The iron-tungsten-sulphur system and its geological application

Steam injection is attracting a considerable interest in terms of EOR. In this work the oil-saturated sandstones and their extracts (Ashalcha field) were subjected to hydrothermal heating in the presence of iron oxide (II, III) nanoparticles in an autoclave at a 200 °C and 250 °C for 24 hours. SARA analysis revealed that the destruction of resins and asphaltenes is observed after thermo-catalytic treatment at 250 °C; at 200 °C iron oxide is ineffective. This destruction led to increase the amount of oil saturates fraction, as GC-MS data and the formation of coke-like substances adsorbed on sandstone (TG-DSC data).

Magnetic parameters as proxies for anthropogenic pollution in water reservoir sediments from Mexico: An interdisciplinary approach

Historically as part of its national security mission, the U.S. Department of Energy’s Y-12 National Security Facility in Oak Ridge, TN, USA acquired a significant fraction of the world’s supply of elemental mercury. During the 1950’s and 1960’s, a large amount of elemental mercury escaped confinement and is still present in the buildings and grounds of the Y-12 Facility and in the Y-12 Watershed. Because of the adverse effects of elemental mercury and mercury compounds upon human health, the Oak Ridge Site is engaged in an ongoing effort to monitor and remediate the area. The main thrust of the Oak Ridge mercury remediation effort is currently scheduled for implementation in FY09. In order to more cost effectively implement those extensive remediation efforts, it is necessary now to obtain an improved understanding of the role that mercury and mercury compounds play in the Oak Ridge ecosystem. Most recently, concentrations of both total mercury and methylmercury in fish and water of lower East Fork Poplar Creek (LEFPC) of Oak Ridge increased although the majority of mercury in the site is mercury sulfide. This drives the US DOE and the Oak Ridge Site to study the long-term bioavailability of mercury and speciation at the site. The stability and bioavailability of mercury sulfide as affected by various biogeochemical conditions –presence of iron oxides have been studied. We examined the kinetic rate of dissolution of cinnabar from Oak Ridge soils and possible mechanisms and pathways in triggering the most recent increase of mercury solubility, bioavailability and mobility in Oak Ridge site. The effects of pH and chlorine on oxidative dissolution of cinnabar from cinnabar-contaminated Oak Ridge soils is discussed. On the other hand, aquatic plants might be good candidate for phytoremediate contaminated waste water and phytofiltration of collective storm water and surface runoff and river. Our greenhouse studies on uptake of Hg by water lettuce (Pistia stratiotes) show that water lettuce is effectively removing Hg from water solution and Hg was mostly stored in roots. One day of growing could remove 93–98% of Hg from water solutions. However, Hg shows acute toxicity to water lettuce as indicated by decreases in fresh biomass and moisture contents.

The construction industry is demanding more and more quality decorative cements. The demand for them and the requirements for their performance are constantly growing. But since decorative cements are based on white Portland cement, their production is associated with the disadvantages of the production of all clinker cements  low environmental friendliness, high energy consumption and high prices. They are not always able to provide decorative ecological and comfortable coatings with increased performance. In addition, many countries do not produce it and have to import it. An effective alternative to decorative clinker cements can be decorative slag-alkaline cement obtained from industrial waste. It also provides a number of special properties  a wide range of colors, color fastness, high strength, high adhesion, durability and many others. But the problem associated with the use of slag-alkaline cements as decorative cements with high linen ( 70%) is the unstable chemical composition of the slag and, first of all, the different presence of iron oxides in it. It is shown that the presence of iron oxides can reduce the whiteness of decorative slag-alkaline cements due to the synthesis of compounds in them, which give the samples of blue-green color and due to the presence of iron oxides proper, which are inherent in color from brown to dark brown. The paper shows the regularities of the influence of the chemical composition of blast-furnace slags on the whiteness of an artificial slag-alkaline stone. Possibilities of obtaining decorative alkali-activated cements with a wide range of whiteness  from 70 to 97% are shown. Methods of reducing the cost of slag-alkaline decorative cements by using a complex bleaching additive, where part of the expensive TiO2 can be replaced by kaolin or CaCO3, are shown. A new method for determining the whiteness of hardened materials is proposed.

