illite and goethite

Soils formed after the desiccation of Lake Atamanskoe, which has served as a reservoir for liquid industrial waste from the city of Kamensk-Shakhtinsky during a long time, were studied. These soils differ from zonal soils by a strong contamination with zinc and sulfur. Preliminary studies showed that Fe compounds fix a significant part of zinc. This requires to study S, Zn, and Fe minerals. In this work, Mössbauer spectroscopy was used for the identification of iron compounds and scanning electron microscopy was used for the microanalysis of these and other minerals. To facilitate the identification of Fe minerals, brown iron ocher was removed from a contaminated soil sample and analyzed. From electron microscopy and Mössbauer spectroscopy data, ocher contained hydrogoethite with a high content of sorption water and schwertmannite (a rare mineral, probably found in Russia for the first time). The chemical composition of this schwertmannite better corresponds to the Cashion-Murad model than to the Bigham model. Particles of partially oxidized magnetite and wustite enriched with zinc were revealed under electron microscope. Siderite with partial substitution of Fe

Topics: Carbonates; Ferric Compounds; Ferrous Compounds; Iron; Iron Compounds; Minerals; Russia; Soil; Soil Pollutants; Sulfur; Zinc

Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily impacted by wastewater discharge shows similar coating textures and chemical compositions. Major constituents of the coating include Al-substituted goethite and illite/chlorite clays. Goethite is aggregated into well-crystallized domains through oriented attachment resulting in increased porosity. Illite/chlorite clays with various chemical compositions were observed to be mixed with goethite aggregates and aligned sub-parallel to the associated quartz surface. The uniform spatial distribution of wastewater-derived phosphorus throughout the coating from the wastewater-contaminated site suggests that all of the coating constituents, including those adjacent to the quartz surface, are accessible to groundwater solutes. Both TEM characterization and chemical extraction results indicate there is a significantly greater amount of amorphous iron oxide in samples from wastewater discharge area compared to those from the pristine region, which might reflect the impact of redox cycling of iron under the wastewater-discharge area. Coating compositions are consistent with the moderate metal and oxy-metalloid adsorption capacities, low but significant cation exchange capacities, and control of iron(III) solubility by goethite observed in reactive transport experimental and modeling studies conducted at the site.

Topics: Adsorption; Aluminum; Chlorides; Electron Probe Microanalysis; Ferric Compounds; Geologic Sediments; Iron Compounds; Massachusetts; Microscopy, Electron, Transmission; Minerals; Phosphorus; Quartz; Silicon; Silicon Dioxide; Water Pollutants, Chemical

To ensure safe and efficient geologic CO(2) sequestration (GCS), it is crucial to have a better understanding of CO(2)-brine-rock interactions under GCS conditions. In this work, using biotite (K(Mg,Fe)(3)AlSi(3)O(10)(OH,F)(2)) as a model clay mineral, brine-biotite interactions were studied under conditions relevant to GCS sites (95 °C, 102 atm CO(2), and 1 M NaCl solution). After reaction for 3-17 h, fast growth of fibrous illite on flat basal planes of biotite was observed. After 22-70 h reaction, the biotite basal surface cracked, resulting in illite detaching from the surface. Later on (96-120 h), the cracked surface layer was released into solution, thus the inner layer was exposed as a renewed flat basal surface. The cracking and detachment of the biotite surface layer increased the surface area in contact with solution and accelerated biotite dissolution. On biotite edge surfaces, Al-substituted goethite and kaolinite precipitated. In control experiments with water under the same temperature and pressure, neither macroscopic fibrous illite nor cracks were observed. This work provides unique information on biotite-brine interaction under acidic hydrothermal conditions.

Topics: Aluminum Silicates; Carbon Sequestration; Ferrous Compounds; Hydrogen-Ion Concentration; Iron Compounds; Kaolin; Minerals; Pressure; Seawater; Spectrometry, X-Ray Emission; Surface Properties; Temperature

Sorption of the endocrine-disrupting chemical 17beta-estradiol (E(2)) from aqueous solutions to goethite, an iron oxide, and the clay minerals kaolinite, illite, and montmorillonite (K and Ca forms) was measured at 25 degrees C. The clay minerals sorbed more E(2) than the oxide, with sorption capacity increasing in the order goethite

Topics: Adsorption; Bentonite; Estradiol; Iron Compounds; Kaolin; Minerals; Soil