson
Keyword(s):  
Iron Oxides ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
Random Pattern ◽  
Medium Sand ◽  
Thin Sections ◽  
Amorphous Iron ◽  
Channel Pattern ◽  
Mineral Components ◽  
Quartz Grains

1. Structure: partially accommodated channels (0.16 to 0.80mm in width) above the pan; no aggregates; fewer channels below the pan; channel pattern - straight to curved; vughs (spherical to elongate, not normally connected) 0.4 to 0.8mm in diameter and are not orientated and have random pattern: above pan channels and vughs partially connected; pellicular grain microstructure - weakly developed.2. Mineral components: coarse fraction: quartz grains range in size from silt to fine/medium sand (<lmm). One large quartz (200mm). Dominance of single and compound quartz grains; instances of biotite and plagioclase; quartz grains -angular/subangular and smooth. Fine fraction: brown, optically amorphous iron oxides, isotropic.

Tritium exchange studies on metal oxide colloidal dispersions

1977 ◽  
Vol 30 (8) ◽  
pp. 1655 ◽  
Author(s):  
DE Yates ◽  
F Grieser ◽  
R Cooper ◽  
TW Healy
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Iron Oxide ◽  
Metal Oxide ◽  
Iron Oxides ◽  
Colloidal Dispersions ◽  
Water Interface ◽  
Amorphous Iron ◽  
Tio2 Rutile ◽  
Exchange Technique

The tritium exchange technique has been used to detemine the maximum number of surface protons at the oxide-water interface for oxide colloids including silicas, TiO2 (rutile) and the iron oxides goethite, hematite and amorphous iron oxide. The effects of heat treatment, crystal structure and exchange conditions are considered and tritium exchange values for the number of surface protons are compared with values calculated from crystal structures.

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