The depletion of iron and sulphur into dust in the interstellar medium and the exact nature of interstellar amorphous silicate grains is still an open question. We study the incorporation of iron and sulphur into amorphous silicates of olivine- and pyroxene-type and their effects on the dust spectroscopy and thermal emission. We used the Maxwell-Garnett effective-medium theory to construct the optical constants for a mixture of silicates, metallic iron, and iron sulphide. We also studied the effects of iron and iron sulphide in aggregate grains. Iron sulphide inclusions within amorphous silicates that contain iron metal inclusions shows no strong differences in the optical properties of the grains. A mix of amorphous olivine- and pyroxene-type silicate broadens the silicate features. An amorphous carbon mantle with a thickness of 10 nm on the silicate grains leads to an increase in absorption on the short-wavelength side of the 10 $\mu$m silicate band. The assumption of amorphous olivine-type and pyroxene-type silicates and a 10 nm thick amorphous carbon mantle better matches the interstellar silicate band profiles. Including iron nano-particles leads to an increase in the mid-IR extinction, while up to 5 ppm of sulphur can be incorporated as Fe/FeS nano inclusions into silicate grains without leaving a significant trace of its presence.

Abstract. Cryoconite is a mixture of impurities and ice visually represented by dark colors present in the ablation zone of glaciers. As an important constituent of light-absorbing impurities on the glacier surface, iron oxides influence the radiative properties of mineral dust and thus its impact on ice melting processes. In particular, the distinct optical properties between hematite and goethite (the major iron oxide species) highlight the necessity to obtain accurate knowledge about their abundance and geochemical behavior. Cryoconite samples from five glaciers in different regions of the Tibetan Plateau (TP) and surroundings were studied. The iron abundance in the cryoconite from TP glaciers ranged from 3.40 % to 4.90 % by mass, in accordance with typical natural background levels. Because the light absorption capacity of mineral dust essentially depends on the presence of iron oxides (i.e., free iron), iron oxides were extracted and determined using diffuse reflectance spectroscopy. The ratios of free to total iron for the five glaciers ranged from 0.31 to 0.70, emphasizing that iron in the form of oxides should be considered rather than total iron in the albedo and radiative modeling. Furthermore, the goethite content in iron oxides (in mass fraction) ranged from 81 % to 98 %, showing that goethite was the predominant form among the glaciers. Using the abundance and speciation of iron oxides as well as their optical properties, the total light absorption was quantitatively attributed to goethite, hematite, black carbon (BC) and organic matters at 450 and 600 nm wavelengths. We found that the goethite played a stronger role than BC at shorter wavelengths for most glaciers. Such findings were essential to understand the relative significance of anthropogenic and natural effects, and then taking the proper mitigation measures.

Nowadays, it is especially important and relevant to improve the efficiency of existing methods of enhanced oil recovery, in particular, thermal methods using water steam. The use of catalysis at the stage of development of unconventional hydrocarbon fields, namely super-viscous and bituminous oils, will allow solving this problem. This work is devoted to the study of the transformation of heavy oil from the Ashalchinskoye field in the process of catalytic aquathermolysis. The oil samples were extracts from sandstone, which was subjected to thermal steam treatment in a high-pressure reactor at temperatures of 200 and 250C for 24 h. Nanosized iron (II, III) oxide in complex with a hydrogen donor was used as a catalytic composition. According to the results of SARA-analysis, it was found that at a temperature of 200C, iron oxide does not show its catalytic properties, and there is no noticeable improvement in the composition of heavy oil. The destruction of resins and asphaltenes is observed after thermocatalytic treatment at 250C. This leads to the enrichment of oil with lighter hydrocarbons, which is confirmed by GC-MS data of the saturated fraction of oil. All this provides a significant decrease in the viscosity of heavy oil compared to the non-catalytic process from 1140 cP to 37 cP The formation of coke-like substances adsorbed on sandstone as a result of thermocatalytic action at 250C was revealed by the results of TG-DSC.

Lead immobilization by phosphate in the presence of iron oxides: Adsorption versus precipitation

Investigation of irradiated soil byproducts

Black particles, collected by filtration (1.2‐µm pore size) from the anoxic waters of a soft‐water lake, were examined by a scanning proton microprobe which permitted quantitative elemental analysis by proton‐induced X‐ray emission (PIXE) and Rutherford backscattering (RBS). There was a uniform distribution of sulfur across the filter, but Fe, and to a lesser extent, Mn, was localized in ∼5‐µm‐diameter clusters. Elemental analysis with 1‐µm‐diameter beams revealed that the Fe clusters were mainly comprised of iron oxides. Iron sulfide material not in the Fe clusters had stoichiometric proportions of Fe1.0S0.60P0.60Ca0.24K0.14. Although a purely biogenic origin for P, Ca, and K cannot be ruled out, the composition is consistent with the particles originating as authigenic iron oxides which react with sulfide as they sink through the water column. The iron sulfide particles are richer in Cu (4,000 ppm) and Zn (6,000 ppm) than the iron oxides, suggesting that these elements are also concentrated as their insoluble sulfides. The coexistence of iron oxides and sulfides indicates that either the supply of sulfide is limiting or that some iron oxide particles are unreactive.

Resilience of soils with different texture, mineralogy and organic matter under long-term conservation systems

When exposed to an alternating magnetic field, superparamagnetic nanoparticles can elicit the required hyperthermic effect while also being excellent magnetic resonance imaging (MRI) contrast agents. Their main drawback is that they diffuse out of the area of interest in one or two days, thus preventing a continuous application during the typical several-cycle multi-week treatment. To solve this issue, our aim was to synthesise an implantable, biodegradable membrane infused with magnetite that enabled long-term treatment while having adequate MRI contrast and hyperthermic capabilities. To immobilise the nanoparticles inside the scaffold, they were synthesised inside hydrogel fibres. First, polysuccinimide (PSI) fibres were produced by electrospinning and crosslinked, and then, magnetitc iron oxide nanoparticles (MIONs) were synthesised inside and in-between the fibres of the hydrogel membranes with the well-known co-precipitation method. The attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) investigation proved the success of the chemical synthesis and the presence of iron oxide, and the superconducting quantum interference device (SQUID) study revealed their superparamagnetic property. The magnetic hyperthermia efficiency of the samples was significant. The given alternating current (AC) magnetic field could induce a temperature rise of 5 °C (from 37 °C to 42 °C) in less than 2 min even for five quick heat-cool cycles or for five consecutive days without considerable heat generation loss in the samples. Short-term (1 day and 7 day) biocompatibility, biodegradability and MRI contrast capability were investigated in vivo on Wistar rats. The results showed excellent MRI contrast and minimal acute inflammation.

The reduction of dense Wustite plate was investigated over the temperature range of 600 to 1200°C, using hydrogen containing hydrogen sulphide and water vapour of various contents in such proportions that metallic iron remains stable. Sulphur in the reducing gas affects remarkably the kinetics of the reduction of Wustite and the morphology of reduced iron. The following results were obtained.(1) In the reduction at 800 and 1000°C, sulphur in the reducing gas of content just below that for the formation of iron sulphide extensively enhances the reduction of Wustite due to the formation of porous iron rather than dense iron, and, conversely, sulphur of extremely low content compared with that in equilibrium with iron sulphide retards the reduction due to the formation of dense iron.(2) The addition of both water vapour and hydrogen sulphide to hydrogen stops the reduction at 600°C, in spite of their low concentrations.(3) In the reduction at 1000 and 1200°C, the reduction rate becomes smaller by the addition of sulphur, in which case the coarsening of metallic iron is observed.

The reduction of dense Wustite plate was investigated over the temperature range of 600 to 1200°C, using hydrogen containing hydrogen sulphide and water vapour of various contents in such proportions that metallic iron remains stable. Sulphur in the reducing gas affects remarkably the kinetics of the reduction of Wustite and the morphology of reduced iron. The following results were obtained.(1) In the reduction at 800 and 1000°C, sulphur in the reducing gas of content just below that for the formation of iron sulphide extensively enhances the reduction of Wustite due to the formation of porous iron rather than dense iron, and, conversely, sulphur of extremely low content compared with that in equilibrium with iron sulphide retards the reduction due to the formation of dense iron.(2) The addition of both water vapour and hydrogen sulphide to hydrogen stops the reduction at 600°C, in spite of their low concentrations.(3) In the reduction at 1000 and 1200°C, the reduction rate becomes smaller by the addition of sulphur, in which case the coarsening of metallic iron is observed.

Anaerobic dechlorination of chlorophenols often subjects to their toxicity and recalcitrance, presenting low loading rate and poor degradation efficiency. In this study, in order to accelerate p-chlorophenol (p-CP) reduction and extracellular electron transfer in an anaerobic system, three iron-oxide nanoparticles, namely hematite, magnetite and ferrihydrite, were coupled into an anaerobic system, with the performance and underlying role of iron-oxide nanoparticles elucidated. The reductive dechlorination of p-CP was notably improved in the anaerobic systems coupled by hematite and magnetite, although ferrihydrite did not plays a positive role. Enhanced dechlorination of p-CP in hematite or magnetite coupled anaerobic system was linked to the obvious accumulation of acetate, lower oxidation–reduction potential and pH, which were beneficial for reductive dechlorination. Electron transfer could be enhanced by Fe2+/Fe3+ redox couple on the iron oxides surface formed through dissimilatory iron-reduction. This study demonstrated that the coupling of iron-oxide nanoparticles such as hematite and magnetite could be a promising alternative to the conventional anaerobic reduction process for the removal of CPs from wastewater.